Investigation of Crystallization in a Jet Y-Mixer by a Hybrid Computational Fluid Dynamics and Process Simulation Approach

Abstract

A hybrid approach incorporating a computational fluid dynamics (CFD) package and process simulation tool was employed to simulate the steady-state crystallization of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in a Y-mixer crystallizer. Mixing effect was intensively investigated through the three-dimensional spatial distributions of velocity, supersaturation, kinetic rates, mean crystal size, coefficient of variation, and yield. The hybrid approach could predict the literature experimental data on mean crystal size, coefficient of variation, and production rate at the exit of the outlet tube reasonably by adjusting three factors (K, Ehet, and f) for nucleation and crystal growth that are difficult to determine by experiment or theory. It was found that even in a small-scale Y-mixer crystallizer a mixing effect was evident and that nuclei were generated dominantly by primary homogeneous nucleation and were grown at the rate controlled by both bulk diffusion and surface integration for the experimental supersaturation range.