Single phase flow measurement

• US 4,347,747 A
• Filed: 01/12/1981
• Issued: 09/07/1982
• Est. Priority Date: 01/12/1981
• Status: Expired due to Term

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Krishnaswamy, Srinivasan
• Primary Examiner(s): Ruehl, Charles A.
• Application Number:
  US06/224,409
• Time in Patent Office: 603 Days
• Field of Search: 73/861.04, 73/861.18, 73/861.21, 73/861.22, 73/861.32, 73/861.34, 73/861.42, 73/155, 340/611
• US Class Current: 73/861.18
• CPC Class Codes: G01F 1/32 using swirl flowmeters
• CPC Class Codes: G01F 1/3259 for detecting fluid pressure oscillations

Abstract

A method and apparatus for measuring fluid flow by placing two pressure sensors diametrically opposite each other in a flow line. The use of two sensors effectively cancels acoustic pressure fluctuations while preserving the local turbulent pressure fluctuations. The turbulent pressure fluctuations are proportional to the square of the flow rate of the fluid and are processed by the electrical circuit to derive a quantity proportional to the fluid flow rate.

Claims

1. A method for measuring single phase fluid flow rate in a pipe comprising:

measuring the fluid pressure fluctuations in the pipe at two diametrically opposite positions;

taking the different of said measured pressure fluctuations;

electronically filtering said different to pass only signals above 30 Hz and below 1000 Hz;

taking the RMS value of the filtered difference in said measured pressure fluctuations; and

,

taking the square root of the RMS signal, said square root being proportional to the fluid flow rate.

2. An apparatus for measuring fluid flow in a pipe comprising:

two pressure transducers, said transducers being mounted on said pipe with their sensitive surfaces flush with the inner surface of the pipe;

differential amplifier means, said transducers being coupled to said differential amplifier means to obtain a difference signal;

filter means, said filter means being coupled to said differential amplifier means to attenuate frequencies below 30 Hz and above 1000 Hz;

RMS circuit means coupled to said filter means for obtaining the RMS value of the different signal; and

,

a square root circuit, said RMS circuit means being coupled to said square root circuit means to obtain the square root of the RMS signal.

3. The apparatus of claim 2 and in addition a notch filter for removing 60 Hz signals from said different signal.