Dynamic Modelling and Optimisation of α-Lactose Monohydrate Seeded Batch Cooling Crystallisation

摘要

This work validates the model equations of a seeded batch cooling process to produce α-lactose monohydrate from highly pure syrup. Experiments are conducted in 2L and 20L crystallisers under various seeding and cooling strategies, obtained from solving a dynamic optimisation problem. Using a nonlinear least square method the best curve fitting of experimental data to the model yields k_g and n, two constants used in the growth rate equation. The value of n = 2.7 can be fixed regardless of sizes of seeds and crystallisers but k_g must be estimated for different seeding weights. The rate of nucleation must be redefined to reflect the variations in crystal median size prediction. The model can be applied to industrial scale crystallisers providing the cooling rate is slow and the seed size range is narrow.