Batch distillation of binary mixtures: preliminary analysis of optimal control

The present work concerns the distillation of a binary non-ideal zeotropic mixture in an N-stage batch column under total condensation and constant vapour flow rate assumptions. The aim is to maximize the final product of desired purity using the reflux as a control parameter. We discuss methodological aspects of the numerical resolution, and apply the direct method based on a full discretization of the optimal control problem. We show that if the number of plates is just sufficient or is big enough to assure the desired purity of the product, the optimal solution is very close to the cyclic-like policy reported by other authors in a different context. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.