A Procedure for Design of Crystallization Processes of Multi-Component Electrolyte Systems

Fractional crystallization is a commonly used separation technique for downstream processing of reactor effluent in chemical and biochemical processes. In this work a procedure for design of crystallization processes of multi-component system is described. The procedure consists of three parts; generation of phase diagram, generation of all feasible flowsheet alternatives, and the screening part. As an example, the ionic system of (Na+, K+; Cl-, SO4 -2; H2O) is considered. This ionic system is related to the process, which is used for the production of K2SO4 and NaCl from Na2SO4 and KCl. The activity coefficients of ions in this system are calculated by the UNIQUAC model. Using these values of activity coefficients in the equilibrium equations, the phase diagrams (thermodynamic part) of the system are generated. These phase diagrams are used to generate a flowsheet for production K2SO4 from KCl and Na2SO4.

Keywords:

fractional crystallization , UNIQUAC model , multi-component solutions