Gas Holdup Measurement of Gas-water Flow Using Microwave Transmission Line Method

In natural gas industry, measurement on gas holdup of a gas-water flow with a wide range is of high interest. Based on the microwave transmission line method, this paper designs a microwave sensor for gas holdup measurement. The sensor contains two orthogonal transmission lines resulting in a spatial orthogonal combination structure, so that the gas-water flow regime can be detected and its influence on the measurement can be accounted for. The measurement system also employs a quick-closing valve calibration facility for the microwave sensor. Flow experiments, conducting on the gas superficial velocity within a range of 0 ~ 20 m/s, indicates that the sensor outputting normalized voltages are positive correlated to the gas holdup. A semi-empirical model of gas holdup is further developed based on the experimental data. The prediction results show that the relative error range is -9.09 ~ 13.96 %, and the absolute error range is -7.62 ~ 4.86 %, when the gas holdup is in range of 25 ~ 100 %.