A Bi-level Decomposition Scheme for the Integration of Planning and Scheduling in Parallel Multi-Product Batch Reactors

We address the simultaneous planning and scheduling of parallel multi-product batch reactors, a challenging problem that has been motivated by a real world application at the Dow Chemical Company. We propose a novel continuous time MILP model for the simultaneous planning and scheduling that is based on slot representation. While effective for short-term scheduling, the proposed model becomes computationally intractable for long planning horizons. Hence, we propose a rigorous bi-level decomposition algorithm that reduces the computational effort of the problem. We decompose the original problem into an upper and a lower level. We iteratively solve the upper and the lower level problems until the difference between the bounds is less than a specified tolerance.