Application of Ultrasonic Technique in Multiphase Flows

Ultrasonic technique was used as a tool for phase holdup measurement in multiphase systems. A new statistical approach using fluctuations of the ultrasound signals was applied to simultaneously detect the dispersed phase holdups in gas−liquid−solid flows. These phase holdups, measured by two methodsthe ultrasonic technique and the applications of pressure transducers and conductivity probesagreed well. In the system of a high liquid velocity (above 14 cm/s), the ultrasonic technique still provided reliable results. The local phase holdups and their radial distribution were measured in gas−liquid−solid three-phase circulating fluidized beds at two different elevations. A nonuniform radial distribution and a uniform axial distribution of gas and solid phases were observed. The nonuniform radial distribution of solid holdup did not depend on the solid circulating rate. The radial distributions of both phase holdups became uniform with increasing liquid velocity.