A MODEL OF CRYSTALLIZATION IN AN IMPERFECT SUSPENSION CRYSTALLIZER

摘要

Crystallization kinetics is commonly measured using the MSMPR crystallizer technique [1]. This technique permits simultaneous determination of both growth and nucleation rates by analysis of the crystal size distribution at a given mean residence time during steady-state operation. Imperfect suspension crystallizer do not fulfill the criteria used as basic assumptions for the modelling of MSMPR crystallizers. Generally, the data measured by non-MSMPR are of little value when determining crystallization kinetics. However, imperfect suspension crystallizer is widely found in industrial crystallizers and it can also be encountered in large scale laboratory crystallizers [2]. How can the crystal size distribution be predicted and how do the crystallization kinetics change when an imperfect suspension crystallizer is used? This is an important question for evaluating the crystallization process and scale-up of the crystallizer. Based on suspension density distribution and local particle size distribution in the crystallizer, a model which can be used to estimate the crystallization kinetics in a non-MSMPR crystallizer has been developed by defining a function g[Z, f(L,D),L] or h[Z, f(L,D),L]. This model can be used to predict particle size distribution both in the product and in the crystallizer. The crystal growth rate can be estimated even though non-MSMPR operation is used. In this model, the effect of mixing intensity and product removal location on the particle size distribution have been taken into account.