APPARATUS AND METHOD FOR CONTROLLING A PUMP SYSTEM

• US 20010041139A1
• Filed: 03/24/1999
• Published: 11/15/2001
• Est. Priority Date: 03/24/1999
• Status: Active Grant

• Current Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: HENYAN, OAKLEY, SABINI, EUGENE P., LORENC, JEROME A.
• Granted Patent: US 6,464,464 B2
• Time in Patent Office: Days
• US Class Current: 417/18
• CPC Class Codes: F04D 15/0066 by changing the speed, e.g. of the driving engine

Abstract

A controller for controlling operating parameters associated with fluid flow, speed or pressure for a centrifugal pump for pumping fluid, wherein at least one sensor is coupled to the pump for generating a signal indicative of a sensed operating condition. The controller comprises a storage device for storing data indicative of at least one operating condition and a processor in communication with the sensor and operative to perform an algorithm utilizing the at least one sensor signal and the stored data indicative of the at least one operating condition to generate a control signal, wherein the control signal is indicative of a correction factor to be applied to the pump.

Claims

1. A controller for controlling operating parameters associated with fluid flow, speed or pressure for a centrifugal pump for pumping fluid, wherein at least one sensor is coupled to said pump for generating a signal indicative of a sensed operating condition, said controller comprising:

a storage device for storing data indicative of an at least one operating condition; and

a processor in communication with said sensor and operative to perform an algorithm utilizing said at least one sensor signal and said stored data indicative of said at least one operating condition to generate a control signal;

wherein said control signal is indicative of a correction factor to be applied to said pump.

2. The controller according to

claim 1

, wherein said correction factor is an increase or reduction in pump motor speed.

3. The controller according to

claim 1

, wherein said control signal is output to an alarm monitor for indicating an alarm condition within said pump.

4. The controller according to

claim 1

, wherein said processor performing said algorithm generates a first control signal indicative of a speed correction factor to be applied to said pump to adjust motor speed, and a second control signal indicative of an alarm condition for output to an alarm monitor for alerting to said sensed operating condition.

5. The controller according to

claim 1

, wherein said storage device comprises a data base, and wherein said stored data comprises physical pump data and site specific data for input to said algorithm.

6. The controller according to

claim 5

, wherein said at least one sensor comprises a suction pressure sensor P_s, a discharge pressure sensor P_d, a differential pressure sensor Δ

P, and a pump speed sensor n, each said sensor generating a corresponding signal indicative of the sensed operating condition.

7. The controller according to

claim 6

, wherein said algorithm comprises:

a) determining the fluid flow;

b) determining pump total dynamic head (TDH);

c) comparing said total dynamic head value with said stored data wherein said control signal is output to an alarm monitor indicating an alarm condition when said determined total dynamic head at said determined flow is less than a preset value associated with said stored data value.

8. The controller according to

claim 7

, wherein said algorithm further comprises:

d) determining net positive suction head available (NPSHa) and

e) comparing with a stored value in the data base corresponding to a threshold value NPSHr based on said pump speed and fluid flow,

wherein said control signal is output to an alarm monitor and indicative of an alarm condition when said NPSHr exceeds said NPSHa.

9. The controller according to

claim 8

, wherein a second control signal is output by said processor for reducing motor speed of said pump by a predetermined amount when NPSHr exceeds NPSHa.

10. The controller according to

claim 9

, wherein said algorithm further comprises:

f) calculating a minimum continuous pump flow and comparing with the determined fluid flow;

wherein a third control signal is output to said alarm monitor indicative of an alarm condition when the determined fluid flow is less than calculated minimum continuous flow.

11. The controller according to

claim 10

, wherein said algorithm further comprises:

g) calculating a minimum allowable pump flow and comparing with the determined fluid flow;

wherein a fourth control signal is output to said alarm monitor indicative of an alarm condition when the determined fluid flow is less than the calculated minimum allowable flow.

12. The controller according to

claim 10

, wherein a fifth control signal is output from said processor for reducing pump speed when said determined fluid flow is less than said minimum allowable flow.

13. A method for automatically controlling operating parameters associated with a centrifugal pump according to an algorithm for pumping fluid to a discharge outlet, comprising:

storing in memory data values corresponding to predetermined operating conditions;

obtaining sensor measurements indicative of current operating conditions;

utilizing said sensor measurements and said stored data values to determine calculated data values corresponding to the current pump operating conditions;

comparing said calculated data values with said stored data values and generating a control signal indicative of a correction factor to be applied to said pump when said calculated data values differ from said stored data values by a predetermined amount.

14. The method according to

claim 13

, wherein said sensor measurements include sensor data associated with pump suction pressure (Pd), discharge pressure (Ps), differential pressure (Δ

P), pump speed (n), and fluid temperature (Tp)

15. The method according to

claim 14

, wherein said calculated data values comprise fluid flow value, pump total dynamic head (TDH), and net positive suction head available (NPSHa).

16. The method according to

claim 15

, wherein said stored data values comprise pump data and site specific data for determining said calculated data values.

17. The method according to

claim 16

, wherein said pump data comprises pump discharge diameter, suction diameter, suction gage height to suction CL difference (Δ

zs), net gage height difference (Δ

Z).

18. The method according to

claim 17

, wherein said pump data further includes minimum continuous capacity (MCFMAX), minimum allowable capacity(AFMAX), TDH as a function of capacity at a plurality of motor speeds, and NPSHr as a function of capacity at a plurality of motor speeds.

19. The method according to

claim 17

, wherein said site specific data includes maximum motor speed (nmax), vapor pressure as a function of temperature (pv), specific gravity as a function of temperature (SPGR), capacity set point (Qset), pressure set point (Pdset), and stability factor (cf).

20. A method of controlling the flow, speed, pressure, or performance of a pumping system comprising the steps of:

storing predetermined data values associated with particular flow, speed, pressure or performance values;

measuring environmental parameter data associated with the pump;

associating subsets of said predetermined stored data values with the measured environmental parameters to obtain calculated data values corresponding to at least one of said flow, speed, performance, or pressure values; and

comparing said calculated data values with a corresponding threshold value and generating a control output signal in response thereto when the difference exceeds a preset value.

21. The method according to

claim 20

, wherein the control signal is indicative of an alarm condition.

22. The method according to

claim 20

, wherein the control signal is indicative of a correction factor to be applied to one of said measured environmental parameters.

23. The method according to

claim 20

, wherein said stored predetermined data values include vapor pressure as a function of temperature, specific gravity as a function of temperature, and pump performance as a function of motor speed.

24. The method according to

claim 23

, wherein said stored predetermined data values further include differential pressure and flow as a function of motor speed and net positive suction head as a function of motor speed.

25. The method according to

claim 24

, wherein said environmental parameters include pump suction pressure, pump discharge pressure, pump speed, and pump differential pressure.

26. The method according to

claim 25

, wherein said environmental parameter data further include pumpage temperature, motor power, and user set points.

27. The method according to

claim 20

, wherein the step of storing predetermined data values comprises the step of storing pumpage fluid specific gravity, fluid vapor pressure, differential pressure and flow as a function of motor speed, pump performance parameters as a function of motor speed, and NPSH parameters as a finction of motor speed.

28. The method according to

claim 27

, wherein the steps of obtaining calculated data values and comparing said calculated data values with a threshold value further comprises:

determining a fluid flow;

calculating a total dynamic head (TDH) value associated with said pump using said determined fluid flow;

selecting from said stored predetermined data values those data values having a speed closest to measured motor speed environmental parameter data;

correcting actual pump flow and said TDH values using said stored predetermined data values associated with pump speed to obtain corrected pump flow and TDH values;

comparing said corrected pump flow and TDH values to said threshold values; and

generating a control signal to activate an alarm in response thereto when the difference is greater than said preset value.

29. The method according to

claim 28

, wherein the steps of obtaining calculated data values and comparing said calculated data values with a threshold value further comprises:

determining net Positive Suction Head Available data value (NPSHa);

comparing said NPSHa with predetermined data values corresponding to a stored value of NPSH; and

generating a second control signal to activate an alarm when the stored value of NPSH is greater than said NPSHa value.

30. The method according to

claim 29

, wherein the steps of obtaining calculated data values and comparing said calculated data values with a threshold value further comprises:

generating a third control signal to reduce motor speed by a predetermined amount when the stored value of NPSH is greater than said NPSHa value.

31. The method according to

claim 29

, wherein the steps of obtaining calculated data values and comparing said calculated data values with a threshold value further comprises:

calculating a minimum continuous pump flow and comparing with the determined fluid flow; and

generating a third control signal to activate an alarm when the determined fluid flow is less than the calculated minimum continuous flow.

32. The controller according to

claim 30

, wherein the steps of obtaining calculated data values and comparing said calculated data values with a threshold value further comprises:

calculating a minimum allowable pump flow and comparing with the determined fluid flow; and

generating a fourth control signal to activate an alarm when the determined fluid flow is less than the calculated minimum allowable flow.

33. The controller according to

claim 28

, wherein the steps of obtaining calculated data values and comparing said calculated data values with a threshold value further comprises:

comparing the determined fluid flow Q with a threshold value Qset corresponding to a user settable fluid flow; and

generating a control signal to adjust motor speed by a factor of (Q/Qset)*n*CF where n is the measured motor speed environmental parameter data and CF represents a user settable value.

34. The controller according to

claim 33

, wherein the steps of obtaining calculated data values and comparing said calculated data values with a threshold value further comprises:

comparing the determined pump discharge pressure Pd with a threshold value Pdset corresponding to a predetermined stored discharge pressure data value; and

generating a control signal to adjust motor speed by a factor of (Pd/Pdset)^ 0.5*n*CF.