Hydrodynamics and volumetric gas–liquid mass transfer coefficient of a stirred vessel equipped with a gas-inducing impeller

Abstract

Hydrodynamic and mass transfer characteristics of a gas–liquid stirred tank provided with a radial gas-inducing turbine were studied. The effect of the rotation speed and the liquid submergence on global hydrodynamic and mass transfer parameters such as the critical impeller speed, the induced gas flow rate, the gas holdup, the power consumption and the volumetric gas–liquid mass transfer coefficient were investigated. The experiments are mainly conducted with air–water system. In the case of critical impeller speed determination, two liquid viscosities have been used. The volumetric gas–liquid mass transfer coefficient k L a has been obtained by two different techniques. The gas holdup, the induced gas rate and the volumetric gas–liquid mass transfer coefficient are increasing functions with the rotation speed and decreasing ones with the liquid submergence. The effects of these operating parameters on the measured global parameters have been taken into account by introducing the dimensionless modified Froude number and correlations have been proposed for this type of impeller.