Flow measurement module and method

• US 6,725,167 B2
• Filed: 01/16/2002
• Issued: 04/20/2004
• Est. Priority Date: 01/16/2002
• Status: Active Grant

• Current Assignee: Fisher Controls International LLC (Emerson Electric Company)
• Original Assignee: Fisher Controls International LLC (Emerson Electric Company)
• Inventors: Adams, Paul Robert, Grumstrup, Bruce Frederick
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): LE, JOHN H
• Application Number:
  US10/050,450
• Publication Number:
  US 20030135335A1
• Time in Patent Office: 825 Days
• Field of Search: 702/45, 702/47, 702/50, 702/52, 702/53, 731/181, 731/522.4, 731/68, 731/99, 73/1, 137/8, 137/487.5, 700/282
• US Class Current: 702/47
• CPC Class Codes: G01F 1/36 the pressure or differential pressure being created by the use of flow constriction
• CPC Class Codes: G01F 1/363 with electrical or electro-mechanical indication G01F1/37 and G01F1/38 take precedence
• CPC Class Codes: G01F 1/40 Details of construction of the flow constriction devices
• CPC Class Codes: G01F 15/003 using electromagnetic, electric or electronic means G01F15/002, G01F15/02 take precedence
• CPC Class Codes: G01F 15/005 Valves valves in general F16K
• CPC Class Codes: G05D 7/0635 by action on throttling means G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve

Abstract

A flow measurement module is adapted to operate in conjunction with a control valve assembly to measure a flow rate of a fluid though a flow passage regulated by the control valve assembly. The flow measurement module is communicatively coupled to an intelligent positioner within the control valve assembly to receive data pertaining to the position of the throttling element within the flow passage. The position of the throttling element is used to identify at least one associated valve sizing coefficient. The flow measurement module determines the flow rate of the fluid through the flow passage based on a sensed upstream pressure, a sensed downstream pressure and the valve sizing coefficient associated with the position of the throttling element within the flow passage.

Claims

1. A flow measurement module adapted to operate in conjunction with an existing control valve assembly having an associated control system the control valve assembly including a valve assembly including a throttling element moveable within the flow passage and an intelligent positioner adapted to sense the approximate position of the throttling element within the flow passage and responsively generate a representative position feedback signal, the control system being communicatively coupled to the intelligent positioner to deliver a position setpoint signal to the intelligent positioner and receive the position feedback signal from the intelligent positioner, the flow measurement module comprising:

a first communication port adapted to receive an upstream pressure signal representative of a sensed pressure upstream of the throttling element;

a second communication port adapted to receive a downstream pressure signal representative of a sensed pressure downstream of the throttling element;

a third communication port adapted to receive the position feedback signal representative of the approximate position of the throttling element within the flow passage without disrupting the flow of fluid through the flow passage; and

a controller communicatively coupled to the first, second and third communication ports, the controller being adapted to operate in accordance with a computer program embodied on a computer readable medium, the computer program comprising;

a first routine that directs the controller to determine a valve sizing coefficient based on the received position feedback signal; and

a second routine that directs the controller to determine the flow rate of the fluid flowing through the flow passage based on the determined valve sizing coefficient, the received upstream pressure signal and the received downstream pressure signal.

2. The flow measurement module of claim 1, further including a memory communicatively coupled to the controller, the memory being adapted to store a plurality of different throttling element positions and a plurality of valve sizing coefficients where each stored throttling element position is associated with at least one valve sizing coefficient.

3. The flow measurement module of claim 2, wherein the memory is adapted to receive the plurality of valve sizing coefficients associated with each of a plurality of the throttling element positions via a software download.

4. The flow measurement module of claim 2, wherein the memory is adapted to receive the plurality of valve sizing coefficients associated with each of the plurality of throttling element positions as entered individually by a user via a user interface.

5. The flow measurement module of claim 2, wherein the memory is adapted to store a first set of selectable valve sizing coefficients for use with a first control valve and a second set of selectable valve sizing coefficients for use with a second control valve.

6. The flow measurement module of claim 2, wherein the first routine directs the controller to retrieve from memory the valve sizing coefficient associated with the approximate position of the throttling element as indicated by the position feedback signal.

7. The flow measurement module of claim 1, wherein the first routine directs the controller to determine the valve sizing coefficient associated with the approximate position of the throttling element in accordance with an equation representative of a relationship between a position of the throttling element and an associated valve sizing coefficient.

8. The flow measurement nodule of claim 1, further including a first pressure sensor adapted to sense the pressure upstream of the throttling element and responsively generate the upstream pressure signal.

9. The flow measurement module of claim 1, further including a second pressure sensor adapted to sense the pressure downstream of the throttling element and responsively generate the downstream pressure signal.

10. The flow measurement module of claim 1, wherein the third communication port is adapted to be communicatively coupled to the intelligent positioner to receive the position feedback signal.

11. The flow measurement module of claim 1, wherein the third communication port is adapted to be communicatively coupled to the control system to receive the position feedback signal.

12. The flow measurement module of claim 1, further including a memory, the memory being adapted to store a specific gravity of the fluid flowing through the flow passage.

13. The flow measurement module of claim 1, wherein the first routine directs the controller to determine a liquid valve sizing coefficient based on the received position feedback signal.

14. The flow measurement module of claim 13, wherein the second routine directs the controller to issue a flow rate signal representative of the flow rate Q of a liquid fluid flowing through the flow passage in accordance with

15. The flow measurement module of claim 1, further comprising a fourth communication port adapted to receive a temperature signal representative of a sensed temperature of the fluid flowing through the flow passage.

16. The flow measurement module of claim 15, further including a temperature sensor adapted to sense the temperature of the fluid upstream of the throttling element and responsively generate the temperature signal.

17. The flow measurement module of claim 1, further including a memory, the memory being adapted to store a fluid temperature.

18. The flow measurement module of claim 1, wherein the first routine directs the controller to determine a gas valve sizing coefficient based on the received position feedback signal.

19. The flow measurement module of claim 18, wherein the first routine directs the controller to determine a liquid valve sizing coefficient based on the received position feedback signal and to generate a valve recovery coefficient based on the determined gas valve sizing coefficient and the determined liquid valve sizing coefficient.

20. The flow measurement module of claim 1, wherein the first routine directs the controller to determine a gas sizing coefficient and a valve recovery coefficient based on the received position feedback signal.

21. The flow measurement module of claim 20, wherein the second routine directs the controller to issue a flow rate signal representative of the flow rate Q of a gas fluid flowing through the flow passage in accordance with:

$Q=\sqrt{\frac{520}{\mathrm{GT}}}<br><br>\mathrm{CgP1}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{SIN}<br><br>\left[\left(\frac{3417}{\mathrm{C1}}\right)<br><br>\sqrt{\frac{\mathrm{P1}-\mathrm{P2}}{\mathrm{P1}}}\right]<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Degrees}$

where

Q is the flow rate of the gas,

Cg is the gas valve sizing coefficient associated with the approximate position of the throttling element,

C1 is the valve recovery coefficient associated with the approximate position of the throttling element,

G is a specific gravity of the gas,

T is a temperature of the fluid flowing through the flow passage,

P1 is the sensed upstream pressure, and

P2 is the sensed downstream pressure.

22. A method of measuring a flow rate of a fluid though a flow passage regulated by an existing control valve assembly having an associated control system, the control valve assembly including a valve assembly including a throttling element moveable within the flow passage and an intelligent positioner adapted to sense the approximate position of the throttling element within the flow passage and responsively generate a representative position feedback signal, the control system being communicatively coupled to the intelligent positioner to deliver a position setpoint signal to the intelligent positioner and receive the position feedback signal from the intelligent positioner, the method comprising the steps of:

providing a flow measurement module including a controller communicatively coupled to a memory and to first, second and third communication ports;

communicatively coupling the flow measurement module to the intelligent positioner via the first communication port without disrupting flow of fluid through the fluid passage;

receiving the position feedback signal representative of the approximate position of the throttling element within the flow passage via the first communication port;

receiving an upstream pressure signal representative of the sensed pressure upstream of the throttling element via the second communication port;

receiving a downstream pressure signal representative of the sensed pressure downstream of the throttling element via the third communication port;

determining a valve sizing coefficient based on the approximate position of the throttling element as indicated by the received position feedback signal; and

determining a flow rate of the fluid flowing through the flow passage based on the sensed upstream pressure, the sensed downstream pressure and the determined valve sizing coefficient.

23. The method of claim 22, further comprising the steps of storing a plurality of throttling element positions in a memory communicatively coupled to the controller and storing a plurality of valve sizing coefficients in the memory where each stored throttling element position is associated with at least one valve sizing coefficient.

24. The method of claim 23, wherein the step of determining the valve sizing coefficient further includes the step of retrieving from the memory the valve sizing coefficient associated with the approximate position of the throttling element as indicated by the position feedback signal.

25. The method of claim 23, further comprising the step of receiving the plurality of valve sizing coefficients associated with each of the plurality of throttling element positions via a software download.

26. The method of claim 23, further comprising the step of receiving the plurality of valve sizing coefficients associated with each of the plurality of throttling element positions as entered individually by a user via a user interface.

27. The method of claim 23, further comprising the step of storing a first set of selectable valve sizing coefficients for use with a first control valve and storing a second set of selectable valve sizing coefficients for use with a second control valve.

28. The method of claim 27, further comprising the step of selecting the first stored set of selectable valve sizing coefficients if a first control valve is used to regulate the flow of fluid in the flow passage.

29. The method of claim 22, wherein the step of determining the valve sizing coefficient further includes the step of determining the valve sizing coefficient associated with the approximate position of the throttling element in accordance with an equation representative of the relationship between a position of the throttling element and an associated valve sizing coefficient.

30. The method of claim 22, further including the step of communicatively coupling the flow measurement module to the control system without disrupting the flow of fluid through the flow passage.

31. The method of claim 22, further including the step of storing a specific gravity of a fluid flowing through the flow passage in a memory, the memory being communicatively coupled to the controller.

32. The method of claim 22, wherein the step of determining the valve sizing coefficient further comprises determining the liquid valve sizing coefficient based on the approximate position of the throttling element as indicated by the received position feedback signal.

33. The method of claim 32, wherein the step of determining the flow rate of the fluid through the flow passage further comprises determining the flow rate Q of a liquid fluid in accordance with

34. The method of claim 22, further comprising the step of receiving a temperature signal representative of a sensed temperature of the fluid flowing through the flow passage via a fourth communication port, the fourth communication port being communicatively coupled to the controller.

35. The method of claim 22, further comprising the step of storing the approximate temperature of the fluid flowing through the flow passage in a memory, the memory being communicatively coupled to the controller.

36. The method of claim 22, wherein the step of determining the valve sizing coefficient further includes determining a gas valve sizing coefficient based on the approximate position of the throttling element as indicated by the received position feedback signal.

37. The method of claim 36, wherein the step of determining the valve sizing coefficient further comprises the steps of:

determining a liquid valve sizing coefficient based on the approximate position of the throttling element as indicated by the received position feedback signal; and

generating a valve recovery coefficient based on the determined gas valve sizing coefficient and the determined liquid valve sizing coefficient.

38. The method of claim 22, wherein the step of determining the valve sizing coefficient further includes determining a gas valve sizing coefficient and a valve recovery coefficient based on the approximate position of the throttling element as indicated by the received position feedback signal.

39. The method of claim 38, wherein the step of determining the flow rate of the fluid through the flow passage further comprises determining the flow rate Q of a gas fluid flowing through the flow passage in accordance with $Q=\sqrt{\frac{520}{\mathrm{GT}}}$

Cg

P1

SIN

[(3417C1)

P1-P2P1]

 



Degrees

where

Q is the flow rate of the gas,

Cg is the gas valve sizing coefficient associated with the approximate position of the throttling element,

C1 is the valve recovery coefficient associated with the approximate position of the throttling element,

G is a specific gravity of the gas,

T is a temperature of the fluid flowing through the flow passage,

P1 is the sensed upstream pressure, and

P2 is the sensed downstream pressure.

40. The method of claim 22, further including the step of storing the determined flow rate in a flow measurement module memory.

41. The method of claim 40, further including the step of retrieving the stored flow rate via a local data retrieval device.

42. The method of claim 22, further including the step of displaying the determined flow rate on a flow measurement module display unit.

43. The method of claim 22, further including the steps of communicatively coupling the flow measurement module to a process control system device and communicating the determined flow rate to the process control system device.