Heat Exchange During Crystallization

Rearranging Eq. (7-41) with respect to the crystal product rate, S gives 

The heat flow Q supplied or removed during crystallization is derived from a heat balance over the crystallizer (Fig. 7-23). For the general case of a combination of a cooling and evaporation crystallization, 

From Eq. (7-42) special cases are easily deduced, for example, pure cooling crystalli- 

The crystallization enthalpy has to be found experimentally. An approximation is possible according to Chapter 1.4.6 if points T], and 7, X2 on the solubility curve are known 

The correct sign of Qc should be used in application of Eq. (7-44). Q 0 indicates heat supply, Q Q indicates heat removal. 

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Bark, M., and Zachmann, H.G. Simultaneous measurements of smaU-angle X-ray-scattering, wide-angle X-ray-scattering and heat-exchange during crystallization and melting of polymers. Acta Polym. 44 no. 6 (1993) 259-265. 

This hypothesis relates very well with the observations made by Oh et al. (22) during pilot-plant-scale crystallization and processing of palm oil in a scraped-surface heat exchanger line for margarine and shortening, as shown in Figure 2. 

Furthermore, wine must remain at low temperatures during filtration until the sediment has been removed, to avoid the crystals dissolving again. Heat-insulated filters are used and a heat exchanger at the filter outlet contributes to the cooling process. 

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