5. Conclusions
A novel MACC technology was developed and comprehensively investigated
to realize the automatic and accurate control of thiourea cooling
crystallization, which governed by the heterogeneous nucleation and
automatic screening on the PTFE and PES hollow fiber membrane
interfaces. With effective interfacial heat transfer, the mechanism of
membrane interface induced nucleation and process control was fully
validated via the nucleation research and on-line monitoring. The
overwhelming performance of MAAC reflects as dominating the accurate
nucleation kinetic and hindering the secondary nucleation effectively,
which resulting in the high purity, desire product morphology and very
narrow CSD compared to that of conventional cooling crystallization
(both artificial seeding and spontaneous nucleation operations were
compared). Space-time process decoupling via surface nucleation in the
membrane module and crystal growth in crystallizer, which is the core
feature of the developed MACC, is a novel path for accurate
crystallization control and process intensification.