Examination of the process scale dependence of L-glutamic acid batch crystallized from supersaturated aqueous solutions in relation to reactor hydrodynamics

The effects of reactor internals and reactant mixing on the measured metastable zone width (MSZW) associated with the batch crystallization of l-glutamic acid from supersaturated aqueous solutions are presented. The results of cooling crystallization experiments, as carried out at three reactor scales (450 mL, 2 L, and 20 L) agitated at various stirring speeds using an industry-standard retreat curve impeller with a single beaver-tail baffle, are shown. The observed MSZWs are mostly found to decrease with increasing stirring speed, with enhanced nucleation also being observed as the reactor scale increased; albeit hindered nucleation was found at higher stirrer speeds in the 450-mL reactor experiments. The MSZW data are correlated with Reynolds number to reveal a model reflecting the combined influences of hydrodynamics and scale on the overall nucleation process.