CFD Modeling of Semi-Batch Reactive Crystallization in a Stirred Tank with Subsurface Feeding

Reactive crystallization processes are widely used in the industrial production of chemical products such as pharmaceutical compounds. In a typical setup, an acid solution is injected into a sitting base solution in a stirred tank reactor through a feeding tube extending below the liquid interface. Reaction between these components generate an insoluble salt that crystallizes and precipitates as solid particles. We are interested in the fast reaction limit where the reaction and nucleation time scales are much shorter than the macro-mixing time. As such, crystal formation and particle size distribution are highly sensitive to mixing and flow conditions. CFD models are developed which couples multiphase flow models with species transport and population balances to predict the mixing flow patterns and particle size distribution under different operating conditions. Effects of process design and operating parameters on the mixing performance and particle size control will be discussed.