Method and system for analyzing a two phase flow

• US 5,714,691 A
• Filed: 10/24/1996
• Issued: 02/03/1998
• Est. Priority Date: 11/02/1994
• Status: Expired due to Term

• Current Assignee: Foster-Miller Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Foster-Miller Incorporated (Thermo Fisher Scientific Incorporated)
• Inventors: Hill, Wayne S.
• Primary Examiner(s): Biegel, Ronald L.
• Assistant Examiner(s): THOMPSON, JEWEL VERGIE
• Application Number:
  US08/736,523
• Time in Patent Office: 467 Days
• Field of Search: 73/861.04, 73/29.01, 73/659, 73/30.03, 73/23.2, 73/24.01, 73/24.04
• US Class Current: 73/861.04
• CPC Class Codes: G01B 5/28 for measuring roughness or irregularity of surfaces
• CPC Class Codes: G01F 1/002 wherein the flow is in an open channel
• CPC Class Codes: G01F 1/666 by detecting noise and sounds generated by the flowing fluid
• CPC Class Codes: G01F 1/667 Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
• 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
• CPC Class Codes: G01N 2291/02818 Density, viscosity
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/2425 optoacoustic fluid cells therefor
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency
• CPC Class Codes: G01N 29/4481 Neural networks
• CPC Class Codes: G01N 29/48 by amplitude comparison
• CPC Class Codes: G06V 20/64 Three-dimensional objects

Abstract

A method of and system for analyzing a two-phase flow in a conduit in which acoustic energy is transmitted through a conduit and into the flow therein; return echoes are detected, one or more flow indicator quantities are computed from the return echoes; and the mass flow rate and/or the flow quality is determined from the computed flow indicator quantities.

Claims

1. A method of determining the quality of a two-phase flow in a conduit, comprising:

transmitting acoustic energy through the conduit wall and into the flow therein to generate from the flow return echoes;

detecting the return echoes from the flow;

computing the two-phase flow mass flow rate; and

determining from the return echoes at least one of the mass flow rate and the flow quality.

2. The flow quality determination method of claim 1 in which transmitting acoustic energy includes providing ultrasonic pulses to the outer conduit wall.

3. The flow quality determination method of claim 1 in which detecting return echoes includes determining the fraction of echoes above a predetermined echo strength.

4. The flow quality determination method of claim 3 in which determining the mass flow rate includes resolving the two-phase flow rate from the fraction of return echoes above the predetermined echo strength.

5. The flow quality determination method of claim 1 in which determining the flow quality includes calculating the liquid film thickness on the conduit from the return echoes.

6. The flow quality determination method of claim 5 in which determining the flow quality further includes calculating the average change in calculated liquid film thickness.

7. The flow quality determination method of claim 6 in which determining the flow quality further includes determining the average calculated film thickness.

8. The flow quality determination method of claim 7 in which determining the flow quality further includes determining the ratio of the average change to the average film thickness.

9. The flow quality determination method of claim 1 in which determining flow quality includes calculating one or more flow indicator quantities from the detected return echoes from the flow.

10. The flow quality determination method of claim 9 in which said flow indicator quantities include one or more of:

the average number of good thickness readings, the average change in sequential good readings, and the average fraction of the total readings that are good readings, wherein a good reading is defined as a detected return echo, assumed indicative of the thickness of liquid flow in the conduit.

11. The flow quality determination method of claim 10 further including calculating the quantity of the average absolute value change in sequential good readings divided by the average number of good readings for discriminating between mass flow and quality.

12. The flow quality determination method of claim 10 in which said flow indicator quantities further include the RMS of good thickness readings, the RMS change in sequential good readings, the average number of good readings in a row, the average number of bad readings in a row, and the characteristic autocorrelation time.

13. The flow quality determination method of claim 1 in which determining the mass flow rate and the flow quality further includes applying one or more of said flow indicator quantities to a neural network for matching said flow indicator quantities with known flow conditions.

14. A system for determining the quality of a two-phase flow in a conduit, comprising:

means for transmitting acoustic energy through the conduit wall and into the flow therein to generate from the flow return echoes;

means for detecting the return echoes from the flow; and

means for computing the two-phase flow mass flow rate; and

means for determining from the return echoes at least one of the mass flow rate and the flow quality.

15. The system of claim 14 in which said means for transmitting acoustic energy includes providing ultrasonic pulses to the outer conduit wall.

16. The system claim 14 in which said means for detecting return echoes includes determining the fraction of echoes above a predetermined echo strength.

17. The system of claim 16 in which said means for computing the mass flow rate includes means for resolving the two-phase flow rate from the fraction of return echoes above the predetermined echo strength.

18. The system of claim 14 in which said means for determining includes means for calculating the liquid film thickness on the conduit from the return echoes.

19. The system of claim 18 in which said means for determining further includes means for calculating the average change in calculated liquid film thickness.

20. The system claim 19 in which said means for determining further includes means for calculating the average calculated film thickness.

21. The system of claim 20 in which said means for determining further includes means for calculating the ratio of the average change to the average film thickness.

22. The system claim 14 in which said means for determining includes means for calculating one or more flow indicator quantities from the return echoes.

23. The system of claim 22 in which said flow indicator quantities include one or more of the average number of good thickness readings, the average change in sequential good readings, and the average fraction of the total readings that are good readings, wherein a good reading is defined as a detected return echo, assumed indicative of the thickness of liquid flow in the conduit.

24. The system of claim 22 further including calculating the quantity of the average absolute value change in sequential good readings divided by the average number of good readings for discriminating between mass flow and quality.

25. The system of method of claim 23 in which said flow indicator quantities further include the RMS of good thickness readings, the RMS change in sequential good readings, the average number of good readings in a row, the average number of bad readings in a row, and the characteristic autocorrelation time.

26. The system of claim 14 in which said means for determining the flow quality further includes a neural network for matching said flow indicator quantities with known flow conditions.

27. A method for determining the mass flow rate and quality of a two-phase flow in a conduit, comprising:

transmitting acoustic energy through the conduit wall and into the flow therein to generate from the flow return echoes;

detecting the quantity of return echoes above a predetermined echo strength;

determining from the quantity of return echoes the two-phase flow mass flow rate;

calculating from the return echoes the liquid film thickness on the conduit wall; and

determining the average change in calculated liquid film thickness, the average calculated film thickness, and the flow quality from the ratio of the average change to the average film thickness.