Seeding and Optimization of Batch Reactive Crystallization

Abstract

Conceptual methods are illustrated for the development of operating policies for batch reactive crystallization processes. Two processes, production of barium sulfate and production of l-glutamic acid, are studied. For barium sulfate, the critical seed loading ratio is found to be above the practical limit, which suggests that seeding cannot be employed to suppress nucleation. Conversely, for l-glutamic acid, the critical seed loading ratio is below the practical limit for a wide range of seed sizes, suggesting that seeding can be used to suppress nucleation almost entirely. These results are verified by rigorous process simulation. Furthermore, for the barium sulfate process, a plot of nucleation rate B versus growth rate G is concave, indicating that an early growth trajectory (with supersaturation highest at the beginning of the batch) will minimize the nucleated mass, while for the l-glutamic acid process the plot is convex, indicating that a late growth trajectory will minimize the nucleated mass. Th...