Mathematical Modelling and Simulation of Recirculatory Flow as well as Mixing Phenomena in Gas Stirred Liquid Baths

Abstract

A numerical scheme has been proposed to describe the mixing phenomena in a gas stirred liquid bath. The liquid recirculation flow rate has been estimated by combining a macroscopic, steady state energy balance model and an empirical correlation to take care of the swirling motion of the plume. The numerical scheme combines the concepts of mixing with the recirculation flow within a series of well stirred reactors arranged in a closed loop. The number of reactors (M) that are to be in the annular zone and the residence time (Δt) of circulating liquid in each reactor have been found to be dependent on each other. For a given values of M, there seems to be a constant value of Δt and vice versa. Keeping Δt constant, the value of M has been found to be a function of bath height and almost independent of other operating variables. The predicted values of mixing time have been compared with the reported experimentally measured values. Circulation number has been estimated using the predicted mixing time and circulation time values. It has been shown that the model is useful in estimating mixing time values for the industrial vessels.