Separation performance evaluation of green crystallization technique: Model configuration and process design

Layer melt crystallization (LMC) is deemed a green separation technique and is widely used in the purification of crude chemical products. This work optimizes the separation of LMC based on process design and model configurations. Firstly, we monitor the central temperature with the crystal layer growth, where the temperature change can be divided into two stages. The main heat exchange and crystal growth occur in stage 1. Then we establish two kinetics models based on the temperature and concentration difference, to describe the features of crystal layer growth. Both kinetic models can successfully correlate the driving force and kinetic parameters. Further, the temperature effect and composition of the feed mixture on the separation performance are analyzed. The proposed separation coefficients accurately figure out the underlying correlations of the technical variables and target products. The optimized operating trajectory based on the model analyses and experiments is given to guide the separation process. Finally, four process intensification strategies are proposed to improve separation efficiency, where the incorporation of the stirring operation into LMC is more suitable for industrial production.