Compartmental modeling of an 1100L DTB crystallizer based on Large Eddy flow simulation

Publisher Summary Evaporative crystallization is used in industry for the manufacturing of both bulk solid products (e.g. fertilizers and sugar) and fine chemicals. The hydrodynamic conditions in the crystallizer play an important role in the performance and behavior of the crystallization process. The flow patterns in the equipment determine the crystal residence time in various sections of the crystallizer, while the turbulence characteristics are of influence on the mass transfer from the mother liquor to the crystal surface. In addition to this, crystal-impeller impacts can cause breakage and is therefore important for effects like secondary nucleation. All these effects influence product properties (e.g. crystal size distribution) and process behavior. This chapter focuses on the development of a compartmental model for the dynamic simulation of an ll00L DTB crystallizer. Design of the compartment structure is based on high resolution computational fluid dynamics (CFD) simulation of the internal flow of the crystallizer. The CFD simulation of the turbulent flow field is based on a lattice-Boltzmann scheme with a Smagorinsky subgrid-scale turbulence model (cs was 0.11). The fully developed turbulent flow field was simulated at Re=240.000 on 35.5.106 grid nodes. A detailed compartmental model with 21 compartments is derived. The model contains mass, heat and population balances for each compartment. From the CFD simulations, flow rates and local rates of energy dissipation for each compartment are determined. Explorative simulation results of the compartmental model are presented to demonstrate the influence of compartment structure, short circuiting flow and rate of energy dissipation on the evolving crystal size distribution.