Population balance modeling of unstirred cooling crystallization on an integrated belt filter

Abstract

The successive unit operations of cooling crystallization, cake filtration and contact drying are joined in one apparatus, the modular integrated belt filter, for small-scale downstream processing. This modular equipment offers high flexibility without external solid transport. After prior studies on equipment setup and functionality, this contribution focuses on understanding and influencing unstirred cooling crystallization in small layers with the aid of population balance modeling.An unstirred cooling crystallization is dominated by sedimentation effects. Thus, particle size distributions (PSD) are modeled for discrete spatial compartments based on orthogonal collocation on finite elements. Model validation regarding temperature profile and yield is conducted for two material systems featuring high (sucrose/water) and low viscosity (ascorbic acid/water). With a high impact on sedimentation, viscosity influences product quantity (yield) and quality (PSD). For both material systems, the effects of operating parameters on yield and PSD are determined through a parameter study based on surrogate models to derive optimal operating conditions.