Centrifugal pump operation

Abstract

Examples include a method for controlling a hydraulic pumping system, the system including a centrifugal pump operating at a functional point. The method uses the parameters of the centrifugal pump at the functional point and the line-end characteristics of the centrifugal pump to determine an updated NPSH r value.

Description

Technical Field

[0001] This invention relates to a method for controlling a hydraulic pumping system. In particular, this invention relates to preventing cavitation in centrifugal pumps. Background Technology

[0002] A centrifugal pump is a pump that uses a motor to convert rotational kinetic energy into fluid kinetic energy. The fluid enters through the suction flange of the centrifugal pump and is accelerated by the multiple blades of the impeller.

[0003] Centrifugal pumps may experience cavitation during operation. Cavitation can involve two steps:

[0004] -In the first step, the fluid evaporates due to the decrease in fluid pressure, generating water vapor bubbles at the impeller eye.

[0005] - In the second step, due to the increase in fluid pressure causing the bubbles to condense, the steam bubbles inside the centrifugal pump core undergo an implosion.

[0006] Cavitation, especially the implosion of steam bubbles, can cause mechanical damage, noise, and vibration in centrifugal pumps, leading to permanent damage. In fact, cavitation shortens pump life and increases maintenance costs. Furthermore, when cavitation occurs, the pump motor's power at a given speed may decrease compared to the pump's rated operating speed.

[0007] Several solutions can be considered to protect centrifugal pumps from cavitation.

[0008] For example, one solution is to compare the pump's inlet pressure to a threshold and issue an alarm when the inlet pressure falls below the threshold. However, the threshold does not correspond to the actual inlet pressure that causes cavitation.

[0009] Another solution is to detect cavitation by monitoring motor power based on motor speed, and slowing down the pump's motor speed when a significant power drop is detected (i.e., cavitation is detected). However, this solution means that cavitation actually occurs before the motor speed is slowed down to dissolve the phenomenon, leading to pump damage.

[0010] Another solution is to use a net positive suction head (NPSH) at the function point of the centrifugal pump. a The net positive suction head (NPSH) is greater than the required net positive suction head (hereinafter referred to as "NPSH"). r NPSH r and NPSH a These all correspond to the pressure at the centrifugal pump's suction flange. NPSH r Typically calculated by the manufacturer, it is a pump characteristic, while NPSH a Calculated by the pump user and depends on the hydraulic system. NPSH rThis ensures that at the function point of the centrifugal pump, if NPSH a Value greater than NPSH r If cavitation occurs, it should not occur or damage the centrifugal pump.

[0011] However, during the lifespan of a centrifugal pump, as the pump's hydraulic parameters change over time, the NPSH provided by the manufacturer... r The curve is becoming increasingly unreliable, NPSH r The curve design depends on the hydraulic parameters. Therefore, in the long run, even in NPSH... a Larger than the NPSH provided by the manufacturer r In some cases, cavitation may occur, leading to irreparable damage. Summary of the Invention

[0012] Therefore, one object of this disclosure is to provide a method for controlling hydraulic pumping systems to avoid cavitation that can cause damage, particularly in the case of used centrifugal pumps.

[0013] Another objective is to allow for the detection of current or future cavitation in centrifugal pumps so that an alarm can be issued.

[0014] To achieve these objectives, this disclosure proposes to determine the appropriate NPSH for a centrifugal pump based on the evolution of hydraulic parameters of the centrifugal pump during its lifespan and the line-end characteristics of the centrifugal pump. r Value. Adapted to NPSH r The value refers to the NPSH value based on the evolution of hydraulic parameters of a centrifugal pump during its service life. r The updated value. Therefore, to prevent cavitation in the centrifugal pump at every moment of its service life, it is necessary to adapt to NPSH. r The value can be used to replace the NPSH calculated when the centrifugal pump is new. r value.

[0015] This disclosure describes a computer-implemented method for controlling a hydraulic pumping system, the system including a centrifugal pump operating at a function point, the method comprising:

[0016] - Estimate the suction pressure of the centrifugal pump, which represents the pressure at the inlet point of the centrifugal pump;

[0017] - Estimate the discharge pressure of the centrifugal pump, which represents the pressure at the outlet point of the centrifugal pump;

[0018] - Calculate the current head of the centrifugal pump based on the suction pressure and discharge pressure;

[0019] - The theoretical head is determined based on the values ​​of specific functional parameters related to the function point of the centrifugal pump in the system and the line-end characteristics of the centrifugal pump;

[0020] - Calculate the head difference between the current head and the theoretical head; and

[0021] -Based on head difference and line end characteristics, determine the appropriate net positive suction head requirement value aNPSH for the centrifugal pump at the function point. r .

[0022] This control method allows for the real-time determination of the centrifugal pump's adaptive NPSH parameters to match its hydraulic parameters throughout the pump's lifespan. r Value. Adapted to NPSH r The value allows pump users to prevent centrifugal pumps from suffering cavitation, or at least to predict cavitation during the life of the centrifugal pump.

[0023] Optionally, a specific functional parameter is one of the motor power or flow rate of the centrifugal pump.

[0024] These parameters allow for the use of readily available centrifugal pump data in hydraulic pumping systems to implement control methods. In practice, flow rate can be measured by a flow meter, motor power can be estimated by a variable speed drive, or it can be estimated based on measurements from an energy meter.

[0025] Optionally, the line-end characteristics include multiple representations, each related to a specific speed of the centrifugal pump, and each representation relating the value of a first corresponding reference parameter to the value of a second corresponding reference parameter, the first corresponding reference parameter being different from the second corresponding reference parameter.

[0026] This representation allows for the determination of the evolution of the hydraulic parameters of the centrifugal pump and the evolution of the NPSHr value between the new centrifugal pump state and the centrifugal pump state when the method is implemented.

[0027] Optionally, one of the first or second reference parameters corresponds to a specific functional parameter.

[0028] This reference parameter, corresponding to specific functional parameters, allows for the direct determination of the evolution of hydraulic parameters between new and existing centrifugal pumps during the execution of the method, without the need for conversion.

[0029] Optionally, the first or second reference parameter corresponds to the motor power of the centrifugal pump, the flow rate of the centrifugal pump, and the required net positive suction head (NPSH) of the centrifugal pump. r Or one of the pressure heads of a centrifugal pump.

[0030] These first and second reference parameters allow for the determination of:

[0031] - Based on the head difference of the centrifugal pump's flow rate or motor power,

[0032] -NPSH based on centrifugal pump head, flow rate, or motor power r value.

[0033] Optionally, the specific functional parameter is the functional flow rate of the centrifugal pump, and multiple representations include a head representation that correlates the flow rate value with the head value, and a representation that correlates the flow rate value with the NPSH value. r Value-related NPSH r express,

[0034] Determining the theoretical head includes selecting the head value represented by the functional flow rate of the centrifugal pump;

[0035] And among them, aNPSH was determined r Values ​​include NPSH based on the functional flow rate selection of the centrifugal pump. r NPSH r value.

[0036] This implementation allows for the determination of the appropriate NPSH based on the centrifugal pump's flow rate at the function point. r value.

[0037] Optionally, a specific functional parameter is the centrifugal pump's functional motor power, with multiple representations including a head representation that correlates the motor power value with the head value and a representation that correlates the motor power value with the NPSH value. r Value-related NPSH r express,

[0038] The determination of the theoretical head includes the head value represented by the head selected based on the functional motor power of the centrifugal pump; and

[0039] Among them, aNPSH was determined r Values ​​include NPSH-based selection of function motor power for centrifugal pumps. r NPSH r value.

[0040] This implementation allows for determining the appropriate NPSH based on the centrifugal pump's motor power at the function point. r value.

[0041] Optionally, aNPSH r The value is determined by selecting the NPSH. r It is obtained by adding the value and the pressure head difference.

[0042] This addition allows for direct calculation based on the head difference between the new centrifugal pump and the centrifugal pump during method execution, as well as the NPSH of the new pump at the function point. r To obtain adaptation to NPSH r value.

[0043] Optionally, the specific functional parameter is the functional flow rate of the centrifugal pump, and the method further includes:

[0044] - Obtain the functional flow rate of the centrifugal pump through a flow meter.

[0045] This acquisition allows for the determination of specific functional parameters based on sensor measurements.

[0046] Optionally, the method further includes:

[0047] - Use a centrifugal pump to pump fluids with a density higher than that of water.

[0048] This pumping method allows the centrifugal pump to prevent cavitation in hydraulic systems, which can more easily cause pump damage, such as in fluid systems used for fish and shellfish aquaculture.

[0049] Optionally, the method further includes:

[0050] - Use a centrifugal pump to pump fluids containing solids.

[0051] This pumping method allows the centrifugal pump to prevent cavitation in hydraulic systems, which can more easily cause pump damage, such as in fluid systems used in water treatment plants.

[0052] Optionally, the method further includes:

[0053] - Determine the available net positive inhalation head value based on inhalation pressure; and

[0054] -When the net positive suction head (NPSH) is available a Value and aNPSH r When the difference between the values ​​is lower than a predetermined threshold, a cavitation alarm is triggered.

[0055] This method allows for the monitoring of impending cavitation and in NPSH a Value close to adaptive NPSH r An alarm will be issued when the value is reached.

[0056] Optionally, according to NPSH a Value and aNPSH r The difference between values ​​indicates that cavitation alarms include multiple levels of alarms.

[0057] This method allows for multiple types of alerts depending on the severity of the situation.

[0058] Optionally, the identification number is associated with a centrifugal pump, and the method further includes:

[0059] - Store the aNPSHr along with the centrifugal pump's identification number in the memory of the data processing device.

[0060] This method can collect statistical data, such as the NPSH of hydraulic centrifugal pump sets. r Statistical data.

[0061] This disclosure also describes a computer-readable storage medium including instructions that, when executed by a processor, cause the processor to perform any of the methods described herein. Such a processor may, for example, be a processor of a hydraulic pumping system controller.

[0062] This disclosure also describes a data device comprising a processor adapted to control a hydraulic pumping system according to the control method described above. Attached Figure Description

[0063] Figure 1 An example of a hydraulic pumping system is shown.

[0064] Figure 2 An example method is described.

[0065] Figure 3 An example including the represented line end features is shown.

[0066] Figure 4 Another example method is shown.

[0067] Figure 5 Another example method is shown.

[0068] Figure 6 Another example method is shown.

[0069] Figure 7 Additional example methods are shown. Detailed Implementation

[0070] This disclosure applies to control methods for hydraulic pumping systems. A hydraulic pumping system is a system that uses a centrifugal pump to pump fluid from one fluid reservoir to another. For example, a hydraulic pumping system could be a water treatment plant, an oil pumping station, a drinking water distribution system, or a desalination system that pumps used water. Examples of hydraulic pumping systems are as follows... Figure 1 As shown. Figure 1 The hydraulic pumping system 1 includes a first fluid reservoir 3 from which fluid can be pumped by a centrifugal pump 2. The fluid can be water, used water, brine, oil, or other fluids. For example, the fluid can have a higher density than water. The fluid can also include solids.

[0071] The hydraulic pumping system 1 may include a second fluid reservoir 4 to which fluid is pumped. Figure 1 In the example shown, fluid is pumped from the first reservoir 3 to the second reservoir 4 by centrifugal pump 2. In some examples, the pumping operation is reversible. Therefore, fluid from the second fluid reservoir 4 can be pumped back to the first reservoir 3 by centrifugal pump 2. Figure 1As shown, the bottom of the second reservoir 4 is positioned above the bottom of the first reservoir 3 due to gravity. Therefore, when fluid is pumped from the first reservoir 3 to the second reservoir 4, the centrifugal pump 2 is in suction mode, and when fluid is pumped from the second reservoir 4 to the first reservoir 3, the centrifugal pump is in filling mode.

[0072] The hydraulic pumping system 1 also includes a discharge pressure sensor (not shown) for measuring the discharge pressure Pd corresponding to the fluid pressure at the outlet of the centrifugal pump 2. The hydraulic pumping system 1 may also include a suction pressure sensor (not shown) for measuring the suction pressure Ps corresponding to the fluid pressure at the inlet of the centrifugal pump 2. The pressures described in this disclosure can be expressed in meters of water column (mH2O), where one meter of water column corresponds to 10... 5 Pascal.

[0073] The hydraulic pumping system may include a flow meter for measuring the flow rate of the centrifugal pump 2. The flow rate can be expressed in cubic meters per hour (m³ / s). 3 / h) is used to represent it.

[0074] The hydraulic pumping system 1 may include a variable speed drive (not shown) for controlling the motor of the centrifugal pump 2. The variable speed drive should be understood as an electronic, virtual, or software-implemented control unit for the motor of the centrifugal pump 2. The variable speed drive can estimate the motor power of the centrifugal pump 2. Motor power can be expressed in watts (W). For example, the variable speed drive can apply a defined electrical command to the motor of the centrifugal pump 2, such as to achieve a defined speed of the motor. The variable speed drive can also measure the motor's response to the electrical command. The variable speed drive can then estimate the motor power based on the defined electrical command and the motor's response.

[0075] The hydraulic pumping system 1 may include an energy meter (not shown) for measuring the energy consumption of the centrifugal pump 2. The motor power of the centrifugal pump 2 may be estimated based on the measurement of the energy consumption of the centrifugal pump 2.

[0076] The hydraulic pumping system 1 may also include a data processing device 5, which includes a processor PROC configured to operate according to any of the methods described herein. The processor PROC may include electronic circuitry for calculations managed by an operating system. The data processing device 5 may include a non-transitory machine-readable or computer-readable storage medium, such as a memory or storage unit MEM, whereby the non-transitory machine-readable storage medium is encoded with instructions executable by a processor, such as the processor PROC, including instructions that operate the processor PROC to execute according to any of the example methods described herein. Computer-readable storage according to this disclosure can be any electronic, magnetic, optical, or other physical storage device storing executable instructions. Computer-readable storage can be, for example, random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), storage drives, and optical discs. As described herein, computer-readable storage can be encoded with executable instructions according to any of the methods described herein. Memory or memory may include any electronic, magnetic, optical, or other physical storage device storing executable instructions as described herein.

[0077] During the operation phase of the hydraulic pumping system 1, i.e., when the centrifugal pump 2 pumps fluid from one reservoir to another, the centrifugal pump 2 operates at its function point. The function point of the centrifugal pump 2 can be related to its functional parameters. In other words, functional parameters characterize the centrifugal pump 2 at a specific function point. For example, the functional parameters associated with the function point of the centrifugal pump 2 during operation could be the motor power, expressed in watts (W), or the pump capacity, expressed in cubic meters per hour (m³ / h). 3 The flow rate is expressed as / h). Each functional parameter can be correlated with the functional speed ω of centrifugal pump 2, which can be expressed in radians per second (rd / s). f Related.

[0078] Figure 2 An example of a method 100 for controlling a hydraulic pumping system is shown, which can be implemented in an example of a hydraulic pumping system 1. The method 100 and other methods presented herein can be computer-implemented and can be implemented by a data processing device 5.

[0079] The method proposed in this paper for controlling a hydraulic pumping system can be implemented in real time during centrifugal pump operation. In some examples, the centrifugal pump 2 is in suction mode during method execution, i.e., the centrifugal pump 2 pumps fluid from the first reservoir 3 to the second reservoir 4 against gravity. In some examples, the method described herein can be implemented when the centrifugal pump 2 is in filling mode, i.e., pumping in the same direction as gravity.

[0080] Method 100:

[0081] refer to Figure 2Method 100 includes block 110 for estimating the suction pressure Ps of centrifugal pump 2. The suction pressure Ps corresponds to the fluid pressure at the inlet point of centrifugal pump 2. The inlet point of centrifugal pump 2 may correspond to the suction flange of centrifugal pump 2. Therefore, the suction pressure Ps may correspond to the pressure at the inlet point of the suction flange of centrifugal pump 2. For example, the suction pressure Ps may be estimated based on measurements from a suction pressure sensor, or it may be estimated based on characteristics of the hydraulic pumping system 1. For example, the suction pressure Ps may be estimated based on the pressure P at the top of the first reservoir 3 (which in most cases corresponds to atmospheric pressure), the gravitational equivalent value g (more generally referred to as the g-force value), the fluid density ρ, and the height h difference between the distance along the vertical axis between the centrifugal pump 2 and the bottom of the first reservoir 3 in the gravitational direction.

[0082] As shown in block 120, method 100 includes estimating the discharge pressure Pd of centrifugal pump 2. The discharge pressure Pd corresponds to the fluid pressure at the outlet point of centrifugal pump 2. In other words, the discharge pressure Pd corresponds to the outlet pressure of centrifugal pump 2. For example, the discharge pressure Pd can be estimated based on measurements from a discharge pressure sensor.

[0083] As shown in box 130, method 100 includes calculating the current head HMT of centrifugal pump 2. p Current pressure head HMT p This refers to the pressure provided by centrifugal pump 2 at its functional point.

[0084] Current pressure head HMT p The calculation is based on the intake pressure Ps and the discharge pressure Pd. Current head HMT p This can represent the difference between the discharge pressure Pd and the suction pressure Ps at the function point of centrifugal pump 2. Therefore, the current head HMT p This can correspond to the pressure difference between the inlet and outlet of centrifugal pump 2 at its functional point. Current head HMT p This can be used to represent the current state of the hydraulic parameters of centrifugal pump 2. Current HMT p It can be contained between 0.5 and 200 mH2O.

[0085] As shown in box 140, method 100 includes determining the theoretical head HMT of centrifugal pump 2. th The theoretical head is determined based on the specific functional parameter fp related to the functional point of the centrifugal pump 2 in the hydraulic pumping system 1 and the line-end characteristics of the centrifugal pump 2.

[0086] Theoretical pressure head HMT th This refers to the theoretical pressure provided by centrifugal pump 2 during the execution of this method, for the function point corresponding to the function point of centrifugal pump 2, when centrifugal pump 2 is relatively new (online end, meaning the end of the production line for new pumps). In other words, the theoretical head HMT.th and the current pressure head HMT p They may have significantly the same value at the beginning of a centrifugal pump's life. Theoretical head (HMT) th It can be contained between 0.5 and 200 mH2O.

[0087] The specific functional parameter fp associated with the function point of centrifugal pump 2 refers to the functional parameter as defined above that can be used in hydraulic pumping system 1. For example, when hydraulic pumping system 1 includes a flow meter, the functional parameter available for the function point and characterizing centrifugal pump 2 could be the flow rate of centrifugal pump 2. The flow rate of centrifugal pump 2 can include 0 and 600 m³ / h. 3 Between / h. Another example functional parameter available in the hydraulic pumping system 1 could be the motor power of the centrifugal pump 2 when the centrifugal pump 2 is controlled by a variable speed drive or / and when the hydraulic pumping system 1 includes an energy meter. As mentioned above, the motor power can be estimated by the variable speed drive and can be estimated based on the energy meter's measurement. The motor power of the centrifugal pump 2 can be between 3 and 1000 kW. For the function point of the centrifugal pump 2, a specific functional parameter fp can be related to the functional speed ω of the centrifugal pump 2. f Related. The functional speed ω of centrifugal pump 2. f It can be between 60 and 360rd / s.

[0088] Line-end characteristics refer to several parameters associated with centrifugal pump 2 at the line end, i.e., when centrifugal pump 2 is relatively new. For example, line-end characteristics can be provided by the manufacturer of centrifugal pump 2, or they can be calculated by the distributor or pump user on a test bench.

[0089] For example, line end characteristics may include a specific speed ω of centrifugal pump 2. s The related multiple representations R. The specific speed ω of centrifugal pump 2. s The value can be between 60 and 360 rd / s. R can be, for example, a curve, table, or list. Each representation R can correlate the value of a first corresponding reference parameter rp1 with the value of a second corresponding reference parameter rp2, the first being different from the second. The first and second corresponding reference parameters rp1 and rp2 can correspond to physical quantities, particularly the hydraulic parameters of the centrifugal pump 2. For example, at least one of the first or second reference parameters rp1 in the representation R can correspond to a specific functional parameter fp. For example, the first and / or second corresponding reference parameters rp1 and rp2 can correspond to the motor power of the centrifugal pump 2, the flow rate of the centrifugal pump 2, the NPSH of the centrifugal pump 2, etc. r Or one of the pressure heads HMT of centrifugal pump 2.

[0090] Examples of two representations of R are as follows Figure 3As shown. The line-end characteristics are represented by box EOL, including boxes R1 and R2. Box R1 shows the specific speed ω of centrifugal pump 2. s NPSH r The curve shows the value as a function of motor power. Box R2 shows the value at a specific speed ω of centrifugal pump 2. s The table below shows the head (HMT) values ​​related to the flow rate. It should be noted that... Figure 3 No exhaustive examples of line end characteristics are shown, and the box EOL may include, for example, those corresponding to other specific velocities ω. s The other boxes (R3, R4, ..., Rn).

[0091] For example, for a specific speed ω of a centrifugal pump s The wire ends may include:

[0092] - The head / flow rate is expressed as R, relating the flow rate value to the head HMT value of a relatively new centrifugal pump 2. H / f ,

[0093] - Compare the flow rate value with the NPSH of a fairly new centrifugal pump 2. r Value-related NPSH r / Flow rate representation R NPSHr / f ,

[0094] - The head / power ratio is expressed as a correlation between the flow rate value and the motor power value of a relatively new centrifugal pump 2. H / P ,

[0095] - Compare the motor power value with that of a fairly new centrifugal pump 2 NPSH r Value-related NPSH r / Power representation R NPSHr / P ,

[0096] - The flow rate / power ratio is expressed as R, relating the flow rate value to the motor power value of a relatively new centrifugal pump 2. f / P .

[0097] It should be understood that the specific functional parameter fp characterizing the functional point of centrifugal pump 2 can be used to find the head HMT associated with the functional point of centrifugal pump 2 in the line-end characteristics, such head HMT corresponding to the theoretical head HMT. th .

[0098] It should be noted that if a specific function parameter fp does not correspond to either the first reference parameter rp1 or the second reference parameter rp2 related to the head value HMT of centrifugal pump 2 in the line-end characteristics, then the specific function parameter fp can be converted into another function parameter related to the head value HMT of centrifugal pump 2 in the line-end characteristics. For example, if the specific function parameter fp is flow rate, and the line-end characteristics include head / power representation R... H / Pand flow / power representation R f / P The flow rate can then be expressed as flow rate / power R. f / P Converted to motor power, expressed as R based on head / power. H / P Determine the theoretical pressure head (HMT) th .

[0099] It should also be noted that if a specific function parameter fp is different from a specific velocity ω representing R, s Functional speed ω f If related, then all or part of each representation R can be converted into the functional velocity ω. f For example, the flow rate can be proportional to the speed ω of the centrifugal pump 2, the head HMT, and NPSH. r The speed of centrifugal pump 2 can be proportional to the square of the speed ω, and the motor power can be proportional to the cube of the speed ω of centrifugal pump 2.

[0100] As shown in box 150, method 100 includes calculating the current pressure head HMT. p and theoretical pressure head HMT th pressure head difference between As described above, given that centrifugal pump 2 is relatively new during the execution of this method, the head difference... It can be smaller than the theoretical pressure head HMT th 0.1%. For example, for a fairly new centrifugal pump 2, the head difference... It can be between 0 and 0.2 mH2O. Therefore, the pressure head difference... This can correspond to the evolution of the hydraulic parameters of centrifugal pump 2 from new centrifugal pump 2 to centrifugal pump 2 during the execution of the method.

[0101] As shown in box 160, method 100 includes determining a net positive inhalation head (NPSH) requirement value or aNPSH for the function point. r value.

[0102] Adaptation to NPSH r The value refers to the NPSH value based on the evolution of hydraulic parameters of centrifugal pump 2 during its service life. r The updated value.

[0103] According to the pressure head difference Determining aNPSH based on line terminal characteristics r value.

[0104] Therefore, method 100 allows for NPSH adapted to the hydraulic parameters of the centrifugal pump 2 during its lifespan. r The updated value.

[0105] Method 200:

[0106] Figure 4Example method 200 is shown below. Method 200 includes... Figure 2 The boxes 110-160 described in the text are the same as the boxes 110-160.

[0107] In example method 200, the hydraulic pumping system 1 includes a flow meter, and a specific functional parameter fp is the functional flow rate of the centrifugal pump. The functional flow rate refers to the flow rate of the centrifugal pump 2 at its functional point. Method 200 includes block 221 for obtaining the functional flow rate of the centrifugal pump 2 via the flow meter, and the specific functional parameter corresponds to the functional flow rate obtained via the flow meter. Block 221 can be used to calculate the theoretical head HMT. th Execute at any time before box 140.

[0108] Method 300:

[0109] Figure 5 Example method 300 is shown below. Method 300 includes... Figure 2 and 4 Blocks 110-160 and 221 described herein are identical to those in the diagram. In this embodiment, the line-end characteristics include a plurality of representations R. The plurality of representations R includes a head / flow representation R that correlates the flow rate value with the head HMT value. H / f and the flow value with NPSH r Value-related NPSH r / Flow rate representation R NPSHr / f .

[0110] In example method 300, the theoretical pressure head HMT is determined. th Box 140 includes sub-box 341: Selecting head / flow rate representation R based on the functional flow rate of centrifugal pump 2 obtained in box 221. H / f The head value (HMT). For example, the selected head (HMT) value could be a head / flow rate representation (R) associated with the same or closest flow rate value as the functional flow rate value. H / f The pressure head value HMT.

[0111] Functional speed ω related to functional flow f Unlike the head / flow rate representation R H / f The relevant specific velocity ω s In the case of selecting head / flow rate R H / f Before the head value, head / flow rate represents R. H / f All or part of it can be converted into functional velocity ω f As mentioned above, the flow rate can be considered proportional to the velocity ω of the centrifugal pump 2, and the head HMT can be considered proportional to the square of the velocity ω.

[0112] In the head / flow rate representation R H / fThe selected pressure head HMT in the data may correspond to the theoretical pressure head HMT. th .

[0113] In example method 300, aNPSH is determined. r Box 160 for the value includes sub-box 361: NPSH based on the functional flow rate of the centrifugal pump. r / Flow rate representation R NPSHr / f NPSH r Value. For example, the selected NPSH r The value can be an NPSH value that is the same as or closest to the function flow value. r / Flow rate representation R NPSHr / f NPSH r value.

[0114] Functional speed ω related to functional flow f Unlike NPSH r / Flow rate representation R NPSHr / f The relevant specific velocity ω s In the case of selecting NPSH r / Flow rate representation R NPSHr / f NPSH in r Before the value, NPSH can be used r / Flow rate representation R NPSHr / f All or part of the function speed ω is converted into the function speed ω f As mentioned above, the flow rate can be considered proportional to the speed ω of centrifugal pump 2, and the NPSH can be considered... r It is proportional to the square of the velocity ω.

[0115] Method 400:

[0116] Figure 6 Another example method 400 is shown, which is an embodiment of method 100 according to this disclosure. Method 400 includes... Figure 2 The boxes 110-160 described herein are identical to those in the previous section. In this embodiment, the specific function parameter fp is the function motor power of the centrifugal pump 2. The function motor power refers to the motor power of the centrifugal pump 2 at its function point. The function motor power can be obtained by reading the motor power of the centrifugal pump 2 at its function point. Also in this embodiment, the line-end characteristics include multiple representations R. The multiple representations R include a head / power representation R that correlates the motor power value with the head HMT value. H / P And compare the motor power value with NPSH r Value-related NPSH r / Power representation R NPSHr / P .

[0117] In example method 400, the theoretical pressure head HMT is determined.th Box 140 includes sub-box 441: Functional motor power selection based on centrifugal pump 2, head / power representation R H / P The head value HMT. For example, the selected head HMT value could be expressed as head / power R. H / P The pressure head value HMT is related to the motor power value that is the same as or closest to the functional motor power value.

[0118] The functional speed ω related to the power of the functional motor f Unlike the head / power representation R H / P The relevant specific velocity ω s In the case of selecting head / power representation R H / P Before the head value, the head / power representation is R. H / P All or part of it can be converted into functional velocity ω f As mentioned above, the motor power can be considered to be proportional to the cube of the velocity ω of the centrifugal pump 2, and the head HMT can be considered to be proportional to the square of the velocity ω.

[0119] In the pressure head / power representation R H / P The selected pressure head HMT can correspond to the theoretical pressure head HMT. th .

[0120] In example method 400, determine NPSH r Box 160 of the value includes sub-box 461: Functional motor power selection based on centrifugal pump NPSH r / Power representation R NPSHr / P NPSH r Value. For example, the selected NPSH r The value can be the NPSH value, which is the same as or closest to the functional motor power value. r / Power representation R NPSHr / P NPSH r value.

[0121] The functional speed ω related to the power of the functional motor f Unlike NPSH r / Power representation R NPSHR / rp The relevant specific velocity ω s In the case of selecting NPSH r / Power representation R NPSHR / rp NPSH in r Before the value, NPSH can be used r / Power representation R NPSHR / rp All or part of the function speed ω is converted into the function speed ω f As mentioned above, the motor power can be considered to be proportional to the cube of the speed ω of the centrifugal pump 2, and the NPSH can be considered...r It is proportional to the square of the velocity.

[0122] In methods 300 and 400, aNPSH r The value can be represented by R by associating the value of one of the reference parameters (flow rate or motor power, respectively, in methods 300 and 400). NPSHR / rp Selected NPSH r Value and NPSH r Value and pressure head difference The result is obtained by adding them together.

[0123] Method 500:

[0124] According to yet another example method 500 of this disclosure, in Figure 7 As shown in the diagram. Method 500 includes... Figure 2 The boxes 110-160 described herein are identical to those in the diagram. In fact, method 500 can be an embodiment of any of the methods 100 to 400 described above.

[0125] Example method 500 includes box 570: Determining the available net positive inhalation head (NPSH) based on inhalation pressure Ps a NPSH a The value refers to the pressure available at the suction flange of centrifugal pump 2 for the functional point. For example, the NPSH can be obtained based on the suction pressure Ps and the evaporation pressure of the fluid. a value.

[0126] like Figure 7 As shown, method 500 also includes block 580: when NPSH a Value and aNPSH r A cavitation alarm is triggered when the difference between the values ​​is below a predetermined threshold. As mentioned above, when NPSH a Value lower than aNPSH r When the value is specified, cavitation occurs. Therefore, box 280 allows for the prevention or warning of cavitation to the pump user. For example, the threshold may correspond to 0.5 mH2O or may include values ​​between 0.2 and 1 mH2O.

[0127] In another embodiment of method 500, the cavitation alarm includes multiple alarm levels, depending on the NPSH. a Value and aNPSH r The difference between values. For example, when NPSH a Value and aNPSH r A warning alarm may be triggered when the difference between values ​​is less than 0.5 mH2O. For example, when NPSH a Value and aNPSH rA warning alert may be triggered when the difference between values ​​is clearly zero. For example, when NPSH... a Value and aNPSH r A difference between values ​​less than -0.1 mH2O may trigger a fault alarm. For example, in the event of an alarm and / or fault alarm, a specific speed ω of centrifugal pump 2... f It can be reduced.

[0128] In one embodiment, each example method given herein may include pumping a fluid with a density higher than that of water and / or containing solids using a centrifugal pump 2. For example, the density of the pumped fluid may be 1 to 1.2 times the density of water. Such pumping, for example, allows for the prevention of cavitation in centrifugal pumps on hydraulic pumping systems used in water treatment plants for treating spent water or for brine used in fish and shellfish farming.

[0129] In one embodiment, the centrifugal pump 2 is associated with an identification number ID. In this embodiment, each example method described herein may include aNPSH r The value, along with the identification number (ID) of centrifugal pump 2, is stored in the memory of the data processing device. (This is followed by a seemingly unrelated sentence about aNPSH.) r Storing the value along with the identification number ID allows for the establishment of NPSH between different centrifugal pumps. r Statistical data on value evolution. For example, this can be based on the NPSH of a centrifugal pump over a defined lifespan. r Values ​​establish average NPSH r The centrifugal pumps are manufactured on the same production line. It's possible to compare the average NPSH of centrifugal pumps manufactured on different production lines. r This is to identify problems on a specific production line. The average NPSH on the production line... r The value can also be used to study the NPSH on this production line. r Value below average NPSH r Centrifugal pump.

Claims

1. A computer-implemented method for controlling a hydraulic pumping system (1), the system (1) including a centrifugal pump (2) operating at a function point, the method comprising: - Estimate the suction pressure (Ps) of centrifugal pump (2) (110), which represents the pressure at the inlet point of centrifugal pump (2); - Estimate the discharge pressure (Pd) of centrifugal pump (2) (120), which represents the pressure at the outlet point of centrifugal pump (2); - Based on inhalation pressure (Ps) and exhaust pressure (P) d ) Calculate the current head (HMT) of centrifugal pump (2) (130) p ); - The theoretical head (HMT) of centrifugal pump (2) is determined based on the value of a specific function parameter (fp) related to the function point of centrifugal pump (2) in system (1) and the line-end characteristics of centrifugal pump (2). th ); - Calculate (150) the current pressure head (HMT) p ) and theoretical pressure head (HMT) th The pressure head difference between () );as well as - Based on pressure head difference ( ) and line end characteristics, to determine the appropriate net positive suction head requirement value aNPSH for the function point of the centrifugal pump (2) (160). r value, Among them, real-time determination and use of aNPSH r The value is used instead of the required net positive suction head (NPSH) value provided by the manufacturer. r Values ​​are used to control the hydraulic pumping system, which includes a centrifugal pump operating at a function point.

2. The method according to claim 1, wherein, The specific functional parameter (fp) is one of the motor power of the centrifugal pump (2) or the flow rate of the centrifugal pump (2).

3. The method according to claim 1, wherein, The line end characteristics include multiple representations (R), each representing a specific speed (ω) of the centrifugal pump (2). s Each representation (R) correlates the value of a first corresponding reference parameter (rp1) with the value of a second corresponding reference parameter (rp2), the first corresponding reference parameter being different from the second corresponding reference parameter.

4. The method according to claim 3, wherein, One of the first corresponding reference parameter or the second corresponding reference parameter corresponds to a specific functional parameter.

5. The method according to claim 3, wherein, The first corresponding reference parameter or the second corresponding reference parameter corresponds to the motor power of the centrifugal pump (2), the flow rate of the centrifugal pump (2), and the required net positive suction head (NPSH) value of the centrifugal pump (2). r One of the values ​​of the head (HMT) of the centrifugal pump (2).

6. The method according to claim 3, wherein, The specific functional parameter (fp) is the functional flow rate of the centrifugal pump (2), and the plurality of representations (R) include a head / flow representation (R) that correlates the flow rate value with the head value (HMT). H / f ) and compare the flow value with NPSH r Value-related NPSH r / Flow representation (R) NPSHr / f ), Among them, the theoretical pressure head (HMT) of (140) was determined. th This includes centrifugal pump-based functional flow selection (341) head / flow rate representation (R) H / f The head value (HMT); and Among them, (160)aNPSH was determined. r Values ​​include the functional flow rate selection based on the centrifugal pump (161) NPSH r / Flow representation (R) NPSHr / f ) of NPSH r value.

7. The method according to claim 3, wherein, The specific functional parameter is the functional motor power of the centrifugal pump (2), and the plurality of representations (R) include a head / power representation (R) that correlates the motor power value with the head value (HMT). H / P ) and compare the motor power value with NPSH r Value-related NPSH r / Power representation (R) NPSHr / P ), Among them, the theoretical pressure head (HMT) of (140) was determined. th This includes a centrifugal pump (2) based on the function of motor power selection (141) head / power representation (R). H / P The head value (HMT); and Among them, (160)aNPSH was determined. r Values ​​include the function motor power selection (161) NPSH based on the centrifugal pump (2). r / Power representation (R) NPSHr / P ) of NPSH r value.

8. The method according to claim 1, wherein, The aNPSH r The value is obtained by passing NPSH r Value and pressure head difference ( It is obtained by adding them together.

9. The method according to claim 1, wherein, The specific functional parameter (fp) is the functional flow rate of the centrifugal pump (2), and the method further includes: - Obtain the functional flow rate of the centrifugal pump (2) through a flow meter.

10. The method according to claim 1, wherein, The method also includes: - Use a centrifugal pump (2) to pump fluids with a density higher than that of water, and / or - Use a centrifugal pump (2) to pump fluids containing solids.

11. The method according to claim 1, wherein, The method also includes: - Determine the available net positive inhalation head (NPSH) based on the inhalation pressure (Ps). a Value; and - When NPSH a Value and aNPSH r When the difference between the values ​​is lower than a predetermined threshold, a (280) cavitation alarm is triggered.

12. The method according to claim 11, wherein, The cavitation alarm includes those dependent on NPSH. a Value and aNPSH r Multiple levels of alerts for the differences between values.

13. The method according to claim 1, wherein, The identification number (ID) is associated with the centrifugal pump (2), and the method further includes: - will aNPSH r The value, along with the identification number (ID) of the centrifugal pump (2), is stored in the memory of the data processing device (5).

14. A computer-readable storage medium comprising instructions that, when executed by a processor (PROC), cause the processor to perform the method according to any one of claims 1-13.

15. A data processing device (5) comprising a processor adapted to control a hydraulic pumping system (1), the processor performing the method according to any one of claims 1-13.

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