CFD-population balance modelling for a flat sheet membrane-assisted antisolvent crystallization

A comprehensive model has been developed to couple CFD with the population balance equation (PBE) for a flat sheet membrane-assisted antisolvent crystallization (FS-MAAC) process. The model accurately depicts the fluid dynamics, mass transfer, heat transfer and crystal size distribution (CSD) in the FS-MAAC crystallizer. The crystallization system considered was to produce α-form crystals of glycine. The model investigates the effects of different parameters, such as the velocities of the crystallizing and antisolvent solutions, antisolvent composition, temperature, and gravity. A good agreement was observed between the simulation results and experimental data for the α-form crystals of glycine. The simulation results show a steady-state antisolvent concentration profile in the liquid layer and varied only in the z-direction. Regardless of the variations in the velocity of either the antisolvent solution or the crystallizing solution, the CSD remained narrow, with mean crystal sizes ranging from 27 to 40 μm. Furthermore, increasing mass transfer through the antisolvent transmembrane flux leads to a narrower CSD. Slower antisolvent permeation rates at higher temperatures also promote crystal growth. Also, a narrow CSD is maintained regardless of the initial circulation position of the antisolvent solution. In conclusion, membrane antisolvent crystallization provides a reliable and consistent solution for obtaining crystals with desired CSD under optimal operating conditions.