Pipeline pressure control system

• US 4,934,399 A
• Filed: 04/25/1989
• Issued: 06/19/1990
• Est. Priority Date: 04/25/1989
• Status: Expired due to Fees

• Current Assignee: Fisher-Rosemount Systems Incorporated (Emerson Electric Company)
• Original Assignee: Fisher Controls International LLC (Emerson Electric Company)
• Inventors: Cho, Chun H.
• Primary Examiner(s): Cohan, Alan
• Application Number:
  US07/343,152
• Time in Patent Office: 420 Days
• Field of Search: 137/14, 137/1, 137/487.5, 137/486
• US Class Current: 137/14
• CPC Class Codes: G05D 16/2013 using throttling means as controlling means
• CPC Class Codes: Y10T 137/0396 Involving pressure control
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve

Abstract

A pipeline pressure control system for minimizing pressure surges within a pipeline includes a suction pressure controller connected to a suction pressure transmitter for sensing the pipeline pressure upstream of a valve and a discharge pressure controller connected to a discharge pressure transmitter for sensing the pipeline pressure downstream of the valve. If either the suction pressure controller or the discharge pressure controller senses a pressure that varies more than a predetermined amount from a predetermined target pressure, the valve will automatically be moved to a predetermined position in order to counteract pressure surges.

Claims

1. A pressure control system that responds to pressure surges in a pipeline by changing the pipeline pressure in the direction opposite the pressure surge, said pressure control system comprising:

a pipeline;

a valve coupled to said pipeline for varying the flow of fluid through said pipeline;

a suction pressure sensor coupled to said pipeline upstream of said valve for sensing the suction pressure of the fluid within said pipeline;

a discharge pressure sensor coupled to said pipeline downstream of said valve for sensing the discharge pressure of the fluid within said pipeline;

a suction controller coupled to said suction pressure sensor, said suction controller comparing the suction pressure sensed by said suction pressure sensor with a first predetermined pressure setpoint to determine when the suction pressure is lower than said first pressure setpoint by more than a first predetermined amount of at least approximately five psi; and

a discharge controller coupled to said discharge pressure sensor, said discharge controller comparing the discharge pressure sensed by said discharge pressure sensor with a second predetermined pressure setpoint to determine when the discharge pressure exceeds said second pressure setpoint by more than a second predetermined amount of at least approximately five psi,

said valve being moved to a predetermined position in response to either said suction controller determining that the suction pressure is lower than said first pressure setpoint by more than said first predetermined amount or said discharge controller determining that the discharge pressure exceeds said second pressure setpoint by more than said second predetermined amount.

2. A pressure control system as defined in claim 1 wherein said discharge controller causes said valve to be moved to said predetermined position.

3. A pressure control system as defined in claim 1 wherein said first predetermined pressure setpoint is in the approximate range of 20-100 psi and said second predetermined pressure setpoint is in the approximate range of 500-2,000 psi.

4. A pressure control system as defined in claim 3 wherein said first predetermined amount is approximately equal to said second predetermined amount.

5. A pressure control system as defined in claim 4 wherein said first and said second predetermined amounts are approximately five psi.

6. A pipeline pressure control system that responds to a pressure surge in a pipeline by changing the pipeline pressure in the direction opposite the pressure surge, said pressure control system comprising:

a pipeline;

a valve coupled to said pipeline for varying the flow of fluid through said pipeline;

a pressure sensor coupled to said pipeline for sensing the pressure of the fluid within said pipeline; and

a controller coupled to said pressure sensor and said valve for controlling said valve, said controller causing said valve to be moved from an initial position to a predetermined position in response to said pressure sensor sensing a pressure that varies from a predetermined pressure setpoint by at least a predetermined amount, whereby the pipeline pressure is changed in the direction opposite the pressure surge.

7. A pipeline pressure control system as defined in claim 6 wherein said controller causes said valve to be moved to said predetermined position in response to said pressure sensor sensing a pressure that is greater than said predetermined amount above said predetermined pressure setpoint.

8. A pipeline pressure control system as defined in claim 6 wherein said initial value position is more open than said predetermined valve position.

9. A pressure control system as defined in claim 6 wherein said predetermined amount is approximately five psi.

10. A pressure control system that responds to a pressure surge in a conduit by changing the conduit pressure in the direction opposite the pressure surge, said pressure control system comprising:

a conduit;

a valve coupled to said conduit for varying the flow of fluid through said conduit;

a pressure sensor coupled to said conduit for sensing the pressure of the fluid within said conduit; and

a controller coupled to said pressure sensor and said valve for controlling said valve, said controller causing said valve to be moved to a predetermined position in response to said pressure sensor sensing a pressure that varies from a predetermined pressure by at least a predetermined amount, whereby the conduit pressure is changed in the direction opposite the pressure surge.

11. A pressure control system as defined in claim 10 wherein said predetermined amount is approximately five psi.

12. A pressure control system that responds to a pressure surge in a conduit by changing the conduit pressure in the direction opposite the pressure surge, said pressure control system comprising:

a conduit;

a valve coupled to said conduit for varying the flow of fluid through said conduit;

a pressure sensor coupled to said conduit for sensing the pressure of the fluid within said conduit; and

control means coupled to said valve and said pressure sensor for controlling the position of said valve, said control means causing said valve to be moved to a predetermined position in response to said pressure sensor sensing a pressure that varies from a predetermined pressure by at least a predetermined amount, whereby the conduit pressure is changed in the direction opposite the pressure surge.

13. A method of controlling a valve in which a pressure surge in a conduit is counteracted by changing the conduit pressure in the direction opposite the pressure surge, said method comprising the steps of:

(a) sensing the pressure upstream of a valve within a conduit;

(b) determining the difference between the pressure sensed in said step (a) and a first predetermined pressure;

(c) comparing the pressure difference determined in said step (b) with a first predetermined pressure difference;

(d) moving the valve to a first predetermined position if the pressure difference determined in said step (b) is greater than said first predetermined pressure difference;

(e) sensing the internal conduit pressure downstream of the valve;

(f) determining the difference between the pressure sensed in said step (e) and a second predetermined pressure;

(g) comparing the pressure difference determined in said step (f) with a second predetermined pressure difference; and

(h) moving the valve to a second predetermined position if the pressure difference determined in said step (f) is greater than said second predetermined pressure difference.

14. A method as defined in claim 13 wherein said steps (a)-(c) are performed substantially simultaneously with and independently of said steps (e)-(g).

15. A method as defined in claim 13 wherein said first predetermined pressure difference is approximately five psi.

16. A method of controlling a valve in which a pressure surge in a conduit is counteracted by changing the conduit pressure in the direction opposite the pressure surge, said method comprising the steps of:

(a) sensing the pressure within a conduit;

(b) determining the difference between the pressure sensed in said step (a) and a predetermined pressure;

(c) comparing the pressure difference determined in said step (b) with a predetermined pressure difference; and

(d) moving a valve to a predetermined position if the pressure difference determined in said step (b) is greater than said predetermined pressure difference, whereby the conduit pressure is changed in the direction opposite the pressure surge.

17. A method as defined in claim 16 wherein said predetermined pressure difference is approximately five psi.

18. A method of controlling a valve in which a pressure surge in a conduit is counteracted by changing the conduit pressure in the direction opposite the pressure surge, said method comprising the steps of:

(a) sensing the pressure within a conduit;

(b) determining the difference between the pressure sensed in said step (a) and a predetermined pressure;

(c) comparing the pressure difference determined in said step (b) with a predetermined pressure difference; and

(d) if the pressure difference determined in said step (b) is greater than said predetermined pressure difference, moving a valve coupled to the conduit from an initial position to a predetermined position, whereby the conduit pressure is changed in the direction opposite the pressure surge;

or

(e) if the pressure difference determined in said step (b) is less than said predetermined pressure difference and the pressure sensed in said step (a) is beyond said predetermined pressure, moving the valve from an initial position to a new position based upon the pressure difference determined in said step (b).

19. A method as defined in claim 18 wherein said predetermined pressure difference is approximately five psi.

20. A method of controlling a valve in which a pressure surge in a conduit is counteracted by changing the conduit pressure in the direction opposite the pressure surge, said method comprising the steps of:

(a) sensing the pressure upstream of a valve within a conduit;

(b) determining the difference between the pressure sensed in said step (a) and a first predetermined pressure;

(c) comparing the pressure difference determined in said step (b) with a first predetermined pressure difference;

(d) if the pressure difference determined in said step (b) is greater than said first predetermined pressure difference, determining a new valve position based upon a first predetermined valve position;

or

(e) if the pressure difference determined in said step (b) is less than said first predetermined pressure difference and the pressure sensed in said step (a) is less than said first predetermined pressure, determining a new valve position based upon the difference determined in said step (b);

(f) sensing the pressure downstream of the valve within the conduit;

(g) determining the difference between the pressure sensed in said step (f) and a second predetermined pressure;

(h) comparing the pressure difference determined in said step (g) with a second predetermined pressure difference; and

(i) if the pressure difference determined in said step (g) is greater than said second predetermined pressure difference, determining a new valve position based upon a second predetermined valve position;

or

(j) if the pressure difference determined in said step (g) is less than said second predetermined pressure difference and the pressure sensed in said step (f) is greater than said second predetermined pressure, determining a new valve position based upon the difference determined in said step (g);

(k) comparing the new valve position determined in said step (d) or (e) with the new valve position determined in said step (i) or (j) to determine the most closed valve position; and

(l) moving the valve to the most closed valve position determined in said step (k).

21. A method as defined in claim 20 wherein said first predetermined valve position is different from said second predetermined valve position.

22. A method as defined in claim 20 wherein said first predetermined pressure difference is the same as said second predetermined pressure difference.

23. A method as defined in claim 22 wherein said second predetermined pressure difference is approximately five psi.

24. A method of controlling a valve comprising the steps of:

(a) sensing the pressure within a conduit;

(b) determining the difference between the pressure sensed in said step (a) and a predetermined pressure;

(c) comparing the pressure difference determined in said step (b) with a predetermined pressure difference of approximately five psi; and

(d) if the pressure difference determined in said step (b) is greater than said five psi pressure difference, moving a valve coupled to the conduit from an initial position to a predetermined position;

or

(e) if the pressure difference computed in said step (b) is less than said five psi pressure difference and the pressure sensed in said step (a) is beyond said predetermined pressure, moving the valve from an initial position to a new position based upon the pressure difference determined in said step (b).

25. A pipeline pressure control system that responds to a pressure surge in a pipeline by changing the pipeline pressure in the direction opposite the pressure surge, said pressure control system having a predetermined shutdown pressure, said pressure control system comprising:

a pipeline;

a valve coupled to said pipeline for varying the flow of fluid through said pipeline;

a pressure sensor coupled to said pipeline for sensing the pressure of the fluid within said pipeline; and

a controller coupled to said pressure sensor and said valve for controlling said valve, said controller causing said valve to be moved from an initial position to a predetermined position in response to said pressure sensor sensing a pressure that varies from a predetermined pressure setpoint by at least a predetermined amount, whereby the pipeline pressure is changed in the direction opposite the pressure surge, said predetermined amount being substantially less than the difference between said predetermined pressure setpoint an said predetermined shutdown pressure.

26. A pressure control system having a predetermined shutdown pressure, comprising:

a conduit;

a valve coupled to said conduit that varies the flow of fluid through said conduit, said valve having a first position corresponding to a predetermined pressure setpoint and a second position corresponding to a predetermined position different than said first position;

a pressure sensor coupled to said conduit that senses the pressure of the fluid within said conduit; and

a controller coupled to said pressure sensor and said valve that controls said valve, said controller causing said valve to be moved in said second position in response to said pressure sensor sensing a pressure that varies from a predetermined pressure by at least a predetermined amount, said predetermined amount being substantially less than the difference between said predetermined pressure setpoint and said predetermined shutdown pressure.

27. A pressure control system comprising:

a conduit;

a valve coupled to said conduit that varies the flow of fluid through said conduit, said valve having a first position corresponding to a predetermined pressure setpoint and a second position corresponding to a predetermined position different than said first position;

a pressure sensor coupled to said conduit that senses the pressure of the fluid within said conduit; and

a controller coupled to said pressure sensor and said valve that controls said valve, said controller causing said valve to be moved to said second position in response to said pressure sensor sensing a pressure that varies from a predetermined pressure by at least a predetermined amount.

28. A method of controlling a valve comprising the steps of:

(a) sensing the pressure within a conduit;

(b) determining the difference between the pressure sensed in said step (a) and a predetermined target pressure;

(c) comparing the pressure difference determined in said step (b) with a predetermined pressure difference; and

(d) moving a valve to a predetermined position if the pressure difference determined in said step (b) is greater than said predetermined pressure difference, said predetermined position being a position different than the position of the valve corresponding to said predetermined target pressure.