APPLICATION OF MATHEMATICAL-MODELING IN A 2-COMPONENT LAYER CRYSTALLIZATION PROCESS

An algorithm for the computation of design variables in layer crystall isation processes is presented, based on an algebraic solution of the moving boundary equation for heat transfer, as well as on an expressio n for the concentration profile. The algorithm was applied to the disc ontinuous crystallisation of a NaCl-H2O solution around the wall of an internally cooled cylindrical tube. Good agreement between simulation results and laboratory experiments was observed. After input of exper imentally measurable values of the distribution coefficient, the algor ithm enables the prediction of the following process variables along t he crystallisation time: layer thickness, temperature, and composition profiles across the layer, as well as the end-values of solid and liq uid mass and concentrations. Multistage processes can be studied by th e series association of crystallisation cycles, enabling the determina tion of the optimal number of stages that meets a specific design crit erion.