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. These results are also supported by rigorous simulation and optimization.

Optimization of cooling strategy and seeding by FBRM analysis of batch crystallization

“…According to Wang and Ward's conclusion [1,11], the trajectory that has the constant supersaturation could minimizes the number of nuclei in the case of nucleation was independent of the crystal mass. The result of the optimized cooling curve was consistent with this conclusion because Fig .1 showed that the nucleation rate was relatively independent with the crystal mass.…”

“…Optimized seed loading policy is a helpful guideline for process design [1]. When gmax was known, the optimized seed loading policy could also be developed.…”

“…For optimizing a seeded batch crystallization, generally, it could be divided into two main parts: first, determination of the optimal temperature trajectory; second, optimizing the seed loading policy [1]. Various excellent approaches have been proposed for designing the temperature trajectory or seed loading policy [2][3][4][5][6][7].…”

“…Kubota and coworkers developed the critical seed loading that is the lowest seed loading ratio for which all of the material crystallizes out of the solution is consumed by the growth of the seeds [20,21]. Yu-Ti Tseng and Jeffrey D. Ward developed a shortcut approach to determine the seed loading chart and Hsing-Yu Wang and Jeffrey D. Ward applied this approach in the reactive crystallization of barium sulfate and L-glutamic [1,21].…”

Seed Recipe Design for Batch Cooling Crystallization with Application to l-Glutamic Acid

“…It was recognized that seeding has an impact on the product yield and purity, crystal morphology, and crystal size distribution (CSD), which in turn affect the downstream operations such as filtration, drying, and packing of final products [3][4][5] . Seeded crystallization methods have been increasingly investigated in the past two decades 2,[6][7][8][9] . However, for optimization of seeded cooling crystallization processes, the existing literature (see e.g.…”