MEANS AND METHOD FOR MONITORING THE FLOW OF FLUID

• US 20130036817A1
• Filed: 04/18/2011
• Published: 02/14/2013
• Est. Priority Date: 04/17/2010
• Status: Active Grant

• Current Assignee: University of Huddersfield
• Original Assignee: University of Huddersfield
• Inventors: Lucas, Gary P., Leeungculsatien, Teerachai
• Granted Patent: US 9,163,967 B2
• Time in Patent Office: Days
• US Class Current: 73/32.R
• CPC Class Codes: G01F 1/586 constructions of coils, magnetic circuits, accessories therefor G01F1/582 takes precedence; magnet; inductances; transformers; selection of materials for their magnetic properties per se H01F
• CPC Class Codes: G01F 1/588 combined constructions of electrodes, coils or magnetic circuits, accessories therefor
• CPC Class Codes: G01F 1/60 Circuits therefor
• CPC Class Codes: G01F 1/712 using auto-correlation or cross-correlation detection means
• CPC Class Codes: G01F 1/74 Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid

Abstract

The invention relates to an means and method for monitoring the flow of a fluid. The invention relates to an electromagnetic flow meter and method for measuring the axial velocity profile of a conducting fluid. The conducting fluid may be a conducting single phase fluid or a conducting continuous phase of a multiphase fluid. The conducting fluid may have a uniform flow profile or a non-uniform flow profile. The electromagnetic flow meter and method measure the axial velocity profile of a conducting fluid by dividing the flow cross section into multiple pixels and determining the axial velocity of the conducting fluid in each pixel. Having. derived the axial velocity profile, the electromagnetic flow meter and method may further derive the volumetric flow rate of the conducting fluid. The electromagnetic flow meter and method may be suitable for measuring the axial velocity profile and optionally the volumetric flow rates of each phase of a multiphase fluid.

Claims

1. An electromagnetic flow meter for monitoring the flow of a conducting fluid comprising:

a flow tube;

a means for generating a magnetic field across the flow tube cross-section so that a voltage is induced in the conducting fluid as it flows through the flow tube;

an array of voltage detection electrodes configured to divide the flow cross-section into multiple pixel regions and measure the induced voltage in each pixel region; and

processing means for determining the axial velocity profile of the conducting fluid by calculating the local axial velocity of the conducting fluid in each pixel region.

2. The flow meter of claim 1, wherein the flow tube comprises a non-electrically conducting body.

3. The flow meter of claim 1, wherein the flow tube comprises:

an outer body portion formed from a low magnetic permeability material; and

an inner body portion formed from a non-electrically conducting material.

4. The flow meter of claim 1 wherein the flow tube further comprises an annular liner having a conductivity that is generally the same as the conductivity of the conducting fluid.

5. The flow meter of any of claim 1, wherein the means for generating a magnetic field comprises a Helmholtz coil having a pair of coils arranged symmetrically on opposing sides of the flow tube.

6. The flow meter of claim 5, wherein the means for generating a magnetic field is configured to generate a substantially uniform magnetic field across the flow tube cross-section.

7. The flow meter of claim 5, wherein the means for generating a magnetic field is configured to generate a non-uniform magnetic field across the flow tube cross-section.

8. The flow meter of any of claim 5, wherein the means for generating a magnetic field is configured to generate a magnetic field having a single magnetic field projection (P=1).

9. The flow meter of any of claim 5, wherein the means for generating a magnetic field is configured to successively generate multiple magnetic fields, each magnetic field having a different magnetic field projections (P>

1).

10. The flow meter of claim 1, whereby the array of electrodes comprises E electrodes that are configured to divide the flow cross section up to M pixel regions and measure up to M induced voltages in the conducting fluid when a single magnetic field projection is applied, whereby M=E−

1.

11. The flow meter of claim 10, wherein the means for generating a magnetic field is configured to successively generate multiple magnetic fields, each magnetic field having a different magnetic field projections (P>

1), and wherein the array of E electrodes is configured to divide the flow cross section into N pixel regions and measure up to N induced voltages in the conducting fluid when multiple magnetic field projections are applied, whereby N=PM.

12. The flow meter of claim 1, wherein the processing means is configured to calculate the local axial velocity of the conducting fluid in each said pixel region using the measured induced voltage for each said pixel region and predetermined weight functions for each said pixel region.

13. The flow meter of claim 12, wherein the processing means is configured to calculate the volumetric flow rate of the conducting fluid.

14. The flow meter of claim 13, whereby when the conducting fluid is a conducting single phase fluid, the processing means is configured to calculate the volumetric flow rate using the local axial velocity of the conducting fluid in each pixel region.

15. The flow meter of claim 13, whereby when the conducting fluid is a conducting continuous phase of a multiphase fluid, the processing means is configured to calculate the volumetric flow rate using the local axial velocity in each pixel region and local concentration distribution of the conducting fluid.

16. The flow meter of claim 15, further comprising means for measuring the local concentration distribution of the conducting continuous phase of the multiphase fluid and optionally the local concentration distribution of the one or more dispersed phases of the multiphase fluid.

17. The flow meter of claim 16, wherein the means for measuring the local concentration distribution is configured to use an electrical resistance tomography technique or an impedance cross correlation technique.

18. The flow meter of claim 16, further comprising means for determining the mean density of the multiphase fluid and means for determining the density of each phase of a multiphase fluid.

19. The flow meter of claim 16, wherein the flow meter is configured to determine the axial velocity profile, and optionally the volumetric flow rate, of each phase of a multiphase fluid.

20. The flow meter of claim 12, wherein the processing means comprises means for controlling the operation of the means for generating the magnetic field.

21. The flow meter of claim 20, wherein the means for generating a magnetic field comprises a Helmholtz coil having a pair of coils arranged symmetrically on opposing sides of the flow tube, and wherein the means for controlling the operation of the means for generating the magnetic field comprises a coil excitation circuit for controlling the flow of current to the Helmholtz coil.

22. The flow meter of claim 21, wherein the processing means comprises a temperature compensating circuit to compensate for the change in the resistance of the Helmholtz coil as the temperature varies.

23. The flow meter of claim 12, wherein the processing means comprises means for collating the induced voltages.

24. The flow meter of claim 23, wherein the processing means comprises a control circuit to compensate for the effects of any unwanted voltage components.

25. A method for monitoring the flow of a conducting fluid comprising:

generating an induced voltage in the conducting fluid;

measuring the induced voltage in multiple pixel regions across the flow cross-section;

determining the axial velocity profile of the conducting fluid by calculating the local axial velocity of the conducting fluid in each pixel region.

26. The method of claim 25, wherein calculating the local axial velocity of the conducting fluid in each pixel region comprises using the measured induced voltages and predetermined weight functions.

27. The method of claim 25 further comprising determining the weight functions for each pixel in the flow cross-section prior to monitoring the flow of the conducting fluid.

28. The method of claim 25 further comprising applying a magnetic field with a single magnetic field projection across the conducting fluid so as to induce a voltage in the conducting fluid, whereby the magnetic field is a uniform magnetic field or a non-uniform magnetic field.

29. The method of claim 28 further comprising successively applying multiple magnetic fields across the conducting fluid, whereby each magnetic field has a different magnetic field projection.

30. The method of claim 25 further comprising determining the volumetric flow rate of the conducting fluid.

31. The method of claim 30, wherein, when the conducting fluid is a conducting single phase fluid, determining the volumetric flow rate of the conducting fluid comprises using the axial velocity profile of the conducting fluid.

32. The method of claim 30, wherein when the conducting fluid is a conducting continuous phase of a multiphase fluid, determining the volumetric flow rate of the conducting fluid comprises using the axial velocity profile and local concentration distribution of the conducting fluid.

33. The method of claim 32, further comprising measuring the local concentration distribution of the conducting fluid and optionally measuring the local concentration distribution of one or more dispersed phases.

34. The method of claim 33, wherein measuring the local concentration distribution of the conducting fluid comprises using an electrical resistance tomography technique or an impedance cross correlation technique.

35. The method of claim 33 further comprising determining the axial velocity profile, and optionally the volumetric flow rate, of each phase of the multiphase fluid.

36. The method of claim 25 further comprising controlling the magnetic field.

37. The method of claim 36, wherein when the magnetic field is generated by a Helmholtz coil, the controlling of the magnetic field comprises controlling the flow of current to the Helmholtz coil.

38. The method of claim 36, further comprising compensating for a variation in the magnetic field due to temperature fluctuations.

39. The method of claim 25, further comprising collating the induced voltages.

40. The method of claim 39, further comprising compensating for the effects of any unwanted voltage components.

41. A means for determining the local concentration distribution of a conducting continuous phase of a multiphase fluid using an impedance cross correlation technique comprising:

a flow tube through which the multiphase fluid may flow;

a first array of electrodes arranged uniformly around the circumference of the flow tube;

a second array of electrodes arranged uniformly around the circumference of

the flow tube and axially separated from the first array by a predetermined distance;

means for applying a sequence of electrical potentials to the electrodes of the second array so as to generate an electrode potential rotational pattern;

means for measuring the resistance of the multiphase fluid in a predetermined region of the flow cross section;

means for determining the conductivity of the multiphase fluid using the resistance of the multiphase fluid; and

means for determining the local concentration distribution of the conducting continuous phase using the conductivity of the multiphase fluid.

42. A means for determining the mean density of a multiphase fluid comprising:

a flow tube through which the multiphase fluid may flow;

means for determining a differential pressure in the multiphase fluid by measuring the pressure of the multiphase fluid at different points along the length of the flow tube;

means for determining the mean fluid density of the multiphase fluid using the measured differential pressure.

43-46. -46. (canceled)