Examination of the Process Scale Dependence of l-Glutamic Acid Batch Crystallized from Supersaturated Aqueous Solutions in Relation to Reactor Hydrodynamics

Abstract

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.

A new interpretation of metastable zone widths measured for unseeded solutions

“…Therefore, it has been used long for kinetic studies of nucleation. The Nyvlt's equation [2] is well known for the kinetic studies and has been used widely until recently [3]. However, there are some criticisms to this equation.…”

Crystallisation Route Map

“…Liang et al [28,45] investigated the effects of reactor internals [28] and reactant mixing [45] on the measured MSZW associated with the batch crystallisation of L-glutamic acid from supersaturated aqueous solutions. The cooling crystallisation experiments were 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.…”

“…The comparisons of power number, discharge flow number, secondary circulation flow number and pumping efficiency at three different scales suggest that the scale up with the selected laboratory vessels has little effect on the macro mixing performance for optimisation of the configuration and operating conditions of an industrial scale reactor. Further details about the experimental and modelling investigations of process scale-up can be found in the literature, such as [28,32,[45][46][47][48][49].…”

Multi-scale segmentation image analysis for the in-process monitoring of particle shape with batch crystallisers

“…It is known that minor changes in supersaturation, cooling rates, reactor hydrodynamics, pH and impurity in the feed can have significant impact on the crystal product. In addition, there are unexpected factors which can become deterministic, such as wall effects on heat transfer, baffles, and impeller materials and types (Liang, 2002). For these reasons, there is a genuine need to develop on-line techniques for real-time measurement of crystal morphology from nucleation through crystal growth until completion of a batch run.…”