Apparatus and method for controlling a pump system

• US 6,709,241 B2
• Filed: 10/15/2002
• Issued: 03/23/2004
• Est. Priority Date: 03/24/1999
• Status: Expired due to Term

• Current Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Sabini, Eugene P., Lorenc, Jerome A., Henyan, Oakley
• Primary Examiner(s): Gartenberg, Ehud
• Application Number:
  US10/271,257
• Publication Number:
  US 20030091443A1
• Time in Patent Office: 525 Days
• Field of Search: 417/18, 417/19, 417/20, 417/43, 417/44.1, 417/44.2, 417/53
• US Class Current: 417/53
• 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 method of controlling the operating parameters associated with fluid flow, speed or pressure of a centrifugal pump of a fluid pumping system comprising the steps of:

storing predetermined data values associated with at least one operating condition of the centrifugal pump;

measuring at least one operating parameter associated with the centrifugal pump;

associating subsets of said predetermined stored data values with the measured operating parameters to obtain calculated data values corresponding to the measured operating parameter; and

comparing said calculated data values with a corresponding threshold value; and

generating a control signal in response thereto for correcting the speed thereof in order to maintain a requisite pump flow or pressure, the control signal including a stability factor that prevents overcorrection of the pump speed.

2. The method according to claim 1, wherein the control signal is indicative of an alarm condition.

3. The method according to claim 1, wherein said stored predetermined data values include vapor pressure as a function of temperature, specific gravity as a function of temperature, and the centrifugal pump performance as a function of the centrifugal pump'"'"'s motor speed.

4. The method according to claim 3, wherein said stored predetermined data values further include differential pressure and flow as a function of the centrifugal pump'"'"'s motor speed and net positive suction head as a function of the centrifugal pump'"'"'s motor speed.

5. The method according to claim 4, wherein said measured operating parameter include pump suction pressure, pump discharge pressure, pump speed, and pump differential pressure.

6. The method according to claim 5, wherein said measured operating parameter further include pumpage temperature, pump motor power, and user set points.

7. The method according to claim 1, 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 function of motor speed.

8. The method according to claim 7, 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 pump motor speed operating parameter;

correcting actual pump flow and said TDH values using said stored predetermined data values associated with pump motor 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 between the corrected pump flow and TDH values and the threshold values is greater than said preset value.

9. The method according to claim 8, 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.

10. The method according to claim 9, 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 pump motor speed by a predetermined amount when the stored value of NPSH is greater than said NPSHa value.

11. The method according to claim 9, 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.

12. The method according to claim 10, 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.

13. A method of controlling the operating parameters associated with fluid flow, speed or pressure of a centrifugal pump of a fluid pumping system comprising the steps of:

storing predetermined data values for 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 function of motor speed;

measuring at least one operating parameter associated with the centrifugal pump;

associating subsets of said predetermined stored data values with the measured operating parameters to obtain calculated data values corresponding to the measured operating parameter; and

comparing said calculated data values with a corresponding threshold value; and

generating a control signal in response thereto for correcting the speed thereof in order to maintain a requisite pump flow or pressure;

the steps of obtaining calculated data values and comparing said calculated data values with the corresponding 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 pump motor speed operating parameter;

correcting actual pump flow and said TDH values using said stored predetermined data values associated with pump motor 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 between the corrected pump flow and TDH values and the threshold values is greater than said preset value;

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

comparing the determined fluid flow Qact 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 Nnew=Nold+((((Qset/Qact)*Nold)−

Nold)*CF) where Nold is the measured motor speed environmental parameter data and CF represents a user settable value.

14. The method according to claim 13, 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 Pdact 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 Nnew=Nold+(((((Pdset/Pdact){circumflex over ( )}0.5)*Nold)−

Nold)*CF).

15. A method of controlling the operating parameters associated with fluid flow, speed or pressure of a centrifugal pump of a fluid pumping system comprising the steps of:

storing data indicative of at least one operating condition of the centrifugal pump;

measuring at least one operating parameter associated with the centrifugal pump; and

generating a control signal which is applied to the centrifugal pump, for correcting the speed thereof in order to maintain a requisite pump flow or pressure, said control signal including a stability factor that prevents overcorrection of said pump speed, wherein the control signal is generated using the measured operating parameter and the stored data.