On the solution of scheduling problems for multi-purpose batch chemical plants

A solution strategy for solving the scheduling problem in the case of multi-purpose batch chemical plants is described. The plant may contain several identical examples of any of the types of process unit. The problem is characterized by requirements such as —branching in batch and device —maintenance of a fixed time regime in the production of one batch —changeover times when products are changed, etc. The centre of the heuristic strategy of solution is an exact algorithm which examines whether or not a batch with a given starting time can be scheduled. The appropriate subprogram can be easily incorporated into programs realizing known heuristic scheduling principles, which were developed for solving simpler problems. Examples with 68 process units, 600 shits and 350 batches have been computed on a EC 1040 computer in 10–15 minutes.