AN ELECTRICAL RESISTANCE TOMOGRAPHIC STUDY OF GAS­ LIQUID MASS TRANSFER IN A CONTINUOUS STIRRED TANK REACTOR

Bawadi Abdullah, Chirag B. Dave, Tuan­Huy Nguyen, Cyrus G. Cooper and Adesoji A. Adesina*

Reactor Engineering & Technology Group, School of Chemical Engineering The University of New South Wales, Sydney, New South Wales, Australia 2052

*Corresponding Author: Tel.: +61293855268; Fax: +61293855966 E­mail: a.adesina@unsw.edu.au

Abstract

A gas­entrainment impeller is attractive for multiphase reactive systems such as Fischer­Tropsch reaction and deep liquid­phase oxidation of organics with the possibility of low gas conversion per pass, enhancement of mixing performance and better inter­phase mass transfer compared to conventional impellers. Three different types of gas­liquid mixing were investigated. Tomograms obtained from ERT measurement reveal that the conductivity of gas­water system changes as a function of impeller Reynolds number, ReI. The global gas holdup profile behaviour with ReI exhibited a sigmoid character. The radial gas holdup profiles showed an upward parabolic trend with higher gas holdup values for gas­ entrainment impeller systems than the conventional 4­blade impeller. To assess the efficiency of power consumption, the mass transfer coefficient, kLa, for gas­liquid system in stirred tank reactor was correlated as a function of dimensionless combination of power number and gas holdup;

Keywords: gas holdup; mass transfer coefficient; CSTR; ERT.