Simplified fluid property measurement

• US 7,258,024 B2
• Filed: 03/25/2005
• Issued: 08/21/2007
• Est. Priority Date: 03/25/2004
• Status: Active Grant

• Current Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Schumacher, Mark S., Beachey, Terry X., Foster, Jeffry D., Dimarco, Steven J.
• Primary Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US11/090,923
• Publication Number:
  US 20050210998A1
• Time in Patent Office: 879 Days
• Field of Search: 738/612.2, 738/612.4, 738/616.1, 738/612.1
• US Class Current: 73/861.22
• CPC Class Codes: G01F 1/3209 using Karman vortices
• CPC Class Codes: G01F 1/325 Means for detecting quantities used as proxy variables for swirl
• CPC Class Codes: G01F 1/3287 circuits therefor
• CPC Class Codes: G01F 1/86 Indirect mass flowmeters, e.g. measuring volume flow and density, temperature or pressure
• CPC Class Codes: G01F 1/88 with differential-pressure measurement to determine the volume flow
• CPC Class Codes: G01N 2009/006 vibrating tube, tuning fork

Abstract

A process fluid measurement system provides a first measurement relative to process fluid flowing in a pipe. An additional measurement of process fluid flow velocity in the pipe is combined with the first measurement to provide a simplified indication of mass fluid flow and/or density or other fluid parameter. In some embodiments, the first measurement is a differential pressure measurement. Additionally, one embodiment provides a vortex flowmeter having configurable terminations for coupling to a variety of pressure or differential pressure sensors or transmitters for advanced process fluid measurements or calculations.

Claims

1. A system for measuring mass flow of a process fluid in a pipe, the system comprising:

a differential pressure measurement field device adapted to couple to the pipe, the differential pressure measurement field device having a differential pressure sensor to measure process fluid pressure upstream and downstream from a flow interrupter in the pipe;

a fluid velocity device coupled to the pipe and adapted to sense a velocity of fluid flowing in the pipe; and

fluid flow circuitry adapted to combine information from the differential pressure measurement field device and the fluid velocity device to provide an indication of a fluid flow property.

2. The system of claim 1, wherein the fluid flow property is density.

3. The system of claim 1, wherein the fluid flow property is mass flow.

4. The system of claim 1, wherein the fluid velocity device is a vortex sensing device.

5. The system of claim 1, wherein the fluid flow property is calculated by the differential pressure measurement field device.

6. The system of claim 1, wherein the field device communicates the fluid flow property in accordance with a process industry standard communication protocol.

7. The system of claim 1, wherein the fluid velocity device communicates with the differential pressure measurement field device.

8. The system of claim 7, wherein the communication is in accordance with a process industry standard communication protocol.

9. The system of claim 1, wherein the flow interrupter is shaped to generate vortices.

10. The system of claim 9, wherein the fluid velocity device senses a frequency of the vortices.

11. The system of claim 10, wherein the fluid velocity device includes a vortex displaceable member that is disposed downstream from the flow interrupter.

12. The system of claim 11, wherein the vortex displaceable member is coupled to a single side of the pipe.

13. The system of claim 12, wherein the vortex displaceable member includes a longitudinal beam and a thinned area for receiving pressure from a vortex.

14. The system of claim 13, wherein the vortex displaceable member further includes a transverse beam coupled to the longitudinal beam and the thinned area.

15. The system of claim 13, and further comprising a post coupleable to a piezoelectric sensing element such that displacements of the post are detected by the element.

16. The system of claim 1, and further comprising a temperature sensor disposed to provide an indication of process fluid temperature.

17. The system of claim 16, wherein the fluid flow property includes thermal mass flow.

18. The system of claim 16, wherein the fluid flow property is fluid composition.

19. The system of claim 16, wherein the fluid flow property is steam quality.

20. The system of claim 1, wherein the fluid velocity device is a vortex flowmeter field device.

21. The system of claim 1, wherein the differential pressure sensor is formed by a pair of pressure sensors, a first pressure sensor being disposed upstream from the interrupter, and a second pressure sensor being disposed downstream from the interrupter, and wherein at least one of the pair of pressure sensors is formed of a semiconductor material.

22. The system of claim 21, wherein at least one of the pressure sensors is disposed for direct contact with the process fluid.

23. The system of claim 21, wherein the semiconductor material is sapphire.

24. A system for measuring a property of a process fluid in a pipe, the system comprising:

a vortex sensing field device adapted to couple to the pipe and to measure a velocity of the fluid flowing in the pipe, the vortex sensing field device having a plurality of configurable terminations; and

wherein the vortex sensing field device calculates the property of the fluid based upon fluid velocity and a fluid variable measured through the plurality of configurable terminations.

25. The system of claim 24, and further comprising a switch coupled to the plurality of configurable terminations and to a microprocessor in the field device, wherein the microprocessor controls the switch to selectably couple the configurable terminations to an analog-to-digital converter in the vortex sensing field device.

26. The system of claim 24, and further comprising a fluid sensor operably coupled to the plurality of configurable terminations to provide an indication of the fluid variable.

27. The system of claim 26, wherein the fluid sensor is a differential pressure sensor disposed to measure differential pressure across a flow interrupter.

28. The system of claim 24, wherein the property of the process fluid is density.

29. The system of claim 24, wherein the property of the process fluid is mass flow.

30. The system of claim 26, wherein the fluid sensor is a pressure transmitter.

31. The system of claim 30, wherein the pressure transmitter is a differential pressure transmitter.

32. The system of claim 30, wherein the vortex sensing field device includes a resistor coupled across a communication loop of the pressure transmitter.

33. The system of claim 26, wherein the fluid sensor is disposed within a resistor bridge circuit.

34. The system of claim 26, wherein the vortex sensing field device provides power to the fluid sensor.

35. The system of claim 27, wherein the differential pressure sensor provides an indication of differential pressure to the vortex sensing field device in the form of a voltage.

36. The system of claim 26, wherein the vortex sensing field device and the fluid sensor communicate in accordance with a process industry standard communication protocol.

37. The system of claim 36, wherein the protocol is the Controller Area Network protocol.

38. The system of claim 24, wherein the vortex sensing field device communicates the fluid flow property in accordance with a process industry standard communication protocol.

39. The system of claim 27, wherein the vortex sensing field device includes a bluff body that generates and measures vortices in the flowing fluid, and wherein the differential pressure sensor measures a first pressure using a first pressure sensor disposed upstream from the bluff body, and a second pressure sensor disposed downstream from the bluff body.

40. The system of claim 24, and further comprising a temperature sensor operably coupled to the vortex sensing field device and disposed to provide an indication of process fluid temperature.

41. The system of claim 40, wherein the property of the process fluid is thermal mass flow.

42. The system of claim 40, wherein the property of the process fluid is fluid composition.

43. The system of claim 40, wherein the property of the process fluid is steam quality.

44. The system of claim 27, wherein the differential pressure sensor comprises a pair of pressure sensing elements, each element being formed of a semiconductor material.

45. The system of claim 44, wherein the semiconductor material is sapphire.

46. The system of claim 27, wherein the differential pressure sensor is disposed for direct contact with the process fluid.

47. The system of claim 24 wherein the vortex sensing field device is adapted to couple through the plurality of configurable terminations to a fluid sensor selected from the group consisting of an absolute pressure sensor, a gage pressure sensor or a differential pressure sensor.

48. A field device for sensing mass flow of a process fluid in a pipe, the field device comprising:

a vortex generator positionable in the pipe to generate vortices in the fluid as the fluid flows;

a first pressure sensor disposed upstream from the vortex generator to sense an upstream fluid pressure;

a second pressure sensor disposed downstream from the vortex generator, the second pressure sensor providing an indication of vortices and downstream pressure, the second pressure sensor having a plurality of configurable terminations; and

wherein the field device calculates differential pressure from the first and second pressure sensor signals, and calculates vortex frequency from the second pressure sensor signal.

49. The system of claim 48, wherein at least one of the first and second pressure sensors is formed of a semiconductor material.

50. The system of claim 48, wherein at least one of first and second pressure sensors is disposed for direct contact with the process fluid.

51. The system of claim 48, wherein the semiconductor material is sapphire.

52. A method of measuring flow of a process fluid flowing in a pipe with a field device, the method comprising:

providing a flow interrupter in the fluid;

sensing a differential pressure between upstream and downstream locations from the interrupter, through a configurable interface;

measuring fluid velocity; and

calculating, in the field device, mass flow of the fluid based upon the differential pressure and the measured velocity.

53. A method of adjusting a vortex flowmeter having a notch filter, the method comprising:

obtaining a fluid flow rate measurement using the vortex flowmeter;

obtaining a fluid flow measurement using a differential pressure measurement field device; and

adjusting the notch filter of the vortex flowmeter such that the vortex-measured rate matches the differential-pressure measured rate.

54. A method of providing diagnostics relative to a process fluid measurement system, the method comprising:

generating a first process fluid flow rate output with a vortex flowmeter field device coupled to a pipe containing process fluid, the vortex flowmeter field device having a plurality of configurable terminations;

generating a second process fluid flow rate output with a differential pressure flowmeter field device coupled to the pipe; and

comparing the first and second outputs and generating a diagnostic output based upon the comparison.

55. A system for measuring a property of a process fluid in a process fluid container, the system comprising:

a differential pressure measurement field device coupled to the process fluid container, the differential pressure measurement field device for measuring differential pressure across a flow interrupter in the conduit;

means for measuring process fluid velocity coupled to the conduit to sense a velocity of fluid flowing in the conduit, the means for measuring process fluid velocity having a plurality of configurable terminations; and

wherein differential pressure and measured velocity are combined to provide an indication of the property.

56. A field device for sensing a property of a process fluid in a pipe, the field device comprising:

a vortex generator positionable in the pipe to generate vortices in the fluid as the fluid flows;

a vortex sensor disposed to detect the vortices in the fluid;

a controller operably coupled to the vortex sensor to calculate fluid flow rate based on detection of vortices in the fluid by the vortex sensor;

an analog-to-digital converter having an output coupled to the controller;

a plurality of configurable terminations coupled to the controller and to an input of the analog-to-digital converter, the terminations receiving a first input from a fluid sensor to allow the controller to selectively couple the first input to the analog-to-digital converter; and

wherein the controller is configured to calculate the process fluid property based upon the fluid flow rate and a fluid variable measured by the fluid sensor through the configurable terminations.

57. The field device of claim 56, wherein the fluid sensor is a differential pressure sensor disposed to measure differential pressure across a flow interrupter in the pipe.

58. The field device of claim 56, wherein operating power for the differential pressure sensor is provided through the switch.

59. The field device of claim 56, and further comprising a temperature sensor coupled to a third input of the switch, the temperature sensor configured to provide an indication of process fluid temperature to the controller through the switch.

60. The field device of claim 56, wherein the fluid property is selected from the group consisting of mass fluid flow, fluid density, heat content, heat flow, fluid quality and fluid composition.

61. The field device of claim 56 wherein the field device is adapted to couple through the plurality of configurable terminations to a pressure sensor or a differential pressure sensor.