Design of a multi-functional crystallizer for research purposes

The design procedure and the specifications for the design process and the resulting experimental set-up of a multi-functional 751 pilot plant crystallizer are described. The crystallizer can operate in different operational (batch/ continuous) and crystallization modes (cooling/flash-cooling/ evaporative). This flexibility enables the generation of experimental information on the relationship between process conditions and product quality for different model compound systems using one crystallizer. The design is realized using a hierarchical design procedure described previously, which is extended with an additional level for the design of instrumentation and control. The design procedure is useful to structure the design process of a pilot plant crystallizer and to identify design problems at an early stage. A description of the pilot plant crystallizer, a design synthesis model, a flowsheet design and an investment cost estimation of the experimental set-up and the cost of this infrastructure per typical experiment are presented. The designed pilot plant was actually built and successful crystallization experiments have been performed. However, the deviation seen between the median crystal sizes as specified as design target and the measured one in the realized crystallizer illustrates the need for a rigorous predictive crystallizer model to further analyse and optimize a design.