Effect of baffle configuration on performance of batch stirred vessel

Abstract

Crystallization is often carried out in batch stirred vessels. However, it is difficult to obtain uniform crystal size distribution (CSD), as it strongly depends on prevailing flow field operating conditions. This is adversely affected by the geometry of stirred vessels. Hence in this work, CFD simulations were performed to investigate flow field, mixing and crystallization phenomena in a stirred vessel. The performance of the stirred vessel was compared with draft tube baffled stirred vessel. The flow field was quantified through liquid circulation and vorticity. The mixing was analyzed through macromixing time in the stirred vessel. The solubility data, nucleation, and growth kinetics were integrated with CFD through a user-defined function (UDF) to predict crystallization phenomena. The predicted results were validated with experimental data available in the literature. The effects of seed mass, size and temperature on CSD were investigated and optimum conditions [750 gm (seed mass); 500 µm (seed size); 308 K (temperature)] for favourable crystal growth were identified. The performance of the proposed baffled stirred vessel was found to be significant, and it supports enhancing flow field, mixing and crystallization process. © 2022, The Korean Institute of Chemical Engineers.