Network-wide campaign planning for multi-stage processes in the chemical industry

Nowadays, manufacturing in process industries mostly takes place in branched supply networks consisting of several plants which are located at different sites and linked by complex logistics relations and material flows. Thus, a key issue of production planning and scheduling is the coordination of plant operations at different production stages considering the supply of intermediates and their transportation between various plants. This planning effort has to cope with the limited availability of resources as well as numerous storage and transportation constraints. Time-consuming and expensive setup and cleaning activities require production to be carried out in so-called campaigns. Identical production tasks are repeated in succession to reduce these unproductive times. In our paper, we propose an application-oriented approach for supply network planning in the chemical industry which is based on a novel aggregation scheme and a network flow formulation of the problem. The optimization model uses a continuous representation of time. Our approach generates a comprehensive schedule for coordinating the production activities at all plants in the network.