Gas–liquid two-phase flow measurement using ESM

Abstract

A new method for gas–liquid two-phase flow measurements––the extracting and separating method was proposed and tested in an air–water two-phase flow loop. By using a rotational drum distributor, a fraction (about 20%) of the total flow is proportionally extracted continuously and directed to a small compacted separator which separate the mixture into single phase gas and liquid. Single-phase flow meters are provided to measure the separated gas and liquid respectively, and then these measured values are converted to the total flow rate of each phase according to the proportionality (extraction ratio). After the separated gas and liquid have been metered they are returned to the main stream again. Because only a small portion of the total flow is extracted the separator can be reduced in size greatly compared to the conventional separation method. Theoretical and experimental results confirmed that the extraction ratio was equal to the ratio of the extraction channel number to the total channel number inside the drum and independent of flow patterns. The average error of flow rates measurement was about 5%. The inner diameter of the test section was 30 mm and the test section was horizontally placed. Flow patterns occurring during the tests included stratified flow, wave flow and annular flow.