Design of Continuous Crystallizer with Fines Removal for Melt Crystallization of Caprolactam

Abstract

A method of designing a new type continuous crystallizer with fines removal for the suspension melt crystallization of caprolactam is presented. The crystallizer enables one to obtain crystals with a relatively large average size. An algorithm has been developed on the basis of the experimental data obtained from a specially designed crystallizer for suspension melt crystallization. The algorithm is based on a mathematical model of CSD and on derived balance equations and exploits the geometrical similarity between the laboratory crystallizer and its industrial version. The algorithm can be used to calculate: a) the cumulative mass size distribution of the caprolactam crystals in the obtained product, b) median crystal size L₅₀, c) the mass streams in the crystallizer installation and their concentrations and temperatures, d) crystallizer sizes. It can be also used to simulate the effect of fines removal on the size of the produced caprolactam crystals and on the crystallizer sizes.