EP2500579A1 - Détection de la cavitation et de l'entraînement de gaz dans une pompe électrique centrifuge - Google Patents

Détection de la cavitation et de l'entraînement de gaz dans une pompe électrique centrifuge Download PDF

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Publication number
EP2500579A1
EP2500579A1 EP11158738A EP11158738A EP2500579A1 EP 2500579 A1 EP2500579 A1 EP 2500579A1 EP 11158738 A EP11158738 A EP 11158738A EP 11158738 A EP11158738 A EP 11158738A EP 2500579 A1 EP2500579 A1 EP 2500579A1
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EP
European Patent Office
Prior art keywords
monitoring module
pump
cavitation
values
centrifugal pump
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP11158738A
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German (de)
English (en)
Inventor
Helmut Henzler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Priority to EP11158738A priority Critical patent/EP2500579A1/fr
Publication of EP2500579A1 publication Critical patent/EP2500579A1/fr
Withdrawn legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
    • F04D15/0088—Testing machines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
    • F04D15/02—Stopping of pumps, or operating valves, on occurrence of unwanted conditions
    • F04D15/0209—Stopping of pumps, or operating valves, on occurrence of unwanted conditions responsive to a condition of the working fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
    • F04D15/02—Stopping of pumps, or operating valves, on occurrence of unwanted conditions
    • F04D15/0209—Stopping of pumps, or operating valves, on occurrence of unwanted conditions responsive to a condition of the working fluid
    • F04D15/0218—Stopping of pumps, or operating valves, on occurrence of unwanted conditions responsive to a condition of the working fluid the condition being a liquid level or a lack of liquid supply
    • F04D15/0236—Lack of liquid level being detected by analysing the parameters of the electric drive, e.g. current or power consumption
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/669—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for liquid pumps

Definitions

  • the invention relates to a method for monitoring a centrifugal pump driven by an electric motor, in which the power consumption or the load current of the electric motor is determined and values derived therefrom are fed to a pump monitoring module according to the preamble of claim 1. Furthermore, the invention relates to an arrangement with a pump monitoring module according to FIG the preamble of claim 9 for carrying out such a method.
  • a centrifugal pump is a turbomachine, wherein by means of a rotating impeller, a fluid, usually a liquid, is moved. Incoming medium entering through an access line is entrained by the rotating impeller, d. H. accelerated. The accelerated fluid then exits via a drain line from the centrifugal pump.
  • the drive of the centrifugal pump is usually carried out by an electric motor.
  • a method for preventing dry running in a centrifugal pump is known. This occurs when the centrifugal pump is insufficiently supplied with liquid pumped medium. Dry running of a centrifugal pump can occur, for example, if valves on the intake side are inadvertently connected or if a liquid reservoir in front of the access line has run empty. Since dry running can quickly lead to overheating of the pump components, in particular of mechanical seals, a method for detecting and avoiding dry running in a centrifugal pump is described there.
  • centrifugal pumps In the operation of centrifugal pumps, however, may still other disorders occur, which, if they are longer, to a Damage to the pump can lead or optimal driving style of a process in which the centrifugal pump is used, are detrimental. Examples include an entrainment of gas or cavitation in a funded liquid medium. Cavitation can even cause a material removal on the impeller of the centrifugal pump after a longer exposure time. When a gas Mit assume the flow rate of the pump decreases.
  • the invention is therefore based on the object to find a technical solution that allows monitoring of a driven by an electric motor centrifugal pump on co-promotion of gas or cavitation in a subsidized liquid medium.
  • the invention is based on the finding that the gas bubbles imploding during cavitation as well as the gas bubbles compressed in the co-transport of gas cause impact torques on the blades of the impeller, which are detectable in the drive as torque pulses. Since the power consumption or the load current of the electric motor is decisive for the formation of torque, their values can advantageously be determined and evaluated for the purpose of detecting such pulses. Since values of the power consumption or of the load current usually exist in motor control systems in any case, this has the advantage that no additional sensors are required for monitoring the centrifugal pump.
  • the reliability of the diagnostic statement is further improved by the threshold value used for comparison being adapted to the specific model.
  • the threshold value used for comparison being adapted to the specific model.
  • a more accurate classification of the cause of the fault is also made, ie, it is distinguished between the cause of the fault entrainment of gas and the cause of the fault cavitation.
  • spectral amplitude values in a second predetermined frequency band which is separated from the first frequency band of the first indicator variable, are calculated as a second indicator variable in the frequency domain. If the second indicator size deviates greatly from the first indicator size, this indicates a presence of gas in the pumped liquid medium, otherwise cavitation is likely to cause the disturbance.
  • Due to the hydraulic conditions on the impeller of the centrifugal pump namely expressing entrainment of gas and cavitation different in frequency range. Cavitation caused by torque pulses are relatively broadband in the frequency range, while by entrainment of gas signal components are rather narrow band around the rotational frequency of the motor current around increased.
  • This finding can be used in a further advantageous embodiment to increase the reliability of the diagnosis statement by means of a statistical evaluation of the signal components in a plurality of comparatively narrow frequency bands. If the standard deviation of the signal components exceeds a third predetermined threshold value, entrainment of gas in the liquid medium is indicated, otherwise the presence of cavitation.
  • Another possibility for evaluating the signal components is an envelope method in which an amplitude curve described by a polynomial is applied via the amplitudes of the individual spectral lines in the frequency domain, the polynomial parameters of which are used as indicator quantities.
  • a control system of a process plant, in which the centrifugal pump is used can also be supplemented by a way to assess the condition of the centrifugal pump, which is important for improving plant operation, for example in the sense of preventive maintenance to avoid unnecessary plant downtime.
  • the pump monitoring module uses the first indicator size to grading a determined cavitation into different levels of cavitation intensity. With a larger indicator size, a stronger cavitation level is assigned. Operating times of the centrifugal pump are weighted with the respectively determined for these stages of cavitation and estimated the remaining life of the centrifugal pump based on the occurred during their previous operation total load.
  • a widely used type of drive for centrifugal pumps is the asynchronous motor with squirrel cage rotor. Since the stator current is decisive for the torque generation of the motor, it is possible to detect disturbances, in particular due to increased amplitude values of the spectral lines, which are close to the rotational frequency of the stator current. In the case of the frequent case of an asynchronous motor, such determination of the first frequency range is therefore particularly well suited for being adjacent to the rotational frequency of the load current, which is referred to here as the stator current, but does not include the rotational frequency itself. This frequency range can additionally be mirrored around the rotational frequency, so that it consists of two bands, which are arranged in mirror image to the rotational frequency exists.
  • the method is preferably implemented in software or in a combination of software / hardware, so that the invention also relates to a computer program with computer-executable program code instructions for implementing the method.
  • the invention also relates to a computer program product, in particular a data carrier or a storage medium, with a computer program executable by a computer.
  • a computer program is preferably part of the process control system or is kept in a memory of the process control system or can be loaded into this memory, so that during operation of the process control system it automatically performs the pump monitoring according to the method.
  • a pump monitoring module PÜB has an evaluation unit AE, a memory SP connected to the evaluation unit AE and an input / output unit EA likewise connected to the evaluation unit AE.
  • the pump monitoring module PÜB is connected to a motor module MBS.
  • the pump monitoring module PÜB and the motor module MBS are part of a process control system PLS, for example a SIMATIC PCS7.
  • An engine control unit MSTG is connected to the engine block MBS, the evaluation unit AE of the pump monitoring module PÜB and to an electric motor M.
  • the electric motor M drives a centrifugal pump P.
  • the centrifugal pump P is supplied with liquid conveying medium via a supply line ZL and pumps out the pumped medium via a drain line AL. Data traffic between the mentioned components is indicated by arrows.
  • the power consumption of the electric motor M from the engine control unit MSTG continuously with high sampling rate, z. B. 400 kHz, and passed in the form of a temporal sequence of digital values to the evaluation unit AE of the pump monitoring module PÜB.
  • the digital values of the current consumption which represent the power consumption or the load current of the electric motor M, are subjected to a fast Fourier transformation (FFT) in order to determine signal components of the digital values in different frequency ranges.
  • FFT fast Fourier transformation
  • predetermined threshold values are still required, which are stored in the memory SP.
  • the respective diagnosis result is indicated by a signal by means of the input / output unit EA.
  • FIG. 2 Based FIG. 2 the sequence of the method for monitoring a centrifugal pump driven by an electric motor is explained in more detail below.
  • the first indicator variable K1 is obtained, which is significant for distinguishing between normal operation and interference-prone operation by gas promotion or cavitation.
  • the first indicator quantity K1 is calculated on the basis of the signal components in a frequency range composed of the subregions between 40.2 and 48 Hz and between 52 and 59.8 Hz.
  • the distinction between normal operation and faulty operation is made in a subsequent step S3, in which the first indicator variable K1 is compared with a first threshold SW1 associated therewith.
  • the first threshold SW1 is on-hand previously predetermined calculations of the first indicator size K1 in normal operation, for example, by multiplying the mean value of the indicator variable K1 calculated from several measurements by a factor of 1.3.
  • the indicator variable K1 is predetermined in such a way that it lies a small distance above the highest value of the first indicator variable K1 determined in normal operation. Since the first threshold value is determined on the same centrifugal pump on which the diagnosis is carried out later, it is thus adapted to the specific model and manufacturing variations advantageously have no influence on the reliability of the diagnostic statement.
  • step S4 is entered. This transition is in FIG. 2 marked by a "J" at the transitional arrow. If, on the other hand, the first indicator size K1 is not greater than the first threshold value SW1, then, according to an arrow marked "N", a step S5 is entered in which a signal indicates that the pump is in normal operation and there is no disturbance that would be caused by Gasmit programme or cavitation.
  • a second indicator quantity K2 is calculated in step S4, which results as the sum of the signal components in the frequency ranges 32.2 to 40 Hz and 60 to 67.8 Hz.
  • the formula used for this differs from the above calculation formula for K1 only in terms of the summation limits.
  • a subsequent step S6 it is checked whether the difference between the first indicator size K1 and the second indicator size K2 is smaller than a second predetermined threshold value SW2. If this is the case, a transitional arrow labeled "J" is used to proceed to a step S7 in which, depending on the size of the first indicator variable K1, a cavitation in FIG one of three different strength levels is displayed.
  • step S8 a signal causes a disturbance due to entrainment of gas is displayed in the conveyed liquid medium. Due to the hydraulic conditions on the impeller of the centrifugal pump, namely, a entrainment of gas and a cavitation in the spectral components in the frequency range expressed differently. In cavitation, the spectral signal components decrease with increasing distance to the rotational frequency of the stator current of an asynchronous motor weaker than mitzhouördertem gas. Therefore, the above calculated difference of the two indicator sizes K1 and K2 in the case of entrainment of gas is greater than in the case of cavitation. In the manner described, it is thus easy to make a distinction between the two causes of the fault.
  • 2 described embodiment is still called a procedure in which an envelope is placed over the spectral signal components in a predetermined frequency range and by a polynomial is approximated.
  • the polynomial parameters can then be used as indicator quantities.
  • a pump monitoring module can be embodied within the engine module or within the engine control unit. It is also not essential to the invention in which component the evaluation of the power consumption or the load current or the determination of the various threshold values takes place.
  • the evaluation unit or the memory may also be arranged outside the pump monitoring module, in which case the evaluation unit or memory must of course be connected to the pump monitoring module.
  • Engine control units in which often the functions of a motor starter, a soft starter and / or an engine management system are realized, have their own arithmetic unit and can realize the evaluation described above in addition to the actual control task and pass the calculated indicator sizes to a control system.
  • the engine block for the invention is not mandatory, but usually available in process control systems.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Non-Positive-Displacement Pumps (AREA)
EP11158738A 2011-03-17 2011-03-17 Détection de la cavitation et de l'entraînement de gaz dans une pompe électrique centrifuge Withdrawn EP2500579A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP11158738A EP2500579A1 (fr) 2011-03-17 2011-03-17 Détection de la cavitation et de l'entraînement de gaz dans une pompe électrique centrifuge

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP11158738A EP2500579A1 (fr) 2011-03-17 2011-03-17 Détection de la cavitation et de l'entraînement de gaz dans une pompe électrique centrifuge

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EP2500579A1 true EP2500579A1 (fr) 2012-09-19

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019034426A2 (fr) 2017-08-15 2019-02-21 KSB SE & Co. KGaA Procédé de protection contre la cavitation en cas de cyberattaques et unité pour mettre en oeuvre ce procédé
WO2019096545A1 (fr) 2017-11-15 2019-05-23 KSB SE & Co. KGaA Procédé et dispositif de protection contre des cyberattaques de groupes motopompes
WO2021227221A1 (fr) * 2020-05-09 2021-11-18 蜂巢动力系统(江苏)有限公司 Procédé de protection contre la marche à sec pour pompe à eau électrique
EP4372221A1 (fr) * 2022-11-18 2024-05-22 Cattron North America, Inc. Détection de cavitation à l'aide d'une charge de couple et/ou d'une consommation de carburant instantanée

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6709240B1 (en) * 2002-11-13 2004-03-23 Eaton Corporation Method and apparatus of detecting low flow/cavitation in a centrifugal pump
WO2009006927A1 (fr) 2007-07-11 2009-01-15 Siemens Aktiengesellschaft Procédé en vue d'éviter le fonctionnement à sec d'une pompe centrifuge, module de surveillance de pompe et système
US7539549B1 (en) * 1999-09-28 2009-05-26 Rockwell Automation Technologies, Inc. Motorized system integrated control and diagnostics using vibration, pressure, temperature, speed, and/or current analysis
US20100166570A1 (en) * 2008-12-29 2010-07-01 Little Giant Pump Company Method and apparatus for detecting the fluid condition in a pump

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7539549B1 (en) * 1999-09-28 2009-05-26 Rockwell Automation Technologies, Inc. Motorized system integrated control and diagnostics using vibration, pressure, temperature, speed, and/or current analysis
US6709240B1 (en) * 2002-11-13 2004-03-23 Eaton Corporation Method and apparatus of detecting low flow/cavitation in a centrifugal pump
WO2009006927A1 (fr) 2007-07-11 2009-01-15 Siemens Aktiengesellschaft Procédé en vue d'éviter le fonctionnement à sec d'une pompe centrifuge, module de surveillance de pompe et système
US20100166570A1 (en) * 2008-12-29 2010-07-01 Little Giant Pump Company Method and apparatus for detecting the fluid condition in a pump

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019034426A2 (fr) 2017-08-15 2019-02-21 KSB SE & Co. KGaA Procédé de protection contre la cavitation en cas de cyberattaques et unité pour mettre en oeuvre ce procédé
DE102017214203A1 (de) 2017-08-15 2019-02-21 KSB SE & Co. KGaA Verfahren zum Schutz vor Kavitation bei Cyberangriffen und Einheit zur Durchführung des Verfahrens
US11475129B2 (en) 2017-08-15 2022-10-18 KSB SE & Co. KGaA Method for the protection against cavitation in cyber attacks and unit for carrying out the method
WO2019096545A1 (fr) 2017-11-15 2019-05-23 KSB SE & Co. KGaA Procédé et dispositif de protection contre des cyberattaques de groupes motopompes
US11487262B2 (en) 2017-11-15 2022-11-01 KSB SE & Co. KGaA Method and apparatus for protecting pump units from cyber attacks
WO2021227221A1 (fr) * 2020-05-09 2021-11-18 蜂巢动力系统(江苏)有限公司 Procédé de protection contre la marche à sec pour pompe à eau électrique
EP4372221A1 (fr) * 2022-11-18 2024-05-22 Cattron North America, Inc. Détection de cavitation à l'aide d'une charge de couple et/ou d'une consommation de carburant instantanée

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