Crystallization kinetics for the sugar-water-ethanol system in a continuous MSMPR crystallizer

The crystallization kinetics of sugar from aqueous and aqueous ethanol solutions in a continuous mixed-suspension mixed product removal (MSMPR) crystallizer are reported. Growth and nucleation rates are determined by the population balance analysis of crystal size distribution measured using laser light scattering. Findings show that in sugar-water system, there is a region of low supersaturation where no nucleation occurs. Seed crystals in this region grow, but do not spawn secondary nuclei upon crystal impeller or crysta-crystal contact. It is demonstrated that the level of supersaturation for nucleation decreases from 1.07 in a sugar-water system to 1.05 and 1.03 at ethanol concentrations of 15 and 30 kg ethanol/100kg water, respectively. The overall growth rate constant strongly decreases with increasing ethanol concentration in the crystallizing solution. The higher concentration of ethanol in the crystallizing solution, the larger the value of alpha-factor, that is a smoother surface. This implies that the growth rate can be reduced with ethanol.