Application of Ultrasonic Technique in Multiphase Flows

Abstract

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 methodssthe ultrasonic technique and the applications of pressure transducers and conductivity probessagreed 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.

Hydrodynamics and Mass Transfer in Gas‐Liquid‐Solid Circulating Fluidized Beds

“…The transmitter and receiver, having a diameter of 13 mm, were mounted on the riser at two different axial positions. The detailed configuration and operation of this ultrasonic system are given elsewhere [8].…”

Application of acoustic techniques to fluid-particle systems – A review

“…The technique encounters problems in dispersed multiphase flows due to the scattering of the sound wave by the suspended particles or drops/bubbles. As a result, the wave can be significantly attenuated and may not be recorded by the receiving transducer (Vatanakul et al, (2004), DosRamos, ( 2012)).…”

“…Ultrasound has been used to analyse particle size distribution in multiphase flows for solids concentrations up to 60% (Nan et al, (2019), Patricia and Derek, (2000)) and a wide range of particle sizes, from 10 nm to 1 mm (Thao et al, (2016), Vatanakul et al, (2004)). Two types of waves have been applied: continuous and pulsed longitudinal waves (Atkinson and Wells, (1977)).…”

Process tomography of gas-liquid flow in a vessel: a review

“…A UT system in which the scatter in the transit time and in the signal amplitude increased as the gas volumetric concentration increased was studied by Zheng and Zhang (2004). The air bubbles in gas-liquid flow were said to have caused an increase in the acoustic wave transit time (Vatanakul et al, 2004). Murakawa et al (2008) applied Doppler method in a UT system to measure the velocity profiles of gas-liquid bubbly flows with a multi-wave ultrasonic sensor in a circular pipe.…”