Ask Greg McMillan - What role do you see dynamic simulation playing in the future of best crystallizer temperature control?

Greg's Response:

Batch-operated stirred cooling crystallizers are the most common type in the industry, but they tend to yield poor quality, primarily due to the high cooling rate early in the batch cycle. A large number of nuclei are formed that cannot grow to the desired size. Also, crystal growth (frosting) on the heat transfer surface can be intensive and cause insufficient cooling throughout the rest of the batch. These problems can be largely overcome by the use of the programmed cooling curve, as shown in figure, that is the reverse of the natural cooling curve.

The batch crystallizer temperature set point should be lowered slowly at the start and rapidly at the end to provide a cooling curve that optimizes crystal growth

Simulations that include operating conditions and equipment design with Digital Twin can help find and confirm the best control strategies.

For much more knowledge, see the ISA book Advanced Temperature Measurement and Control, Second Edition (use promo code ISAGM10 for a 10% discount on Greg’s ISA books).