Batch crystallization fines destruction

Jones, A.G., Chianese, A., 1988. Fines destruction during batch crystallization. Chemical Engineering Communications, 62, 5-16. 

Jones, A.G., Chianese, A. and Mullin, J.W., 1984. Effect of fines destruction on batch cooling crystallization of potassium sulphate solutions. In Industrial Crystallization 84. Eds. S.J. Jancic and E.J. de Jong, Amsterdam Elsevier, pp. 191-194. 

Jones (1974) used the moment transformation of the population balance model to obtain a lumped parameter system representation of a batch crystallizer. This transformation facilitates the application of the continuous maximum principle to determine the cooling profile that maximizes the terminal size of the seed crystals. It was experimentally demonstrated that this strategy results in terminal seed size larger than that obtained using natural cooling or controlled cooling at constant nucleation rate. This method is limited in the sense that the objective function is restricted to some combination of the CSD moments. In addition, the moment equations do not close for cases in which the growth rate is more than linearly dependent on the crystal size or when fines destruction is... 

In this section, a discussion of model identification for batch crystallizers is given and a model-based control strategy is illustrated that conveniently handles input, output, and final-time constraints and is applicable to cases in which fines destruction is used and the growth rate is size dependent. This control scheme permits flexibility in objective function formulation and allows consideration of objective functions that take into account solid-liquid separation in subsequent processing steps. 

The population and mass balances for batch crystallization without fines destruction and with size-independent growth are as follows ... 

CSD control in batch crystallization can provide a significant improvement in product quality and features and in downstream processing efficiency and economics. Two important technologies considered here include fines destruction and preparation of narrow CSD. 

Fines Destruction. In the operation of industrial crystallizers, one would usually want to avoid the fines (i.e., small crystals) since they may cause difficulties in downstream processing equipment (e.g., filtration) and affect both product quality and process economics. Excessive fines may also require a relatively long batch run time to achieve the desired final size of the product crystals. Karpinski (1981) proposed a controlled dissolution of secondary nuclei in order to improve CSD from fluidized bed crystallizers. Jones et al. (1984) first described the application of fines destruction in batch crystallization of potassium sulfate solutions. Their study demonstrated the experimental feasibility of this technology to dramatically reduce the amount of fines in the final product CSD. Their theoretical predictions, obtained from population balance models, agreed with the experimental results. 

Figure 10.16 Effect of fines destruction on cumulative number distribution in a batch crystallizer. (Reprinted with permission from Zipp G.L., and Randolph A.D. (1989), Industrial Engineering and Chemical Research, vol, 28, p. 1447. 1989 American Chemical Society.)...

Figure 9.15. Experimental crystal size distributions for the batch cooling crystallization of potassium sulphate with and without fines destruction using the apparatus depicted in Figure 9.14. Added seeds 550 im fines cuf After Jones, Chianese and...

Figure 7.6 Fines destruction during batch crystallization after Jones etai, 1984)...

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