Mass Balance of the Batch Crystallizer

In a batch crystallizer supersaturation can be achieved by cooling, evaporation of solvent, or both combined if Ac /AT) 0. If orrly one component crystalUzes, the mass balance for this component is (suspension derrsity nij = p - p, volirme fraction pj = m /) 

If the temperature remains constant during evaporative crystallization, the evaporation rate of the pure solvent (index r) is given by 

It should be emphasized that in a real crystalhzer the assrmrptions of monodisperse seed material and of absence of nucleation and growth dispersion does not apply. The formation of secondary seeds by abrasion can considerably reduce the reqirired batch time in case of a constant supersaturation but impairs the particle size distribution toward smaller sizes. 

Suspension density transient time for various flow intensities and supersatu- 

The operational parameters fluid flow and supersaturation have to be accurately adjusted according to the crystalline material (abrasion and growth habit) to form products of a desired quality (grain size distribution, grain shape, purity, etc.). The prediction of the product quality is very difficult if spontaneous nucleation occurs -even if only for a short period of time. For products in micro- or even nanometer scale, agglomeration can crucially influence the grain size distribution. 

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