Gas-liquid mass transfer in vessels stirred with multiple impellers—II. Modelling of gas-liquid mass transfer

Abstract

In Part I of the article there were reported profound differences in behaviour between the bottom and the upper stages of a multiple-impeller vessel under gassed conditions: the volumetric mass transfer coefficient, k L a, for the bottom stage was by up to 50% lower than that for the upper stages. A procedure is presented that enables it to transfer k L a data from the basic single-impeller configuration to upper stages of the multiple-impeller vessel using correlations of power dissipated in individual stages of the reactor. The procedure is based on the idea of different amounts of aeration gas engaged in impeller regions of the bottom and upper stages. Further, an experimental way of modelling the upper stages by a single-impeller vessel with a spiral sparger placed on the bottom that distributes the gas uniformly through the whole tank cross-section is tested.