摘要
Simultaneous population and mass balance equations were solved together with power law kinetics of nucleation and growth rate in computer Programs RECYC and SMUG to predict the crystal-size distribution from a multistage classified recycle crystallization process. Transformation from nonhomogeneous ordinary differential equations to moment equations made it convenient to model many complex configurations and resulted in a significant saving of computer time. The population distribution of the last stage was assumed to be a distribution in these calculations. This critical assumption not only provides enough data to calculate recycle moments but also avoids the numerical errors inherent in other techniques for the inversion of moments to obtain CSD. The effects on CSD of the form of the classification function were studied for hypothetical self-nucleating alumina and externally seeded sugar processes. For the alumina process, the recycling of a large fraction of classified particles increases the yield and mean particle size and narrows the CSD. For the sugar process, mean size is determined by external seed rate. Again, the distribution is narrowed with increasing recycle of classified crystals. Production rate increases when recycling more undersize particles due to the increase in specific surface area. The phenomenon of size dispersion due to growth rate fluctuations limits the ultimate narrowness of CSD that can be obtained in a staged classified recycle sugar crystallizer. © 1978, American Chemical Society. All rights reserved.