Optimal Production Planning Models for Parallel Batch Reactors with Sequence-dependent Changeovers

Muge Erdirik-Dogan and Ignacio E. Grossmann Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 February 2007 Abstract In this paper we address the production planning of parallel multi-product batch reactors with sequence-dependent changeovers, a challenging problem that has been motivated by a real world application of a specialty chemicals business. We propose two production planning models that anticipate the impact of the changeovers in this batch processing problem. The first model is based on underestimating the effects of the changeovers that leads to an MILP problem of moderate size. The second model incorporates sequencing constraints that yield very accurate predictions, but at the expense of a larger MILP problem. In order to solve large scale problems in terms of number of products, reactors or length of the time horizon, we propose a decomposition technique based on rolling horizon scheme and also a relaxation of the detailed planning model. Several examples are presented to illustrate the performance of the proposed models.