A Continuous-Time Formulation for Scheduling Multi- Stage Multi-product Batch Plants with Non-identical Parallel Units

Multi-stage multi-product batch plants with non-identical parallel units are quite common in the batch chemical industry. Scheduling production in these plants optimally is a complex task that has received limited attention in the literature. In this work, we propose a new continuous time-representation using asynchronous slots and report a mixed integer linear programming (MILP) formulation for the short-term scheduling of such plants. Using several examples, we show that our formulation is simpler, tighter, and performs better than previous formulations.