Automated direct nucleation control for in situ dynamic fines removal in batch cooling crystallization

Abstract

Secondary nucleation (e.g. due to attrition) and accidental seeding (e.g. from crust on the wall of vessels) are undesired events that often take place during industrial crystallization processes. The crystal size distribution is greatly affected by these events. The typically used open loop control strategies fail to respond to these dynamic changes resulting in undesired end product properties. Variations in seed quality during seeded operations (e.g. initial breeding) can also result in undesired product quality. The automated direct nucleation control (ADNC) approach presented in this paper automatically detects any changes in the system and removes fines in situ. The approach is tested for external seed additions and accidental seeding scenarios. The results show that the ADNC approach is able to detect any changes in the metastable zone width and drive the system accordingly to dissolve unwanted fines providing an automatic in situ fines removal mechanism.