DE112011101269B4 - Phase shift control for an oscillating pump system - Google Patents

Abstract

The present invention discloses a pump system using a plurality of oscillating positive displacement pumps, the phase shifts of which are controlled by a phase shift controller. The phase shift control uses a virtual master pump within the phase shift control, which is used as a phase reference with respect to which the phase shifts of the individual pumps are calculated. The phase shift control sets the speed reference setpoint for the continuously variable drives of the individual pumps in such a way that a desired phase shift is obtained and maintained. By operating several oscillating pumps using the phase shift control, the pressure pulsation levels in the pump system can be significantly reduced. By using a virtual master pump, master / slave clocking is eliminated and the reliability and availability of the system are increased, since the operation of the phase control does not depend on the reliability of a real master pump, as is the case with state-of-the-art phase shift controls the case is.

Description

Technical area

This invention relates generally to pumps and, more particularly, to a variety of positive displacement reciprocating pumps for handling mineral slurries.

State of the art

In comparison to, for example, single-stage centrifugal pumps, oscillating displacement pumps are used for pumping a fluid with a relatively high back pressure. Other properties of these positive displacement pumps include high efficiency and accurate flow rates, but relatively low flow rates compared to centrifugal pumps. If the flow requirements of a typical application cannot be met with a single pump, multiple positive displacement pumps can be arranged in parallel so that their suction and / or discharge ports are connected to a single suction and / or discharge line. This means that the sum of the flows of the individual pumps can meet the requirements of the application in terms of total flow. The combination of the individual pumps and the interconnection of suction and discharge lines form a pump system.

In the case of oscillating pumps, a displacement element such as a piston or tappet performs a reciprocating movement in a cylinder liner, with the fluid being able to be pumped via the displacement. In a specific embodiment of an oscillating pump, the reciprocating movement of the displacement element is generated by a mechanism which converts the rotary movement of the pump drive into a reciprocating movement of the displacement element. Certain embodiments of this mechanism may include a crankshaft, eccentric shaft, camshaft, or cam disc mechanisms.

In the following description, only the embodiment of the crankshaft type is described, hereinafter referred to as a positive displacement pump with a crankshaft drive. 1 shows a schematic cross section of a single-acting 3-cylinder or triplex positive displacement pump with crankshaft drive. The displacement element may displace the pumped fluid directly or displace an intermediate fluid that displaces a flexible displacement element that displaces the pumped fluid such as an abrasive slurry. The invention relates to an embodiment of a positive displacement pump, but because the improvement is of particular interest to positive displacement slurry pumps described below, the embodiment employs an intermediate fluid and flexible displacement element, as specifically shown in FIG 1 shown.

A typical feature of a positive displacement pump with a crankshaft drive is the non-constant oscillation speed of the displacement element. Positive displacement pumps with crankshaft drive therefore inherently generate a non-constant current or a flow pulsation with each revolution of the crankshaft. 2 shows a typical flow pulsation that is generated during one crankshaft revolution or one pumping cycle of a single-acting triplex positive displacement pump. Depending on the hydraulic response of the connected system, these flow pulsations can lead to pressure pulsations in the pumped fluid, which can cause vibrations of the pipe system and of its support structure through which the fluid flows, and the pressure pulsations can create an asymmetrical load in the pipe system.

If more than one positive displacement pump with crankshaft drive is connected to a single suction and / or discharge inlet or outlet, an interaction between the flow pulsations generated by the individual pumps can occur. This interaction can cancel out or increase the total flow height and pressure pulsations in the pump system, which in turn depends on the hydraulic response of the connected system. Hydraulic resonances present in the pump system can also be excited by the flow pulsations generated by each individual pump. An important parameter that determines the total flow and pressure pulsation in a given pump system is the phase shift between the crankshafts of the individual pumps. Control of this phase shift can therefore be useful in controlling flow and pressure pulsation in a given pumping system using positive displacement crankshaft pumps.

This phase shift control, also referred to as pump synchronization, is described below and is shown in FIG 3 shown. Phase shift control requires pumps that are equipped with continuously variable drives (VSD) that can be used to set and maintain the phase shift between the pumps by adjusting the speed of the individual drives. In addition, the individual pumps and / or their drives are equipped with a phase sensor that determines the position of the pumping cycle of the individual Pump indicates, hereinafter referred to as the phase of the individual pump. This phase information is then used by a phase shift calculation unit to calculate the phase shifts between the individual pumps, which are then used by the phase shift control to set the speeds of the individual pumps so that the phase shift is adjusted or adjusted in the direction of the desired phase shift. is held at this.

In the known prior art, a pump in the pump system is designated as a guide pump. This master pump keeps track of the speed reference setpoint in the pump system without any adjustments related to phase shift control. The other pumps are designed as subordinate pumps that must follow the lead pump. The phase shift control calculates the phase difference between the master pump and each slave pump and generates a speed setpoint for each slave pump based on the phase shift between the master pump and each slave pump so that a constant and desired phase shift between the master pump and a slave pump is preserved and maintained.

1. 1. Der Systembetreiber muss vor dem Anlaufen des Pumpensystems entscheiden, welche Pumpe als Leitpumpe arbeiten soll, wonach die Phasenverschiebung der untergeordneten Pumpen in Bezug auf die ausgewählte Leitpumpe bestimmt wird. Dies kann zu komplexen Master/Slave- und Phasenverschiebungs-Vertaktungsabläufen führen, die auch von dem bestimmten System abhängig sein können.
2. 2. Die Phasenverschiebungssteuerung geht verloren, wenn die Leitpumpe einen Aussetzer hat oder abgeschaltet werden muss. Je nach der spezifischen Ausführungsform der Phasenverschiebungssteuerung kann es erforderlich sein, das gesamte Pumpensystem abzuschalten, weil die Master- und Slave-Initialisierung von einem Neustart weg eine Neuinitialisierung benötigen könnte. Die Zuverlässigkeit der Phasenverschiebungssteuerung für das gesamte Pumpensystem hängt somit von der Zuverlässigkeit einer einzigen Pumpe ab, die als Leitpumpe bestimmt ist.
3. 3. Wenn der Betrieb der Leitpumpe instabil ist, zum Beispiel durch eine Fehlfunktion von Ansaug- und/oder Abströmventilen, kann eine Drehzahlschwankung der Leitpumpe auftreten. Der resultierende instabile Betrieb der Leitpumpe führt zur Entstehung eines instabilen Betriebs in allen anderen Pumpen im Pumpensystem und somit zu einem instabilen Betrieb des gesamten Pumpensystems.

This approach has several shortcomings:

1. 1. Before starting up the pump system, the system operator must decide which pump is to work as the master pump, after which the phase shift of the subordinate pumps in relation to the selected master pump is determined. This can lead to complex master / slave and phase shift clocking processes, which can also be dependent on the particular system.
2. 2. Phase shift control is lost if the master pump fails or needs to be shut down. Depending on the specific embodiment of the phase shift control, it may be necessary to shut down the entire pump system, because the master and slave initialization may require reinitialization after a restart. The reliability of the phase shift control for the entire pump system thus depends on the reliability of a single pump, which is designated as the lead pump.
3. 3. If the operation of the lead pump is unstable, for example due to a malfunction of the suction and / or discharge valves, a speed fluctuation of the lead pump can occur. The resulting unstable operation of the lead pump leads to the development of unstable operation in all other pumps in the pump system and thus to unstable operation of the entire pump system.

These inadequacies are of particular concern in positive displacement pumps with crankshaft drives used in the mining and mineral processing industries where highly abrasive slurries are pumped. Applications in mining and the mineral processing industry require continuous operation of the pumping system without unexpected interruptions. In addition, in applications with high volume flows, which are also typical for mining and the mineral processing industry, the inadequacies of the known arrangements are even more significant.

Embodiments used and known in the prior art are normally limited to three or four pumps per pump system, for which the master / slave timing processes are relatively simple. In addition, the total throughput of the prior art pump systems with phase shift control is limited, so that the system can still work reliably because asymmetrical loads generated by the pressure pulsations are relatively low and may still be tolerable for some applications.

However, for high sludge applications in the mining and mineral processing industries, a significantly higher number of pumps may be used in a single pumping system. Known examples typically use up to 10 pumps in a single pump system, which makes master / slave timing very complex. The increased size of the pump systems used in mining and the mineral processing industry can lead to the asymmetrical loads generated by the pressure pulsations in the pump system and in the connected pipe network being of such magnitude that phase shift control is a basic requirement for reliable operation of the pump system is.

In addition, it should be noted that due to the abrasive properties of the pumped sludge, which lead to increased wear of pump components, the time between individual maintenance work on positive displacement sludge pumps can be relatively short compared to sludge-free applications. Whenever maintenance is required on the lead pump, a new lead pump needs to be determined, which might require shutdown of the pump system, what in turn has a strong influence on the availability of the entire pump system, in which continuous operation is preferred.

WO 2009/079 447 A1 discloses a synchronous torque balance control in a system that implements several pump systems that are operated at variable speeds and in which their speeds are set based on measured torque signals so that the various pumps can be operated at variable speeds Speed are operated and run together with a substantially synchronous torque. By synchronizing the torque, the flow of the different pumps is balanced, even if the different pumps have different hydraulic head curves. However, neither the phase information of the individual pump is used, nor is the individual phase information compared with a desired virtual reference phase. The speed of the individual pump is also not adapted on the basis of this phase difference comparison.

The EP 0 669 462 A1 shows a concrete pump with at least two pumping piston / cylinder assemblies that deliver cyclically into a line system, the piston / cylinder assemblies being driven by a drive assembly, characterized in that the drive assembly has a controllably adjustable drive characteristic in the ejection cycle of the piston and a manually operated input member on one Characteristic control input on the drive acts and / or a control signal, which appears on the output side of a subtraction unit, as a result of the comparison of a signal that is dependent on the pulsation amplitudes on a section of the line system and a specifiable target value signal, for regulating the pressure pulsations on the mentioned section to a desired value.

Summary of the invention

The present invention is directed to a solution to the described inadequacies of the phase shift control systems of prior art positive displacement crankshaft pumps. In the prior art systems, a real pump is used as the lead pump in a maser slave control scheme to control the phase shift between the lead pump and the slave pump. The disadvantages included the complex master / slave timing procedures, the reduced reliability of the pump system as it depends on the reliability of a single lead pump, and the reduced performance of the entire pump system in the event of unstable operation of the lead pump.

The present invention is concerned with a pump system using a plurality of oscillating positive displacement pumps, the phase shifts of which are controlled by a phase shift controller. The phase shift control uses a virtual master pump in the phase shift control, which is used as a phase reference and with respect to which the phase shifts of the individual pumps are calculated. The phase shift control sets the speed reference setpoint for the continuously variable drives of the individual pumps in such a way that a desired phase shift is obtained and maintained. By operating several oscillating pumps using the phase shift control, the pressure pulsation levels in the pump system can be significantly reduced. Using a virtual master pump eliminates the need for master / slave timing and increases the reliability and availability of the system, since the operation of the phase control does not depend on the reliability of a real master pump, as is the case with phase shift controls from the prior art Case is.

The virtual master pump generates a phase reference signal within the phase shift controller based on a reference speed setpoint for a single pump system, just as a real master pump would. All real pumps in the pump system function as subordinate pumps in the phase shift control. The phase of each individual pump is compared with the phase of the virtual master pump within the controller, which is then used as an input for the phase shift control. 4th Fig. 10 shows a control flow diagram for phase shift control with virtual master pump.

The use of a virtual lead pump can provide some operational improvements over the known prior art phase shift control systems for positive displacement pumps with crankshaft drives. The subordinate pumps are always related to the same virtual master pump, which means that no clocking is required. The virtual lead pump is considered to be always available because it does not require maintenance and is much more reliable than a real mechanical pump. In addition, the speed of the lead pump is always stable because it is not affected by the performance of a single lead pump, which is particularly useful when a positive displacement pump is used to pump abrasive slurries in the mining and mineral processing industries.

The invention is not limited to single-acting triplex positive displacement pumps, but rather can be used on all single and double-acting positive displacement pumps with one or more cylinders.

Figure list

• 1 einen schematischen Querschnitt einer einfachwirkenden Triplex-Verdrängerpumpe aus dem Stand der Technik darstellt, in der auch eine Ausführungsform gezeigt ist, bei der ein zwischengeschaltetes Fluid und ein zusätzliches flexibles Verdrängungselement verwendet werden;
• 2 eine Strömungspulsation einer einfachwirkenden Triplex-Verdrängerpumpe aus dem Stand der Technik zeigt;
• 3 ein dem Stand der Technik zugehöriges Steuerablaufdiagramm einer Phasensteuerung einer oszillierenden Pumpe mit einem Master/Slave-Steuerschema darstellt, bei dem eine reale Pumpe als Leitpumpe verwendet wird;
• 4 ein Steuerablaufdiagramm einer Phasensteuerung einer oszillierenden Pumpe mit einem Master/Slave-Steuerschema darstellt, bei dem eine virtuelle Leitpumpe gemäß der vorliegenden Erfindung verwendet wird.

Notwithstanding all other forms that may fall within the scope of the device set forth in the abstract, specific embodiments will now be described by way of example and with reference to the accompanying drawings, in which:

• 1 a schematic cross-section of a single-acting triplex positive displacement pump from the prior art, in which also an embodiment is shown in which an intermediate fluid and an additional flexible displacement element are used;
• 2 shows a flow pulsation of a single-acting triplex positive displacement pump from the prior art;
• 3 Fig. 3 is a prior art control flow diagram of phase control of an oscillating pump with a master / slave control scheme using a real pump as a lead pump;
• 4th Figure 12 is a control flow diagram of phase control of an oscillating pump with a master / slave control scheme using a virtual master pump in accordance with the present invention.

Detailed description of specific embodiments

The present invention comprises several embodiments for the individual parts of the phase shift control. For the sake of completeness, some embodiments are compiled:

Infinitely variable drive

1. 1. Elektrische Wechselstromantriebe
2. 2. Elektrische Gleichstromantriebe
3. 3. Dieselantriebe
4. 4. Hydraulische Antriebe

The invention is not limited to a specific embodiment of the continuously variable drive used; however, the following embodiments are mentioned in particular:

1. 1. Electric AC drives
2. 2. Electric DC drives
3. 3. Diesel drives
4. 4. Hydraulic drives

Phase sensor for the pumping cycle

1. 1. Die Sensorausführungsform kann eine absolute Phaseninformation über den Pumpzyklus erzeugen.
2. 2. Die Sensorausführungsform kann eine relative Phaseninformation über den Pumpzyklus erzeugen, die mit einer Nullpunktreferenz der Pumpzyklusphase kombiniert wird.
3. 3. Die Sensorausführungsform kann eine Phaseninformation über den Pumpzyklus auf der Grundlage der Winkelposition der Rotationshauptkomponente in der Pumpe erzeugen, die die Drehbewegung des Pumpenantriebs in eine hin- und hergehende Bewegung der Verdrängungselemente umwandelt, wie zum Beispiel einer Kurbelwelle.
4. 4. Die Sensorausführungsform kann eine Phaseninformation über den Pumpzyklus auf der Grundlage der linearen Position eines oder mehrerer Verdrängungselemente in der Pumpe erzeugen.
5. 5. Die Sensorausführungsform kann eine Phaseninformation über den Pumpzyklus auf der Grundlage der Winkelposition des stufenlos regelbaren Antriebs erzeugen, der direkt oder über eine Drehzahlreduktionsvorrichtung mit bekanntem Untersetzungsverhältnis an die Rotationshauptkomponente in der Pumpe angekoppelt sein kann.
6. 6. Die Sensorausführungsform kann eine Phaseninformation über den Pumpzyklus auf der Grundlage eines Einzelimpulses erzeugen, der an einer vorbestimmten Position des Pumpzyklus erzeugt wird.
7. 7. Die Sensorausführungsform kann eine Phaseninformation über den Pumpzyklus auf der Grundlage von mehreren Impulsen erzeugen, die an vorbestimmten Positionen des Pumpzyklus erzeugt werden.
8. 8. Die Sensorausführungsform kann eine Phaseninformation über den Pumpzyklus auf der Grundlage von mehreren Impulsen erzeugen, die an vorbestimmten Positionen des Pumpzyklus erzeugt werden, derart, dass die Anzahl von Impulsen pro Pumpzyklus gleich der Anzahl von Verdrängungselementen in der Pumpe ist.
9. 9. Die Sensorausführungsform kann aus einer beliebigen Kombination der wie vorstehend beschriebenen Sensorausführungsformen bestehen.

The invention is not restricted to a specific embodiment of the phase sensor used; however, the following embodiments are mentioned in particular:

1. 1. The sensor embodiment can generate absolute phase information about the pumping cycle.
2. 2. The sensor embodiment can generate relative phase information about the pumping cycle that is combined with a zero point reference of the pumping cycle phase.
3. 3. The sensor embodiment can generate phase information about the pumping cycle based on the angular position of the main rotational component in the pump, which converts the rotary motion of the pump drive to reciprocating motion of the displacement elements, such as a crankshaft.
4. 4. The sensor embodiment can generate phase information about the pumping cycle based on the linear position of one or more displacement elements in the pump.
5. 5. The sensor embodiment can generate phase information about the pumping cycle based on the angular position of the continuously variable drive, which can be coupled to the main rotational component in the pump directly or via a speed reduction device with a known reduction ratio.
6. 6. The sensor embodiment can generate phase information about the pumping cycle based on a single pulse generated at a predetermined position of the pumping cycle.
7. 7. The sensor embodiment can generate phase information about the pumping cycle based on multiple pulses generated at predetermined positions on the pumping cycle.
8. 8. The sensor embodiment can generate phase information about the pumping cycle based on multiple pulses generated at predetermined positions of the pumping cycle such that the number of pulses per pumping cycle is equal to the number of displacement elements in the pump.
9. 9. The sensor embodiment can consist of any combination of the sensor embodiments as described above.

Phase shift control

1. 1. Analoge elektronische Steuerschaltung
2. 2. Digitale elektronische Steuerschaltung auf der Grundlage der Halbleiterelektronik
3. 3. Programmierbare Steuerung unter Verwendung von Mikroprozessortechnologie
4. 4. Programmierbare Speichersteuerung
5. 5. Eingebetteter Mikrocontroller

The invention is not restricted to a specific embodiment of the phase shift control, but the following embodiments are mentioned in particular.

1. 1. Analog electronic control circuit
2. 2. Digital electronic control circuit based on semiconductor electronics
3. 3. Programmable control using microprocessor technology
4. 4. Programmable memory control
5. 5. Embedded microcontroller

Claims (14)

Phase shift control device used to control the individual speeds of multiple oscillating positive displacement pumps so that a desired phase shift is obtained and maintained between the pumping cycles of the individual pumps, phase sensor embodiments being included for generating phase information of the pumping cycles of the individual pumps thereby characterized in that the phase information of the individual pump cycles is compared with a virtual reference phase which is generated in the phase shift control device, which phase difference is used to set the speed setpoints for the individual continuously variable drives of the individual pumps. Phase shift control device according to Claim 1 , characterized in that the pump contains some type of mechanism to convert the rotary movement of the pump drive into a reciprocating movement of the displacement elements in the pump, such as, but not limited to, a crankshaft, eccentric shaft, camshaft or cam disk . Phase shift control device according to Claim 1 , characterized in that the continuously variable drive can be in any embodiment, such as limited to electrical AC or DC drives, diesel drives and hydraulic drives. Phase shift control device according to Claim 1 , characterized in that the sensor embodiment generates absolute phase information about the pumping cycle. Phase shift control device according to Claim 1 , characterized in that the sensor embodiment generates relative phase information about the pumping cycle which is combined with a zero point reference of the pumping cycle phase. Phase shift control device according to Claim 1 , characterized in that the sensor embodiment generates phase information about the pumping cycle based on the angular position of the main rotational component in the pump, which converts the rotational movement of the pump drive into a reciprocating movement of the displacement elements, such as a crankshaft. Phase shift control device according to Claim 1 , characterized in that the sensor embodiment generates phase information about the pumping cycle based on the linear position of one or more displacement elements in the pump. Phase shift control device according to Claim 1 , characterized in that the sensor embodiment generates phase information about the pumping cycle on the basis of the angular position of the continuously variable drive, which can be coupled to the main rotation component in the pump directly or via a speed reduction device. Phase shift control device according to Claim 1 , characterized in that the sensor embodiment generates phase information about the pumping cycle based on a single pulse generated at a predetermined position of the pumping cycle. Phase shift control device according to Claim 1 , characterized in that the sensor embodiment generates phase information about the pumping cycle based on a plurality of pulses generated at predetermined positions of the pumping cycle. Phase shift control device according to Claim 1 , characterized in that the sensor embodiment generates phase information about the pumping cycle based on a plurality of pulses generated at predetermined positions of the pumping cycle such that the number of pulses per pumping cycle is equal to the number of displacement elements in the pump. Phase shift control device according to Claim 1 , characterized in that the sensor embodiment consists of any combination of sensor embodiments as shown in FIG Claim 4 , 5 , 6th , 7th , 8th , 9 , 10 and 11 are described. A pump system using a plurality of oscillating positive displacement pumps having a phase shift control device as claimed in any one of the preceding claims. A method for controlling the individual speeds of a plurality of oscillating positive displacement pumps in such a way that a desired phase shift is obtained and maintained between the pumping cycles of the individual pumps, comprising the following steps: Generation of phase information of the pumping cycles of the individual pumps, Generating a virtual reference phase in a phase shift control device, Compare the phase information of the pumping cycles with the virtual reference phase, Determining the phase difference between the phase information and the virtual reference phase, and Setting the speed setpoints for the individual, infinitely variable drives of the individual pumps on the basis of the phase difference.

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