WO2024080902A1

WO2024080902A1 - System and method for monitoring and/or controlling an internal state of a centrifugal pump

Info

Publication number: WO2024080902A1
Application number: PCT/SE2023/000010
Authority: WO
Inventors: Tim SUNDSTRÖM
Original assignee: S.P.M Instrument Ab
Priority date: 2022-10-10
Filing date: 2023-10-10
Publication date: 2024-04-18

Abstract

A method for monitoring and/or operating a pump (10; 10A; 10B; 10C; 10D) having a casing in which a rotatable part (20, 2000) is disposed for urging a fluid material (30) from an inlet to an outlet, the method comprising: receiving a measuring signal indicative of a vibration in the casing and/or a fluid pressure pulsation (P_FP) in the fluid material (30); receiving a reference signal indicative of a rotational reference position of said rotating part (20, 2000); generating data indicative of an internal state of the pump, said data including a phase value (FI, FI(r), X1(r)) and/or a temporal relation value (FI, FI(r), X1(r)) based on said measuring signal and said reference signal.

Description

SYSTEM AND METHOD FOR MONITORING AND/OR CONTROLLING AN INTERNAL STATE OF A CENTRIFUGAL PUMP

Technical Field

The present invention relates to the field of a pump and to the monitoring of a pump. The present invention also relates to the field of control of a pump. The present invention also relates to a method and to an apparatus for monitoring of an internal state of a pump. The present invention also relates to a method and to an apparatus for controlling an internal state of a pump. The present invention also relates to a computer program for monitoring of an internal state of a pump. The present invention also relates to a computer program for controlling an internal state of a pump.

Description of Related Art

In some industries, such as in the paper production industry, there is a need to transport fluid material, such as pulp. Also in the mining industry, there is a need to transport fluid material. Other industries, such as the dairy industry, also have a need to transport fluids, such as milk products. Moreover, there is a need to transport fluid material, such as water, in many instances of modem society, such as for providing water to a water tower and/or providing water for irrigation purposes in the farming industry.

A centrifugal pump can achieve transportation of fluid material. For this purpose a centrifugal pump has a rotatable part fitted with vanes and known as an impeller. The impeller imparts motion to the fluid which is directed through the pump. The pressure for achieving the required head is produced by centrifugal acceleration of the fluid in the rotating impeller. The fluid may flow axially towards the impeller, is deflected by it and flows out through apertures between the vanes. Thus, the fluid undergoes a change in direction and is accelerated. This produces an increase in the pressure at the pump outlet. The fluid exits the impeller into a volute, which collects the flow and directs it towards the pump outlet. The volute is a gradual widening of the spiral casing of the pump. Alternatively, when leaving the impeller, the fluid may first pass through a ring of fixed vanes which surround the impeller and is commonly referred to as a diffuser, before entering the volute and being passed to the pump outlet. The operation of a centrifugal pump is often discussed in terms involving the concept of an operating point of the pump. US 2003/0129062 (ITT Fluid Technology) discloses that the operating point of a pump is commonly thought of as the flow rate and Total Dynamic Head (TDH) that the pump is delivering. US 2003/0129062 also discloses a method for determining the operating point of a centrifugal pump based on motor torque and motor speed. According to US 2003/0129062 a method for determining whether a centrifugal pump is operating in a normal flow operating range includes the steps of: determining a motor torque/TDH relationship over a range of speeds for a minimum flow rate in order to obtain a minimum flow operating range for the centrifugal pump; determining a motor torque/TDH relationship over a range of speeds for a maximum flow rate in order to obtain a maximum flow operating range for the centrifugal pump; determining the actual operating motor torque and TDH of the centrifugal pump at a given operating point; and determining whether the actual operating motor torque and TDH of the centrifugal pump falls within the minimum flow and maximum flow operating ranges of the centrifugal pump.

US 9,416,787 B2 (ABB Technology Oy) discloses that the flow rate to head curve (QH curve) and the flow rate to power curve (QP curve) of the pump are provided by the pump manufacturer, and can be available for all pumps. US 9,416,787 B2 also discloses a method for determining the flow rate (Q) produced by a pump, when the pump is controlled with a frequency converter, which produces estimates for rotational speed and torque of the pump, and the characteristic curves of the pump are known. The method includes determining the shape of a QH curve of the pump, dividing the QH curve into two or more regions depending on the shape of the QH curve, determining on which region of the QH curve the pump is operating, and determining the flow rate (Q) of the pump using the determined operating region of the characteristic curve.

Summary

In view of an aspect of the state of the art, a problem to be addressed is how to provide an improved manner of identifying an internal state of a pump during operation. This problem is addressed by examples, such as by a method and/or a system and/or a pump, as disclosed in this disclosure. In view of an aspect of the state of the art, a problem to be addressed is how to provide an improved manner of optimizing the operation of a pump. This problem is addressed by examples, such as by a method and/or a system and/or a pump, as disclosed in this disclosure. In view of an aspect of the state of the art, a problem to be addressed is how to improve the efficiency of the pumping process in a centrifugal pump. This problem is addressed by examples, such as a system and or a pump and/or a method, as disclosed in this application disclosure.

In view of an aspect of the state of the art, a problem to be addressed is how to provide an improved manner of identifying and/or visualizing and/or controlling an internal state of a pump during operation so as to improve the pumping process in a pump. This problem is addressed by examples, such as by a method and/or a system and/or a pump, as disclosed in this disclosure.

In view of an aspect of the state of the art, a problem to be addressed is how to provide an improved manner of identifying and/or visualizing and/or controlling an internal state of a pump during operation so as to control physical parameters exhibited in a fluid system coupled to receive fluid from the pump and/or so as to improve performance of the fluid system that receives fluid from the pump during operation of the pump.

This problem is addressed by examples, such as by a method and/or a system and/or a pump, as disclosed in this disclosure.

According to an aspect of this disclosure, this problem may be addressed by providing a linearized model of the pumping process of the pump and fluid system combination, the model being linearized at an operating point.

In view of an aspect of the state of the art, a problem to be addressed is how to enable delivery of a variable fluid flow and pressure while reducing or eliminating unfavourable centrifugal pump operating conditions.

This problem is addressed by examples, such as by a method and/or a system and/or a pump, as disclosed in this disclosure. In view of an aspect of the state of the art, a problem to be addressed is how to provide an improved manner of identifying an internal state of a pump during operation.

This problem is addressed by appended claim 11 and example 253: A method for monitoring and/or operating a centrifugal pump (10; 10A; 10B; 10C; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20), having a first number (L) of vanes (310), is disposed for urging a fluid material (30) via the volute to a pump outlet (66) which is coupled to a fluid system (52) via a valve arrangement (V_L; V_H ), the method comprising: receiving, by an apparatus (150, 150A, 450), a measuring signal indicative of a fluid pressure pulsation (PFP) in the fluid material (30); receiving, by said apparatus (150, 150A, 450), a reference signal indicative of a rotational reference position of said rotating impeller; generating, by said apparatus (150, 150A, 450), data (XI ; X2; X3; X4) indicative of an internal state (X) of the centrifugal pump, said data including a phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)) based on a temporal relation between a repetitive reference position signal value (Ps, Pc, 1, 1C) and a repetitive signal event signature (Sp(r); Sp) whose repetition frequency (F_R) depends on said first number (L) when said first number (L) is higher than one;

Example 258. The method according to any of examples 252-257, wherein said phase value (FI, FI(r), Xl(r)) is indicative of a current operating point of the pump in relation to a Best Efficiency Point of operation, and/or wherein said temporal relation value (FI, FI(r), Xl(r)) is indicative of a current operating point of the pump in relation to a Best Efficiency Point of operation.

Example 254. The method according to any preceding example or the method according to any of examples 252 or 253 or the method according to any preceding example when dependent on any of examples 201 to 251, further comprising the steps: generating at least one set point parameter (UISP, U2SP) based on said phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)); wherein said at least one set point parameter (UISP, U2_SP) comprises a rotation speed set point value (UISP, f_ROTSP) for controlling a rotational speed (Ul, f_ROT) of the impeller (20).

An embodiment 12 and Example 259. The method according to any of examples 252-258, wherein said rotation speed set point value (UISP, f_ROTSP) affects pump outlet fluid pressure (Yl, P54) and/or pump outlet fluid flow (Y2, Q_OUT) at said pump outlet (66), and wherein said rotation speed set point value (U 1 SP, f_ROTSP) is based on a desired system delivery flow (YI OREF, Q_OUTSREF) and on said phase value (FI, FI(r), Xl(r)) and/or temporal relation value (FI, FI(r), Xl(r)).

An embodiment 13 and Example 261. The method according to example 256 or any of examples 255-260, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow, then said rotation speed set point value (U 1 SP, f_ROTSP) is adjusted to increase said impeller rotational speed (Ul, f_ROT).

An embodiment 14 and Example 262. The method according to example 256 or any of examples 255-261, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow, then said rotation speed set point value (U 1 SP, f_ROTSP) is adjusted to increase said impeller rotational speed (Ul, f_ROT) until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y 10_REF, Q_OUTSREF).

An embodiment 15 and Example 255. The method according to example 254 when dependent on any of examples 252-253, wherein said a valve arrangement (VL; VH) comprises a flow control valve (VL; VH) having a first adjustable cross sectional area (AVLS; AVHS) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said at least one set point parameter (UI SP, U2SP) comprises a first valve set point value (U2sp, U2Asp) for controlling said first adjustable cross sectional area (AVLS; AVHS).

An embodiment 16 and Example 256. The method according to any of examples 252-255, wherein said valve arrangement (VL; VH) comprises a first flow control valve (VLS) having a first adjustable cross sectional area (AVLS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said valve arrangement (VL; VH) comprises a second flow control valve (VLR) having a second adjustable cross sectional area (A VLR ) for controlling another flow (QR), such as for example a return flow (QR); said another flow (QR) being diverted from flowing to the fluid system (52), wherein said at least one set point parameter (Ulsp, U2sp) comprises a first valve set point value (U2SP, U2ASP) for controlling said first adjustable cross sectional area (AVLS ) and/or said second adjustable cross sectional area (AVLR ).

An embodiment 17 and Example 260. The method according to example 256 or any of examples 255-259, wherein said first valve set point value (U2SP, U2ASP) is initially set so that said system delivery flow (Y10, Q_OUTS) is equal to said pump outlet fluid flow (Y2, Q_OUT). According to an embodiment this may be achieved, for example, by simultaneously controlling said first adjustable cross sectional area (AVLS ) and said second adjustable cross sectional area (AVLR ) so as to direct all, or substantially all, of said pump outlet fluid flow (Y2, QOUT) to said fluid system (52).

An embodiment 18 and Example. 263. The method according to example 256 or any of examples 255-262, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a lower pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YI OREF, Q_OUTSREF); then said rotation speed set point value (Ulsp, fRorsp) is adjusted to increase said impeller rotational speed (Ul, f_ROT), e.g. until said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said first valve set point value (U2SP, U2ASP) is adjusted so as to increase said another flow (QR). In this manner, for example, an oversized pump that was running at a speed of revolution below BEP flow is operated to increase pump outlet fluid flow (Y2, QOUT), thereby advantageously allowing the pump to run at a more energy efficient point of operation 205 at or near BEP flow, and a surplus flow, i.e. a difference between pump outlet fluid flow at BEP (Y2BEP, Q_OUTBEP) and the system delivery flow (Y10, Q_OUTS), may be directed as a return flow.

An embodiment 19 and Example 264. The method according to example 256 or any of examples 255-263, wherein when said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) with pump outlet flow (Y2, QOUT) at, or substantially at, Best Efficiency Point of pump outlet flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YI OREF, Q_OUTSREF); then said first valve set point value (U2SP, U2ASP) is adjusted so as to minimize, or eliminate, said another flow (QR).

This is advantageously done in order to minimize return flow (QR). However, when the first valve set point value (U2SP, U2ASP) is adjusted so as to minimize, or eliminate, said another flow (QR), then this may lead to a higher system delivery flow (Y10, Q_OUTS).

An embodiment 20 and Example 265. The method according to example 256 or any of examples 255-264, wherein when said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) with a flow at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is higher than to a desired system delivery flow (YIOREF, Q_OUTSREF); then said rotation speed set point value (U ISP, f_ROTSP) is adjusted to decrease said impeller rotational speed (U 1 , f_ROT), e.g. until said system delivery flow (Y 10, Q_OUTS) corresponds to a desired system delivery flow (YI OREF, Q_OUTSREF).

An embodiment 21 and Example 266. The method according to any preceding example or according to example 254 when dependent on any of examples 252-253, wherein said valve arrangement (VL; VH) comprises a flow control valve (VH) having a third adjustable cross sectional area (AVHS) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said at least one set point parameter (U I SP, U2SP) comprises a second valve set point value (U2SP, U2BSP) for controlling said third adjustable cross sectional area (AVHS ).

An embodiment 22 and Example 267. The method according to example 266 or any of examples 255-262, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a higher pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), then said second valve set point value (U2SP, U2BSP) is adjusted so as to reduce said third adjustable cross sectional area (AVHS).

It is noted that a reduction of the third adjustable cross sectional area (AVHS ) will cause a reduced pump outlet fluid flow (Y2, QOUT) and an increased pump outlet fluid pressure (Yl, P54). In this manner, for example, a pump that was running at back pressure Yl below BEP back pressure (YI BEP) is operated to increase pump outlet fluid pressure (Yl, P54), thereby advantageously allowing the pump to run at a more energy efficient point of operation 205 at or near BEP pressure (Y I BEP), and a surplus pressure, i.e. a difference between pump outlet fluid pressure (Y 1 , P54) at BEP (Y 1 BEP) and the system delivery Head (Ps4s), is exhibited as a pressure difference across the flow control valve (VH).

However, it is noted that the resulting reduced pump outlet fluid flow (Y2, QOUT) may render a system delivery flow (Y10, Q_OUTS) to the fluid system (52) that is lower than a desired system delivery flow (Y I OREF, Q_OUTSREF).

An embodiment 23 and Example 268. The method according to example 256 or any of examples 255-264, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a flow at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is lower than to a desired system delivery flow (YI OREF, Q_OUTSREF); then said rotation speed set point value (U 1 SP, firoTSp) is adjusted to increase said impeller rotational speed (Ul, f_ROT), e.g. until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF). An embodiment 24 and Example 269. The method according to any preceding example, wherein said phase value (FI, FI(r), Xl(r)) is a temporal relation value (FI, FI(r)).

An embodiment 25 and Example 271. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point deviation (FIDEV; FIDEV(P+1); 550(p+l )) from a Best Efficiency Point of operation of the centrifugal pump (10).

An embodiment 26 and Example 272. The method according to any preceding example, further comprising displaying, on a user interface, said at least one set point parameter (UISP, U2SP; U2ASP; U2BSP) as a suggestion to a user.

An embodiment 27 and Example 274. The method according to any preceding example when including example 254, wherein said at least one set point parameter (U 1 SP, U2SP; U2ASP; U2BSP) is based on a desired temporal relation value (FIREF, FIREFG-), XI REF), said desired temporal relation value (FIREF, FlREF(r), XI REF) being indicative of a desired pump operating point (205REF, 550 REF; XIREF (r))-

An embodiment 28 and Example 275. The method according to any preceding example when including example 254, wherein said rotation speed set point value (UISP, f_ROTSP) is based on a desired impeller rotational speed (U 1 REF, f_ROTREF, X3REF).

An embodiment 29 and Example 276. The method according to any preceding example when including example 254, wherein said rotation speed set point value (U I SP, f_ROTSP) is based on a desired impeller rotational speed (UIREF, f_ROTREF, X3REF), said desired impeller rotational speed (UI REF, fROTREF, X3REF) being indicative of a desired flow (Y2REF, QOUT_REF, Q_OUTS_REF) and/or a desired Head (Y I REF, P54REF). An embodiment 30 and Example 277. The method according to any preceding example, wherein adjusting the first valve set point value (U2SP, U2ASP) occurs during operation of the pump.

An embodiment 31 and Example 278. The method according to any preceding example, wherein adjusting the second valve set point value (U2SP, U2BSP) occurs during operation of the pump.

An embodiment 32 and Example 257. The method according to any of examples 252-256, wherein the another flow (QOUTR) is a return flow for returning fluid to a fluid storage or to an inlet side of the pump (10).

The above problem is also addressed by appended claim 50 and example 279. A computer program, loadable into a digital memory of an apparatus (150) having a data processor (350), the computer program comprising computer program code (380, 394, 410) adapted to perform the steps of the method according to any preceding example when said computer program is run on a data processor.

An embodiment 51 and Example 280. The computer program according to example 279, the computer program being embodied on a computer readable medium.

The above problem is also addressed by appended claim 52 and example 281. An apparatus for monitoring and/or operating a centrifugal pump (10) and/or a fluid system (52), the apparatus being configured to perform the method according to any preceding example.

An embodiment 51 and Example 282. The apparatus according to claim 281, further comprising one or more hardware processors configured to perform the method according to any preceding example. Brief Description of the Drawings

For simple understanding of the present invention, it will be described by means of examples and with reference to the accompanying drawings, of which

Figure 1A shows a somewhat diagrammatic and schematic side view of a system including a centrifugal pump.

Figure IB shows another somewhat diagrammatic and schematic side view of a system including a centrifugal pump.

Figure 2A is an illustration of a centrifugal pump 10.

Figure 2B is a plot illustrating the operating point of the pump of FIG. 2A.

Figure 2C is a block diagram illustrating a centrifugal pump as a box 10B receiving a number of inputs Ul, ... Uk.

Figure 2D is an illustration of an example of a centrifugal pump 10.

Figure 2E is an illustration of yet another example of a centrifugal pump 10.

Figure 3 is a schematic block diagram of an example of the analysis apparatus 150 shown in Fig 1.

Figure 4 is a simplified illustration of the program memory 360 and its contents.

Figure 5 is a block diagram illustrating an example of the analysis apparatus 150.

Figure 6A is an illustration of a signal pair S(i) and P(i) as delivered by the A/D converter 330.

Figure 6B is an illustration of a sequence of the signal pair S(i) and P(i) as delivered by the A/D converter 330.

Figure 7 is a block diagram that illustrates an example of a part of a status parameter extractor 450.

Figure 8 is a simplified illustration of an example of the memory 460 and its contents.

Figure 9 is a flow chart illustrating an example of a method of operating the status parameter extractor 450 of Figure 7.

Figure 10 is a flow chart illustrating an example of a method for performing step S#40 of

Figure 9.

Figure 11 is a flow chart illustrating another example of a method.

Figure 12 is a flow chart illustrating an example of a method for performing step S#40 of Figure 9. Figure 13 is a graph illustrating a series of temporally consecutive position signals, each position signal being indicative of a full revolution of the monitored impeller.

Figures 14A, 14B and 14C show another example of a cross-sectional view of the pump during operation.

Figures 14D, 14E and 14F illustrate another aspect of flow and pressure patterns in a pump. Figure 14G is another illustration of the example pump 10 of any of figures 1 A, IB, 2A, 2B, 2D, 2E or any of 14A to 14F.

Figure ISA is a block diagram illustrating an example of a status parameter extractor 450. Figure 15B is a block diagram illustrating another example of a status parameter extractor. Figure 16 is an illustration of an example of a visual indication of an analysis result.

Figures 17 and 18 are illustrations of another example of a visual indication of an analysis result.

Figure 19A is an illustration of yet another example of a visual indication of an analysis result in terms of internal status of the centrifugal pump 10.

Figures 19B, 19C and 19D are illustrations of a large number of internal status indicator objects relating to a pump that has operated at flow below BEP as well as at flow over BEP. Figure 19E is an illustration of a first time plot of the amplitude of a detected fluid pressure pulsation in a centrifugal pump having four impeller vanes.

Figure 19F is another illustration of a second time plot of the amplitude of a detected fluid pressure pulsation in the same centrifugal pump as discussed in connection with Figure 19E. Figure 20 is a block diagram of an example of a compensatory decimator.

Figure 21 is a flow chart illustrating an embodiment of a method of operating the compensatory decimator of Figure 20.

Figures 22A, 22B and 22C illustrate a flow chart of an embodiment of a method of operating the compensatory decimator of Figure 20.

Figure 23 is a block diagram that illustrates another example of a status parameter extractor. Figure 24 illustrates a pump having an adaptive volute and a sensor.

Figure 25A shows another example system including a pump having an adaptive volute and a sensor.

Figure 25B is a sectional top view of the pump shown in figure 25A.

Figure 26 shows a somewhat diagrammatic and schematic view of yet another embodiment of a system including a pump having an adaptive volute and a sensor.

Figure 27 shows a schematic block diagram of a distributed process monitoring system. Figure 28 shows a schematic block diagram of yet another embodiment of a distributed process monitoring system.

Figure 29 shows a schematic block diagram of yet another embodiment of a distributed process control system.

Figure 30A shows an interpretation of a repetitive flow pattern in a centrifugal pump when the pump operates at a flow lower than BEP flow.

Figure 30B shows a tongue, an axis of impeller rotation, and a line from a tip of tongue and the axis of impeller rotation.

Figure 30C shows a sectional side view, section B-B of the pump as shown in figure 30B.

Figure 31 shows a block diagram illustrating a centrifugal pump as a box receiving a number of inputs Ul, ... Uk, and generating a number of outputs Yl, ... Yn.

Figure 32 shows a block diagram of a system including a centrifugal pump illustrated as a box receiving a number of inputs Ul, ... Uk, and generating a number of outputs Yl, ... Yn.

Figure 33 shows a block diagram of a system including a centrifugal pump illustrated as a black box receiving a number of inputs U 1 , ... Uk, and generating a number of outputs Y 1 , ... Yn.

Figure 34 shows a somewhat diagrammatic view of a system including a centrifugal pump.

Figure 35 shows a schematic general overview of information that may be conveyed by input/output interface of Figure 34.

Figure 36A shows a schematic block diagram of an embodiment of a process monitoring system.

Figure 36B shows the valve arrangement of figure 36A in more detail.

Figure 37 shows plot of a large number of successive pairs of vector values.

Figure 38 shows an example plot of a generated linear regression result.

Figure 39 shows a block diagram of a system for monitoring of an internal state of a pump and for providing improved information content to an operator of the pump.

Figure 40 shows a block diagram of a system for monitoring of an internal state of a pump and for enabling improved control of a pumping process that occurs in the pump.

Figure 41 shows a graph illustrating an example of a dependence of an amplitude relation value of a vane pass frequency.

Figure 42 shows a schematic block diagram of yet another example of a process monitoring system.

Figure 43 shows an example of a pump of liquid ring type. Figures 44 A-C shows a basic operation of a liquid ring pump.

Figure 45 shows a circular plot of velocity vibrations obtained by measurements on a specific pump.

Figure 46 shows a polar plot of velocity vibrations obtained by measurements relating to the pump of figure 45.

Figure 47 shows a polar plot of velocity vibrations obtained by measurements relating to a pump.

Detailed Description

In the following text similar features in different examples will be indicated by the same reference numerals.

Figure 1A shows a system 5 including a centrifugal pump 10 for a causing a fluid 30 to be transported, via a piping system 40, to a fluid material consumer 50. The fluid system to which the pump is coupled, including the piping system 40 and the fluid material consumer 50, is herein referred to as fluid system 52.

The fluid 30 may comprise fiber slurry 30A for paper production in a paper-making machine used in the pulp and paper industry to create paper in large quantities at high speed. The fluid material consumer 50 may include a headbox 50A, also referred to as head tank, whose purpose is to maintain a constant head (i.e. constant pressure) on the fiber slurry 30A. The fluid material consumer 50 may include a basis weight valve (not shown) whose purpose is to modulate the flow of fluid 30A as it is mixed with white water on its way to the head box 50A, as well as forming wire where a paper sheet begins to take shape. The basis weight of paper is calculated by the weight per a given unit area. Production of high quality paper requires precise control of the basis weight valve. Fluctuations in paper layer thickness or basis weight of the paper can result in uneven drying, a poor finished product and/or waste since such fluctuations may require rejection of the produced paper. Thus, it is desired to achieve a constant flow QOUT, as delivered from the centrifugal pump 10 so as to enable the production of high quality paper.

In the field of fluid dynamics, Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy. Thus, when a volume of fluid is flowing horizontally from a first region 54 of high pressure to a second region 56 of low pressure, then there is more pressure behind than in front. This gives a net force on the volume, accelerating it along the streamline. In the example illustrated in figure 1, the piping system 40 leading the fluid 30 from the first region 54 of high pressure to the second region 56 of low pressure includes a piping component 58 that may include a filter 58 A.

Bernoulli's principle, for a volume of fluid flowing horizontally at a speed v from a first region 54 of high pressure PH to a second region 56 of low pressure PL, can be expressed in mathematical terms as follows:

Where

P = Pressure in the fluid material, D= Density of the fluid material v= the speed at which the fluid material flows

Thus, with reference to figure 1, when applying Bernoulli's principle to a volume of fluid flowing horizontally at a speed V54 in a first region 54 of higher pressure P54 to a second region 56 of lower pressure P56, the fluid will flow at a speed V56 in the second region 56, as indicated by equation 2 below:

Where

P54 = Pressure in the fluid material in first region 54, D= Density of the fluid material

V54= the speed at which the fluid material flows in first region 54 P56 = Pressure in the fluid material in second region 56, V56= speed at which the fluid material flows in second region 56

A centrifugal pump controller 240 may be configured to deliver an impeller speed set point value UISP, fROTSP so as to control the rotational speed f_ROT of the impeller 20. A user interface 250 for input/output from/to a pump operator 230 (See Figure 1 A), is coupled to the regulator 240. According to some embodiments, the set point value is set by an

operator 230 via the user interface 250. In this manner an operator 230 may operate the pump 10.

Figure IB shows another somewhat diagrammatic view of a system 325 including a centrifugal pump 10. Thus, reference numeral 325 relates to a system including a pump 10 having a rotatable impeller 20, as discussed in this document. The system 325 of figure IB may include parts, and be configured, as described above in relation to figures 1A and 2A and/or as described elsewhere in this document.

Whereas the pump user input/output interface 250, in the example illustrated in Figure 1 A, is coupled to the regulator 240 and the HCI 210 is a separate input/output interface coupled to the analysis apparatus 150, or monitoring module 150A, the system illustrated in Figure IB may provide an integrated HCI 210, 250, 210S. Thus, the input/output interface 210 of Figure IB may be configured to enable all the input and/or output described above in conjunction with interfaces 210 and 250.

Figure 2A is an illustration of an example of a centrifugal pump 10. The pump 10 comprises a casing 62 in which a rotatable impeller 20 is disposed so that it can rotate around an axis of rotation 60. The casing 62 defines a pump inlet 64 for fluid material 30 and an outlet 66 for the fluid material 30. The casing also defines a volute 75. The volute 75 may be a curved funnel that increases in cross sectional area as fluid material 30, flowing therein, approaches the outlet 66, which may also be referred to as a discharge port 66.

The volute 75 of a centrifugal pump 10 is that part of the casing that receives the fluid 30 being pumped by the impeller 20. The impeller 20 has a number L of vanes 310 for urging, when the impeller 20 rotates, the fluid material 30 from the pump inlet 64 into the volute 75. The example impeller shown in figure 1, has 6 vanes 310. The vanes 310 define a number of impeller passages 320 for causing the fluid material 30 to flow from the pump inlet 64 into the volute 75. In other words, the L vanes 310 define L impeller passages 320, the number L being L=6 in the example illustrated in figure 2A.

The casing 62 has an outlet portion 63 separating a first part 77 of said volute 75 from a second part 78 of the volute. The first volute part 77 has a first, smaller, cross sectional area, and the second volute part 78 has a second, larger, cross sectional area. The outlet portion of the pump illustrated in figure 2A has a volute tongue 65. A sensor 70, 70₇₈ of example pump 10 of figure 2A may be attached to the casing 62 at the second volute part 78 by the larger cross sectional area near the outlet 66 of the pump 10.

As the fluid travels along the volute it is joined by more and more fluid 30 exiting the rotating impeller passages 320 but, as the cross sectional area of the volute increases, the velocity v75 is maintained if the pump is running close to the flow QOUT for which the pump was designed. In this manner, the fluid 30 is forced to exit the pump outlet 66 thereby causing a fluid material flow QOUT from the outlet 66. In this context, the “flow QOUT for which the pump was designed” may also be referred to as the flow Q_OUTBEP which is the flow at the Best Efficiency Point (BEP) of the pump.

The flow QOUT for which the pump was designed, i.e. the design flow, may also be referred to as the design point, or design operating point. The design point is often referred to as the Best Efficiency Point, BEP, of operation. Referring to figure 2A, the volute 75 increases in cross sectional area as fluid material 30, flowing therein, approaches the outlet 66. The volute receives fluid from the impeller passages 320, maintaining the velocity V75 of the fluid in the volute at a constant value during operation at design operating point. This is because, as the fluid travels along the volute 75 it is joined by more and more fluid, received from the impeller passages 320, but since the cross-sectional area of the volute increases, the velocity V75 is maintained when the pump operates at design operating point.

However, if the pump has a low flow rate then the fluid velocity V75 will decrease along the volute, and fluid pressure will increase along the volute. Conversely, if the pump flow is higher than design, the fluid velocity will increase across the volute and the pressure will decrease. This is a consequence of the continuity equation, and it follows from Bernoulli's principle. It is also consequence of the first law of thermodynamics.

Figure 2B is a plot illustrating an operating point 205 of the pump of FIG. 2A in a flow versus pressure diagram. Referring to figure 2B and figure 1 and/or 1 B, the operating point 205 of the pump 10 is indicated by the intersection of a pump curve 207 and the system curve 209 of the particular system 52, 40, 50 to which the pump outlet 66 is connected (See figure 2B in conjunction with figure 1 A and/or figure IB). The pump curve 207 indicates how the pump pressure will change with flow. In a fluid system 52, 40, 50 that fluctuates in pressure and flow over time, the system curve 209 changes over the lifetime and operation of the system 52. Accordingly, the operating point 205 of the pump 10 can move along the pump curve 207. When the operating point 205 moves away from the best efficiency point, BEP, there is typically an increase in fluid pressure pulsations.

Pressure pulsations are fluctuations in the fluid pressure. During operation, the centrifugal pump may cause such pressure pulsations. Some pressure pulsations are fluctuations in the fluid pressure being developed by the pump at the pump outlet 66. Thus, the fluid 30 exiting the pump outlet 66 may exhibit a fluid material flow QOUT with a pressure pulsation PFP (See figure 2A). The fluid pressure pulsation Ppp has a repetition frequency fR dependent on a speed of rotation f_ROT of the impeller 20.

Referring to figure 2A, a sensor 70 may be provided for generating a measuring signal SEP, SEA, SMD, Se(i), S(j), S(q) dependent on the fluid material pressure pulsation PFP. The sensor 70 may be configured for generating the measuring signal SFP, SEA, SMD, Se(i), S(j), S(q) dependent on the fluid material pressure pulsation PFP caused by the pump during operation. Referring to figure 2A, the sensor 70 may be mounted on the casing 62. Alternatively the sensor may be mounted to a pipe or fluid conduit for transporting pumped fluid from the pump outlet 66.

A sensor 70 may, for example, be embodied by an accelerometer. An example of an accelerometer includes a Micro Electro-Mechanical System, abbreviated MEMS. Accordingly, a sensor 70 may include a semiconductor silicon substrate configured as a MEMS accelerometer.

A sensor 70 may alternatively be embodied by a piezo-electric accelerometer. Alternatively, a sensor 70 may be embodied by piezoresistive sensor 70. A piezoresistive sensor 70 may operate as a strain gauge configured to measure stress. A piezoresistive sensor 70 may include a piezoresistive material configured to be deformed when a force is applied to it, the deformation causing a change in the sensor resistance.

Yet another example of sensor 70 is a velocity sensor. A velocity sensor 70 includes a coil and magnet arrangement configured to measure velocity. Alternatively, the sensor 70 may be a strain gauge. Thus, the strain gauge 70 is attachable to the pump casing 62 or to the pump outlet pipe 54 for generating the measuring signal indicative of fluid pressure pulsation PFP. The strain gauge may be configured to generate said measuring signal based on deformation, caused by fluid pressure pulsation PFP, of said pump casing 62 or of said pump outlet pipe 54. It is noted that a strain gauge is a device that can be used for measuring strain on an object, such as a pipe 54 or a pump casing 62. An example of a strain gauge 70 comprises an electrically conducting foil forming a conductor having electrical resistance that changes when the conductor is elongated or contracted. Thus, the inventor realized that the fluid pressure pulsation PFP may cause deformation of said pump casing 62 or of said pump outlet pipe 54. Such deformation causes a change of the electrical resistance, which is detectable for generating the measuring signal indicative of the fluid pressure pulsation PFP. The change of the electrical resistance may be measured using a Wheatstone bridge. In this connection it is noted that the resistance change is related to the strain by a quantity known as the gauge factor.

According to another example, the sensor 70 may be a pressure sensor 70 for generating a measuring signal dependent on fluid pressure pulsation PFP in the fluid 30. The pressure sensor may be mounted so as to detect a fluid pressure pulsation PFP in said fluid material 30. The pressure sensor 70 may, for example, be embodied by a commercially available sensor sold under the brand ICP® PRESSURE SENSOR, Model 121A41.

Accordingly, in methods described in this disclosure, the measuring signal SFP; SEA, SMD, Se(i), S(j), S(q) indicative of fluid pressure pulsation may be generated by a vibration sensor configured to generate said measuring signal based on vibration VFP exhibited by said pump; and/or by a strain gauge configured to generate said measuring signal based on deformation, caused by fluid pressure pulsation PFP, of a pump casing 62 or of a pump outlet pipe 54; and/or by a pressure sensor configured to detect a fluid pressure pulsation PFP, P54 in said fluid material 30.

The pump may also be also provided with a position sensor 170 for generating a position signal EP, PS, P(i), P(j), P(q) indicative of a rotational position of said impeller 20 in relation to the casing 62. As shown in Figure 2A, a position marker device 180 may be provided in association with the impeller 20 such that, when the impeller 20 rotates around the axis of rotation 60, the position marker 180 passes by the position sensor 170 once per revolution of the impeller, thereby causing the position sensor 170 to generate a revolution marker signal value PS.

Whereas figure 2A illustrates that a single position marker 180 may be provided in association with the impeller 20, the position marker 180 thereby causing the position sensor 170 to generate a revolution marker signal value Ps once per revolution, it is noted that position signal values Ps, Pc may alternatively be generated more than once per revolution. For example, position signal values PS, Pc may be generated more than once per revolution by providing more than one position marker 180 in association with the impeller 20. Alternatively, position signal values Ps, Pc may be generated by an encoder 170 which is mechanically coupled to the rotating pump impeller 20. Thus, the position sensor 170 may be embodied by an encoder 170 which is mechanically coupled to the rotating pump impeller 20 such that the encoder generates e.g. one marker signal Ps per vane 310 in the rotating impeller 20 during rotation of the impeller 20. In this manner, the encoder 170 may deliver L marker signals Ps per revolution of the impeller 20.

Alternatively, the position sensor 170 for generating a position signal EP, PS, P(i), P(j), P(q) may include a light source 170, such as e.g. a laser, in combination with a light detector 170 that cooperates with position marker device 180 in the form of a reflective tape 180 on a rotating part.

Alternatively, the position sensor 170 for generating a position signal EP, PS, P(i), P(j), P(q) may include an inductive probe 170 that is configured to detect the presence of a metal or magnetic part 180 on the rotating shaft. The metal or magnetic part 180 may be embodied e.g. by a bolt, or a wedge. The inductive probe 170 position detector is advantageously efficient also in dirty environments. Yet another example of position sensor 170 and position marker device 180 arrangement includes a Hall effect sensor 170 that cooperates with a magnet 180 mounted on a rotating part. The Hall effect sensor 170 is advantageously insensitive to dust and dirt.

As regards physical location of the position sensor 170 and position marker device 180 arrangement, the following may be considered: When there is risk for torsional movement of a rotating shaft, for example if the shaft is too weak compared with the torque it may be preferable to mount the position marker device 180 as close as possible to the impeller 20 so as to avoid adverse effects on the measurements by the torsional movement.

Although the above example relates to pulp, the fluid to be pumped by a pump 10 may be any fluid material 30. The fluid material 30 may be water. Water has a density of about 997 kg per cubic metre. Sometimes the fluid to be pumped includes pieces of solid material. For example, the fluid material 30 may comprise a mixture of water and solids denser than water , such as sand or crushed rock material, also referred to as slurry.

A slurry is a mixture of solids denser than water suspended in liquid. The pieces of solid material may have a density that differs from the density of water. Moreover, sometimes the compressibility of the fluid material 30 differs from that of water.

The fluid material 30 may alternatively be an oil.

Table 1 provides some examples of fluid materials and example solid materials that may be suspended in the fluid 30. Table 1 also provides some material properties, including density.

Table 1

The outlet of the centrifugal pump 10 may include, or be coupled to, a filter 58 (See figure 1 in conjunction with figure 2A).

It is desirable to obtain a high degree of efficiency of the pumping process. One aspect of pumping process efficiency is the amount of pulsation in the flowing material 30 leaving the pump 10. Hence, it is desirable to maximize the flow QOUT of fluid material from a pump while minimizing pulsation in the pumped fluid.

The efficiency of the pumping process in a centrifugal pump 10 depends on a number of variables affecting the internal state of the centrifugal pump 10. One variable that has an impact on the efficiency of the pumping process in a centrifugal pump 10 is the operating point of the centrifugal pump 10. Hence, it is desirable to control the operating point so as to achieve an optimal pumping process.

In order to maximise the amount of output material from the centrifugal pump 10 it is therefore desirable to maintain an optimal state of the centrifugal pump process.

In this context it is noted that centrifugal pump power consumption per pumped volume increases when the centrifugal pump 10 operates away from BEP.

Another variable that has an impact on the efficiency of the pumping process in a centrifugal pump 10 is the system pressure, also referred to as backpressure. The backpressure of the system may vary e.g. if there is a valve in the flow path of the piping system 40 (See figure 1). Alternatively, the backpressure of the system may vary when the piping system 40 includes a filter 58, that can exhibit a varying degree of clogging. Clogging of filter 58 may occur as a consequence of particles that are caught in the filter, thereby gradually reducing the cross sectional effective flow area through the filter 58. An increased clogging therefore leads to a reduced effective flow area which in turn leads to a higher pressure drop over the filter 58. In this connection, it is noted that some fluids 30, such as slurry or pulp, may exhibit properties that are not constant over time, since the composition of some fluid material 30, such as slurry or pulp, may vary over time. The variation of the properties of the fluid material 30 may affect the efficiency of the pumping process of the centrifugal pump 10. Hence, the efficiency of the pumping process may be variable over time.

Referring to figures 1 A and IB, the system 5, 325 may include a control room 220 allowing a pump operator 230 to operate the centrifugal pump 10. The analysis apparatus 150 may be configured to generate information indicative of an internal state of the centrifugal pump 10. The analysis apparatus 150 also includes an apparatus Human Computer Interface (HCI) 210 for enabling user input and user output. The HCI 210 may include a display, or screen, 210S for providing a visual indication of an analysis result. The analysis result displayed may include information indicative of an internal state of the centrifugal pump process for enabling the operator 230 to control the centrifugal pump.

A centrifugal pump controller 240 may be configured to deliver an impeller speed set point value UI SP, f oTSP so as to control the rotational speed f_ROT of the impeller 20. According to some embodiments, the set point value U I SP, f_ROTSP is set by the operator 230.

The pump user input/output interface 250, in the example illustrated in Figure 1A, is coupled to the regulator 240 and the HCI 210 is coupled to the analysis apparatus 150, or monitoring module 150A, configured to generate information indicative of an internal state of the centrifugal pump 10. Thus, when coupled only to monitoring module 150A as shown in figure 1A, the HCI 210 is advantageously possible to add, in a control room 220, without any need to modify any previously existing input/output interface 250 and regulator 240 used by a pump operator 230 to operate the centrifugal pump 10.

An object to be addressed by solutions and examples disclosed in this document is to describe methods and systems for an improved monitoring of an internal state X in a centrifugal pump 10 during operation. It is also an object, to be addressed by solutions and examples disclosed in this document, to describe methods and systems for an improved control of an internal state X in a centrifugal pump 10 during operation. Moreover, an object to be addressed by solutions and examples disclosed in this document is to describe methods and systems for an improved Human Computer Interface (HCI) relating to conveying useful information about the internal state X in a centrifugal pump during operation. Another object to be addressed by this document is to describe methods and systems for an improved Graphical User Interface relating to the pumping process in a centrifugal pump 10.

When the pump 10 is coupled to a fluid system 52, some aspects of the fluid system 52 may be affected by the internal state X of the pump. For example, if the pump delivers a fluid flow that exhibits a pulsation, such pulsation may cause resonance in some part of the fluid system 52. According to some examples, some aspects of a fluid system 52 can be measured or estimated in terms of parameters Yl, Y2, Y3, ... Yn, describing such aspects of the fluid system 52.

Thus, an object to be addressed by some solutions and examples disclosed in this document is to describe methods and systems for an improved control of parameters Y 1 , Y2, Y3, ... Yn relating to the fluid system 52.

Yet another object to be addressed by solutions and examples disclosed in this document is to describe methods and systems for an improved Human Computer Interface (HCI) relating to conveying useful information about a parameter Yl, Y2, Y3, ... Yn relating to the fluid system 52 during operation of the centrifugal pump 10.

In this connection it may also be an object to be addressed by solutions and examples disclosed in this document to convey useful information about a parameter Yl, Y2, Y3, ... Yn relating to the fluid system 52 during operation of the centrifugal pump 10 while also conveying useful information about a corresponding internal state X in the centrifugal pump 10 during operation.

Figure 2C is a block diagram illustrating a centrifugal pump as a box 10B receiving a number of inputs Ul, ... Uk, causing the pump to have an internal state X. The internal state X of the pump may be described, or indicated, by a number of internal state parameters XI, X2, X3,..., Xm, where the index m is a positive integer. An individual internal state parameter, such as XI, X2, X3 or Xm, may be a value which is indicative of an aspect the internal state X of the pump 10.

Similarly, one or several aspects Y of the system 52 to which the pump 10 is coupled may be monitored. Thus, a system 52 coupled to receive fluid from a pump 10 may exhibit a system state Y that can be described by a number of parameters Y 1 , Y2, Y3, ... Yn, where the index n is a positive integer. Thus, the output parameters Y 1 , Y2, Y3, ... Yn are indicative of the state in the fluid system 52 (See figure 2C in conjunction with e.g. figure 1 A). An individual output parameter, such as Yl, Y2, Y3, or Yn, may be a value which is indicative of an aspect the state Y of the fluid system,.

With reference to figure 2C it is noted that, for the purpose of analysis, a centrifugal pump 10 may be regarded as a black box 1 OB having a number of input variables, referred to as input parameters Ul, U2, U3, ... Uk, where the index k is a positive integer.

Using the terminology of linear algebra, the input variables Ul, U2, U3,... Uk may be collectively referred to as an input vector U; the internal state parameters XI, X2, X3,..., Xm may be collectively referred to as an internal state vector X; and the output parameters Y 1 , Y2, Y3, ... Yn may be collectively referred to as an output vector Y.

The internal state X of the pump 10, at a point in time termed r, can be referred to as X(r). That internal state X(r) can be described, or indicated, by a number of parameter values, the parameter values defining different aspects of the internal state X(r) of the pump 10 at time r. The internal state X(r) of the black box centrifugal pump 10B depends on the input vector U(r), and the output vector Y(r) depends on the internal state vector X(r).

Thus, during operation of the pump 10, the internal state X can be regarded as a function of the input U:

X = fi(U), wherein

X denotes the internal state of the pump 10; and U denotes the input vector to the pump 10

Likewise, the output Y of the black box 10B can be regarded as a function of the internal state X:

Y = f₂(X)

Figure 2D is an illustration of an example of a centrifugal pump 10. The pump 10 of figure 2D may include parts, and be configured, as described above in relation to figures 1 A and 2 A and/or as described elsewhere in this document. However, the example centrifugal pump 10 of figure 2D may include a sensor 70, 70?? attached to the casing 62 at the first volute part 77 by the narrower cross sectional area near the tongue 65.

Thus, whereas the example pump of figure 2A has a sensor 70₇₈ attached to the casing 62 at the second volute part 78 by the larger cross sectional area near the outlet of the pump, the example pump of figure 2D also has a sensor 70?7 attached to the casing 62 at the first volute part 77 by the narrower cross sectional area near the tongue 65. Alternatively, the sensor 70?? attached to the casing 62 at the first volute part 77 replaces the sensor 70??.

One or several sensors 70 may be placed so as to detect vibrations emanating from fluid pressure pulsations PFP that depend on a speed of rotation fROT of the impeller 20.

Figure 2E is an illustration of another example of a centrifugal pump 10. The pump of figure 2E has a casing comprising a number fixed vanes 312 which are positioned between said volute 75 and said impeller 20.

Figure 3 is a schematic block diagram of an example of the analysis apparatus 150 shown in Fig 1. The analysis apparatus 150 has an input 140 for receiving the analogue vibration signal SEA, from the vibration sensor 70. The input 140 is connected to an analogue- to-digital (A/D) converter 330. The A/D converter 330 samples the received analogue vibration signal SEA with a certain sampling frequency fs so as to deliver a digital measurement data signal SMD having said certain sampling frequency fs. The amplitude of a sample value delivered by the A/D converter 330 depends on the amplitude of the received analogue signal at the moment of sampling. The digital measurement data signal SMD is delivered on a digital output 340 which is coupled to a data processing device 350.

With reference to Figure 3, the data processing device 350 is coupled to a computer readable medium 360 for storing program code. A computer readable medium 360 may also be referred to as a memory 360. The program memory 360 is preferably a non-volatile memory. The memory 360 may be a read/write memory, i.e. enabling both reading data from the memory and writing new data onto the memory 360. According to an example, the program memory 360 is embodied by a FLASH memory. The program memory 360 may comprise a first memory segment 370 for storing a first set of program code 380 which is executable so as to control the analysis apparatus 150 to perform basic operations. The program memory 360 may also comprise a second memory segment 390 for storing a second set of program code 394. The second set of program code in the second memory segment 390 may include program code for causing the analysis apparatus 150 to process a detected signal. The signal processing may include processing for generating information indicative of an internal state of a centrifugal pump, as discussed elsewhere in this document. Moreover, the signal processing may include control of the internal state of a centrifugal pump, as discussed elsewhere in this document. Thus, the signal processing may include generating data indicative of an internal state of a centrifugal pump, as disclosed in connection with embodiments of status parameter extractor 450 of e.g. figure 5, 15 and/or 24.

The memory 360 may also include a third memory segment 400 for storing a third set of program code 410. The set of program code 410 in the third memory segment 400 may include program code for causing the analysis apparatus to perform a selected analysis function. When an analysis function is executed, it may cause the analysis apparatus to present a corresponding analysis result on user interface 210, 210S or to deliver the analysis result on a port 420.

The data processing device 350 is also coupled to a read/write memory 430 for data storage. Hence, the analysis apparatus 150 comprises the data processor 350 and program code for causing the data processor 350 to perform certain functions, including digital signal processing functions. When it is stated, in this document, that the apparatus 150 performs a certain function or a certain method, that statement may mean that the computer program runs in the data processing device 350 to cause the apparatus 150 to carry out a method or function of the kind described in this document.

The processor 350 may be a Digital Signal Processor. The Digital Signal Processor 350 may also be referred to as a DSP. Alternatively the processor 350 may be a Field Programmable Gate Array circuit (FPGA). Hence, the computer program may be executed by a Field Programmable Gate Array circuit (FPGA). Alternatively, the processor 350 may comprise a combination of a processor and an FPGA. Thus, the processor may be configured to control the operation of the FPGA.

Figure 4 is a simplified illustration of the program memory 360 and its contents. The simplified illustration is intended to convey understanding of the general idea of storing different program functions in memory 360, and it is not necessarily a correct technical teaching of the way in which a program would be stored in a real memory circuit. The first memory segment 370 stores program code for controlling the analysis apparatus 150 to perform basic operations. Although the simplified illustration of Figure 4 shows pseudo code, it is to be understood that the program code may be constituted by machine code, or any level program code that can be executed or interpreted by the data processing device 350 (Fig. 3).

The second memory segment 390, illustrated in Figure 4, stores a second set of program code 394. The program code 394 in segment 390, when run on the data processing device 350, will cause the analysis apparatus 150 to perform a function, such as a digital signal processing function. The function may comprise an advanced mathematical processing of the digital measurement data signal SMD.

A computer program for controlling the function of the analysis apparatus 150 may be downloaded from a server computer 830 (See fig. 27, or fig. 29). This means that the programto-be-downloaded is transmitted to over a communications network 810 (See fig. 27, or fig. 29). This can be done by modulating a carrier wave to carry the program over the communications network 810. Accordingly the downloaded program may be loaded into a digital memory, such as memory 360 (See figures 3 and 4). Hence, a program 380 and/or a signal processing program 394 and/or an analysis function program 410 may be received via a communications port, such as port 420 (Figure 1 & figure 3) or port 920 (See fig 27) or port 800B (see fig 27) or port (see fig 27), so as to load it into program memory 360.

Accordingly, this document also relates to a computer program product, such as program code 380 and/or program code 394 and/or program code 410 loadable into a digital memory of an apparatus, such as memory 360 (See figures 3 and 4). The computer program product comprises software code portions for performing signal processing methods and/or analysis functions when said product is run on a data processing unit 350 of an apparatus 150. The term "run on a data processing unit" means that the computer program plus the data processing device 350 carries out a method of the kind described in this document.

The wording "a computer program product, loadable into a digital memory of a analysis apparatus" means that a computer program can be introduced into a digital memory of an analysis apparatus 150 so as achieve an analysis apparatus 150 programmed to be capable of, or adapted to, carrying out a method of a kind described in this document. The term "loaded into a digital memory of an apparatus" means that the apparatus programmed in this way is capable of, or adapted to, carrying out a function described in this document, and/or a method described in this document. The above mentioned computer program product may also be a program 380, 394, 410 loadable onto a computer readable medium, such as a compact disc or DVD. Such a computer readable medium may be used for delivery of the program 380, 394, 410 to a client. As indicated above, the computer program product may, alternatively, comprise a carrier wave which is modulated to carry the computer program 380, 394, 410 over a communications network. Thus, the computer program 380, 394, 410 may be delivered from a supplier server to a client having an analysis apparatus 150 by downloading over the Internet.

Figure 5 is a block diagram illustrating an example of the analysis apparatus 150. In the figure 5 example, some of the functional blocks represent hardware and some of the functional blocks either may represent hardware, or may represent functions that are achieved by running program code on the data processing device 350, as discussed in connection with figures 3 and 4.

The apparatus 150 in figure 5 shows an example of the analysis apparatus 150 shown in figure 1 and/or figure 3. For the purpose of simplifying understanding, figure 5 also shows some peripheral devices coupled to the apparatus 150. The vibration sensor 70 is coupled to the input 140 of the analysis apparatus 150 to deliver an analogue measuring signal SEA, also referred to as vibration signal SEA, to the analysis apparatus 150.

Moreover, the position sensor 170 is coupled to the second input 160. Thus, the position sensor 170 delivers the position signal Ep, dependent on the rotational position of the impeller 20, to the second input 160 of the analysis apparatus 150.

The input 140 is connected to an analogue-to-digital (A/D) converter 330. The A/D converter 330 samples the received analogue vibration signal SEA with a certain sampling frequency fs so as to deliver a digital measurement data signal SMD having said certain sampling frequency fs and wherein the amplitude of each sample depends on the amplitude of the received analogue signal at the moment of sampling. The digital measurement data signal SMD is delivered on a digital output 340, which is coupled to a data processing unit 350. The data processing unit 350 comprises functional blocks illustrating functions that are performed. In terms of hardware, the data processing unit 350 may comprise a data processor 350, the program memory 360, and the read/write memory 430 as described in connection with figures 3 and 4 above. Hence, the analysis apparatus 150 of figure 5 may comprise the data processing unit 350 and program code for causing the analysis apparatus 150 to perform certain functions.

The digital measurement data signal SMD is processed in parallel with the position signal Ep. Hence, the A/D converter 330 may be configured to sample the position signal Ep simultaneously with the sampling of the analogue vibration signal SEA. The sampling of the position signal Ep may be performed using that same sampling frequency fs so as to generate a digital position signal EPD wherein the amplitude of each sample P(i) depends on the amplitude of the received analogue position signal Ep at the moment of sampling.

As mentioned above, the analogue position signal Ep may have a marker signal value Ps, e.g. in the form of an electric pulse having an amplitude edge that can be accurately detected and indicative of a certain rotational position of the monitored impeller 20. Thus, whereas the analogue position marker signal Ps has an amplitude edge that can be accurately detected, the digital position signal EPD will switch from a first value, e.g. “0” (zero), to a second value, e.g. “1” (one), at a distinct time.

Hence, the A/D converter 330 may be configured to deliver a sequence of pairs of measurement values S(i) associated with corresponding position signal values P(i). The letter “i” in S(i) and P(i) denotes a point in time, i.e. a sample number. Hence, the time of occurrence of a rotational reference position of said rotating impeller 20 can be detected by analysing a time sequence of the position signal values P(i) and identifying the sample P(i) indicating that the digital position signal EPD has switched from the first value, e.g. “0” (zero), to the second value, e.g. “1” (one).

Figure 6B is an illustration of a sequence of the signal pair S(i) and P(i) as delivered by the A/D converter 330. A first signal pair comprises a first vibration signal amplitude value S(n), associated with the sample moment “n”, being delivered simultaneously with a first position signal value P(n), associated with the sample moment “n”. It is followed by a second signal pair comprising a second vibration signal amplitude value S(n+1), associated with the sample moment “n+1”, which is delivered simultaneously with a second position signal value P(n+1), associated with the sample moment “n+1 ”, and so on.

With reference to figure 5, the signal pair S(i) and P(i) is delivered to a status parameter extractor 450. The example status parameter extractor 450 of figure 5 is configured to detect an event signature and/or generate an amplitude peak value Sp(r) based on a time sequence of measurement sample values S(i).

The status parameter extractor 450 is also configured to generate a temporal relation value RT(J), also referred to as R-r(r) or Xl(r) or FI(r), based on a temporal duration (TD) between time of occurrence of the amplitude peak value Sp(r) and time of occurrence of a rotational reference position of said rotating impeller. As mentioned above, the time of occurrence of a rotational reference position of said rotating impeller can be detected by analysing a time sequence of the position signal values P(i) and identifying a sample P(i) indicating that the digital position signal EPD has switched from the first value, e.g. “0” (zero), to the second value, e.g. “1” (one).

According to an example, the status parameter extractor 450 of figure 5 is configured to generate data, e.g. in the form of parameters XI ; X2; X3; X4, indicative of a momentary internal operating state X of the pump 10 during operation of the pump 10. This data, e.g. in the form of parameters XI ; X2; X3; X4, may also be indicative of a momentary state X of the pumping process. The status parameter extractor 450 may be configured to generate the pump internal state data XI ; X2; X3; X4 in response to a time sequence of first measuring signal sample values Se(i) and in response to a time sequence of reference position signal sample values P(i).

According to an example, the status parameter extractor 450 may be configured to detect, in the time sequence of measuring signal sample values Se(i), an event signature Sp which is repetitive with L occurrences per impeller revolution when the number L of vanes 310 on the impeller of the pump 10 is higher than one, such that said detected repetitive event signature Sp is indicative of a fluid material pressure pulsation Ppp generated when the vanes 310 interact with the fluid material 30 in the volute 75 of the pump 10.

The detection of the repetitive event signature Sp may include identifying a relevant time sequence of measuring signal sample values Se(i) based on a temporal relation between the time sequence of measuring signal sample values Se(i) and the time sequence of reference signal sample values P(i). According to an example, the time sequence of position signal sample values P(i) is indicative Ps, Pc, 1, 1C of a certain number L of stationary reference positions Ps, Pc, Pl , P2, P3, P4, P5, PL per impeller revolution; said certain number L being equal to the number of vanes 310 on the impeller of the pump 10.

Thus, the repetitive event signature may be a peak amplitude value Sp indicative of an amplitude of the fluid pulsation PFP. The peak amplitude value Sp may be used as a parameter value X2 which is indicative of an aspect of the momentary internal operating state X of the pump 10 during operation of the pump 10, and/or indicative of an aspect of the momentary state X of the pumping process.

Figure 7 is a block diagram that illustrates an example of a part of a status parameter extractor 450. According to an example the status parameter extractor 450 comprises a memory 460. The status parameter extractor 450 is adapted to receive a sequence of measurement values S(i) and a sequence of positional signals P(i), together with temporal relations there-between, and the status parameter extractor 450 is adapted to provide a sequence of temporally coupled values S(i), fROT(i), and P(i). Thus, an individual measurement value S(i) is associated with a corresponding speed value fRoi(i), the speed value f_ROT(i) being indicative of the rotational speed of the impeller 20 at the time of detection of the associated individual measurement value S(i). An example of a manner of achieving this is described in detail below with reference to figures 8-13.

Figure 8 is a simplified illustration of an example of the memory 460 and its contents, and columns #01, #02, #03, #04 and #05, on the left hand side of the memory 460 illustration, provide an explanatory image intended to illustrate the temporal relation between the time of detection of the encoder pulse signals P(i) (See column #02) and the corresponding vibration measurement values S(i) (See column #03).

As mentioned above, the analogue-to-digital converter 330 samples the analogue electric measurement signal SEA at an initial sampling frequency fs so as to generate a digital measurement data signal SMD. The encoder signal P may also be detected with substantially the same initial temporal resolution fs, as illustrated in the column #02 of Figure 8. Column #01 illustrates the progression of time as a series of time slots, each time slot having a duration dt = l/fsam_Pie; wherein fsampie is a sample frequency having an integer relation to the initial sample frequency fs with which the analogue electric measurement signal SEA is sampled. According to a preferred example, the sample frequency fsampie is the initial sample frequency fs. According to another example the sample frequency fsampie is a first reduced sampling frequency fsRi, which is reduced by an integer factor Mi as compared to the initial sampling frequency fs.

In column #02 of figure 8 each positive edge of the encoder signal P is indicated by a “1”. In this example a positive edge of the encoder signal P is detected in the 3:rd, the 45:th, the 78:th time slot and in the 98:th time slot, as indicated in column #02. According to another example, the negative edges of the positional signal are detected, which provides an equivalent result to detecting the positive edges. According to yet another example both the positive and the negative edges of the positional signal are detected, so as to obtain redundancy by enabling the later selection of whether to use the positive or the negative edge.

Column #03 illustrates a sequence of vibration sample values S(i). Column #05 illustrates the corresponding sequence of vibration sample values S(j), when an integer decimation is performed. Hence, when integer decimation is performed by this stage, it may e.g. be set up to provide an integer decimation factor M=10, and as illustrated in figure 8, there will be provided one vibration sample value S(j) (See column #05 in figure 8) for every ten samples S(i) (See column #03 in figure 8). According to an example, a very accurate position and time information PT, relating to the decimated vibration sample value S(j), is maintained by setting the PositionTime signal in column #04 to value PT = 3, so as to indicate that the positive edge (see col#02) was detected in time slot #03. Hence, the value of the PositionTime signal, after the integer decimation is indicative of the time of detection of the position signal edge P in relation to sample value S(l).

In the example of figure 8, the amplitude value of the PositionTime signal at sample i=3 is PT=3, and since decimation factor M=10 so that the sample S(l) is delivered in time slot 10, this means that the edge was detected M-PT=10-3= 7 slots before the slot of sample S(l). Accordingly, the apparatus 150 may operate to process the information about the positive edges of encoder signal P(i) in parallel with the vibration samples S(i) in a manner so as to maintain the time relation between positive edges of the encoder signal P(i) and corresponding vibration sample values S(i), and/or integer decimated vibration sample values S(j), through the above mentioned signal processing from detection of the analogue signals to the establishing of the speed values f_ROT .

According to an example, the status parameter extractor 450 analyses (Step S# 10) the temporal relation between three successively received position signals, in order to establish whether the monitored rotational impeller 20 is in a constant speed phase or in an acceleration phase. This analysis may be performed on the basis of information in memory 460, as described above (See Fig 8).

If the analysis reveals that there is an identical number of time slots between the position signals, status parameter extractor 450 concludes (in step #20) that the speed is constant, in which case step S#30 is performed.

In step S#30, the status parameter extractor 450 may calculate the duration between two successive position signals, by multiplication of the duration of a time slot dt= 1/fs with the number of time slots between the two successive position signals. When the position signal is provided once per full revolution of the monitored impeller 20, the speed of revolution may be calculated as

wherein ndiff = the number of time slots between the two successive position signals. During constant speed phase, all of the sample values S(j) (see column #05 in Fig 8) associated with the three analyzed position signals may be assigned the same speed value f_ROT

as defined above. Thereafter, step S# 10 may be performed again on the next three successively received position signals. Alternatively, when step S# 10 is repeated, the previously third position signal P3 will be used as the first position signal Pl (i.e. Pl := P3), so that it is ascertained whether any change of speed is at hand.

If the analysis (Step S#10) reveals that the number of time slots between the 1 :st and the 2:nd position signals differs from the number of time slots between the 2:nd and 3:rd position signals, the status parameter extractor 450 concludes, in step S#20) that the monitored rotational impeller 20 is in an acceleration phase. The acceleration may be positive, i.e. an increase in rotational speed, or the acceleration may be negative, i.e. a decrease in rotational speed also referred to as retardation.

In a next step S#40, the status parameter extractor 450 operates to establish momentary speed values during acceleration phase, and to associate each one of the measurement data values S(j) with a momentary speed value Vp which is indicative of the speed of rotation of the monitored impeller at the time of detection of the sensor signal (SEA) value corresponding to that data value S(j).

According to an example the status parameter extractor 450 operates to establish momentary speed values by linear interpolation. According to another example the status parameter extractor 450 operates to establish momentary speed values by non-linear interpolation.

Figure 10 is a flow chart illustrating an example of a method for performing step S#40 of Figure 9. According to an example, the acceleration is assumed to have a constant value for the duration between two mutually adjacent position indicators P (See column #02 in Figure 8). Hence, when

• the position indicator P is delivered once per revolution, and

• the gear ratio is 1/1 : then the angular distance travelled by the rotating impeller 20 between two mutually adjacent position indicators P is one (1) revolution, which may also be expressed as 360 degrees, and the duration is T

■ where n_diff is the number of slots of duration dt between the two mutually adjacent position indicators P.

With reference to Figure 8, a first position indicator P was detected in slot il = #03 and the next position indicator P was detected in slot i2=#45. Hence, the duration was n_diff1 = i2-il = 45-3= 42 time slots. Hence, in step S#60 (See Figure 10 in conjunction with figure 8), the status parameter extractor 450 operates to establish a first number of slots nann between the first two successive position signals Pl and P2, i.e. between position signal P(i=3) and position signal P(i=45).

In step S#70, the status parameter extractor 450 operates to calculate a first speed of revolution value VT1 . The first speed of revolution value VTlmay be calculated as

VT1= 1 /( n_diff1 *dt), wherein VT1 is the speed expressed as revolutions per second, n_diff1 = the number of time slots between the two successive position signals; and dt is the duration of a time slot, expressed in seconds.

Since the acceleration is assumed to have a constant value for the duration between two mutually adjacent position indicators P , the calculated first speed value VT1 is assigned to the time slot in the middle between the two successive position signals (step S#80).

Hence, in this example wherein first position indicator Pl was detected in slot ipi= #03 and the next position indicator P2 was detected in slot ip2 =#45; the first mid time slot is slot ipi-2 = ipi + (ip2 - ipi )/2= 3+ (45-3)/2= 3+21 )=24.

Hence, in step S#80 the first speed of revolution value VT1 may be assigned to a time slot (e.g. time slot i= 24) representing a time point which is earlier than the time point of detection of the second position signal edge P(i=45), see Figure 8.

The retro-active assigning of a speed value to a time slot representing a point in time between two successive position signals advantageously enables a significant improvement since it enables a drastic reduction of the inaccuracy of the speed value, as explained in connection with figure 13. Whereas state of the art methods of attaining a momentary rotational speed value of a centrifugal pump impeller 20 may have been satisfactory for establishing constant speed values at several mutually different speeds of rotation, the state of the art solutions appear to be unsatisfactory when used for establishing speed values for a rotational centrifugal pump impeller 20 during an acceleration phase. In this connection, it is noted that impeller speed may be affected by fluid pressure variations in the fluid system. By contrast, the methods according to examples disclosed in this document enable the establishment of speed values with an advantageously small level of inaccuracy even during an acceleration phase.

In a subsequent step S#90, the status parameter extractor 450 operates to establish a second number of slots nditrz between the next two successive position signals. In the example of Figure 8, that is the number of slots ndifc between slot 45 and slot 78, i.e. naitn = 78-45=33.

In step S#100, the status parameter extractor 450 operates to calculate a second speed of revolution value VT2. The second speed of revolution value VT2 may be calculated as

VT2= Vp61= 1 /(n_dlff2 *dt), wherein naifc = the number of time slots between the next two successive position signals P2 and P3. Hence, in the example of Figure 8, ndifiz = 33 i.e. the number of time slots between slot 45 and slot 78.

Since the acceleration may be assumed to have a constant value for the duration between two mutually adjacent position indicators P , the calculated second speed value VT2 is assigned (Step S#110) to the time slot in the middle between the two successive position signals. Hence, in the example of Figure 8, the calculated second speed value VT2 is assigned to slot 61, since 45+(78-45)/2 = 61,5. Hence the speed at slot 61 is set to

V(61) := VT2.

Hence, in this example wherein one position indicator P was detected in slot i2= #45 and the next position indicator P was detected in slot i3=#78; the second mid time slot is the integer part of: ip2-3= ip2 + (ip₃ - ip₂)/2= 45+ (78-45)/2= 45+33/2=61,5

Hence, slot 61 is the second mid time slot ip2-3-

Hence, in step S# 1 10 the second speed value VT2 may advantageously be assigned to a time slot (e.g. time slot i= 61) representing a time point which is earlier than the time point of detection of the third position signal edge P(i=78), see Figure 8. This feature enables a somewhat delayed real-time monitoring of the rotational speed while achieving an improved accuracy of the detected speed. In the next step S# 120, a first acceleration value is calculated for the relevant time period. The first acceleration value may be calculated as: all = (VT2-VTl)/((i_VT2 - ivTi)*dt)

In the example of figure 8, the second speed value VT2 was assigned to slot 61, so ivT2 = 61 and first speed value VT1 was assigned to slot 24, so ivTi = 24.

Hence, since dt=l/fs, the acceleration value may be set to all = fs* (VT2-VTl)/(ivT2 - ivri) for the time period between slot 24 and slot 60, in the example of Figure 8.

In the next step S# 130, the status parameter extractor 450 operates to associate the established first acceleration value all with the time slots for which the established acceleration value all is valid. This may be all the time slots between the slot of the first speed value VT1 and the slot of the second speed value VT2. Hence, the established first acceleration value all may be associated with each time slot of the duration between the slot of the first speed value VT1 and the slot of the second speed value VT2. In the example of Figure 8 it is slots 25 to 60. This is illustrated in column #07 of Figure 8.

In the next step S#140, the status parameter extractor 450 operates to establish speed values for measurement values s(j) associated with the duration for which the established acceleration value is valid. Hence speed values are established for each time slot which is associated with a measurement value s(j), and associated with the established first acceleration value all.

During linear acceleration, i.e. when the acceleration a is constant, the speed at any given point in time is given by the equation:

V(i) = V(i-l) + a * dt, (Eq. 3) wherein

V(i) is the momentary speed at the point of time of slot i

V(i-l) is the momentary speed at the point of time of the slot immediately preceding slot i a is the acceleration dt is the duration of a time slot According to an example, the speed for each slot from slot 25 to slot 60 may be calculated successively in this manner, as illustrated in column #08 in Figure 8. Hence, momentary speed values Vp to be associated with the detected measurement values Se(25), Se(26), Se(27)...Se(59), and Se(60) associated with the acceleration value al 2 may be established in this manner (See time slots 25 to 60 in column #08 in conjunction with column #03 and in conjunction with column #07 in Figure 8).

Hence, momentary speed values S(j) [See column #05] to be associated with the detected measurement values S(3), S(4), S(5), and S(6) associated with the acceleration value al 2 may be established in this manner.

According to another example, the momentary speed for the slot 30 relating to the first measurement value s(j)= S(3) may be calculated as:

V(i=30) = Vp30 = VT1+ a* (30-24)*dt = Vp24 + a * 6*dt

The momentary speed for the slot 40 relating to the first measurement value s(j)= S(4) may be calculated as:

V(i=40) = Vp40 = VT1+ a* (40-24)*dt = Vp40 + a* 16*dt or as:

V(i=40) = Vp40 = V(30) + (40-30)*dt = Vp30 + a* 10*dt

The momentary speed for the slot 50 relating to the first measurement value s(j)= S(5) may then subsequently be calculated as:

V(i=50) = Vp50 = V(40) + (50-40)*dt = Vp40 + a* 10*dt and the momentary speed for the slot 60 relating to the first measurement value s(j)= S(6) may then subsequently be calculated as:

V(i=60) = Vp50 + a* 10*dt

When measurement sample values S(i) [See column #03 in Figure 8] associated with the established acceleration value have been associated with a momentary speed value, as described above, an array of data including a time sequence of measurement sample values S(i), each value being associated with a speed value V(i), fROT(i), may be delivered on an output of said status parameter extractor 450 .

Alternatively, if a decimation of sample rate is desired, it is possible to do as follows: When measurement sample values S(j) [See column #05 in Figure 8] associated with the established acceleration value have been associated with a momentary speed value, as described above, an array of data including a time sequence of measurement sample values S(j), each value being associated with a speed value V(j), fRo r(j), may be delivered on an output of said status parameter extractor 450 .

With reference to figure 11, another example of a method is described. According to this example, the status parameter extractor 450 operates to record (see step S#160 in Fig 1 1) a time sequence of position signal values P(i) of said position signal (Ep) such that there is a first temporal relation naim between at least some of the recorded position signal values (P(i)), such as e.g. between a first position signal value Pl (i) and a second position signal value P2(i). According to an example, the second position signal value P2(i) is received and recorded in a time slot (i) which arrives naim slots after the reception of the first position signal value P 1 (i) (see step S# 160 in Fig 1 1). Then the third position signal value P3(i) is received and recorded (see step S# 170 in Fig 1 1) in a time slot (i) which arrives ndiff2 slots after the reception of the second position signal value P2(i).

As illustrated by step S# 180 in Fig 1 1, the status parameter extractor 450 may operate to calculate a relation value a 12= ndiffl / ndiff2

If the relation value al 2 equals unity, or substantially unity, then the status parameter extractor 450 operates to establish that the speed is constant, and it may proceed with calculation of speed according to a constant speed phase method.

If the relation value al 2 is higher than unity, the relation value is indicative of a percentual speed increase.

If the relation value al 2 is lower than unity, the relation value is indicative of a percentual speed decrease.

The relation value al 2 may be used for calculating a speed V2 at the end of the time sequence based on a speed V 1 at the start of the time sequence, e.g. as

V2 = al2 * VI

Figure 12 is a flow chart illustrating an example of a method for performing step S#40 of

Figure 9. According to an example, the acceleration is assumed to have a constant value for the duration between two mutually adjacent position indicators P (See column #02 in Figure 8). Hence, when

• the position indicator P is delivered once per revolution, and

• the gear ratio is 1/1 : then

- the angular distance travelled between two mutually adjacent position indicators P is 1 revolution, which may also be expressed as 360 degrees, and

- the duration is T = n*dt,

■ where n is the number of slots of duration dt between the first two mutually adjacent position indicators Pl and P2.

In a step

the first speed of revolution value VT1 may be calculated as VT1 = 1 /( n_d,_ffi*dt), wherein VT1 is the speed expressed as revolutions per second, ndiffl = the number of time slots between the two successive position signals; and dt is the duration of a time slot, expressed in seconds. The value of dt may e.g. be the inverse of the initial sample frequency fs.

Since the acceleration is assumed to have a constant value for the duration between two mutually adjacent position indicators P, the calculated first speed value VT1 is assigned to the first mid time slot in the middle between the two successive position signals P(i) and P(i+ndiffl).

In a step S#210, a second speed value VT2 may be calculated as VT2= 1 /(ndiff2 *dt), wherein VT2 is the speed expressed as revolutions per second, ndiff2 = the number of time slots between the two successive position signals; and dt is the duration of a time slot, expressed in seconds. The value of dt may e.g. be the inverse of the initial sample frequency fs.

Since the acceleration is assumed to have a constant value for the duration between two mutually adjacent position indicators P , the calculated second speed value VT2 is assigned to the second mid time slot in the middle between the two successive position signals P(i+ndiffl) and P(i+ndiffl+ ndiff2). Thereafter, the speed difference V_Delta may calculated as V_Delta = VT2 - VT1

This differential speed Vneita value may be divided by the number of time slots between the second mid time slot and the first mid time slot. The resulting value is indicative of a speed difference dV between adjacent slots. This, of course, assumes a constant acceleration, as mentioned above.

The momentary speed value to be associated with selected time slots may then be calculated in dependence on said first speed of revolution value VT1 , and the value indicative of the speed difference between adjacent slots.

When the measurement sample values S(i), associated with time slots between the first mid time slot and the second mid time slot, have been associated with a momentary speed value, as described above, an array of data including a time sequence of measurement sample values S(i), each value being associated with a speed value V(i) is delivered on an output of said status parameter extractor 450. The momentary speed value V(i) may also be referred to as fROT(i).

In summary, according to some examples, a first momentary speed value VT1 may be established in dependence of the angular distance delta-FI_pi-_P2 between a first positional signal Pl and a second positional signal P2, and in dependence of the corresponding duration delta-T_pi._P2 = tp2 - tpi .

Thereafter, a second momentary speed value VT2 may be established in dependence of the angular distance delta-FI_P2-_P3 between the second positional signal P2 and a third positional signal P3, and in dependence of the corresponding duration delta-T_P2-_P3= tp2 - tpi .

Thereafter, momentary speed values for the rotational impeller 20 may be established by interpolation between the first momentary speed value VT1 and the second momentary speed value VT2.

In other words, according to examples, two momentary speed values VT1 and VT2 may be established based on the angular distances delta-FI_pi-_P2, delta-FI_P2-_P3 and the corresponding durations between three consecutive position signals, and thereafter momentary speed values for the rotational impeller 20 may be established by interpolation between the first momentary speed value VT1 and the second momentary speed value VT2.

Figure 13 is a graph illustrating a series of temporally consecutive position signals Pl, P2, P3,..., each position signal P being indicative of a full revolution of the monitored impeller 20. Hence, the time value, counted in seconds, increases along the horizontal axis towards the right.

The vertical axis is indicative of speed of rotation, graded in revolutions per minute (RPM). With reference to Figure 13, effects of the method according to an example are illustrated. A first momentary speed value V(ti) = VT1 may be established in dependence of the angular distance delta-FI_pi .^between the first positional signal Pl and the second positional signal P2, and in dependence of the corresponding duration delta-Ti-2 = tp2 - tpi . The speed value attained by dividing the angular distance delta-FI_pi-_P2 by the corresponding duration (tp2 — tpi) represents the speed V(ti) of the rotational impeller 20 at the first mid time point ti, also referred to as mtp (mid time point) , as illustrated in figure 13.

Thereafter, a second momentary speed value V(t2) = VT2 may be established in dependence of the angular distance delta-FI between the second positional signal P2 and a third positional signal P3, and in dependence of the corresponding duration delta-T2-3= tp3 - tp2.

The speed value attained by dividing the angular distance delta-FI by the corresponding duration (tp3 - tp2) represents the speed V(t2) of the rotational impeller 20 at the 2:nd mid time point ti (2:nd mtp), as illustrated in figure 13.

Thereafter, momentary speed values for time values between the first mid time point and the 2:nd mid time point may be established by interpolation between the first momentary speed value VT1 and the second momentary speed value VT2, as illustrated by the curve fpoTint.

Mathematically, this may be expressed by the following equation: V(tl2) = V(tl) + a * (tl2 - tl) (Eq. 4) Hence, if the speed of the impeller 20 can be detected at two points of time (tl and t2), and the acceleration a is constant, then the momentary speed at any point of time can be calculated. In particular, the speed V(tl2) of the impeller at time 112, being a point in time after ti and before t2, can be calculated by

V(tl2) = V(ti) + a * (tl2 -ti) (Eq. 4) wherein a is the acceleration, and ti is the first mid time point ti (See Figure 13).

The establishing of a speed value as described above, as well as the compensatory decimation as described with reference to Figures 20, 21, and 22, may be attained by performing the corresponding method steps, and this may be achieved by means of a computer program 380, 394, 410 stored in memory 360, as described above. The computer program may be executed by a DSP 350. Alternatively the computer program may be executed by a Field Programmable Gate Array circuit (FPGA).

The establishing of a speed value fRor(i) as described above may be performed by the analysis apparatus 150 when a processor 350 executes the corresponding program code 380, 394, 410 as discussed in conjunction with Figure 4 above. The data processor 350 may include a central processing unit 350 for controlling the operation of the analysis apparatus 14. Alternatively, the processor 50 may include a Digital Signal Processor (DSP) 350. According to another example the processor 350 includes a Field programmable Gate Array circuit (FPGA). The operation of the Field programmable Gate Array circuit (FPGA), may be controlled by a central processing unit 350 which may include a Digital Signal Processor (DSP) 350.

Identification of data relating to the operating point of a centrifugal pump

During operation of a centrifugal pump 10 there may be an occurrence of pressure fluctuations PFP in the fluid material 30 being pumped. The pressure fluctuations in the fluid material 30 may cause mechanical vibration VFP in the pump casing 62 (Se figure 2A, 2D and/or figures 14A-G).

As mentioned above, the centrifugal pump impeller 20 has a number of vanes 310. The number L of vanes 310 is an important factor in relation to analysis of the vibrations resulting from rotation of the pump impeller 20. According to some embodiments the number L of vanes 310 may be any number higher than L=1. According to some embodiments the number L of vanes 310 may be anywhere in the range from L=2 to L=60. According to some embodiments the number L of vanes 310 may be anywhere in the range from L=2 to L=35.

The existence of a vibration signal signature SFP which is dependent on the vibration movement VFP of the casing may therefore provide information relating to a momentary internal state of the pumping process in the pump. A repetition frequency fp of the fluid pressure fluctuations signature depends on the number L of vanes 310 and on the speed of rotation f_ROT of the impeller 20.

The inventor realized that some of the mechanical vibration of the casing 62 is caused by pressure fluctuations in the fluid material 30. The repetition frequency fR of the pressure fluctuation depends on the number L of vanes 310 and on the speed of rotation FROT of the impeller 20. In fact, the inventor realized that a pressure fluctuation having a repetition frequency fp that equals the number L multiplied by the speed of rotation f_ROT of the impeller 20 constitutes a pressure fluctuation signature SFP that provides information relating to a momentary internal state of the pumping process in the pump, wherein L is the number of vanes 310 on the rotating impeller.

When the monitored centrifugal pump impeller 20 rotates at a constant rotational speed such a repetition frequency fR may be discussed either in terms of repetition per time unit or in terms of repetition per revolution of the impeller being monitored, without distinguishing between the two. However, if the centrifugal pump impeller 20 rotates at a variable rotational speed the matter is further complicated, as discussed elsewhere in this disclosure, e.g. in connection with Figures 20, 21, 22A, 22B, and 22C. In fact, it appears as though even very small variations in rotational speed of the impeller may have a large adverse effect on detected signal quality in terms of smearing of detected vibration signals. Hence, a very accurate detection of the rotational speed f_ROT of the pump impeller 20 appears to be of essence.

Moreover, the inventor realized that, not only the amplitude of the mechanical vibration VFP but also the time of occurrence of the mechanical vibration VFP may be indicative of data relating an operating point 205 of a centrifugal pump. Thus, the measurement signal SMD (See e.g. Fig 5) may include at least one vibration signal amplitude component SFP dependent on a vibration movement wherein said vibration signal amplitude component SFP has a first repetition frequency fp which depends on the speed of rotation TROT of the rotationally moving centrifugal pump impeller 20 and that also depends on the number L of vanes 310 provided on impeller 20; and wherein there is a temporal relation between the occurrence of the repetitive vibration signal amplitude component SFP and the occurrence of a position signal P(i) which has a second repetition frequency fp dependent on the speed of rotation TROT of the rotationally moving centrifugal pump impeller 20 when the second repetition frequency fp is equal to the first repetition frequency fp.

Accordingly, when there is provided a position signal Ep, P(i), P(j), P(q) indicative of a rotational position of the rotatable impeller (20) for example only once per revolution, the monitoring unit 150, 150A may be configured to generate, dependent on said position signal Ep, P(i), P(j), P(q), a reference position signal PC, P(q), P(t) having a second repetition frequency fp; the second repetition frequency fp being equal to the first repetition frequency fp. This advantageously enables the generating of the rrelation value XI, as discussed in this disclosure.

Moreover, the inventor realized that it is desirable to detect, in a time sequence of measurement sample values Se(i), S(j), S(q), a the occurrences of an event signature (Sp(r); Sp) which is repetitive with L occurrences per impeller revolution when L is higher than one so that said detected repetitive event signature Sp(r); Sp is indicative of a fluid material pressure pulsation generated when the vanes 10 interact with the fluid material 30 in the volute 75. In this connection it is noted thet the above mentioned first repetition frequency fp is equal to L occurrences per impeller revolution. As regards constant rotational speed, the inventor concluded that if the speed of rotation f_ROT is constant, the digital measurement signal SMD, comprising a temporal sequence of vibration sample values S(i), has a repetition frequency fa, that depends on the number L of vanes 310 provided.

The status parameter extractor 450 may optionally include a Fast Fourier Transformer (FFT) coupled to receive the digital measurement signal SMD, or a signal dependent on the digital measurement signal SMD (See Figure 15A and/or figure 15B). In connection with the analysis of a centrifugal pump, having a rotating impeller 20, it may be interesting to analyse signal frequencies that are higher than the rotation frequency fROT of the rotating impeller 20. In this context, the rotation frequency fROT of the impeller 20 may be referred to as ’’order 1”. If a signal of interest occurs at, say ten times per revolution of the impeller, that frequency may be referred to as Order 10, i.e. a repetition frequency fR (measured in Hz) divided by rotational speed fROT ( measured in revolutions per second, rps) equals 10 Hz/rps, i.e. order Oi = ffe/fROT = 10

Referring to a maximum order as OMAX, and the total number of frequency bins in the FFT to be used as B_n, the inventor concluded that the following applies according to an example:

Oi * B_n =NR* OMAX-

Conversely, NR = Oi * B_n / OMAX, wherein

OMAX is a maximum order; and

B_n is the number of bins in the frequency spectrum produced by the FFT, and Oi is the number L of impeller vanes 310 in the monitored centrifugal pump.

The above variables OMAX, B_n, and Oi, should be set so as to render the variable NR a positive integer. In connection with the above example it is noted that the FFT analyzer is configured to receive a reference signal, i.e. a position marker signal value PS, or Ep, once per revolution of the rotating impeller 20. As mentioned in connection with Figure 2, a position marker device 180 may be provided such that, when the impeller 20 rotates around the axis of rotation 60, the position marker 180 passes by the position sensor 170 once per revolution of the impeller, thereby causing the position sensor 170 to generate a revolution marker signal value PS, E_P.

Incidentally, referring to the above example of FFT analyzer settings, the resulting integer number NR may indicate the number of revolutions of the monitored impeller 20 during which the digital signal S D is analysed. According to an example, the above variables OMAX, B_n, and Oi, may be set by means of the Human Computer Interface, HCI, 210, 210S (See e.g. Fig 1 and/or fig. 5 and/or figure 15A and/or figure 15B).

Consider a case when the digital measurement signal SMD is delivered to an FFT analyzer: In such a case, when the FFT analyzer is set for ten vanes, i.e. L=10, and B_n = 160 frequency bins, and the user is interested in analysing frequencies up to order OMAX= 100, then the value for NR becomes NR = Oi * B_n /O A = 10* 160/100 = 16.

Hence, it is necessary to measure during sixteen impeller revolutions (NR = 16) when B_n = 160 frequency bins is desired, the number of vanes is L=10; and the user is interested in analysing frequencies up to order OMAX = 100. In connection with settings for an FFT analyzer, the order value O AX may indicate a highest frequency to be analyzed in the digital measurement signal SMD-

According to some embodiments, the setting of the FFT analyzer should fulfil the following criteria when the FFT analyzer is configured to receive a reference signal, i.e. a position marker signal value PS, once per revolution of the rotating impeller 20:

The integer value Oi is set to equal L, i.e. the number of vanes in the impeller 20, and the settable variables OMAX, and B_n are selected such that the mathematical expression

Oi * B_n /OMAX becomes a positive integer. Differently expressed: When integer value Oi is set to equal L, then settable variables OMAX and B_n should be set to integer values so as to render the variable NR a positive integer, wherein NR = Oi * B_n /OMAX

According to an example, the number of bins B_n is settable by selecting one value B_n from a group of values. The group of selectable values for the frequency resolution B_n may include B_n =200

Bn = 400

Bn = 800

B_n = 1600

Bn = 3200

Figures 14A, 14B and 14C show another example of a cross-sectional view of the pump during operation. According to the example of Figures 14 A, 14B, 14C, the centrifugal pump impeller 20 has six vanes 310, i.e. the number L=6.

For the purpose of this example, the sample frequency is such that there are n= 7680 samples per revolution at that rotational speed fROT of the impeller 20, or a multiple of that number of samples. Thus, n may be e.g. 768 samples per revolution, or n may be e.g. 76800 samples per revolution. The actual number of samples per revolution is not important, but it can vary dependent on system conditions and settings of the system.

As mentioned above, the impeller 20 is rotatable, and thus the position sensor 170 may generate a position signal Ep for indicating momentary rotational positions of the impeller 20. A position marker 180 may be provided in association with the impeller 20 such that, when the impeller 20 rotates, the position marker 180 passes by the position sensor 170 once per revolution of the impeller, thereby causing the position signal Ep to exhibit a position marker signal value Ps. Each such position marker signal value Ps is indicative of a stationary position, i.e. a certain rotational position of the impeller 20 in relation to the immobile stator. As discussed e.g. in connection with figure 2A, the pump delivers an outlet flow QOUT and a sensor 70, 70s4 may be mounted on the casing 62 by the outlet for generating a vibration signal SEA, SMD, Se(i), S(j), S(q) dependent on pressure pulsation PFP in the fluid material delivered from the pump.

It follows from Bernoulli's principle that an increase in the speed of a fluid occurs simultaneously with a decrease in fluid pressure (See equations 1 and 2 above). In an analysis of the flow pattern out of the pump 10 it is therefore of interest to look at the momentary pressure P54 in the outlet region and its dependence on the fluid speed V54 (See e.g. Figure 14A part I). The continuity equation for a fluid means that the total flow into and out of a closed volume must be zero. In other words, the sum of the flow into a closed volume and the flow out of the closed volume must be zero. For an incompressible fluid in a flow pipe, such as the outlet of the pump 10, the continuity equation can thus be written:

V1 Al = V2 A2 wherein

Ai = the inflow area

Vi = the fluid speed through inflow area Ai

A2 = the outflow area V2 = the fluid speed through outflow area A2

When the cross-sectional area of the outlet is constant it follows that a pulsating flow QOUT must result in a pulsating fluid speed V54. A pulsating fluid speed V54 occurs simultaneously with a pulsating fluid pressure P54, in accordance with Bernoulli's principle.

Figure 14A illustrates an interpretation of a flow pattern during BEP Operation, i.e. flow at design point.

Figure 14A part I illustrates a rotational position of the rotating impeller 20 wherein a vane tip 310A is just passing by the tongue 65. Here, vane tip 310A is at its closest position to the tongue, and the passage opening between narrow volute portion 77 and the broad volute portion 78 is at its minimum. The vane 310A is followed by an adjacent vane 31 OB.

When the pump operates at a state such that the total output flow QOUT from the outlet 66 is the flow for which the pump was designed, i.e. the Best Efficiency Point flow Q_OUTBEP of the pump, then the pressure pulsation in the fluid exhibits minimal pulsation amplitudes (see 550BEP in Figure 19A in conjunction with figure 14A).

As illustrated in figure 14A, the position marker 180 may be located, in relation to the impellers, such that the position signal Ep exhibits a position marker signal value PS when vane tip 310A is at its closest position to the tongue 65. When that is the case, then the exhibited minimal pulsation amplitudes appear to occur at a zero degree phase angle.

The momentary flow from the outlet 66 at the moment shown in Figure MAI is here referred to as Q_OUTBEPI.

Figure 14A part II illustrates another rotational position of the rotating impeller 20, a short time later than the rotational position shown in Figure 14A part I. In figure 14A, part II the adjacent vane 310B is located closer to the tongue 65, and the vane 310A now is located in the narrow volute section 77, whereas vane 310B is located in the larger volute section 78. Thus, at this moment the impeller passage 320, between vane 310A and vane 310B, provides a larger passage opening between narrow and broad volute portions 77 and 78. A portion of the flow from inlet 64, through the passage 320 between vanes 310A and 310B, goes to the larger volute portion, and another portion of the flow from inlet 64, through the passage 320 between vanes 310A and 310B, goes to the narrow volute portion at the moment when the impeller 20 is in the rotational position shown in Figure 14A part II during BEP Operation. It is believed that there is no “leak flow” between narrow and broad volute portions during BEP Operation, or that there is substantially no “leak flow” between narrow and broad volute portions during BEP Operation. Thus, at the moment illustrated in Fig 14A part II when the passage 320 between vanes 310 A and 31 OB opens equally much to the narrow volute section and to the larger volute section, then approximately half of the flow from inlet 64, through the passage between vanes 310A and B, goes to the larger volute portion, and approximately half of the flow from inlet 64, through the passage between vanes 310A and B, goes to the narrow volute portion during BEP Operation.

The momentary flow from the outlet 66 at the moment shown in Figure 14 All is here referred to as Q_OUTBEP H. It appears as if the momentary flow Q_OUTBEP H is of substantially the same magnitude as the momentary flow Q_OUTBEP I (Figure MAI). However, it is believed that the momentary flow Q_OUTBEP H may deviate by a very small amount from the momentary flow Q_OUTBEP I, thereby rendering a relatively small pulsation during BEP operation.

Figure 14A part III illustrates a rotational position of the impeller 20 wherein the vane tip 310B is just passing by the tongue 65. Here, vane tip 310B is at its closest position to the tongue 65, so that the vane tip 310B substantially closes the passage opening between narrow and broad volute portions. The vane 310B is followed by an adjacent vane 310C. Thus, Figure 14A part III corresponds to Figure 14A part I. Accordingly, the momentary flow from the outlet 66 at the moment shown in Figure 14AIII, here referred to as Q_OUTBEP IH, is of the same magnitude as the momentary flow Q_OUTBEP I (Figure MAI).

Figure 14B illustrates an interpretation of a flow pattern during operation at a total output flow QOUT below design point, i.e. below BEP. The low momentary flow from the outlet 66 at the moment shown in Figure 14B part I is here referred to as QOUTLOI-

As indicated in Fig 14B part II, there appears to be a leakage flow q3’ from the large volute portion 78 to the narrow volute portion 77. Therefore, the momentary flow from the outlet 66 at the moment shown in Figure 14B part II, here referred to as QOUTLOII, appears to be lower than the momentary flow QOUTLOI.

The momentary outlet flow QOUTLOII is believed to be of a magnitude QOUTLOI - q3’. The leakage flow q3’ from the large volute portion 78 to the narrow volute portion 77 during operation at a flow below design point is believed to be caused by a pressure difference between the large volute portion 78 and the narrow volute portion 77. This is because a pressure P?s in the large volute portion 78 is higher than a pressure P77 in the narrow volute portion 77 during operation at a flow below design point.

From a perspective of flow through the pump, from pump inlet to pump outlet, the moment shown in Figure 14B part III corresponds to the moment shown in Figure 14B part I. Accordingly, the momentary flow from the outlet 66 at the moment shown in Figure 14BIII, here referred to as QOUTLOIII, is believed to be of the same magnitude as the momentary flow QOUTLOI (Figure 14BI).

The flow cycle illustrated by figure 14B part I, 14B part II, 14B part III therefore appears to exhibit a pulsation, the amplitude of that pulsation being dependent on the magnitude of the maximum leakage flow q3’. When the impeller has L = 6 vanes, then the pulsation will exhibit L=6 such flow cycles as the impeller rotates a full revolution.

It is believed that the above described flow pulsation renders a pulsating fluid speed V54 in the region 54 (See figure 1 and 2 A in conjunction with figure 14B). Accordingly, in view of Bernoulli's principle, the fluid pressure P54 in that region 54 also exhibits a pulsation. Thus, the fluid pressure pulsation PFP in that region 54 has a repetition frequency fR dependent on a speed of rotation FROT of the impeller 20.

More particularly, the pressure P54, detected by vibration sensor 70, 7054 positioned to detect pressure fluctuations in the outlet fluid from the pump 10 would appear to exhibit cycles as follows:

When the impeller moves from the position shown in figure 14B part I to the position shown in figure 14B part II, there is a reduction in the flow, from QOUTLOI to QOUTLOI - q3’, and therefore a reduction in the speed V54 rendering an increase in the pressure P54.

Conversely, when the impeller moves from the position shown in figure 14B part II to the position shown in figure 14B part III, there is an increase in the flow, from QOUTLOI - q3’ to QOUTLOI, and therefore an increase in the fluid speed V54 rendering a reduction in the pressure P54. Accordingly, the phase of the detected pressure pulsation P54 depends on the current Operating Point 205 in relation to BEP and on impeller position (See Figure 2B). The below table summarizes an interpretation of how the momentary outlet fluid pressure P54 changes in dependence on impeller position when the pump operates at an outlet flow below BEP flow.

It appears as though the amplitude and the phase value of the detected pressure pulsation P54 is indicative of the current Operating Point 205 in relation to BEP.

Accordingly, it appears to be of interest to establish the impeller position at the moment of occurrence of the highest peak value P54. Another way of expressing this is: In terms of the distance between two adjacent vane tips, 310A and 10B, it appears to be of interest to establish at what position, between the two adjacent vane tips, the highest peak value P54 occurs. In this connection reference is also made to the discussion about the phase value of the detected pressure pulsation in connection with table 5 below.

Figure 14C illustrates an interpretation of a flow pattern during operation at a total output flow QOUT above design point, i.e. above BEP.

The relatively high momentary flow from the outlet 66 at the moment shown in Figure 14C part I is here referred to as QOUTHSI.

As indicated in Fig 14C part II, there appears to be a leakage flow q3 from the narrow volute portion 77 to the large volute portion 78. Therefore, the momentary flow from the outlet 66 at the moment shown in Figure 14C part II, here referred to as QOUTHHI, appears to be higher than the momentary flow QOUTHH.

The momentary outlet flow QOUTHIII is believed to be of a magnitude QOUTHH + q3. The leakage flow q3 from the narrow volute portion 77 to the large volute portion 78 during operation at a flow level higher than design point is believed to be caused by a pressure difference between the narrow volute portion 77 and the large volute portion 78. This is because a pressure P?s in the large volute portion 78 is lower than a pressure P77 in the narrow volute portion 77 during operation at a flow above design point.

From a perspective of flow through the pump, from pump inlet to pump outlet, the moment shown in Figure 14C part III corresponds to the moment shown in Figure 14C part I. Accordingly, the momentary flow from the outlet 66 at the moment shown in Figure 14C part III, here referred to as QOUTHUII, is believed to be of the same magnitude as the momentary flow OUTHU (Figure 14C part I).

The flow cycle illustrated by figure 14C part I, 14C part II, 14C part III therefore appears to exhibit a pulsation, the amplitude of that pulsation being dependent on the magnitude of the maximum leakage flow q3. When the impeller has L = 6 vanes, then the pulsation will exhibit L=6 such flow cycles as the impeller rotates a full revolution. As discussed above in connection with figure 14B, and in view of Bernoulli's principle, the fluid pressure P54 in the region 54 near the pump the outlet 66 exhibits a fluid pressure pulsation PFP.

More particularly, the pressure P54, detected by vibration sensor 70, 7O54 positioned to detect pressure fluctuations in the outlet fluid from the pump 10 would appear to exhibit cycles as follows:

When the impeller moves from the position shown in figure 14C part I to the position shown in figure 14C part II, there is an increase in the flow, from QOUTHU to QOUTHH + q3, and therefore an increase in the fluid speed V54 rendering a reduction in the pressure P54.

Conversely, when the impeller moves from the position shown in figure 14C part II to the position shown in figure 14C part III, there is a reduction in the flow, from QOUTHU + q3 to QOUTHH, and therefore a reduction in the fluid speed V54 rendering an increase in the pressure P54.

Accordingly, the phase of the detected pressure pulsation P54 depends on the current Operating Point 205 in relation to BEP and on impeller position (See Figure 2B). The below table summarizes an interpretation of how the momentary outlet fluid pressure P54 changes in dependence on impeller position when the pump operates at an outlet flow higher than BEP flow.

Accordingly, it appears to be of interest to establish the impeller position at the moment of occurrence of the lowest peak value P54. Another way of expressing this is: In terms of the distance between two adjacent vane tips, 310A and 31 OB, it appears to be of interest to establish at what position, between the two adjacent vane tips, the lowest peak value P54 occurs. In this connection reference is also made to the discussion about the phase value of the detected pressure pulsation in connection with table 5 below.

According to an interpretation, the flow patterns illustrated by figures 14A to 14C provide a cause of the detected phase values as discussed e.g. in relation to figures 16 to 19D.

In particular, it is noted that said first polar angle (Xl (r), FI(r), 0(r), TD, TDI) exhibits a phase shift of approximately 180 degrees, when the operating point 205 changes from below BEP to above BEP, and/or when the operating point 205 changes from above BEP to below BEP. Thus, this phase shift is to be kept in mind when looking at figures 14B and 14C. In this connection, reference is made to internal status indicator object 550 which is discussed elsewhere in this disclosure, e.g. in connection with figures 16 to 19D.

Accordingly, it appears to be desirable to control the pump such that a current internal status 550(r) is shifted towards the reference point (O, 530) at origin, in the polar plot according figures 16 to 19B, or to a position which is as close as possible the reference point (O, 530), so that the flow pattern is as close as possible to the flow pattern indicated in figures 14A. Figures 14D, 14E and 14F show another example of a cross-sectional view of the pump during operation, and they illustrate another aspect of flow and pressure patterns in the pump, and the detection thereof. According to the example of Figures 14D, 14E and 14F the centrifugal pump 10 may include a sensor 70, 70?? attached to the casing 62 at the first volute part 77 by the narrower cross sectional area near the tongue 65 (See also figure 2D).

The pump 10 of Figures 14D, 14E and 14F may include parts, and be configured, as described above in relation to figures 1 A, 2A and 2D and/or as described elsewhere in this document. However, the example centrifugal pump 10 of Figures 14D, 14E and 14F may include a sensor 70, 70?7 attached to the casing 62 at the first volute part 77 by the narrower cross sectional area near the tongue 65.

The positioning of the sensor 70?7, as illustrated in figures 14D, 14E and 14F, appears to be advantageous in that the sensor is located comparatively close to the passing vane tips, which appear to exhibit detectable local high pressures and low pressures when the pump runs away from BEP flow, as discussed in more detail below in connection with figures 14E and 14 F.

Figure 14D parts I, II and III illustrate an interpretation of a flow and pressure pattern during BEP Operation, i.e. flow at design point.

As mentioned above the fluid may flow axially towards the inlet 64 at the centre of the impeller 20, and the rotating impeller vanes 310 deflect the fluid so that it flows out through apertures 320 between the vanes 310. The rotating impeller vanes 310 cause centrifugal acceleration of the fluid, and thus, the fluid undergoes a change in direction and is accelerated. When the pump is running at BEP flow Q_OUTBEP the accelerated fluid, when reaching the tip of the vanes and departing from the apertures 320 into the volute 75 has reached a tangential velocity V75, and when the pump is running at BEP flow Q_OUTBEP the tangential fluid velocity V75 is maintained as the fluid travels along the volute 75 to the outlet 66.

Thus, the accelerated fluid 30 has a tangential speed component v75 that corresponds to the tangential speed of the vane tips 310A, 310B, 310C, when the pump is running at BEP flow Q_OUTBEP. In fact, if the pump is running exactly at BEP flow Q_OUTBEP, then the tangential fluid speed component V75 appears to be the same as the tangential speed VJIOT of the vane tips. In this manner, as the fluid travels along the volute 75, it is joined by more and more fluid 30 exiting the rotating impeller passages 320 but, as the cross sectional area of the volute increases, the tangential fluid velocity V75 is maintained when the pump is running at BEP flow Q_OUTBEP.

Incidentally, the accelerated fluid 30 also has a radial speed component V?SR that corresponds to the gradual widening of the cross-sectional area of the volute, when the pump is running at BEP flow Q_OUTBEP. The gradual widening of the cross-sectional area of the volute is such that the amount of fluid per time unit being added to the volute is balanced by the widening per time unit of the cross-sectional area when the pump is running at BEP flow Q_OUTBEP. Thus, in accordance with the continuity equation, the tangential fluid velocity V75 is maintained when the pump is running at BEP flow Q_OUTBEP.

In this manner, the fluid appears to exhibit laminar flow, or substantially laminar flow, in the volute when the pump is running at BEP flow Q_OUTBEP

Figure 14D part I illustrates a rotational position of the rotating impeller 20 wherein a vane tip 310A is just passing by the tongue 65. Here, vane tip 310A is at its closest position to the tongue, and the passage opening between narrow volute portion 77 and the broad volute portion 78 is at its minimum. The vane 310A is followed by an adjacent vane 310B.

The momentary flow from the outlet 66 at the moment shown in Figure 14DI is here referred to as Q_OUTBEPI.

Figure 14D part II illustrates another rotational position of the rotating impeller 20, a short time later than the rotational position shown in Figure 14D part I. In figure 14D, part II the adjacent vane 310B is located closer to the tongue 65, and the vane tip 310A now is located in the narrow volute section 77, whereas vane 310B is located in the larger volute section 78. Thus, at this moment the vane tip 310A now is located comparatively close to the vibration sensor 7O77, as illustrated in figure 14D part II. This appears to be advantageous, as discussed in more detail below in relation to figures 14E and 14F.

The accelerated fluid 30, at the vane tip 310A, has a tangential fluid speed component V77 that corresponds to the tangential speed V310T of the vane tip 310A, when the pump is running at BEP flow Q_OUTBEP. AS the fluid 30 travels along the volute 75, it is joined by more and more fluid 30 exiting the rotating impeller passages 320 but, as the cross sectional area of the volute increases, the tangential fluid velocity V75 is maintained when the pump is running at BEP flow Q_OUTBEP, and the tangential fluid speed component v?8 in the wide part 78 of the volute is same, or approximately the same, as the tangential fluid speed component V77 in the narrow part 77 of the volute.

Figure 14D part III illustrates a rotational position of the impeller 20 wherein the vane tip 310B is just passing by the tongue 65. Here, vane tip 310B is at its closest position to the tongue 65, so that the vane tip 31 OB substantially closes the passage opening between narrow and broad volute portions. The vane 31 OB is followed by an adjacent vane 310C. Thus, Figure 14D part III corresponds to Figure 14D part I. Accordingly, the momentary flow and pressure pattern at the moment shown in Figure 14DIII is the same as the flow and pressure pattern at the moment shown in Figure 14DI.

Vane tip local pressure regions during operation at flow lower than BEP flow

Figure 14E parts I, II and III illustrate an interpretation of a flow and pressure pattern during operation at a total output flow QOUTLO below design point, i.e. below BEP flow. The low momentary flow from the outlet 66 at the moment shown in Figure 14E part I is here referred to as QOUTLOI.

As mentioned above the fluid may flow axially towards the inlet 64 at the centre of the impeller 20, and the rotating impeller 20 deflects the fluid so that it flows out through apertures 320 between the vanes 310 (See fig. 2D in conjunction with figure 14D, 14E, 14F). The rotating impeller causes centrifugal acceleration of the fluid, and thus, the fluid undergoes a change in direction and is accelerated. When the pump is running at an output flow QOUTLO below design point, i.e. below BEP flow, the accelerated fluid, when reaching the tip of the vanes and departing from the apertures 320 into the volute 75 has reached a radial speed component V75R that is low in relation to the gradual widening of the cross-sectional area of the volute. The amount of fluid entering the volute 75 from an aperture 320 between two adjacent vanes 310, as a consequence of the low radial speed component V75R, is such that the amount of fluid per time unit being added to the volute is smaller than the widening per time unit of the cross-sectional area when the pump is running at an output flow QOUTHI above design point. Thus, in accordance with the continuity equation, the tangential fluid velocity V75 is gradually decreased when the pump is running at an output flow QOUTHI below design point. Thus, with reference to figure 14E part II, the tangential fluid velocity V78 in the wide part 78 of the volute is lower than the tangential fluid velocity V77 in the narrower part 77 when the pump is running at an output flow below design point.

Accordingly, an effect of the pump running below design point is that the tangential fluid velocity V75 becomes lower than the tangential velocity V75T of the vane tips. Now, when we look at an individual vane tip, this speed deviation, between the higher tangential velocity V75T of the vane tip at the inner edge of the volute and the lower tangential fluid velocity V75, causes a local high pressure region on the leading side of the vane tip, indicated by a plus sign “+” in figure 14F parts I, II and III, and a local low pressure region on the trailing side of the vane tip, indicated by a minus sign

in figure 14F parts I, II and III.

Figure 14E part I illustrates a rotational position of the rotating impeller 20 wherein a vane tip 310A is just passing by the tongue 65. Thus, at this moment, the local high pressure region on the leading side of the vane tip 310A, indicated by a plus sign “+” in figure 14E part I, is approaching the sensor 7O77 and it is believed to cause an increase of the momentary fluid pressure in the region of fluid adjacent the sensor 7O77.

Figure 14E part II illustrates another rotational position of the rotating impeller 20, a short time later than the rotational position shown in Figure 14E part I. In figure 14E, part II, the vane tip 310A is located in the narrow volute section 77 and it is just passing by the sensor 7O77. Thus, at this moment the vane tip 310A now is located comparatively close to the vibration sensor 7O77, as illustrated in figure 14E part II, and the momentary fluid pressure in the region of fluid adjacent the sensor 7O77 is believed to decrease from the high pressure of the leading side of the vane tip 310A towards the low pressure of the trailing side of vane tip 310A indicated by a minus sign

in figure 14E part II. Accordingly, at the moment illustrated by Figure 14E part II, the sensor 70?7 appears to detect a negative pressure derivative.

Figure 14E part III illustrates a rotational position of the impeller 20 a short time later than the rotational position shown in Figure 14E part II, and the vane tip 310B is just passing by the tongue 65. Accordingly, at the moment illustrated in Figure 14E part III, the sensor 7O77 is believed to detect a positive pressure derivative since the local low pressure of the trailing side of vane tip 310A is departing from the region of fluid adjacent the sensor 7O77 and the local high pressure of the leading side of vane tip 31 OB is approaching the region of fluid adjacent the sensor 7O77.

Accordingly, the phase of the detected pressure pulsation P77 depends on the current Operating Point 205 in relation to BEP and on impeller position (See Figure 2B). The below table summarizes an interpretation of how the momentary fluid pressure P77 changes in dependence on impeller position when the pump operates at an outlet flow below BEP flow.

Thus, it appears as though the amplitude and the phase value of the detected pressure pulsation P77 is indicative of the current Operating Point 205 in relation to BEP. In this connection reference is also made to the discussion about the phase value of the detected pressure pulsation in connection with table 5 below.

As a consequence of the higher tangential velocity of the vane tip and the lower tangential fluid velocity V75, causing local high pressure regions on the leading sides of the vane tips, indicated by plus signs “+” in figure 14E parts I, II and III, and causing local low pressure regions on the trailing sides of the vane tips, indicated by minus signs in figure 14E parts I, II and III, the fluid appears to exhibit turbulent flow in the volute when the pump is running at an output flow QOUTLO below design point, i.e. lower than BEP flow. The occurrence of turbulent flow therefore appears to result in a lower energy efficiency of the pumping process, since a part of the energy fed to the impeller by a drive motor results in whirling fluid movement and increased warming of the fluid as a result of the whirls.

In this manner, the fluid appears to exhibit turbulent flow in the volute when the pump is running at an output flow QOUTLO below design point, i.e. lower than BEP flow. From a perspective of flow through the pump, from pump inlet to pump outlet, the moment shown in Figure 14E part III corresponds to the moments shown in Figure 14E part I, and Figure 14B part I and Figure 14B part III. Accordingly, the momentary flow from the outlet 66 at the moment shown in Figure 14E part III, here referred to as QOUTLOIII, is believed to be of the same magnitude as the momentary flow QOUTLOI (See Figure 14E part I and Figure 14B part I). By contrast, the momentary flow from the outlet 66 at the moment shown in Figure 14E part II, here referred to as QOUTLOII, is believed to be lower than the momentary flows QOUTLOI and QOUTLOIII (Figures 14E part I & 14E part III). The momentary flow QOUTLOII (Figure 14E part II) corresponds to the flow QOUTLOII in figure 14B part II. When the pump is running at an output flow below design point, the outlet flow QOUTLO therefore appears to exhibit a pulsation, the amplitude of that pulsation being dependent on the magnitude of the maximum leakage flow q3’, as discussed above in connection with figures 14B part I, part II and part III. Moreover, experiments appear to indicate that the amplitude of vibrations detected by sensor 70, 70?7 attached to the casing 62 at the first, narrower, volute part 77 increase in magnitude when the pump operates further away from the design point. Moreover, experiments appear to indicate that the amplitude of vibrations detected by sensor 70, 70?7 attached to the casing 62 at the first, narrower, volute part 77 corresponds to the magnitude of the pulsation in the outlet flow QOUTLO when the pump is running at an output flow QOUTLO below design point, i.e. lower than BEP flow. When the impeller has L = 6 vanes, then the pulsation will exhibit L=6 such flow cycles as the impeller rotates a full revolution.

Vane tip local pressure regions during operation at flow higher than BEP flow Figure 14F parts I, II and III illustrate an interpretation of a flow and pressure pattern during operation at a total output flow QOUTHI above design point, i.e. higher than BEP flow. The high momentary flow from the outlet 66 at the moment shown in Figure 14F part I is here referred tO aS QoUTHil.

As mentioned above the fluid may flow axially towards the inlet 64 at the center of the impeller 20, and the rotating impeller 20 deflects the fluid so that it flows out through apertures 320 between the vanes 310. The impeller vanes 310 cause centrifugal acceleration of the fluid, and thus, the fluid undergoes a change in direction and is accelerated. When the pump is running at an output flow QOUTHI above design point, i.e. higher than BEP flow, the accelerated fluid, when reaching the tip of the vanes and departing from the apertures 320 into the volute 75 has reached a radial speed component V75R that is high in relation to the gradual widening of the cross-sectional area of the volute. The amount of fluid entering the volute 75 from an aperture 320 between two adjacent vanes 310, as a consequence of the high radial speed component V75R, is such that the amount of fluid per time unit being added to the volute exceeds the widening per time unit of the cross-sectional area when the pump is running at an output flow QouTHi above design point. Thus, in accordance with the continuity equation, the tangential fluid velocity V75 is gradually increased when the pump is running at an output flow QouTHi above design point. With reference to figure 14F part II, tangential fluid velocity v?s in the wide part 78 of the volute is higher than the tangential fluid velocity V77 in the narrower part 77 when the pump is running at an output flow above design point.

Accordingly, an effect of the pump running above design point is that the tangential fluid velocity V75 becomes higher than the tangential velocity of the vane tips. Now, when we look at an individual vane tip, this speed deviation, between the higher tangential fluid velocity V75 and the lower tangential velocity of the vane tip, causes a local high pressure region on the trailing side of the vane tip, indicated by a plus sign “+” in figure 14F parts I, II and III, and a local low pressure region on the leading side of the vane tip, indicated by a minus sign in figure 14F parts I, II and III.

Figure 14F part I illustrates a rotational position of the rotating impeller 20 wherein a vane tip 310A is just passing by the tongue 65. Thus, at this moment, the local low pressure region on the leading side of the vane tip 310A, indicated by a minus sign in figure 14F part I, is approaching the sensor 7O77 and it is believed to cause a lowering of the pressure in the region of fluid adjacent the sensor 7O77.

Figure 14F part II illustrates another rotational position of the rotating impeller 20, a short time later than the rotational position shown in Figure 14F part I. In figure 14F, part II, the vane tip 310A is located in the narrow volute section 77 and it is just passing by the sensor 7O77. Thus, at this moment the vane tip 310A now is located comparatively close to the vibration sensor 7O77, as illustrated in figure 14F part II, and the momentary fluid pressure in the region of fluid adjacent the sensor 7O77 is believed to increase from the low pressure of the leading side of the vane tip 310A towards the high pressure of the trailing side of vane tip 310A indicated by a plus sign “+ “ in figure 14F part II. Accordingly, at the moment illustrated by Figure 14F part II, the sensor 70?7 appears to detect a positive pressure derivative.

Figure 14F part III illustrates a rotational position of the impeller 20 a short time later than the rotational position shown in Figure 14F part II, and the vane tip 310B is just passing by the tongue 65. Accordingly, at the moment illustrated in Figure 14F part III, the sensor 70?7 is believed to detect a negative pressure derivative since the local high pressure of the trailing side of vane tip 310A is departing from the region of fluid adjacent the sensor 70?7 and the local low pressure of the leading side of vane tip 31 OB is approaching the region of fluid adjacent the sensor 70??.

Accordingly, the phase of the detected pressure pulsation P77 depends on the current Operating Point 205 in relation to BEP and on impeller position (See Figure 2B). The below table summarizes an interpretation of how the momentary fluid pressure P77 changes in dependence on impeller position when the pump operates at an outlet flow higher than BEP flow.

As a consequence of the higher tangential fluid velocity V75 and the lower tangential velocity of the vane tip, causing local high pressure regions on the trailing sides of the vane tips, indicated by plus signs “+” in figure 14F parts I, II and III, and causing local low pressure regions on the leading sides of the vane tips, indicated by minus signs

in figure 14F parts I, II and III, the fluid appears to exhibit turbulent flow in the volute when the pump is running at an output flow QOUTHI above design point, i.e. higher than BEP flow. The occurrence of turbulent flow therefore appears to result in a lower energy efficiency of the pumping process, since a part of the energy fed to the impeller by a drive motor results in whirling fluid movement and increased warming of the fluid as a result of the whirls.

In this manner, the fluid appears to exhibit turbulent flow in the volute when the pump is running at an output flow QOUTHI above design point, i.e. higher than BEP flow.

From a perspective of flow through the pump, from pump inlet to pump outlet, the moment shown in Figure 14F part III corresponds to the moments shown in Figure 14F part I, and Figure 14C part I and Figure 14C part III. Accordingly, the momentary flow from the outlet 66 at the moment shown in Figure 14F part III, here referred to as QOUTHHII, is believed to be of the same magnitude as the momentary flow QOUTHU (Figure 14F part I and Figure 14C part I). By contrast, the momentary flow from the outlet 66 at the moment shown in Figure 14FII, here referred to as QOUTHHI, is believed to be higher than the momentary flows QOUTHU and QOUTHHII (Figures 14F part I & 14F part III). The momentary flow QOUTHHI (Figure 14F part II) corresponds to the flow QO THHI in figure 14C part II. When the pump is running at an output flow above design point, the outlet flow QOUTHI therefore appears to exhibit a pulsation, the amplitude of that pulsation being dependent on the magnitude of the maximum leakage flow q3, as discussed above in connection with figures 14C part I, part II and part III.

Moreover, experiments appear to indicate that the amplitude of vibrations detected by sensor 70, 70?7 attached to the casing 62 at the first, narrower, volute part 77 increase in magnitude when the pump operates further away from the design point. Moreover, experiments appear to indicate that the amplitude of vibrations detected by sensor 70, 7O77 attached to the casing 62 at the first, narrower, volute part 77 corresponds to the magnitude of the pulsation in the outlet flow QouTHi when the pump is running at an output flow QOUTHI above design point, i.e. higher than BEP flow. When the impeller has L = 6 vanes, then the pulsation will exhibit L=6 such flow cycles as the impeller rotates a full revolution.

According to an interpretation, the flow and pressure patterns illustrated by figures 14D to 14F provide a cause of the detected phase values as discussed e.g. in relation to figures 16 to 19D. In particular, it is noted that said first polar angle XI (r), FI(r), <P(r), TD, TDI exhibits a phase shift of approximately 180 degrees, when the operating point 550 changes from below BEP to above BEP, or vice versa. Thus, this phase shift is to be kept in mind when looking at figures 14E and 14F. In this connection, reference is made to internal status indicator object 550 which is discussed elsewhere in this disclosure, e.g. in connection with figures 16 to 19D.

Moreover, an analysis appears to indicate that a detected pressure signal 70?7 exhibits a different phase as compared to detected pressure signal 7O54. Thus it may be possible to evaluate or detect an internal state of said centrifugal pump 10 based on said mutual order of occurrence of the vibration signature detected by sensor 7054 and the vibration signature detected by sensor 7O77.

A method of identifying the current operating point

Figure 14G is another illustration of the example pump 10 of any of figures 1 A, IB, 2A, 2B, 2D, 2E or any of 14A to 14F. The disclosure relating to Figure 14G may be relevant to any of the pumps discussed in this disclosure. For the sake of clarity, the example pump illustrated in figure 14G does not illustrate all features of the pump 10. For example, figure 14G shows one of the walls of the pump outlet, but the wall part close to the tongue 65 has been eliminated from figure 14G so as to more clearly show an example stator position Pl, Ps.

As shown in figure 14G the example pump 10 comprises a casing 62 in which a rotatable impeller 20 is disposed so that it can rotate around an axis of rotation 60. The casing 62 forms a volute 75 and the pump includes a tongue 65 separating one part 77 of the volute from another part 78 of the volute. The tongue 65 has a tongue tip 65T. The tongue 65 may have an elongated shape wherein the tip 65T may form an edge. Thus, the tongue 65 may separate the outlet pipe 66 from the narrow volute part 77.

In other words, the casing 62 may include a tongue 65 having an elongated shape wherein the elongated tip 65T may form an edge that separates an outlet 66 from a narrow volute part 77. During operation of the pump, at the Best Efficiency Operating Point (BEP), fluid that approaches the tongue tip 65T will ideally be divided in two parts so as to flow in the directions from the elongated tongue tip 65T to the outlet 66, and from the elongated tongue tip 65T into the narrow volute part 77 (See figure 14G in conjunction with figure 14A and/or figure 14D). The example pump illustrated in figure 14G is designed for clockwise direction of the impeller rotation. As shown in Figure 14G, a position marker device 180 may be provided in association with the impeller 20 such that, when the impeller 20 rotates around the axis of rotation 60, the position marker 180 passes by the position sensor 170 once per revolution of the impeller, thereby causing the position sensor 170 to generate a revolution marker signal value PS. Alternatively, position signal values PS, PC may be generated by an encoder 170, as disclosed elsewhere in this disclosure.

When there is one position marker signal value Ps per revolution and the rotational speed FROT is constant, or substantially constant, there will be a constant, or substantially constant, number of vibration sample values S(i) for every revolution of the pump impeller 20. For the purpose of this example, the position signal P(0) is indicative of the vibration sample i=0, as shown in table 2 (See below). For the purpose of an example, the position of the position signal P(0) in relation to the impeller 20 may not be important, as long as the repetition frequency fp is dependent on the speed of rotation FROT OF the rotationally moving centriFugal pump impeller 20. Hence, iF the position signal Ep has one pulse Ps per revolution oF the impeller 20, the digital position signal will also have one Position signal value P(i) = 1 per revolution, the remaining Position signal values being zero.

Table 2

Thus, at a certain constant speed FROT there may be n time slots per revolution, as indicated by table 2, and n may be a positive integer. In the example of table 2, n = 7680.

Having one position signal Ps per revolution, we know that the position signal Ps=l will be repetitive every n slots when the rotational speed f_ROT is constant. Thus, a number of virtual position signals Pc may be generated by calculation. In an example, consider that virtual position signals Pc are generated. The provision of L virtual position signals Pc, i.e. one virtual position signal Pc per vane 310, may be used for establishing a temporal relation between the occurrence of the repetitive vibration signal amplitude component SFP which has a first repetition frequency R and the occurrence of a position signal Pc, P(i) which has a second repetition frequency fp dependent on the speed of rotation FROT of the rotationally moving centrifugal pump impeller 20; wherein the second repetition frequency fp equals the first repetition frequency FR

Having L equidistant vanes 310 in the impeller and one position signal Ps per revolution it is possible to generate one virtual position signal Pc per vane, so that the total number of position signals Ps, Pc are evenly distributed. Each such position marker signal value Ps and Pc is indicative of a stationary position, i.e. a position of the immobile casing 62, as illustrated by “Ps” and “Pc” in figures 14G. The casing 62 may also be referred to as stator 62, since it is static or immobile. Thus, a position signal Ps or Pc will occur at every n/L sample value position, as indicated in Table 3, when there are provided n time slots per revolution. In table 3, n=7680, and L=6, and thus there is provided a position signal Pc at every 1280 sample, the calculated position signals being indicated as 1C.

As illustrated in the Figure 14G example, the position marker signal values Ps and Pc are indicative of L stationary positions Pl, P2, P3, P4, P5 and PL, where L =6, since there are 6 vanes 310, 310i, 3102, 3103, 3104, 3105, 310e, 310L in the illustrated impeller 20.

It may be assumed that the operating point of the pump is substantially constant during a single revolution of the impeller 20. In other words, the position of the pulsation event in the fluid is substantially immobile during a single revolution of the impeller 20.

Since the vibration signal amplitude component SFP, Sp is generated by a pulsation event in the fluid (See figures 14A to 14F), it will be repetitive with the frequency of one vibration signal amplitude component SFP, Sp per vane 310. Thus, it can be assumed that the temporal relation between the occurrence of the repetitive vibration signal amplitude component SFP, Sp and the occurrence of a position signal P, PC will be substantially constant for each of the L data blocks, L being L=6 in this example.

Table 3 illustrates the principle of a temporal progression of position signal values P(i) with calculated Positions signal values P(i) being indicated as “1C”.

Table 3

Table 4

Table 5

As mentioned above, the impeller 20 is rotatable around the axis of rotation 60, and thus the position sensor 170, being mounted in an immobile manner, may generate a position signal Ep having a sequence of impeller position signal values Ps for indicating momentary rotational positions of the impeller 20. As shown in Figure 2A a position marker 180 may be mechanically coupled to the impeller 20 such that, when the impeller 20 rotates around the axis of rotation 60, the position marker 180 passes by the position sensor 170 during one revolution of the impeller 20, thereby causing the position sensor 170 to generate a revolution marker signal value Ps.

As mentioned above, the position sensor 170 may generate a position signal Ep having a sequence of impeller position signal values Ps for indicating momentary rotational positions of the impeller 20 when the impeller 20 rotates. With reference to tables 2-4 in this document, such a marker signal value Ps is illustrated as “1” in column #2 in tables 2-4.

When the rotating impeller is provided with one position marker device 180, the marker signal value Ps will be provided once per revolution. The marker signal value Ps is illustrated as “1” in column #2 in tables 2-4. Having L equidistant vanes 310 in the impeller and one position signal value Ps per revolution and a constant speed of rotation fROT it is possible to generate one virtual position signal Pc per vane, so that the total number of position signal values Ps, Pc are evenly distributed, as discussed above (See Figure 14G). Thus, a position signal Ps or Pc will occur at every n/L sample value position, as indicated in Table 3, when there are provided n time slots per revolution. In table 3, n=7680, and L=6, and thus there is provided a position signal Pc at every 1280 sample, the calculated position signals being indicated as 1C.

It is believed that the mutually equidistant positions of the vanes 310 is of importance for some embodiments of this disclosure when the marker signal value Ps, illustrated as “1” in column #2 in tables 2-4, is provided once per revolution and virtual position signal values Pc are generated in an evenly distributed manner such that a position signal P or Pc will occur at every n/L sample value position, as indicated in Table 3, when there are provided n time slots per revolution in a sequence of impeller position signal values for indicating momentary rotational positions of the impeller 20. In table 3 an actually detected revolution marker signal value Ps is reflected as “1” (see column #2, time slot “0” and time slot “7680” in table 3), and virtual position signal values Pc are reflected as “1C” (see column #2, time slot “0” and time slot “7680” in table 3).

This is believed to be of importance for some embodiments of this disclosure since the position markers 180 cause the generation of position reference signal values, and the vanes 310 are involved in the causing of a signal event, such as e.g. an amplitude peak value, in the vibration signal (See references SEA, SMD, Se(i), S(j), S(q) e.g. in figures 1 andl 5). Moreover, the temporal duration between the occurrence of a position reference signal value and the occurrence of a signal event in the vibration signal, caused by pulsation in the fluid material 30, may be indicative of an internal state of the pump, as discussed elsewhere in this disclosure.

Table 4 is an illustration of the first block of data, i.e. relating to Passage I, having n/L = 7680/6=1280 consecutive time slots. It is to be understood that if there is a constant speed phase (See Fig 9) for the duration of a complete revolution of the impeller 20, then each of the blocks I to VI (See table 3) will have the same appearance as Passage I being illustrated in table 4.

According to embodiments of this disclosure, with reference to column #03 in table 4, the vibration sample values S(i) are analyzed for detection of a vibration signal signature SFP. The vibration signal signature SFP may be manifested as a peak amplitude sample value Sp.

According to an example, with reference to column #03 in table 4, the vibration sample values S(i) are analyzed by a peak value detector for detection of a peak sample value Sp. With reference to table 5, the peak value analysis leads to the detection of a highest vibration sample amplitude value S(i). In the illustrated example, the vibration sample amplitude value S(i=760) is detected to hold a highest peak value Sp.

Having detected the peak value Sp to be located in time slot 760, a temporal relation between the occurrence of the repetitive vibration signal amplitude component Sp and the occurrence of a position signal P(i) can be established. In table 5 the time slots carrying position signals P(i) are indicated as 0% and 100%, respectively, and all the slots in between may be labelled with their respective locations, as illustrated in column #02 in table 5. As illustrated in the example in col. #02 of table 5, the temporal location of slot number i = 760 is at a position 59% of the temporal distance between slot i=0 and slot i= 1280. Differently expressed, 760/1280= 0,59 = 59%

Consequently, the inventor concluded that the temporal relation between the occurrence of the repetitive vibration signal amplitude component SFP and the occurrence of a position signal P(i) may be used as an indication of the physical position of the event signature between two adjacent vanes 310 in the rotating impeller 20, such as between vanes 310A and 310B. In this connection reference is made to the discussion of figures 14A -14C, and 14D -14F, about the amplitude and the phase value of the detected pressure pulsation P54 and P77, respectively. As stated there, it appears as though the amplitude and the phase value of the detected pressure pulsation P54 and/or P77 is indicative of the current Operating Point 205 in relation to BEP (See also Figure 2B).

Accordingly, it appears to be of interest to establish the impeller position at the moment of occurrence of the peak value P54 and/or P77. Another way of expressing this is: In terms of the distance between two adjacent vane tips, 310A and 310B, it appears to be of interest to establish at what position, between the two adjacent vane tips, the highest peak value P54 and/or P77 occurs. This is because that position, i.e. the position at which the highest peak value occurs, appears to be indicative the current operating state of the pump. More specifically, the position at which the highest peak value occurs appears to be indicative the current operating state of the pump in relation to the Best Operating Point.

Accordingly, a position of the detected event signature 205 , expressed as a percentage of the distance between the tips of two adjacent vanes 310A, 310B (see figures 14A -14C, and 14D - 14F in conjunction with table 5), can be obtained by:

Counting a total number of samples (NB - NO = NB - 0 = NB =1280) from the first reference signal occurrence in sample number No = 0 to the second reference signal occurrence in sample number NB= 1280, and

Counting another number of samples (Np - No = Np -0 = Np) from the first reference signal occurrence at No = 0 to the occurrence of the peak amplitude value Sp at sample number Np, and generating said first temporal relation (Rr(r); TD; FI(r)) based on said another number Np and said total number NB. This can be summarized as:

Ri-(r) = RT(760)= (N_P - No ) / (NB - No) = (760 - 0) / (1280-0) = 0,59 = 59% Thus, information identifying a momentary operating point 205 may be generated by: Counting a total number of samples (NB) from the first reference signal occurrence to the second reference signal occurrence, and

Counting another number of samples (Np) from the first reference signal occurrence to the occurrence of the peak amplitude value Sp at sample number Np, and generating said first temporal relation (Rfyr); TD; FI(r)) based on a relation between said sample number Np and said total number of samples i.e. NB.

Since S= v*t, wherein S= distance, v= constant speed, and t is time, the temporal relation can be directly translated into a distance. Consequently, col. #02 of table 5, can be regarded as indicating the physical location of the event signature at a position 59% of the distance between vane 310A and vane 31 OB (see figure 14E, 14F and/or figure 14B, 14C in conjunction with col. #02 of table 5). Alternatively, col. #02 of table 5, can be regarded as indicating the physical location of the event signature at a percentage of the distance between the first static position Pl and the second static position P2 (See figure 14G in conjunction with col. #02 of table 5 and in view of figures 14E, 14F and/or figure 14B, 14C).

According to another example, with reference to table 6, the temporal relation between the occurrence of the repetitive vibration signal amplitude component Sp and the occurrence of a position signal P(i) can be regarded as a phase deviation or phase value FI, expressed in degrees.

Table 6

In fact, by using the position signal as a reference signal for the digital measurement signal

SMD, S(i), S(j), and adjusting the settings of a Fast Fourier Transformer in a certain manner, the Fast Fourier Transformer may be used for extracting the amplitude top value as well as the phase value, as discussed below. Consequently, col. #02 of table 6, can be regarded as indicating the location of the detected event signature 205, and/or indicating the physical location of the internal status indicator object 550 at a position 213,75 degrees of the distance between vane 310A and vane 310B when the total distance between vane 310A and vane 310B is regarded as 360 degrees (see figures 14A to 14F in conjunction with col. #02 of table 6).

When the phase angle parameter value FI, XI has a numerical value exceeding 180 degrees, it may be translated into a phase deviation value FIDEV, wherein

FIDEV = FI - 360

In this case, when

FI(r) = 360 * 760/1280 = 213,75 degrees then the corresponding phase deviation value FIDEV will be

FIDEV = FI - 360 = 213,75 - 360= -146,25 degrees

This is illustrated in Figure 19A.

Referring to figure 19A in conjunction with col. #02 of table 6, the phase angle FI appears to be indicative of a current operating point in relation to a Best Efficiency Point. In other words, the phase angle <b(r) = FI(r) may exhibit a predetermined value when the pump operates at BEP flow condition. When the phase angle <P(r) = FI(r) deviates from the predetermined value, that deviation appears to be indicative of operation away from BEP flow condition. In the example illustrated in figure 19A, the predetermined value was zero (0) degrees, so that the status indicator object 550BEP indicative of the pump operating at BEP flow condition exhibits a zero degree phase angle. Thus, the status indicator object 550BEP = 550(p+4) has a phase angle d>(r) = FI(r) = <P(p+4) = 0 degrees.

The physical location of the pulsation peak 205, when expressed as a part of the distance between two adjacent vanes 310, may be referred to as information identifying a momentary operating point 205 (compare figure 2B). In other words, this disclosure provides a manner of identifying information identifying a momentary operating point 205 in a centrifugal pump. Hence, this disclosure provides a manner of generating information indicative of the location of the detected event signature 205, when expressed as a proportion of the distance between two adjacent vanes 310 in a rotating impeller 20. With reference to figure 15A and/or figure 15B and figure 16 the internal status indicator object 550, and/or the operating point 205, 550 may be presented as a phase angle FI(r), as discussed in connection with figures 15 and 16 below. According to embodiments of this disclosure, the internal status indicator object 550 and/or the operating point 205, 550 can be presented as a percentage (see col. #02 of table 5 above). Moreover, according to embodiments of this disclosure, the internal status indicator object 550 and/or the operating point 205, 550 can be presented as a temporal duration, or as a part of a temporal duration. As discussed above, in connection with table 5, since S= V310T * t, wherein S= distance, V310T = the tangential speed of a vane tip, and t is time, the temporal relation can be directly translated into a distance. In this context it is noted that the tangential speed V310T of a vane depends on the angular velocity f_ROT of the impeller 20 and of the radius RMIC of the impeller 20 (See fig 14D, part II) .

Figure 15A is a block diagram illustrating an example of a status parameter extractor 450. The status parameter extractor 450 of figure 15A includes an impeller speed detector 500 that receives the digital vibration signal SMD, S(i) and the digital position signal (Pi). The impeller speed detector 500 may also be referred to as an impeller speed value generator 500. The impeller speed detector 500 may generate the three signals S(j), P(j) and f_ROTC) on the basis of the received digital vibration signal SMD, S(i) and the digital position signal (Pi). This may be achieved e.g. in the manner described above in relation to figures 7 to 13. In this connection it is noted that the three signals S(j), P(j) and fROT(j) may be delivered simultaneously, i.e. they all relate to the same time slot j. In other words, the three signals S(j), P(j) and f_ROTO) may be provided in a synchronized manner. The provision of signals, such as S(j), P(j) and Rcnfj), in a synchronized manner advantageously provides accurate information about temporal relations between signal values of the individual signals. Thus, for example, a speed value fRo?(j) delivered by the impeller speed value generator 500 is indicative of a momentary rotational speed of the impeller 20 at the time of detection of the amplitude value S(j).

It is noted that the signals S(j) and P(j), delivered by the impeller speed value generator 500, are delayed in relation to the signals S(i) and (Pi) received by the impeller speed value generator 500. It is also noted that the signals S(j) and P(j) are equally delayed in relation to the signals S(i) and (Pi), thus the temporal relation between the two has been maintained. In other words, the signals S(j) and P(j) are synchronously delayed. The impeller speed detector 500 may deliver a signal indicative of whether the speed of rotation has been constant for a sufficiently long time, in which case the signals S(j) and P(j) may be delivered to a Fast Fourier Transformer 510.

The variables OMAX, B_n, and L, should be set so as to render the variable NR a positive integer, as discussed above. According to an example, the above variables OMAX, B_n, and L, may be set by means of the Human Computer Interface, HCI, 210, 210S (See e.g. Fig 1 and/or fig. 5 and/or figure 15A). As mentioned above the resulting integer number NR may indicate the number of revolutions of the monitored centrifugal pump impeller 20 during which the digital signals S(j) and P(j) are analysed by the FFT 510. Thus, based on the settings of the variables OMAX, B_n, and L, the FFT 510 may generate the value NR, indicative of the duration of the analysis of a measurement session, and after a measurement session, the FFT 510 delivers a set of status value Sp(r) and FI(r).

The notion “r”, in status values Sp(r) and FI(r), indicates a point in time. It is to be noted that there may be a delay in time from the reception of a first pair of input signals S(j), P(j) at the inputs of the FFT 510 until the delivery of a corresponding pair of status values Sp(r) and FI(r) from the FFT 510. A pair of status values Sp(r) and FI(r) may be based on a temporal sequence of pairs of input signals S(j), P(j). The duration of the temporal sequence of pairs of input signals S(j), P(j) should include at least two successive position signal values P(j) = 1 and the corresponding vibration input signal values S(j).

The status values Sp(r) and FI(r) may also be referred to as CL and <J>L, respectively, as explained below.

For the purpose of conveying an intuitive understanding of this signal processing it may be helpful to consider the superposition principle and repetitive signals such as sinus signals. A sinus signal may exhibit an amplitude value and a phase value. In very brief summary, the superposition principle, also known as superposition property, states that, for all linear systems, the net response at a given place and time caused by two or more stimuli is the sum of the responses which would have been caused by each stimulus individually. Acoustic waves are a species of such stimuli. Also a vibration signal, such as the vibration signal SEA, SMD, S(j), S(r) including the signal signature is a species of such stimuli. In fact, the vibration signal SEA, SMD, S(j), S(r) including the signal signature SFP may be regarded as a sum of sinus signals, each sinus signal exhibiting an amplitude value and a phase value. In this connection, reference is made to the Fourier series (See Equation 5 below): n=oo

F(t) = £ C_n sin(ncot + <D_n ) (Eq. 5) n=0 wherein n=0 the average value of the signal during a period of time (it may be zero, but need not be zero), n=l corresponds to the fundamental frequency of the signal F(t), n=2 corresponds to the first harmonic partial of the signal F(t) co = the angular frequency i.e. (2*7T*f_ROT), fROT = the impeller speed of rotation expressed as periods per second, t= time,

<I>n= phase angle for the n:th partial, and

C_n = Amplitude for the n:th partial

It follows from the above Fourier series that a time signal may be regarded as composed of a superposition of a number of sinus signals.

An overtone is any frequency greater than the fundamental frequency of a signal.

In the above example, it is noted that the fundamental frequency will be fROT, i.e. the impeller speed of rotation, when the FFT 510 receives a marker signal value P(j)= 1 only one time per revolution of the impeller 20 (See e.g. figure 14G in conjunction with figures 5 and 15A and/or 15B).

Using the model of Fourier analysis, the fundamental and the overtones together are called partials. Harmonics, or more precisely, harmonic partials, are partials whose frequencies are numerical integer multiples of the fundamental (including the fundamental, which is 1 times itself).

With reference to Figure 15A and/or figure 15B and equation 5 above, the FFT 510 may deliver the amplitude value C_n(r) for n=L, i.e. CL (r) = Sp(r). The FFT 510 may also deliver phase angle for the partial (n=L), i.e. <bi.(r) = FI(r). Now consider an example when an impeller rotates at a speed of 10 revolutions per minute (rpm), the impeller having ten (10) vanes 310. A speed of 10 rpm renders one revolution every 6 seconds, i.e. f_ROT = 0,1667 rev/sec. The impeller having ten vanes (i.e. L=10) and running at a speed of f_ROT = 0, 1667 rev/sec renders a repetition frequency fR of 1 ,667 Hz for the signal relating to the vanes 310, since the repetition frequency fR is the frequency of order 10.

The position signal P(j), P(q) (see Figure 15A and/or figure 15B) may be used as a reference signal for the digital measurement signal S(j),S(r). According to some embodiments, when the FFT analyzer is configured to receive a reference signal, i.e. the position signal P(j), P(q), once per revolution of the rotating impeller 20, the setting of the FFT analyzer should fulfil the following criteria:

The integer value Oi is set to equal L, i.e. the number of vanes in the impeller 20, and the settable variables OMAX, and B_n are selected such that the mathematical expression Oi * B_n /OMAX becomes a positive integer. Differently expressed: When integer value Oi is set to equal L, then settable variables OMAX and B_n should be set to integer values so as to render the variable NR a positive integer, wherein NR = Oi * B_n / OMAX

OMAX is a maximum order; and

B_n is the number of bins in the frequency spectrum produced by the FFT, and

Oi is a frequency of interest, expressed as an integer in orders, and wherein fROT is the frequency of order 1, i.e. the fundamental frequency. In other words, the speed of rotation fROT of the impeller 20 is the fundamental frequency and L is the number of vanes in the impeller 20.

Using the above setting , i.e. integer value Oi is set to equal L, and with reference to Figure 15A and/or figure 15B and equation 5 above, the FFT 510 may deliver the amplitude value C_n for n=L, i.e. CL = Sp(r). The FFT 510 may also deliver phase angle for the partial (n=L), i.e. <bi. = FI(r).

Thus, according to embodiments of this disclosure, when the FFT 510 receives a position reference signal P(j), P(q) once per revolution of the rotating impeller 20, then the FFT analyzer can be configured to generate a peak amplitude value CL for a signal whose repetition frequency fR is the frequency of order L, wherein L is the number of vanes 310 in the rotating impeller 20. With reference to the discussion about equation 5 above in this disclosure, the amplitude of the signal whose repetition frequency fR is the frequency of order L may be termed C_n for n=L, i.e. CL. Referring to equation 5 and figure 15A and/or figure 15B, the amplitude value CL may be delivered as a peak amplitude value indicated as Sp(r) in figure 15A and/or figure 15B.

Again with reference to equation 5, above in this disclosure, the phase angle value r for the signal whose repetition frequency f is the frequency of order L may be delivered as a temporal indicator value, the temporal indicator value being indicative of a temporal duration TDI between occurrence of an detected event signature and occurrence of a rotational reference position of said rotating impeller.

Hence, according to embodiments of this disclosure, when the FFT 510 receives a position reference signal P(j), P(q) once P^er revolution of the rotating impeller 20, then the FFT analyzer can be configured to generate a phase angle value i for a signal whose repetition frequency f is the frequency of order L, wherein L is the number of vanes 310 in the rotating impeller 20.

Hence, using the above setting, i.e. integer value Oi being set to equal L, and with reference to Figure 15A and/or figure 15B and equation 5 above, the FFT 510 may generate the phase angle value L.

With reference to Figure 15A and/or figure 15B in conjunction with figure 1, the status values Sp(r) = CL and FI(r) = , may be delivered to the Human Computer Interface (HCI) 210 for providing a visual indication of the analysis result. As mentioned above, the analysis result displayed may include information indicative of an internal state of the centrifugal pump process for enabling the operator 230 to control the centrifugal pump.

Figure 15B is a block diagram illustrating an example of a status parameter extractor 450. The example status parameter extractor 450 in figure 15B comprises an impeller speed detector 500, a speed variation compensatory decimator 470, a Time Synchronous Averager 471, and a Fast Fourier Transformer 510, FFT. In this disclosure the abbreviation TSA may be used for Time Synchronous Averager. The example status parameter extractor 450 may be the status parameter extractor 450 described in figure 15A with the addition of the time synchronous averager, TSA, 471. The TSA 471 is configured to receive measurement signal values S(q) and corresponding position signal values P(q) as delivered by the speed variation compensatory decimator 470. The received measurement signal values S(q) may be vibration signal values S(q) or other measurement signal values S(q) indicative of the fluid pulsation.

The TSA 471 is configured to receive measurement signal values S(q) and corresponding position signal values P(q) relating to a plurality of revolutions or cycles, and to generate average measurement signal values S(t), wherein an average measurement signal value S(t) is based on a number M of measurement values detected at the same rotational position of the impeller 20.

As discussed elsewhere in this disclosure, the compensatory decimator 470 is configured to generate a decimated digital measurement signal SMDR such that the number Nv of measurement sample values per revolution of said rotating impeller is kept at a constant value, or at a substantially constant value, even when said rotational speed varies. Accordingly, when the compensatory decimator 470 delivers Nv measurement sample values per revolution of said rotating impeller, then every Nv:th measurement sample value relates to the same rotational position.

Thus, when Nv = 100, then the speed variation compensatory decimator 470 outputs one hundred (100) measurement signal values S(q) per revolution. Thus, when Nv = 100 and the TSA 471 is configured to generate an individual average measurement signal value STSA O as an average of M measurement signal values S(q), then the output average value STSA ) may be generated as:

STSAC) = ( S(q) + S(q+ Nv) + S(q+2*N_V ) )/ M SrsA(t) = ( S(q) + S(q+100) + S(q+200) )/ M

Thus, when the compensatory decimator 470 delivers Nv measurement sample values per revolution of said rotating impeller, then every Nv:th measurement sample value relates to the same rotational position. This advantageously means that the combination of the speed variation compensatory decimator 470 with the Time Synchronous Averager 471 results in Position Synchronous Averaging. In summary, a measurement sample value delivered from the Position Synchronous Averager 473 position output average value STSA(0 may be generated as:

wherein M is the number of impeller revolutions to be averaged, and Nv is the number of measurement sample values per revolution of the rotating impeller

For example, if M= 3, then the TSA 471 delivers STSA( wherein each value is based on three (3) measurement signal values S(q). Thus, it is to be understood that the signal values S(q), S(q+ Nv), and S(q+2* Nv) all represent the q:th position, i.e. to the same position at different revolutions. Thus, the TSA 471 delivers average signal values STSA(0 with the same number of elements as the number Nv of outputs per revolution provided by the speed variation compensatory decimator 470. For example, if a speed variation compensatory decimator 470 outputs Nv =100 (one hundred) measurement signal values S(q) per revolution, then the TSA 471 delivers Nv =100 (one hundred) average measurement signal values S(t) per revolution.

The combination of impeller speed detector 500, speed variation compensatory decimator 470, and time synchronous averager 471 allows for an output from the TSA 471 with measurement values averaged over several revolutions which advantageously reduces noise. It is to be noted that the TSA is configured to generate the averaged measurement values such that an average measurement value represents an average of a number of measurement values detected at the same rotational position of the impeller 20.

As illustrated in figure 15B, the output signals PTSA and STSA of the TSA 471 may be provided to the FFT 510.

In some examples, the output PTSA STSA of the TSA 471 is provided to the HCI 210.

In some examples, the HCI 210 is arranged to set the number of revolutions or cycles the TSA 471 is configured to average.

Information about the current internal state X of the mill 10 may be conveyed by one or more internal state values such that it intuitively makes sense to an operator 230 of the mill 10.

Figure 16 is an illustration of an example of a visual indication of an analysis result.

According to an example, the visual indication of the analysis result may include the provision of a polar coordinate system 520. A polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a reference point 530 and an angle from a reference direction 540. The reference point 530 (analogous to the origin of a Cartesian coordinate system) is called the pole 530, and the ray from the pole in the reference direction is the polar axis. The distance from the pole is called the radial coordinate, radial distance or simply radius, and the angle is called the angular coordinate, polar angle, or azimuth.

According to an example, the amplitude value Sp(r) is used as the radius, and the temporal relation value FI(r), <T>(r), TD is used as the angular coordinate.

In this manner an internal status of the monitored centrifugal pump may be illustrated by providing an internal status indicator object 550 on the display 210S (Figure 16 in conjunction with fig. 1). Figure 16 in conjunction with fig. 1 and figure 14 may be useful for understanding the following example.

Hence, an example relates to an electronic centrifugal pump monitoring system 150, 210S for generating and displaying information relating to a pumping process in a centrifugal pump 10 having an impeller 20 that rotates around an axis 60 at a speed of rotation fROT for causing fluid material 30 to exit the pump outlet 66. The example monitoring system 150 includes: a computer implemented method of representing an internal state of said pumping process in said centrifugal pump on a screen display 210S, the method comprising: displaying on said screen display 210S a polar coordinate system 520, said polar coordinate system 520 having a reference point (O, 530), and a reference direction (0°, 360°, 540); and a first internal status indicator object (550, Spi, TDI), indicative of said internal state of said pumping process, at a first radius (Sp(r), Spi) from said reference point (O) and at a first polar angle (FI(r), >(r), TD, TDI) in relation to said reference direction (0°,360°, 540), said first radius (X2(r) Sp(r), Spi) being indicative of an amplitude of detected fluid pulsation, and said first polar angle being indicative of a

direction of deviation of the current operating point 205 from a current Best Efficiency operating Point. The first polar angle may also be indicative of a

position of the detected event signature 205 between two vanes 310 in the rotating impeller 20.

As mentioned above, the status parameter extractor 450 may be configured to generate successive pairs of the status values Sp(r) and FI(r). The status parameter extractor 450 may also generate time derivative values of the status values Sp(r) and FI(r), respectively. This may be done e.g. by subtracting a most recent previous status value Sp(r-l) from the most recent status value Sp(r) divided by the temporal duration between the two values. Similarly a numerical derivative of the internal status value FI may be achieved. Thus, derivative values dSp(r) and dFI(r) may be generated. The derivative values dSp(r) and dFI(r) may be used for indicating movement of the first internal status indicator object (550, Spi, TDI).

Figures 17 and 18 are illustrations of another example of a visual indication of an analysis result. With reference to figures 17 and 18 the above mentioned derivative values may be used for displaying, on said screen display 210S, an arrow 560 originating at the position of the first internal status indicator object (550, Spi, TDI) and having an extension that depends on the magnitude of the derivative values. In other words, the absence of an arrow 560 means that the internal status is stable, not having changed for the temporal duration. The arrow 560 in figure 18 is longer than the arrow 560 in figure 17, thereby indicating a faster ongoing change of the internal status of the pump represented in figure 18 than that of the pump represented in figure 17.

Figure 19A is an illustration of yet another example of a visual indication of an analysis result in terms of internal status of the centrifugal pump 10. The example visual indication analysis result of figure 19A is based on the polar coordinate system 520, as disclosed above in connection with figure 16.

A most recent internal status indicator object 550(r) indicates a current internal status of the pump 10. Another internal status indicator object 55O(r-l) indicates a most recent previous internal status of the pump 10.

An internal status indicator object 550(1), indicates an internal status of the pump 10 at a very low flow rate, far below BEP. It is noted that when starting up a centrifugal pump, the flow will initially be very low. With reference to figure 19A, a gradually increasing flow, as it nears to the BEP flow, is indicated by a gradually closer position of the internal status indicator object 550(1) to the polar coordinate reference point (O, 530) at origin.

In this manner, the current internal status of the centrifugal pump 20 may be represented and visualized such that it intuitively makes sense to an operator 230 of the pump system 5. It is to be noted that, whereas the display of a single internal status indicator object 550, as shown in figure 16, represents a current internal status, or a latest detected internal status of the pump 10, the display of a temporal progression of internal status indicator objects ranging from an initial status 550(1) via intermediate states, such as 550(p), 550(p+ 1 ) and 550(r-l) to 550(r), as shown in figure 19A, represents a current internal status 550(r) as well as a history of several earlier internal states of the pump 10. In figure 19A the most recent earlier state is referenced as 550(r- 1 ). Some of the other earlier internal states illustrated in figure 19A are shown as internal status indicator objects 550(p+4), 550(p+l), 550(p), and 550(1). The internal status indicator object 550(p+4) is shown very close to origin and it illustrates operation of the pump at the Best Efficiency Point of operation 550BEP or operation of the pump very near the Best Efficiency Point of operation.

With reference to figure 19A in conjunction with figure 16 and the corresponding description above, it is noted that figure 19A provides a clear indication of the advantageous and useful information provided by the data generated in accordance with methods disclosed in this disclosure, such as the internal status indicator object 550. It is noted that the internal status indicator object 550 is indicative of said internal state of said pumping process.

In particular, it is noted that the polar angle Xl(r), FI(r), (r), TD, TDI is indicative of a direction of deviation of the current operating point 205 from a current Best Efficiency operating Point.

In this connection, it is noted that the Best Efficiency operating Point of a pump, when connected to a fluid system 52, can change e.g. due to a change in the backpressure from the fluid system 52. The data generated in accordance with methods disclosed in this disclosure, such as the polar angle X I (r), FI(r) will advantageously provide very accurate information about the current operating point, and - when current operating point 205, 550 deviates from BEP - the polar angle XI (r), FI(r) will provide information about the direction of deviation of the current operating point 205, 550 from a current Best Efficiency operating Point.

In summary, useful information provided by the data generated in accordance with methods disclosed in this disclosure, includes an amplitude value Sp(r), Spi that is indicative of detected fluid pulsation associated with the pump 10 during operation. Thus, the amplitude value Sp(r), Spi is indicative of said internal state of said pumping process in terms of current fluid pulsation amplitudes.

Moreover, the useful information provided by the data generated in accordance with methods disclosed in this disclosure, includes a polar angle value Xl(r), FI(r) that may be indicative of a current deviation from the current BEP.

An observation, based on this type of measurements on a number of centrifugal pumps 10 coupled to piping systems 40 and fluid material consumers 50, is that the detected polar angle (XI (r), FI(r), (r), TD, TDI) appears to always have a phase shift of approximately 180 degrees when internal status indicator object 550 and/or the operating point 205, 550 shifts from an operating point below BEP to operating point above BEP, or vice versa. Additionally, the amplitude X2(r) Sp(r), Spi of detected fluid pulsation is at its minimum when the pump 10 operates at BEP flow, as discussed elsewhere in this disclosure e.g. in connection with Figure 14A.

Accordingly, the radius (X2(r) Sp(r), SPI) is indicative of an amplitude of detected fluid pulsation, and said first polar angle exhibits a phase shift of approximately 180

degrees, when the internal status indicator object 550 and/or the operating point 205, 550 changes from below BEP to above BEP, or vice versa. Accordingly, it appears to be desirable to control the pump such that a current internal status 550(r) is shifted towards the reference point (O, 530) at origin, in the polar plot according figures, or to a position which is as close as possible the reference point (O, 530).

Moreover, it appears as though, for any pump/system combination, controlling the pump such that the internal status indicator object 550 is steered as close as possible to the reference point (O, 530) in the polar plot, renders operation with the best possible efficiency and/or with the lowest possible pulsation.

Thus, it is concluded, that the provision of the status indicator values X2(r), Sp(r) and XI (r), FI(r) enables an improvement in ability to control fluid systems. In particular, the methods and illustrations herein disclosed provide very clear and interpretable measurement results, that enable greatly improved operation of pumps 10 and fluid systems 5, 40,50. As noted above, the parameter value XI may be indicative of a direction of deviation of the current operating point 205 from a current Best Efficiency operating Point (BEP). In this connection, it is noted that the fluid system flow-pressure characteristic may vary during operation, and thus the BEP may also change (See figure 2B). Accordingly, the methods and illustrations herein disclosed enable agility in terms of providing a manner of detecting the current operating point 205 in relation to the current BEP.

Another observation, based on this type of measurements on a number of centrifugal pumps 10 coupled to piping systems 40 and fluid material consumers 50, is that an individual pump/system combination appear to create a unique pattern of movement of its internal status indicator object 550.

Figures 19B, 19C and 19D are illustrations of a large number of internal status indicator objects relating to a pump 10 that has operated below BEP, as indicated by status indicator objects 550₁, 550₂, and 550₃, as well as at flow over BEP, as indicated by status indicator objects 550₄, 550₅, and 550₆. The cloudlike lumps of black dots are internal status indicator objects 550 collected during a long time and over a range of operating conditions.

Figure 19E is an illustration of a first time plot 570, 570A of the amplitude of a detected fluid pressure pulsation PFP in a centrifugal pump 10 having four impeller vanes 310 (See figure 19E in conjunction with figure 2A). The time plot in figure 19E is a polar plot, i.e. time is progressing in a clockwise angular direction and 360 degrees corresponds to a full revolution of the impeller 20. The radius at a certain point of the plot depends on the detected amplitude of the detected fluid pressure pulsation PFP.

The amplitude time plot 570, 570A in figure 19E, relating to four impeller vanes, exhibits four highest amplitude peaks, and four lowest amplitude peaks. It is to be noted that the angular positions of the amplitude peaks change, depending on the current operating state OP of the pump (See discussion in connection with figures 14A to 14F and 16 to 19B). Thus, the amplitude time plot 570 in a pump having L impeller vanes, exhibits L highest amplitude peaks, and L lowest amplitude peaks, wherein L is the number of vanes on the impeller in the pump 10. Thus, the amplitude time plot 570 appears to exhibit one signal signature per vane 310. A single signal signature appears to exhibit one highest amplitude peak, and one lowest amplitude peak.

Figure 19F is another illustration of a second time plot 570, 570B of the amplitude of a detected fluid pressure pulsation PFP in the same centrifugal pump 10 as discussed above in connection with Figure 19E. The second time plot 570, 570B was recorded at another time as compared to the first time plot 570, 570A of figure 19E.

The inventor concluded, when studying the shape of the amplitude time plot 570 during a long time, and under various operating conditions, that the shape of the amplitude time plot 570 changed dependent on an internal state X of the centrifugal pump 10.

The inventor concluded that the shape of the amplitude time plot 570 appears to be indicative of an internal state X of the pump 10. During normal operation, the L individual signal signatures 572i, 5722, 5723, 5724, 572L, appears to exhibit a uniform shape, or a substantially uniform shape, as illustrated by figure 19E.

However, as illustrated in figure 19F, the shape of an individual signal signature 572B3 may exhibit a shape that deviates from the shape of the other signal signatures.

The inventor concluded that the shape of the amplitude time plot 570B appears to indicate that a physical feature associated with at least one of the vanes 310 or a physical feature associated with at least one of the impeller passages 320 deviates from normal. In other words, when an individual signal signature exhibits a shape that deviates from the shape of the other signal signatures that deviation appears to indicate that a physical feature associated with at least one of the vanes 310, or a physical feature associated with at least one of the impeller passages 320, deviates from normal. It is believed that such a deviation may be indicative of a damage to the surface of vane 310, or alternatively such a deviation may be indicative of an impeller passage 320 being partly clogged by a particle that got stuck in the impeller passage 320.

An example of variable speed phase status parameter extractor As mentioned above, the analysis of the measurements data is further complicated if the centrifugal pump impeller 20 rotates at a variable rotational speed fROT. In fact, it appears as though even very small variations in rotational speed of the impeller may have a large adverse effect on detected signal quality in terms of smearing. Hence, a very accurate detection of the rotational speed ( OT of the pump impeller 20 appears to be of essence, and an accurate compensation for any speed variations appears to also be of essence.

With reference to figure 15A and/or figure 15B, the impeller speed detector 500 may deliver a signal indicating when the speed of rotation varies, as discussed in connection with figure 9. Referring again to figure 15A and/or figure 15B, the signals S(j) and P(j) as well as the speed value fROT(j) may be delivered to a speed variation compensatory decimator 470. The speed variation compensatory decimator 470 may also be referred to as a fractional decimator. The decimator 470 is configured to decimate the digital measurement signal SMD based on the received speed value fRoi(j). According to an example, the decimator 470 is configured to decimate the digital measurement signal SMD by a variable decimation factor D, the variable decimation factor D being adjusted during a measuring session based on the variable speed value f_ROT(J). Hence, the compensatory decimator 470 is configured to generate a decimated digital measurement signal SMDR such that the number of sample values per revolution of said rotating impeller is kept at a constant value, or at a substantially constant value, when said rotational speed varies. According to some embodiments, the number of sample values per revolution of said rotating impeller is considered to be a substantially constant value when the number of sample values per revolution varies less than 5 %. According to a preferred embodiment, the number of sample values per revolution of said rotating impeller is considered to be a substantially constant value when the number of sample values per revolution varies less than 1 %. According to a most preferred embodiment, the number of sample values per revolution of said rotating impeller is considered to be a substantially constant value when the number of sample values per revolution varies by less than 0,2 %.

Thus, the Figure 15A and/or figure 15B embodiment includes the fractional decimator 470 for decimating the sampling rate by a decimation factor D = N/U, wherein both U and N are positive integers. Hence, the fractional decimator 470 advantageously enables the decimation of the sampling rate by a fractional number. Hence, the speed variation compensatory decimator 470 may operate to decimate the signals S(j) and P(j) and fROT(j) by a fractional number D = N/U. According to an embodiment the values for U and N may be selected to be in the range from 2 to 2000. According to an embodiment the values for U and N may be selected to be in the range from 500 to 1500. According to yet another embodiment the values for U and N may be selected to be in the range from 900 to 1100. In this context it is noted that the background of the term “fraction” is as follows: A fraction (from Latin fractus, "broken") represents a part of a whole or, more generally, any number of equal parts. In positive common fractions, the numerator and denominator are natural numbers. The numerator represents a number of equal parts, and the denominator indicates how many of those parts make up a unit or a whole. A common fraction is a numeral which represents a rational number. That same number can also be represented as a decimal, a percent, or with a negative exponent. For example, 0.01, 1%, and 10-2 are all equal to the fraction 1/100. Hence, the fractional number D = N/U may be regarded as an inverted fraction.

Thus, the resulting signal SMDR, which is delivered by fractional decimator 470, has a sample rate of

where fs is the sample rate of the signal SMD received by fractional decimator 470.

The fractional value U/N is dependent on a rate control signal received on an input port 490. The rate control signal may be a signal indicative of the speed of rotation fROT of the rotating impeller.

The variable decimator value D for the decimator may be set to D= fs/ fsR, wherein fs is the initial sample rate of the A/D converter, and fsR is a set point value indicating a number of samples per revolution in the decimated digital measurement signal SMDR. For example, when there are twelve (12) vanes in the impeller to be monitored, the set point value fsR may be set to 768 samples per revolution, i.e. the number of samples per revolution is set to fsr in the decimated digital measurement signal SMDR. The compensatory decimator 470, 470B is configured to generate a position signal P(q) at a regular interval of the decimated digital measurement signal SMDR, the regular interval being dependent on the set point value fsR. For example, when fsR is set to 768 samples per revolution, a position signal P(q) may be delivered once with every 768 sample of the decimated measurement signal S(q). In this manner the position signal P(q) is indicative of a static angular position, in a manner similar to the position signal value Ps discussed above.

According to another example, the compensatory decimator 470, 470B is configured to generate a position signal P(q) once per L divided by fsR samples of the decimated measurement signal S(q). Thus, a position signal P(q) may be delivered at a regular interval of the decimated digital measurement signal SMDR, the regular interval being L/fsR. In this manner the position signal P(q) is indicative of L static angular positions, in a manner similar to the virtual position signal values Pc discussed above.

Hence, the sampling frequency fsR, also referred to as fsR2, for the output data values R(q) is lower than input sampling frequency fs by a factor D. The factor D can be set to an arbitrary number larger than 1, and it may be a fractional number, as discussed elsewhere in this disclosure. According to preferred embodiments the factor D is settable to values between 1 ,0 to 20,0. In a preferred embodiment the factor D is a fractional number settable to a value between about 1,3 and about 3,0. The factor D may be obtained by setting the integers U and N to suitable values. The factor D equals N divided by U:

D = N/U

According to an embodiment, the integers U and N are settable to large integers in order to enable the factor D=N/U to follow speed variations with a minimum of inaccuracy. Selection of variables U and N to be integers larger than 1000 renders an advantageously high accuracy in adapting the output sample frequency to tracking changes in the rotational speed of the impeller 20. So, for example, setting N to 500 and U to 1001 renders D=2,002.

The variable D is set to a suitable value at the beginning of a measurement and that value is associated with a certain speed of rotation of a rotating part to be monitored. Thereafter, during measuring session, the fractional value D is automatically adjusted in response to the speed of rotation of the rotating part to be monitored so that the output signal SMDR provides a substantially constant number of sample values per revolution of the rotating impeller. Figure 20 is a block diagram of an example of compensatory decimator 470. This compensatory decimator example is denoted 470B.

Compensatory decimator 470B may include a memory 604 adapted to receive and store the data values S(j) as well as information indicative of the corresponding speed of rotation fROT of the monitored rotating impeller . Hence the memory 604 may store each data value S(j) so that it is associated with a value indicative of the speed of rotation fRor(j) of the monitored impeller at time of detection of the sensor signal SEA value corresponding to the data value S(j). The provision of data values S j) associated with corresponding speed of rotation values fROTfj) is described with reference to Figures 7 - 13 above.

Compensatory decimator 470B receives the signal SMD, having a sampling frequency fsRi, as a sequence of data values S(j), and it delivers an output signal SMDR, having a reduced sampling frequency fsR, as another sequence of data values R(q) on its output 590.

Compensatory decimator 470B may include a memory 604 adapted to receive and store the data values S(j) as well as information indicative of the corresponding speed of rotation fROT of the monitored rotating impeller. Memory 604 may store data values S(j) in blocks so that each block is associated with a value indicative of a relevant speed of rotation of the monitored impeller, as described below in connection with Figure 21.

Compensatory decimator 470B may also include a compensatory decimation variable generator 606, which is adapted to generate a compensatory value D. The compensatory value D may be a floating number. Hence, the compensatory number can be controlled to a floating number value in response to a received speed value AROT so that the floating number value is indicative of the speed value f_ROT with a certain inaccuracy. When implemented by a suitably programmed DSP, as mentioned above, the inaccuracy of floating number value may depend on the ability of the DSP to generate floating number values.

Moreover, compensatory decimator 470B may also include a FIR filter 608. In this connection, the acronym FIR stands for Finite Impulse Response. The FIR filter 608 is a low pass FIR filter having a certain low pass cut off frequency adapted for decimation by a factor DMAX. The factor DMAX may be set to a suitable value, e.g. 20,000. Moreover, compensatory decimator 470B may also include a filter parameter generator 610. Operation of compensatory decimator 470B is described with reference to Figures 21 and 22 below.

Figure 21 is a flow chart illustrating an embodiment of a method of operating the compensatory decimator 470B of Figure 20.

In a first step S2000, the speed of rotation fROT of the impeller to be monitored is recorded in memory 604 (Fig 20 & 21), and this may be done at substantially the same time as measurements begin. According to another example the speed of rotation of the impeller to be monitored is surveyed for a period of time. The highest detected speed fROTmax and the lowest detected speed fROTmm may be recorded, e.g. in memory 604 (Fig 20 & 21).

In step S2010, the recorded speed values are analysed, for the purpose of establishing whether the speed of rotation varies.

In step S2020, the user interface 210, 210S displays the recorded speed value f_ROT or speed values fROTmin, fROTmax, and requests a user to enter a desired order value Oi. As mentioned above, the impeller rotation frequency fROT is often referred to as ’’order 1”. The interesting signals may occur about ten times per impeller revolution (Order 10). Moreover, it may be interesting to analyse overtones of some signals, so it may be interesting to measure up to order 100, or order 500, or even higher. Hence, a user may enter an order number Oi using user interface 210, 21 OS.

In step S2030, a suitable output sample rate fsR is determined. The output sample rate fsR may also be referred to as fsR2 in this disclosure. According to an embodiment output sample rate fsR is set to fsR = C * Oi * fROTmin wherein

C is a constant having a value higher than 2,0

Oi is a number indicative of the relation between the speed of rotation of the monitored impeller and the repetition frequency of the signal to be analysed. fROTmin is a lowest speed of rotation of the monitored impeller to expected during a forthcoming measurement session. According to an embodiment the value fROTmin is a lowest speed of rotation detected in step S2020,as described above. The constant C may be selected to a value of 2,00 (two) or higher in view of the sampling theorem. According to embodiments of the present disclosure the Constant C may be pre-set to a value between 2,40 and 2,70.

According to an embodiment the factor C is advantageously selected such that 100*C/ 2 renders an integer. According to an embodiment the factor C may be set to 2,56. Selecting C to 2,56 renders 100* C = 256 = 2 raised to 8.

In step S2050, a compensatory decimation variable value D is determined. When the speed of rotation of the impeller to be monitored varies, the compensatory decimation variable value D will vary in dependence on momentary detected speed value.

According to an embodiment, a maximum compensatory decimation variable value DMAX is set to a value of and a minimum compensatory decimation variable

value D IN is set to 1,0. Thereafter a momentary real time measurement of the actual speed value fROT is made and a momentary compensatory value D is set accordingly. fROT is value indicative of a measured speed of rotation of the rotating impeller to be monitored

In step S2060, the actual measurement is started, and a desired total duration of the measurement may be determined. The total duration of the measurement may be determined in dependence on a desired number of revolutions NR of the monitored impeller .

When measurement is started, a digital signal S D is delivered to input 480 of the compensatory decimator. In the following the signal S D is discussed in terms of a signal having sample values S(j), where j is an integer.

In step S2070, record data values S(j) in memory 604, and associate each vibration data value S(j) with a speed of rotation value fROT(j).

In a subsequent step S2080, analyze the recorded speed of rotation values, and divide the recorded data values S(j) into blocks of data dependent on the speed of rotation values. In this manner a number of blocks of block of data values S(j) may be generated, each block of data values S(j) being associated with a speed of rotation value . The speed of rotation value indicates the speed of rotation of the monitored impeller , when this particular block data values S j) was recorded. The individual blocks of data may be of mutually different size, i.e. individual blocks may hold mutually different numbers of data values S(j).

If, for example, the monitored rotating impeller first rotated at a first speed fRon during a first time period, and it thereafter changed speed to rotate at a second speed f_ROT2 during a second, shorter, time period, the recorded data values S(j) may be divided into two blocks of data, the first block of data values being associated with the first speed value f_ROTI , and the second block of data values being associated with the second speed value f_ROT2. In this case the second block of data would contain fewer data values than the first block of data since the second time period was shorter.

According to an embodiment, when all the recorded data values S(j) have been divided into blocks, and all blocks have been associated with a speed of rotation value, then the method proceeds to execute step S2090.

In step S2090, select a first block of data values S(j), and determine a compensatory decimation value D corresponding to the associated speed of rotation value f_ROT. Associate this compensatory decimation value D with the first block of data values S(j). According to an embodiment, when all blocks have been associated with a corresponding compensatory decimation value D, then the method proceeds to execute step S2100. Hence, the value of the compensatory decimation value D is adapted in dependence on the speed fROT-

In step S2100, select a block of data values S(j) and the associated compensatory decimation value D, as described in step S2090 above.

In step S2110, generate a block of output values R in response to the selected block of input values S and the associated compensatory decimation value D. This may be done as described with reference to Figure 22.

In step S2120, Check if there is any remaining input data values to be processed. If there is another block of input data values to be processed, then repeat step S2100. If there is no remaining block of input data values to be processed then the measurement session is completed. Figures 22A, 22B and 22C illustrate a flow chart of an embodiment of a method of operating the compensatory decimator 470B of Figure 20.

In a step S2200, receive a block of input data values S(j) and an associated specific compensatory decimation value D. According to an embodiment, the received data is as described in step S2100 for Figure 21 above. The input data values S(j) in the received block of input data values S are all associated with the specific compensatory decimation value D.

In steps S2210 to S2390 the FIR-filter 608 (See Fig. 20) is adapted for the specific compensatory decimation value D as received in step S2200, and a set of corresponding output signal values R(q) are generated. This is described more specifically below.

In a step S2210, filter settings suitable for the specific compensatory decimation value D are selected. As mentioned in connection with Figure 20 above, the FIR filter 608 is a low pass FIR filter having a certain low pass cut off frequency adapted for decimation by a factor DMAX. The factor DMAX may be set to a suitable value, e.g. 20.

A filter ratio value FR is set to a value dependent on factor D AX and the specific compensatory decimation value D as received in step S2200. Step S2210 may be performed by filter parameter generator 610 (Fig. 20).

In a step S2220, select a starting position value x in the received input data block s(j). It is to be noted that the starting position value x does not need to be an integer. The FIR filter 608 has a length FLENGTH and the starting position value x will then be selected in dependence of the filter length FLENGTH and the filter ratio value FR. The filter ratio value FR is as set in step S2210 above. According to an embodiment, the starting position value x may be set to x:= FLENGTH/ FR.

In a step S2230 a filter sum value SUM is prepared, and set to an initial value, such as e.g. SUM := 0,0

In a step S2240 a position) in the received input data adjacent and preceding position x is selected. The position j may be selected as the integer portion of x. In a step S2250 select a position Fpos in the FIR filter that corresponds to the selected position j in the received input data. The position Fpos may be a compensatory number. The filter position Fpos, in relation to the middle position of the filter, may be determined to be

Fpos = [(x-j) * FR] wherein FR is the filter ratio value.

In step S2260, check if the determined filter position value Fpos is outside of allowable limit values, i.e. points at a position outside of the filter. If that happens, then proceed with step S2300 below. Otherwise proceed with step S2270.

In a step S2270, a filter value is calculated by means of interpolation. It is noted that adjacent filter coefficient values in a FIR low pass filter generally have similar numerical values.

Hence, an interpolation value will be advantageously accurate. First an integer position value IFpos is calculated:

IFpos := Integer portion of Fpos

The filter value Fval for the position Fpos will be:

Fval = A(IFpos) + [A(IFpos+l) - A(IFpos)] * [Fpos - IFpos] wherein A(IFpos) and A(IFpos+l) are values in a reference filter, and the filter position Fpos is a position between these values.

In a step S2280, calculate an update of the filter sum value SUM in response to signal position j:

SUM := SUM + Fval * S(j)

In a step S2290 move to another signal position:

Setj :=j-l

Thereafter, go to step S2250.

In a step 2300, a position] in the received input data adjacent and subsequent to position x is selected. This position] may be selected as the integer portion of x. plus 1 (one), i.e. j:= 1 + Integer portion of x In a step S2310 select a position in the FIR filter that corresponds to the selected position j in the received input data. The position Fpos may be a compensatory number. The filter position Fpos, in relation to the middle position of the filter, may be determined to be

Fpos = [(j-x) * FR] wherein FR is the filter ratio value.

In step S2320, check if the determined filter position value Fpos is outside of allowable limit values, i.e. points at a position outside of the filter. If that happens, then proceed with step S2360 below. Otherwise proceed with step S2330.

In a step S2330, a filter value is calculated by means of interpolation. It is noted that adjacent filter coefficient values in a FIR low pass filter generally have similar numerical values.

IFpos := Integer portion of Fpos

The filter value for the position Fpos will be:

Fval (Fpos) = A(IFpos) + [A(IFpos+l) - A(IFpos)] * [Fpos - IFpos] wherein A(IFpos) and A(IFpos+l) are values in a reference filter, and the filter position Fpos is a position between these values.

In a step S2340, calculate an update of the filter sum value SUM in response to signal position j:

SUM := SUM + Fval * S(j)

In a step S2350 move to another signal position:

Setj :=j+l

Thereafter, go to step S2310.

In a step S2360, deliver an output data value R(j). The output data value R(j) may be delivered to a memory so that consecutive output data values are stored in consecutive memory positions. The numerical value of output data value R(j) is:

R(j) := SUM In a step S2370, update position value x: x := x + D

In a step S2380, update position value j j :=j+l

In a step S2390, check if desired number of output data values have been generated. If the desired number of output data values have not been generated, then go to step S2230. If the desired number of output data values have been generated, then go to step S2120 in the method described in relation to Figure 21.

In effect, step S2390 is designed to ensure that a block of output signal values R(q), corresponding to the block of input data values S received in step S2200, is generated, and that when output signal values R corresponding to the input data values S have been generated, then step S2120 in Fig.21 should be executed.

The method described with reference to Figure 22 may be implemented as a computer program subroutine, and the steps S2100 and S21 10 may be implemented as a main program.

Figure 23 is a block diagram that illustrates another example of a status parameter extractor 450, referred to as status parameter extractor 450C. The status parameter extractor 450C may include a vibration event signature detector and position signal value detector and a relation generator, as discussed below. The vibration event signature detector may be embodied by a peak detector, as discussed below.

Accordingly, Figure 23 is a block diagram illustrating an example of a part of the analysis apparatus 150. In the Figure 23 example, some of the functional blocks represent hardware and some of the functional blocks either may represent hardware, or may represent functions that are achieved by running program code on the data processing device 350, as discussed in connection with figures 3 and 4. The apparatus 150 in figure 5 shows an example of the analysis apparatus 150 shown in figure 1 and/or figure 3. The parameter extractor 450 in the apparatus 150 of figure 5 may embodied by the status parameter extractor 450C of Figure 23.

According to aspects of the solution disclosed in this document, reference position signal values Ep, 1 , 1C, Ps, Pc are generated at L predetermined rotational positions of the rotatable impeller 20, the L predetermined rotational positions following a pattern that reflects the angular positions of the L vanes 310 in the impeller 20. The provision of such reference position signal values Ep, 1,1C together with the provision of vibration event signature detection in a manner as herein disclosed, makes it possible to generate data indicative of a current operating point 205, 550 in relation to a best efficiency operating point in an advantageously accurate manner.

Although it has been exemplified with vanes 310 that are positioned in an equidistant pattern, i.e. evenly distributed in the impeller 20, this solution is also operable with other patterns of angular positions of the L vanes 310 in the impeller 20. When other patterns of angular positions of the L vanes 310 in the impeller is used, it is of importance that the reference position signal values Ep, 1 , 1 C are generated at L predetermined rotational positions of the impeller 20, the L predetermined rotational positions following a pattern that reflects the angular positions of the L vanes 310 in the impeller 20.

With reference to figure 5, the A/D converter 330 may be configured to deliver a sequence of pairs of vibration measurement values S(i) associated with corresponding position signal values P(i) to the status parameter extractor 450. The status parameter extractor 450 is configured to generate one or more parameter values XI, X2, X3,..., Xm, where the index m is a positive integer.

The status parameter extractor 450 may be embodied e.g. as discussed in connection with figure 15A and/or figure 15B. Alternatively, the status parameter extractor 450 may be embodied e.g. as discussed in connection with Figure 23.

The status parameter extractor 450C, of Figure 23, is adapted to receive a sequence of measurement values S(i) and a sequence of positional signals P(i), together with temporal relations there-between.

Thus, an individual vibration measurement value S(i) is associated with a corresponding position value P(i). Such a signal pair S(i) and P(i) are delivered to a memory 970. With reference to Figure 23, the status parameter extractor 450C comprises a memory 970.

The memory 970 may operate to receive data, in the form of a signal pair S(i) and P(i), so as to enable analysis of temporal relations between occurrences of events in the received signals. Columns #2 and #3 in Table 3 provide an illustration of an example of the data collected in the memory 970 during one full revolution of an impeller, when a position signal 1, 1C is provided six times per revolution, since there are L=6 vanes 310 in the impeller 20. Table 4 and table 5 provide more detailed information about example signal values in the first 1280 time slots of table 3.

The position signal 1 , 1 C may be generated by physical marker devices 180 an/or some position signals 1C may be virtual position signals. The time sequence of position signal sample values P(i), P(j), P(q)) should be provided at an occurrence pattern that reflects the angular positions of the vanes 310 in the impeller 20.

For example, when there are six (L= 6) equidistant vanes 310 in the impeller 20, the angular distance between any two adjacent vanes 310 is 60 degrees. This is since 360 degrees is one full revolution and, when L=6, the angular distance between any two adjacent vanes is 360/L = 360/6 = 60. Accordingly, the corresponding time sequence of position signal sample values P(i), representing a full revolution of the impeller 20, should include six (L= 6) position signal values 1, 1C with a corresponding occurrence pattern, as illustrated in table 3.

The status parameter extractor 450C further comprises a position signal value detector 980 and vibration event signature detector 990 . The vibration event signature detector 990 may be configured to detect a pressure pulsation event such as an amplitude peak value in the received sequence of measurement values S(i).

The output of the position signal value detector 980 is coupled to a START/STOP input 995 of a reference signal time counter 1010, and to a START input 1015 of an event signature time counter 1020. The output of the position signal value detector 980 may also coupled to a START/STOP input 1023 of vibration event signature detector 990 for indicating the start and the stop of the duration to be analyzed. Detector 990 transmits on its output when a position signal value 1 , 1 C is detected.

The vibration event signature detector 990 is configured to analyse all the sample values S(i) between two consecutive position signal values 1, 1C for detecting a highest peak amplitude value Sp therein. The vibration event signature detector 990 has a first output 1021 which is coupled to a STOP input 1025 of the event signature time counter 1020. The reference signal time counter 1010 is configured to count the duration between two consecutive position signal values 1, 1C, thereby generating a first reference duration value TREFI on an output 1030. This may be achieved, e.g. by reference signal time counter 1010 being a clock timer that counts the temporal duration between two consecutive position signal values 1, 1C. Alternatively, the reference signal time counter 1010 may count the number of time slots (See column #01 in table 3) between two consecutive position signal values 1, 1C. The reference signal time counter 1010 may be configured to deliver the first reference duration value TREFI, via the output 1030 to a speed value generator 1035. The speed value generator 1035 may be configured to generate data indicative of the rotational speed f_ROT of the impeller 20, based on the temporal duration between two consecutive position signal values 1, 1C, and data indicative of the number of position signal values 1, 1C per revolution.

The number of position signal values 1, 1C per revolution may be referred to as an occurrence frequency fREF of the repeating reference position signal value. Thus, the speed value generator 1035 may be configured to generate data indicative of the rotational speed f_ROT of the impeller 20, based on data indicative of the temporal duration between two consecutive position signal values 1, 1C, and data indicative of the occurrence frequency fREF of the repeating reference position signal value.

Thus, for example, when the position signal P(i) (See figure 23) includes one reference signal value per revolution of the impeller, then the rotational speed f oT of the impeller 20 is the inverse of the first reference duration value TREFI :

Alternatively, when the position signal P(i) (See figure 23) includes a first number L of reference signal values per revolution of the impeller, then the rotational speed fROT of the impeller 20 is the inverse of the first reference duration value TREFI multiplied with the inverse of the first number L:

Accordingly, if the first reference duration value TREFI is measured in seconds, then the rotational speed f_ROT of the impeller 20 will be generated as revolutions per second, RPS.

The speed value f_ROT of the impeller 20 constitutes internal state parameter X3, X3(r). Moreover, the status parameter extractor 450, 450C of figure 23 may also generate the fourth internal state parameter X4, X4(r) indicative of the impeller pass frequency. The impeller pass frequency X4, X4(r) may be generated by a pass frequency generator 1037 based on the rotational speed f_ROT and the number L of vanes on the relevant impeller. Inputs 1038 and 1039 for receiving the occurrence frequency IREF and the number L, respectively, may be provided, as illustrated in figure 23. According to an example, the Inputs 1038 and 1039 are integrated with user interface 210, 210S, 210B described elsewhere in this disclosure.

The impeller pass frequency X4, X4(r) may be generated by the pass frequency generator 1037 by multiplication of the rotational speed f_ROT value and the number L of vanes on the relevant impeller.

The event signature time counter 1020 is configured to count the duration from the occurrence of a position signal value 1, 1C to the occurrence of a pressure pulsation event such as an amplitude peak value. This may be attained in the following manner:

- The event signature time counter 1020 starts counting when receiving, on START input 1015, information that position signal value detector 980 detected an occurrence of a position signal value 1, 1C.

- The event signature time counter 1020 stops counting when receiving, on STOP input 1025, information that vibration event signature detector 990 detected a pressure pulsation event such as an amplitude peak value in the received sequence of measurement values S(i).

In this manner, the event signature time counter 1020 may be configured to count the temporal duration from the occurrence of a position signal value 1, 1C to the occurrence of an amplitude peak value. The temporal duration from the occurrence of a position signal value 1, 1C to the occurrence of an amplitude peak value is here referred to as an event phase duration value TEPD- The event phase duration value TEPD may be delivered on an output 1040. The output 1040 is coupled to an input of a relation generator 1050 so as to provide the event phase duration value TEPD to the relation generator 1050.

The relation generator 1050 also has an input coupled to receive the first reference duration value TREFI from the output 1030 of reference signal time counter 1010. The relation generator 1050 is configured to generate a relation value XI based on the received event phase duration value TEPD and the received first reference duration value TREFI . The relation value XI may also be referred to as R-r(r); TD; FI(r). The relation value XI may be generated L times per revolution of the impeller 20. Moreover, the L times generated relation values XI from a single revolution of the impeller may be averaged to generate one value Xl(r) per revolution of the impeller 20. In this manner, the status parameter extractor 450C may be configured to deliver an updated value Xl(r) once per revolution.

For the purpose of clarity, an example of a relation value XI is generated in the following manner: Please refer to column #03 in table 4 in conjunction with Figure 23: The vibration sample values S(i) are analyzed, by vibration event signature detector 990 , for the detection of a vibration signal signature SFP.

The vibration signal signature SFP may be manifested as a peak amplitude sample value Sp. With reference to table 6, the peak value analysis leads to the detection of a highest vibration sample amplitude value S(i). In the illustrated example, the vibration sample amplitude value S(i=760) is detected to hold a highest peak value Sp.

Having detected the peak value Sp to be located in time slot 760, a temporal relation value XI can be established.

The reference positions are indicated by data in column #02 in table 6. The reference positions are expressed as values for the phase angle FI, XI. As explained above in the disclosure relating to table 6, two position signal sample values P(i), carrying position signal values 1, 1C are expressed as phase angles 0 and 360 degrees, respectively, in column #02 in table 6. Consequently, column #02 in conjunction with column #03 of table 6, can be regarded as indicating the location of the detected event signature 205, and/or indicating the physical location of the internal status indicator object 550, at an angular position of 213,75 degrees (See column #03 of table 6 in conjunction with figure 16 and/or figure 19A). When the Best Operating Point is at an angular position of zero degrees, as in the example of figure 19A, the angular position of 213,75 degrees would indicate a deviation from BEP by 213,75 degrees. However, as discussed elsewhere in this disclosure, the phase angle FI, XI appears to exhibit a phase shift of approximately 180 degrees, when the operating point 550, 205 changes from below BEP to above BEP, or vice versa. Therefore, it would appear to be relevant to analyze a current phase angle parameter value FI, XI in terms of deviation from the reference direction, illustrated as zero (0) degrees and 360 degrees in figures 16, 17, 18 and 19A.

Thus, any phase angle parameter value FI, XI having a numerical value exceeding 180 degrees, may be translated into a phase deviation value FIDEV, wherein

FIDEV = FI - 360

Accordingly, when the phase angle parameter value FI, XI is 213,75 degrees (See column #03 of table 6 in conjunction with figure 16 and/or figure 19A), then the corresponding phase deviation value FIDEV is:

FIDEV = FI - 360 = 213,75 - 360= -146,25 degrees

Thus, referring to figure 19A in conjunction with col. #02 of table 6, the phase angle FI appears to be indicative of a current operating point in relation to a Best Efficiency Point. In other words, the phase angle <P(r) = FI(r) may exhibit a predetermined value when the pump operates at BEP flow condition. When the phase angle O(r) = FI(r) deviates from the predetermined value, that deviation appears to be indicative of operation away from BEP flow condition. In the example illustrated in figure 19A, the predetermined value was zero (0) degrees, so that the status indicator object 550BEP indicative of the pump operating at BEP flow condition exhibits a zero degree phase angle. Thus, the status indicator object relating to Best Efficiency Operation 550BEP = 550(p+4) may have a phase angle <b(r) = FI(r) = (p+4) = 0 degrees.

Accordingly, a deviation value indicative of a current operating point deviation from BEP can be obtained by:

Counting a total number of samples (NB - NO = NB - 0 = NB =1280) from the first reference signal occurrence in sample number No = 0 to the second reference signal occurrence in sample number NB=1280, and

Counting another number of samples (Np - No = Np -0 = Np) from the first reference signal occurrence at No = 0 to the occurrence of the peak amplitude value Sp at sample number Np, and generating said first temporal relation (XI, Rr(r); TD; FI(r)) based on said another number Np and said total number NB. This can be summarized as:

Xl(r) = FI(r)= R-r(r) = RT(760)= (NP - No ) / (NB - No) = (760 - 0) / (1280-0)

When the above relation is expressed as a phase angle FI:

FI(r) = 360 * 760/1280 = 213,75 degrees

Thus, information indicative of a momentary operating point XI, or identifying a momentary operating point XI, may be generated by:

Counting a total number of samples (NB) from the first reference signal occurrence to the second reference signal occurrence, and

Counting another number of samples (Np) from the first reference signal occurrence to the occurrence of the peak amplitude value Sp at sample number Np, and generating said first temporal relation (XI ; R-r(r); TD; FI(r)) based on a relation between said sample number Np and said total number of samples i.e. NB.

FIDEV ⁼ FI - 360

In this case, when

FIDEV = FI - 360 = 213,75 - 360= -146,25 degrees

This is illustrated in Figure 19A.

For clarity, Figure 19A also illustrates a phase angle parameter value FI(p+ 1 ) for the status indicator object 550(p+ 1 ) and the corresponding phase deviation value FIDEV(P+1 ).

Moreover, Figure 19A also illustrates a phase deviation value FlDEv(r-l) corresponding to the phase angle parameter value Fl(r-l) for the status indicator object 550(r- 1 ).

The relation generator 1050 may generate an update of relation value XI with a delivery frequency that depends on the rotational speed of the impeller 20. The delivery frequency may be adapted, dependent on processing capacity of the data processing device 350 (See e.g. figure 3). The status parameter extractor 450C may be configured to deliver an updated value FI(r), Xl(r) e.g. once per 100 revolutions. Alternatively, the updated value FI(r), Xl(r) may be delivered e.g. once per 10 revolutions.

Alternatively, the status parameter extractor 450C may be configured to deliver an updated value Xl(r) once per revolution. In this manner a delivered updated value Xl(r) may be based on L values generated during one revolution. The latest update, number r, of the first internal status parameter Xl(r) may be delivered on a first status parameter extractor output 1060.

With reference to Figure 23, the vibration event signature detector 990 may be configured to detect a peak amplitude sample value Sp. The vibration event signature detector 990 has an output 1070 for delivering a detected vibration signal amplitude peak value Sp. The detected vibration signal amplitude peak value Sp may be delivered from the output 1070 of vibration signal peak amplitude detector 990 to an output 1080 of status parameter extractor 450C. The output 1080 constitutes a second status parameter extractor output for delivery of a second internal status parameter X2(r), also referred to as Sp(r). The second internal status parameter X2(r) is delivered at the same delivery frequency as the first internal status parameter XI (r).

Moreover, the first internal status parameter Xl (r) and the second internal status parameter X2(r) are preferably delivered simultaneously, as a set of internal status parameter data (XI (r); X2(r)). In the notation Xl(r), the “r” is a sample number indicating a time slot, i.e. increasing number value of “r” indicates temporal progression, in the same manner as the number “i” in column #01 in table 3.

of fluid at several flow rates

A problem to be addressed by examples in this disclosure is how to improve the pumping process in a centrifugal pump. This problem is addressed by examples, such as a system including a pump 10 having an adaptive volute and a vibration sensor.

Another problem to be addressed by examples in this disclosure is how to improve the pumping process in a centrifugal pump during dynamic and variable fluid system conditions. This problem is addressed by examples, such as a system including a pump 10 having an adaptive volute and a vibration sensor and a method of operating such a system.

Figure 24 illustrates a pump 10 having an adaptive volute 75 A and a sensor 70, 70₇₇, 70₇₈.. By controlling the volume of the volute, by adjusting a cross sectional area of the volute based on vibration data from the sensor 70, 70?7, 7078, a best efficiency point of operation flow can be achieved while varying the rotational speed. Thus, a speed of operation fROT of the impeller 20 can be controlled based on required flow, while the cross sectional area of the adaptive volute is controlled based on at least one of the internal state parameters XI, X2, X3,..., Xm, disclosed herein, such as e.g. the parameter Xl(r), FI(r).

This solution advantageously enables the provision of a desired flow QOUT while maintaining the internal state of the pump at a Best Efficiency Point of operation, or substantially at a Best Efficiency Point of operation.

This solution also advantageously enables the provision of a laminar, or substantially laminar, desired flow through the pump while maintaining the internal state of the pump at a Best Efficiency Point of operation, or substantially at a Best Efficiency Point of operation during dynamic and variable fluid system conditions. This advantageously enables the delivery of fluid with a minimized, or eliminated, fluid pulsation. Moreover, this solution advantageously enables the delivery of fluid with a minimized, or eliminated, turbulent flow. Minimized, or eliminated, turbulent flow, is of value in a number of industries, such as e.g. in the dairy industry, wherein there is a need to transport fluids, such as milk products which may be adversely affected by turbulent flow.

The pump 10, 10A may operate and function as disclosed in WO 2021/055879, the content of which is hereby incorporated by reference.

The set-up as illustrated in Figure 24 may be used in combination with the example status parameter extractors 450, 450C as exemplified in this disclosure. With reference to Figure 15A and/or figure 15B, the set-up, as illustrated in Figure 24, may be used for generating the marker signal P(i) which is delivered to impeller speed value generator 500. Thus, the impeller speed value generator 500 will receive a marker signal P(i) having a position indicator signal value every 360/L degrees during a revolution of the impeller 20. Thus, the Fast Fourier Transformer 510 will receive a marker signal value P(j)=l , from the speed value generator 500, every 360/L degrees during a revolution of the impeller 20 when the rotational speed fROT is constant. Alternatively, the Fast Fourier Transformer 510 will receive a marker signal value P(q)=l, from the decimator 470, 470B, every 360/L degrees during a revolution of the impeller 20 when the rotational speed TROT varies. I l l

Moreover, the speed value generator 500 will be able to generate even more accurate speed values fRor(j) when it receives a marker signal P(i) having a position indicator signal value, e.g. P(i)= 1 , every 360/L degrees during a revolution of the impeller 20.

As for appropriate settings of the FFT 510 when it receives a marker signal value P(j)=l every 360/L degrees during a revolution of the impeller 20, this means that the fundamental frequency will be the repetition frequency fR.

Again, reference is made to the Fourier series (See Equation 6 below):

In this embodiment it is noted that the fundamental frequency will be one per vane 310 when the FFT 510 receives a marker signal value P(j)= 1 every 360/L degrees during a revolution of the impeller 20.

As noted above, the settings of the FFT 510 should be done with a consideration of the reference signal. As noted above, the position signal P(j), P(q) (see Figure 15A and/or figure 15B) may be used as a reference signal for the digital measurement signal S(j),S(q).

According to some embodiments, when the FFT analyzer is configured to receive a reference signal, i.e. the position signal P(j), P(q), Ps, Pc once every 360/L degrees during a revolution of the impeller 20 and L is the number of vanes 310 in the impeller 20, then the setting of the FFT analyzer may be set to fulfil the following criteria: The integer value Oi is set to unity, i.e. to equal 1, and the settable variables OMAX, and B_n are selected such that the mathematical expression

becomes a positive integer.

Differently expressed: When integer value Oi is set to equal 1, then settable variables OMAX and B_n should be set to integer values so as to render the variable NR a positive integer, wherein

Using the above setting , i.e. integer value Oi is set to equal unity, and with reference to Figure 15A and/or figure 15B and equation 6 above, the FFT 510 may deliver the amplitude value C_n for n=l , i.e. Ci = Sp(r). The FFT 510 may also deliver the phase angle for the fundamental frequency

Hence, according to embodiments of this disclosure, when the FFT 510 receives a reference signal, i.e. the position signal P(j), P(q), Ps, Pc, once every 360/L degrees during a revolution of the impeller 20 and L is the number of vanes 310 in the impeller 20, then the FFT analyzer may be configured to generate a phase angle value <I>L for a signal whose repetition frequency fR is the frequency of order L, wherein L is the number of vanes 310 in the rotating impeller 20.

With reference to Figure 15A and/or figure 15B in conjunction with figure 1 and equation 6 above, the status values Sp(r) = Ci and FI(r) = i may be delivered to the Human Computer Interface (HCI) 210 for providing a visual indication of the analysis result. As mentioned above, the analysis result displayed may include information indicative of an internal state of the centrifugal pump process for enabling the operator 230 to control the centrifugal pump. With reference to figures 16, 17, 18, 19A, and 19B, the example illustrations of visual indications of analysis results are valid for the set-up of the rotating pump impeller 20, as illustrated in Figure 24, whereby the FFT 510 will receive a marker signal P(i), P(j), P(q) having a position indicator signal value every 360/L degrees, wherein L is the number of vanes 310 in the impeller 20.

Whereas the above discussion in relation to settings of the FFT 510 refers to the Fourier series and equations 5 and 6 for the purpose of conveying an intuitive understanding of the background for the settings of an FFT transformer 510, it is noted that the use of digital signal processing may involve the discrete Fourier transform (See Equation 7 below):

Equation 7:

Thus, according to embodiments of this disclosure the above discrete Fourier transform (DFT) may be comprised in signal processing for generating data indicative of the internal state of a centrifugal pump, such as that discussed in connection with embodiments of the status parameter extractor 450. In this connection, reference is made to e.g. figures 3, 4, 5, 15 and/or 24. In view of the above discussion on the subject of FFT and the Fourier series, the discrete Fourier transform will not be discussed in further detail, as the skilled reader of this disclosure is well acquainted with it.

In summary, as regards appropriate settings of the FFT 510 and the above equations 5 and 6, it is noted that the phase angle for the n:th partial, i.e. <b_n, may be indicative of the information identifying a momentary operating point. In particular, the phase angle for the n:th partial, i.e. <b_n, may be indicative of the position of the detected event signature 205, expressed as a part of the distance between two adjacent vanes 310 in a rotating impeller 20. With reference to table 6 above and figure 14, the total distance between two adjacent vanes may be regarded as 360 degrees, and value of the phase angle for the n:th partial, i.e. n, divided by 360 may be indicative of a percentage of the total distance between the two adjacent vanes. This can be seen e.g. by comparing col. #2 in table 5 and table 6 above. As mentioned above, _n = phase angle for the n:th partial, and C_n = Amplitude for the n:th partial. As discussed above, considering the number L of vanes in the rotating impeller 20 and the number of reference signals being generated and, as a consequence thereof, the order Oi of a signal of interest, the FFT 510 may be set so as to deliver a phase angle for the n:th partial, _n, and an amplitude for the n:th partial, C_n, so that the phase angle for the n:th partial, i.e. _n, may be indicative of the information identifying a momentary operating point. Moreover, as noted above, the FFT 510 may be set so as to render the variable NR a positive integer, wherein

and wherein Oi is set to a integer value such as e.g. the number L of vanes 310, OMAX is set to an integer value,

B_n is set to a integer value.

With reference to Figure 24, an example system 700 includes a centrifugal pump 10, 10A having an adaptive volute 75A and a sensor 70, 70?7, 70₇₈.

Adaptive volutes 75A of the present disclosure can include one or more mechanisms to adjust a cross-sectional area of the volute such that the volute can maintain near uniform static pressure, i.e., best efficiency operation (BEP), around a periphery of the impeller disposed within the casing 62 of the pump 10 (See also discussion related to figures 14A and 14D). For example, the volute cross-sectional area can be expanded or contracted to shift the BEP of the pump based on one or more operating parameters of the pump and/or fluid system to maintain a higher operating efficiency across a varying range of conditions. The one or more operating parameters can include the one or more of the internal state parameters disclosed in this disclosure, such as the internal state parameters XI, X2, X3,..., Xm, where the index m is a positive integer, as discussed e.g. in connection with figure 2C.

Thus, for example, the volute area can be expanded or contracted to shift the operating point of the pump based on the first parameter value, i.e. the first polar angle Xl(r), FI(r), (r), TD, TDI .

Alternatively, the volute area can be expanded or contracted to shift the operating point of the pump based on the second parameter value, i.e. the detected amplitude value X2(r) Sp(r), Spi which is indicative of an amplitude of detected fluid pressure pulsation PFP. According to another example, the volute area can be expanded or contracted to shift the BEP of the pump based on

- the first parameter value, i.e. the first polar angle XI (r), and based on

- the second parameter value, i.e. the detected amplitude value X2(r) Sp(r).

The adaptive centrifugal pump 10A of figure 24 has an impeller 20 that, during operation, rotates at a speed of rotation f_ROT, driven by a shaft 710. The shaft is caused to rotate by a drive motor 715. The shaft 710 may be connected to the drive motor 715 via a gear box 716. Referring to figure 24, a sensor 70, 70?7, 7078 may be mounted on the casing 62 for generating a vibration signal SEA, SMD, Se(i), S(j), S(q) dependent on fluid material pressure pulsation PFP in the pump. The vibration sensor 70, 7O77, 70?8 may include one or more of the sensors as disclosed in connection with figure 2A.

The pump 10A may also be also provided with a position sensor 170 for generating a position signal EP, PS, P(i), P(j), P(q) indicative of a rotational position of said impeller 20 in relation to the casing 62. As shown in Figure 24, a position marker device 180 may be provided in association with the impeller 20 such that, when the impeller 20 rotates around the axis of rotation 60, the position marker 180 passes by the position sensor 170 once per revolution of the impeller, thereby causing the position sensor 170 to generate a revolution marker signal value PS. The position marker 180 is illustrated, in figure 24, as being attached to the shaft 710, but that is only an example. The position signal EP, PS, P(i), P(j), P(q) may be generated in a manner as disclosed anywhere else in this disclosure (See for example the disclosure of alternative position sensors 170 and position markers 180 in connection with figure 2A).

As mentioned above, the centrifugal pump 10A of figure 24 has an adaptive volute 75A. With reference to figure 24, the example pump 10A comprises a casing 62 A having a movable volute boundary wall 720. The volute boundary wall 720 may be movable in a direction parallel to the axis of rotation 60.

The movable volute boundary wall 720 may be formed as a plane which is perpendicular to the direction of the axis of rotation 60. The movable volute boundary wall 720 is curved, and it has an inner radius that may correspond to the radius RMIC of the impeller 20 (See figure 24 and figure 14D part II). The outer radius of the movable volute boundary wall 720 exhibits a gradually widening radius so as to fit the spiral casing 62A of the pump.

The movable volute boundary wall 720 may be coupled to an actuator 725 configured to cause movement 727 of the movable volute boundary wall 720 in response to a Volume set point signal VPSP , U2sp. Accordingly, the actuator may be configured to cause movement 727E of the movable volute boundary wall 720 in a direction 727E that causes the volute cross- sectional area to be expanded in response to the Volume set point signal VPSP , U2SP providing an “Expand value”. Conversely, the actuator may be configured to cause movement 727C of the movable volute boundary wall 720 in a direction 1 1C that causes the volute cross- sectional area to be contracted, i.e. smaller, in response to the Volume set point signal Vpsp , U2SP providing a “Reduce value”. Thus, the volume of the volute 75A may be adjusted, thereby enabling a controlled variable flow QOUT from the pump outlet 66 at a certain impeller rotational speed f_ROT (See figure 24 in conjunction with any of figures 2A, 2D, 2E, 14A to 14G.

By controlling the volume of the volute, by adjusting a cross sectional area of the volute based on vibration data from the sensor 70, 70₇₇, 70₇₈, a best efficiency point of operation flow can be achieved while varying the rotational speed f_ROT- Thus, a speed of operation FROT of the impeller 20 can be controlled based on required flow, while the cross sectional area of the adaptive volute is controlled based on at least one of the internal state parameters XI, X2, X3,..., Xm, disclosed herein, such as e.g. the parameter XI (r), FI(r).

This solution advantageously enables the provision of a desired flow QOUT while maintaining the internal state of the pump at a desired operating point in relation to BEP, such as e.g. at a Best Efficiency Point of operation, or substantially at a Best Efficiency Point of operation.

Referring to figure 24, a centrifugal pump controller 240 may be configured to deliver an impeller speed set point value Ulsp, fROTSP so as to control the rotational speed f_ROT of the impeller 20. According to some embodiments, the set point value Ulsp, fROTSP is set by the operator 230.

The centrifugal pump controller 240 may also be configured to deliver the Volume set point signal Vpsp , U2SP, as discussed above, so as to control the outlet fluid volume per impeller revolution. According to some embodiments, the set point value U2SP, VPSP , is set by the operator 230.

In order to assist the operator 230, the control room may include the HCI 210, 210S (See also figures 1 A and/or IB) which is coupled to the analysis apparatus 150, or monitoring module 150 A, configured to provide information indicative of an internal state X of the centrifugal pump 10. The HCI 210 may include a display 210S, and it may be configured to convey information as disclosed in connection with one or more of figures 16, 17, 18, 19 A, 19B, 19C, 19D,19E, and/or 19F. Accordingly, the system 700 provides an improved user interface 210, 210S, 250 that enables an operator 230, to control the pump 10A so as to improve the pumping process in the centrifugal pump 10A.

Figure 25A shows another example system 700R including a pump 10A, 10AR having an adaptive volute 75 AR and a sensor 70, 70₇₇, 70₇₈. In figure 25 A the pump 10AR is shown in a sectional side view, i.e. a view in which the axis of rotation 60 of the impeller is parallel to the plane of the paper.

Figure 25B is a sectional top view of the pump 10A_R shown in figure 25A.

The system 700R illustrated in figures 25A and 25B may include the features of the system 700 disclosed and described above in connection with figure 24, but in the example system 700R the example pump 1 OAR it is the radially outer boundary wall 732 of the adaptive volute that is movable.

As mentioned above, the centrifugal pump 10AR of figure 25 has an adaptive volute 75AR. With reference to figure 25A, the example pump 10AR comprises a casing 62AR having a movable volute boundary wall 732. The movable volute boundary wall 732 may be movable in a direction perpendicular to the axis of rotation 60 of the impeller 20. The movable volute boundary wall 732 may be formed as movable spiral 732. In this manner the movable spiral wall 732 provides an adjustable gradual widening of the adaptive volute 75AR.

The movable volute boundary wall 732R may be coupled to an actuator 725R configured to cause radial movement 727 of the movable volute boundary wall 732R in response to a Volume set point signal VPSP , U2SP. Accordingly, the actuator 725R may be configured to cause movement 727E of the movable volute boundary wall 732R in a direction 727E that causes the volute cross-sectional area to be expanded in response to the Volume set point signal VPSP , U2SP providing an “Expand value”. Conversely, the actuator may be configured to cause movement 1 1Q of the movable volute boundary wall 720 in a direction 727C that causes the volute cross-sectional area to be contracted, i.e. smaller, in response to the Volume set point signal VPSP , U2SP providing a “Reduce value”. Thus, the volume of the volute 75AR may be adjusted, thereby enabling a controlled variable flow QOUT from the pump outlet 66 at a certain impeller rotational speed FROT (See figure 25A and/or 25B in conjunction with any of figures 2A, 2D, 2E, 14A to 14G.

By controlling the volume of the volute, by adjusting a cross sectional area of the volute based on vibration data from the sensor 70, 70₇₇, 70₇₈,. a best efficiency point of operation flow can be achieved while varying the rotational speed (ROT. Thus, a speed of operation TROT of the impeller 20 can be controlled based on required flow, while the cross sectional area of the adaptive volute is controlled based on at least one of the internal state parameters XI, X2, X3,..., Xm, disclosed herein, such as e.g. the parameter XI (r), FI(r).

With reference to figure 24 and figures 25A and 25B, when the operator desires to increase the flow QOUT from the pump 10 the operator may adjust the impeller speed of rotation set point value fROTSP to a higher value until the desired flow QOUT from the pump 10 is obtained. Conversely, when the operator desires to decrease the flow QOUT from the pump 10 the operator may adjust the impeller speed of rotation set point value FROTSP to a lower value until the desired flow QOUT from the pump 10 is obtained.

This solution advantageously enables the provision of a desired flow QOUT while maintaining the internal state of the pump at a desired operating point in relation to the Best Efficiency Point of operation (BEP). When it is desired to operate the pump at a Best Efficiency Point of operation, or substantially at a Best Efficiency Point of operation, the operator may adjust the Volume set point signal value VPSP , U2SP to a value that renders the parameter XI, FI to adopt the reference value corresponding to the Best Efficiency Point of operation. The numerical FI value corresponding to the Best Efficiency Point of operation for an individual pump may depend on the physical locations of the sensors 180 and 70 on the pump 10, 10A, 10AR.

Whereas figures 24 and 25A and 25B illustrate different configurations providing a pump with an adaptive volute 75A, 75AR it is to be noted that the present disclosure is not limited to the pump configurations illustrated. The pump 10, 10A may be configured and function as disclosed in WO 2021/055879, the content of which is hereby incorporated by reference. One skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. Figure 26 shows a somewhat diagrammatic and schematic view of yet another embodiment of a system 730 including a pump 10A, I OAR having an adaptive volute 75 A, 75 AR and a sensor 70, 70₇₇, 70₇₈.. In figure 25A the pump 10A is shown in a sectional side view, i.e. a view in which the axis of rotation 60 of the impeller is parallel to the plane of the paper.

The system 730 of figure 26 may include parts, and be configured, as described in any of the other embodiments described in this disclosure, e.g. in relation to figures 1-25. In particular, the apparatus 150, 150A, shown in figure 26 may be configured as described in any of the other embodiments described in this disclosure, e.g. in relation to figures 1-25.

However, in the embodiment of the system 730 illustrated in figure 26, the apparatus 150 includes a monitoring module 150A as well as a control module 150B. Although the drawing illustrates the apparatus 150 as two boxes, it is to be understood that the apparatus 150 may well be provided as a single entity 150 including a monitoring module 150A as well as a control module 150B, as indicated by the unifying reference 150.

The system 730 is configured to control an internal state of in a pump 10A, I OAR having an adaptive volute 75A, 75AR and a sensor 70, 70₇₇, 70₇₈..

The system 730 may comprise a device 170, 180 for generating a position signal relating to a rotational position of the impeller 20 in the pump 10A 1 OAR. The device 170, 180 may include the position sensor 170 and the marker 180 as described elsewhere in this disclosure, for generating a time sequence of position signal sample values P(i), P(j), P(q).

A sensor 70, 7O77, 70?8 is provided and it is configured to generate a vibration signal SEA, SMD, Se(i), S(j), S(q) dependent on fluid material pressure pulsations PFP. The vibration signal SEA, Se(i), S(j), S(q) may include a time sequence of vibration sample values Se(i), S(j), S(q).

The apparatus 150 of the system 730 may comprise a monitoring module 150A and a control module 150B. The monitoring module 150A comprises a status parameter extractor 450, 450C configured to detect a first occurrence of a first reference position signal value in said time sequence of position signal sample values P(i), P(j), P(q) (See tables 2, 3 and 4 above, wherein column #2 illustrates the position signal having values 1; 1C).

The status parameter extractor 450 may be configured to detect a second occurrence of a second reference position signal value 1 ; 1C; 360 degrees; in said time sequence of position signal sample values P(i), P(j), P(q)). The status parameter extractor 450, 450C may also be configured to detect an occurrence of an event signature Sp(r); Sp in said time sequence of vibration sample values Se(i), S(j), S(q).

The status parameter extractor 450 may be configured to generate data indicative of a first temporal relation FI(r), Xl(r) between the event signature occurrence, and the first and second occurrences.

As mentioned above, the system 730 includes a control module 150B configured to receive data indicative of an internal state of the pump 10A, 10AR from the monitoring module 150, 150A. The data indicative of an internal state can include any of the information generated or delivered by the status parameter extractor 450, as described above in relation to any of the figures 1-25 in this disclosure. With reference to figure 26, the control module 150B includes a regulator 755 for controlling an adaptive volute (75A) based on an operating point reference value FIREFW (See fig 26), said first temporal relation FI(r); Xl(r) (See figs 1 -25), and an operating point error value FlERR(r) (see fig 26).

The operating point error value (FlERR(r) ) depends on said operating point reference value FIREFW, and said first temporal relation Ri-(r); TD; FI(r) (See figs 3 -26). The operating point reference value FIREFW may he generated by manual input (not shown in Fig 26, but it may alternatively be done as discussed e.g. in connection with figure 1 A and/or figure IB above.

As shown in figure 26, the said operating point error value (FIERRW ) ^may depend on a difference between said operating point reference value FIREFW ), and the first temporal relation R_T(r); T_D; FI(r); Xl(r).

The regulator 755 may be configured to control an operating parameter, such as speed of rotation of impeller and/or cross-sectional area of an adaptive volute in dependence on the operating point reference value FIREFW- The status parameter extractor 450 may be configured to generate said first temporal relation R-r(r); TD; FI(r); Xl(r) as a phase angle (FI(r).

The regulator 755 may be configured to include a proportional-integral-derivative controller (PID controller). Alternatively, the regulator 755 may be configured to include a proportionalintegral controller (PI controller). Alternatively, the regulator 755 may be configured to include a proportional controller (P controller).

Alternatively, the regulator 755 may be configured to include Kalman filtering, also known as linear quadratic estimation (LQE). Kalman filtering is an algorithm that uses a series of measurements observed over time, including statistical noise and other inaccuracies, and produces estimates of unknown variables that tend to be more accurate than those based on a single measurement alone, by estimating a joint probability distribution over the variables for each timeframe.

Figure 27 shows a schematic block diagram of a distributed process monitoring system 770. Reference numeral 780 relates to a client location with a pump 10 having an impeller 20, as discussed above in relation to preceding drawings in this document. The client location 780, which may also be referred to as client part or pump location 780, may for example be the premises of a mining company, or e.g. a manufacturing plant for the manufacture of cement.

The distributed process monitoring system 770 is operative when one sensor 70 is, or several sensors 70, 70?7, 70₇₈ are, attached on or at measuring points on the pump.

The measuring signals SEA and Ep (See e.g. Figs. 1, 27, 26, 25) may be coupled to input ports of a pump location communications device 790. The pump location communications device 790 may include an Analogue-to-Digital converter 795 for A/D-conversion of the measuring signals SEA, and Ep. The A/D converter 975 may operate as disclosed in relation to A/D converter 330 elsewhere in this document, e.g. in connection with figure 3 and 5. The pump location communications device 790 has a communication port 800 for bi-directional data exchange. The communication port 800 is connectable to a communications network 810, e.g. via a data interface 820, for enabling delivery of digital data corresponding to the measuring signals SEA, and Ep. The communications network 810 may be the world wide internet, also known as the Internet. The communications network 810 may also comprise a public switched telephone network.

A server computer 830 is connected to the communications network 810. The server 830 may comprise a database 840, user input/output interfaces 850 and data processing hardware 852, and a communications port 855. The server computer 830 is located on a server location 860, which is geographically separate from the pump location 780. The server location 860 may be in a first city, such as the Swedish capital Stockholm, and the pump location 780 may be on the countryside near a pump, and/or in another country such as for example in Norway, Australia or in the USA. Alternatively, the server location 860 may be in a first part of a county and the pump location 780 may be in another part of the same county. The server location 860 may also be referred to as supplier part 860, or supplier location 860.

According to an example a central control location 870 comprises a monitoring computer 880 having data processing hardware and software for monitoring and/or controlling an internal state of a pump 10 at a remote pump location 780. The monitoring computer 880 may also be referred to as a control computer 880. The control computer 880 may comprise a database 890, user input/output interfaces 900 and data processing hardware 910, and a communications port 920, 920A, or several communications ports 920, 920A, 920B. The central control location 870 may be separated from the pump location 780 by a geographic distance. The central control location 870 may be in a first city, such as the Swedish capital Stockholm, and the pump location 780 may be on the countryside near a pump, and/or in another country such as for example in Norway, Australia or in the USA. Alternatively, the central control location 870 may be in a first part of a county and the pump location 780 may be in another part of the same county. By means of communications port 920, 920A the control computer 880 can be coupled to communicate with the pump location communications device 790. Hence, the control computer 880 can receive the measuring signals SEA, and Ep (See e.g. Figs. 1, 27, 26, 25) from the pump location communications device 790 via the communications network 810.

The system 770 may be configured to enable the reception of measuring signals SEA, and Ep in real time, or substantially in real time or enabling real time monitoring and/or real time control of the pump 10 from the location 870. Moreover, the control computer 880 may include a monitoring module 150, 150A as disclosed in any of the examples in this document, e.g. as disclosed in connection with any of the drawings 1-26 above.

A supplier company may occupy the server location 860. The supplier company may sell and deliver apparatuses 150 and/or monitoring modules 150A and/or software for use in an such apparatuses 150 and/or monitoring modules 150A. Hence, supplier company may sell and deliver software for use in the control computer 880 at the central control location 870. Such software 370, 390, 400 is discussed e.g. in connection with Figure 4. Such software 370, 390, 400 may be delivered by transmission over said communications network 810. Alternatively such software 370, 390, 400 may be delivered as a computer readable medium 360 for storing program code. Thus the computer program 370, 390, 400 may be provided as an article of manufacture comprising a computer storage medium having a computer program encoded therein.

According to an example embodiment of the system 770 the monitoring computer 880 may substantially continuously receive measurement signals measuring signals SEA, and Ep (See e.g. Figs. 1, 27, 26, 25) from the pump location communications device 790, e.g. via the communications network 810, so as to enable continuous or substantially continuous monitoring of the internal state of the pump 10. The user input/output interfaces 900 at the central control location 870 may comprise a screen 900S for displaying images and data as discussed in connection with HCI 210 elsewhere in this document. Thus, user input/output interfaces 900 may include a display, or screen, 900S, 210S for providing a visual indication of an analysis result. The analysis result displayed may include information indicative of an internal state of the pump process for enabling an operator 930 at the central control location 870 to control the pump 10.

Moreover, the monitoring computer 880 at the central control location 870 may be configured to deliver information indicative of an internal state of the pump process to the HCI 210, via the communications port 920, 920B and via the communications network 810. In this manner, the monitoring computer 880 at the central control location 870 may be configured to enable an operator 230 at the client location 780 to control the pump. The local operator 230 at the client location 780 may be placed in the control room 220 (See figure 1A and/or figure IB and/or Figure 27). Thus, the client location 780, 220 may include a second pump location communications device 790B. The second pump location communications device 790B has a communication port 800B for bi-directional data exchange, and the communication port 800B is connectable to the communications network 810, e.g. via a data interface 820B.

Although it has, for the purpose of clarity, been described as two location communications devices 790, 790B, there may, alternatively, be provided a single pump location communications device 790, 790B, and/or a single communications port 800, 800B for bidirectional data exchange. Thus, the items 790 and 790B may be integrated as one unit at the pump location 780, and likewise, the items 820 and 820B may be integrated as one unit at the pump location 780.

Figure 28 shows a schematic block diagram of yet another embodiment of a distributed process monitoring system 940. Reference numeral 780 relates to a pump location with a pump 10 having an impeller 20, as discussed above in relation to preceding drawings in this document. The distributed process monitoring system 940 of figure 28 may include parts, and be configured, as described in any of the other embodiments described in this disclosure, e.g. in relation to figures 1-28. In particular, the monitoring apparatus 150, also referred to as monitoring module 150A, shown in figure 28 may be configured as described in any of the other embodiments described in this disclosure, e.g. in relation to figures 1-28. In particular, the process monitoring system 940 illustrated in figure 28, may be configured to include a monitoring module 150A, as disclosed in connection with figure 27, but located at the central control location 870.

Moreover, in the process monitoring system 940 illustrated in figure 28, the pump location 780 includes a control module 150B, as described above e.g. in connection with figure 26.

Thus, the internal state of the pump 10 may be automatically controlled by control module 150B located at or near the pump location 780, whereas the monitoring computer 880 at the central control location 870 may be configured to deliver information indicative of an internal state of the pump process to the HCI 900, 900S for enabling an operator 930 at the central control location 870 to monitor the internal state of the pump 10.

The measuring signals SEA, SEA77, SEA78, and Ep (See e.g. Figs. 1, 27, 26, 25) may be coupled to input ports of the pump location communications device 790. The pump location communications device 790 may include an Analogue-to-Digital converter 795 for A/D-conversion of the measuring signals SEA, SE ?7, SEA78, and Ep. The A/D converter 975 may operate as disclosed in relation to A/D converter 330 elsewhere in this document, e.g. in connection with figure 3 and 5. The pump location communications device 790 has a communication port 800 for bi-directional data exchange. The communication port 800 is connectable to the communications network 810, e.g. via a data interface 820. The communication port 800 is connectable to a communications network 810, e.g. via a data interface 820, for enabling delivery of digital data corresponding to the measuring signals SEA, SEA77, SEA78, and Ep.

Moreover, the client location 780 may include a second pump location communications device 790B. The second pump location communications device 790B has a communication port 800B for bi-directional data exchange, and the communication port 800B is connectable to the communications network 810, e.g. via a data interface 820B so as to enable reception, by the control module 150B, of data indicative of an internal state of the pump 10.

As illustrated in Figure 28, data indicative of an internal state of the pump 10 may be generated by the monitoring module 150A at the central location 870.

Although figure 28, for the purpose of clarity, describes two location communications devices 790, 790B, there may, alternatively, be provided a single pump location communications device 790, 790B, and/or a single communications port 800, 800B for bi-directional data exchange. Thus, the items 790 and 790B may be integrated as one unit at the pump location 780, and likewise, the items 820 and 820B may be integrated as one unit at the pump location 780.

Figure 29 shows a schematic block diagram of yet another embodiment of a distributed process control system 950. Again, reference numeral 780 relates to a pump location with a pump 10 having an impeller 20, as discussed above in relation to preceding drawings in this document. The distributed process monitoring system 950 of figure 29 may include parts, and be configured, as described in any of the other embodiments described in this disclosure, e.g. in relation to figures 1-28. In particular, the monitoring apparatus 150, also referred to as monitoring module 150A, shown in figures 28 and 29 may be configured as described in any of the other embodiments described in this disclosure, e.g. as discussed in relation to figures 1- 28. Moreover, the process monitoring system 950 illustrated in figure 29, may be configured to include a control module 150B, as described above e.g. in connection with figure 26 as well as a monitoring module 150A, as disclosed in connection with figure 27.

In the example of figure 29, the monitoring module 150A and the control module 150B are provided at the control location 870. The control location 870 may be remote from the pump location 780. Communication of data between the control location 870 and the pump location 780 may be provided via data ports 820 and 920 and the communications network 810, as discussed above in connection with preceding figures.

Figure 30A illustrates yet an interpretation of a repetitive flow pattern in a centrifugal pump 10 when the pump operates at a flow lower than BEP flow. Figures 30B and 30C in conjunction with figure 30A illustrate an advantageous positioning of the vibration sensor 70, and a discussion that is believed to explain why that sensor positioning is advantageous.

As noted elsewhere in this disclosure, when the pump operates at a flow lower than BEP flow, the static pressure P?s in the wider volute part 78 is higher than the static pressure P77 in the narrower volute part 77:

P78 > P77

Figure 30A part I illustrates a rotational position of the impeller 20 wherein the vane tip 310A is just passing by the tongue 65. Here, vane tip 310A is at its closest position to the tongue 65, so that the vane tip 310A substantially closes the passage opening between narrow volute portion 77 and the broad volute portion 78. The vane 310A is followed by an adjacent vane 310B. Thus, Figure 30A part I corresponds to Figure 14B part I and 14E part I.

Figure 30B illustrates the tongue 65, the axis of impeller rotation 60, and a line 923 from the tip of tongue 65 and the axis of impeller rotation 60. A force F955 appears to be directed perpendicular to, or substantially perpendicular to, the line 923 and that force pulsates and it is repetitive at vane pass frequency X4. The vane pass frequency X4 is also discussed elsewhere in this disclosure. With reference to figures 30A, 30B and 30C an advantageous vibration sensor positioning is disclosed and discussed. Referring to Figure 30A part II and figure 14B part II, there is a pulsating leak flow q3’, during operation at a duty point flow below BEP-flow. This leak flow is believed to be caused by the pressure difference between the higher static pressure P78 in the wide portion 78 of the volute and the lower static pressure P77 in the narrow portion 78 of the volute, when the pump operates at a flow lower than BEP flow. As discussed in connection with figure 14E, there appears to be a local high pressure region at a leading edge of a vane tip, indicated by “+”, during most of its path in the volute, and a local low pressure region at a trailing edge of a vane tip, indicated by in parts I and II of figure 30A. With reference to figure 30A parts II and III it is believed that as a vane (See vane tip 30B) comes closer to the tip of the tongue 65 the speed v3’ of the fluid flow q3’ reaches a high amplitude. In fact, it would appear to have similarities with a draught, as indicated by the arrow V3’, in figure 30A part III, indicating the velocity V3’ of the pulsating flow passing the tip of the tongue 65. When the fluid speed V3’ near the tongue 65 is higher than the tangential speed V75T of the vane tip 31 OB (compare figure 14E where the tangential speed V75T is illustrated), the local pressures around the vane tip near the tongue appear to become reversed (See vane 31 OB in fig 30A part III), as indicated by “+” at the trailing side and

at the leading side of vane tip 31 OB. Thus, the fluid speed V3’ of the leakage flow q3’ between the tongue 65 and the tip of vane 31 OB is believed to momentarily reach a speed V3’ higher than the tangential speed V75T of the tip of vane 310B when the impeller is in a position between the position shown in figure 30A part II and the position shown in figure 30A part III. Accordingly, when the tip of vane 310B approaches the tongue 65, as shown in figure 30A part III, the vane 310B momentarily blocks, or substantially blocks, the leakage flow q3’ causing a sudden retardation, i.e. negative acceleration, of the fluid speed V3’.

This sudden retardation is believed to cause a change of pressure between leading side and trailing side of the vane 310 at, or near, the tongue position 65. Thus, the sudden retardation of the fluid speed V3’ is believed to cause a significant force F955, which may appear as a repetitive vibration. This pulsating force F955 is directed in the direction indicated by arrow V3’ in figure 30A part III during flow below BEP flow conditions, and the direction of this pulsating force is also indicated by arrow 955 in figure 30B.

Conversely, during flow above BEP flow conditions, the pulsating force F955 is directed in a direction -V3’, which is opposite to the direction indicated by arrow V3’ in figure 30 A part III (See also figure 30B). Thus in both cases, i.e. in case of flow above BEP and in case of flow below BEP, the pulsating force is in a direction 955 perpendicular to, or substantially perpendicular to, a line 923 from the tip of tongue 65 and the axis of impeller rotation 60 (see figure 30B).

Figure 30C is a sectional side view, section B-B of the pump 10 as shown in figure 30B. Thus, Figure 30C is a sectional side view, as seen in the direction of arrow 927 in figure 30B.

Thus, each vane 310 experiencing the above described pulsating force, which is due to sudden pressure changes, appears to cause repetitive vibration which may be detected by a vibration sensor 70, 7O925 positioned on or near a bearing 925 enclosing the shaft 710 (See fig 30C). Thus, the vibration sensor 70, 7O925 positioned on a bearing 925 may be configured to detect vibrations directed in the direction of arrow 955, i.e. perpendicular to, or substantially perpendicular to, a line 923 from the tip of tongue 65 and the axis of impeller rotation 60 (see figure 30B). Since the vanes are part of the impeller which is attached to the shaft 710 (See fig 30C), the pulsating force F955 appears to cause a repetitive vibration that affects the shaft 710. Experiments with various placements of vibration sensor 70 have indicated that when the vibration sensor 70 is positioned and configured to be particularly sensitive to vibrations that occur in the direction of arrow 955, i.e. perpendicular to, or substantially perpendicular to, a line 923 from the tip of tongue 65 and the axis 60 of impeller rotation (see figure 30B), then the detected vibration signal appears to be particularly clear. The discussion in relation to figures 30A, 30B and 30C about pulsating fluid speed V3’ and force F955 is believed to provide an explanation for why the detected vibration signal appears to be particularly clear when the sensor 70 is positioned and configured to detect vibrations that occur in the direction of arrow 955.

In this connection the vibration sensor 70, 70₉₂₅ may advantageously be configured to be attached on the bearing 925 of the pump shaft 710 for detecting vibrations having a direction movement perpendicular to, or substantially perpendicular to, a line 923 between the tip of tongue 65 and the axis of impeller rotation 60 (see figure 30B in conjunction with figure 30C). Alternatively, the vibration sensor 70, 70₇₈ may advantageously be configured to be attached on the casing 62, wherein the vibration sensor 70, 70₉₅₅, 70₇₈ is configured for high sensitivity for detecting vibrations having a direction 955 of movement perpendicular to, or substantially perpendicular to, a line 923 between the tip of tongue 65 and the axis of impeller rotation 60 (see figure 30C in conjunction with figure 30B).

Thus, the inventor concluded that it is advantageous to use, as measurement sensor 70, a vibration sensor positioned and configured for detecting vibrations having a direction 955 of movement perpendicular to, or substantially perpendicular to, a straight line 923 between the tip of the volute tongue 65 and an axis 60 of impeller rotation; wherein the vibration sensor 70, 70925, 7O955 is firmly attachable on a bearing (925) of a pump shaft (710), or said vibration sensor 70, 70₇₇, 7078, 70955 is firmly attachable on an outer surface of the pump casing (62).

Figure 31 is another example of a block diagram illustrating a centrifugal pump as a box 10B receiving a number of inputs Ul, ... Uk, and generating a number of outputs Yl, ... Yn. With reference to figure 31 it is noted that, for the purpose of analysis, a centrifugal pump 10 may be regarded as a black box 10B having a number of input variables, referred to as input parameters Ul, U2, U3, ... Uk, where the index k is a positive integer. In the example of figure 31, four input parameters U 1 , U2, U3, U4 are illustrated. Thus, figure 31 can be regarded as an embodiment of the block diagram of figure 2C. In this connection, it is noted that it may not be necessary to measure all input parameters.

Figure 31 is provided in order to illustrate an understanding of a relation between a pump 10 coupled to a fluid system 52, as illustrated in figure 34, on the one hand and on the other hand the characteristics of pump and fluid system, as illustrated in figure 2B. The fluid system 52, also referred to as piping system 52 may include a pipe for transporting fluid from the pump 10 to a fluid material consumer 50. According to an example, the fluid material consumer 50 is a tank for receiving fluid 30. According to another example the fluid material consumer 50 includes a headbox 50A, also referred to as head tank, whose purpose is to maintain a constant head on fiber slurry 30 to be delivered to a nozzle for ejecting fiber slurry, also referred to as pulp. During operation of the centrifugal pump 10B, the pump 10B has an internal state X, and it produces a number of output variables, also referred to as output system parameters Yl , Y2, Y3, ... Yn, where the index n is a positive integer.

The internal state X of the pump may be described, or indicated, by a number of internal state parameters XI, X2, X3,..., Xm, where the index m is a positive integer.

Referring to figure 31 in conjunction with figure 2B, the pump curve 207 indicates how the pump pressure Yl will change with flow Y2. In a fluid system 52, 40, 50 that fluctuates in pressure and flow over time, the system curve 209 changes over the lifetime and operation of the system 52. In this context, it is noted that operating parameters of the pump, such as the rotational speed Ul, f_ROT (See e.g. Figures 25 A and 26) may affect system parameters such as the pressure Yl and/or the flow Y2 (See figure 31 in conjunction with figure 2B)

When the pressure Yl is the fluid pressure at or near the outlet 66, also referred to as P54 (See e.g. figure 2A), then the system back pressure U3 may be equal to the pressure Yl :

U3 = Y1 = P54

Likewise, the input parameter U4 may be equal to the flow Y2 from the outlet 66, also referred to as QOUT (See e.g. figure 2A):

U4 = Y2 = QOUT

For the purpose of analysis, this can be illustrated as shown in figure 31, wherein a system back pressure Yl is illustrated as an input parameter U3 that affects the internal state X, and/or operating point 205, of the pump 10, 10B. Likewise, the flow Y2 from the outlet 66, also referred to as QOUT (See e.g. figure 2A), can be regarded as an input parameter U4 that affects the internal state X, and/or operating point 205, of the pump 10, 10B.

Accordingly, the internal state X, and thus the current operating point 205, 550, of the pump 10 depends on the pressure Yl and on the flow Y2. Thus, during operation of the pump 10, the internal state X(r) depends on at least some of the system parameters Yl, Y2, Y3, ... Yn.

The system back pressure U3 depends on the pressure Yl of the system 52 (See figure 31 in conjunction with figure 2B). Likewise, the input parameter U4 may relate to a pump flow U4 that depends on a flow Y2 in the system 52 (See figure 31 in conjunction with figure 2B). Referring to figure 31 and to the discussion in connection with figure 2C, it is noted that the internal state X of the pump 1 OB depends on the input vector U, and the output vector Y depends on the internal state vector X.

Thus, during operation of the pump 10, the internal state X can be regarded as a function of the input U :

X = fi(U ), wherein

Likewise, the state Y of the fluid system 52 can be regarded as an output Y of the black box 10B, wherein the output state Y is a function of the internal state X:

Y = f₂(X)

Figure 32 is a block diagram of the system including a centrifugal pump illustrated as a box 10 receiving a number of inputs Ul, ... Uk, and generating a number of outputs Yl, ... Yn. With reference to figure 31 and figure 32 it is noted that, for the purpose of analysis, a centrifugal pump 10 may be regarded as a black box 10B having a number of input variables, referred to as input parameters Ul, U2, U3, ... Uk, where the index k is a positive integer. During operation of the centrifugal pump 10, 10B, the centrifugal pump has an internal state X, and for the purpose of analysis, the centrifugal pump 10 may be regarded as the black box 10B having a number of output variables, also referred to as output system parameters Yl, Y2, Y3, ... Yn, where the index n is a positive integer.

Using the terminology of linear algebra, the input variables Ul, U2, U3,... Uk may be collectively referred to as an input vector U. Thus, the dimension of input vector U is k:

Input vector U: Dim (U) = k

Likewise, the internal state parameters XI, X2, X3,..., Xm may be collectively referred to as an internal state vector X.

The dimension of internal state vector X is m: Internal state vector X: Dim (X) = m

The system parameters Yl, Y2, Y3, ... Yn may be collectively referred to as an output vector Y.

The dimension of output vector Y is n:

Output vector Y : Dim (Y) = n

The internal state X of the pump 10, at a point in time termed r, can be referred to as X(r).

That internal state X(r) can be described, or indicated, by a number of internal state parameters XI, X2, X3,..., Xm, as discussed above. These internal state parameters define different aspects of the internal state X(r) of the pump 10 at time r.

The internal state X(r) of the centrifugal pump 10 depends on the input vector U(r).

It is an object of an aspect of this document to address the problem of how to maintain the internal pumping process of the pump 10 at a suitable operating point during operation of the pump. Thus, during operation of the pump 10 it may be desirable to counteract deviations from such a suitable operating point.

According to an aspect of this disclosure, this problem may be addressed by providing a model of the pumping process at an operating point. When regarding the above functions fi and f2, respectively, at operating points near a suitable operating point, the functions may be linear. Accordingly, at a selected operating point, the internal state X(r) can be regarded as a function of an earlier internal state X(r-l) and of the input U(r) in accordance with a linear model which may be written as follows:

X(r) = A * X(r-l) + B * U(r), (eq. 8.1) wherein A and B are coefficient matrices.

In this connection it is noted that in linear algebra, a coefficient matrix is a matrix consisting of the coefficients of the variables in a set of linear equations. As the skilled reader of this document knows, the coefficient matrix is used in solving systems of linear equations.

In this connection it is noted that the coefficients in matrices A and B, respectively, may be constants. Thus, it is to be understood that when the parameters are sample values, the sample value Xl (r-l) represents the amplitude of the parameter XI at the time r-1, and the sample value Xl(r) represents the amplitude of the parameter XI at the time r, which is later than the time r- 1 .

With reference to figure 16 in conjunction with figures 31 and 32, the parameter value Xl(r) may be the polar angle (r), also referred to as FI(r). Moreover, the parameter X2(r) may be the amplitude value Sp(r).

As mentioned elsewhere in this disclosure, value of the polar angle (r), XI (r) may be indicative of a deviation, of the operating point 205, 550 of the pump, from a Best Efficiency Point of operation (See e.g. the disclosure in connection with figure 19A).

Similarly, at a selected operating point, the output vector Y(r) depends on the internal state vector X(r) in accordance with a linear model which may be written as follows:

Y(r) = C * X(r) (eq. 8.2) wherein C is a coefficient matrix.

However, equation 8.2 does not mean that a change in the state X must be immediately conveyed into a change of the state Y, since there may, perhaps sometimes, be a delay from the occurrence of a changed internal state X to the occurrence of a corresponding change of the state Y(r) of the fluid system 52.

Such a delay could be exhibited e.g. when the fluid system includes a long pipe for transporting the pumped fluid such that a system pulsation amplitude Y3 caused by the pulsation event X2 occurs with a delay due to the time it takes for the causing pulsation amplitude X2 to travel through the fluid system 52 to the point where the system pulsation amplitude Y3 is measured.

When operating at a steady state, however, such a delay may be of little or no consequence, and then there appears to be a causal link between the internal state X(r) in the pumping process occurring in the pump 10 at time r and the state Y(r) of the fluid system 52 at the same time r. Thus Equation 8.2 is valid, at least when operating the centrifugal pump 10 at steady state. Referring to equation 8.2, the coefficients in matrix C may be constants. The constant values for the coefficients in matrix C may be set to the derivatives C = dY/dX at a selected operating point XOP, 205, 550. In this connection, reference is made to figures 2B, 16 and 19A as well as figure 32 in conjunction with figure 31 .

With reference to figure 32, the system comprises a monitoring module 150A for generating an internal state vector X of dimension m, wherein m is a positive integer. In an example Dim(X) is at least 1 (one), such that a single parameter value is indicative of the internal state of the pump. In another example Dim(X) is at least 2 (two), such that a combination of two parameter values is indicative of the internal state of the pump.

The parameter values in the internal state vector X may be generated in a manner as disclosed in relation to any of figures 1 A to 31 above.

According to an embodiment, the internal state vector X comprises two internal state parameter values, namely XI and X2, wherein Xl= <P, also referred to as FI; and the parameter X2 = Sp. Thus, according to an embodiment, the parameter X 1 is the polar angle , also referred to as FI, and the parameter X2 is the amplitude value Sp.

As discussed elsewhere in this disclosure, the internal state parameter values Xm, such as XI and X2, are preferably generated as time sequences of sample values Xm(r), such as X 1 (r) and X2(r). Thus, the internal state vector X is preferably generated as a time sequence of internal state vectors X(r).

The at least one internal state parameter value may be one or many selected from the group: Xl = the polar angle <J>, also referred to as FI X2 = the amplitude value Sp

X3 = the speed FROT of rotation of the impeller 20

X4= the vane pass frequency. Thus X4= L * FROT, wherein L is the number of vanes on the impeller, and FROT = X3 is the speed FROT of rotation of the impeller 20.

The above mentioned vane pass frequency X4 is the repetition frequency with which the impeller vanes pass the volute tongue 65 (See figure 2A or 2D). According to an embodiment, the internal state vector X comprises four internal state parameter values, i.e. the internal state vector X is of dimension m=4. According to an example, the four internal state parameter values are as discussed above, i.e. Xl = FI; X2 = the peak amplitude value Sp; X3 = f_ROT; X4 = L * X3, wherein L is the number of vanes on the impeller, and X3 = f_ROT.

The internal state parameter value X2 (also referred to as X2(r), and as Sp, and as Sp(r), and as SFP ) may be a measurement signal amplitude peak value (Sp(r); Sp, SFP) indicative of a dynamic fluid pressure, i.e. a fluid pressure pulsation amplitude. Measurement of this fluid pressure pulsation is discussed elsewhere in this disclosure, e.g. in relation to reference P54 in figures 14A, 14B, 14C; and in relation to references +, - in figures 14E and 14F; and in relation to references +, - in figure 30A.

Thus, the internal state parameter value X2 is indicative of a dynamic fluid pressure generated when the rotating impeller vanes 310 interact with the fluid material 30. The measurement signal amplitude peak value X2, Sp(r); Sp, SFP is repetitive with the vane pass frequency fR, X4. Thus, when the impeller 20 has a first number L of vanes 310, the measurement signal amplitude peak value X2 occurs a first number of times per impeller revolution, i.e. L times per impeller revolution. Thus, the measurement signal amplitude peak value X2 has a repetition frequency fR = L*fROT = X4.

According to examples disclosed in this disclosure, the internal state parameter value X2 is indicative of a dynamic fluid pressure generated in, at, or near, the pump 10.

in the pump 10

As discussed in relation to figures 14E and 14F the measurement signal SE 77 is responsive to a local fluid pressure pulsation in the pump. The local fluid pressure pulsation, discussed in relation to figures 14E and 14F, depends on a local high pressure, indicated by “+” on one side of the rotating vane tip, and on a local low pressure, indicated by

on another side of the rotating vane tip.

The Monitoring Module 150A may be adapted to convey 1 122 information describing the internal state X of the pump during operation of the pump 10, e.g. via a user interface 210, as indicated by arrow 1 122. Thus, one or several values in the internal state vector X may be conveyed to an operator 230 via user interface 210. This advantageously simplifies for the operator 230 of the pump 10 to make suitable adjustments 1124 to set point values (indexed SP) for influencing the input vector U. Thus, by adjusting e.g. the speed set point value UI SP (See fig 32 in conjunction with figure IB) the operator 230 can adjust the speed feoT, U1 .

In this manner the operator, by adjusting one or more relevant set point value(s) USP can adjust the corresponding input variable(s) U1 , U2, U3,... Uk.

The set point values UISP, U2SP, U3SP,... Uk may be collectively referred to as a set point vector Usp. Thus, the dimension of set point vector USP is k: set point vector USP: Dim (USP) = k

The system 5,320,770 of figure 32 may include a Monitoring Module 150A as described in any of the other embodiments described in this disclosure, e.g. in relation to any of figures 1- 31.

Referring to figure 32 in conjunction with e.g. figure 2A, the Monitoring Module 150A enables a method of operating a centrifugal pump 10 having a casing forming a volute 75 in which a rotatable impeller 20 is disposed for urging a fluid material 30 into the volute. The method comprises:

- generating a measurement signal indicative of occurrence of a fluid pressure pulsation event in the fluid;

- generating a reference signal indicative of a rotational reference position of said rotating impeller;

- determining a temporal relation value (FI, FI(r)) based on time of occurrence of said fluid pressure pulsation event (Sp(r)) and said reference signal.

According to an example, with reference to figure 32, the Monitoring Module 150A is coupled to a user interface 210 for conveying 1122 information about a current internal state X of the pump to a user 230, wherein the information includes said determined temporal relation value FI, FI(r), Xl(r). The provision of such information about current internal state X of the pump enables the user 230 to adjust set point values USP for controlling the operation of the pump 10, 10A, 10B. Since the temporal relation value FI, FI(r), Xl(r) is indicative of a current operating point 205 of the pump in relation to a Best Operating Point, the information conveyed 1 122 about the current internal state X of the pump enables the user 230 to adjust the set point values USP so as to cause the pump to run at the Best Operating Point, or at a desired proximity to the Best Operating Point.

Thus, figure 32 is an illustrative example that can be regarded in the light of other examples in this disclosure, e.g. figures 2A, 2B, 24, 25A and 27. Figure 32 can be said to provide a condensed overview of the systems described in connection with several other figures in this disclosure, such as e.g. figures 2A, 2B, 24, 25A and 27.

According to an example, with reference to figure 32, the user interface 210 may be configured to receive (See reference 1124 in figure 32) data indicative of set point values USP for controlling the operation of the pump 10, 10A, 10B. The data indicative of set point values USP may include a rotation speed set point value UI SP, f_ROTsp for controlling a rotational speed U 1 , fpoT of the impeller 20.

According to an example, with reference to figure 32, the data indicative of set point values USP may include a set point value U2SP for controlling an adjustable volute volume of an adaptive pump 10, 10A (See figure 32 in conjunction with figure 24 and/or 25A and/or 25B and/or 27.

Hence, according to an example referring to figure 32, the Monitoring Module 150A enables a method of operating a centrifugal pump 10 having a casing forming an adaptive volute 75 A having an adjustable volume in which a rotatable impeller 20 is disposed for urging a fluid material 30 into the volute. An example method comprises: method comprises:

- determining a temporal relation value (FI, FI(r)) based on time of occurrence of said fluid pressure pulsation event (Sp(r)) and said reference signal; and

- controlling said adjustable volute volume based on the determined temporal relation value FI, FI(r), XI.

Thus, with reference to figure 32, and according to an example when the pump is an adaptive pump, the Monitoring Module 150A is coupled to a user interface 210 for conveying 1122 information about a current internal state X of the adaptive pump to a user 230, wherein the information includes

- data indicative of said determined temporal relation value FI, FI(r), XI, and

- data indicative of the rotational speed X3, FROT of the impeller.

The provision of such information about current internal state XI and X3 of the pump enables the user/operator 230 to adjust set point values USP for controlling the operation of the pump 10, 10A, 10B. In this context it is noted that the flow QOUT is proportional to, or substantially proportional to, the rotational speed X3, f_ROT of the impeller.

Hence, for example, the conveying 1 122 of the above mentioned information enables the operator 230 to

- increase the rotational speed fpor of the impeller by adjusting the corresponding set point value U 1 SP, FROTSP if an increased flow QOUT is desired, or decrease the rotational speed fRoi of the impeller by adjusting the corresponding set point value U I SP, FROTSP if a decreased flow QOUT is desired.

Moreover, the conveying 1122 of the above mentioned information enables the operator 230 to adjust the set point value U2SP, also referred to as VPSP, so as to change the volume of the adaptive volute dependent on the conveyed temporal relation value FI, Fl(r) when the pump runs at the desired impeller speed FROT, thereby causing the adaptive pump run at the Best Operating Point, or at a desired proximity to the Best Operating Point while also delivering the desired flow QOUT.

Figure 33 is a block diagram of another system 730, 940, 950 including a centrifugal pump illustrated as a black box 10 receiving a number of inputs Ul, ... Uk, and generating a number of outputs Yl, ... Yn. The system 940 of figure 33 may include a Monitoring Module 150A as described in any of the other embodiments described in this disclosure, e.g. in relation to any of figures 1-31. Moreover, the system 940 of figure 33 may include a control module 150B as described in any of the other embodiments described in this disclosure, e.g. in relation to figure 26 and/or figure 28.

The Monitoring Module 150A of figure 33 may be adapted to convey information (See ref 1 122 in figure 33) describing the internal state X of the pump during operation of the pump 10, e.g. via a user interface 210. Thus, one or several values in the internal state vector X may be conveyed 1 122 to an operator 230 via user interface 210, as indicated by arrow 1 122. This advantageously simplifies for the operator 230 of the pump 10 to make suitable adjustments 1 126 to pump set point values U and/or internal state reference values XREF (indexed REF) for influencing the internal state X of the pump during operation of the pump 10. Arrow 1 126 indicates user input relating e.g. to a desired internal state XREF. The internal state reference parameters XI REF, X2REF, X3REF,..., XHIREF may be collectively referred to as an internal state reference vector X REF.

The dimension of internal state reference vector XREF is m:

Internal state reference vector XREF: Dim (XREF) = m

In this manner the operator 230, by adjusting pump set point values U and/or relevant internal state reference parameter value(s) XI REF, X2REF, X3REF,..., XHIREF can influence the internal state X of the pump during operation of the pump 10. Thus, the user interface 210, in response to user input, may be configured to generate values for the internal state reference vector X

REF.

According to an embodiment, the internal state reference vector XREF comprises two internal state parameter reference values, namely XI REF and X2REF, wherein X 1 REF= O EF, also referred to as FIREF; and the parameter reference value X2REF = SPREF. Thus, according to an embodiment, the parameter reference value XI EF is the polar angle reference value OREF, also referred to as FIREF, and the parameter reference value X2REF is the amplitude reference value SpREF.

As discussed elsewhere in this disclosure, the parameter reference values X I REF and X2REF are preferably generated as time sequences of sample values XlREF(r) and X2REF(r), respectively. Thus, the internal state reference vector XREF is preferably generated as a time sequence of internal state reference vectors XREF(r), wherein r denotes time.

The internal state reference vector X REF is delivered to a reference input of a Control Module 150B, as illustrated in figure 33. Referring to figure 33 in conjunction with figure 26, the Control Module 150B is a multivariable Control Module that also receives, from the Monitoring Module 150A, the above described internal state vector X.

In this connection, the internal state vector X may be indicative of a current state of a pumping process in the pump 10, and the internal state reference vector X REF is indicative of a desired state of the pumping process.

The multivariable Control Module 150B may be adapted to generate, based on the received internal state reference vector X REF and the received internal state vector X, an internal state error vector X ERR.

The internal state error vector X ERR includes internal state error values XI ERR, X2 ERR, X3ERR,..., XmERR

The dimension of internal state error vector XERR is m:

Internal state error vector XERR: Dim (X ERR) = m

According to an embodiment, in analogy with the above described internal state reference vector XREF and the above described internal state vector X, also the internal state error vector XERR comprises two internal state parameter error values, namely XI ERR and X2ER , wherein XI ERR = ® ERR, also referred to as FIERR; and the parameter error value X2ERR = SPERR.

In analogy with the above described internal state reference vector XREF and the above described internal state vector X, the internal state error vector XERR is preferably generated as a time sequence of internal state internal state error vectors XERRC , wherein r denotes time.

The error vector is delivered to regulator 755, 755C. The regulator 755, 755C of figure 33 is a multivariable regulator adapted to generate a set point vector Usp. Accordingly, the set point vector USP includes the above described set point value(s) for controlling or adjusting corresponding input variable(s) Ul, U2, U3,... Uk (See fig 33 in conjunction with figure 34). Thus, the system described in relation to Figure 33 advantageously simplifies for the operator 230 of the pump 10 by conveying 1122 information indicative of the internal state X of the pump during operation, while also allowing the operator to provide 1126 information describing a desired internal state, e.g. in the form of reference values for the above described internal state reference vector X REF.

The regulator 755, 755C may be a multi-variable regulator configured to include a multivariable proportional-integral-derivative controller (PID controller). Alternatively, the regulator 755, 755C may be configured to include a multi-variable proportional-integral controller (PI controller). Alternatively, the regulator 755, 755C may be configured to include a multi-variable proportional controller (P controller).

Alternatively, the regulator 755, 755C may be configured to include Kalman filtering, also known as linear quadratic estimation (LQE). Kalman filtering is an algorithm that uses a series of measurements observed over time, including statistical noise and other inaccuracies, and produces estimates of unknown variables that tend to be more accurate than those based on a single measurement alone, by estimating a joint probability distribution over the variables for each timeframe.

The system described in relation to Figure 33 advantageously enables a method of operating a centrifugal pump 10 having a casing forming a volute 75 in which a rotatable impeller 20 is disposed for urging a fluid material 30 into the volute. The method comprises:

- monitoring a fluid pressure pulsation event inside the pump casing;

- generating, based on said monitoring, a measurement signal indicative of occurrence of said fluid pressure pulsation event;

- generating a reference signal indicative of a rotational reference position of said rotating impeller; and

- determining an internal state vector X including a temporal relation value XI, FI, FI(r) based on time of occurrence of said fluid pressure pulsation event Sp(r) and said reference signal. According to an example, with reference to figure 33, the Monitoring Module 150A is coupled to a user interface 210 for conveying 1122 information about a current internal state X of the pump to a user 230, wherein the information includes said determined temporal relation value FI, FI(r), Xl(r).

The provision of such information about current internal state X of the pump to the user 230 enables the user 230 to input data indicative of a desired internal state XREF of the pump 10, 10A. Arrow 1126 in figure 33 indicates user input relating e.g. to a desired internal state XREF. The internal state reference parameters XIREF, X2REF, X3REF,..., XI IREF may be collectively referred to as an internal state reference vector X REF. Thus, figure 33 is an illustrative example that can be regarded in the light of other examples in this disclosure, e.g. figures 26, 28 and 29. Figure 33 can be said to provide a condensed overview of the systems described in connection with several other figures in this disclosure, such as e.g. figures 26, 28 and 29.

According to an example, with reference to figure 33, the user interface 210 may be configured to receive (See reference 1126 in figure 32) data indicative of a desired internal state XREF of the pump 10, 10A.

As mentioned above, the system described in relation to Figure 33 advantageously enables a method of operating a centrifugal pump 10 having a casing forming a volute 75 in which a rotatable impeller 20 is disposed for urging a fluid material 30 into the volute. That method may advantageously further comprise: generating, by said control module 150B, an operating point error value (FlERR(r) ) based on said operating point reference value (FlREF(r) ), and said first temporal relation (R (r); TD; FI(r)), wherein said operation parameter is based on said operating point error value (FIERRO-) ).

Figure 34 shows another somewhat diagrammatic view of a system 1130 including a centrifugal pump 10. Thus, reference numeral 1130 relates to a system including a pump 10 having an impeller 20, as discussed in this document. The system 1130 of figure 34 may include parts, and be configured, as described above in relation to figure 1 A and/or figure IB and/or as described in any of the other examples described in this disclosure, e.g. in relation to figures 2A-33. The Monitoring Module 150A may include status parameter extractor functionality as described elsewhere in this document for generating internal state parameter values XI, X2, X3,..., Xm. It is to be noted that the internal state X of the pump 10, at a point in time termed r, can be referred to as X(r). That internal state X(r) can be described, or indicated, by a number of parameter values, the parameter values defining different aspects of the internal state X(r) of the pump 10 at time r. Thus, values of the internal state parameters XI, X2, X3,..., Xm at the time r may be collectively referred to as an internal state vector X(r).

The system illustrated in Figure 34 may provide an integrated HCI 210, 250, 210S. Thus, the input/output interface 210, 210B of Figure 34 may be configured to enable all the input and/or output described above. Additionally, the input/output interface 210 of figure 34 may be configured to provide 1132 information relating to a state of the fluid system 52. The state of the fluid system 52 may be described by the output parameters ¥1, Y2, ¥3, ... Yn, collectively referred to as output vector Y. As mentioned above, the dimension of output vector Y is n:

Output vector Y : Dim (Y) = n

The vector Y may also be referred to as fluid system state vector Y.

System 1130 of figure 34 includes a regulator 1 190. The regulator 1190 may be configured to enable all functions described with reference to regulator 240, which is described elsewhere in this document. Alternatively, regulator 1190 may be configured to enable all functions described with reference to control module 150B, which is described elsewhere in this document. Alternatively, regulator 1190 may be configured to enable all functions described with reference to regulator 755, which is described elsewhere in this document. In addition to functions described in regulator 240 and/or regulator 755 the regulator 1 190 may be configured to perform additional functions, such as e.g. to convey and/or receive information relating to the state of the fluid system 52, e.g. in the form of output parameters Yl, Y2, Y3, ... Yn. Thus regulator 1190 may also be referred to by reference number 240C and/or 755C.

Thus, regulator 1190 may be configured to convey information relating to the state of the fluid system 52 to a pump operator 230, as indicated by arrow 1132. Moreover, regulator 1190 may be configured to receive, from a pump operator 230, information relating to a desired state of the fluid system 52, as indicated by arrow 1 196.

Figure 35 is a schematic general overview of information that may be conveyed by input/output interface 210 of Figure 34. With reference to figures 34 and 35 it is noted that the regulator 1 190, 755C of fig. 34 is coupled, via coupling 1 100, for data exchange with input/output interface 210. Information to be transferred via coupling 1 100 includes reference values for the above described internal state reference vector X REF.

Referring to figure 34, the system 1 130 comprises a fluid system analyzer 1 140 configured to analyze at least one part of said fluid system 52. The analyzer 1 140 is configured to generate at least one system parameter value Yl, Y2, Y3, ... Yn based on said fluid system analysis. In effect, the at least one system parameter measurement value Yl , Y2, Y3, ... Yn may be indicative of a fluid system state Y, the fluid system state Y being a momentary state of the fluid system 52. When analyzer 1 140 provides two or more system parameter measurement values, these values may be provided in the form of the above mentioned output vector Y.

The momentary state of the fluid system 52, i.e. the fluid system state Y, may be identified by measurement of at least one system parameter measurement value Yl, Y2, Y3, ... Yn. In practice it may be desirable to generate more than one system parameter measurement value in order to obtain information indicative of the fluid system state Y.

The at least one system parameter measurement value may be one or many selected from the group:

- a value Yl indicative of a fluid system back pressure. The value Yl may be a static pressure, such as the pressure in the fluid at the pump outlet 66.

- a value Y2 indicative of a fluid flow from the pump outlet 66, also referred to as QOUT into a first region 54 of the fluid system 52 (See e.g. figures 1 A, IB and/or 2A).

- a value Y3 indicative of a first fluid system pulsation amplitude having a repetition frequency Y4 that equals the vane pass frequency X4 of the pump 10, i.e. X4= L * .f_ROT

- a value Y4 indicative of a repetition frequency of the first fluid system pulsation amplitude Y3, i.e. Y4= X4= L * f_ROT, where L is the number of vanes on the impeller. - a value Y5 indicative of a second temporal relation value, or second phase value Fh. The second phase value Y5, FI2 is indicative of a phase between the repetitive position reference signal values relating to pump 10 and the repetitive first fluid system pulsation amplitude Y3.

- a value Y6 indicative of a second fluid system pulsation amplitude. The second pulsation amplitude value Y6 is indicative of the highest pulsation amplitude in the fluid system 52, irrespective of frequency.

- a value Y7 indicative of a second repetition frequency of the second fluid system pulsation amplitude Y6.

- a value Y8 is set to indicate when the second repetition frequency Y7 equals the vane pass frequency X4 of the pump 10.

- a value Y9 indicative of a fluid system pressure, such as a static pressure, in the fluid system 52. The value Y9 may be indicative of a fluid system pressure P54S (See figure 36A) at the outlet 66D of pump embodiment 10D.

- a value Y 10 indicative of a fluid flow in the fluid system 52. The value Y 10 may be indicative of a fluid system flow Q_OUTS (See figure 36A) from the outlet 66D of pump embodiment 10D. Acccording to an embodiment, the value Y10 may be indicative of a flow Y10 into the fluid system 52 from a controllable valve, such as from a valve arrangement 1220 (See figure 36A).

- a value Y1 1 indicative of a relation between the first fluid system pulsation amplitude value Y3 and the pulsation amplitude X2. According to an example the relation Y1 1 may be generated by dividing the first fluid system parameter value Y3 by the pump internal state parameter value X2, i.e.

Yl l = Y3/X2

The relation value Y1 1 is of interest as a system parameter value since the first fluid system pulsation amplitude value Y3 has a repetition frequency Y4 that equals the vane pass frequency X4 of the pump 10. The frequency X4 is the frequency of the pulsation amplitude X2.

As discussed elsewhere in this disclosure, the internal state parameter value X2 (also referred to as X2(r), and as Sp, and as Sp(r), and as SFP ) is a measurement signal amplitude peak value (Sp(r); Sp, SFP) indicative of a dynamic fluid pressure pulsation (see reference P54 in figures 14A, 14B, 14C; and references +, - in figures 14E and 14F) generated when the rotating impeller vanes 310 interact with the fluid material 30. The measurement signal amplitude peak value X2, Sp(r); Sp, SFP is repetitive with the vane pass frequency fR, X4. Thus, when the impeller 20 has a first number L of vanes 310, the measurement signal amplitude peak value X2 occurs a first number of times per impeller revolution, i.e. L times per impeller revolution. Thus, the measurement signal amplitude peak value X2 has a repetition frequency fR = L*fROT = X4.

As mentioned earlier, the fluid system back pressure U3 may be equal to the pressure Y1 (See figure 31). The fluid system back pressure Yl , U3, may be measured at or near the outlet 66 of the pump, and thus it may be equal to the pressure P54, as illustrated e.g. in figure 1 A, IB and/or 2A and/or figure 31 . Thus, the system back pressure U3 may be equal to the pressure Yl :

U3 = Yl = P₅₄

Likewise, the input parameter U4 may be equal to the flow Y2 from the outlet 66, also referred to as QOUT (See e.g. figure 2A and/or figure 31):

U4 - Y2 = QOUT

However, it is noted that when the parameter X 1 and/or X2 is/are generated as disclosed in this disclosure, the operating point 205 which depends on the flow Y2 and the pressure Yl (See fig. 2B), there is no need to measure the actual flow Y2 or pressure Yl .

However, to the extent that system parameter measurement values are required, the system parameter measurement values, such as above mentioned values Y3 to Y10, may be obtained by appropriate sensors. Such appropriate sensors may include pressure sensors and/or flow meters. Sensors as those described above in connection with figure 2B may be used for obtaining at least some of the system parameter measurement values.

According to an example, pressure pulsations forming basis for the value Y3 may be measured by a sensor 70Y (See figure 34 part 2). The sensor 70Y may be a sensor as described above in connection with figure 2B, such as a sensor configured to detect e.g. pressure, vibration and/or strain.

An embodiment of the sensor 70Y is a pressure sensor for generating a measuring signal dependent on fluid pressure pulsation PFP in the fluid 30. Such a sensor may be configured and mounted to measure fluid pressure pulsation in the fluid material consumer 50 (See figure 34 part 2). The pressure sensor may be mounted so as to detect a fluid pressure pulsation PFP in said fluid material 30. The pressure sensor 70 may, for example, be embodied by a commercially available sensor sold under the brand ICP® PRESSURE SENSOR, Model 121A41.

According to an example the fluid system analyzer 1 140 may include a system monitoring module 150AY. The system monitoring module 150AY may be of the same type as the monitoring module 150A described elsewhere in this disclosure.

With reference to figure 34, the system monitoring module 150AY may be coupled to receive a measurement signal SEAY from a vibration sensor 70Y. The vibration sensor 70Y may be configured to measure vibration at a location in the fluid system. In one example, the vibration sensor 70Y is configured to measure a vibration that depends on a fluid pressure pulsation in the fluid material consumer 50 (See Figure 34). As mentioned earlier, the fluid material consumer 50 may include a headbox 50A, also referred to as head tank, whose purpose is to maintain a constant head (i.e. constant pressure) on fiber slurry.

According to an example, the system monitoring module 150AY is coupled to receive the same position signal Ep delivered to monitoring module 150A (See figure 34). This advantageously enables the system monitoring module 150 AY to treat the measurement signal SEAY from vibration sensor 70Y with a position reference that is same, or synchronized with, the reference signal discussed above in relation to any of figures 1 A to 35. Thus, the system monitoring module 150AY may be configured to generate the above mentioned value Y3 indicative of a first fluid system pulsation amplitude based on the measurement signal SEAY and the position signal Ep.

Moreover, the system monitoring module 150AY may be configured to generate the above mentioned value Y5 indicative of a second temporal relation value Fb based on the measurement signal SEAY and the position signal Ep.

In this manner the second phase value Y5, Fb is indicative of a phase between the repetitive position reference signal values, based on detected rotational position of the impeller and the repetitive first fluid system pulsation amplitude Y3. The fluid system analyzer 1 140 may thus be configured to analyze at least one part of said fluid system 52 so as to generate at least one system parameter value Yl, Y2, Y3, ... Yn based on said fluid system analysis. The at least one system parameter value Yl , Y2, Y3, ... Yn may be provided with information indicative of a point in time when the at least one system parameter value Yl , Y2, Y3, ... Yn was generated.

Moreover, the fluid system state Y, at a point in time termed w, can be referred to as Y(w). That fluid system state Y(w) can be described, or indicated, by a number of parameter values Yl(w), Y2(w), Y3(w), ... Yn(w), the parameter values defining different aspects of the state of the fluid system 52 coupled to the pump 10 at time w. Thus, values of the fluid system parameter values Yl , Y2, Y3, ... Yn at time w may be collectively referred to as fluid system state vector Y(w), also referred to as output vector Y(w).

As noted above, there is a causal relationship between a certain internal state X(r) and a certain fluid system state Y(r), and thus the state Y of the fluid system 52 can be regarded as a function of the internal state X of the centrifugal pump 10.

Referring to figure 34, the output vector Y may be delivered to a first input of a correlator 150C 1 . Moreover, the internal state vector X may be delivered by the module 150A to a second input of the correlator 150C1. The correlator 150C1 is configured to identify a correspondence between the internal state X and the corresponding output Y.

However, in order to perform a correlation it is desirable to ensure that a measured value of the output Y(w) refers to, at least approximately, the same point in time as the internal state X(r). In other words, the values in the internal state vector X(r) may need to be synchronized with the values in the corresponding output vector Y(w). Referring to figure 34, the output vector Y(w) may be delivered to a first input of an optional synchronizer 1 150. The synchronizer 1 150 is optional because it may not be needed, e.g. when the internal state vector X(r) and the corresponding output vector Y(w) are generated in a synchronized manner such that

- the point in time w is the same point in time as the point in time r, or

- such that the point in time w is at least approximately the same point in time as the point in time r. Temporally Synchronized vectors X(t) and Y(t) are received by a correlation data generator 1 160, as illustrated in figure 34.

The correlation data generator 1 160 generates a correlation data set 1 170. According to an example, the correlation data generator 1 160 generates a correlation data set by performing correlation of a received at least one status parameter value, such as e.g. phase value Xl (t) and a received at least one corresponding system parameter value, such as e.g. fluid system pulsation Y3(t).

According to another example, the correlation data generator 1 160 generates a correlation data set by performing correlation of a received at least one status parameter value, such as e.g. impeller speed X3(t) and a received at least one corresponding system parameter value, such as e.g. fluid system pulsation Y3(t).

The synchronizer 1 150 may receive a number of time stamped internal state vectors X(r) and a number of time stamped corresponding output vector Y(w). The received information vectors may be received in a temporally interleaved fashion such as X( 10), Y(12), X(14), Y(16), X(18), Y(20), X(22), Y(24), wherein the synchronizer 1 150 receives a vector X in a time period between the reception of two consecutive vectors Y. That is the case e.g. when vector X(18) is time stamped in the time period between t=20 and t=l 6, and the Y-vectors Y(16) and Y(20), respectively, are time stamped at the points in time t=l 6 and t=20. When operating the pump 10 at a steady state condition, i.e. when all the values in vectors X and Y are stable over time, the synchronizer 1 150 may generate pairs of vectors X and Y by adjusting the time stamps so that a generated pair of vectors X and Y have the same time stamp. That same time stamp may e.g. be an intermediate time stamp. For example, the synchronizer 1 150 when receiving the above mentioned vectors X( 18) and Y(20) may arrange them as a vector pair stamped with an intermediate time t= 19. Thus, the synchronizer 1 150 may, in response to reception of vectors X(t) and Y(t+2) generate a vector pair X(t+1 ) and Y(t+1) for delivery to correlation data generator 1 160. Moreover, the delivery frequency of the X-vectors and the Y-vectors from monitoring module 150A and system analyzer 1 140, respectively, to the correlator 150C1 may be different. For example, the analyzer 1 140 may deliver system measurement values Y at a higher rate than rate at which the monitoring module 150A delivers pump state parameters X.

This problem may be addressed, for example, by configuring the synchronizer 1 150 to deliver, to correlation data generator 1 160: pairs of received vectors X and Y such that each time stamped vector Y is associated with that vector X having the closest earlier time stamp. As a consequence, the synchronizer 1 150 may have to discard or reject some vectors.

Thus, for example, when the delivery frequency of the X- vector is lower than the delivery frequency of the Y-vector, the synchronizer 1 150 may receive vectors as follows: vector X(34), vector Y(36), vector X(37), vector Y(38), vector X(40), vector Y(40), vector Y(42) vector X(43), vector Y(44), then the synchronizer 1 150 may deliver, to correlation data generator 1 160, pairs 1165 of vectors X and Y such that each time stamped vector Y is associated with that vector X having the closest earlier time stamp. In the above example, the following pairs could be delivered by synchronizer 1 150: vector X(34) vector Y(36), vector X(37), vector Y(38), vector X(40), vector Y(40), vector X(43), vector Y(44), and as a consequence vector Y(42) may be discarded.

Table 7 below is an example of successive pairs 1 165 of vector values XI and Y3 arranged in temporal order.

Table 7: Successive pairs 1165 of vectors X and Y arranged in temporal order.

The example of successive pairs 1165 of vectors XI and Y3, illustrated by table 7, includes information indicative of an operating point XI of the pump (also referred to by temporal relation value FI and reference 205) and information indicative of a corresponding output parameter value Y3. The output parameter Y3 is indicative of an amplitude of a fluid pulsation in the fluid system 52.

The correlation data generator 1160, may be configured to perform a correlation based on received pairs 1165 of vectors X and Y. According to an example the correlation data generator 1160 may be configured to perform a regression analysis based on a large number of received pairs 1 165 of vectors X and Y.

The regression analysis may use one or several statistical processes for estimating the relationships between the dependent variables, i.e. the values in the vector Y and one or more independent variables, i.e. the values in the vector X.

Figure 36A shows a schematic block diagram of yet another embodiment of a process monitoring system. Reference numeral 1210 relates to a pump location with a pump 10 having an impeller 20, as discussed above in relation to preceding drawings in this document. The process monitoring system 1210 of figure 36A may include parts, and be configured, as described in any of the other embodiments described in this disclosure. In particular, the monitoring apparatus 150, also referred to as monitoring module 150A, shown in figure 36A may be configured as described in any of the other embodiments described in this disclosure. The process monitoring system 1210 illustrated in figure 36A may include a control module 150B, as described above e.g. in connection with figure 26.

Reference numerals 10 and 10A in figure 3 A are to be understood as relating to a centrifugal pump 10 or an adaptive centrifugal pump 10A, such as described above. Reference numeral 52 in figure 36A is to be understood as relating to a fluid system 52, such as described above. Reference numeral 10D in figure 36A is an illustration of a combination of a pump 10, or 10A, and a valve arrangement 1220. The valve arrangement 1220 is illustrated in more detail in figure 36B.

Referring to figures 36A and 36B, a method for monitoring and/or operating a centrifugal pump is disclosed. The pump 10, 10A has a casing forming a volute 75 in which a rotatable impeller 20 is disposed for urging a fluid material 30 via the volute to a pump outlet 66. The pump outlet 66 is coupled to a fluid system 52 via a valve arrangement 1220. The valve arrangement 1220 may include valves VL and VH. An example method comprises receiving a measuring signal SEA indicative of a fluid pressure pulsation (PFP) in the fluid material (30); receiving a reference signal Ep indicative of a rotational reference position of the rotating impeller; and generating data indicative of an internal state of the centrifugal pump 10, 10A, said data including a phase value (FI, Fl(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)) based on said measuring signal and said reference signal.

The valve arrangement 1220 (VL; VH) may comprise a first flow control valve (VLS) having a first adjustable cross sectional area (A VLS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52). Moreover, the valve arrangement 1220 (VL; VH) may comprise a second flow control valve (VLR) having a second adjustable cross sectional area (AVLR ) for controlling another flow (QR), such as for example a return flow (QR). The return flow (QR) is diverted from flowing to the fluid system 52. The at least one set point parameter (U I SP, U2SP) comprises a first valve set point value (U2SP, U2ASP) for simultaneously controlling said first adjustable cross sectional area (AVLS ) and said second adjustable cross sectional area (AVLR ).

The another flow (QOUTR) may be a return flow for returning fluid to a fluid storage or for returning fluid to an inlet side of the pump 10, 10A.

As mentioned elsewhere in this disclosure, the phase value (FI, FI(r), Xl(r)) may be indicative of a current operating point of the pump in relation to a Best Efficiency Point of operation. It is noted that the phase value may also be referred to as temporal relation value.

An example method comprises determining an operation parameter of the pump based on the determined temporal relation value (FI, FI(r)).

Referring to figure 36A, according to an example, a rotation speed set point value (UISP, IROTSP) affects pump outlet fluid pressure (Yl, P5 ) and/or pump outlet fluid flow (Y2, QOUT) at said pump outlet (66). The rotation speed set point value (UISP, f_ROTSP) may be based on a desired system delivery flow (YI OREF, Q_OUTSREF) and on said phase value (FI, FI(r), XI (r)) and/or temporal relation value (FI, FI(r), X 1 (r)).

Referring to figure 36A, according to an example, the first valve set point value (U2SP, U2ASP) is initially set so that said system delivery flow (Y10, Q_OUTS) is equal to said pump outlet fluid flow (Y2, QOUT), for example by simultaneously controlling said first adjustable cross sectional area (AVLS ) and said second adjustable cross sectional area (AVLR ) so as to direct all, or substantially all, of said pump outlet fluid flow (Y2, QOUT) to said fluid system (52).

Referring to figure 36A, according to an example, when said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow, then said rotation speed set point value (UISP, f_ROTSP) is adjusted to increase said impeller rotational speed (Ul, fRoi). Referring to figure 36A, according to an example, when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow, then said rotation speed set point value (UISP, FROTSP) may be adjusted to increase said impeller rotational speed (Ul, f_ROT) until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YI OREF, Q_OUTSREF). In this connection, it is noted that the flow QOUT from a centrifugal pump 10 is proportional, or substantially proportional to the impeller rotational speed fpoi .

Figure 36C is a plot illustrating an example of how the operating point 205 depends on impeller speed, pressure Yl, and flow Y2. The pressure Y1 is referred to as Head in figure 36C.

Figure 36D is a plot illustrating an example of how the pulsation amplitude X2 depends on operating point 205, also referred to as duty point 205. In particular, it is noted that in the example of Figure 36D the pulsation amplitude X2 is at a minimum at BEP flow, and in the example BEP flow was about 4500 cubic metres per hour. It is noted that in figure 36D the current operating point 205 of the pump is at a lower flow than the BEP flow. In fact the current flow Y2, QOUT appears to be less than 4000 cubic metres per hour, and the momentary phase value FI, XI indicates a current operating point 205 with a lower pump outlet fluid flow Y2, QOUT than Best Efficiency Point of flow Q_OUTBEP. The vertical axis on the right hand side of figure 36D shows the amplitude X2 of the detected pulsation, and as indicated the pulsation amplitude increases with the deviation from BEP flow. In this connection, see also figure 19A wherein amplitude X2 and phase FI, FIDEV are also illustrated.

Referring to figure 36A in conjunction with figure 36D, according to an example, when said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) with a lower pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YIOREF, Q_OUTSREF); then said rotation speed set point value (UISP, FROTSP) is adjusted to increase said impeller rotational speed (Ul, FROT), e.g. until said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said first valve set point value (U2SP, U2ASP) is adjusted so as to increase said another flow (QR) .

In this manner, for example, an oversized pump that was running at a speed of revolution below BEP flow is operated to increase pump outlet fluid flow (Y2, QOUT), thereby allowing the pump to run at a more energy efficient point of operation 205 at or near BEP flow, and a surplus flow, i.e. a difference between pump outlet fluid flow at BEP (Y2BEP, Q_OUTBEP) and the system delivery flow (Y10, Q_OUTS), may be directed as a return flow.

Figure 36E is another plot illustrating an example of how the pulsation amplitude X2 depends on operating point 205, also referred to as duty point 205. In particular, it is noted that in the example of Figure 36E the pulsation amplitude X2 is at a minimum at BEP flow, and in the example BEP flow was about 4500 cubic metres per hour. It is noted that in figure 36E the current operating point 205 of the pump is at the BEP flow, and the amplitude of the detected pulsation X2 is at a minimum. The vertical axis on the right hand side of figure 36D shows the amplitude of the detected pulsation X2, and as indicated the pulsation amplitude increases with the deviation from BEP flow. It is noted that the phase value FI, XI appears to change sign when flow passes the BEP flow. In this connection, see also figure 19A wherein amplitude X2 and phase FI, FIDEV is also illustrated.

Referring to figure 36A, according to an example, when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with pump outlet flow (Y2, QOUT) at, or substantially at, Best Efficiency Point of pump outlet flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YI OREF, Q_OUTSREF); then said first valve set point value (U2SP, U2ASP) may be adjusted so as to minimize, or eliminate, said another flow (QR). This is advantageously done in order to minimize return flow (QR). However, when the first valve set point value (U2SP, U2ASP) is adjusted so as to minimize, or eliminate, said another flow (QR), then this may lead to a higher system delivery flow (Y10, Q_OUTS).

In this connection it is noted that the phase value (FI, FI(r), X 1 (r)) is indicative of the current Operating Point (205) in relation to BEP. Thus, the impeller position at the moment of occurrence of the fluid pressure pulsation amplitude peak value (Sp, P54, P77) is indicative of the current Operating Point (205) in relation to BEP.

Referring to figure 36A, according to an example, when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a flow Y2 at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is higher than to a desired system delivery flow (YIOREF, Q_OUTSREF); then said rotation speed set point value (UISP, f_ROTSP) is adjusted to decrease said impeller rotational speed (U 1 , f_ROT), e.g. until said system delivery flow (Y 10, Q_OUTS) corresponds to a desired system delivery flow (YI O EF, Q_OUTSREF).

Figure 36F is yet another plot illustrating an example of how the pulsation amplitude X2 depends on operating point 205, also referred to as duty point 205. In particular, it is noted that in the example of Figure 36F the pulsation amplitude X2 is at a minimum at BEP flow, and in the example BEP flow was about 4500 cubic metres per hour. It is noted that in figure 36F the current operating point 205 of the pump is at a higher flow than the BEP flow. In fact, the current flow Y2, QOUT appears to be more than 5000 cubic metres per hour, and the phase value FI indicates a current operating point (205) with a higher pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP). The vertical axis on the right hand side of figure 36F shows the amplitude of the detected pulsation X2, and as indicated the pulsation amplitude increases with the deviation from BEP flow. In this connection, see also figure 19A wherein amplitude X2 and phase XI, FI, FIDEV is also illustrated.

Referring to figures 36A and 36B, according to an example, said valve arrangement (VL; VH) comprises a third flow control valve (VH) having a third adjustable cross sectional area (AVHS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52). According to an example, said at least one set point parameter (Ulsp, U2SP) comprises a second valve set point value (U2SP, U2BSP) for controlling said third adjustable cross sectional area (AVHS ).

Referring to figures 36A and 36B, according to an example, when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a higher pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow Q_OUTBEP (See figure 36F) then said second valve set point value (U2SP, U2BSP) may be adjusted so as to reduce said third adjustable cross sectional area (AVHS ).

It is noted that a reduction of the third adjustable cross sectional area (AVHS ) will cause a reduced pump outlet fluid flow (Y2, QOUT) and an increased pump outlet fluid pressure (Yl, P54). In this manner, for example, a pump that was running at back pressure Y 1 below BEP back pressure (Y 1 BEP) is operated to increase pump outlet fluid pressure (Y 1 , P54), thereby allowing the pump to run at a more energy efficient point of operation 205 at or near BEP pressure (YI BEP), and a surplus pressure, i.e. a difference between pump outlet fluid pressure (Yl, P54) at BEP (YI BEP) and the system delivery Head (P54S), is exhibited as a pressure difference across the flow control valve (VH).

However, it is noted that the resulting reduced pump outlet fluid flow (¥2, QOUT) may render a system delivery flow (Y 10, Q_OUTS) to the fluid system (52) that is lower than a desired system delivery flow (Y I OREF, Q_OUTSREF).

Referring to figures 36A and 36B, according to an example, when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a flow Y2 at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is lower than to a desired system delivery flow (YIOREF, Q_OUTSREF); then said rotation speed set point value (UISP, f_ROTSP) may be adjusted to increase said impeller rotational speed (Ul , f_ROT), e.g. until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF).

Referring to figure 36A, an example system may comprise: an apparatus 150, or monitoring module 150A, 450, for monitoring an internal state X of a centrifugal pump 10; 10A having a volute; a valve arrangement VL; VH; a sensor 70 for generating a measuring signal SEA, SFP; SMD, Se(i), S(j), S(q) indicative of a fluid pressure pulsation Ppp in fluid 30 in the volute or in the pump outlet 66, or in a pipe 54 connecting the pump outlet 66 with the valve arrangement VL; VH; a device 170, 180 for generating a reference signal indicative of a rotational reference position of a rotating impeller 20 in the pump 10; and a control module 150B, 755. In this connection, reference may also be made to numbered example 301 below. The above listed combination of parts may advantageously be provided as a kit of parts for curing operational problems arising in an existing pump-and- fluid-system-set up. Referring to figures 1 A and 36D, for example, the inventor has noted that in many industries where a fluid system 52 is fed with fluid 30 from a centrifugal pump 10, the installed pump 10 is often operated at an operating point 205 with a flow Y2 below the BEP flow, as illustrated in figure 36D.

In this context, it is noted that during operation of a centrifugal pump, the fluid 30 is forced to exit the pump outlet 66 thereby causing a fluid material flow QOUT from the pump outlet 66. The “flow QOUT for which the pump was designed” may also be referred to as the flow Q_OUTBEP which is the flow at the Best Efficiency Point (BEP) of the pump.

Efficiency can be measured as the ratio of useful output to total input, which can be expressed with the mathematical formula e = Pu/C, where Pu is the amount of useful output ("product") produced per the amount C ("cost") of resources consumed. This may correspond to a percentage, e%, if products and consumables are quantified in compatible units. In the case of a centrifugal pump where the impeller 20 is caused to rotate by an electric motor, the cost C may be measured by the electric power consumed by the electric motor 715 (See eg. motor 715 in figure 30C or in figure 24).

The amount of useful output Pu, in this context, may be pumped volume of liquid. Thus, the pump efficiency e may be measured as the ratio of pumped fluid volume per unit of electric power fed to the the electric motor 715 (See eg. motor 715 in figure 30C or in figure 24), e.g cubic metres of fluid per Watt (m³/W).

Figure 36G illustrates an example of a pump-and-fluid-system-combination wherein the system curve 209 is a substantially horizontal line at a system head Y1 of 44 meters. Thus, in the example, the desired system back pressure Y I REF, or desired head, is at about 44 meters. As indicated in figure 36G, the efficiency at BEP-flow is e= 90,3% in the example of figure 36G, and the efficiency e decreases when the centrifugal pump 10 operates away from BEP. Thus, the centrifugal pump power consumption per pumped volume increases when the centrifugal pump 10 operates away from BEP. A fluid system curve 209 effectively being a straight line, i.e. constant head Yl, as illustrated in figure 36G, is commonly used e.g. for cooling water in a steel works. In a steel works, the required flow of cooling water is sometimes low because only a few valves are opened to supply cooling water to a few fluid material consumers 50, and sometimes the required flow is high because a larger number of valves are opened to supply cooling water to a larger number of fluid material consumers 50. By providing a constant head Yl (pressure Yl) of the cooling water, an adequate flow of cooling water can be provided to each fluid material consumer 50.

Figure 36H illustrates an example of a pump-and-fluid-system-combination wherein the system curve 209 is curved. In the example illustrated in Figure 36H, the current operating point 205 is at an actual flow Y2, QOUT which is lower flow than BEP flow, and thus the efficiency is far from the best efficiency. The vertical axis on the right hand side of Figure 36H indicates efficiency, and the current operating point 205 provides an efficiency of about 50%.

With reference to figure 36A, an example system 1210 may comprise an apparatus 150A including a status parameter extractor 450, 450i and/or 450i for monitoring an internal state of a centrifugal pump. The centrifugal pump 10 has a casing 62 (as shown i other figures) forming a volute 75 in which a rotatable impeller 20 is disposed for urging a fluid 30 via the volute to a pump outlet 66 which is coupled to an outlet pipe 54. According to an example, the centrifugal pump may be an adaptive pump 10A has a casing 62 (as shown i other figures) forming an adaptive volute 75 A. The pump outlet 66 is coupled to a valve arrangement 1220 VL; VH via the outlet pipe 54. The valve arrangement 1220 has a valve inlet 1222 (See fig. 36B) which may be connected to the pump outlet 66, and a first valve outlet 1224 (See fig. 36B) for delivery of a system delivery flow Yl 0, Q_OUTS of fluid to a fluid system 52. The fluid system 52 may inlcude various parts 40, 50, 56, as discussed elsewhere in this disclosure e.g. in relation to figure 34 and/or 1 A and/or IB.

The example system 1210 may comprise a sensor 70 for generating a measuring signal SEA indicative of a fluid pressure pulsation PFP in the fluid 30. The measuring signal SEA may be delivered to the apparatus 150A as discussed e.g. in relation to figure 5, 15A, 15B or 23. Alternatively, the measuring signal SEA may be delivered to a pump location communications device 790, 790B for enabling remote monitoring and/or remote control as discussed in relation to figures 27-29. The example system 1210 may also comprise a device 170, 180 for generating a reference signal indicative of a rotational reference position of a rotating impeller 20.

The apparatus 150 A is configured to generate, based on said measuring signal and said reference signal, data indicative of the internal state X of the pump. The internal state data may comprise one or several values XI; X2; X3; X4. The internal state data may include a phase value FI, also referred to as XI . The phase value FI, XI is indicative of a current operating point 205, 550, 550(r) of the pump in relation to a Best Efficiency Point of operation.

The example system 1210 may also comprise a control module 150B configured to generate at least one set point parameter U I SP, U2SP based on said phase value (FI, FI(r), Xl(r)). The control module 150B may include a regulator 755 configured to generate the at least one set point parameter U 1 SP, U2SP based on said phase value FI(r), XI (r), as illustrated in figure 36A, and based on a desired phase value FIREFO-), XlREF(r), as illustrated in figure 36A. Thus, the desired phase value FlREF(r), X IREFW may constitute a desired operating point value XI REF, 205 REF which may be settable by an operator 230 via a user interface as disclosed in relation to other figures in this disclosure such as e.g. in figure 33, 39, and/or figure 40. The regulator 755 may be configured as disclosed in relation to any of the other figures in this disclosure. The at least one set point parameter UI SP, U2SP may comprise a rotation speed set point value UISP, FROTSP for controlling a rotational speed Ul , FROT of the impeller 20.

Referring to figures 34 and 37 an example of correlation between pulsation amplitude Y3 in the fluid system 52 and internal state X in the pump 10 is explained. More specifically, figure 37 illustrates a correlation between pulsation amplitude Y3 in the fluid system 52 and the rotation speed X3 of the impeller in the pump 10.

Figure 37 is a plot of a large number of successive pairs 1 165 of vector values X3 and Y3 ( See right hand side of figure 34 part 2). In figure 37, each dot represents a pair of values X3- Y3. A high density of dots indicates that the pump operated very often at that speed of rotation.

It can be seen that the rotation speed X3 = 900 RPM corresponds to a minimum detected vibration amplitude Y3 at 0,03 mm/s. The density of black dots is lower at rotational speeds X3 above about 950 RPM, indicating that the pump operated less often at rotational speeds X3 above about 950 RPM.

Referring to figure 34, the correlation data generator 1 160 may be configured to perform a regression analysis, also referred to as correlation analysis, based on received pairs 1 165 of values X3 and Y3 as illustrated in figure 37.

The regression analysis may, for example, employ linear regression. The linear regression analysis, when applied to a single dependent variable Y3 and a single independent variable, such as X3 or X2 or XI , will operate to identify a linear relation, i.e. a line, 1 180 that most closely fits the data according to a specific mathematical criterion. For example, the method of ordinary least squares computes the unique line 1 180 that minimizes the sum of squared differences between the true data and that line. Thus, the line 1 180 in figure 37 is an illustration of a result of linear regression based on received pairs of values X3-Y3. as discussed above. As illustrated in figure 37, the correlation may identify more than one line I 180. Figure 37 illustrates a line 1 180L for a span of speed values lower than 900 RPM. and a line 1 180H for a span of speed values higher than 900 RPM. In the example of figure 37, the detected amplitudes Y3 in the system 52 (See sensor 70Y and measured signal SEAYS signal in figure 34) have a minimum amplitude at about 900 RPM.

The linear regression analysis, may also be applied to the single dependent variable Y3 and to the single independent variable XI so as to, also between the variables XI and Y3, identify a linear relation. It is noted that the single independent variable XI is indicative of the operating point 205 of the pump 10, and the single dependent variable Y3 is indicative of a pulsation amplitude Y3 in the fluid system 52.

Referring to figure 34, the correlation data set 1 170, generated by correlator 150C1, may include a table of data or alternatively a linear equation. The linear equation for a line in a two- dimensional space, such as the two-dimensional space X1-Y3, can be established from points that the line passes. For example, when a line passes through two points (X1 A,Y3A) and (X 1 B,Y3B), then the symmetric equation for that line is given by equation 8.3:

wherein XlA and Y3A are the numerical values defining one point in the two- dimensional space X1-Y3, and

XI B and Y3B are the numerical values defining another point in the two-dimensional space X1-Y3.

Thus, equation 8.3 defines the linear correlation between the internal state parameter X I and the output parameter Y3 at an operating point of the centrifugal pump (See figure 38). As the skillled reader of this disclosure appreciates, the above equation 8.3 can be written either in the form

Y3 = f(Xl) (eq. 8.4) or in the form

Xl = f(Y3) (eq. 8.5)

The above equation 8.4 corresponds to matrix equation 8.2 discussed above for the multivariable case where the output state Y is experessed as a function of the internal pump state X. The above equation 8.5 allows a desired pulsation amplitude Y3REF to be expressed in terms of the corresponding temporal relation value XI, wherein the corresponding temporal relation value XI indicates the corresponding operation point 205:

XIREF - f (Y3REF) (eq. 8.6)

Figure 38 is an example plot of a generated linear regression result. Thus, the plot of figure 38 shows the identified line 1 180 that illustrates a relation between XI and Y3, at least when that pump operates at Operating Points of 0 < X 1 < 80 degrees. Thus, the correlation data generator 1 160 may deliver correlation data 1 170 indicative of the linear relation 1 180 when the linear regression analysis was applied to a single dependent variable Y3 and a single independent variable, such as X 1 .

With reference to figure 34, the correlation data set 1 170, generated by correlator 150C1 may be delivered to an internal state reference value generator 150c2.

The internal state reference value generator 150c2 may be configured to use the received correlation data 1 170 for transforming a desired value YREF into a corresponding internal state reference value XREF. Table 8 is an illustration of an example of a data transformation table for transforming a desired value Y3REF into a corresponding internal state reference value XI REF. Thus, a transformation, like table 8 may be created and used by correlator 150C1 and internal state reference value generator 150c2. The content of table 8 may be based on data such the example information in table 7 above.

Table 8: A correlation data set 1170 in the form of a correlation table for transforming a desired fluid system property Y3REF into an internal state parameter reference value X IREF

The example correlation data table 1 170, an example of which is illustrated by table 8, may indicate a correlation between internal status parameter value XI, indicative of a operating point, and output parameter Y3, indicative of a pulsation amplitude detected in the fluid system 52.

Based on equation 8.3 above and any two points (XI, Y3) or (XIREF, Y3REF) from the correlation data set 1170, an linear equation defining the correlation may be generated. Expressing the dependent variable Y3 as a function of the independent variable XI, the line 1180 in figure 38 may be described by rewriting equation 8.3 into equation 9:

Y3 = (Y3B - Y3A) / (X1B - X1A) * X1 - (Y3B - Y3A) / (X1_B - X1A) * X1A + Y3A (Eq. 9)

With reference to figure 38, the illustrated linear relation example 1 180 comprises the two points: (Xl_A, Y3_A) and (X1_B, Y3_B).

If these points had the following numerical values

(XI _A, Y3A) = (40, 200), and

(XIB, Y3_B) = (47, 220) then an equation as shown below would be achieved. By insertion of the above example values in equation 9 and expressing a dependent variable Y3 as a function of the independent variable XI, the line 1180, such as a line like the one in figure 38, may be described by the equation:

As mentioned above in connection with figure 34, the correlation data generator 1160 generates a correlation data set 1170. The correlation data set 1170 may be delivered in the form of a linear equation 1170 for transforming a desired state value YREF into a corresponding internal state reference state value XREF. Again with reference to figure 38 and the above illustrated linear relation example 1180 comprising the two points:

it is to be understood that equation 8.3 above may be re-written into equation 10 (below) so as to express a desired internal state value, i.e. an internal state reference value XIREF, as a function of the desired value Y3REF:

Accordingly, with reference to figure 34, the correlation data generator 1160 may generate the correlation data set 1170 in the form of a linear equation 1170 for transforming a desired value YREF into a corresponding internal state reference value XREF, and the linear equation 1170 may, for example be as shown by equation 10 above. Thus, equation 10 is an example of a correlation data set 1170. It is to be understood that correlation data 1170 may be provided in different forms, including e.g. as

- an equation 1170 expressing a desired internal state XIREF as a function of a desired system state YREF, and/or as

- a table 1 170 expressing a desired internal state XIREF as a function of a desired system state YREF.

A more complex case of a multi-variable monitoring system

Figures 37 and 38 serve as illustration of the function of the correlation data generator 1160 in the relatively simple case of regression analysis applied to a single dependent variable Y3 and a single independent variable XI or X3. However, is also an object to be addressed by solutions and examples disclosed in this document, to describe methods and systems for improved monitoring and/or control of an internal state X in a centrifugal pump 10 during operation. When the centrifugal pump 10 runs at a variable speed of rotation X3 = U1 and it also exhibits variations in operating point XI, the above described regression analysis as applied to a single dependent variable Y2 and a single independent variable XI may not suffice. In order to address this problem, however, the correlation data generator 1160 may apply regression analysis to a number of data pairs 1165 comprising a received internal state vector X(t) of dimension m and a received corresponding output vector Y(t) of dimension n, wherein m and n are positive integers.

Thus, when m status parameter values XI, X2, X3,..., Xm are to be correlated with n system parameter values Yl, Y2, Y3, ... Yn, the correlation data generator 1160 may be configured to generate a correlation data 1170 set by performing correlation of a received internal state vector X(t) and a received corresponding output vector Y(t) wherein

Accordingly, in this case the correlation data generator 1160 may be configured to perform a regression analysis so as to identify a more complex linear combination (i.e. more complex than a line in a two-dimensional space) that most closely fits the data according to a specific mathematical criterion. For example, the correlation data generator 1160 may perform a method of ordinary least squares, applied to a number of received vectors X(t) of dimension m and a number of received corresponding output vectors Y(t) of dimension n, so as to compute a unique hyperplane that minimizes the sum of squared differences between the received data and that hyperplane.

Accordingly, the correlation data generator 1160, when receiving vectors X(t) of dimension m and a number of received corresponding output vectors Y(t) of dimension n, is configured to generate a multi-dimensional correlation data set 1170. According to an example, the multi- dimensional correlation data set 1 170 may be delivered as data 1 170 indicative of the above mentioned hyperplane.

Alternatively, the multi-dimensional correlation data set 1 170 may be delivered as data 1 170 indicative of the coefficient matrix C, as discussed in relation to equation 8.2 above.

According to another example, the correlation data set 1 170 may include a table with values for pump parameter values XI ...Xm and corresponding system parameter values Yl...Yn, as discussed e.g in connection with table 8 above. In this context the values in the table may be based on a regression analysis such that the correlation table provides for a certain system state Y, defined by a detected combination of system parameter values Yl ...Yn, a set of pump parameter values XI ...Xm wherein each pump parameter value is an average of detected pump parameter values for the certain system state Y. Alternatively, the values in the table may be based on a regression analysis such that the correlation table provides for a certain pump state X, defined by a detected combination of pump parameter values XI ...Xm, a set of system parameter values Y1 ...Yn wherein each pump parameter value is an average of detected system parameter values for the certain pump state X.

According to an example, correlation data generator 1 160 may be configured to include Kalman filtering, also known as linear quadratic estimation (LQE), when generating a correlation data set 1 170.

This correlation solution advantageously enables identification and/or determination of a cause and effect relationship between the internal state X of the pump 10 and the a state Y of the fluid system 52, such as at least one system parameter measurement value Y3.

Moreover, this solution advantageously enables identification and/or determination of a cause and effect relationship between operating point 205, XI of the pump 10 and the fluid system state Y. Moreover, this solution advantageously enables identification and/or determination of a cause and effect relationship between the internal state X of the pump 10 and the fluid system state Y. As discussed above the internal state X may comprise one or more of the parameters XI, X2, X3, X4. The fluid system state Y may also be referred to as the product material state Y. The fluid system state Y may comprise one or more of the parameters Y 1 , Y2, ...Y10, as discussed above. This solution is versatile in that it allows for the defining of a desired fluid system state YREF, and for testing of alternative internal states, also referred to as operating points XOP, of the pumping process in order to search and identify an internal state XBEP of the pumping process that causes, or produces, the desired fluid system state YREF or that causes or produces a fluid system state Y as near as possible to the desired fluid system state YREF. Such an internal state may be referred to as a Best Operating Point, BEP. The values of the parameters at BEP may collectively be referred to as internal state BEP vector XBEP.

Moreover, the recording of a detected momentary pumping process internal state X(r) in association with a corresponding momentary fluid system state Y(r), produces correlation data indicative of a correlation between a momentary pumping process internal state X(r) and a corresponding momentary fluid system state Y(r).

By performing repeated recording of a number of mutually different detected momentary pumping process internal states X(r) in association with momentary fluid system states Y(r) that were caused by the respective momentary pumping process internal states X(r), wherein r is a number variable indicative of a number of different points in time, a correlation data set may be produced. Such a correlation data set is indicative of a correlation between a number of momentary pumping process internal states X(r) and a number of corresponding momentary fluid system states Y(r).

Referring again to figure 34, the internal state reference value generator 150c2 may be configured to use the received correlation data 1 170 for transforming a desired value YREF into a corresponding internal state reference value XREF.

In this connection it is noted that there may also be a linear relation between a single dependent variable such as the fluid system pulsation Y3 on the one hand, and on the other hand two independent variables, such as the operating point value, at least when the operating point value XI is varied within as certain range of operating point values, and the rotational speed X3, f_ROT of the impeller 20. In such a case the linear relation 1170 may be expressed by the equation of a plane in a three- dimensional space. Accordingly, with reference to figure 34, the correlation data generator 1160 may generate the correlation data set 1170 in the form of the equation of a plane in a three-dimensional space. The equation of a plane in a three-dimensional space, such as the space (X3, XI, Y3) can be expressed as equation 11 :

The equation of a plane written in the form of equation 11 is called a linear equation in three- dimensional space.

Generating internal state reference values by solving a matrix equation

As mentioned above, the output vector Y(r) depends, at a selected operating point, on the internal state vector X(r) in accordance with a linear model:

wherein C is a coefficient matrix.

With reference to figure 34 it is to be understood that the internal state reference value generator 150c2 may be configured to solve equation 8.2 by matrix inversion. In this context reference is made to the book Essential Mathematics for Economic Analysis, Fourth Edition, ISBN 978-0-273-76068-9, and in particular to chapter 15 relating to “Matrix and Vector Algebra”, and chapter 16 relating to “Determinants and Inverse Matrices”, the content of which is hereby incorporated by reference. Equation 8.2 above is a matrix equation, i.e. a condensed manner of expressing a system of several equations. When these equations are all linear, the study of such systems belongs to an area of mathematics called linear algebra. Even if the equations are non-linear, it is possible to make a linear approximation of these equations around a selected operating point, as mentioned above. Equation 8.2 above may be an example of such a a linear approximation that will be valid around a selected operating point XOP, 205, 550. Thus, the internal state reference value generator 150c2 may be configured to solve equation 8.2 by matrix inversion.

Provided that the determinant of the coefficient matrix C is not zero, it is possible to calculate the inverse of the coefficient matrix C. The inverse of the coefficient matrix C is denoted C'¹. Thus, the internal state reference value generator 150c2 may be configured to use the received correlation data 1170 in the form of the above matrix equation 8.2 for transforming a desired vector YREF into a corresponding internal state reference vector XREF. This may be achieved e.g. by calculating values for the coefficients in matrix C, and solving the matrix equation 8.2. As discussed above, in connection with equation 8.2, the values for the coefficients in matrix C may be constants. The constant values for the coefficients in matrix C may be set to the derivatives C = dY/dX at the selected operating point XOP, 205, 550.

In a next step of solving the above matrix equation 8.2, each side of equation 8.2 is multiplied from the left by C'¹ :

Thus, the solution to equation 8.2 is

Accordingly, the internal state reference value generator 150c2 may be configured to express a desired internal state XREF, i.e. an internal state reference vector XREF, as a function of the desired output vector YREF according to matrix equation 10.4 below:

Thus, with reference to figure 34 part 1, the internal state reference value generator 150c2 may be configured to receive a desired output vector YREF, and, using equation 10.4, the internal state reference value generator 150c2 may be configured to generate a corresponding desired internal state vector XREF-

Use of the correlation data for operating a pump

With reference to figure 34, an operator 230 in the control room 220 is tasked with operation of the centrifugal pump 10. The operator may use regulator 1190 for operating the pump 10. The regulator 1190 is coupled to the user interface 210, 210B also referred to as Human Computer Interface (HCI) 210B, as shown in figure 34.

The example control room 220, shown in figure 34, includes an internal state control system 1200 comprising the internal state reference value generator 150c2 and the user interface 210, 210B and regulator 755C or regulator 240C. The internal state control system 1200 may be configured to perform the following steps: (Step S3000:) cause the user interface 210 to convey information requesting the operator to provide user input indicative of a desired fluid system state YREF. The user input indicative of a desired fluid system state YREF may be indicative of at least one desired system parameter measurement value, such as Y9 and/or Y 10, as discussed above. For example, the user input may be indicative of a desired fluid system pressure Y9REF, P54S_REF, and/or desired fluid system flow Y10REF, QOUTSREF (See figure 34 and/or figure 36A in conjunction with figure 39 and/or figure 40).

This request, S3000, may be generated by software included in the regulator 755C, or by software included in the regulator 240C, or by software included in the internal state reference value generator 150c2.

The internal state control system 1200 may also be configured to:

(Step S3005:) receive, e.g. via user interface 210, data indicative of a desired fluid system state YREF and/or desired fluid system pressure Y9REF, P54S REF and/or desired fluid system flow Y10REF, QOUTSREF

Moreover, the internal state control system 1200 may be configured to perform a method comprising the following steps:

S3010: generate a operating point reference value (XIREF; FIREF) based on said data indicative of said desired fluid system state YREF and/or said desired fluid system pressure Y9, P54S (Y2REF) and/or desired fluid system flow Y10REF, QOUTSREF, and a correlation data set (1170); said correlation data set (1170) being indicative of a causal relationship between a certain operating point value (Xl(r), FI(r), TD, R?(r) ) and a corresponding certain fluid system pressure Y9, P54S, at said speed of impeller rotation (U 1 , fRor); and/or indicative of a causal relationship between a certain internal state XREF and a corresponding certain fluid system state YREF- The corresponding certain fluid system state YREF may include a certain desired fluid system flow Y10REF, QOUTSREF.

The step S3010 may involve the delivery of the received data, from the user interface 210 to the internal state reference value generator 150c2 (See figure 34 and/or figure 35 and/or figure 39).

Thus, the internal state reference value generator 150C, 150c2 is configured to transform data relating to desired fluid system state YREF into data indicative of a corresponding desired internal state XREF and/or data indicative of a corresponding desired operating point reference value XIREF (r), FIREF (r), as discussed above.

According to an example, the transformation of data relating to desired fluid system state YREF into data indicative of a corresponding desired internal state XREF may include the following steps.

When the operator has fed in values indicative of the desired fluid system state YREF, the internal state reference value generator 150C, 150c2 is configured to

51) read the current internal state X(r), i.e. the parameter values XI, X2, X3,... Xn provided by status parameter extractor 450.

52) Select the coefficient matrix C'¹ having coefficient values related to the current internal state X(r), i.e. the coefficient matrix C'¹ having coefficient values related to the parameter values XI, X2, X3,... Xn provided by status parameter extractor 450.

53) calculate a desired internal state XREF, i.e. an internal state reference vector XREF, as a function of the desired output vector YREF according to matrix equation 10.4:

using the coefficient matrix C ' selected in the previous step.

54) generate set point values U for the pump 10, 10A, 10D based on reference values corresponding to the calculated a desired internal state XREF. The set point values U may be generated as discussed e.g. in connection with control module 150B in figure 26 in this disclosure.

55) Run the pump 10, 10A, 10D with the generated set point values U as control parameters for operating the pump.

56) repeat the above steps SI to S5 in an iterative manner. System for monitoring and providing improved pumping process information content to an

Figure 39 is a block diagram of the system 1130 for monitoring of an internal state X of a pump 10 and for providing improved information content to an operator 230 of the pump 10. The system illustrated in Figure 39 also enables the provision of a method for monitoring and/or operating a fluid system 52 coupled to a centrifugal pump 10; 10A; 10D. The centrifugal pump 10; 10A; 10D may have a casing 62 forming a volute 75 in which a rotatable impeller 20, having a first number of vanes 310, is disposed for urging a fluid 30 via the volute to a pump outlet 66, 54 for delivery to the fluid system 52.

In Figure 39 the system 1130 is shown as a block diagram including a centrifugal pump illustrated as a box 10 receiving a number of inputs Ul, ... Uk, and generating a number of outputs Yl, ... Yn. Thus, in terms of signal processing and analysis, the pump 10 receives an input vector U comprising one or more set point parameter values UI SP, U2SP thereby influencing an internal state X of the pump 10; 10A; 10D and/or pumping process. The internal state X may have a causal affect on an internal state Y of the fluid system 52. In this connection it is noted that the fluid system internal state Y relates to pressure and/or flow of fluid 30 in said fluid system 52. The internal state Y of the fluid system 52 may be indicated by one or more fluid system parameters Yl, ... Yn, also referred to as outputs Yl, ... Yn.. The one or more fluid system parameters Yl, ... Yn may be collectively referred to as an output vector Y, in the manner discussed elsewhere in this document.

The system 1130 of figure 39 may include parts, and be configured, as described above in relation to figure 1 A and/or figure IB and/or as described in any of the other examples described in this disclosure, e.g. in relation to figures 1-38. Thus, the system 1 130 may include a centrifugal pump 10, as discussed in connection with figures 34 to 38 above and/or as discussed in relation to figures 1-38.

The system 1130 includes a Monitoring Module 150A and/or a Correlation Module 150C, as shown in fig. 39. The Correlation Module 150C may operate to generate the correlation data set 1170 during operation of the pump 10, as described above, and/or Correlation Module 150C may operate to transform data relating to desired fluid system state YREF into data indicative of a corresponding desired internal state XREF, the transformation step being based on a correlation data set 1 170 that is relevant for the pump 10 being operated.

The system 1 130 shown in figure 39, includes an internal state control system 1200 comprising the internal state reference value generator 150c2 and the user interface 210, 210B and regulator 240C.

The internal state control system 1200 may be configured to perform the following steps: (Step S3000:) cause the user interface 210 to convey information requesting the operator to provide user input indicative of a desired fluid system state YREF. The user input indicative of a desired fluid system state YREF may be indicative of at least one desired system parameter measurement value, such as Y1 and/or Y2 and/or Y9, and/or Y10, as discussed above. For example, the user input may be indicative of a desired fluid system pressure Y9REF, P54S_REF, and/or desired fluid system flow Y10REF, QOUTSREF.

This request, S3000, may be generated by software included in the regulator 240C.

The internal state control system 1200 may also be configured to:

S3010: generate a corresponding desired internal state XREF (also referred to as internal state reference vector XREF) which may include a operating point reference value (XI REF; FIREF). The internal state reference vector XREF may be based on said data indicative of said desired fluid system state YREF and/or said desired fluid system pressure Y9, P54S (Y2REF) and/or desired fluid system flow Y10REF, QOUTSREF, and a correlation data set (1170); said correlation data set (1170) being indicative of a causal relationship between a certain internal state XREF and a corresponding certain fluid system state YREF- The step S3010 tnay involve the delivery of the received data (i.e. indicative of a desired fluid system state YREF), from the user interface 210 to the Correlation Module 150C (See figure 39).

The Correlation Module 150C may include an internal state reference value generator 150c2 configured to transform data relating to desired fluid system state YREF into data indicative of a corresponding desired internal state XREF and/or data indicative of a corresponding desired operating point reference value XIREF (r), FIREF (r), as discussed above.

System for Monitoring Pump Product and providing improved Process Control

Figure 40 is a block diagram of a system 11308 for monitoring of an internal state X of a pump 10 and for enabling improved control of a pumping process that occurs in a pump 10. The system 11308 may include some, or all, of the features discussed in connection with figure 39. Thus, the system 1130B may include some, or all, of the features of system 1130 of figure 39. Thus, the system illustrated in Figure 40 enables the provision of a method for monitoring and/or operating a fluid system 52 coupled to a centrifugal pump 10; 10A; 10D. The centrifugal pump 10; 10A; 10D may have a casing 62 forming a volute 75 in which a rotatable impeller 20, having a first number of vanes 310, is disposed for urging a fluid 30 via the volute to a pump outlet 66, 54 for delivery to the fluid system 52.

The system 1 130, 1130B of figure 40 may include parts, and be configured, as described above in relation to figure 1 A and/or figure IB and/or as described in any of the other examples described in this disclosure, e.g. in relation to figures 1-39. Thus, the system 1130 may include a centrifugal pump 10, as discussed in connection with figures 34 to 39 above and/or as discussed in relation to figures 1-39.

The system 1130B includes a Correlation Module 150C, as shown in fig. 40, and system 1130B may also include a Monitoring Module 150A.

The Correlation Module 150C may operate to generate the correlation data set 1170 during operation of the pump 10, as described above, and/or Correlation Module 150C may operate to transform data relating to desired fluid system state YREF into data indicative of a corresponding desired internal state XREF, the transformation step being based on a correlation data set 1170 that is relevant for the pump 10 being operated.

The system 1130 shown in figure 39, includes an internal state control system 1200 comprising the internal state reference value generator 150c2 and the user interface 210, 210B and regulator 240C.

The system 1 130B may be configured to perform the following steps:

(Step S3000:) cause the user interface 210 to convey information requesting the operator to provide user input indicative of a desired fluid system state YREF. The user input indicative of a desired fluid system state YREF may be indicative of at least one desired system parameter measurement value, such as Y1 and/or Y2, as discussed above. For example, the user input may be indicative of a desired fluid system pressure Y9REF, P54S REF, and/or desired fluid system flow Y10REF, QOUTSREF.

This request, S3000, may be generated by software included in the regulator 150B, or by software included in the Correlation Module 150C, or by internal state control system 1200.

The system 1 130B may also be configured to:

(Step S3OO5:) receive, e.g. via user interface 210, data indicative of a desired fluid system state YREF .

Moreover, the system 1 130B may be configured to perform a method comprising the following steps:

S3010: generate a corresponding desired internal state XREF, also referred to as internal state reference vector XREF, which may include a operating point reference value XI REF; FIREF. The internal state reference vector XREF may be based on said data indicative of said desired fluid system state YREF and/or said desired fluid system pressure Y9, P54S (Y2REF), and a correlation data set (1 170); said correlation data set (1170) being indicative of a causal relationship between a certain internal state XREF and a corresponding certain fluid system state YREF. The corresponding certain fluid system state YREF may include a certain desired fluid system flow YI OREF, Q_OUTSREF-

The step S3005 may involve the delivery of the received data (i.e. indicative of a desired fluid system state YREF), from the user interface 210 to the Correlation Module 150C (See figure 40).

The Correlation Module 150C may include an internal state reference value generator 150c2 configured to transform data relating to desired fluid system state Y EF into data indicative of a corresponding desired internal state XREF and/or data indicative of a corresponding desired operating point reference value XI REF (r), FIREF (r), as discussed above.

Moreover, the system 1 130B may be configured to perform a method comprising the following steps: controlling via a regulator 755C, 755 said fluid system state (Y) based on said at least one status parameter reference value (XI REF; FIREF) included in an internal state reference vector XREF, at least one status parameter value (XI, X2, X3, X4, X5, X6, X7 ) or an internal state vector (X) including said at least one status parameter value indicative of a current internal state (X) of the pumping process, and at least one status parameter error value (XIERR, X2ERR, X3ERR, X4ERR, X5ERR, X6ERR, X7ERR) or an internal state error vector X ERR including said at least one status parameter error value, wherein said at least one status parameter error value (X I ERR, X2ERR, X3ERR, X4ERR, X5ERR, X6ERR, X7ERR) depends on said at least one status parameter reference value (XI REF; FIREF), and said at least one status parameter value (XI, X2, X3, X4, X5, X6, X7 ).

Moreover, the system 1 BOB may be configured to perform a method comprising the following steps: controlling via a regulator 755C, 755 said fluid system state (Y) based on an internal state reference vector XREF indicative of a current internal state (X) of the pumping process, and an internal state vector (X) indicative of a current internal state (X) of the pumping process, and an internal state error vector X ERR including at least one status parameter error value, wherein said internal state error vector X ERR depends on said internal state reference vector XREF, and said internal state vector (X).

Moreover, the system 1130B may be configured to perform a method comprising the following steps: controlling, by a regulator 150B, a volute set point value (U2SP) in dependence on an operating point reference value (FIREF(T) ), and wherein said volute is an adaptive volute (75) having an adjustable cross-sectional area and/or adjustable volume, and wherein said volute set point value (U2SP; VPSP) controls said adjustable volute volume.

Any individual step of the methods disclosed could be carried out or reiterated simultaneously to another individual step or steps of the method, unless it would involve a logical contradiction. In continuous operation of the centrifugal pump, the steps are typically reiterated continuously, such as sequentially in a loop. Although actions defined in this method are typically performed as such steps, they could be carried out according to this disclosure as actions in a more general sense than steps.

Natural frequency and fluid system pulsation maxima

A problem that may occur in a fluid system 52 is that when an operator has set the pump at a certain impeller rotational speed X3, fROT for obtaining a desired flow Y2 from the pump outlet 66, that also means that a corresponding certain vane pass frequency X4 is obtained. With reference to figure 34 and/or figure 39 and/or figure 40 in conjunction with figures 1 A and/or IB, it is noted that the fluid system 52, or a part of the fluid system, may exhibit a natural frequency, also referred to as eigenfrequency. The natural frequency of a fluid system is the frequency at which a system tends to oscillate. If the oscillation of the fluid system 52 is driven by an external force, such as pulsation PFP, originating from the pump 10, and that pulsation PFP has a frequency X4, fp which is close to a natural frequency of the fluid system, this frequency is called resonant frequency.

Resonance is a phenomenon that occurs when a fluid system is subjected to a vibration or pulsation having a frequency that matches the natural frequency of the fluid system 52. The resonant frequencies of a fluid system 52 can be identified when the pulsation amplitude Y3 and or Y6 in the fluid system 52 exhibits an amplitude that is a relative maximum. This may be achieved by generating a parameter value Y 1 1 which is indicative of a relation between the first fluid system pulsation amplitude value Y3 and the pulsation amplitude X2. According to an example the relation Y1 1 may be generated by dividing the first fluid system parameter value Y3 by the pump internal state parameter value X2, i.e.

Yl l = Y3/X2

The amplitude relation value Yl l is of interest as a system parameter value since the first fluid system pulsation amplitude value Y3 has a repetition frequency Y4 that equals the vane pass frequency X4 of the pump 10. The frequency X4 is the frequency of the pulsation amplitude X2. Thus, when the vane pass frequency X4 is close to a natural frequency of the fluid system, then the amplitude X2 of the pulsation originating in the volute of the pump may cause the fluid system to resonate, rendering amplification of the first fluid system pulsation amplitude value Y3.

Avoidance of resonance by correlation and pump control

The inventor concluded that a resonance frequency fR RES of the fluid system 52 may be identified e.g. by means of correlation of the vane pass frequency X4 and the amplitude relation value Yl l .

When the a resonance frequency fR RES of the fluid system 52 has been detected, information can be provided to an operator 230 (see e.g. figures 39 and 40) about the rotational speed values X3 fROT that correspond to the fluid system resonance frequency fR RES SO that the pump may be operated at impeller rotational speed values X3 TROT that deviate from the impeller rotational speed values X3 FROT that cause resonance.

Advantageously, the pump 10 may be associated with a valve arrangement, e.g. as discussed in connection with figure 36A so as to enable the provision of a desired system flow Y10, Q_OUTS while allowing the pump 10 to run at impeller rotational speed values X3 FROT that deviate From the impeller rotational speed values X3 FROT that cause resonance.

Alternatively, it is noted that the provision oF an adaptive pump 10A having an adaptive volute, as discussed in connection with figures 24 to 29 advantageously enables the provision of a desired system Flow Y2, QOUT while allowing the pump 10 to run at impeller rotational speed values X3 FROT that deviate From the impeller rotational speed values X3 FROT that cause resonance.

Figure 41 is a graph illustrating an example oF the dependence oF an amplitude relation value Y1 1 oF the vane pass Frequency X4. Thus the graph in figure 41 may be an illustration of correlation data 1 170 indicating a causal effect between the vane pass frequency X4 of the pump 10 and the amplitude relation Y1 1.

As mentioned above, under the heading “Natural frequency and fluid system pulsation maxima“ the resonant frequencies of a fluid system 52 can be identified when the pulsation amplitude Y3 in the fluid system 52 has an amplitude that exhibits a relative maximum. This may be achieved by generating a parameter value Y1 1 which is indicative of a relation between the first fluid system pulsation amplitude value Y3 and the pulsation amplitude X2. Both of these amplitude values relate to the vane pass frequency X4 of the pump 10.

Accordingly, correlation data 1 170 may be created for indicating a causal effect between the vane pass frequency X4 of the pump 10 and the amplitude relation Y1 1 . The correlation data 1170 may be provided in many alternative forms, as discussed elsewhere in this disclosure, e.g. in connection with table 8 in this disclosure.

Thus, correlation data 1 170 may be created, e.g. based on a regression analysis as discussed in connection with figure 34, for the purpose of detecting resonance in the fluid system 52. Hence, resonance in the fluid system 52 may be detected e.g. by a method as discussed below. Moreover, resonance in the fluid system 52, when caused by the pulsation amplitude X2 originating in the pump 10 may also be avoided e.g. by a method as discussed below.

Accordingly, for the purpose of detecting fluid system parameter values, it is desirable to analyse the fluid system 52, e.g. by one or more sensors 70Y (See Fig. 34 and/or 36A) coupled to one or more analysers 150AY (See Fig 34). Thus, the one or more analysers 150AY may be configured to generate at least one fluid system parameter value Yl, Y2, Y3, ... Yn based on said analysis. The at least one fluid system parameter value Yl, Y2, Y3, ... Yn is/are indicative of an internal state Y of the fluid system. Thus, the at least one fluid system parameter value Yl, Y2, Y3, ... Yn may be indicative of an internal state Y of the fluid system in terms of pressure and/or flow of fluid 30 in the fluid system 52.

Moreover, it is desirable to generate pump status data XI ; X2; X3; X4; Xm indicative of an internal state X of the centrifugal pump. Such pump status data may include at least one pump status parameter value XI ; X2; X3; X4; Xm.

Referring to figure 34, the method may further comprise: performing, by a correlator 150C; 150C1, 150C2, 150C3 (See e.g. Figures 34, 39, 40), a correlation between the at least one pump status parameter value XI ; X2; X3; X4; Xm, and the at least one fluid system parameter value Yl, Y2, Y3, ... Yn so as to generate correlation data 1 170, 1 180 indicative of a causal relationship between the at least one pump status parameter value XI ; X2; X3; X4; Xm; and the at least one fluid system parameter value Yl, Y2, Y3, ... Yn.

According to an example, an individual pump status parameter value (XI ; X2; X3; X4; Xm) is indicative of an aspect of the internal state (X) of the pump (10), and an individual fluid system parameter value (Yl, Y2, Y3, ... Yn) is indicative of an aspect of the internal state (Y) in said fluid system (52, 40, 50, 56).

According to an example, the method further comprises receiving at least one fluid system parameter reference value (Y I REF, Y2REF, Y3REF, ... YHREF ) indicative of a desired fluid system internal state (YREF); and generating at least one pump status parameter reference value (XI REF, X2REF,

X3REF, X4REF, XHIREF); wherein said at least one pump status parameter reference value (XI REF, X2REF, X3REF,

X4REF, XHIREF) is generated based on said system reference data (YI REF, Y2REF, Y3REF, ... YHREF ), and correlation data (1170, 1180) indicative of a causal relationship between said at least one pump status parameter reference value (XI REF, X2REF, X3REF, X4REF, XITIREF) and said at least one fluid system parameter reference value (Y I REF, Y2 EF, Y3REF, ... YOREF ).

According to an example, the correlation data (1170, 1180) is based on a regression analysis for identifying a linear relation that most closely, according to a mathematical criterion, fits a number of received pump status vectors (X(t)) of a first dimension (m) and a number of received corresponding fluid system vectors (Y(t)) of a second dimension (n), wherein said first dimension (m) is a positive integer larger than zero, and said second dimension (n) is a positive integer larger than zero.

When the dimension of a vector, such as a pump status vector X(t) or a fluid system vector Y(t) is larger than one (1) the matrix equations 8.2 and/or 10.4 discussed above in this disclosure, may be applicable. When the dimension of a vector, such as a pump status vector X(t) or a fluid system vector Y(t) is equal to one (1), reference may be made to equation 8.3 discussed above in this disclosure.

According to an example, the fluid system analysis includes generating a first amplitude relation value (Y11), wherein the first amplitude relation value Y11 is indicative of a relation between a first fluid system parameter value Y3 indicative of a first fluid system pulsation amplitude Y3, SPY having a first fluid system pulsation repetition frequency Y4 and a second pump parameter value X2, Sp indicative of an amplitude of the first fluid pressure pulsation PFP having a first repetition frequency fp. In thgis context, the first repetition frequency fR is a number of occurrences of a repeating event Sp per revolution of said pump impeller 20; and the first fluid system pulsation repetition frequency Y4 is equal to said first repetition frequency fp.

According to an example, with reference to figure 41 , the method further comprises identifying a local maximum Y1 Ipeak of said first amplitude relation value Y11, and identifying a certain repetition frequency value fR RES.

The certain repetition frequency value fR RES is a value of said first repetition frequency X4, fR that is associated with the local maximum Y1 Ipeak of said first amplitude relation value Y11. Hence, the certain repetition frequency value fp RES is indicative of a fluid system resonance frequency.

According to an example, with reference to figure 41 , the method further comprises identifying a range of vane pass frequencies X4, from a lower limit value X4RES_LOW to an upper limit value X4RES UP. These limit values may be identified based on a predetermined amplitude relation value Y1 ILIM (See Figure 41). Since the vane pass frequency X4 is equal to X3*L, wherein L is the number of vanes of the impeller, and X3 is the rotational speed of the impeller 20, the vane pass limit frequency values X4RES LOW and X4RES_UP can be translated into corresponding impeller speed limit values X3RES_LOW and X3RES_UP.

Thus, according to an example, with reference to figure 41, the method further comprises identifying a range of impeller speed values (X3, fpoT), said identified impeller speed range including a certain impeller speed value (X3RES, ROT RES) corresponding to said certain repetition frequency value (IR RES). Thus, the certain repetition frequency value (fp RES) may be indicative of a vane pass frequency X4, fp RES causing a local maximum of the relation value Y11. Thus, the vane pass frequency IR RES may be indicative of a natural frequency of the fluid system 52, since the system appears to exhibit resonance at the vane pass frequency X4 = f RES-

47. According to an example, with reference to figure 36A, the method further comprises controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52) and/or controlling another flow (QR), such as for example a return flow (QR), by providing set point values to a valve arrangement that comprises one or more flow control valves (VL; VH). The another flow QR is thus diverted from flowing to the fluid system 52.

Fluid system resonance may advantageously be avoided by controlling the impeller speed X3 as discussed below:

According to an example, with reference to figure 36A in conjunction with figure 39 or 40, the method further comprises receiving, e.g. via a user interface (210, 210S, 1200), information indicative of a desired system delivery flow (Y 1 OREF, Q_OUTS_REF) and/or information indicative of a desired system delivery pressure (Y9REF, PS4S_REF); generating, based on said received information indicative of a desired system delivery flow (YI OREF, Q_OUTS_REF) and/or information indicative of a desired system delivery pressure (Y9REF, P54S_REF), said rotation speed set point value (Ulsp, f_ROTSP) for controlling a rotational speed (Ul, f_ROT) of the impeller (20); comparing said rotation speed set point value (U 1 SP, f_ROTSP) with said identified impeller speed range; and when said comparison indicates that said rotation speed set point value (U 1 SP, f_ROTSP) corresponds to an impeller speed that is within said identified impeller speed range, i.e. the impeller speed range that is identified as causing resonance, then said rotation speed set point value (U I SP, f_ROTSP) is adjusted, e.g. by a control module (150B, 755) or by an operator 230, to a value that corresponds to an impeller speed that is outside of said identified impeller speed range.

When the rotation speed set point value (U l sp, fRoisp) is adjusted so as to increase the impeller speed f_ROT, X3, then the following actions are relevant:

Since the flow QOUT, Y2 is proportional to impeller speed FROT, X3, the rotation speed may be increased such that the vane pass frequency X4 exceeds the upper limit value X4RES UP (See Figure 41) rendering an increased pump flow QOUT, Y2. In this manner, this solution advantageously enables a change of the impeller speed f_ROT, X3 such that the impeller speed fROT, X3 becomes outside of the resonant impeller speed range. In figure 41 the resonant impeller speed range is indicated, in terms of vane pass frequency, from lower limit value X4RES.LOW to an upper limit value X4_RES UP-

When the pump is an adaptive pump 10A, as discussed e.g. in connection with figures 24-26 in this disclosure, then the set point value I sp may then be controlled and set so that the cross-sectional area of the volute 75A is increased so as to accomodate the increased pump flow QOUT, Y2 while maintaining BEP flow (based on the parameter XI) when said comparison indicates that said rotation speed set point value (U 1 SP, f_ROTSP) corresponds to an impeller speed that is within said identified, i.e. resonant, impeller speed range, and the impeller speed f_ROT, X3 is increased.

Alternatively, when the rotation speed set point value (UI SP, f_ROTSP) is adjusted so as to decrease the impeller speed f_ROT, X3, then the following actions are relevant:

Since the flow QOUT, Y2 is proportional to impeller speed IROT, X3, the rotation speed fROT, X3 may be decreased such that the vane pass frequency X4 becomes lower than the lower limit value X4RES LOW rendering a decreased pump flow QOUT, Y2.

In this manner, this solution advantageously enables a change of the impeller speed f_ROT, X3 such that the impeller speed fROT, X3 becomes outside of the resonant impeller speed range. In figure 41 the resonant impeller speed range is indicated, in terms of vane pass frequency, from lower limit value X4RES_LOW to an upper limit value X4R_ES UP.

When the pump is an adaptive pump IDA, as discussed e.g. in connection with figures 24-26 in this disclosure, then the set point value U2SP may then be controlled and set so that the cross-sectional area of the volute 75 A is decreased so as to accomodate the decreased pump flow QOUT, Y2 while maintaining BEP flow (based on the parameter XI) when said comparison indicates that said rotation speed set point value (U 1 SP, f_ROTSP) corresponds to an impeller speed that is within said identified, i.e. resonant, impeller speed range, and the impeller speed f_ROT, X3 is decreased.

Thus, as discussed above with reference to figure 41 in conjunction with figures 34 and figures 24-29 an adaptive pump 10a may be controlled to deliver a desired fluid system flow Y10 or a desired fluid system pressure Y9 while maintaining an operating point 205 at BEP, rendering high pump energy efficiency and minimized pulsation amplitudes X2. Minimized pulsation amplitudes X2 and high pump energy efficiency may also be attained by connecting the pump to and a valve arrangement (VL; VH) as discussed in connection with figure 36A and 36B, or as discussed in connection with figure 42, as explained below:

When the rotation speed set point value (U I SP, f_ROTSP) is adjusted so as to increase the impeller speed f_ROT, X3, and the pump outlet is coupled to a valve arrangement (VL; VH) as discussed in connection with figure 36A and 36B, or as discussed in connection with figure 42, then the following actions are relevant:

Since the flow QOUT, Y2 is proportional to impeller speed f_ROT, X3, the rotation speed may be increased such that the vane pass frequency X4 exceeds the upper limit value X4RES_UP (See Figure 41) rendering an increased pump flow QOUT, Y2. In this manner, this solution advantageously enables a change of the impeller speed f_R,_O X_T 3 such that the impeller speed fROT, X3 becomes outside of the resonant impeller speed range. In figure 41 the resonant impeller speed range is indicated, in terms of vane pass frequency, from lower limit value X4RES_LOW to an upper limit value X4RES_UP-

Thus, when the pump outlet 66 is coupled to a valve arrangement (VL; VH) as discussed in connection with figure 36A and 36B, or as discussed in connection with figure 42, and the rotation speed set point value (UI SP, f_ROTSP) is adjusted so as to increase the impeller speed fROT, X3, then at least one valve in said valve arrangement VL; VH (See figure 36A, 36B or 42) is adjusted so as to reduce the flow Y10 in relation to the another flow QR such that the system delivery flow is maintained at desired system delivery flow (Y I OREF, Q_OUTS_REF) while allowing the pump 10 to run at the higher impeller speed f_ROT, X3 such that the vane pass frequency is above the upper limit value X4RES UP.

According to an example, with reference to figures 36A and 36B or 42 in conjunction with figure 39 or 40, the method further comprises adjusting at least one valve in said valve arrangement (VL; VH) for controlling said system delivery flow (Y10, Q_OUTS) based on said adjusted rotation speed set point value (UI SP, f_ROTSP).

Figure 42 shows a schematic block diagram of yet another example of a process monitoring system. The example of figure 42 provides a similar effect, or same effect, as compared to the example system discussed in connection with figures 36A and 36B. The inventor, when looking at a number fluid systems 5 (Se figure 1 A) in industry with a pump connected 10 connected directly to the fluid system 52, observed that the pump 10 was oftentimes oversized, i.e. it was often operated at a lower speed of rotation TROT and at lower flow than BEP so as to provide the desired flow.

Thus, in view of an aspect of the state of the art, a problem to be addressed is how to enable delivery of a variable fluid flow and pressure while reducing or eliminating unfavourable centrifugal pump operating conditions. Thus, the inventor came up with the idea to provide a kit of parts for adapting such a system.

Such a kit of parts may comprise an apparatus (150, 150A, 450) for monitoring an internal state (X) of a centrifugal pump 10; 10A; a valve arrangement, a measurement sensor 70 for generating a measuring signal SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of fluid pressure pulsation PFP, P54, +, -; a device 170, 180 for generating a reference signal indicative of a rotational reference position of a rotating impeller 20 in the pump 10; control module 150B, 755 for controlling a rotational speed (Ul, fRo ) of the impeller 20; and for controlling the valve arrangement so as to control the system delivery flow Y10, Q_OUTS to the fluid system 52.

Referring to Figure 42, there is provided a system comprising: an apparatus (150, 150A, 450) for monitoring an internal state (X) of a centrifugal pump 10; 10A. The centrifugal pump 10; 10A may be as discussed in connection with any any of the figures 1 A to 41 in this disclosure. Thus the pump has a casing (62) forming a volute (75) in which a rotatable impeller (20), having a first number (L) of vanes (310), is disposed for urging a fluid (30) via the volute (75) to a pump outlet (66) for delivering a pump outlet flow (QOUT, Y2), thereby causing a fluid pressure pulsation (PEP, P54, +, -).

The system also comprises a valve arrangement (VL; VH ) having a valve inlet (1222) which is connectable to a pump outlet (66, 54), and a first valve outlet (66D) for delivery of a system delivery flow (Y10, Q_OUTS) of fluid to a fluid system (52, 40, 50, 56). The system also comprises a measurement sensor (70, 7O54, 70?7, 7078, 330, 350, 450) for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP, P54, +, -).

The system also comprises a device (170, 180, 330, 350, 450) for generating a reference signal indicative of a rotational reference position of a rotating impeller (20).

The apparatus (150, 150A, 450) is configured to detect, in said measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)), occurrences of a signal event signature (Sp(r); Sp) having an event repetition frequency (fa) that depends on said first number (L) when said first number (L) is higher than one. The apparatus (150, 150A, 450) is also configured to receive or generate, based on said reference signal (Ep, P(i), P(j), P(q)), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution such that a reference position signal value (Ps, Pc, 1, 1C) has a certain occurrence frequency (IR). said certain occurrence frequency (fp) being equal to said event repetition frequency (fp).

The apparatus (150, 150A, 450) is configured to generate, based on said measuring signal and said reference signal, data (XI; X2; X3; X4) indicative of said internal state (X) of the centrifugal pump (10); said internal state data (XI; X2; X3; X4) including a temporal relation value (XI, Xl(r), FI, FI(r)) based on a temporal relation between said repetitive signal event signature (Sp(r); Sp) occurrences and said repetitive reference position signal value (Ps, Pc, 1, 1C) occurrences.

It is noted thet the temporal relation value (XI, XI (r), FI, Fl(r)) may be indicative of a current operating point (205, 550, 550(r)) of the pump in relation to a Best Efficiency Point of operation.

The system also comprises a control module (150B, 755) configured to generate at least one set point parameter (UI SP, U2sp) based on said temporal relation value (XI, Xl(r), FI, FI(r)); wherein said at least one set point parameter (UI SP, U2SP) comprises a rotation speed set point value (UISP, f_ROTSP) for controlling a rotational speed (Ul, fRcxr) of the impeller (20).

The valve arrangement (VL; VH) comprises a first adjustable cross sectional area (AVLS ) for controlling the system delivery flow (Y10, Q_OUTS) to the fluid system (52). The valve arrangement (VL; VH) may also comprise a second adjustable cross sectional area (AVLR ) for controlling another flow (QR), such as for example a return flow (QR); said another flow (QR) being diverted from flowing to the fluid system (52).

The at least one set point parameter (UI SP, U2SP) comprises a first valve set point value U2YIOSP for controlling said first adjustable cross sectional area AVLS and/or a second valve set point value U2QRSP for controlling said second adjustable cross sectional area AVLR

According to an example, when said temporal relation value (XI, X 1 (r), FI, FI(r)) indicates a current operating point (205) with a lower pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y IOREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said rotation speed set point value (UISP, f_ROTSP) so as to increase said impeller rotational speed (Ul, fRor), e.g. until said temporal relation value (XI, XI (r), FI, FI(r)) indicates a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP); and said control module (150B, 755) is configured to adjust said first valve set point value U2YIOSP SO as to decrease said first adjustable cross sectional area (AVLS ), and/or to adjust said a second valve set point value U2QRSP SO as to increase said second adjustable cross sectional area (AVLR )•

In this manner, i.e. by decreasing said first adjustable cross sectional area AVLS and/or by increasing said second adjustable cross sectional area AVLR the desired system delivery flow YI OREF, Q_OUTSREF may be obtained while also enabling the pump 10 to run at, or substantially at, Best Efficiency Point of flow Y2BEP, Q_OUTBEP.

In this manner, for example, an oversized pump that was running at a speed of revolution below BEP flow is operated to increase pump outlet fluid flow (Y2, QOUT), thereby advantageously allowing the pump to run at a more energy efficient point of operation 205 at or near BEP flow, and a surplus flow, i.e. a difference between pump outlet fluid flow at BEP (Y2BEP, Q_OUTBEP) and the system delivery flow (Y10, Q_OUTS), may be directed as a return flow.

Figure 43 is an illustration of an example of another pump 10, 4110. The pump 10, 4110 comprises a casing 62 in which a rotatable impeller 20 is disposed so that it can rotate around an axis of rotation 60. The casing 62 defines a pump inlet 64 for fluid material 30, and an outlet 66 for the fluid material 30.

The pump 10, 4110 depicted in figure 43 is a liquid ring pump (LRP) having a number L of vanes (or blades). The number of vanes in figure 34 is twelve (L = 12). A reference signal is typically generated at least once every full revolution of the impeller 20. A vibration sensor (not shown) is applied on the casing 62 or on an outlet tube of the pump and generates a vibration signal. A peak value of the vibration signal is detected a number of times, equal to L, for every full revolution. A phase angle Fl, also referred to as a temporal relation value XI, is generated. The phase angle Fl will change during operation of the pump, such as at different rpm (revolutions per minute) values. As an example, the phase angle Fl constitutes a parameter indicative of an internal state of the pump.

Referring to figure 43, according to an example, there is disclosed a method for monitoring and/or operating a pump 10; 10A; 10B; 10C; 10D having a casing in which a rotatable part 20, 2000 is disposed for urging a fluid material 30 from an inlet to an outlet, the method comprising: receiving a measuring signal indicative of a vibration in the casing and/or a fluid pressure pulsation PFP in the fluid material 30; receiving a reference signal indicative of a rotational reference position of said rotating part 20, 2000; generating data indicative of an internal state of the pump, said data including a phase value FI, FI(r), Xl(r) and/or a temporal relation value FI, FI(r), Xl(r) based on said measuring signal and said reference signal.

The data indicative of an internal state of the pump may be generated as discussed, indicated or expressed in relation to any of the figures 1 A to 40 in this disclosure. Referring to figure 43, according to an example, said casing 62 forms a chamber 68 in which said rotatable part 2000 is disposed for rotating around an axis 60; said axis 60 being offset in relation to a centre of said chamber 68.

Referring to figure 43, according to an example, said fluid material 30 is in a gaseous phase, said rotatable part 2000 is an impeller 20; and said casing forms a chamber 68 in which said rotatable impeller 20, 2000 disposed for rotating around an axis 60; said axis 60 being offset in relation to a centre of said chamber 68; and wherein, in operation, said chamber 68 is partly filled with a liquid; and wherein, when said impeller 20 rotates at a speed fROT exceeding a certain limit speed value, said liquid forms a ring so that the pump operates as a liquid ring pump; said liquid ring pump having an inlet for the gaseous material 30 and an outlet for the gaseous material 30.

Figure 44 A-C shows a basic operation of a liquid ring pump. Referring to figure 43 and figure 44 A-C, according to an example, said impeller 20 has a first number L of vanes or blades that co-operate with said liquid ring (water ring) to form compartments Cl, C3; and wherein the compartments Cl, during operation of the pump, expand when communicating with said inlet so as to cause liquid or gaseous material 30 to enter the pump chamber, and wherein the compartments C3, during operation of the pump, contract when communicating with said outlet so as to cause liquid or gaseous material 30 to exit the pump chamber.

Further, there is typically a compartment C2 that, during operation of the pump, contracts when it does not communicate with said inlet or said outlet. This may be an essential feature of a claim or example herein.

Referring to figure 43, according to an example, the method may further comprise the steps: generate, with a sensor, a measurement signal SEA dependent on mechanical movement caused by operation of the pump; generate, with a position sensor, a position signal indicative of a rotational position of said rotating part; record, with a signal recorder,

- a time sequence of measurement sample values Se(i), S(j) of said digital measurement signal SEA, SMD, and

- a time sequence of said position signal values P(i), and

- time information i, dt; j such that an individual measurement sample value S(j) is associated with data indicative of time of occurrence of the individual measurement data value S(j), and such that an individual position signal value P(i) is associated with data indicative of time of occurrence of the individual position signal value P(i); detect, with a processor, the occurrence of an event, such as e.g. an amplitude peak value, in said recorded time sequence of measurement sample values Se(i), S(j); generate, with a processor, data indicative of an internal state of the pump, said data including a phase value FI, FI(r), Xl(r) and/or a temporal relation value FI, FI(r), Xl(r) based on said measuring signal and said reference signal; and/or generate, with a processor, data indicative of said first temporal relation XI; FI(r), <D(r) based on said detected event occurrence and said time sequence of measurement sample values (Se(i), S(j)).

Figures 44 A, 44 B, 44 C are illustrations of the functions of the different compartments Cl and C3 during rotation of the impeller 20 and the liquid ring of the pump of figure 43. Compartment Cl is expanding when impeller 20 rotates clockwise resulting in a lower pressure in compartment Cl . The lower pressure sucks in gaseous material 30 from the inlet 64. Compartment C3 is contracting when impeller 20 rotates clockwise resulting in a higher pressure in compartment C3. The higher-pressure pushes gaseous material 30 into the outlet 66.

Figure 45 is a diagram illustrating velocity vibrations obtained by measurements on a specific pump similar in its design to the pump 10, 41 10 of figures 43 and 44 and having corresponding parts. The specific pump was operated to create vacuum (or underpressure). The diagram is a “circular plot” of velocity vibrations (variations) of the pump, which has sixteen (L = 16) impeller vanes (or blades).

A sensor for sensing the velocity vibrations was located in or on the outlet 66 or downstream of the outlet 66. The location of the sensor can for example be stated as close enough to the outlet for the sensor to distinguish the velocity vibrations arising through the operation of the pump, such as in a given operating environment. The sensor location may preferably be incorporated in the casing of the pump.

The circular plot shows generally a sixteen-armed star-shape with rather soft points and somewhat uneven edges constituting an actual measurement result and it represents several superimposed full revolutions 0 - 360 degrees of the impeller around the central axis. A clear variation in the amplitude indicates that there is a velocity vibration pulse frequency (per a full revolution of the impeller) equal to the number of impeller vanes (in this case 16 pulses per revolution).

Figure 46 is another diagram in the form of a polar plot based on actual measurements on the same pump as that of figure 45. It shows a stretched out but rather concentrated cluster of dots corresponding to amplitudes (distance from centre) and phases (angle taken from the horizontal line) at different operational states, such as at different rpm of the impeller. To achieve this polar plot, a reference is reset for every passage of an impeller vane, that is, sixteen time for every full revolution for this specific pump.

Based on the plots of figures 45 and 46, a general conclusion may seem plausible: A liquid ring pump tends to produce velocity vibrations at its output with a frequency (per revolution) equal to the number of its impeller blades. Further, the amplitude and phase of the velocity vibrations will vary depending on rotational speed of the impeller and other quantities. The measurement results of figures 45 and 46 seem to indicate that the design of the liquid ring pump causes velocity vibrations having amplitudes X2 and phases XI (here for L = 16) according to a similar pattern as in a centrifugal pump. There also appears to exist some kind of Best Efficiency Point, BEP, for liquid ring pumps. Such a BEP may be identified as corresponding to dots or a dot cluster located closest to the centre (the 0,0 point) of the diagram. Figure 47 is another diagram in the form of a polar plot based on actual measurements on LRP different to that of figure 45. In this polar plot, it is more pronounced that there is a certain portion of the dot cluster that is particularly close to the centre of the diagram, thus indicating an amplitude minimum in the velocity vibrations, see the dotted line in the plot. It is believed that this amplitude minimum corresponds to a best efficiency point, BEP, for the specific pump of figure 47.

Various examples are disclosed below:

An example 1 relates to a system for monitoring an internal state of a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a volute (75), and a shaped portion (63) separating a first part (77) of the volute (75) from a second part (78) of the volute so as to form a pump outlet (66) for delivering a fluid material (30) from the volute, the impeller (20) defining a number (L) of impeller passages for urging the fluid material (30) into the volute (75) by centrifugal force when the impeller (20) rotates thereby causing a fluid pressure pulsation (PFP ) or vibration (VFP) having a repetition frequency (fp) dependent on an impeller speed of rotation (f_ROT).

2. The system according to any preceding example, further comprising: a monitoring unit (150B) for receiving a first measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) including a time sequence of signal sample values (Se(i), S(j), S(q)) indicative of vibration (VFPI) exhibited by a first casing part defining said first volute part (77); and a second measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) including a time sequence of signal sample values (Se(i), S(j), S(q)) indicative of vibration (VFP2) exhibited by a second casing part (XI 02) defining said second volute part (78); said monitoring unit including a status parameter extractor (450) configured to detect, in said first measuring signal, an occurrence of a first pressure pulsation event signature (Sp(r); Sp); said status parameter extractor (450) being configured to detect, in said second measuring signal, an occurrence of a second a pressure pulsation event signature (Sp(r); Sp). 3. The system according to any preceding example, wherein: said status parameter extractor (450) is configured to generate data indicative of a temporal relation between said first pressure pulsation event signature and said second pressure pulsation event signature; and an analyser for detecting said internal state of said centrifugal pump ( 10) based on said temporal relation.

4. The system according to any preceding example, wherein: said status parameter extractor (450) is configured to generate data indicative of a mutual order of occurrence between said first pressure pulsation event signature and said second pressure pulsation event signature; and, an analyser (X451) for evaluating or detecting an internal state of said centrifugal pump (10) based on said mutual order of occurrence.

An example 5 relates to a system for monitoring an internal state of a centrifugal pump (10) having a rotatable impeller (20) having a number (L) of vanes (310) for engaging a fluid material (30) when the impeller (20) rotates thereby causing a fluid pressure pulsation (PFP ) or vibration (VFP) having a repetition frequency (fx) dependent on a speed of rotation (fRo r) of said impeller (20).

6. The system according to any preceding example, comprising: a monitoring unit for receiving a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20), and a signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP ) or vibration (VFP), said monitoring unit being configured to extract, from said measuring signal and said position signal, a first status value (Rr(r); TD; FI(r)) indicative of an operating point of said centrifugal pump (10).

7. The system according to any preceding example, comprising: a status parameter extractor (450) configured to detect a first occurrence of a first reference position signal value (1; 1C, 0%) in a time sequence of position signal sample values

(P(i), PG), P(q)); said status parameter extractor (450) being configured to detect a second occurrence of a second reference position signal value (1; 1C; 100%) in said time sequence of position signal sample values (P(i), PG), P(q)); said status parameter extractor (450) being configured to detect a third occurrence of an event signature (Sp(r); Sp) in a time sequence of signal sample values (Se(i), S ), S(q)); said status parameter extractor (450) being configured to generate data indicative of a first duration between said first occurrence and said second occurrence; and said status parameter extractor (450) being configured to generate data indicative of a second duration between said third occurrence and at least one of said first occurrence and/or said second occurrence; said status parameter extractor (450) being configured to generate data indicative of a first temporal relation (Rr(r); TD; FI(r)) between said second duration, and said first duration; and an analyser (X451) for evaluating an internal state of said centrifugal pump (10) based on an operating point reference value (FIREFO-) ), said first temporal relation (Rr(r); TD; FI(r)), and an operating point error value (FlERR(r) ), wherein said operating point error value (FlERR(r) ) depends on said operating point reference value (FIREFW ), and said first temporal relation (Rq-(r); TD; FI(r)).

An example 8 relates to a system for monitoring an internal state of a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a volute (75) and a shaped portion (63) forming a pump outlet (66) thereby separating a first part (77) of the volute (75) from a second part of the volute, the impeller (20) defining a number (L) of impeller passages for urging a fluid material (30) into the volute (75) by centrifugal force when the impeller (20) rotates causing a casing vibration (VFP) having a repetition frequency (fa) dependent on a speed of rotation (fRor) of the impeller (20).

9. The system according to any preceding example, comprising: a monitoring unit for receiving a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing, and a signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP ) or vibration (VFP), said monitoring unit comprising a status parameter extractor (450) configured to extract, from said measuring signal and said position signal, a first status value (R?(r); TD; FI(r); XI) indicative of said internal state, such as an operating point, during operation of said centrifugal pump (10).

10. The system according to any preceding example, wherein the shaped portion includes a volute tongue separating a first part (77) of the volute (75) from a second part of the volute.

11. The system according to any preceding example, wherein said first volute part (77) having a first cross sectional area, and said second volute part having a second cross sectional area, said first cross sectional area being smaller than said second cross sectional area.

12. The system according to any preceding example, wherein a vibration sensor is attachable to said casing for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)); said vibration sensor being configured to generate said measuring signal based on vibration (VFPI) exhibited by said casing; and/or a strain gauge is attachable to said casing for generating a measuring signal (SFP; SEA, S D, Se(i), S(j), S(q)); said strain gauge being configured to generate said measuring signal based on deformation (VFPI) of said casing caused by fluid pressure pulsation (PFP ); and/or a pressure sensor for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) is mountable so as to detect a fluid pressure pulsation (PFP ) in said fluid material (30).

1 . The system according to any preceding example, wherein a position marker (180) is provided on a rotatable part configured to rotate when the rotatable impeller (20) rotates, and a position sensor is configured to generate a position signal indicative of a predetermined rotational position of said rotatable impeller (20), said position signal including a time sequence of position signal values (P(i), P(j), P(q)).

14. The system according to any preceding example, comprising a first sensor for generating a first measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)); said first sensor being configured to generate said first measuring signal based on vibration (VFPI) exhibited by a first casing part (XI 01) defining said first volute part (77); and a second sensor for generating a second measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)); said second sensor being configured to generate said second measuring signal based on vibration (VFP2) exhibited by a second casing part (XI 02) defining said second volute part (78).

An example 15 relates to a system for monitoring an internal state of a centrifugal pump (10) having a rotatable impeller (20) having a number (L) of vanes (310) for engaging a fluid material (30) when the impeller (20) rotates, thereby causing a fluid pressure pulsation (PFP ) or vibration (VFP) having a repetition frequency (fR) dependent on a speed of rotation (fROT) of the impeller (20).

An example 16 relates to a system for monitoring an internal operating state of a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a volute (75) and a shaped portion (63) forming a pump outlet (66) thereby separating a first part (77) of the volute (75) from a second part of the volute, the impeller (20) defining a number (L) of impeller passages for urging a fluid material (30) into the volute (75) by centrifugal force when the impeller (20) rotates causing a casing vibration (VFP) having a repetition frequency (fa) dependent on a speed of rotation (FROT) of the impeller (20).

An example 17 relates to a system for monitoring an internal operating state of a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a volute (75) and a shaped portion (63) forming a pump outlet (66) thereby separating a first part (77) of the volute (75) from a second part of the volute, the impeller (20) defining a number (L) of impeller passages for urging a fluid material (30) into the volute (75) by centrifugal force when the impeller (20) rotates causing a pulsation (Vp), in said fluid material (30), the pulsation (Vp) having a repetition frequency (FR) dependent on a speed of rotation (FROT) of the impeller (20).

18. The system according to any preceding example, wherein said fluid material pulsation causes a vibration (VFP) of the casing (62).

19. The system according to any preceding example, comprising a monitoring unit for receiving a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of the rotatable impeller (20) during operation of the centrifugal pump (10), and a signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP ) or vibration (VFP).

20. The system according to any preceding example, comprising a status parameter extractor (450) configured to extract, from said measuring signal and said position signal, data indicative of a first status value (R?(r); TD; FI(r); XI) indicative of said internal state of said centrifugal pump (10).

21 . The system according to any preceding example, comprising

- a monitoring unit for receiving a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20), and a signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP ) or vibration (VFP), said a monitoring unit including

- a status parameter extractor (450) configured to detect a first occurrence of a first reference position signal value (1 ; 1C, 0%) in a time sequence of position signal sample values (P(i), PG), P(q)); said status parameter extractor (450) being configured to detect a second occurrence of a second reference position signal value (1 ; 1C; 100%) in said time sequence of position signal sample values (P(i), P ), P(q)); said status parameter extractor (450) being configured to detect a third occurrence of an event signature (Sp(r); Sp) in a time sequence of signal sample values (Se(i), SQ), S(q)); said status parameter extractor (450) being configured to generate data indicative of a first duration between said first occurrence and said second occurrence; and said status parameter extractor (450) being configured to generate data indicative of a second duration between said third occurrence and at least one of said first occurrence and/or said second occurrence; said status parameter extractor (450) being configured to generate data indicative of a first relation (Rr(r); TD; FI(r); XI) between said second duration, and said first duration; and

- an analyser (X451) for detecting said internal state of said centrifugal pump (10) based on said first relation (R_T(r); TD; FI(r)).

22. The system according to example 21, wherein said first relation (Rr(r); TD; FI(r)) constitutes a first status value (Rr(r); TD; FI(r); XI).

23. The system according to any preceding example, wherein said analyser is configured to detect said internal state based on an operating point reference value (FlREp(r) ), said first relation (R-r(r); TD; FI(r)), and an operating point error value (FlERR(r) ), wherein said operating point error value (FlERR(r) ) depends on said operating point reference value (FIREFG) ), and said first temporal relation (R-r(r); TD; FI(r)).

24. The system according to any preceding example, comprising: a status parameter extractor (450) configured to detect a first occurrence of a first reference position signal value (1 ; 1C, 0%) in a time sequence of position signal sample values (P(i), P(j), P(q)); said status parameter extractor (450) being configured to detect a second occurrence of a second reference position signal value (1 ; 1C; 100%) in said time sequence of position signal sample values (P(i), P(j), P(q)); said status parameter extractor (450) being configured to detect a third occurrence of an event signature (Sp(r); Sp) in a time sequence of signal sample values (Se(i), S(j), S(q)); said status parameter extractor (450) being configured to generate data indicative of a first duration between said first occurrence and said second occurrence; and said status parameter extractor (450) being configured to generate data indicative of a second duration between said third occurrence and at least one of said first occurrence and/or said second occurrence; said status parameter extractor (450) being configured to generate data indicative of a first relation (R (r); TD; FI(r)) between said second duration, and said first duration; and an analyser (X451) for evaluating an internal state of said centrifugal pump (10) based on an operating point reference value (FIREFW L said first relation (R (r); TD; FI(r)), and an operating point error value (FIERRO-) ), wherein said operating point error value (FIERRO-) ) depends on said operating point reference value (FIREFW )> and said first relation (R (r); TD; FI(r)).

25. The system according to any preceding example, wherein: said analyser (X451) generates said first status value (Rr(r); TD; FI(r)) indicative of an operating point of said centrifugal pump (10) based on said first relation (R-r(r); TD; FI(r)).

26. The system according to any preceding example, wherein: said operating point reference value (FlREF(r) ) is a predetermined relation value indicative of a Best Efficiency Point of operation of said centrifugal pump (10); and said analyser (X451) generates said first status value (R (r); TD; FI(r)) indicative of an operating point of said centrifugal pump (10) based on said operating point error value (FI_ERR(r) ).

27. The system according to any preceding example, further comprising a sensor for generating said measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) when said centrifugal pump (10) exhibits said fluid pressure pulsation (PFP ) or vibration (VFP).

28. The system according to any preceding example, wherein: said centrifugal pump ( 10) includes said rotatable impeller (20); and a casing (62) in which the impeller (20) is disposed, the casing (62) having an inlet (64) for receiving said fluid material (30), and an outlet (66) for delivering said fluid material (30) impelled by said impeller

(20) when said impeller (20) rotates; and wherein said sensor is configured to generate said measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) when said casing exhibits said vibration (VFP).

29. The system according to any preceding example, wherein: said casing (62) defines a volute (75) configured as a curved funnel that increases in cross sectional area as it approaches said outlet (66).

30. The system according to any preceding example, wherein: said impeller (20) vanes (310) define a number (L) of impeller passages for urging said fluid material (30) into said volute (75) by centrifugal force when said impeller (20) rotates.

31. The system according to any preceding example, wherein: said centrifugal pump (10) includes said rotatable impeller (20); and a casing (62) in which the impeller (20) is disposed, said casing (62) defining a volute (75) configured as a curved funnel having a cross sectional area; said casing (62) having a shaped portion (63) for separating a first part (77) of said volute (75) from a second part (78) of said volute; said first volute part (77) having a first cross sectional area, and said second volute part (78) having a second cross sectional area, said first cross sectional area being smaller than said second cross sectional area.

32. The system according to any preceding example, further comprising: a first sensor for generating a first measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)); said first sensor being configured to generate said first measuring signal based on vibration (VFPI) exhibited by a first casing part (X101) defining said first volute part (77); and a second sensor for generating a second measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)); said second sensor being configured to generate said second measuring signal based on vibration (VFPZ) exhibited by a second casing part (XI 02) defining said second volute part (78); a status parameter extractor (450) configured to detect a fourth occurrence of an event signature (Sp(r); Sp) in a time sequence of first measuring signal sample values (Se(i), S(j), S(q)); said status parameter extractor (450) being configured to detect a fifth occurrence of said event signature (Sp(r); Sp) in a time sequence of second measuring signal sample values (Se(i), S(j), S(q)); said status parameter extractor (450) being configured to generate data indicative of a mutual order of occurrence between said fourth occurrence and said fifth occurrence; and, an analyser (X451) for evaluating an internal state of said centrifugal pump (10) based on said mutual order of occurrence.

An example 33 relates to a system comprising

- a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a central pump inlet (64) for a fluid material (30), an outlet (66), and a volute (75), the rotatable impeller (20) having a number (L) of vanes for urging, when the rotatable impeller (20) rotates, the fluid material (30) from the central pump inlet (64) into the volute (75), thereby causing a fluid material pulsation (Vp) having a repetition frequency (fp) dependent on a speed of rotation (IROT) of the rotatable impeller (20); the system further comprising

- a sensor for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation (Vp);

- a position sensor for generating a signal (EP, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing, and

- a status parameter extractor (450) configured to extract, from said measuring signal and said position signal, a first status value (Rr(r); TD; FI(r); XI) indicative of an internal state of said centrifugal pump (10) during operation.

34. The system according to any preceding example, wherein: the rotatable impeller (20) has a number (L) of vanes for urging, when the rotatable impeller (20) rotates, the fluid material (30) from the central pump inlet (64) into the volute (75), thereby causing a fluid material flow with a pulsation (Vp) having a repetition frequency (fp) dependent on a speed of rotation (IROT) of the rotatable impeller (20).

An example 35 relates to a system for monitoring an internal state of a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a volute (75) and a shaped portion (63) forming an outlet (66), the rotatable impeller (20) defining a number (L) of impeller passages for urging, when the impeller (20) rotates, a fluid material (30) into the volute (75), thereby causing a fluid material pulsation (Vp) having a repetition frequency (fp) dependent on a speed of rotation (fpcrr) of the impeller (20); the system comprising a sensor for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation (Vp); a position sensor for generating a signal (EP, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing, and a status parameter extractor (450) configured to extract, from said measuring signal and said position signal, a first status value (R_T(r); TD; FI(r); XI) indicative of said internal state during operation of said centrifugal pump (10).

36. The system according to any preceding example, wherein: said sensor is configured to generate said measuring signal based on vibration (VFPI) exhibited by the casing in response to the fluid material pulsation (Vp).

37. The system according to any preceding example, wherein said sensor is attached to the casing (62).

38. The system according to any preceding example, wherein a position marker (180) is provided on a rotatable part configured to rotate when the rotatable impeller (20) rotates, and said position sensor (170) is configured to generate said position signal (Ep, P(i), P(j), P(q)) dependent on said position marker (180).

39. The system according to any preceding example, wherein: said status parameter extractor (450) is configured to detect a first occurrence of a first reference position signal value (1; 1C, 0%) in a time sequence of position signal sample values (P(i), PG), P(q)); said status parameter extractor (450) being configured to detect a second occurrence of a second reference position signal value (1 ; 1C; 100%) in said time sequence of position signal sample values (P(i), P0), P(q)); said status parameter extractor (450) being configured to detect a third occurrence of an event signature (Sp(r); Sp) in a time sequence of signal sample values (Se(i), SQ), S(q)); said status parameter extractor (450) being configured to generate data indicative of a first duration between said first occurrence and said second occurrence; and said status parameter extractor (450) being configured to generate data indicative of a second duration between said third occurrence and at least one of said first occurrence and/or said second occurrence; said status parameter extractor (450) being configured to generate data indicative of a first relation (R-r(r); TD; FI(r)) between said second duration, and said first duration.

40. The system according to any preceding example, wherein: said data indicative of a first relation(RT(r); TD; FI(r); XI) is said first status value (R_T(r); T_D; FI(r); XI).

41 . The system according to any preceding example, further comprising an analyser (X451) for evaluating the internal state of the centrifugal pump (10) based on an operating point reference value (FIREXO X said first relation (RT(F); TD; FI(r)), and an operating point error value (FlERR(r) ), wherein said operating point error value (FlERR(r) ) depends on said operating point reference value (FlREp(r) ), and said first relation (R?(r); TD; FI(r)).

42. The system according to any preceding example, wherein: when said operating point reference value (FIREXO ) is adjusted to a value indicating a pump best efficiency flow (BEP), then said operating point error value (FlERR(r) ) is indicative of a pump operating point deviating from said pump best efficiency flow (BEP).

43. The system according to any preceding example, wherein: when said operating point reference value (FIREXO ) is adjusted to a value indicating a pump best efficiency flow (BEP), then a deviation of said operating point error value (FlERR(r) ) from a zero value is indicative of a pump operating point deviating from said pump best efficiency flow (BEP). 44. The system according to any preceding example, wherein said measuring signal includes a time sequence of signal sample values (Se(i), S(j), S(q)) indicative of vibration (VFPI) exhibited by the casing; and said position signal includes a time sequence of position signal values (P(i), P(j), P(q)).

45. The system according to any preceding example, further comprising a shaped portion (63) forming said outlet (66).

46. The system according to any preceding example, wherein a shaped portion (63) couples the volute to the outlet (66) of the pump.

47. The system according to any preceding example, wherein the shaped portion (63) includes a volute tongue separating a first part (77) of the volute (75) from a second part of the volute.

48. The system according to any preceding example, wherein the outlet (66) includes a volute tongue separating a first part (77) of the volute (75) from a second part of the volute.

49. The system according to any preceding example, wherein said position marker (180) is positioned on said rotatable part such that said position signal (Ep, P(i), P(j), P(q)) includes a reference position signal value (1; 1C, 0%; 100%) at a predetermined angular position in relation to said volute tongue .

50. The system according to any preceding example, wherein said position marker (180) is positioned on said rotatable part such that said position signal (Ep, P(i), P(j), P(q)) includes a reference position signal value (1 ; 1C, 0%; 100%) indicating at least one predetermined angular position in relation to said outlet (66).

51. The system according to any preceding example, wherein the rotatable impeller (20) includes vanes (310) defining said number (L) of impeller passages.

52. The system according to any preceding example, in particular when dependent on example 49, wherein said status parameter extractor (450) is configured to detect an occurrence of an event signature (Sp(r); Sp) in a time sequence of signal sample values (Se(i), S(j), S(q)).

53. The system according to any preceding example, in particular when dependent on example 49, wherein said status parameter extractor (450) is configured to detect an occurrence of an event signature (Sp(r); Sp) in a time sequence of signal sample values (Se(i), S(j), S(q)); and said status parameter extractor (450) is configured to generate data indicative of an angular position of the rotatable impeller (20) at the occurrence of said event signature (Sp(r); Sp) based on said reference position signal value (1; 1C, 0%; 100%) and said time sequence of signal sample values (Se(i), S(j), S(q)).

An example 54 relates to a system comprising a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a central pump inlet (64) for a fluid material (30), an outlet (66), and a volute (75), the rotatable impeller (20) having a number (L) of vanes for urging, when the rotatable impeller (20) rotates, the fluid material (30) from the central pump inlet (66) into the volute (75), thereby causing a fluid material flow with a pulsation (Vp) having a repetition frequency (fp) dependent on a speed of rotation (fROT) of the rotatable impeller (20); the system further comprising a sensor for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation (Vp); a position sensor for generating a signal (Ep, P(i), P j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing, and a status parameter extractor (450) configured to extract, from said measuring signal and said position signal, a first status value (R_T(r); TD; FI(r); XI) indicative of an internal state of said centrifugal pump (10) during operation.

55. The system according to any preceding example, wherein said measuring signal includes a time sequence of signal sample values (Se(i), S(j), S(q)) indicative of vibration (VFPI ) exhibited by the casing; and said position signal includes a time sequence of position signal values (P(i), P(j), P(q)); said time sequence of position signal values (P(i), P(j), P(q)) including a reference position signal value (1; 1C, 0%; 100%) indicative of a predetermined angular position of the rotatable impeller in relation to said casing.

56. The system according to any preceding example, in particular when dependent on example

55, wherein said status parameter extractor (450) is configured to detect an occurrence of an event signature (Sp(r); Sp) in a time sequence of signal sample values (Se(i), S(j), S(q)); and said status parameter extractor (450) is configured to generate, based on said reference position signal value (1 ; 1C, 0%; 100%) and said time sequence of signal sample values (Se(i), S(j), S(q)), data indicative of an angular position of the rotatable impeller (20) in relation to said casing at the occurrence of said event signature (Sp(r); Sp).

57. The system according to any preceding example, in particular when dependent on example

56, wherein

Said data indicative of an angular position of the rotatable impeller (20) in relation to said casing at the occurrence of said event signature (Sp(r); Sp) is said first status value (R-r(r); T_D; FI(r); XI). 58. The system according to any preceding example, wherein the fluid material pulsation causes a vibration (VFP) of the casing (62).

59. The system according to any preceding example, wherein said operating point error value (FlERR(r) ) depends on a difference between said operating point reference value (FlREF(r) ), and said first relation (Rr(r); TD; FI(r)).

60. The system according to any preceding example, wherein said operating point error value (FlERR(r) ) is indicative of a pump operating point deviating from said operating point reference value (FlREp(r) ).

61. The system according to any preceding example, further comprising a drive motor for causing said speed of rotation (fRor) of the impeller (20) in response to a drive motor speed control signal (Ulsp); wherein said operating point error value (FIERRO-) ) is indicative of a deviation of a drive motor control signal value from a drive motor set point (Ulsp, FROTSP) associated with said operating point reference value (FIREF(F) )•

62. The system according to any preceding example, further comprising a drive motor for causing said speed of rotation (fRor) of the impeller (20) in response to a drive motor speed control signal; wherein said operating point error value (FIERRW ) is indicative of a deviation (FROT ERR( ) of said impeller rotational speed (FROT) from an impeller rotational speed set point (f_ROT SP; U1SP, FROTSP).

63. The system according to any preceding example, further comprising a regulator for controlling said impeller rotational speed (FROT) based on an operating point reFerence value (FIREFO ), said first relation (Rr(r); TD; FI(r)), and an operating point error value (FlERR(r) ), wherein said operating point error value (FlERR(r) ) depends on said operating point reference value (FlREF(r) ), and said first relation (R-r(r); TD; FI(r)).

64. The system according to any preceding example, further comprising a drive motor for causing the impeller (20) to rotate at said speed of rotation (f_ROT) in response to a drive motor speed control signal; wherein said regulator is configured to control an impeller rotational speed set point (f oT Sp; U1SP, FROTSP) in dependence on said operating point reference value (FIREFW ).

65. The system according to any preceding example, wherein

Said event signature (Sp(r); Sp) is a measuring signal amplitude peak value.

66. The system according to any preceding example, wherein a said impeller passage is a passage from a pump inlet (64) to said volute.

67. The system according to any preceding example, wherein a said impeller passage is a rotatable passage having an impeller opening facing said volute such that the impeller opening rotates when the impeller rotates.

68. The system according to any preceding example, further comprising a piping system (52), coupled to said pump outlet (66), for receiving said fluid material (30)

69. The system according to any preceding example, wherein said regulator is configured to control a volute set point value (U2SP) in dependence on said operating point reference value (FlREF(r) ), and wherein said volute is an adaptive volute (75) having an adjustable volume, and wherein said volute set point value (U2SP; VPSP) controls said adjustable volute volume.

70. The system according to according to any preceding example, wherein said event signature is indicative of an fluid pressure (PFL, P54) generated when the rotating the impeller (20) interacts with said fluid material (30). 71. The system according to according to any preceding example, wherein said status parameter extractor (450) is configured to generate said first temporal relation (R (r); TD; FI(r)) as a phase angle (FI(r)).

72. The system according to according to any preceding example, wherein said status parameter extractor (450) is configured to generate said event signature as an amplitude value (Sp(r); Sp; Ct(r); Ci(r)).

73. The system according to according to any preceding example, wherein said status parameter extractor (450) comprises a Fourier Transformer configured to generate said first temporal relation (R (r); TD; FI(r)).

74. The system according to according to any preceding example, wherein said status parameter extractor (450) is configured to count a total number of samples (NB) from the first occurrence to the second occurrence, and said status parameter extractor (450) is configured to count another number of samples (Np) from the first occurrence to the third occurrence, and said status parameter extractor (450) is configured to generate said first temporal relation (Rr(r); TD; FI(r)) based on said another number and said total number; or wherein said status parameter extractor (450) is configured to count a total number of samples (NB) from the first occurrence to the second occurrence, and said status parameter extractor (450) is configured to count another number of samples (Np) from the first occurrence to the third occurrence, and said status parameter extractor (450) is configured to generate said first temporal relation (Ri (r); TD; FI(r)) based on a relation between said another number and said total number, wherein: said relation between said another number and said total number is indicative of internal state of said centrifugal pump (10).

An example 75 relates to a system for monitoring an internal operating state of a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a volute (75) and a shaped portion (63) forming a pump outlet (66) thereby separating a first part (77) of the volute (75) from a second part of the volute, the impeller (20) defining a number (L) of impeller passages for urging a fluid material (30) into the volute (75) by centrifugal force when the impeller (20) rotates causing a pulsation (Vp), in said fluid material (30), the pulsation (Vp) having a repetition frequency (fp) dependent on a speed of rotation (f_ROT) of the impeller (20).

An example 76 relates to a system for monitoring an internal state of a centrifugal pump (10) having a rotatable impeller (20) including vanes (310) defining a number (L) of impeller passages for urging a fluid material (30) into a volute (75) when the impeller (20) rotates thereby causing a fluid material pulsation (VP) having a repetition frequency (fR) dependent on a speed of rotation (fROT) of the impeller (20).

An example 77 relates to a centrifugal pump arrangement (780; 940) comprising a centrifugal pump ( 10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a pump inlet (64) for a fluid material (30), an outlet (66) for the fluid material (30), and a volute (75), the rotatable impeller (20) having a number (L) of vanes for urging, when the rotatable impeller (20) rotates, the fluid material (30) from the pump inlet (64) into the volute (75), thereby causing a fluid material flow with a pulsation (Vp) having a repetition frequency (fp) dependent on a speed of rotation ((ROT) of the rotatable impeller (20); the centrifugal pump arrangement (X310) further comprising a sensor for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation (VP); a position sensor for generating a position signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing, and a pump location data port (820, X211), connectable to a communications network (810), for data exchange with a pump monitoring apparatus (880, 150A) for monitoring of an internal status of said centrifugal pump (10); a pump location communications device (790) being configured to deliver, via said pump location data port (820, X211): data indicative of said measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)), and data indicative of said position signal (Ep, P(i), P(j), P(q)).

An example 78 relates to a pump monitoring apparatus (880, 150A) for cooperation with a centrifugal pump arrangement (780; 940; X310) according to any preceding example, the pump monitoring apparatus (880, 150A;X320) comprising: a monitoring apparatus data port (920, 920A,920B, 720, X221), connectable to a communications network (810), for data exchange with said centrifugal pump arrangement (780; 940; X310); a monitoring apparatus communications device (920, 920A,920B, 720) configured to receive, via said monitoring apparatus data port (920, 920A,920B, 720, X221): data indicative of a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)), and data indicative of a position signal (EP, P(i), P(j), P(q)); the pump monitoring apparatus (880, 150A) further comprising: a status parameter extractor (450) configured to extract, from said measuring signal and said position signal, a first status value (TDI , R-r(r); TD; FI(r); XI) indicative of an internal state of said centrifugal pump (10) during operation.

79. The pump monitoring apparatus according to any preceding example, further comprising: a screen display (210S); and wherein said received measuring signal (SFP; SEA, S D, Se(i), S(j), S(q)) is dependent on fluid material pulsation (Vp); said measuring signal including a time sequence of signal sample values (Se(i), S(j), S(q)); and wherein said status parameter extractor (450) is configured to detect an occurrence of an event signature (Sp(r); Sp) in said time sequence of signal sample values (Se(i), S(j), S(q)); said status parameter extractor (450) is configured to display, on said screen display

(210S), a polar coordinate system, said polar coordinate system having a reference point (O), and a reference direction (0,360); and a first internal status indicator object (Spi, TDI), indicative of said internal state, at a first polar angle (TDI) in relation to said reference direction (0,360), said first polar angle (TDI) being indicative of an angular position of the rotatable impeller (20) in relation to the pump casing at the occurrence of said event signature (Sp(r); Sp).

An example 80 relates to a system comprising a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the casing (62) defining a central pump inlet (64) for a fluid material (30), an outlet (66), and a volute (75), the rotatable impeller (20) having a number (L) of vanes for urging, when the rotatable impeller (20) rotates, the fluid material (30) from the central pump inlet (64) into the volute (75), thereby causing a fluid material pulsation (Vp) having a repetition frequency (fp) dependent on a speed of rotation (fpor) of the rotatable impeller (20).

81. The system according to example 80, further comprising a sensor for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation (Vp); a position sensor for generating a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing, and a status parameter extractor (450) configured to extract, from said measuring signal and said position signal, a first status value (R r(r); TD; FI(r); XI) indicative of an internal state of said centrifugal pump (10) during operation.

82. In a digital monitoring system for generating and displaying information relating to an internal state of a centrifugal pump (10) having a casing defining a volute (75) in which a rotatable impeller (20) is disposed for urging, when the rotatable impeller (20) rotates, a fluid material (30) from a central pump inlet (64) into the volute (75), thereby causing a fluid material flow with a pulsation (Vp) having a repetition frequency (ffr) dependent on a speed of rotation (fRor) of the rotatable impeller (20); a computer implemented method of representing said internal state of said centrifugal pump (10) on a screen display (210S), the method comprising: receiving a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing, said position signal including a time sequence of position signal values (P(i), P(j), P(q)); said time sequence of position signal values (P(i), P(j), P(q)) including a reference position signal value (1; 1C, 0%; 100%) indicative of at least one predetermined angular position of the rotatable impeller in relation to said casing, and receiving a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation (Vp); said measuring signal including a time sequence of signal sample values (Se(i), S(j), S(q)); detecting an occurrence of an event signature (Sp(r); Sp) in said time sequence of signal sample values (Se(i), S(j), S(q)); displaying on said screen display (210S) a polar coordinate system, said polar coordinate system having a reference point (O), and a reference direction (0,360); and a first internal status indicator object (Spi, TDI), indicative of said internal state, at a first polar angle (TDI) in relation to said reference direction (0,360), said first polar angle (TDI) being indicative of an angular position of the rotatable impeller (20) in relation to the pump casing at the occurrence of said event signature (Sp(r); Sp).

83. In a digital monitoring system for generating and displaying information relating to an internal state of a centrifugal pump (10) having a casing defining a volute (75) in which a rotatable impeller (20) is disposed for urging, when the rotatable impeller (20) rotates, a fluid material (30) from a pump inlet (64) into the volute (75), thereby causing a fluid material flow with a pulsation (Vp) having a repetition frequency (fa) dependent on a speed of rotation (fRor) of the rotatable impeller (20); a computer implemented method of representing said internal state of said centrifugal pump (10) on a screen display (210S), the method comprising: receiving a signal (Ep, P(i), P(j), P(q)) including a reference position signal value (1;

1C, 0%; 100%) indicative of at least one predetermined angular position of the rotatable impeller in relation to said casing, and receiving a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation (Vp); said measuring signal including a time sequence of signal sample values (Se(i), S(j), S(q)); detecting an occurrence of an event signature (Sp(r); Sp) in said time sequence of signal sample values (Se(i), S(j), S(q)); displaying on said screen display (210S) a polar coordinate system, said polar coordinate system having a reference point (O), and a reference direction (0,360); and a first internal status indicator object (Spi, TDI), indicative of said internal state, at a first polar angle (TDI) in relation to said reference direction (0,360), said first polar angle (TDI) being indicative of an angular position of the rotatable impeller (20) in relation to the pump casing at the occurrence of said event signature (Sp(r); Sp).

84. In a digital monitoring system for generating and displaying information relating to an internal state of a centrifugal pump (10) having a casing defining a volute (75) in which a rotatable impeller (20) is disposed for urging, when the rotatable impeller (20) rotates, a fluid material (30) from a pump inlet (64) into the volute (75), thereby causing a fluid material flow with a pulsation (Vp) having a repetition frequency (fp) dependent on a speed of rotation (fRor) of the rotatable impeller (20); a computer implemented method of representing said internal state of said centrifugal pump (10) on a screen display (210S), the method comprising: receiving a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing, generate a position reference value (1; 1C, 0%; 100%) based on said position signal (Ep, P(i), P(j), P(q)) such that said position reference value is provided a first number of times per revolution of said rotatable impeller (20), said first number of position reference values being indicative of a first number of predetermined rotational positions of said rotatable impeller (20), and receiving a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation (Vp); said measuring signal including a time sequence of signal sample values (Se(i), S(j), S(q)); detecting an occurrence of an event signature (Sp(r); Sp) in said time sequence of signal sample values (Se(i), S(j), S(q)); displaying on said screen display (210S) a polar coordinate system, said polar coordinate system having a reference point (O), and a reference direction (0,360); and a first internal status indicator object (Spi, TDI), indicative of said internal state, at a first polar angle (TDI , Rr(r); TD; FI(r); XI) in relation to said reference direction (0,360), said first polar angle (TDI) being indicative of an angular position of the rotatable impeller (20) in relation to the pump casing at the occurrence of said event signature (Sp(r); Sp).

85. A computer implemented method for generating and displaying information relating to an internal state of a centrifugal pump (10) having a casing defining a volute (75) in which a rotatable impeller (20) is disposed for urging, when the rotatable impeller (20) rotates, a fluid material (30) from a pump inlet (64) into the volute (75), thereby causing a fluid material flow with a pulsation (Vp) having a repetition frequency (fp) dependent on a speed of rotation (fRor) of the rotatable impeller (20); the method comprising: receiving a signal (Ep, P(i), P(j), P(q)) including a reference position signal value (1;

1C, 0%; 100%) indicative of at least one predetermined angular position of the rotatable impeller in relation to said casing, receiving a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation (Vp); said measuring signal including a time sequence of signal sample values (Se(i), S(j), S(q)); detecting an occurrence of an event signature (Sp(r); Sp, 205) in said time sequence of signal sample values (Se(i), S(j), S(q)); and representing said internal state of said centrifugal pump (10) on a screen display (210S), by displaying on said screen display (210S): a polar coordinate system, said polar coordinate system having a reference point (O), and a reference direction (0,360); and a first internal status indicator object (550; Spi, TDI), indicative of said internal state, at a first polar angle (TDI, Rr(r); TD; FI(r); XI) in relation to said reference direction (0,360), said first polar angle (TDI) being indicative of an angular position of the rotatable impeller (20) in relation to the pump casing at the occurrence of said event signature (Sp(r); Sp, 205).

86. The method according to any preceding example, further comprising: displaying on said screen display (210S) said first internal status indicator object (Spi, TDI) at a first radius (Spi) from said reference point (O), said first radius (Spi) being indicative of an amplitude of said pulsation.

87. The method according to any preceding example, wherein the impeller has said first number of vanes.

88. The method according to any preceding example, wherein wherein a said predetermined rotational position is a position of an impeller vane in relation to a pump outlet.

89. The method according to any preceding example, wherein wherein a said predetermined rotational position is a certain angular position of an impeller vane tip in relation to a pump outlet.

90. The method according to any preceding example, wherein wherein a said predetermined rotational position is a certain angular position of an impeller vane tip in relation to a volute tongue.

91. The method according to any preceding example, wherein said reference direction (0,360) is indicative of a certain angular position of the rotatable impeller in relation to said casing.

92. The method according to any preceding example, wherein said casing includes a volute tongue, and said reference direction (0,360) corresponds to a rotational position where an impeller vane tip is at its closest position in relation to said volute tongue.

93. The method according to any preceding example, wherein said first polar angle (TDI) is indicative of a momentary angular position of the rotatable impeller (20) in relation to the pump casing at the occurrence of said event signature (Sp(r); Sp) during operation of said centrifugal pump.

94. The method according to any preceding example, wherein

Said certain angular position is said predetermined angular position so that said reference position signal value (1; 1C, 0%; 100%) is indicative of said reference direction (0,360).

An example 95 relates to a computer program for performing the method according to any preceding example, the computer program comprising computer program code means adapted to perform the steps of the method according to any preceding example when said computer program is run on a computer. 96. The computer program according to any preceding example, the computer program being embodied on a computer readable medium.

97. The system according to any preceding example, wherein the casing comprises at least two fixed vanes which are positioned between said volute and said impeller.

98. The system according to any preceding example, wherein the casing comprises at least one fixed vane which is positioned at a radial distance from an axis of rotation (60) of said impeller, said radial distance being larger than a radius of said impeller.

99. In a digital monitoring system for generating and displaying information relating to an internal state of a centrifugal pump (10) having a casing defining a volute (75) in which a rotatable impeller (20) is disposed for urging, when the rotatable impeller (20) rotates, a fluid material (30) from a pump inlet (64) towards an outlet (66) via the volute (75); a computer implemented method of representing said internal state of said centrifugal pump (10) on a screen display (210S), the method comprising: receiving a signal (Ep, P(i), P(j), P(q)) including a reference position signal value (1;

1C, 0°,360°) indicative of at least one predetermined angular position of the rotatable impeller in relation to said casing, and receiving a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on a fluid material pulsation (PFP); said measuring signal including a time sequence of signal sample values (S(q)), wherein a sample value (Se(i), S(j), S(q)) has an amplitude value; displaying on said screen display (210S) a polar coordinate system, said polar coordinate system having a reference point (O), and a reference direction (0,360); and an amplitude time plot (570, 570A) including at least one signal sample value (S(q)) plotted at a signal sample polar angle (FI(q) ) in relation to said reference direction (0°,360°) and at a signal sample radius (S(q)) from said reference point (O); said signal sample radius (S(q)) being indicative of an amplitude of said signal sample value (S(q)).

100. The method according to example 99, wherein said amplitude time plot (570, 570A) includes at least a part of said time sequence of signal sample values (S(q)), wherein an individual signal sample value (S(q)) is plotted at an individual signal sample polar angle (FI(q) ) in relation to said reference direction (0°,360°) and at an individual signal sample radius (S(q)) from said reference point (O); and wherein said signal sample polar angle (FI(q) ) corresponds to an angular position of said impeller (20) at a time of detection of said signal sample value (S(q)) during operation of the pump; and said amplitude time plot (570, 570B) has a shape that is indicative of said internal state of the pump (10).

101. A method of operating a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the rotatable impeller (20) having a number (L) of vanes for urging, when the rotatable impeller (20) rotates, the fluid material (30) from a pump inlet (66) into the volute (75), the method comprising receiving a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on a fluid material pulsation (Vp); receiving a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing; generating, based on said measuring signal and said position signal, information indicative of an internal state of the centrifugal pump (10). 102. The method according to example 101 or any preceding example, wherein said generating, includes extraction of a first status value (FI, XI; FI(r); Xl(r)) indicative of an internal state of said centrifugal pump (10) during operation.

103. The method according to according to example 102 or any preceding example, wherein said generating, includes generating an amplitude time plot (570, 570A), wherein said amplitude time plot (570) has a shape that is indicative of an internal state of the pump (10).

104. The method according to example 103 or any preceding example, wherein the amplitude time plot (570) exhibits a predetermined number (L) of signal signatures.

105. The method according to any preceding example, wherein a signal signature exhibits at least one highest amplitude peak, and at least one lowest amplitude peak.

106. The method according to any preceding example, wherein said predetermined number (L) of signal signatures exhibit a uniform shape, or a substantially uniform shape, during normal operation of the pump.

107. The method according to any preceding example, wherein when an individual signal signature exhibits a shape that deviates from the shape of other signal signatures that deviation indicates a malfunction.

108. The method according to any preceding example, wherein when an individual signal signature exhibits a shape that deviates from the shape of the other signal signatures that deviation indicates that a physical feature associated with a vane (310), or a physical feature associated with an impeller passage (320), deviates from normal .

109. The method according to any preceding example, further comprising: detecting an occurrence of an event signature (Sp(r); Sp) in a time sequence of signal sample values (Se(i), S(j), S(q)); and generating, based on said reference position signal value (1; 1C, 0%; 100%) and said time sequence of signal sample values (Se(i), S(j), S(q)), data indicative of an angular position (FI(r); Xl)of the impeller (20) in relation to said casing at the occurrence of said event signature (Sp(r); Sp).

110. The method according to any preceding example, wherein said data indicative of an angular position is said first status value (FI(r); XI).

111. The method according to any preceding example, wherein detecting a first occurrence of a first reference position signal value (1; 1C, 0%) in a time sequence of position signal sample values (P(i), P(j), P(q)); detecting a second occurrence of a second reference position signal value (1 ; 1C;

100%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting a third occurrence of an event signature (Sp(r); Sp) in a time sequence of signal sample values (Se(i), S(j), S(q)); generating data indicative of a first duration between said first occurrence and said second occurrence; and generating data indicative of a second duration between said third occurrence and at least one of said first occurrence and/or said second occurrence; generating data indicative of a first relation (FI, FI(r)) between said second duration, and said first duration.

112. The method according to any preceding example, wherein said data indicative of a first relation(RT(r); TD; FI(r); XI) is said first status value (R_T(r); T_D; FI(r); XI).

113. The method according to any preceding example, further comprising: determining an internal state of the centrifugal pump (10) based on an operating point reference value (FIREFW ), said first relation (Rr(r); TD; FI(r)), and an operating point error value (FIERR -) ), wherein said operating point error value (FlERR(r) ) depends on said operating point reference value (FIREF(F) ), and said first relation (R?(r); TD; FI(r)). 1 14. The method according to any preceding example, further comprising: conveying, to a user interface (210, 210S) information indicative of an internal state (X) of the centrifugal pump (10).

115. The method according to any preceding example, wherein said first status value (FI, XI; FI(r); Xl(r)) is based on a time of occurrence of a fluid pressure pulsation event (Sp(r)) and a time of occurrence of a rotational reference position.

116. The method according to any preceding example, wherein said first status value (XI; Xl(r)) is a temporal relation value (FI, FI(r)) based on a time of occurrence of a fluid pressure pulsation event (Sp(r)) and at least two times of occurrence of a rotational reference position.

117. A computer program comprising program instructions, the computer program being loadable into one or more processors and configured to cause one or more hardware processors to perform the method according to any one of the preceding examples.

118. A computer program product comprising a non-transitory computer-readable storage medium having thereon the computer program according to example 117.

119. A system for monitoring an internal state of a centrifugal pump (10), the system being configured to perform the method according to any preceding example.

120. The system according to example 119, further comprising one or more hardware processors configured to perform the method according to any preceding example.

121. A method of operating a centrifugal pump (10) having a casing forming a volute (75) in which a rotatable impeller (20) is disposed for urging a fluid material (30) into the volute, the method comprising: monitoring a fluid pressure pulsation event inside the pump casing; generating, based on said monitoring, a measuring signal indicative of occurrence of said first fluid pressure pulsation event; generating a reference signal indicative of a rotational reference position of said rotating impeller; determining a temporal relation value (FI, FI(r)) based on time of occurrence of said fluid pressure pulsation event (Sp(r)) and said reference signal.

122. The method of example 121, further comprising determining an operation parameter of the pump based on the determined temporal relation value (FI, FI(r)).

123. The method of example 122, wherein the operation parameter comprises a rotation speed set point value (U 1 SP, f_ROTSP) for controlling a rotational speed (Ul, fRor) of the impeller (20).

124. The method according to any preceding example, wherein said volute is an adaptive volute (75) having an adjustable cross sectional area.

125. The method according to example 124, wherein the operation parameter comprises a volute set point value (U2SP; VPSP) for controlling said adjustable cross sectional area.

126. The method according to any preceding example, wherein said volute is an adaptive volute (75) having a first adjustable cross sectional area (A77) , and a second adjustable cross sectional area (A78) wherein the operation parameter comprises a volute set point value (U2SP; Vpsp) for simultaneously controlling said first and second adjustable cross sectional areas.

127. The method according to any preceding example, wherein said volute is an adaptive volute (75) having an adjustable volume, and wherein the operation parameter comprises a volute set point value (U2SP; VPSP) for controlling said adjustable volute volume. 128. The method according to any preceding example, wherein said volute set point value (U2SP; VPSP) controls a pump outlet fluid volume per impeller revolution.

129. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is indicative of an internal state (205, 550, X)) of said centrifugal pump (10).

130. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point (205, 550; X) of the centrifugal pump (10).

131. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point deviation (FIDEV; FIDEV(P+1); 550(p+ 1 )) from a Best Efficiency Point of operation of the centrifugal pump (10).

132. The method according to any preceding example, further comprising displaying, on a user interface, the determined operation parameter (Ul, f_ROT; U2SP;

VPSP) as a suggestion to a user.

133. The method according to any preceding example, further comprising delivering a signal to a regulator to change the operation of the pump to correspond to the determined operation parameter (Ul, FROT; U2SP; VPSP).

134. The method according to any preceding example, wherein adjusting the volume of the adaptive volute occurs during operation of the pump.

135. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is based on a time of occurrence of said fluid pressure pulsation event (Sp(r)) and a time of occurrence of said rotational reference position. 136. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is based on time of occurrence of said fluid pressure pulsation event (Sp(r)) and at least two times of occurrence of a rotational reference position.

1 7. A computer program product comprising a non-transitory computer-readable storage medium having thereon a computer program comprising program instructions, the computer program being loadable into one or more processors and configured to cause the one or more processors to perform the method according to any one of the preceding examples.

138. A system for operating a centrifugal pump (10), the system being configured to perform the method according to any preceding example.

139. The system according to example 138, further comprising one or more hardware processors configured to perform the method according to any preceding example.

140. The system according to example 138 or 139, further comprising a centrifugal pump having: an impeller; and an adaptive casing (62A) forming an adaptive volute (75A) in which the impeller is disposed, the adaptive casing (62A) having an inlet for receiving fluid from an outside environment and an outlet for discharging out of the adaptive volute fluid impelled by the impeller, the adaptive casing (62A) being configured to adjust a volute volume based on the determined at least one operating parameter.

141. A centrifugal pump (10) having a casing forming a volute (75; 75A) in which a rotatable impeller (20) is disposed for urging a fluid material (30) into the volute thereby causing a fluid pressure pulsation (PFP); the centrifugal pump comprising

- a sensor for generating a signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP).

142. The centrifugal pump (10) according to any preceding example, wherein said sensor (70, 70₇₈, 70??) is attached to a casing (62) of the pump.

143. The centrifugal pump (10) according to any preceding example, wherein said sensor (70, 70₇₈, 70??) mounted on a casing (62) of the pump for generating a measuring signal (SEA, SMD, Se(i), S(j), S(q)) dependent on fluid material pressure pulsation (PFP).

144. The centrifugal pump (10) according to any preceding example, wherein said sensor (70, 70₇₈, 70??) comprises an accelerometer.

145. The centrifugal pump (10) according to any preceding example, wherein said sensor (70, 70₇₈, 70??) comprises an accelerometer including a Micro ElectroMechanical System (MEMS) configured to generate said signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP).

146. The centrifugal pump (10) according to any preceding example, wherein said sensor (70, 70₇₈, 70??) comprises a semiconductor silicon substrate configured as a MEMS accelerometer.

147. The centrifugal pump (10) according to any preceding example, wherein said sensor (70, 70₇₈, 70??) comprises a piezo-electric accelerometer configured to generate said signal (SFI P; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP).

148. The centrifugal pump (10) according to any preceding example, wherein said sensor (70, 70₇₈, 70??) is piezoresistive sensor configured to generate said signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP).

149. The centrifugal pump (10) according to any preceding example, wherein said sensor (70, 70₇₈, 70??) is a velocity sensor configured to generate said signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP).

150. The centrifugal pump (10) according to any preceding example, wherein said sensor (70, 70₇₈, 70??) includes a coil and magnet arrangement configured to generate a velocity signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP).

151. The centrifugal pump (10) according to any preceding example, further comprising a position marker device (180) for causing a position sensor (170) to generate an impeller revolution marker signal (EP; Ps).

151. The centrifugal pump (10) according to any preceding example, wherein said position marker device (180) is provided in association with the impeller (20) such that, when the impeller (20) rotates around an axis of rotation (60), a position marker (180) passes by a position sensor (170) at least once per revolution of the impeller.

152. The centrifugal pump (10) according to any preceding example, wherein said position marker device (180) comprises a reflective tape (180) attached on a rotating part associated with the pump.

153. The centrifugal pump (10) according to any preceding example, further comprising a position sensor (170) for generating a position signal (EP, PS, P(i), P(j), P(q) ) in cooperation with said position marker device (180).

154. The centrifugal pump (10) according to any preceding example, wherein said position sensor (170) comprises a light source (170), such as e.g. a laser light source.

155. The centrifugal pump (10) according to any preceding example, wherein said position sensor (170) comprises a light source (170) for generating a position signal (EP, PS, P(i), P(j), P(q) ) in cooperation with said reflective tape (180).

156. The centrifugal pump (10) according to any preceding example, wherein said position marker device (180) comprises a metal part (180) or a magnetic part

(180). 157. The centrifugal pump (10) according to example 156, wherein said position sensor (170) comprises an inductive probe (170) that is configured to detect the presence of said metal part (180) or a magnetic part (180).

158. The centrifugal pump (10) according to any preceding example, wherein said position sensor (170) comprises a Hall effect sensor (170) for generating said position signal (EP, PS, P(i), P(j), P(q) ).

159. The centrifugal pump (10) according to any preceding example, wherein said position marker device (180) is mounted on a shaft connected to the impeller (20).

160. A centrifugal pump arrangement (5; 10; 730; 780; 720) comprising a centrifugal pump (10) according to any preceding example.

161. The centrifugal pump arrangement (730; 780; 720) according to example 160 further comprising:

- a first centrifugal pump arrangement data port (800, 820), connectable to a communications network;

- a first centrifugal pump arrangement communications device (790) being configured to deliver, via said first centrifugal pump arrangement data port (820): data indicative of said measuring signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)).

162. The centrifugal pump arrangement (730; 780; 720) according to example 160 further comprising:

- a first centrifugal pump arrangement communications device (790) being configured to deliver, via said first centrifugal pump arrangement data port (820): data indicative of said measuring signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)), and data indicative of said position signal (Ep, P(i), P(j), P(q)).

163. The centrifugal pump arrangement (730; 780; 720) according to example 160 further comprising: - a sensor for generating a signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP).

- a position sensor for generating a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said impeller, and

164. The centrifugal pump arrangement according to any preceding example, wherein said communications network comprises the world wide internet, also known as the Internet.

165. The centrifugal pump arrangement according to any of examples 161 to 164, further comprising:

- a second centrifugal pump arrangement data port (800B; 820B), connectable to a communications network;

- a second centrifugal pump arrangement communications device (790B) being configured to receive, via said second centrifugal pump arrangement data port (800B; 820B): data (FI; Xl(r); X2, Sp(r); X5, fROT) indicative of an internal state of said centrifugal pump.

165. The centrifugal pump arrangement according to any preceding example, further comprising:

- a second centrifugal pump arrangement communications device (790B) being configured to receive, via said second centrifugal pump arrangement data port (800B; 820B): data (Rr(r); TD; FI(r); Xl(r); X2, Sp(r), f_ROT, dR?(r); d Sp(r)) indicative of an operating point (205) of said centrifugal pump. 166. The centrifugal pump arrangement according to any preceding example, further comprising: a Human Computer Interface (HCI; 210) for enabling user input/output; and a screen display (210S); and wherein said Human Computer Interface (HCI; 210) is configured to display, on said screen display (210S), data (FI; Xl(r); X2, Sp(r); X5, fROT) indicative of said internal state (X) of said centrifugal pump.

167. The centrifugal pump arrangement according to any preceding example, further comprising: a Human Computer Interface (HCI; 210) for enabling user input/output; and a screen display (210S); and wherein said Human Computer Interface (HCI; 210) is configured to display, on said screen display (210S), data (FI; Xl(r); X2, Sp(r); X5, fROT) indicative of an operating point (205) of said centrifugal pump.

168. The centrifugal pump arrangement according to any preceding example, wherein: the second centrifugal pump arrangement communications device (790B) is said first centrifugal pump arrangement communications device (790) and said second centrifugal pump arrangement data port (800B; 820B) is said first centrifugal pump arrangement data port (820).

169. The centrifugal pump arrangement according to any preceding example, further comprising: a control module (150, 150B) configured to receive said data (FI; Xl(r); X2, Sp(r); X5, fROT) indicative of an internal state of said centrifugal pump.

170. The centrifugal pump arrangement according to any preceding example, wherein: said control module (150, 150B) includes

- a regulator (755) configured to control a rotational speed (Ul, fROT) of the impeller (20) based on said data (FI; XI (r); X2, Sp(r); X5, fROT) indicative of an internal state of said centrifugal pump; and/or - a regulator configured to control the rotational speed (f_ROT) of the impeller (20) based on said data (FI; XI (r); X2, Sp(r); X5, fROT) indicative of an internal state of said centrifugal pump; and/or

- a regulator configured to control an adjustable volute volume of said centrifugal pump based on said data (FI; XI (r); X2, Sp(r); X5, fROT) indicative of an internal state of said centrifugal pump.

171. The centrifugal pump arrangement according to any preceding example, wherein: said control module (150, 150B) includes

- a regulator (755) configured to control a rotational speed (Ul, fROT) of the impeller (20) based on said value (FI(r)) indicative of an operating point (205) of said centrifugal pump, and/or

- a regulator configured to control an adjustable volute volume of said centrifugal pump based on said value (FI(r)) indicative of an operating point (205) of said centrifugal pump.

172. A monitoring apparatus (870; 880; 150; 150A) for cooperation with a centrifugal pump arrangement according to any preceding example, or according to any of examples 160 to 171, the monitoring apparatus comprising:

- a monitoring apparatus data port (920, 920A), connectable to a communications network (810), for data exchange with a centrifugal pump arrangement; wherein

- said monitoring apparatus (870; 880; 150; 150A) is configured to receive, via said monitoring apparatus data port (920, 920 A): data indicative of a measuring signal (SFIMP; SE , SMD, Se(i), S(j), S(q)), and data indicative of a position signal (Ep, P(i), P(j), P(q)); the monitoring apparatus (870; 880; 150; 150A) further comprising: a status parameter extractor (450) being configured to generate data

(FI; XI (r); X2, Sp(r); X5, fROT) indicative of an internal state of said centrifugal pump based on said measuring signal and said position signal. 173. A monitoring apparatus (870; 880; 150; 150A) for cooperation with a centrifugal pump arrangement according to any preceding example, or according to any of examples 160 to 171, the monitoring apparatus comprising:

- said monitoring apparatus (870; 880; 150; 150A) is configured to receive, via said monitoring apparatus data port (920, 920 A): data indicative of a measuring signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)); the monitoring apparatus (870; 880; 150; 150A) further comprising: a status parameter extractor (450) being configured to generate data (FI(r); XI (r); X2, Sp(r); X5, fRo?) indicative of an internal state of said centrifugal pump based on said measuring signal.

174. The monitoring apparatus according to any preceding example, wherein: said monitoring apparatus (870; 880; 150; 150A) is configured to transmit, via said monitoring apparatus data port (920, 920A): generated data (FI; Xl(r); X2, Sp(r); X5, fROT) indicative of said internal state of said centrifugal pump to said centrifugal pump arrangement.

175. The monitoring apparatus according to any preceding example, wherein said monitoring apparatus (870; 880; 150; 150A) is configured to generate and transmit a value (R (r); TD; FI(r)) indicative of an operating point (205) of said centrifugal pump to said centrifugal pump arrangement.

176. An assembly for cooperation with a centrifugal pump arrangement according to any preceding example, or according to any of examples 160 to 171, the assembly comprising: a monitoring module (150; 150A), a control module (150; 150B), and at least one assembly data port (920, 920A, 920B), connectable to a communications network (810), for data exchange with a centrifugal pump arrangement; wherein said monitoring module (150; 150A) is configured to receive, via said assembly data port (920, 920A): data indicative of a measuring signal (SFIMP; SEA, SMD, Se(i), S(j), S(q)), and data indicative of a position signal (Ep, P(i), P(j), P(q)); the monitoring module (150; 150A) being configured to generate data (FI; Xl(r); X2, Sp(r); X5, fROT) indicative of an internal state of said centrifugal pump based on said measuring signal and said position signal, said control module (150; 150B) is arranged to communicate with said centrifugal pump arrangement via an assembly data port (920, 920B), and said control module (150, 150B) includes

- a regulator (755) configured to control a rotational speed (Ul, fROT) of the impeller (20) based on said data (TD; FI(r); R-r(r); XI (r); X2, Sp(r); X5, FROT) indicative of an internal state of said centrifugal pump; and/or

177. The assembly according to any preceding example, wherein the assembly is arranged at a location geographically distant from said centrifugal pump (10).

178. The system according to any preceding example or the monitoring apparatus according to any preceding example or the centrifugal pump arrangement according to any preceding example, wherein a vibration sensor is attachable to a pump for generating said measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)); said vibration sensor being configured to generate said measuring signal based on vibration (VFP) exhibited by said pump; and/or a strain gauge is attachable to a pump casing (62) or to a pump outlet pipe (54) for generating said measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)); said strain gauge being configured to generate said measuring signal based on deformation, caused by fluid pressure pulsation (PFP ), of said pump casing (62) or of said pump outlet pipe (54); and/or a pressure sensor for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) is mountable so as to detect a fluid pressure pulsation (PFP ) in said fluid material (30).

179. The method according to any preceding example, wherein said measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) is generated by a vibration sensor configured to generate said measuring signal based on vibration (VFP) exhibited by said pump; and/or said measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) is generated by a strain gauge configured to generate said measuring signal based on deformation, caused by fluid pressure pulsation (PFP ), of a pump casing (62) or of a pump outlet pipe (54); and/or said measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) is generated by a pressure sensor configured to detect a fluid pressure pulsation (PFP, P54) in said fluid material (30).

180. A method of operating a centrifugal pump (10) having a casing forming an adaptive volute (75A) having an adjustable volume in which a rotatable impeller (20) is disposed for urging a fluid material (30) into the volute, the method comprising:

- monitoring a fluid pressure pulsation event inside the pump casing;

- generating, based on said monitoring, a measuring signal indicative of occurrence of said first fluid pressure pulsation event;

- determining a temporal relation value (Fl, FI(r)) based on time of occurrence of said fluid pressure pulsation event (Sp(r)) and said reference signal;

- controlling said adjustable volute volume based on the determined temporal relation value (Fl, FI(r), U2SP; VPSP).

181. The method according to any preceding example or according to example 179, further comprising determining an operation parameter of the pump based on the determined temporal relation value (FI, FI(r)); wherein the operation parameter comprises a volute set point value (U2SP; VPSP) for controlling said adjustable volute volume.

182. The method according to any preceding example or according to example 181, further comprising generating an operating point error value (FIERRW ) based on an operating point reference value (FIREFW ), and said first temporal relation (R (r); TD; FI(r)), wherein said operation parameter is based on said operating point error value (FlERR(r) ).

Examples 183 - 190: (not included, deliberately left blank).

191. A method of analysing, during operation, a centrifugal pump (10) having a casing forming a volute (75, 75A) in which a rotatable impeller (20) with a first number (L) of vanes (310) is disposed for urging a fluid material (30) into the volute, thereby causing a fluid pressure pulsation, the method comprising: receiving a plurality of measuring signal data values, obtained based on sampling of a signal from a vibration sensor being responsive to the fluid pressure pulsation; receiving a plurality of reference signal data values, obtained by a position sensor, indicative of at least one rotational reference position of said rotating impeller in relation to said casing; providing a digital measuring signal based on said plurality of measuring signal data values at a first input of a Fast Fourier Tranformer (FFT; 510), and providing a reference signal based on said plurality of reference signal data values at a second input of said Fast Fourier Tranformer (FFT; 510), wherein said Fast Fourier Tranformer (FFT; 510) is configured to generate a certain phase angle value (FI(r), (r), O (r) ) based on said digital measuring signal and said reference signal; said certain phase angle value (FI(r), <X>(r), <t>i.(r) ) being indicative of a current state of operation of the centrifugal pump (10).

192. A method of analysing or operating a centrifugal pump (10) having a casing forming a volute (75, 75 A) in which a rotatable impeller (20) with a first number (L) of vanes (310) is disposed for urging a fluid material (30) via the volute to a pump outlet (66), thereby causing a fluid pressure pulsation, the method comprising: receiving a plurality of measuring signal data values, obtained based on sampling of a signal from a vibration sensor being responsive to the fluid pressure pulsation; receiving a plurality of reference signal data values, obtained by a position sensor, indicative of at least one rotational reference position of said rotating impeller in relation to said casing; providing a digital measuring signal based on said plurality of measuring signal data values at a first input of a Fast Fourier Tranformer (FFT; 510), and providing a reference signal based on said plurality of reference signal data values at a second input of said Fast Fourier Tranformer (FFT; 510), wherein said Fast Fourier Tranformer (FFT; 510) is configured to generate a certain phase angle value (FI(r), d>(r), i.(r) ) based on said digital measuring signal and said reference signal; said certain phase angle value (FI(r), (r), <I>L(r) ) being indicative of a current state of operation of the centrifugal pump (10).

193. The method according to example 191 or 192, wherein said Fast Fourier Tranformer (FFT; 510) is configured such that when said Fast Fourier Tranformer (FFT; 510) receives a position reference signal (P(j), P(q)) once per revolution of the rotatable impeller (20), then said Fast Fourier Tranformer (FFT; 510) generates a phase angle value (FI(r), C>(r), d>t(r) ) for a measuring signal whose repetition frequency fR is the frequency of order L, wherein L is the number of vanes (310) in the rotatable impeller (20).

194. The method according to example 191 or 192, wherein said Fast Fourier Tranformer (FFT; 510) is configured such that when said Fast Fourier Tranformer (FFT; 510) receives a position reference signal (PG), P(q)) once every 360/L degrees during a revolution of the impeller (20) and L is equal to said first number of vanes (310) in the impeller (20), then said Fast Fourier Tranformer (FFT; 510) generates a phase angle value (FI(r), (r), i (r) ) for a measuring signal whose repetition frequency fR is equal to the repetition frequency (360/L degrees) of said position reference signal (PG), P(q)).

195. A method of analysing or operating a centrifugal pump (10) having a casing forming an adaptive volute (75, 75A) having an adjustable volume in which a rotatable impeller (20) is disposed for urging a fluid material (30) into the adaptive volute, thereby causing a fluid pressure pulsation, the method comprising: receiving a plurality of measuring signal data values, obtained based on sampling of a signal from a vibration sensor, responsive to the fluid pressure pulsation; receiving a reference signal, obtained by a position sensor, indicative of at least one rotational reference position of said rotating impeller in relation to said casing; determining at least two times of occurrence of at least one rotational reference position; determining time of occurrence of at least one fluid pressure pulsation event (Sp(r)); determining a temporal relation value (FI, FI(r)) based on said time of occurrence of said fluid pressure pulsation event (Sp(r)) in relation to said at least two times of rotational reference position occurrences.

196. A method for monitoring an internal state (X; XI, X2; FI(r), Sp(r)) of a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the rotatable impeller (20) having a first_number (L) of vanes for urging, when the rotatable impeller (20) rotates, a fluid material (30) from a pump inlet (66) into a volute (75), thereby causing a fluid material pulsation (PFP) having a repetition frequency (f ) dependent on a speed of rotation (f_ROT) of the impeller (20); wherein said first number (L) is higher than one; the method comprising receiving, by a monitoring apparatus (150), a vibration signal (SFP; SEA, SMD, Se(i), S(j), S(q)) dependent on the fluid material pulsation ( EP); receiving, by said monitoring apparatus (150), a signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing; detecting, by said monitoring apparatus (150), a first occurrence of a first reference position signal value (1; 1C, 0%) in a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution; said certain number (L) being equal to said first number (L); detecting, by said monitoring apparatus (150), a second occurrence of a second reference position signal value (1; 1 C; 100%) in said time sequence of position signal sample values (P(i), PG), P(q)); detecting, by said monitoring apparatus (150), a third occurrence of an event signature (Sp(r); Sp) in a time sequence of vibration sample values (Se(i), S ), S(q)); said event signature (Sp(r); Sp) being a vibration signal amplitude peak value (Sp(r); Sp, SFP) indicative of a fluid pressure (P54, +, -) generated when the rotating impeller (20) interacts with said fluid material (30); wherein said vibration signal amplitude peak value (Sp(r); Sp, SFP) is repetitive with a first frequency (fp) of one vibration signal amplitude peak value (Sp(r); Sp, SFP) per vane (310); said fluid material pulsation repetition frequency (fp) being equal to said first frequency (fp); generating, by said monitoring apparatus (150), data indicative of a first duration between said first occurrence and said second occurrence; and generating, by said monitoring apparatus (150), data indicative of a second duration between said first occurrence and said third occurrence or data indicative of a second duration between said third occurrence and said second occurrence; generating, by said monitoring apparatus (150), data indicative of a temporal relation value (FI(r), XI, Rr(r); TD) between said second duration, and said first duration.

197. The method according to any preceding example, wherein said temporal relation value (FI(r), XI, R-p(r); TD) is indicative of a deviation (FIoEv(r- 1), FIDEV(P+1) ) of a current operating point (205, 550) from a best efficiency point of operation (BEP, 550BEP) of said centrifugal pump (10).

198. The method according to any preceding example, further comprising generating, by said apparatus (150), said position reference value (1 ; 1C, 0%; 100%) based on said position signal (EP, P(i), P(j), P(q)) such that said position reference value (1; 1C, 0%; 100%) is provided a first number (L) of times per revolution of said rotatable impeller (20), said first number (L) of position reference values (1 ; 1C, 0%; 100%) being indicative of a first number (L) of predetermined rotational positions of said rotatable impeller (20); or generating, by said apparatus (150), said time sequence of position signal sample values (P(i), P(j), P(q)) based on said received position signal (Ep, P(i), P(j), P(q)) such that said time sequence of position signal sample values (P(i), P(j), P(q)) includes a certain number (L) of position reference values (1; 1C, 0%; 100%) per impeller revolution; said certain number (L) being equal to said first number (L).

199. The method according to any preceding example, further comprising: conveying, to a user interface (210, 210S) information indicative of said temporal relation value (FI(r), XI, Rr(r); TD). 200. The method according to any preceding example, wherein said temporal relation value (FI(r), XI, Rr(r); TD) is indicative of a first polar angle (FI(r); XI ; Rr(r); TDI); the method further comprising: representing said internal state (X; XI, X2; FI(r), Sp(r)) of said centrifugal pump (10) on a screen display (210S), said representing comprising: displaying on said screen display (210S) a polar coordinate system (520), said polar coordinate system (520) having a reference point (530, O), and a reference direction (0,360); and a first internal status indicator object (550, SPI, TDI), indicative of said current operating point (205, 550; XI, X2; FI(r), Sp(r)), at said first polar angle (FI(r); XI; Rr(r); TDI) in relation to said reference direction (0,360), and/or at said first polar angle (FI(r); XI; Ri-(r); TDI) in relation to said reference direction (0,360) and at first radius (Sp(r), X2) from said reference point (530, O); wherein said first radius (Sp(r), X2) depends on said vibration signal amplitude peak value (Sp(r); Sp, SFP)

201. A method for monitoring and/or operating a centrifugal pump (10; 10A; 10B; 10C; 10D) having a casing forming a volute (75) in which a rotatable impeller (20) is disposed for urging a fluid material (30) into the volute, the method comprising: receiving a measuring signal indicative of a fluid pressure pulsation (PFP) in the fluid material (30); receiving a reference signal indicative of a rotational reference position (Ps, Pc) of said rotating impeller; generating a temporal relation value (FI, FI(r), X 1 (r)) based on said measuring signal and said reference signal such that said temporal relation value (FI, FI(r), X 1 (r)) is indicative of a current operating point (205, 550; XI (r)) of the centrifugal pump (10). 202. A method for monitoring and/or operating a centrifugal pump (10; 10A; 10B; 10C;

10D) having a casing forming a volute (75) in which a rotatable impeller (20) is disposed for urging a fluid material (30) into the volute, the method comprising: receiving a measuring signal indicative of a fluid pressure pulsation (PFP) in the fluid material (30); receiving a reference signal indicative of a rotational reference position of said rotating impeller; generating data indicative of an internal state of the centrifugal pump, said data including a phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)) based on said measuring signal and said reference signal.

203. The method of example 201 or 202, further comprising determining an operation parameter of the pump based on the determined temporal relation value (FI, FI(r)).

204. The method of example 203, wherein the operation parameter comprises a rotation speed set point value (UISP, FROTSP) for controlling a rotational speed (Ul, fpoi) of the impeller (20).

205. The method according to any preceding example or according to example 203, wherein said volute is an adaptive volute (75) having an adjustable cross sectional area, and the operation parameter comprises a volute set point value (U2SP; Vpsp) for controlling said adjustable cross sectional area.

206. The method according to any preceding example, wherein said volute is an adaptive volute (75) having a first adjustable cross sectional area (A77) , and a second adjustable cross sectional area (A78) wherein the operation parameter comprises a volute set point value (U2SP; VPSP) for simultaneously controlling said first and second adjustable cross sectional areas.

207. The method according to any preceding example, wherein said volute is an adaptive volute (75) having an adjustable volume and/or an adjustable cross sectional area, and wherein the operation parameter comprises a volute set point value (U2SP; VPSP) for controlling said adjustable volute volume and/or said adjustable cross sectional area.

208. A method for monitoring and/or operating a pump (10; 10A; 10B; 10C; 10D) having a casing in which a rotatable part (20, 2000) is disposed for urging a fluid material (30) from an inlet to an outlet, the method comprising: receiving a measuring signal indicative of a vibration in the casing and/or a fluid pressure pulsation (PFP) in the fluid material (30); receiving a reference signal indicative of a rotational reference position of said rotating part (20, 2000); generating data indicative of an internal state of the pump, said data including a phase value (FI, FI(r), XI (r)) and/or a temporal relation value (FI, FI(r), X 1 (r)) based on said measuring signal and said reference signal.

209. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is indicative of an internal state (205, 550, X)) of said centrifugal pump (10).

210. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point (205, 550; X) of the centrifugal pump (10); and/or wherein said phase value (FI, FI(r), X 1 (r)) is indicative of a current operating point (205, 550;

X) of the centrifugal pump (10).

211. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point deviation (FIDEV; FIDEV(P+1); 550(p+l )) from a Best Efficiency Point of operation of the centrifugal pump (10).

212. The method according to any preceding example, further comprising displaying, on a user interface, the determined operation parameter (Ul, fpoTj U2SP;

VPSP) as a suggestion to a user. 213. The method according to any preceding example when including example 203, wherein said volute set point value (U2SP; Vpsp) is based on a desired temporal relation value (FIREF, FlREp(r), XI REF).

214. The method according to any preceding example when including example 203, wherein said volute set point value (U2SP; VPSP) is based on a desired temporal relation value (FIREF, FI_REp(r), XI REF), said desired temporal relation value (FIREF, FIREFC"), XI REF) being indicative of a desired pump operating point (205REF, 550 REF; XI REF (r)).

215. The method according to any preceding example when including example 203, wherein said rotation speed set point value (U 1 SP, FROTSP) is based on a desired impeller rotational speed (UI REF, FROTREF, X3REF).

216. The method according to any preceding example when including example 203, wherein said rotation speed set point value (U I SP, FROTSP) is based on a desired impeller rotational speed (U I REF, FROTREF, X3REF), said desired impeller rotational speed (U I REF, FROTREF, X3REF) being indicative of a desired system flow (Y2REF, QOUT_REF, Q_OUTS REF) and/or a desired system Head (YIREF, P54REF).

217. The method according to any preceding example, wherein adjusting the volume of the adaptive volute occurs during operation of the pump.

218. The method according to any preceding example, wherein said temporal relation value (Xl(r), FI, FI(r)) is based on a time of occurrence of a fluid pressure pulsation event (Sp(r)) in said fluid pressure pulsation (PFP) and a time of occurrence of said rotational reference position.

219. The method according to any preceding example, wherein said temporal relation value (Xl(r), FI, FI(r)) is based on a time of occurrence of a fluid pressure pulsation event (Sp(r)) in said fluid pressure pulsation (PFP) and at least two times of occurrence of a rotational reference position.

220. The method according to any preceding example, wherein said measuring signal is indicative of a pulsation repetition frequency (fp, X4); said pulsation repetition frequency (fp, X4) being a number of occurrences of a repeating event (Sp) in said fluid pressure pulsation (PFP) per time unit; wherein said pulsation repetition frequency (fp, X4) depends on a speed of impeller rotation (1'ROT), and wherein said reference signal is indicative of a reference position repetition frequency (fp, X4); said reference position repetition frequency (fp, X4) being equal to said pulsation repetition frequency (fp, X4).

221. The method according to any preceding example, wherein said measuring signal is indicative of a pulsation repetition frequency (fp, X4); said pulsation repetition frequency (fp, X4) being a number of occurrences per impeller revolution of a repeating event (Sp) in said fluid pressure pulsation (PFP); and wherein said reference signal is indicative of a reference position repetition frequency (fp, X4); said reference position repetition frequency (fp, X4) being a number of occurrences per impeller revolution of a repeating reference position value (Ps, Pc); said reference position repetition frequency (fp, X4) being equal to said pulsation repetition frequency (fp, X4).

222. The method according to any preceding example, wherein said temporal relation value (Xl(r), FI, FI(r)) is indicative of a phase (FI, FI(r)) between said repeating event (Sp) and said repeating reference position.

223. The method according to any preceding example, wherein said reference signal has a first number (L) of reference position values (Ps, Pc) per revolution of said impeller when said rotatable impeller (20) has a first number (L) of vanes.

224. The method according to example 223, further comprising providing said measuring signal to a first input of a Fast Fourier Tranformer (FFT; 510), and providing said reference signal to a second input of said Fast Fourier Tranformer (FFT; 510); and setting said Fast Fourier Tranformer (FFT; 510) such that when said Fast Fourier Tranformer (FFT; 510) receives said reference signal having said first number (L) of reference position values (Ps, Pc) per revolution of said impeller, then said Fast Fourier Tranformer (FFT; 510) generates a phase angle value (FI(r), <t>(r), i(r) ) for a fundamental frequency component of the provided measuring signal, i.e. a phase angle value for a signal of order one (1).

225. The method according to any of examples 221 or 222 or any preceding example, wherein said reference signal has one reference position value (Ps) per revolution of said impeller when said rotatable impeller (20) has a first number (L) of vanes.

226. The method according to example 225, further comprising providing said measuring signal to a first input of a Fast Fourier Tranformer (FFT; 510), and providing said reference signal to a second input of said Fast Fourier Tranformer (FFT; 510); and setting said Fast Fourier Tranformer (FFT; 510) such that when said Fast Fourier Tranformer (FFT; 510) receives said reference signal having one reference position value (Ps) per revolution of said impeller, then said Fast Fourier Tranformer (FFT; 510) generates a phase angle value (FI(r), <P(r), <I>L(r) ) for a frequency component, of the provided measuring signal, of an order that equals said first number (L).

227. The method according to example 225 or 226, wherein when a settable integer value (Oi), on a Fast Fourier Tranformer (FFT; 510), is set to equal to said first number (L), then said Fast Fourier Tranformer (FFT; 510) generates a phase angle value (FI(r), (r), ®i (r) ) for a certain harmonic partial of said measuring signal, said certain harmonic partial being a harmonic partial of an order that equals said first number (L). 228. The method according to any preceding example or according to any of examples 220 to 223, wherein said measuring signal includes a time sequence of measurement sample values (Se(i), S(j), S(q)); said measurement sample value time sequence being indicative of a pulsation repetition frequency (fR, X4); said pulsation repetition frequency (fR, X4) being a number of occurrences of a repeating event (Sp) in said fluid pressure pulsation (PFP) per time unit; wherein said pulsation repetition frequency (fR, X4) depends on a speed of impeller rotation (I'ROT), and wherein said reference signal includes a time sequence of position signal sample values (P(i), P(j), P(q)); said position signal sample value time sequence being indicative of a reference position repetition frequency (fR, X4); said reference position repetition frequency (fR, X4) being equal to said pulsation repetition frequency (fR, X4).

229. The method according to any preceding example, further comprising: recording or storing, in a memory, said time sequence of measurement sample values (Se(i), S(j), S(q)), and recording or storing, in a memory, said time sequence of position signal sample values (P(i), PG), P(q)), and recording or storing, in a memory, time information (i, dt; j; q) such that an individual measurement sample value (S )) is associated with data indicative of time of occurrence of the individual measurement data value (SG)) in relation to time of occurrence of an individual position signal value (P(i)).

230. The method according to any preceding example, further comprising: recording or storing, in a memory, said time sequence of measurement sample values (Se(i), SG), S(q), S(t)), and recording or storing, in a memory, said time sequence of position signal sample values (P(i), PG), P(q), P(t)), and recording or storing, in a memory, time information (i, dt; j, t), relating to said measurement sample values and relating to said position signal sample values, such that said measurement sample values (Se(i), SG), S(q), S(t)) are time synchronized with said position signal values (P(i), PG), P(q), P(t)). 231. The method according to any preceding example or according to any of examples 229 to 230, further comprising generating (500; SI 40) a speed value (FROT) indicative of a speed of rotation of said impeller (20); associating said speed value (f_ROT) with a time slot (i; j; q) such that an individual measurement sample values (Se(i), S(j), S(q)) is associated with a speed value (fRoi(i), fROT(j), fRor(q), fRor(t)).

232. The method according to any preceding example or according to any of examples 229 to 230, further comprising generating (500; SI 40) a speed value (f_ROT) indicative of a speed of rotation of said impeller (20); associating said speed value ((ROT) with a time slot (i; j; q) such that an individual measurement sample values (Se(i), S(j), S(q)) is associated with a speed value (fRoi(i), fRo?(j), fRO-r(q), fRO-r(t)); wherein said speed value (fRor(i), fuorG), fROT(q), fROT(t)) is based on

- said measurement sample values,

- said position signal sample values (P(i), P(j), P(q)), and

- said time information (i, dt; j).

233. The method according to any preceding example or according to any of examples 231 to 232, wherein a said speed value (fRor(i), f_ROT(j), fROT(q), fRoi(t)) is generated by interpolation.

234. The method according to any preceding example or according to any of examples 229 to 232, further comprising: recording or storing, in a memory, said time sequence of measurement sample values (Se(i), S(j), S(q), S(t)), and recording or storing, in a memory, said time sequence of position signal sample values (P(i), P(j), P(q), P(t)), and recording or storing, in a memory, a time sequence of speed values (fRoi(i), fRorCX fRor(q), fRor(t)) relating to said measurement sample values such that a said measurement sample value (Se(i), S(j), S(q), S(t)) is associated with a corresponding speed value (fROT(i), fROT0), fROT(q), fROT(t)).

235. The method according to any preceding example or according to any of examples 229 to

234, further comprising: generating a decimated digital measurement signal (SMDR) such that the decimated number (Nv) of measurement sample values (S(q)) per revolution of said rotating impeller is kept at a constant value, or at a substantially constant value when said rotational speed varies.

236. The method according to any preceding example or according to any of examples 234 to

235, further comprising: generating a decimated digital measurement signal (SMDR, S(q)) such that the decimated number (Nv) of measurement sample values per revolution of said rotating impeller is kept at a constant value, or at a substantially constant value when said rotational speed varies; wherein said decimated digital measurement signal (SMDR) is generated based on said recorded time sequence of measurement sample values (Se(i), S(j), S(q)), said recorded time sequence of position signal sample values (P(i), P(j), P(q),

P(t)), and said recorded time sequence of speed values (fRor(i), fROT(j), fRor(q), fROT(t)).

237. The method according to any preceding example or according to any of examples 234 to

236, further comprising: generating another digital measurement signal (STSA); said another digital measurement signal (STSA) including a reduced number (Nv) of position specific measurement sample values per revolution of said rotating impeller; wherein a position specific measurement sample value is based on several, at least two, decimated measurement signal sample values (S(q)) that are indicative of the same rotational position or position along the path of the cycle.

238. The method according to any preceding example or according to any of examples 234 to

237, further comprising: generating another digital measurement signal (STSA); said another digital measurement signal (STSA) including a reduced number (Nv) of position specific measurement sample values per revolution of said rotating impeller; wherein a position specific measurement sample value (STSAO) is generated as:

wherein

M is the number of impeller revolutions to be averaged, and

Nv is the number of measurement sample values per revolution of the rotating impeller.

239. The method according to any preceding example or according to any of examples 229 to 234, further comprising: generating a decimated digital measurement signal (SMDR) such that the decimated number (Nv) of measurement sample values (S(q)) occurring between two mutually adjacent position signal sample values (P(i), P(j), P(q), P(t)) is kept at a constant value, or at a substantially constant value when said rotational speed varies; and delivering a decimated measurement sample value (S(q)) in association with a corresponding rotational speed value (fRoi(q), X3(q)); wherein said decimated digital measurement signal (SMDR) is generated, by a compensatory decimator (470, 470B), based on said recorded time sequence of measurement sample values (Se(i), S(j)), said recorded time sequence of position signal sample values (P(i), P(j)), and said recorded time sequence of speed values (fRor(i), fROT(j)).

240. The method according to any preceding example or according to any of examples 229 to 234, further comprising: generating a decimated digital measurement signal (SMDR) such that the decimated number (Nv) of measurement sample values (S(q)) occurring between two mutually adjacent position signal sample values (P(i), P(j), P(q), P(t)) is kept at a constant value, or at a substantially constant value when said rotational speed varies, and delivering (470B) a decimated measurement sample value (S(q)) in association with a corresponding rotational speed value (f_ROT(q), X3(q)). 241. The method according to any preceding example or according to any of examples 239 to 240, further comprising: generating another digital measurement signal (STSA); said another digital measurement signal (STSA) including a reduced number (Nv) of position specific measurement sample values per revolution of said rotating impeller; wherein a position specific measurement sample value is based on several, at least two, decimated measurement signal sample values (S(q)) that are indicative of the same rotational position or same position along a path of a cycle between two adjacent reference positions (Ps, Pc).

242. The method according to any preceding example or according to any of examples 239 to

240, further comprising: generating another digital measurement signal (STSA); said another digital measurement signal (STSA) including a reduced number (Nv) of position specific measurement sample values per revolution of said rotating impeller; wherein a position specific measurement sample value is based on decimated measurement signal sample values (S(q)), and a position specific measurement sample value (STSA(9) is generated as:

wherein

M is the number of impeller revolutions to be averaged, and

Nv is the number of measurement sample values per revolution of the rotating impeller, and wherein M is equal to, or larger than, two (2).

The another digital measurement signal (STSA) advantageously has a reduced noise level. The reduced noise level is obtained because position specific measurement sample values are obtained. This is possible because the inventor realized that the pulsation event is repetitive in such a manner that noise levels can be reduced by collection of samples over a number M of revolutions and by the above described method of generating position specific measurement sample values. An individual position specific measurement sample value therefore is an average of measured sample values collected for that individual rotational position over the course of M revolutions. 243. The method according to any preceding example, wherein said reference signal has a first number (L) of reference position values (Ps, Pc) per revolution of said impeller when said rotatable impeller (20) has a first number (L) of vanes.

244. The method according to example 223 when dependent on any of examples 241 - 243, further comprising providing said another digital measurement signal (STSA, S(q)) to a first input of a Fast Fourier Tranformer (FFT; 510), and providing said reference signal ((P(q)) to a second input of said Fast Fourier Tranformer (FFT; 510); and setting said Fast Fourier Tranformer (FFT; 510) such that when said Fast Fourier Tranformer (FFT; 510) receives said reference signal ((P(q)) having said first number (L) of reference position values (Ps, Pc) per revolution of said impeller, then said Fast Fourier Tranformer (FFT; 510) generates a phase angle value (FI(r), <b(r), i(r) ) for a fundamental frequency component of the provided another digital measurement signal (STSA, S(q)), i.e. a phase angle value for a signal of order one (1).

245. The method according to any preceding example or according to any of examples 241 to 242, wherein said reference signal has one reference position value (Ps) per revolution of said impeller when said rotatable impeller (20) has a first number (L) of vanes.

246. The method according to example 245, further comprising providing said another digital measurement signal (STSA, S(q)) to a first input of a Fast Fourier Tranformer (FFT; 510), and providing said reference signal to a second input of said Fast Fourier Tranformer (FFT; 510); and setting said Fast Fourier Tranformer (FFT; 510) such that when said Fast Fourier Tranformer (FFT; 510) receives said reference signal having one reference position value (Ps) per revolution of said impeller, then said Fast Fourier Tranformer (FFT; 510) generates a phase angle value (FI(r), (r), i (r) ) for a frequency component, of the provided another digital measurement signal (STS , S(q)), of an order that equals said first number (L).

247. The method according to example 245 or 246, wherein when a settable integer value (Oi), on a Fast Fourier Tranformer (FFT; 510), is set to equal to said first number (L), then said Fast Fourier Tranformer (FFT; 510) generates a phase angle value (FI(r), (r), >L(r) ) for a certain harmonic partial of said measuring signal, said certain harmonic partial being a harmonic partial of an order that equals said first number (L).

248. The method according to any of examples 201 to 234 or according to any preceding example, further comprising detecting (980, 1010) a first occurrence of a first reference position signal value (1; 1C, 0%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting (980, 1010) a second occurrence of a second reference position signal value (1; 1C; 100%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting (990, 1020) a third occurrence of an event signature (Sp(r); Sp) in said time sequence of measurement sample values (Se(i), S(j), S(q)); generating (1010), based on said time sequence of position signal sample values (P(i); P(j); P(q)), data indicative of a reference duration (TREFI) between said first occurrence (1; 1C, 0%, 0°, Pc) and said second occurrence (1; 1C, Pc, 100%, 360°); and generating (1020), based on time information (i, dt; j, t) relating to said third occurrence and time information (i, dt; j, t) relating to said time sequence of position signal sample values, data indicative of an event phase duration value (TEPD); said event phase duration value (TEPD) being indicative of time between said first occurrence (1; 1C, 0%, 0°, Pc) and said third occurrence (Sp(r); Sp), or said event phase duration value (TEPD) being indicative of time between said third occurrence (Sp(r); Sp) and said second occurrence (1; 1C, Pc, 100%, 360°); and generating (1050) data indicative of a first temporal relation (XI; FI(r), (r)) between said event phase duration value (TEPD) and said reference duration (TREFI).

249 A. The method according to any preceding example when dependent on example 208, wherein said casing forms a chamber in which said rotatable part (2000) is disposed for rotating around an axis (60 ); said axis (60 ) being offset in relation to a center of said chamber.

249 B. The method according to any preceding example when dependent on example 208, wherein said fluid material (30) is in a gaseous phase, said rotatable part (2000) is an impeller (20); and said casing forms a chamber in which said rotatable impeller (20, 2000) disposed for rotating around an axis (60 ); said axis (60 ) being offset in relation to a center of said chamber; and wherein, in operation, said chamber is partly filled with a liquid; and wherein, when said impeller (20) rotates at a speed (fRo?) exceeding a certain limit speed value, said liquid forms a ring so that the pump operates as a liquid ring pump; said liquid ring pump having an inlet for the gaseous material (30) and an outlet for the gaseous material (30).

250. The method according to any preceding example when dependent on example 208, wherein said impeller (20) having a first number (L) of vanes or blades that co-operate with said liquid ring to form compartments; and wherein the compartments (Cl), during operation of the pump, expand when communicating with said inlet so as to cause gaseous material (30) to enter the pump chamber, and wherein the compartments (C3), during operation of the pump, contract when communicating with said outlet so as to cause gaseous material (30) to exit the pump chamber, and wherein a compartment(C2), during operation of the pump, contracts when it does not communicate with said inlet or said outlet. 251 . The method according to any preceding example or the method according to any preceding example when dependent on example 208 and/or any of examples 248-250, further comprising the steps: generate, with a sensor, a measurement signal (SEA) dependent on mechanical movement caused by operation of the pump; generate, with a position sensor, a position signal indicative of a rotational position of said rotating part; record, with a signal recorder,

- a time sequence of measurement sample values (Se(i), S(j)) of said digital measurement signal (SE , SMD), and

- a time sequence of said position signal values (P(i)), and

- time information (i, dt; j) such that an individual measurement sample value (S(j)) is associated with data indicative of time of occurrence of the individual measurement data value (S(j)), and such that an individual position signal value (P(i)) is associated with data indicative of time of occurrence of the individual position signal value (P(i)); detect, with a processor, the occurrence of an event, such as e.g. an amplitude peak value, in said recorded time sequence of measurement sample values (Se(i), S(j)); generate, with a processor, data indicative of an internal state of the pump, said data including a phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl (r)) based on said measuring signal and said reference signal; and/or generate, with a processor, data indicative of said first temporal relation (XI ; FI(r), d>(r)) based on said detected event occurrence and said time sequence of measurement sample values (Se(i), S(j)).

252. A method for monitoring and/or operating a fluid system (52) including a valve arrangement (VL; VH ) for receiving fluid material (30) from a centrifugal pump (10) ; the method including the steps according to any preceding example or according to any of examples 201 to 251.

253. A method for monitoring and/or operating a centrifugal pump (10; 10A; 10B; IOC; 10D) having a casing forming a volute (75) in which a rotatable impeller (20) is disposed for urging a fluid material (30) via the volute to a pump outlet (66) which is coupled to a fluid system (52) via a valve arrangement (VL; VH ), the method comprising: receiving a measuring signal indicative of a fluid pressure pulsation (PFP) in the fluid material (30); receiving a reference signal indicative of a rotational reference position of said rotating impeller; generating data indicative of an internal state of the centrifugal pump, said data including a phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)) based on said measuring signal and said reference signal.

254. The method according to any preceding example or the method according to any of examples 252 or 253 or the method according to any preceding example when dependent on any of examples 201 to 251 , further comprising the steps: generating at least one set point parameter (U I SP, U2SP) based on said phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)); wherein said at least one set point parameter (U I SP, U2SP) comprises a rotation speed set point value (UISP, fROTSp) for controlling a rotational speed (Ul, fRoi) of the impeller (20).

255. The method according to example 254 when dependent on any of examples 252-253, wherein said a valve arrangement (VL; VH) comprises a flow control valve (VL; VH) having a first adjustable cross sectional area (AVLS; AVHS) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said at least one set point parameter (UI SP, U2SP) comprises a first valve set point value (U2SP, U2ASP) for controlling said first adjustable cross sectional area (AVLS; AVHS).

256. The method according to any of examples 252-255, wherein said valve arrangement (VL; VH) comprises a first flow control valve (VLS) having a first adjustable cross sectional area (AVLS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said valve arrangement (VL; VH) comprises a second flow control valve (VLR) having a second adjustable cross sectional area (AVLR ) for controlling another flow (QR), such as for example a return flow (QR); said another flow (QR) being diverted from flowing to the fluid system (52), wherein said at least one set point parameter (UI SP, U2SP) comprises a first valve set point value (U2SP, U2ASP) for simultaneously controlling said first adjustable cross sectional area (AVLS ) and said second adjustable cross sectional area (AVLR ).

257. The method according to any of examples 252-256, wherein the another flow (QOUTR) is a return flow for returning fluid to a fluid storage or to an inlet side of the pump (10).

258. The method according to any of examples 252-257, wherein said phase value (FI, FI(r), X 1 (r)) is indicative of a current operating point of the pump in relation to a Best Efficiency Point of operation, and/or wherein said temporal relation value (FI, FI(r), X 1 (r)) is indicative of a current operating point of the pump in relation to a Best Efficiency Point of operation.

259. The method according to any of examples 252-258, wherein said rotation speed set point value (UISP, f_ROTSP) affects pump outlet fluid pressure (¥1, P54) and/or pump outlet fluid flow (Y2, QOUT) at said pump outlet (66), and wherein said rotation speed set point value (UISP, f_ROTSP) is based on a desired system delivery flow (YI OREF, Q_OUTSREF) and on said phase value (FI, FI(r), X 1 (r)) and/or temporal relation value (FI, FI(r), Xl(r)).

260. The method according to example 256 or any of examples 255-259, wherein said first valve set point value (U2SP, U2ASP) is initially set so that said system delivery flow (Y10, Q_OUTS) is equal to said pump outlet fluid flow (Y2, QOUT), for example by simultaneously controlling said first adjustable cross sectional area (AVLS ) and said second adjustable cross sectional area (AVLR ) so as to direct all, or substantially all, of said pump outlet fluid flow (Y2, QOUT) to said fluid system (52). 261. The method according to example 256 or any of examples 255-260, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow, then said rotation speed set point value (UISP, f_ROT SP) is adjusted to increase said impeller rotational speed (Ul, f_ROT).

262. The method according to example 256 or any of examples 255-261, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow, then said rotation speed set point value (UISP, f_ROTSP) is adjusted to increase said impeller rotational speed (Ul, f_ROT) until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF).

263. The method according to example 256 or any of examples 255-262, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a lower pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow

(Y10, Q_OUTSREF); then said rotation speed set point value (UISP, f_ROTSP) is adjusted to increase said impeller rotational speed (Ul, fROT), e.g. until said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said first valve set point value (U2SP, U2ASP) is adjusted so as to increase said another flow (QR) .

In this manner, for example, an oversized pump that was running at a speed of revolution below BEP flow is operated to increase pump outlet fluid flow (Y2, QOUT), thereby allowing the pump to run at a more energy efficient point of operation 205 at or near BEP flow, and a surplus flow, i.e. a difference between pump outlet fluid flow at BEP (Y2BEP, Q_OUTBEP) and the system delivery flow (Y10, Q_OUTS), may be directed as a return flow. In this manner, the method according to example 263 advantageously enables the delivery of a variable desired system delivery flow (Y10, Q_OUTSREF) while enabling the centrifugal pump to operate at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), thereby reducing or eliminating unfavourable pump operating conditions. Thus, example 263 addresses a problem of how to enable delivery of a variable fluid flow and pressure while reducing or eliminating unfavourable pump operating conditions.

264. The method according to example 256 or any of examples 255-263, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with pump outlet flow (Y2, QOUT) at, or substantially at, Best Efficiency Point of pump outlet flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y10, Q_OUTSREF); then said first valve set point value (U2SP, U2ASP) is adjusted so as to minimize, or eliminate, said another flow (QR).

265. The method according to example 256 or any of examples 255-264, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a flow at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is higher than to a desired system delivery flow (YI OREF, Q_OUTSREF); then said rotation speed set point value (Ulsp, f_ROTSP) is adjusted to decrease said impeller rotational speed (Ul, f_ROT), e.g. until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YI OREF, Q_OUTSREF).

266. The method according to any preceding example or according to example 254 when dependent on any of examples 252-253, wherein said valve arrangement (VL; VH) comprises a flow control valve (VH) having a third adjustable cross sectional area (AVHS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said at least one set point parameter (Ulsp, U2SP) comprises a second valve set point value (U2SP, U2BSP) for controlling said third adjustable cross sectional area (AVHS ). 267. The method according to example 266 or any of examples 255-262, wherein when said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) with a higher pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), then said second valve set point value (U2SP, U2BSP) is adjusted so as to reduce said third adjustable cross sectional area (AVHS )•

It is noted that a reduction of the third adjustable cross sectional area (AVHS ) will cause a reduced pump outlet fluid flow (Y2, QOUT) and an increased pump outlet fluid pressure (Yl, P54). In this manner, for example, a pump that was running at back pressure Y 1 below BEP back pressure (YIBEP) is operated to increase pump outlet fluid pressure (Yl , P54), thereby allowing the pump to run at a more energy efficient point of operation 205 at or near BEP pressure (YIBEP), and a surplus pressure, i.e. a difference between pump outlet fluid pressure (Yl, P54) at BEP (YI BEP) and the system delivery Head (Ps4s), is exhibited as a pressure difference across the flow control valve (VH).

However, it is noted that the resulting reduced pump outlet fluid flow (Y2, QOUT) may render a system delivery flow (Y10, Q_OUTS) to the fluid system (52) that is lower than a desired system delivery flow (YIOREF, Q_OUTSREF).

268. The method according to example 256 or any of examples 255-264, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a flow at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is lower than to a desired system delivery flow (YI OREF, Q_OUTSREF); then said rotation speed set point value (UISP, FROTSP) is adjusted to increase said impeller rotational speed (Ul, TROT), e.g. until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y10, Q_OUTSREF).

269. The method according to any preceding example, wherein said phase value (FI, FI(r), XI (r)) is a temporal relation value (FI, FI(r)).

270. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point (205, 550; X) of the centrifugal pump (10); and/or wherein said phase value (FI, FI(r), Xl(r)) is indicative of a current operating point (205, 550; X) of the centrifugal pump (10).

271. The method according to any preceding example, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point deviation (FIDEV; FIDEV(P+1 ); 550(p+ 1 )) from a Best Efficiency Point of operation of the centrifugal pump (10).

272. The method according to any preceding example, further comprising displaying, on a user interface, said at least one set point parameter (Ulsp, U2SP; U2ASP; U2BSP) as a suggestion to a user.

273. The method according to any preceding example when including example 254, wherein said at least one set point parameter (U I SP, U2SP; U2ASP; U2BSP) is based on a desired temporal relation value (FIREF, FIREFW, XI REF).

274. The method according to any preceding example when including example 254, wherein said at least one set point parameter (U I SP, 2SP; U2ASP; U2BSP) is based on a desired temporal relation value (FIREF, FIREFW, XI REF), said desired temporal relation value (FIREF, FlREF(r), XI REF) being indicative of a desired pump operating point (205REF, 550 REF; XI REF (r))-

275. The method according to any preceding example when including example 254, wherein said rotation speed set point value (U I SP, f_ROTSP) is based on a desired impeller rotational speed (U I REF, f_ROTREF, X3REF).

276. The method according to any preceding example when including example 254, wherein said rotation speed set point value (U 1 SP, fROTsp) is based on a desired impeller rotational speed (U IREF, fRoTREF, X REF), said desired impeller rotational speed (UI REF, fROTREF, X3REF) being indicative of a desired flow (Y2REF, QOUT REF, Q_OUTS REF) and/or a desired Head (YIREF, P54REF).

277. The method according to any preceding example, wherein adjusting the first valve set point value (U2SP, U2ASP) occurs during operation of the pump.

278. The method according to any preceding example, wherein adjusting the second valve set point value (U2SP, U2BSP) occurs during operation of the pump.

279. A computer program, loadable into a digital memory of an apparatus (150) having a data processor (350), the computer program comprising computer program code (380, 394, 410) adapted to perform the steps of the method according to any preceding example when said computer program is run on a data processor.

280. The computer program according to example 279, the computer program being embodied on a computer readable medium.

281. An apparatus for monitoring and/or operating a centrifugal pump (10) and/or a fluid system (52), the apparatus being configured to perform the method according to any preceding example.

282. The apparatus according to example 281, further comprising one or more hardware processors configured to perform the method according to any preceding example.

283. The method or apparatus according to any preceding example, wherein said fluid pressure pulsation event is a fluid pressure pulsation amplitude; and said temporal relation value (FI, FI(r)) is a phase value (FI, FI(r)) of the detected pressure pulsation amplitude (P54), said phase value (FI, FI(r)) being indicative of the current Operating Point (205) in relation to BEP.

284. The method or apparatus according to any preceding example, wherein the impeller position at the moment of occurrence of the fluid pressure pulsation amplitude peak value (Sp, P54, P77) is indicative of the current Operating Point (205) in relation to BEP.

285. The method or apparatus according to any preceding example, wherein a position of a tip of a vane (310) in relation to a tip of a volute tongue (65) at the moment of occurrence of the fluid pressure pulsation amplitude peak value (Sp, P54, P77) is indicative of the current Operating Point (205) in relation to BEP.

286. A method for monitoring an internal state (X; XI, X2; FI(r), Sp(r)) of a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the rotatable impeller (20) having a first number (L) of vanes for urging, when the rotatable impeller (20) rotates, a fluid material (30) from a pump inlet (66) into a volute (75), thereby causing a fluid material pulsation (PFP) having a repetition frequency (f ) dependent on a speed of rotation (AROT) of the impeller (20); the method comprising receiving, by a status parameter extractor (450), a measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)) including a time sequence of measurement sample values (Se(i), S(j), S(q)) dependent on the fluid material pulsation (PFP),' receiving, by said status parameter extractor (450), a position signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said rotatable impeller (20) in relation to said casing; generating, by said status parameter extractor (450) based on the received position signal (Ep, P(i), P(j), P(q)), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution; said certain number (L) being equal to said first number (L); detecting, by said status parameter extractor (450), a first occurrence of a first reference position signal value (1; 1C, 0%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting, by said status parameter extractor (450), a second occurrence of a second reference position signal value (1 ; 1C; 100%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting, by said status parameter extractor (450), a third occurrence of an event signature (Sp(r); Sp) in said time sequence of measurement sample values (Se(i), S(j), S(q)) when said first number (L) is higher than one so that said detected event signature (Sp(r); Sp) is indicative of a fluid material pressure pulsation (P54, +, -) generated when said first number (L) of vanes interact with said fluid material (30) in said volute (75); said detected event signature (Sp(r); Sp) being repetitive with said first number (L) of occurrences per impeller revolution; generating, by said status parameter extractor (450), data indicative of a first duration between said first occurrence and said second occurrence; and generating, by said status parameter extractor (450), data indicative of a second duration between said first occurrence and said third occurrence or data indicative of a second duration between said third occurrence and said second occurrence; generating, by said status parameter extractor (450), data indicative of a temporal relation value (FI(r), XI (r), R-r(r); TD) between said second duration, and said first duration.

287. The method according to example 286 or any preceding example, wherein said temporal relation value (FI(r), Xl(r)) is indicative of an aspect (XI, FI(r) ) of said internal state (X) of the monitored centrifugal pump (10).

288. The method according to example 286 or any preceding example, wherein said temporal relation value (FI(r), Xl(r), Rr(r); TD) is indicative of a current operating point (205, 550, 550(r) ) in relation to a best efficiency point of operation (BEP, 550BEP) of said centrifugal pump (10).

289. A method of detecting an operating point (205, 550, 55O(r)) of a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the rotatable impeller (20) having a first.number (L) of vanes for urging, when the rotatable impeller (20) rotates, a fluid material (30) from a pump inlet (66) into a volute (75), thereby causing a fluid material pulsation (PFP) having a repetition frequency (fi ) dependent on a speed of rotation (fpo?) of the impeller (20); the method comprising receiving, by a status parameter extractor (450), a measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)) including a time sequence of measurement sample values (Se(i), S(j), S(q)) dependent on the fluid material pulsation (PFP , receiving, by said status parameter extractor (450), a position signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of the rotatable impeller (20) in relation to said casing; generating, by said status parameter extractor (450) based on the received position signal (Ep, P(i), P(j), P(q)), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1 , 1 C) of a certain number (L) of stationary reference positions (Ps, Pc, P 1 , P2, P3, P4, P5, PL) per impeller revolution; said certain number (L) being equal to said first number (L); detecting, by said status parameter extractor (450), a first occurrence of a first reference position signal value (1; 1C, 0%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting, by said status parameter extractor (450), a second occurrence of a second reference position signal value (1; 1C; 100%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting, by said status parameter extractor (450), a third occurrence of an event signature (Sp(r); Sp) in said time sequence of measurement sample values (Se(i), S(j), S(q)) when said first number (L) is higher than one so that said detected event signature (Sp(r); Sp) is indicative of a fluid material pressure pulsation (P54, +, -) generated when the first number (L) of vanes interact with the fluid material (30) in the volute (75); said detected event signature (Sp(r); Sp) being repetitive with said first number (L) of occurrences per impeller revolution; generating, by said status parameter extractor (450), data indicative of a first duration between said first occurrence and said second occurrence; and generating, by said status parameter extractor (450), data indicative of a second duration between said first occurrence and said third occurrence or data indicative of a second duration between said third occurrence and said second occurrence; generating, by said status parameter extractor (450), data (XI, FI(r) ) indicative of said operating point (205, 550, 550(r)) in relation to a best efficiency point of operation (BEP, 550BEP) of said centrifugal pump (10) based on a temporal relation value (FI(r), Xl(r), R-r(r); TD) between said second duration, and said first duration.

290. The method according to example 289 or any preceding example, wherein said temporal relation value (FI(r), Xl(r)) is indicative of an aspect (XI, FI(r) ) of an internal state (X) of the monitored centrifugal pump (10).

291. A method of monitoring a centrifugal pump (10) having a casing (62) in which a rotatable impeller (20) is disposed, the rotatable impeller (20) having a first_number (L) of vanes (310) for urging, when the rotatable impeller (20) rotates, a fluid material (30) from a pump inlet (66) into a volute (75), thereby causing a fluid material pulsation (PFP) having a repetition frequency (fa) dependent on a speed of rotation (FROT) of the impeller (20); wherein said first number (L) is higher than one; the method comprising receiving, by a status parameter extractor (450), a measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)) including a time sequence of measurement sample values (Se(i), S(j), S(q)) dependent on the fluid material pulsation (PFP)', receiving, by said status parameter extractor (450), a position signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of the rotatable impeller (20) in relation to said casing; generating, by said status parameter extractor (450) based on said received measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)) and said received position signal (Ep, P(i), P(j), P(q)), at least one status parameter value (XI (r), FI(r)) indicative of an internal state (X) of the pump (10), said at least one status parameter value including a first status parameter value (Xl(r), FI(r), TD, Rr(r) ) indicative of an operating point (205, 550, 550(r)) of the centrifugal pump (10) in relation to a best efficiency point of operation (BEP, 550BEP) of the centrifugal pump (10).

292. The method according to example 291 or any preceding example, wherein said generating step includes generating, by said status parameter extractor (450) based on the received position signal (Ep, P(i), P(j), P(q)), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution; said certain number (L) being equal to said first number (L); detecting, by said status parameter extractor (450), a first occurrence of a first reference position signal value (1 ; 1C, 0%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting, by said status parameter extractor (450), a second occurrence of a second reference position signal value (1 ; 1C; 100%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting, by said status parameter extractor (450) in said time sequence of measurement sample values (Se(i), S(j), S(q)), a third occurrence of an event signature (Sp(r); Sp) which is repetitive with said first number (L) of occurrences per impeller revolution when said first number (L) is higher than one so that said detected repetitive event signature (Sp(r); Sp) is indicative of a fluid material pressure pulsation (P54, +, -) generated when the vanes (310) interact with the fluid material (30) in the volute (75); or detecting, by said status parameter extractor (450), a third occurrence of an event signature (Sp(r); Sp) in said time sequence of measurement sample values (Se(i), S(j), S(q)); said detected event signature (Sp(r); Sp) being indicative of a fluid material pressure pulsation (P54, +, -) generated when the vanes (310) interact with the fluid material (30) in the volute (75); said detected event signature (Sp(r); Sp) being repetitive with said first number (L) of occurrences per impeller revolution.

293. The method according to example 291 or 292 or any preceding example, wherein said generating step includes generating, by said status parameter extractor (450), data indicative of a first duration between said first occurrence and said second occurrence; and generating, by said status parameter extractor (450), data indicative of a second duration between said first occurrence and said third occurrence or data indicative of a second duration between said third occurrence and said second occurrence; generating, by said status parameter extractor (450), said at least one status parameter value (Xl(r), FI(r)) based on a temporal relation value (FI(r), Xl (r), R?(r); TD) between said second duration, and said first duration. 294. The method according to example 293 or any preceding example, further comprising generating, by said status parameter extractor (450), at least one status parameter value (Xl(r), FI(r), Xl(t), FI(t)) indicative of an internal state (X, X(r), X(t)) of the pump (10), at a point in time (r; t), said at least one status parameter value including a first status parameter value (X 1 (r), FI(r), Xl(t), FI(t)) indicative of an operating point (205, 550, 550(r); 550(f)) of the centrifugal pump (10) at a point in time (r; t) in relation to a best efficiency point of operation (BEP(r), 550BEp(r); BEP(t), 550BEp(t) ) of the centrifugal pump (10) at said point in time (r; t).

295. The method according to any preceding example or any of examples 255 - 259, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a lower pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is lower than a desired system delivery flow (Y I OREF, Q_OUTSREF); then said first valve set point value (U2SP, U2ASP) is adjusted, by said control module (150B, 755), so as to decrease, or eliminate, said another flow (QR) e.g. by decreasing said second adjustable cross sectional area (AVLR ) and/or by increasing said first adjustable cross sectional area (AVLS ); and/or said rotation speed set point value (UISP, f_ROTSP) is adjusted, by said control module (150B, 755), so as to increase said impeller rotational speed (Ul, fpor), e.g. until said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP).

296. A method for monitoring and/or operating a centrifugal pump (10; 10 A; 10B; 10C; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20) is disposed for urging a fluid material (30) via the volute to a pump outlet (66) which is coupled to a fluid system (52) via a valve arrangement (VL; VH ), the method comprising: receiving a measuring signal indicative of a fluid pressure pulsation (PFP) in the fluid material (30); receiving a reference signal indicative of a rotational reference position of said rotating impeller; generating data indicative of an internal state of the centrifugal pump, said data including a phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)) based on said measuring signal and said reference signal; wherein said phase value (FI, FI(r), Xl(r)) is indicative of a current operating point of the pump in relation to a Best Efficiency Point of operation, and/or wherein said temporal relation value (Fl, FI(r), XI (r)) is indicative of a current operating point of the pump in relation to a Best Efficiency Point of operation, generating at least one set point parameter (UI SP, U2SP) based on said phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), XI (r)); wherein said at least one set point parameter (UI SP, U2SP) comprises a rotation speed set point value (UISP, f_ROT SP) for controlling a rotational speed (Ul, fpor) of the impeller (20).

297. A system comprising: a centrifugal pump (10; 10A; 10B; 10C; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20) is disposed; the impeller (20) having a first number (L) of vanes (310) for urging a fluid (30) via the volute (75) to a pump outlet (66) for delivering a pump outlet flow (QOUT, ¥2), thereby causing a fluid material pulsation (PFP),' a valve arrangement (VL; VH ) for receiving said pump outlet flow (QOUT, Y2); a fluid system (52) for receiving at least a portion (Y 10, Q_OUTS) of said pump outlet flow (QOUT, Y2) from said valve arrangement (VL; VH ), or a fluid system (52) for receiving a system input flow (Y10, QOUT) of fluid material (30) from said valve arrangement (VL; VH ); a measurement sensor (70, 70s4, 70?7, 70₇₈, 330, 350, 450) for generating a measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)) including a time sequence of measurement sample values (Se(i), S(j), S(q)) dependent on the fluid material pulsation (PFP),' a position sensor (170, 180) for generating a position signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of the rotatable impeller (20) in relation to said casing; a status parameter extractor (450) adapted to detect, in said measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)), occurrences of a signal event signature (Sp(r); Sp) having an event repetition frequency (fp) that depends on said first number (L) when said first number (L) is higher than unity, i.e. higher than one; said status parameter extractor (450) being adapted to generate, based on said position signal (Ep, P(i), P(j), P(q)), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution such that said reference position signal values (Ps, Pc, 1, 1C) have a certain occurrence frequency (FR), said certain occurrence frequency (FR) being equal to said event repetition frequency (FR ; said status parameter extractor (450) being configured to obtain at least one status parameter value (X 1 (r), FI(r)) from a temporal relation between said repetitive signal event signature (Sp(r); Sp) occurrences and said repetitive reference position signal value (Ps, Pc, 1, 1C) occurrences; said at least one status parameter value (Xl (r), FI(r)) indicative of an internal state (X) of the pump (10), said at least one status parameter value including a first status parameter value (Xl(r), FI(r), TD, Rr(r) ) indicative of an operating point (205, 550, 550(r)) of the centrifugal pump (10) in relation to a best efficiency point of operation (BEP, 550BEP) of the centrifugal pump (10); a controller (240; 755; 150B) for generating at least one set point parameter (Ulsp, U2SP) based on said first status parameter value (Xl(r), FI(r), TD, Rr(r) ); wherein said at least one set point parameter (Ulsp, U2SP) comprises a rotation speed set point value (Ulsp, fROTSp) for controlling a rotational speed (Ul, FROT) of the impeller (20).

298. The system according to example 297 or any preceding example, wherein said sensor (70, 70s4, 70?7, 70₇₈) is mountable or attachable so as to generate a measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)) having an amplitude that depends on said fluid material pulsation (PFP) in said pump outlet flow (QOUT, Y2) or in said volute (75).

299. (blank)

300. (blank)

301. A system comprising: an apparatus (150A, 450) for monitoring an internal state (X) of a centrifugal pump (10; 10A; 10B; 10C; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20) is disposed for urging a fluid (30) via the volute to a pump outlet (66, 54); a valve arrangement (VL; VH ) having a valve inlet which is connectable to a pump outlet (66, 54), and a first valve outlet for delivery of a system delivery flow (Y10, Q_OUTS) of fluid to a fluid system (52, 40, 50, 56); a sensor (70) for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of a fluid pressure pulsation (PFP) in the fluid (30); a device (170, 180) for generating a reference signal indicative of a rotational reference position of a rotating impeller (20); wherein said apparatus (150A, 450) is configured to generate, based on said measuring signal and said reference signal, data (XI; X2; X3; X4) indicative of said internal state (X); said internal state data (XI; X2; X3; X4) including a phase value (FI, FI(r), Xl(r)), wherein said phase value (FI, FI(r), Xl(r)) is indicative of a current operating point (205, 550, 550(r)) of the pump in relation to a Best Efficiency Point of operation; a control module (150B, 755) configured to generate at least one set point parameter (UI SP, U2SP) based on said phase value (FI, FI(r), XI (r)); wherein said at least one set point parameter (UI SP, U2SP) comprises a rotation speed set point value (UISP, FROTSP) for controlling a rotational speed (Ul, FROT) of the impeller (20).

302. The system according to example 301, wherein said control module (150B, 755) is configured to generate said rotation speed set point value (UISP, fuorsp) based on a desired system delivery flow (Q_OUTSREF, YI OREF, FROTREF) and on said phase value (FI, FI(r), Xl(r)); and wherein said rotation speed set point value (UISP, FROTSP) affects pump outlet fluid pressure (Yl, P54) and/or pump outlet fluid flow (Y2, QOUT) at said pump outlet (66, 54).

303. The system according to example 301 or 302, wherein said control module (150B, 755) is configured to adjust said rotation speed set point value (UISP, FROTSP) SO as to increase said impeller rotational speed (Ul, FROT) when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow.

304. The system according to example 301, or 303, wherein said control module (150B, 755) is configured to adjust said rotation speed set point value (UISP, fROTSp) to increase said impeller rotational speed (Ul, FROT) until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YI OREF, Q_OUTSREF) when said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow.

305. The system according to any of examples 301-304, wherein said valve arrangement (VL; VH) comprises a flow control valve (VL; VH) having a first adjustable cross sectional area (AVLS; AVHS) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said at least one set point parameter (U 1 SP, U2SP) comprises a first valve set point value (U2SP, U2ASP) for controlling said first adjustable cross sectional area (AVLS; AVHS).

306. The system according to any of examples 301-305, wherein said valve arrangement (VL; VH) comprises a first adjustable cross sectional area (AVLS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said valve arrangement (VL; VH) comprises a second adjustable cross sectional area (AVLR ) for controlling another flow (QR), such as for example a return flow (QR); said another flow (QR) being diverted from flowing to the fluid system (52), wherein said at least one set point parameter (UI SP, U2SP) comprises a first valve set point value (U2SP, U2ASP) for simultaneously controlling said first adjustable cross sectional area (AVLS ) and said second adjustable cross sectional area (AVLR )•

307. The system according to any of examples 305 or 306, wherein said control module (150B, 755) is configured to initially set said first valve set point value (U2SP, U2ASP) so that said system delivery flow (Y10, Q_OUTS) is equal to said pump outlet fluid flow (Y2, QOUT).

According to an embodiment this may be achieved, for example, by simultaneously controlling said first adjustable cross sectional area (AVLS ) and said second adjustable cross sectional area (AVLR ) so as to direct all, or substantially all, of said pump outlet fluid flow (Y2, QOUT) to said fluid system (52).

308. The system according to any of examples 305 to 307, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a lower pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), and said system delivery flow (Y 10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said rotation speed set point value (UISP, FROTSP) SO as to increase said impeller rotational speed (Ul, FROT), e.g. until said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said control module (150B, 755) is configured to adjust said first valve set point value (U2SP, U2ASP) so as to increase said another flow (QR) by increasing said second adjustable cross sectional area (AVLR ) and by decreasing said first adjustable cross sectional area (AVLS )•

309. The system according to any of examples 305 to 308, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with pump outlet flow (Y2, QOUT) at, or substantially at, Best Efficiency Point of pump outlet flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said first valve set point value (U2SP, U2ASP) so as to minimize, or eliminate, said another flow (QR) by decreasing said second adjustable cross sectional area (AVLR ) and by increasing said first adjustable cross sectional area (AVLS ).

This is advantageously done in order to minimize return flow (QR). However, when the first valve set point value (U2SP, U2ASP) is adjusted so as to minimize, or eliminate, said another flow (QR), then this may lead to a higher system delivery flow (Y10, Q_OUTS). 310. The system according to any preceding example or according to any of examples 305 to

309, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a flow at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is higher than to a desired system delivery flow (Y I OREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said rotation speed set point value (UISP, FROTSP) SO as to decrease said impeller rotational speed (Ul, f_ROT), e.g. until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF).

311. The system according to any preceding example or according to any of examples 305 to

310, wherein said valve arrangement (VL; VH) comprises a flow control valve (VH) having a third adjustable cross sectional area (AVHS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said at least one set point parameter (U 1 SP, U2SP) comprises a second valve set point value (U2SP, U2BSP) for controlling said third adjustable cross sectional area (AVHS ).

312. The system according to any preceding example or according to any of examples 305 to

311, wherein when said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) with a higher pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), then said control module (150B, 755) is configured to adjust said second valve set point value (U2SP, U2BSP) so as to reduce said third adjustable cross sectional area (AVHS ). It is noted that a reduction of the third adjustable cross sectional area (AVHS ) will cause a reduced pump outlet fluid flow (Y2, QOUT) and an increased pump outlet fluid pressure (Yl, P54). In this manner, for example, a pump that was running at back pressure Yl below BEP back pressure (YI BEP) is operated to increase pump outlet fluid pressure (Yl, P54), thereby allowing the pump to run at a more energy efficient point of operation 205 at or near BEP pressure (YI BEP), and a surplus pressure, i.e. a difference between pump outlet fluid pressure (Yl, P54) at BEP (YIBEP) and the system delivery Head (P54S), is exhibited as a pressure difference across the flow control valve (VH).

However, it is noted that the resulting reduced pump outlet fluid flow (Y2, QOUT) may render a system delivery flow (Y10, Q_OUTS) to the fluid system (52) that is lower than a desired system delivery flow (YI OREF, Q_OUTSREF).

313. The system according to any preceding example or according to any of examples 305 to

312, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a flow at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is lower than to a desired system delivery flow (YIOREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said rotation speed set point value (UISP, FROTSP) to increase said impeller rotational speed (Ul, FROT), e.g. until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YI OREF, Q_OUTSREF).

314. The system according to any preceding example or according to any of examples 305 to

313, wherein said phase value (FI, FI(r), XI (r)) is a temporal relation value (FI, FI(r)).

315. The system according to any preceding example or according to any of examples 301 to

314, wherein said phase value (FI, FI(r), X 1 (r)) is indicative of a current operating point deviation (FIDEV; FIDEV(P+1); 550(p+ 1 )) from a Best Efficiency Point of operation of the centrifugal pump (10).

316. The system according to any preceding example or according to any of examples 301 to

315, wherein said apparatus (150A, 450) is configured to display, on a user interface (210, 210S, 250), said at least one set point parameter (UISP, U2SP; U2ASP; U2BSP) as a suggestion to a user (230). 317. The system according to any preceding example or according to any of examples 301 to

316, wherein said control module (150B, 755) is configured to generate said at least one set point parameter (U 1 SP, U2SP; U2ASP; U2BSP) based on a desired phase value (FIREF, FlREF(r), X 1 REF), said desired phase value (FIREF, FIREFCF), XI REF) being indicative of a desired pump operating point (205REF, 550 REF; XI REF (r)).

318. The system according to any preceding example or according to any of examples 301 to

317, wherein said control module (150B, 755) is configured to generate said rotation speed set point value (U I SP, f_ROTSP) based on a desired impeller rotational speed (U IREF, f_ROTREF, X3REF).

319. The system according to any preceding example or according to any of examples 301 to

318, wherein said control module (150B, 755) is configured to generate said rotation speed set point value (UI SP, f_ROTSP) based on a desired impeller rotational speed (U I REF, f_ROTREF, X3REF), said desired impeller rotational speed (U I REF, f_ROTREF, X3REF) being indicative of a desired flow (Y2REF, QOUT REF, Q_OUTS_REF) and/or a desired Head (Y IREF, P54REF).

320. The system according to any preceding example or according to any of examples 301 to

319, wherein said control module (150B, 755) is configured to adjust the first valve set point value (U2SP, U2ASP) during operation of the pump.

321. The system according to any preceding example or according to any of examples 301 to

320, wherein said control module (150B, 755) is configured to adjust the second valve set point value (U2SP, U2BSP) during operation of the pump.

322. The system according to any preceding example or according to any of examples 301 to

321, wherein the another flow (QOUTR) is a return flow for returning fluid to a fluid storage or to an inlet side of the pump (10). 323. The system according to any preceding example or according to any of examples 301 to 322, wherein said fluid system (52, 40, 50, 56) includes a pipe for transporting fluid from the first valve outlet to a fluid consumer (50).

324. The system according to any of examples 1 to 23, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a lower pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is lower than a desired system delivery flow (YI OREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said first valve set point value (U2SP, U2ASP) so as to decrease, or eliminate, said another flow (QR); and/or said control module (150B, 755) is configured to adjust said rotation speed set point value (UISP, f_ROTSP) so as to increase said impeller rotational speed (Ul, FROT), e.g. until said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP).

325. A system comprising: an apparatus (150A, 450) for monitoring an internal state (X) of a centrifugal pump (10; 10A; 10B; 10C; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20) is disposed for urging a fluid (30) via the volute to a pump outlet (66, 54); a valve arrangement (VL; VH ) having a valve inlet which is connectable to a pump outlet (66, 54), and a first valve outlet for delivery of a system delivery flow (Y 10, Q_OUTS) of fluid to a fluid system (52, 40, 50, 56); a sensor (70) for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of a fluid pressure pulsation (PFP) in the fluid (30); a device (170, 180) for generating a reference signal indicative of a rotational reference position of a rotating impeller (20); wherein said apparatus (150A, 450) is configured to generate, based on said measuring signal and said reference signal, data (XI; X2; X3; X4) indicative of said internal state (X); said internal state data (XI; X2; X3; X4) including a phase value (FI, FI(r), Xl(r)), wherein said phase value (FI, FI(r), Xl(r)) is indicative of a current operating point (205, 550, 550(r)) of the pump in relation to a Best Efficiency Point of operation; a control module (150B, 755) configured to generate at least one set point parameter (UI SP, U2SP) based on said phase value (FI, FI(r), Xl(r)); wherein said at least one set point parameter (UI SP, U2SP) comprises a rotation speed set point value (UISP, f_ROTSP) for controlling a rotational speed (Ul, FROT) of the impeller (20).

326. A method for monitoring and/or operating a centrifugal pump (10; 10A; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20), having a first number of vanes (310), is disposed for urging a fluid (30) via the volute to a pump outlet (66, 54) for delivery to a fluid system (52, 40, 50, 56); the method comprising the steps: generate, by a first sensor (70), a first measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of a first fluid pressure pulsation (PFP) originating in the volute (75; 75A); generate, with a position signal generator (170, 180), a reference signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said impeller (20); generate, by one or more hardware processors, at least one pump status parameter value (Xl(r), FI(r); X2(r); X3(r); X4(r) ) indicative of an internal state (X) of the pumping process based on said measuring signal and said reference signal; said at least one pump status parameter value (Xl(r), FI(r); X2(r); X3(r); X4(r) ) comprising a first pump parameter value (XI, FI) indicative a current operating point (205, 550, 550(r)) of the centrifugal pump (10; 10A; 10D) in relation to a Best Efficiency Point of operation; deliver, by one or more hardware processors (350), at least one set point parameter (UISP, U2SP); wherein said at least one set point parameter (UI SP, U2SP) comprises a rotation speed set point value (UISP, f_ROTSP) for controlling a rotational speed (Ul, f_ROT) of the impeller (20), said at least one set point parameter (UISP, U2SP) thereby influencing said internal state (X) of the pumping process; wherein said internal pumping process state (X) affects an internal state (Y) of the fluid system (52, 40, 50, 56); analyse, e.g. by one or more sensors (70Y) and/or by one or more hardware processors (350), said fluid system (52, 40, 50, 56) so as to generate at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) based on said analysis; said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) being indicative of an internal state (Y) of the fluid system (52, 40, 50, 56); said fluid system internal state (Y) relating to pressure and/or flow of fluid (30) in said fluid system (52, 40, 50, 56); the method further comprising receiving system reference data (Y I REF, Y2REF, Y3REF, ... YUREF ) indicative of a desired fluid system internal state (YREF); and generating said rotation speed set point value (UISP, f_ROTSP) based on said system reference data (Y I REF, Y2 EF, Y3REF, ... YHREF ); and said at least one pump status parameter value (Xl, FI; X2; X3; X4).

327. The method according to example 326, wherein said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) comprises a fluid system parameter value (Y3; Y6) indicative of a first fluid system pulsation amplitude (Y3, Spy) having a first fluid system pulsation repetition frequency (Y4; Y7).

328. The method according to example 326 or 327, further comprising generating, based on said first measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)), a time sequence of first measuring signal sample values (Se(i), S(j), S(q)); and/or generating, based on said reference signal (Ep, P(i), P(j), P(q)), a time sequence of reference signal sample values (P(i), P(j), P(q)).

329. The method according to example 326, 327 or 328, wherein said generating of at least one pump status parameter value (Xl(r), FI(r); X2(r);

X3(r); X4(r) ) comprises generating, said first pump parameter value (XI, FI) based on a time sequence of first measuring signal sample values (Se(i), S(j), S(q)) and a time sequence of reference signal sample values (P(i), P(j), P(q)); wherein said generating of said first pump parameter value (XI, FI) includes detecting, in said time sequence of first measuring signal sample values (Se(i), S(j), S(q)), by one or more hardware processors (350) when said first number (L) is higher than one, an event signature (Sp(r); Sp) which is repetitive with an event signature repetition frequency (fit) of said first number (L) of occurrences per impeller revolution such that said detected repetitive event signature (Sp(r); Sp) is indicative of a fluid material pressure pulsation (PFP, P54, +, -) generated when the vanes (310) interact with the fluid material (30) in the volute (75); and wherein said time sequence of position signal sample values (P(i), P(j), P(q)) includes a reference sample value (Ps, Pc, 1, 1C) which is indicative of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution; said certain number (L) being equal to said first number (L).

330. The method according to example 329, wherein said detection of an event signature (Sp(r); Sp) includes identifying a relevant time sequence of first measuring signal sample values (Se(i), S(j), S(q)) based on said time sequence of reference signal sample values (P(i), P(j), P(q)) so that said relevant time sequence comprises first measuring signal sample values (Se(i), S(j), S(q)) relating to a duration between at least two of said reference sample values (Ps, Pc, 1, 1C).

331. The method according to any preceding example or according to any of examples 326 - 330; wherein said first pump parameter value (XI, FI) is based on a phase difference between said repetitive event signature (Sp(r); Sp) and said repetitive reference sample value (Ps, Pc, 1, 1C). 332. The method according to any preceding example or according to any of examples 326 - 331; wherein said first pump parameter value (XI, FI) is based on a temporal relation (RT) between occurrence of said repetitive event signature (Sp(r); Sp) and occurrence of said repetitive reference sample value (Ps, Pc, 1, 1C).

333. The method according to any preceding example or according to any of examples 326 to 332; wherein said analysis includes: generating, by a second sensor (70Y), a second measuring signal (SEAY3, SMDYS) indicative of a fluid pressure pulsation (PFP) originating in the fluid system (52, 40, 50, 56); and generating, by one or more hardware processors, a first fluid system pulsation amplitude (Y3, SPY) based on said second measuring signal (SEAY3, SMDY3).

334. The method according to any preceding example or according to any of examples 327 to 333; wherein said first fluid system pulsation repetition frequency (Y4; Y7) is equal to said event signature repetition frequency (£R).

335. The method according to any preceding example or according to any of examples 326 to 334; wherein further comprising generate at least one pump status parameter reference value (XlREp(r); X2REF(r)) based on said system reference data (Y I REF, Y2REF, Y3REF, ... YHREF); said at least one pump status parameter reference value (X I REFO-); X2REF(r)) being indicative of a desired internal state (XREF) of the pumping process for causing said desired fluid system internal state (YREF(r), Y I REF, Y2REF, Y3REF, ... YUREF); and generate said rotation speed set point value (U 1 SP, f_ROTSP) based on said at least one pump status parameter reference value (XI REFO-), FIREF (r)); and said at least one pump status parameter value (Xl(r), FI(r); X2(r);

X3(r); X4(r) ). 336. The method according to any preceding example or according to any of examples 326 to 335; wherein further comprising said internal state (X) of the pumping process is indicated by a number of internal pump state parameters (XI, X2, X3,..., Xm); wherein an internal state parameter (XI, X2, X3,..., Xm) describes an aspect of the pumping process.

337. The method according to any preceding example or according to any of the examples 326 to 336; wherein further comprising generating an internal pump state vector (X); said internal pump state vector (X) comprising an integer number m of internal pump state parameters (XI , X2, X3,..., Xm) ; wherein an internal state parameter (XI, X2, X3,..., Xm) describes an aspect of the pumping process.

338. The method according to any preceding example or according to any of the examples 326 to 337; wherein further comprising said fluid system internal state (Y(r), Yl, Y2, Y3, ... Yn) is indicated by a number of fluid system internal state parameters (Yl, Y2, Y3, ... Yn); wherein an individual fluid system internal state parameter (Yl, Y2, Y3, ... Yn) describes an aspect of said pressure and/or flow of fluid (30) in said fluid system (52, 40, 50, 56).

339. The method according to any preceding example or according to any of the examples 326 to 338; wherein further comprising generating a fluid system internal state vector (Y); said fluid system internal state vector (Y) comprising an integer number n of fluid system internal state parameters (Yl , Y2, Y3, ... Yn); wherein an individual fluid system internal state parameter (Yl, Y2, Y3, ... Yn) describes an aspect of said pressure and/or flow of fluid (30) in said fluid system (52, 40, 50, 56).

340. The method according to any preceding example or according to any of the examples 326 to 339; wherein further comprising generating a set point vector (USP); said set point vector (USP) comprising a number of set point parameter values (UI SP, U2SP, U3SP,... Uk); wherein an individual set point parameter value (U I SP, U2SP, U3SP,... Uk) describes a set point value for controlling an aspect of operation of the pump (10) and/or for controlling an aspect of operation of a valve arrangement (1220); said rotation speed set point value (U1 SP, f_ROTSP) being one of said set point parameter values (UI SP, U2SP, U3SP,... Uk).

341 . The method according to any preceding example or according to any of the examples 326 to 340; wherein further comprising said rotation speed set point value (UI SP, fpoTSp) is generated based on pump reference data ((X I REF, X2REF, X3REF, ... XIUREF ) indicative of a desired internal state (XREF) of the pumping process; wherein said pump reference data ((X I REF, X2REF, X3REF, XHIREF ) is based on said system reference data (YI REF, Y2REF, Y3REF, ... YHREF ), and correlation data (1 170, 1 180) indicative of a causal relationship between said system reference data (Y I REF, Y2REF, Y3REF, ... YHREF ) and a corresponding internal state (XREF) of the pumping process.

342. The method according to any preceding example or according to any of the examples 326 to 341 ; wherein further comprising generating said set point vector (USP) based on a desired internal state (XREF) of the pumping process; wherein said desired internal state (XREF) of the pumping process is based on said desired fluid system internal state (YREFW, Y I REF, Y2REF,

Y3REF, ... YHREF), and correlation data (1 170, 1 180) indicative of a causal relationship between said desired fluid system internal state (YREF) and a desired corresponding internal state (X) of the pumping process.

343. The method according to any preceding example or according to any of the examples 326 to 342; wherein further comprising said data indicative of a desired fluid system internal state (YREp(r), Y I REF, Y2REF, Y3REF, ... YHREF) includes a value indicative of a desired fluid system flow (Y I OREF, Q_OUTSREF) and/or indicative of a desired fluid system pressure Y9REF, PS4S_REF). 344. The method according to any preceding example or according to any of the examples 326 to 343; wherein further comprising said data indicative of a desired fluid system internal state (YREF(T), YIREF, Y2REF, Y3REF, ... YUREF) includes a value (Y3REF) indicative of a desired maximum fluid system pulsation amplitude (Y3REF, Y6REF, SPYREF).

345. The method according to any preceding example or according to any of the examples 326 to 344; wherein further comprising said data indicative of a desired fluid system internal state (YREF(r), YI EF, Y2REF, Y3REF, ... YHREF) includes a desired fluid system internal state vector (YREFC*)); said desired fluid system internal state vector (YREFO ) including data (Y1 OREF) indicative of a desired fluid system flow (Y 1 OREF, Q_OUTSREF) and/or a desired fluid system pressure (Y9REF, PS4SREF), and/or data (Y3REF) indicative of a desired maximum fluid system pulsation amplitude (Y3REF, Y6REF, SPYREF).

346. The method according to any preceding example or according to any of the examples 326 to 344; wherein further comprising said first measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) is indicative of said first fluid pressure pulsation (PFP) having a first repetition frequency (f ); said first repetition frequency (IR) being a number of occurrences of a repeating event (Sp) per revolution of said impeller (20); wherein said first repetition frequency (fk) depends on a speed of impeller rotation (fkoT), and wherein said reference signal is indicative of a reference position repetition frequency (fR,); said reference position repetition frequency (fR, X4) being equal to said first repetition frequency (fR).

347. The method according to any preceding example or according to any of the examples 326 to 344; wherein further comprising detecting a first occurrence of a first reference position signal value (1 ; 1C, 0%) in a time sequence of position signal sample values (P(i), P(j), P(q)); detecting a second occurrence of a second reference position signal value (1 ; 1C; 100%) in said time sequence of position signal sample values (P(i), P(j), P(q)); detecting a third occurrence of an event signature (Sp(r); Sp) in a time sequence of measurement sample values (Se(i), S(j), S(q)); generating (1010), based on said time sequence of position signal sample values (P(i); P(j); P(q)), data indicative of a reference duration (TREFI) between said first occurrence (1 ; 1C, 0%, 0°, Pc) and said second occurrence (1; 1C, Pc, 100%, 360°); and generating (1020), based on time information (i, dt; j, t) relating to said third occurrence and time information (i, dt; j, t) relating to said time sequence of position signal sample values, a first temporal duration (TREFZ); said first temporal duration being indicative of time between said first occurrence (1 ; 1C, 0%, 0°, Pc) and said third occurrence (Sp(r); Sp), or said first temporal duration being indicative of time between said third occurrence (Sp(r); Sp) and said second occurrence (1 ; 1C, Pc, 100%, 360°); and generating (1050) data indicative of a first temporal relation (Rr(r); TD; FI(r), d>(r)) between said first temporal duration (TREF2) and said reference duration (TREFI).

348. A method for monitoring and/or operating a centrifugal pump (10; 10A; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20), having a first number of vanes (310), is disposed for urging a fluid (30) via the volute to a pump outlet (66, 54) for delivery of a fluid system flow (Y10, Q_OUTS) and/or a fluid system pressure (Y9, Ps4s) to a fluid system (52, 40, 50, 56); the method comprising the steps: generate, by a first sensor (70), a first measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of a first fluid pressure pulsation (PFP) originating in the volute (75; 75A); generate, with a position signal generator (170, 180), a reference signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said impeller (20); generate, by one or more hardware processors, at least one pump status parameter value (Xl(r), FI(r); X2(r); X3(r); X4(r) ) indicative of an internal state (X) of the pumping process based on said measuring signal and said reference signal; said at least one pump status parameter value (Xl(r), FI(r); X2(r); X3(r); X4(r) ) comprising a first pump parameter value (XI, FI) indicative a current operating point (205, 550, 550(r)) of the centrifugal pump (10; 10A; 10D) in relation to a Best Efficiency Point of operation; deliver, by one or more hardware processors (350), at least one set point parameter (UISP, U2_Sp); wherein said at least one set point parameter (U I SP, U2SP) comprises a rotation speed set point value (UISP, f_ROT SP) for controlling a rotational speed (Ul, fRcrr) of the impeller (20), said at least one set point parameter (U I SP, U2SP) thereby influencing said internal state (X) of the pumping process; wherein said internal pumping process state (X) affects an internal state (Y) of the fluid system (52, 40, 50, 56); analyse, e.g. by one or more hardware processors (350), said fluid system (52, 40, 50, 56) so as to generate at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) based on said analysis; said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) being indicative of said internal state (Y) of the fluid system (52, 40, 50, 56); said fluid system internal state (Y) relating to pressure and/or flow of fluid (30) in said fluid system (52, 40, 50, 56); the method further comprising receiving system reference data (YI REF, Y2 EF, Y3REF, ... YUREF ) indicative of a desired fluid system internal state (YREF); and generating pump reference data ((XI REF, X2REF, X3REF, ... XIHREF ) based on said system reference data (Y I REF, Y2REF, Y3 EF, ... YHREF ), and correlation data (1 170, 1 180) indicative of a causal relationship between said system reference data (Y I REF, Y2REF, Y3REF, ... YHREF ) and a corresponding internal state (XREF) of the pumping process. 349. The method according to any preceding example or according to any of the examples 326 to 348; further comprising generating said rotation speed set point value (UISP, IRO I SP) based on said generated pump reference data ((XIREF, X2REF, X3REF, ... XUIREF ); and said at least one pump status parameter value (XI, FI; X2; X3; X4).

350. The method according to any preceding example or according to any of the examples 326 to 349; further comprising controlling, by a regulator (150B; 755, 1 190), said rotation speed set point value (UISP, f oTSp) based on said generated pump reference data ((X I REF, X2REF, X3REF, ... XUIREF ); and said at least one pump status parameter value (Xl, FI; X2; X3; X4), and at least one pump status parameter error value (XI ERR, FIERR; X2ERR; X3ERR;

X4ERR); wherein said at least one pump status parameter error value (XI ERR, FIERR; X2ERR;

X3_ERR; X4ERR) depends on said generated pump reference data ((X I REF, X2REF, X3REF, ... XHIREF ), and said at least one pump status parameter value (XI , FI; X2; X3; X4).

351. The method according to any preceding example or according to any of the examples 326 to 350; wherein further comprising said at least one pump status parameter value (Xl(r), FI(r); X2(r); X3(r); X4(r) ) comprises a second pump parameter value (X2, Sp) indicative of an amplitude of the first fluid pressure pulsation (PFP); and/or said at least one pump status parameter value (Xl (r), FI(r); X2(r); X3(r); X4(r) ) comprises a third pump parameter value (X3) indicative of said rotational speed (Ul, fRor) of the impeller (20); and/or said at least one pump status parameter value (Xl(r), FI(r); X2(r); X3(r); X4(r) ) comprises a fourth pump parameter value (X4) indicative of a repetition frequency (f ) of an event signature (Sp).

352. The method according to any preceding example or according to any of the examples 326 to 351 ; wherein further comprising controlling, by a regulator (150B), a volute set point value (U2SP) in dependence on an operating point reference value (FIREFIT) ), and wherein said volute is an adaptive volute (75A) having an adjustable cross-sectional area and/or an adjustable volume, and wherein said volute set point value (U2SP; VPSP) controls said adjustable cross-sectional area and/or said adjustable volute volume.

353. The method according to any preceding example or according to any of the examples 326 to 352; wherein further comprising determining an operation parameter of the pump based on said first pump parameter value (XI, FI).

354. The method according to any preceding example or according to any of the examples 326 to 353; wherein further comprising the operation parameter comprises a rotation speed set point value (UI SP, f_ROTSP) for controlling said rotational speed (Ul, f_ROT) of the impeller (20).

355. The method according to any preceding example or according to any of the examples 326 to 354; wherein further comprising said volute is an adaptive volute (75) having an adjustable cross sectional area, and the operation parameter comprises a volute set point value (U2SP; VPSP) for controlling said adjustable cross sectional area.

356. The method according to any preceding example or according to any of the examples 326 to 355; wherein said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) comprises a first fluid system parameter value (Y3) indicative of a first fluid system pulsation amplitude.

357. The method according to example 356 or according to any of the examples 326 to 355; wherein said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) comprises a second fluid system parameter value (Y4) indicative of a repetition frequency of said first fluid system pulsation amplitude (Y3).

358. The method according to any preceding example or according to any of the examples 326 to 357; wherein said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) comprises a third fluid system parameter value (Y9) indicative of a fluid system pressure (Y9, Ps4s), such as a static pressure, in the fluid system (52, 40, 50, 56).

359. The method according to any preceding example or according to any of the examples 326 to 358; wherein said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) comprises a fourth fluid system parameter value (Y10) indicative of a fluid system flow (Q_OUTS, Y10).

360. The method according to example 326 or according to any of the examples 326 to 359 or any preceding example; wherein the generating of said rotation speed set point value (Ulsp, fRorsp) includes generating (150C2) pump reference data ((XI REF, X2REF, X3REF, ... XIBREF ) based on said system reference data (YIREF, Y2REF, Y3REF, ... YUREF ), and correlation data (1170, 1 180, C’¹) indicative of a causal relationship between said system reference data (YI REF, Y2REF, Y3 EF, ... YHREF ) and a corresponding internal state (XREF) of the pumping process, and generating (150B, 755) said at least one set point parameter (UISP, U2SP) based on said generated pump reference data ((XI REF, X2REF,

X3REF, ... XmREF ), and said at least one pump status parameter value (XI , FI; X2; X3; X4), and at least one pump status parameter error value (XI ERR, FIERR; X2ERR;

X3ERR; X4ERR), wherein said at least one pump status parameter error value (XI ERR, FIERR; X2ERR; X3ERR; X4ERR) depends on said generated pump reference data ((XI REF, X2REF,

X3REF, ... XmREF ), and said at least one pump status parameter value (XI, FI; X2; X3; X4).

361 . The method according to example 360 or according to any of the examples 326 to 359 or any preceding example; wherein said generated pump reference data (XI REF, X2REF, X3REF, ... XmREF ) includes a first pump parameter reference value (XI REF, FIREF); and wherein said at least one pump status parameter error value (XI ERR, FIERR; X2ERR; X3ERR; X4ERR) includes a first pump parameter error value (XI ERR, FIERR) indicative of a deviation between said first pump parameter reference value (XI REF, FIREF) and said first pump parameter value (XI, FI); and wherein said rotation speed set point value (UISP, FROTSP) is generated, by a controller (755, 755C), based on said first pump parameter error value (XIERR, FIERR).

362. A method for monitoring and/or operating a fluid system (52, 40, 50, 56) coupled to a centrifugal pump (10; 10A; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20), having a first number of vanes (310), is disposed for urging a fluid (30) via the volute to a pump outlet (66, 54) for delivery to the fluid system (52, 40, 50, 56); the method comprising the steps: generate, by a first sensor (70), a first measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of a first fluid pressure pulsation (PFP) originating in the volute (75; 75 A); generate, with a position signal generator (170, 180), a reference signal (Ep, P(i), P(j), P(q)) indicative of a rotational position of said impeller (20); generate, by one or more hardware processors (350), at least one pump status parameter value (Xl(r), FI(r); X2(r); X3(r); X4(r) ) indicative of an internal state (X) of the pumping process based on said measuring signal and said reference signal; said at least one pump status parameter value (Xl (r), FI(r); X2(r); X3(r); X4(r) ) comprising a first pump parameter value (XI, FI) indicative a current operating point (205, 550, 550(r)) of the centrifugal pump (10; 10A; 10D) in relation to a Best Efficiency Point of operation; deliver, by one or more hardware processors (350), at least one set point parameter (Ulsp, U2SP); wherein said at least one set point parameter (U I SP, U2SP) comprises a rotation speed set point value (U I SP, f_ROTSP) for controlling a rotational speed (Ul , fRor) of the impeller (20), said at least one set point parameter (U 1 SP, U2SP) thereby influencing said internal state (X) of the pumping process; wherein said internal pumping process state (X) affects an internal state (Y) of the fluid system (52, 40, 50, 56); said fluid system internal state (Y) relating to pressure and/or flow of fluid (30) in said fluid system (52, 40, 50, 56); analyse said fluid system (52, 40, 50, 56) so as to generate at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) based on said analysis; said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) being indicative of said internal state (Y) of the fluid system (52, 40, 50, 56); the method further comprising receiving system reference data (Y I REF, Y2 EF, Y3REF, ... YHREF ) indicative of a desired fluid system internal state (YREF); and generating a first pump parameter reference value (XI REF, FIREF) based on said system reference data (YI REF, Y2REF, Y3REF, ... YHREF ), and correlation data (1 170, 1 180) indicative of a causal relationship between said system reference data (YI REF, Y2REF, Y3REF, ... YHREF ) and a corresponding desired first pump parameter value (X 1 REF, FIREF) indicative a desired operating point (205REF, 550REF, 550(r) REF) of the centrifugal pump (10; 10A; 10D) in relation to a Best Efficiency Point of operation; and generating, by a controller (755, 755C), said at least one set point parameter (UI SP, U2SP) based on at least one pump status parameter error value (XIERR, X2 ERR X3 ERR, X4 ERR); wherein said at least one pump status parameter error value (X 1 ERR, X2 ERR X3 ERR, X4 ERR) includes a first pump parameter error value (X IERR ) based on said generated first pump parameter reference value (XI REF, FIREF) and said first pump parameter value (XI , FI).

363. The method according to example 362 or according to any of the examples 326 to 361 or any preceding example; the method further comprising providing, by one or more hardware processors (350), to a user interface (210, 1200, 210S), data indicative of said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) for conveying to an operator (230) information about a current internal state (Y) of the fluid system (52, 40, 50, 56); and receiving, via a user interface (210, 1200, 210S), information indicative of said system reference data (YIREF, Y2REF, Y3REF, ... YHREF ) indicative of a desired fluid system internal state (Y EF).

364. The method according to any preceding example or according to any of the examples 326 to 363; wherein the fluid system (52, 40, 50, 56), or a part of the fluid system (52, 40, 50, 56), exhibits a natural frequency or at least one fluid system natural frequency.

365. The method according to example 364 or according to any preceding example or according to any of the examples 326 to 364; wherein said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) comprises a first fluid system parameter value (Y3; Y6) indicative of a first fluid system pulsation amplitude (Y3, Spy) having a first fluid system pulsation repetition frequency (Y4; Y7); and wherein said at least one pump status parameter value (Xl(r), FI(r); X2(r); X3(r); X4(r) ) comprises a fourth pump parameter value (X4) indicative of a first repetition frequency (IR) of said first fluid pressure pulsation (PFP); and wherein said first fluid system pulsation repetition frequency (Y4; Y7) is equal to said first repetition frequency (X4, fp).

366. The method according to example 365 when dependent on example 364 or according to any preceding example or according to any of the examples 326 to 365; wherein said fluid system analysis comprises the step of identifying a said fluid system natural frequency.

367. The method according to any preceding example or according to any of the examples 326 to 366; wherein said fluid system analysis includes an analysis of an amplitude relation (Y11) between a first fluid system parameter value (Y3) indicative of a first fluid system pulsation amplitude (Y3, SPY) having a first fluid system pulsation repetition frequency (Y4 ) and a second pump parameter value (X2, Sp) indicative of an amplitude of the first fluid pressure pulsation (PFP) having a first repetition frequency (fp); said first repetition frequency (fp) being a number of occurrences of a repeating event (Sp) per revolution of said impeller (20); wherein said first fluid system pulsation repetition frequency (Y4) is equal to said first repetition frequency (fp).

368. The method according to any preceding example or according to any of the examples 326 to 367; wherein said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) comprises a first amplitude relation value (Yl 1); said first amplitude relation value (Yl 1) being indicative of an amplitude relation (Yl 1) between a first fluid system parameter value (Y3) indicative of a first fluid system pulsation amplitude (Y3, Spy) having a first fluid system pulsation repetition frequency (Y4 ) and a second pump parameter value (X2, Sp) indicative of an amplitude of the first fluid pressure pulsation (PFP) having a first repetition frequency (fp); said first repetition frequency (fp) being a number of occurrences of a repeating event (Sp) per revolution of said impeller (20); wherein said first fluid system pulsation repetition frequency (Y4) is equal to said first repetition frequency (X4, fp).

369. The method according to any of examples 365 -368 when dependent on example 364 or according to any preceding example or according to any of the examples 326 to 365; wherein said at least one pump status parameter value (Xl(r), FI(r); X2(r); X3(r); X4(r) ) comprises a second pump parameter value (X2, Sp) indicative of an amplitude of the first fluid pressure pulsation (PFP) having a first repetition frequency (fp); said first repetition frequency (fp) being a number of occurrences of a repeating event (Sp) per revolution of said impeller (20); and said fluid system analysis comprises the step of generating a first fluid system parameter value (Y3; Y6) indicative of a first fluid system pulsation amplitude (Y3, Spy) having a first fluid system pulsation repetition frequency (Y4; Y7).

370. The method according to any of examples 365 -369 when dependent on example 364 or according to any preceding example or according to any of the examples 326 to 365; wherein said first amplitude relation value (Y11) has a magnitude that depends on said first repetition frequency (fp).

371. The method according to any of examples 365 -370 when dependent on example 364 or according to any preceding example or according to any of the examples 326 to 365; further comprising identifying a local maximum (Y1 Ipeak) of said first amplitude relation value (Y11), and identifying a certain repetition frequency value (fR RES); said certain repetition frequency value (fR RES) being a value of said first repetition frequency (fR) that is associated with said local maximum (Y1 Ipeak) of said first amplitude relation value (Y11); wherein said certain repetition frequency value (fR RES) is indicative of a fluid system resonance frequency.

372. The method according to any of examples 365 -371 when dependent on example 364 or according to any preceding example or according to any of the examples 326 to 365; wherein further comprising said rotation speed set point value (Ulsp, FROTSP) is generated based on said system reference data (YI REF, Y2REF, Y3 EF, ... YUREF ); and said at least one pump status parameter value (XI, FI; X2; X3; X4) such that said rotation speed set point value (Ulsp, FROTSP) sets an impeller rotational speed (Ul, FROT) that causes said first repetition frequency (X4, FR) to deviate from said fluid system resonance frequency value (FR RES).

373. The method according to any of examples 252 to 278; wherein said temporal relation value (FI, FI(r)) is a first pump parameter value (XI, FI) indicative a current operating point (205, 550, 550(r)) of the centrifugal pump (10; 10A; 10D) in relation to a Best Efficiency Point of operation.

374. The method according to any of the examples 326 to 373; wherein the method is for monitoring and/or operating a centrifugal pump (10; 10A; 10B; 10C; 10D) having a casing forming a volute (75) in which a rotatable impeller (20) is disposed for urging a fluid material (30) via the volute to a pump outlet (66) which is coupled to a fluid system (52) via a valve arrangement (VL; VH ).

375. The method according to example 374; wherein the valve arrangement (VL; VH ) is as defined in any of examples 252 to 278. 376. A method for monitoring and/or operating a centrifugal pump (10; 10A; 10B; 10C; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20), having a first number (L) of vanes (310), is disposed for urging a fluid material (30) via the volute to a pump outlet (66) which is coupled to a fluid system (52) via a valve arrangement (VL; VH ), the method comprising: receiving, by an apparatus (150, 150A, 450), a measuring signal indicative of a fluid pressure pulsation (PFP) in the fluid material (30); receiving, by said apparatus (150, 150A, 450), a reference signal indicative of a rotational reference position of said rotating impeller; generating, by said apparatus (150, 150A, 450), data indicative of an internal state of the centrifugal pump, said data including a phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)) based on a temporal relation between a repetitive reference position signal value (Ps, Pc, 1, 1C) and a repetitive signal event signature (Sp(r); Sp) whose repetition frequency ( FR) depends on said first number (L) when said first number (L) is higher than one.

377. The method according to any preceding example, further comprising analysing, e.g. by one or more sensors (70Y) and/or by one or more hardware processors (350), said fluid system (52, 40, 50, 56) so as to generate at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) based on said analysis; said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) being indicative of an internal state (Y) of the fluid system (52, 40, 50, 56); said fluid system internal state (Y) relating to pressure and/or flow of fluid (30) in said fluid system (52, 40, 50, 56).

378. The method according to example 377, wherein said pump status data (XI; X2; X3; X4; Xm) indicative of an internal state (X) of the centrifugal pump includes at least one pump status parameter value (XI ; X2; X3; X4; Xm); further comprising performing, by a correlator (150C; 150C1, 150C2, 15OC3), a correlation between said at least one pump status parameter value (XI; X2; X3; X4; Xm), and said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) so as to generate correlation data (1170, 1 180) indicative of a causal relationship between said at least one pump status parameter value (XI ; X2; X3; X4; Xm), and said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn).

379. The method according to example 378, wherein an individual pump status parameter value (XI ; X2; X3; X4; Xm) is indicative of an aspect of the internal state (X) of the pump (10), and an individual fluid system parameter value (Yl, Y2, Y3, ... Yn) is indicative of an aspect of the internal state (Y) in said fluid system (52, 40, 50, 56).

380. The method according to example 377 or 378 or 379 or according to any preceding example, wherein further comprising receiving at least one fluid system parameter reference value (Y I REF, Y2REF, Y3REF, ... YHREF ) indicative of a desired fluid system internal state (YREF); and generating at least one pump status parameter reference value (XI REF, X2REF, X3REF, X4REF, XITIREF); wherein said at least one pump status parameter reference value (XI REF, X2REF, X3REF, X4REF, XHIREF) is generated based on said system reference data (Y I REF, Y2REF, Y3REF, ... YHREF ), and correlation data (1170, 1 180) indicative of a causal relationship between said at least one pump status parameter reference value (X 1 REF, X2REF, X3REF, X4REF, XITIREF) and said at least one fluid system parameter reference value (Y 1 REF, Y2REF, Y3REF, ••• YOREF ).

381. The method according to any of examples 378 - 380, wherein said correlation data (1170, 1 180) is based on a regression analysis for identifying a linear relation that most closely, according to a mathematical criterion, fits a number of received pump status vectors (X(t)) of a first dimension (m) and a number of received corresponding fluid system vectors (Y(t)) of a second dimension (n), wherein said first dimension (m) is a positive integer larger than zero, and said second dimension (n) is a positive integer larger than zero.

382. The method according to any preceding example; wherein said fluid system analysis includes generating a first amplitude relation value (Y11); said first amplitude relation value ( Y 1 1) being indicative of a relation between a first fluid system parameter value (Y3) indicative of a first fluid system pulsation amplitude (Y3, Spy) having a first fluid system pulsation repetition frequency (Y4 ) and a second pump parameter value (X2, Sp) indicative of an amplitude of the first fluid pressure pulsation (PFP) having a first repetition frequency (fp); said first repetition frequency (fp) being a number of occurrences of a repeating event (Sp) per revolution of said impeller (20); wherein said first fluid system pulsation repetition frequency (Y4) is equal to said first repetition frequency (fp).

383. The method according to example 382; further comprising identifying a local maximum (Y1 Ipeak) of said first amplitude relation value (Y11), and identifying a certain repetition frequency value (fp RES); said certain repetition frequency value (fp RES) being a value of said first repetition frequency (fp) that is associated with said local maximum (Y1 Ipeak) of said first amplitude relation value (Y11); wherein said certain repetition frequency value (fp RES) is indicative of a fluid system resonance frequency.

384. The method according to any preceding example, wherein further comprising identifying a range of impeller speed values (X3, fpo-r), said identified impeller speed range including a certain impeller speed value (X3RES, fpoT RES) corresponding to said certain repetition frequency value (fp RES).

385. The method according to any preceding example, wherein further comprising said valve arrangement (VL; VH) comprises a flow control valve (VL; VH) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52) and/or for controlling another flow (QR), such as for example a return flow (QR); said another flow (QR) being diverted from flowing to the fluid system (52).

386. The method according to any preceding example, wherein further comprising receiving, e.g. via a user interface (210, 210S, 1200), information indicative of a desired system delivery flow (YI OREF, Q_OUTS_REF) and/or information indicative of a desired system delivery pressure (Y9REF, PS4S_REF); generating, based on said received information indicative of a desired system delivery flow (Y I OREF, Q_OUTS_REF) and/or information indicative of a desired system delivery pressure (Y9REF, P54S_REF), said rotation speed set point value (UI SP, f_ROTSP) for controlling a rotational speed (Ul, fpoT) of the impeller (20); comparing said rotation speed set point value (U 1 SP, 1'ROTSP) with said identified impeller speed range; and when said comparison indicates that said rotation speed set point value (UISP, f_ROTSP) corresponds to an impeller speed that is within said identified impeller speed range, then said rotation speed set point value (UI SP, fpoisp) is adjusted, e.g. by a control module (150B, 755), to a value that corresponds to an impeller speed that is outside of said identified impeller speed range.

387. The method according to example 386, wherein further comprising adjusting at least one valve in said valve arrangement (VL; VH) for controlling said system delivery flow (Y10, Q_OUTS) based on said adjusted rotation speed set point value (UI SP, f_ROTSP).

388. A method for monitoring and/or operating a pump (10; 10A; 10B; 10C; 10D) having a casing in which a rotatable part (20, 2000) is disposed for urging a fluid material (30) from an inlet to an outlet, the method comprising: receiving a measuring signal indicative of a vibration in the casing and/or a fluid pressure pulsation (PFP) in the fluid material (30); receiving a reference signal indicative of a rotational reference position of said rotating part (20, 2000); generating data indicative of an internal state of the pump, said data including a phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)) based on said measuring signal and said reference signal.

389. The method according example 388, wherein said temporal relation value (FI, FI(r)) is indicative of an internal state (205, 550, X)) of said pump (10).

390. The method according to any of examples 388-389, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point (205, 550; X) of the pump (10); and/or wherein said phase value (FI, FI(r), Xl(r)) is indicative of a current operating point (205, 550; X) of the pump (10).

391. The method according to any of examples 388-390, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point deviation (FIDEV; FIDEV(P+1); 550(p+l )) from a Best Efficiency Point of operation of the pump (10).

392. The method according to any of examples 388-391, further comprising displaying, on a user interface, the determined operation parameter (Ul, f_ROT; U2SP; VPSP) as a suggestion to a user.

393. The method according to any of examples 388-392, wherein said casing forms a chamber in which said rotatable part (2000) is disposed for rotating around an axis (60 ); said axis (60 ) being offset in relation to a centre of said chamber.

394. The method according to any of examples 388-393, wherein said fluid material (30) is in a gaseous phase, said rotatable part (2000) is an impeller (20); and said casing forms a chamber in which said rotatable impeller (20, 2000) disposed for rotating around an axis (60 ); said axis (60 ) being offset in relation to a centre of said chamber; and wherein, in operation, said chamber is partly filled with a liquid; and wherein, when said impeller (20) rotates at a speed (fuor) exceeding a certain limit speed value, then said liquid forms a ring so that the pump operates as a liquid ring pump; said liquid ring pump having an inlet for the gaseous material (30) and an outlet for the gaseous material (30).

395. The method according to any of examples 388-394, wherein said impeller (20) having a first number (L) of vanes or blades that co-operate with said liquid ring to form compartments; and wherein the compartments (Cl ), during operation of the pump, expand when communicating with said inlet so as to cause gaseous material (30) to enter the pump chamber, and wherein the compartments (C3), during operation of the pump, contract when communicating with said outlet so as to cause gaseous material (30) to exit the pump chamber, and wherein a compartment(C2), during operation of the pump, contracts when it does not communicate with said inlet or said outlet.

396. The method according to any of examples 388-395, further comprising the steps: generate, with a sensor, a measurement signal (SEA) dependent on mechanical movement caused by operation of the pump; generate, with a position sensor, a position signal indicative of a rotational position of said rotating part; record, with a signal recorder,

- a time sequence of measurement sample values (Se(i), S(j)) of said digital measurement signal (SEA, SMD), and

- a time sequence of said position signal values (P(i)), and

- time information (i, dt; j) such that an individual measurement sample value (S(j)) is associated with data indicative of time of occurrence of the individual measurement data value (S(j)), and such that an individual position signal value (P(i)) is associated with data indicative of time of occurrence of the individual position signal value (P(i)); detect, with a processor, the occurrence of an event, such as e.g. an amplitude peak value, in said recorded time sequence of measurement sample values (Se(i), S(j)); generate, with a processor, data indicative of an internal state of the pump, said data including a phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), Xl(r)) based on said measuring signal and said reference signal; and/or generate, with a processor, data indicative of said first temporal relation (XI ; FI(r), (r)) based on said detected event occurrence and said time sequence of measurement sample values (Se(i), S(j)).

397. The method according to example 396, further comprising detecting, by said apparatus (150, 150A, 450), in said measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)), occurrences of a signal event signature (Sp(r); Sp) having an event repetition frequency (fp) that depends on said first number (L) when said first number (L) is higher than one.

398. The method according to example 397, further comprising receiving, by said apparatus (150, 150A, 450), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution such that said reference position signal values (Ps, Pc, 1, 1C) have a certain occurrence frequency (fp), said certain occurrence frequency (fp) being equal to said event repetition frequency (fp).

399. The method according to example 397, further comprising generating, by said apparatus (150, 150A, 450), based on said reference signal (EP, P(i), P(j), P(q)), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution such that said reference position signal values (Ps, Pc, 1, 1C) have a certain occurrence frequency (fp), said certain occurrence frequency (fp) being equal to said event repetition frequency (fp). 400. The method according to any of examples 398-399, further comprising generating, by said apparatus (150, 150A, 450), based on said measuring signal and said reference signal, data (XI ; X2; X3; X4) indicative of said internal state (X) of the centrifugal pump (10); said internal state data (XI ; X2; X3; X4) including a temporal relation value (XI, Xl(r), FI, FI(r)) based on a temporal relation between said repetitive signal event signature (Sp(r); Sp) occurrences and said repetitive reference position signal value (Ps, Pc, 1, 1C) occurrences; wherein said temporal relation value (XI, Xl(r), FI, FI(r)) is indicative of an internal state (X) of the pump.

401. The method according to example 398, further comprising generating, by a device (170) such as for example an encoder, said time sequence of position signal sample values (P(i), P(j), P(q)) including said certain number (L) of reference position signal values (Ps, Pc, 1, 1C) per revolution of the impeller (20) or said certain number (L) of marker signals (Ps) per revolution of the impeller (20); and providing, by said device (170), said generated time sequence of position signal sample values (P(i), P(j), P(q)) for reception by said apparatus (150, 150A, 450).

402. The method according to example 399, further comprising receiving, by said apparatus (150, 150A, 450), said reference signal (Ep, P(i), P(j), P(q)) including a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a predetermined number of stationary reference positions (Ps) per impeller revolution; said predetermined number being one or more stationary reference positions (Ps) per impeller revolution; wherein said generating includes creating said time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of said certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution such that said reference position signal values (Ps, Pc, 1, 1C) have a certain occurrence frequency (TR.), said certain occurrence frequency ( R) being equal to said event repetition frequency (FR).

Claims

1. A system comprising: an apparatus (150, 150A, 450) for monitoring and/or controlling an internal state (X) of a centrifugal pump (10; 10A; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20), having a first number (L) of vanes (310), is disposed for urging a fluid (30) via the volute (75) to a pump outlet (66) for delivering a pump outlet flow (QOUT, Y2), thereby causing a fluid pressure pulsation (PFP, P54, +, -); a valve arrangement (Vi.; VH ) having a valve inlet (1222) which is connectable to a pump outlet (66, 54), and a first valve outlet (66D) for delivery of a system delivery flow (Y 10, Q_OUTS) of fluid to a fluid system (52, 40, 50, 56); a measurement sensor (70, 70s4, 70?7, 70₇₈, 330, 350, 450) for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of said fluid pressure pulsation (PFP, P54, +, - ); a device (170, 180, 330, 350, 450) for generating a reference signal indicative of a rotational reference position of a rotating impeller (20); wherein said apparatus (150, 150A, 450) is configured to detect, in said measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)), occurrences of a signal event signature (Sp(r); Sp) having an event repetition frequency (fp) that depends on said first number (L) when said first number (L) is higher than one; said apparatus (150, 150A, 450) is configured to receive or generate, based on said reference signal (Ep, P(i), P(j), P(q)), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution such that a reference position signal value (Ps, Pc, 1 , 1 C) has a certain occurrence frequency (fp), said certain occurrence frequency (fp) being equal to said event repetition frequency (fp); said apparatus (150, 150A, 450) is configured to generate, based on said measuring signal and said reference signal, data (XI; X2; X3; X4) indicative of said internal state (X) of the centrifugal pump (10); said internal state data (XI ; X2; X3; X4) including a temporal relation value (XI, XI (r), FI, FI(r)) based on a temporal relation between said repetitive signal event signature (Sp(r); Sp) occurrences and said repetitive reference position signal value (Ps, Pc, 1, 1C) occurrences; wherein said temporal relation value (XI, Xl(r), FI, FI(r)) is indicative of a current operating point (205, 550, 550(r)) of the pump in relation to a Best Efficiency Point of operation; a control module (150B, 755) configured to generate at least one set point parameter (U I SP, U2SP) based on said temporal relation value (XI, XI (r), FI, FI(r)); wherein said at least one set point parameter (U I SP, U2SP) comprises a rotation speed set point value (UI SP, FROTSP) for controlling a rotational speed (Ul, FROT) of the impeller (20); wherein said valve arrangement (VL; VH) comprises a first adjustable cross sectional area (AVLS ) for controlling said system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said valve arrangement (VL; VH) comprises a second adjustable cross sectional area (AVLR ) for controlling another flow (QR), such as for example a return flow (QR); said another flow (QR) being diverted from flowing to the fluid system (52), wherein said at least one set point parameter (UI SP, U2SP) comprises a first valve set point value (U2SP, U2ASP) for controlling said first adjustable cross sectional area (AVLS ) and/or said second adjustable cross sectional area (AVLR ), wherein when said temporal relation value (XI, Xl(r), FI, FI(r)) indicates a current operating point (205) with a lower pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said rotation speed set point value (UI SP, FROTSP) SO as to increase said impeller rotational speed (Ul, FROT), e.g. until said temporal relation value (XI, Xl(r), FI, FI(r)) indicates a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP); and said control module (150B, 755) is configured to adjust said first valve set point value (U2SP, U2ASP) so as to increase said another flow (QR) by increasing said second adjustable cross sectional area (AVLR ) and/or by decreasing said first adjustable cross sectional area (AVLS ).

2. The system according to claim 1, wherein when said temporal relation value (XI, Xl(r), FI, FI(r)) indicates a current operating point (205) with pump outlet flow (Y2, QOUT) at, or substantially at, Best Efficiency Point of pump outlet flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said first valve set point value (U2SP, U2ASP) so as to minimize, or eliminate, said another flow (QR) by decreasing said second adjustable cross sectional area (AVLR ) and/or by increasing said first adjustable cross sectional area (AVLS ).

3. The system according to any preceding claim, wherein when said temporal relation value (XI, Xl(r), FI, FI(r)) indicates a current operating point (205) with a flow at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is higher than to a desired system delivery flow (Y I OREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said rotation speed set point value (Ulsp, f_ROTSP) so as to decrease said impeller rotational speed (Ul, FROT), e.g. until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF).

4. The system according to claim 1, wherein when said temporal relation value (XI, Xl(r), FI, FI(r)) indicates a current operating point (205) with a pump outlet fluid flow (Y2, QOUT) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF); then said control module (150B, 755) is configured to adjust said first valve set point value (U2SP, U2ASP) so as to minimize said another flow (QR), and said control module (150B, 755) is configured to adjust said rotation speed set point value (UISP, FROTSP) SO as to control said impeller rotational speed (Ul, f_ROT) so as to maintain said temporal relation value (XI, Xl(r), FI, FI(r)) indicating a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP).

5. The system according to any preceding claim, wherein said valve arrangement (VL; VH) comprises a flow control valve (VH) having a third adjustable cross sectional area (AVHS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said at least one set point parameter (U 1 SP, U2SP) comprises a second valve set point value (U2SP, U2BSP) for controlling said third adjustable cross sectional area (AVHS ).

6. The system according to claim 5, wherein when said temporal relation value (XI, X 1 (r), FI, FI(r)) indicates a current operating point (205) with a higher pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), then said control module (150B, 755) is configured to adjust said second valve set point value (U2SP, U2BSP) so as to reduce said third adjustable cross sectional area (AVHS ).

7. The system according to any of claims 1-4, wherein when said temporal relation value (XI, XI (r), FI, FI(r)) indicates a current operating point (205) with a higher pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), then said control module (150B, 755) is configured to adjust a valve set point value (U2YIOSP; U2SP, U2ASP, U2BSP) SO as to reduce said first adjustable cross sectional area (AVHS, AVLS) for reducing said system delivery flow (Y 10, Q_OUTS) to the fluid system (52).

8. The system according to any preceding claim, wherein said valve arrangement (VL; VH ) has a second valve outlet for said another flow (QR).

9. The system according to any preceding claim, wherein wherein said measurement sensor (70, 70s4, 70?7, 70₇₈, 70925, 7O955, 330, 350, 450) is mountable or attachable so as to detect said fluid material pulsation (PFP, P54, +, -) in said pump outlet flow (QOUT, Y2) or in said volute (75); or said measurement sensor (70, 7054, 70?7, 7078, 70925, 7O955, 330, 350, 450) is mountable or attachable so as to generate a measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)) having an amplitude that depends on said fluid material pulsation (PFP) in said pump outlet flow (QOUT, Y2) or in said volute (75).

10. The system according to any preceding claim, wherein said measurement sensor (70, 7O54, 70?7, 7078, 7O925, 7O955, 330, 350, 450) is a vibration sensor positioned and configured for detecting vibrations having a direction (955) of movement perpendicular to, or substantially perpendicular to, a straight line (923) between a tip of a tongue (65) and an axis (60) of impeller rotation; wherein said measurement sensor (70, 7O925, 7O955, 330, 350, 450) is firmly attachable, or attached, on a bearing (925) of a pump shaft (710), or said measurement sensor (70, 70?7, 7078, 7O955, 330, 350, 450) is firmly attachable, or attached, on an outer surface of the pump casing (62).

1 1. A method for monitoring and/or operating a centrifugal pump (10; 10A; 10B; 10C; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20), having a first number (L) of vanes (310), is disposed for urging a fluid material (30) via the volute to a pump outlet (66) which is coupled to a fluid system (52) via a valve arrangement (VL; VH ), the method comprising: receiving, by an apparatus (150, 150A, 450), a measuring signal indicative of a fluid pressure pulsation (PFP) in the fluid material (30); receiving, by said apparatus (150, 150 A, 450), a reference signal indicative of a rotational reference position of said rotating impeller; generating, by said apparatus (150, 150A, 450), data (XI ; X2; X3; X4) indicative of an internal state (X) of the centrifugal pump, said data including a phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, Fl(r), XI (r)) based on a temporal relation between a repetitive reference position signal value (Ps, Pc, 1, 1C) and a repetitive signal event signature (Sp(r); Sp) whose repetition frequency (fk) depends on said first number (L) when said first number (L) is higher than one; wherein said phase value (FI, FI(r), XI (r)) is indicative of a current operating point of the pump in relation to a Best Efficiency Point of operation, and/or wherein said temporal relation value (FI, FI(r), XI (r)) is indicative of a current operating point of the pump in relation to a Best Efficiency Point of operation; generating at least one set point parameter (Ulsp, U2SP) based on said phase value (FI, FI(r), Xl(r)) and/or a temporal relation value (FI, FI(r), XI (r)); wherein said at least one set point parameter (Ulsp, U2SP) comprises a rotation speed set point value (Ulsp, FROTSP) for controlling a rotational speed (Ul, FROT) of the impeller (20).

12. The method according to claim 11, wherein said rotation speed set point value (U 1 SP, FROTSP) affects pump outlet fluid pressure (Yl, P54) and/or pump outlet fluid flow (Y2, QOUT) at said pump outlet (66), and wherein said rotation speed set point value (Ulsp, FROTSP) is based on a desired system delivery flow (YIOREF, Q_OUTSREF) and on said phase value (FI, FI(r), Xl(r)) and/or temporal relation value (FI, FI(r), Xl(r)).

13. The method according to claim 1 1 or 12, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow, then said rotation speed set point value (Ulsp, FROTSP) is adjusted to increase said impeller rotational speed (Ul, FROT).

14. The method according to claim 11, 12 or 13, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a lower flow than Best Efficiency Point of flow, then said rotation speed set point value (Ulsp, FROTSP) is adjusted to increase said impeller rotational speed (Ul, FROT) until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YI OREF, Q_OUTSREF).

15. The method according to any of claims 1 1-14, wherein said a valve arrangement (VL; VH) comprises a flow control valve (VL; VH) having a first adjustable cross sectional area (AVLS; AVHS) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said at least one set point parameter (UI SP, U2SP) comprises a first valve set point value (U2SP, U2Asp) for controlling said first adjustable cross sectional area (AVLS; AVHS).

16. The method according to any of claims 1 1-15, wherein said valve arrangement (VL; VH) comprises a first adjustable cross sectional area (AVLS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said valve arrangement (VL; VH) comprises a second adjustable cross sectional area (AVLR ) for controlling another flow (QR), such as for example a return flow (QR); said another flow (QR) being diverted from flowing to the fluid system (52), wherein said at least one set point parameter (U I SP, U2sp) comprises a first valve set point value (U2SP, U2ASP) for controlling said first adjustable cross sectional area (AVLS ) and/or said second adjustable cross sectional area (AVLR ).

17. The method according to any of claims 15 or 16, wherein said first valve set point value (U2SP, U2ASP) is initially set so that said system delivery flow (Y10, Q_OUTS) is equal to said pump outlet fluid flow (Y2, QOUT).

18. The method according to any of claims 15 to 17, wherein when said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) with a lower pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (YIOREF, Q_OUTSREF); then said rotation speed set point value (UISP, f_ROTSP) is adjusted to increase said impeller rotational speed (Ul, f_ROT), e.g. until said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said first valve set point value (U2SP, U2ASP) is adjusted so as to increase said another flow (QR) .

19. The method according to any of claims 15 - 18, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with pump outlet flow (Y2, QOUT) at, or substantially at, Best Efficiency Point of pump outlet flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y 10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF); then said first valve set point value (U2SP, U2ASP) is adjusted so as to minimize, or eliminate, said another flow (QR).

20. The method according to any of claims 15 - 19, wherein when said phase value (FI, FI(r), XI (r)) indicates a current operating point (205) with a flow at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is higher than to a desired system delivery flow (YI OREF, Q_OUTSREF); then said rotation speed set point value (U 1 SP, f_ROTSP) is adjusted to decrease said impeller rotational speed (Ul, IROT), e.g. until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF).

21. The method according to any of claims 15 - 20, wherein said valve arrangement (VL; VH) comprises a flow control valve (VH) having a third adjustable cross sectional area (AVHS ) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52), and wherein said at least one set point parameter (UI SP, U2SP) comprises a second valve set point value (U2SP, U2BSP) for controlling said third adjustable cross sectional area (AVHS ).

22. The method according to any of claims 15 - 21, wherein when said phase value (FI, FI(r), X 1 (r)) indicates a current operating point (205) with a higher pump outlet fluid flow (Y2, QOUT) than Best Efficiency Point of flow (Q_OUTBEP), then said second valve set point value (U2SP, U2BSP) is adjusted so as to reduce said third adjustable cross sectional area (AVHS )•

23. The method according to any of claims 15 - 22, wherein when said phase value (FI, FI(r), Xl(r)) indicates a current operating point (205) with a flow at, or substantially at, Best Efficiency Point of flow (Y2BEP, Q_OUTBEP), and said system delivery flow (Y10, Q_OUTS) is lower than to a desired system delivery flow (YI OREF, Q_OUTSREF); then said rotation speed set point value (Ulsp, f_ROTSP) is adjusted to increase said impeller rotational speed (Ul, fRoi), e.g. until said system delivery flow (Y10, Q_OUTS) corresponds to a desired system delivery flow (Y I OREF, Q_OUTSREF).

24. The method according to any of claims 11 - 23, wherein said phase value (FI, FI(r), X 1 (r)) is a temporal relation value (FI, FI(r)).

25. The method according to any of claims 1 1 - 24, wherein said temporal relation value (FI, FI(r)) is indicative of a current operating point deviation (FIDEV; FIDEV(P+1 ); 550(p+ 1 )) from a Best Efficiency Point of operation of the centrifugal pump (10).

26. The method according to any of claims 11 - 25, further comprising displaying, on a user interface, said at least one set point parameter (UI SP, U2SP; U2ASP; U2BSP) as a suggestion to a user.

27. The method according to any of claims 11 - 26, wherein said at least one set point parameter (UI SP, U2SP; U2ASP; U2BSP) is based on a desired temporal relation value (FIREF, FIREFW, XI REF), said desired temporal relation value (FIREF, FlREF(r), XI REF) being indicative of a desired pump operating point (205REF, 550 REF; XI REF (0).

28. The method according to any of claims 11 - 27, wherein said rotation speed set point value (U 1 SP, f_ROTSP) is based on a desired impeller rotational speed (UI REF, FROTREF, X3REF).

29. The method according to any of claims 11 - 28, wherein said rotation speed set point value (UI SP, FROTSP) is based on a desired impeller rotational speed (UIREF, f_ROTREF, X3REF), said desired impeller rotational speed (UIREF, FROTREF, X3REF) being indicative of a desired flow (Y2REF, QOUT_REF, Q_OUTS_REF) and/or a desired Head (YIREF, P54REF).

30. The method according to any of claims 15 - 29, wherein adjusting the first valve set point value (U2SP, U2ASP) occurs during operation of the pump.

31. The method according to claim 21 or any of claims 22 - 30 when including claim 21, wherein adjusting the second valve set point value (U2SP, U2BSP) occurs during operation of the pump.

32. The method according to any of claims 16 - 31, wherein the another flow (QOUTR) is a return flow for returning fluid to a fluid storage or to an inlet side of the pump (10).

33. The method according to any preceding claim, further comprising detecting, by said apparatus (150, 150A, 450), in said measurement signal (SFP; SEA, SMD, Se(i), S(j), S(q)), occurrences of a signal event signature (Sp(r); Sp) having an event repetition frequency (fpt) that depends on said first number (L) when said first number (L) is higher than one.

34. The method according to claim 33, further comprising receiving, by said apparatus (150, 150A, 450), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution such that said reference position signal values (Ps, Pc, 1 , 1 C) have a certain occurrence frequency (fp), said certain occurrence frequency (TR) being equal to said event repetition frequency (IR).

35. The method according to claim 33, further comprising generating, by said apparatus (150, 150A, 450), based on said reference signal (Ep, P(i), P(j), P(q)), a time sequence of position signal sample values (P(i), P(j), P(q)) indicative (Ps, Pc, 1, 1C) of a certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution such that said reference position signal values (Ps, Pc, 1, 1C) have a certain occurrence frequency (IR), said certain occurrence frequency (PR) being equal to said event repetition frequency (PR).

36. The method according to claim 34 or 35, further comprising generating, by said apparatus (150, 150A, 450), based on said measuring signal and said reference signal, data (XI; X2; X3; X4) indicative of said internal state (X) of the centrifugal pump (10); said internal state data (XI; X2; X3; X4) including a temporal relation value (XI, Xl(r), FI, FI(r)) based on a temporal relation between said repetitive signal event signature (Sp(r); Sp) occurrences and said repetitive reference position signal value (Ps, Pc, 1, 1C) occurrences; wherein said temporal relation value (XI, Xl(r), FI, FI(r)) is indicative of a current operating point (205, 550, 550(r)) of the pump in relation to a Best Efficiency Point of operation.

37. The method according to claim 34, further comprising generating, by a device (170) such as for example an encoder, said time sequence of position signal sample values (P(i), P(j), P(q)) including said certain number (L) of reference position signal values (Ps, Pc, 1, 1C) per revolution of the impeller (20) or said certain number (L) of marker signals (Ps) per revolution of the impeller (20); and providing, by said device (170), said generated time sequence of position signal sample values (P(i), P(j), P(q)) for reception by said apparatus (150, 150A, 450).

38. The method according to claim 35, further comprising receiving, by said apparatus (150, 150A, 450), said reference signal (Ep, P(i), PC), P(q)) including a time sequence of position signal sample values (P(i), PC), P(q)) indicative (Ps, Pc, 1, 1C) of a predetermined number of stationary reference positions (Ps) per impeller revolution; said predetermined number being one or more stationary reference positions (Ps) per impeller revolution; wherein said generating includes creating said time sequence of position signal sample values (P(i), PC), P(q)) indicative (Ps, Pc, 1, 1C) of said certain number (L) of stationary reference positions (Ps, Pc, Pl, P2, P3, P4, P5, PL) per impeller revolution such that said reference position signal values (Ps, Pc, 1, 1C) have a certain occurrence frequency (FR), said certain occurrence frequency (f«) being equal to said event repetition frequency (FR).

39. The method according to any preceding claim, further comprising analysing, e.g. by one or more sensors (70Y) and/or by one or more hardware processors (350), said fluid system (52, 40, 50, 56) so as to generate at least one fluid system parameter value (Yl , Y2, Y3, ... Yn) based on said analysis; said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn) being indicative of an internal state (Y) of the fluid system (52, 40, 50, 56); said fluid system internal state (Y) relating to pressure and/or flow of fluid (30) in said fluid system (52, 40, 50, 56).

40. The method according to claim 39, wherein said pump status data (XI ; X2; X3; X4; Xm) indicative of an internal state (X) of the centrifugal pump includes at least one pump status parameter value (XI ; X2; X3; X4; Xm); further comprising performing, by a correlator (150C; 150C1, 150C2, 150C3), a correlation between said at least one pump status parameter value (XI ; X2; X3; X4; Xm), and said at least one fluid system parameter value (Yl , Y2, Y3, ... Yn) so as to generate correlation data (1 170, 1 180) indicative of a causal relationship between said at least one pump status parameter value (XI ; X2; X3; X4; Xm), and said at least one fluid system parameter value (Yl, Y2, Y3, ... Yn).

41 . The method according to claim 40, wherein an individual pump status parameter value (XI ; X2; X3; X4; Xm) is indicative of an aspect of the internal state (X) of the pump (10), and an individual fluid system parameter value (Yl , Y2, Y3, ... Yn) is indicative of an aspect of the internal state (Y) in said fluid system (52, 40, 50, 56).

42. The method according to claim 39 or 40 or 41 or according to any preceding claim, wherein further comprising receiving at least one fluid system parameter reference value (YIREF, Y2REF, Y3REF, ... YnREF ) indicative of a desired fluid system internal state (YREF); and generating at least one pump status parameter reference value (XI REF, X2REF, X3REF, X4REF, XITIREF); wherein said at least one pump status parameter reference value (XI REF, X2REF, X3REF, X4REF, XUIREF) is generated based on said system reference data (Y I REF, Y2REF, Y3REF, ... YHREF ), and correlation data (1 170, 1 180) indicative of a causal relationship between said at least one pump status parameter reference value

(XI REF, X2REF, X3REF, X4REF, XITIREF) and said at least one fluid system parameter reference value (Y I REF, Y2REF, Y3REF, ... YnREF ).

43. The method according to any of claims 40 - 42, wherein said correlation data (1170, 1 180) is based on a regression analysis for identifying a linear relation that most closely, according to a mathematical criterion, fits a number of received pump status vectors (X(t)) of a first dimension (m) and a number of received corresponding fluid system vectors (Y(t)) of a second dimension (n), wherein said first dimension (m) is a positive integer larger than zero, and said second dimension (n) is a positive integer larger than zero.

44. The method according to any preceding claim; wherein said fluid system analysis includes generating a first amplitude relation value (Y1 1 ); said first amplitude relation value (Y1 1) being indicative of a relation between a first fluid system parameter value (Y3) indicative of a first fluid system pulsation amplitude (Y3, Spy) having a first fluid system pulsation repetition frequency (Y4 ) and a second pump parameter value (X2, Sp) indicative of an amplitude of the first fluid pressure pulsation (PFP) having a first repetition frequency (fk); said first repetition frequency (fp) being a number of occurrences of a repeating event (Sp) per revolution of said impeller (20); wherein said first fluid system pulsation repetition frequency (Y4) is equal to said first repetition frequency (FR).

45. The method according to claim 44; further comprising identifying a local maximum (Y1 Ipeak) of said first amplitude relation value (Y11), and identifying a certain repetition frequency value (FR RES); said certain repetition frequency value (FR RES) being a value of said first repetition frequency (FR) that is associated with said local maximum (Y1 Ipeak) of said first amplitude relation value (Y11); wherein said certain repetition frequency value (FR RES) is indicative of a fluid system resonance frequency.

46. The method according to any preceding claim, wherein further comprising identifying a range of impeller speed values (X3, FROT), said identified impeller speed range including a certain impeller speed value (X3RES, FROT_RES) corresponding to said certain repetition frequency value (FR RES).

47. The method according to any preceding claim, wherein further comprising said valve arrangement (VL; VH) comprises a flow control valve (VL; VH) for controlling a system delivery flow (Y10, Q_OUTS) to the fluid system (52) and/or for controlling another flow (QR), such as for example a return flow (QR); said another flow (QR) being diverted from flowing to the fluid system (52).

48. The method according to any preceding claim, wherein further comprising receiving, e.g. via a user interface (210, 210S, 1200), information indicative of a desired system delivery flow (Y I OREF, Q_OUTS_REF) and/or information indicative of a desired system delivery pressure (Y9 EF, P54S_REF); generating, based on said received information indicative of a desired system delivery flow (YIOREF, Q_OUTS REF) and/or information indicative of a desired system delivery pressure (Y9REF, PS4S_REF), said rotation speed set point value (UI SP, FROTSP) for controlling a rotational speed (Ul, FROT) of the impeller (20); comparing said rotation speed set point value (Ulsp, FROTSP) with said identified impeller speed range; and when said comparison indicates that said rotation speed set point value (U 1 SP, TROTSP) corresponds to an impeller speed that is within said identified impeller speed range, then said rotation speed set point value (U I SP, TROTSP) is adjusted, e.g. by a control module (150B, 755), to a value that corresponds to an impeller speed that is outside of said identified impeller speed range.

49. The method according to claim 48, wherein further comprising adjusting at least one valve in said valve arrangement (VL; VH) for controlling said system delivery flow (Y10, Q_OUTS) based on said adjusted rotation speed set point value (UI SP, fROTSP).

50. A computer program, loadable into a digital memory of an apparatus (150) having a data processor (350), the computer program comprising computer program code (380, 394, 410) adapted to perform the steps of the method according to any preceding claim when said computer program is run on a data processor.

51 . The computer program according to claim 50, the computer program being embodied on a computer readable medium.

52. An apparatus for monitoring and/or operating a centrifugal pump (10) and/or a fluid system (52), the apparatus being configured to perform the method according to any preceding claim.

53. The apparatus according to claim 35, further comprising one or more hardware processors (350) configured to perform the method according to any preceding claim.

54. A kit of parts for monitoring and/or controlling an internal state (X) of a centrifugal pump (10; 10A; 10D) having a casing (62) forming a volute (75) in which a rotatable impeller (20), having a first number (L) of vanes (310), is disposed for urging a fluid (30) via the volute (75) to a pump outlet (66) for delivering a pump outlet flow (QOUT, Y2); the kit of parts comprising: an apparatus (150, 150A, 450) for monitoring an internal state (X) of a centrifugal pump (10; 10A); a valve arrangement (VL; VH ) having a valve inlet (1222) which is connectable to a pump outlet (66, 54), and a first valve outlet (66D) for delivery of a system delivery flow (Y10, Q_OUTS) of fluid to a fluid system (52, 40, 50, 56); a control module (150B, 755) for controlling a rotational speed (Ul, I'ROT) of the impeller 20 and for controlling the valve arrangement so as to control the system delivery flow (Y10, Q_OUTS).

55. The kit of parts according to claim 54, further comprising: a measurement sensor (70) for generating a measuring signal (SFP; SEA, SMD, Se(i), S(j), S(q)) indicative of fluid pressure pulsation (PFP, P54, +, -); a device (170, 180) for generating a reference signal indicative of a rotational reference position of a rotating impeller (20) in the pump (10).