A capacitance sensor with hydrocyclone phase separator for measuring water volume fraction in gas-liquid two-phase flow

doi:10.11949/j.issn.0438-1157.20170510

Abstract

Abstract:

In order to improve capability of electric capacitor for liquid volume fraction measurement, a capacitive liquid volume fraction sensor with a hydrocyclone phase separator was designed for measurement of water fraction in gas-liquid two phase flow. The hydrocyclone phase separator, which was added to the measuring section of a capacitance sensor, was optimized in structure according to kinetic theory of gas liquid two-phase flow and was determined for the number of separation cycles by actual application conditions to ensure efficiency of gas liquid phase separation. The hydrocyclone phase separation could overcome influence of various flow patterns of gas liquid two-phase flow, and convert water volume fraction information into liquid film thickness cross-section water fraction information measurement. The experimental results show that cross-section gas fraction measured by the capacitance sensor is in good agreement with the Lockhart-Martinelli cross section gas fraction model. The gas liquid two-phase flow with water volume fraction below 20% can be effectively measured with less than ±2% absolute error.

Key words: water volume fraction, measurement, capacitance sensor, hydrocyclone phase separation, gas holdup, gas-liquid flow, fluid mechanics

摘要：

为提高电容器对含水率测量的能力，设计与其相匹配的旋转分相单元，以实现气液两相流含水率的起旋分相式电容测量。在电容传感器的测量单元基础上，增加旋转分相单元，利用气液两相流体力学理论对其结构进行设计优化，并根据实际应用条件确定分离圈数，保证气液分相效率。旋转分相单元克服了气液两相流流动形态的多样性，将体积含水率信息转换成液膜厚度信息及截面含水率信息进行测量。经实验验证，Lockhart-Martinelli截面含气率模型与实验中电容器测量截面含气率具有良好的一致性，其能够实现对体积含水率20%以内的气液两相流有效测量，体积含水率的绝对误差在±2%以内。

关键词: 体积含水率, 测量, 电容传感器, 旋转分相, 气含率, 气液两相流, 流体力学

CLC Number:

O359⁺.1

XU Ying, XIE Fei, LI Jian, ZHANG Tao, LI Tao, MI Baotong. A capacitance sensor with hydrocyclone phase separator for measuring water volume fraction in gas-liquid two-phase flow[J]. CIESC Journal, 2018, 69(4): 1357-1364.

徐英, 谢飞, 李建, 张涛, 李涛, 米宝桐. 基于旋转分相单元的电容式气液两相流含液率测量[J]. 化工学报, 2018, 69(4): 1357-1364.

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