ON THE DESIGN OF MULTICOMPONENT BATCH DISTILLATION-COLUMNS

This paper presents a mathematical programming approach to the optimal design of batch distillation columns. Both capital and operating cost contributions are taken into account. The column design parameters an d operating policy are determined simultaneously. Treating the number of trays in the column as a decision parameter necessitates the introd uction of a superstructure that encompasses all possible tray numbers between a lower and an upper bound. The mathematical formulation leads to a mixed integer dynamic optimisation problem which is solved using an outer approximation/augmented penalty algorithm comprising a conti nuous subproblem involving the optimisation of a column with a fixed n umber of trays and a master problem involving the solution of a. small mixed integer linear programming (MILP) problem that determines the n umber of trays to be considered at the next iteration of the algorithm . The methodology presented is illustrated by its application to the d esign of a plant involving a sequence of two batch distillation column s. (C) 1998 Elsevier Science Ltd. All rights reserved.