Apparatus and method for proving at low temperatures

• US 8,739,597 B2
• Filed: 04/29/2009
• Issued: 06/03/2014
• Est. Priority Date: 04/30/2008
• Status: Active Grant

• Current Assignee: Emerson Automation Solutions Measurement Systems & Services LLC
• Original Assignee: Daniel Measurement and Control Incorporated (Emerson Electric Company)
• Inventors: Day, Donald
• Primary Examiner(s): Raevis, Robert R
• Application Number:
  US12/990,129
• Publication Number:
  US 20110036178A1
• Time in Patent Office: 1,861 Days
• Field of Search: None
• US Class Current: 73/1.22
• CPC Class Codes: G01F 25/11 using a seal ball or piston in a test loop
• CPC Class Codes: G01F 25/17 using calibrated reservoirs

Abstract

Apparatus and methods for proving a flow meter at low temperatures. A flow meter measuring low temperature fluids (e.g., less than about −50° F., or less than about −220° F.) must still be proved. Low temperature fluids can be destructive to piston or compact provers, or may require indirect proving methods. The apparatus disclosed is a low temperature prover directly coupled into the pipeline carrying the low temperature fluids. In some embodiments, a magnetic pickup coil and a magnetic member communicate between the displacer and the flow tube. The magnetic target member may be carbon-free. In some embodiments, a pair of ultrasonic transceivers coupled to the flow tube communicate a signal across the flow tube and a displacer is moveable to interrupt the signal. In some embodiments, the flow tube includes an inner surface having a microfinish for lubrication. The displacer may be a piston rotatable while being moved axially.

Claims

1. A flow meter prover for low temperature fluids comprising:

an inlet configured to be directly coupled to a pipeline carrying the low temperature fluids;

an outlet configured to be directly coupled to the pipeline carrying the low temperature fluids;

a flow tube coupled between the inlet and the outlet;

a displacer moveable in a flow passage of the flow tube;

wherein the flow tube and the displacer are configured to receive the low temperature fluids; and

at least one of a magnetic pickup coil and a pair of transceivers coupled to the flow tube;

wherein the displacer is configured to communicate with the at least one of the magnetic pickup coil and the pair of transceivers;

wherein the displacer includes a vane disposed at an angle relative to the flow direction of the low temperature fluids.

2. The prover of claim 1 further comprising:

a magnetic member coupled to the displacer communicating with the magnetic pickup coil via magnetic reluctance.

3. The prover of claim 2 wherein the displacer is a piston and the magnetic member is a target ring wrapped around the piston.

4. The prover of claim 1 further comprising:

a carbon-free target member coupled to the displacer communicating with the magnetic pickup coil.

5. The prover of claim 4 wherein the carbon-free target member comprises at least one of high mu (μ

) metal, HYMU metal, and HYMU 80 metal.

6. The prover of claim 4 wherein the carbon-free target member comprises a nickel alloy, an iron alloy, a molybdenum alloy, or any combination of nickel, iron or molybdenum.

7. The prover of claim 1 wherein:

the pair of transceivers communicate a signal across the flow passage in the flow tube; and

the displacer is moveable in the flow passage to interrupt the signal.

8. The prover of claim 1 wherein the flow passage includes an inner surface having a microfinish.

9. The prover of claim 8 wherein the microfinish maintains a microscopic film of the low temperature fluids between the flow passage inner surface and the displacer for lubrication.

10. The prover of claim 8 wherein the microfinish is in the range of 32 microinch to 16 microinch.

11. The prover of claim 1 wherein the displacer is a piston including a set of inner vanes extending along a longitudinal axis of the piston and set at an angle relative to the axis.

12. The prover of claim 1 wherein the vane rotates the displacer in response to the flow of the low temperature fluids.

13. The prover of claim 1 wherein the low temperature fluids include a temperature of less than about −

50°

F.

14. The prover of claim 1 wherein the pair of transceivers comprises a pair of ultrasonic transceivers.

15. The prover of claim 1 wherein the low temperature fluids include at least one of liquid natural gas (LNG), liquid nitrogen, liquid butane, liquid propane, and liquefied petroleum gas (LPG).

16. A flow meter prover for low temperature fluids comprising:

a flow tube having a flow passage therein and a magnetic pickup coil mounted thereon; and

a piston disposed in the flow passage and including a carbon-free magnetic member;

wherein the piston is moveable to move the magnetic member past the magnetic pickup coil and communicate with the magnetic pickup coil via magnetic reluctance;

wherein an inner surface of the flow passage includes a microfinish configured to maintain a lubricating microfilm of the low temperature fluids;

wherein the carbon-free magnetic member comprises at least one of high mu (μ

) metal, HYMU metal, and HYMU 80 metal.

17. The prover of claim 16 wherein the piston includes a set of piston rotating vanes.

18. The prover of claim 16 further comprising:

a pair of ultrasonic transceivers disposed on the flow tube and communicating across the flow passage; and

wherein the piston movement interrupts the ultrasonic transceiver communication.

19. A system for proving low temperature fluids comprising:

a pipeline carrying the low temperature fluids;

a prover coupled into the pipeline and receiving the low temperature fluids, wherein the prover comprises;

a flow tube including a piston moveably disposed therein; and

at least one of a magnetic pickup coil and a pair of transceivers coupled to the flow tube;

wherein the piston is configured to communicate with the at least one of the magnetic pickup coil and the pair of transceivers;

wherein an inner surface of the flow tube includes a microfinish configured to maintain a lubricating microfilm of the low temperature fluids;

wherein the piston is configured to rotate while being moved axially.

20. The system of claim 19 wherein the pair of transceivers comprises a pair of ultrasonic transceivers.

21. The system of claim 19 wherein the low temperature fluids include a temperature of less than about −

220°

F.

22. The system of claim 19 wherein the piston includes a carbon-free magnetic target member.