A gas-liquid two-phase flow phase holdup real-time capacitance measurement system and its measurement method

Abstract

The invention discloses a real-time capacitance measurement system for a phase volume fraction of gas-liquid two-phase flow and a measurement method thereof. The real-time capacitance measurement system comprises a double-concave-surface capacitance electrode device consisting of a double-concave-surface capacitance electrode group mounted on the outer wall of an insulating pipeline, an insulating filling material and a copper protection shell, a signal source and capacitance-voltage conversion integrated circuit, an acquisition board card and a computer, wherein the signal source and capacitance-voltage conversion integrated circuit comprises an MS3110 chip, an INPUT CAP, a USB (universal serial bus) interface, a single-chip microcomputer, a Vout air interface and a restarting key. The measurement method comprises the steps of setting a chip parameter; performing static gas-liquid two-phase flow calibration through the double-concave-surface capacitance electrode device, assembling a double-concave-surface capacitance electrode on the outer wall of a pipeline to be measured, and performing phase volume fraction measurement on the gas-liquid two-phase flow moving in the pipeline. According to the real-time capacitance measurement system, the radial length of the pipeline is large, and the real-time capacitance measurement system is sensitive to the micro change of the phase volume fraction on the inner section of the pipeline; a difference of output voltage values is enabled to be outstanding by changing a built-in parameter of the chip.

Description

technical field [0001] The invention relates to a gas-liquid two-phase flow phase holdup real-time capacitance measurement system and its measurement method. The two-phase flow phase holdup is measured by a double-concave capacitance electrode for volume measurement, and is mainly used in gas-liquid stratified flow and bubbly flow. The invention relates to phase holdup measurement of flow patterns such as slug flow, and belongs to the technical field of multiphase flow transportation. Background technique [0002] In the fields of modern oil extraction and transportation and nuclear power generation, the phase holdup measurement of gas-liquid two-phase flow is a very important subject. Accurate calculation of parameters such as interface phase distribution and flow pattern change provides a basis for calculation of pressure drop along the pipeline. [0003] At present, there are many methods for measuring holdup of gas-liquid two-phase flow, such as optical method, ray meth...

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Problems solved by technology

However, this method is also affected by the trailing vortex of the probe, and the single-wire capacitive probe installed inside the pipeline does not shield the stray capacitance on the pipeline, and the measurement of phase holdup is limited to the gas-liquid phase. Evenly distributed flow pattern, unable to measure phase holdup of unevenly distributed two-phase flow

Another example is the Chinese patent application text "a small pipeline gas-liquid two-phase flow porosity measurement spiral capacitive sensor" (disclosure date October 20, 2010, publication number CN101865872A, application date April 27, 2010) discloses a The micropipeline gas-liquid two-phase flow void ratio measurement spiral capacitive sensor can measure the phase holdup in the gas-liquid two-phase flow, and is not affected by the electrode edge effect and flow pattern change, but the pipe diameter measured by this system is relatively small. Small, high processing requirements for the spiral electrode, the ratio of the pitch to the pipe diameter is relatively large, and it is difficult to measure the change of phase holdup in the cross-section of the large-diameter pipe

[0005] To sum up, there are some limitations in the current measurement methods of phase holdup. For the phase holdup of pipeline cross-section, the measurement section is incomplete or the length of the pipeline is large, and the accurate change law of phase holdup cannot be given, so it is difficult to Realize high-precision real-time measurement of phase holdup in the pipe

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