DESIGN OF MULTIPURPOSE BATCH PLANTS WITH MULTIPLE PRODUCTION PLANS BASED ON CYCLIC PRODUCTION

The design challenge in multipurpose batch plants is optimizing plant configuration and equipment size under the constraints of multiple pro duction plans, and these decision variables are interactive with each other through scheduling. To optimize these decision variables, the ev olutionary design method on the basis of scheduling according to cycli c production (cyclic scheduling) is appropriate, and batch composition of a cycle (number of batches and their relative batch sizes per one- cycle) for respective production plans should be specified beforehand. In this study, a method to specify the batch composition that enables optimal design is developed. From the viewpoint of optimizing plant c onfiguration, the common batch sizes for a multiple number of producti on plans (core batch sizes) are introduced for each product, and speci fying the batch composition on the basis of these core batch sizes is converted into assignment problems, from the viewpoint of optimizing e quipment sizes. These assignment problems are formulated into IP (Inte ger Programming) models, and the optimal design satisfying multiple pr oduction plans becomes possible. The effectiveness of this method is d emonstrated through an example problem.