Chemical Engineering Science, Vol.84, 656-670, 2012
Systematic design of supersaturation controlled crystallization processes for shaping the crystal size distribution using an analytical estimator
A novel methodology is presented for the systematic design of setpoint operating curves and seed recipes for supersaturation controlled crystallization processes. A design parameter for supersaturation controlled processes is introduced as a function of supersaturation, time and growth kinetics. Based on this parameter and a simplified analytical model, the supersaturation and batch time can be determined for any supersaturation controller crystallisation process, using an optimization approach to obtain a target distribution with desired shape. The approach also gives the temperature profile versus time corresponding to a particular constant supersaturation, providing a direct design approach for practical applications. Additionally, two methods are proposed that use the seed in conjunction with the supersaturation design for CSD control. One designs the seed recipe as a mixture of crystals resulting from sieve analysis, whereas the second evaluates a dynamic seed addition profile, which is able to achieve complex target CSDs. The proposed methods are exemplified for the model system of potash alum in water. (C) 2012 Elsevier Ltd. All rights reserved.