Control of Batch Crystallization : a System Inversion Approach

In this article a new approach to the control of batch crystallization is presented. In batch cooling crystallization the crucial control problem is to design a temperature trajectory which produces a desired crystal size distribution at the end of the batch. Traditionally, this problem is addressed in an optimization framework. Here, a completely different solution is presented. It is shown that the standard population balance model can be inverted analytically. The system inversion is performed making use of a state dependent time scaling of the population balance model. Consequently, for any desired crystal size distribution the corresponding temperature trajectory (i.e. the feed-forward control) can be determined in a straight forward way. Furthermore, exploiting the properties of the time-scaled moment model, a nonlinear feedback control is designed for the batch crystallizer, which ensures tracking of the previously designed trajectories in the presence of uncertainty. Copyright © 2006 Elsevier B.V. All rights reserved. [accessed February 8th 2013