Research and application of solution crystallization thermodynamics and process analysis

Crystallization is an important means of separation and purification. Many products in the fields of medicine, food, fertilizer and so on are in the form of crystals. Thermodynamics is the theoretical basis of the study of the crystallization process. The thermodynamic properties of the target system have an important influence on the selection of crystallization methods (cooling crystallization, evaporative crystallization, anti-solvent crystallization, etc. ), while the thermodynamic equilibrium relationship determines the limit of crystallization yield and the stability of different crystal forms under specific conditions. Therefore, the research of thermodynamics has important guiding significance for the optimization and amplification design of the crystallization process. In this paper, the measuring methods of solid-liquid equilibrium data of different crystallization systems were summarized; and several thermodynamic modelling cases of phase equilibrium using models such as NRTL, e-NRTL and MSE were shown; the methods of measurement and calculation of supersaturation, and metastable region and phase diagram in crystallization process optimization and selection of separation methods was introduced; in addition, the application status of process analysis technology in the field of solution crystallization was summarized,and its development tendency in crystallization field was prospected.