A general MILP model for scheduling of batch process with sequence-dependent changeover

In the scheduling models for batch processes, changeovers are considered to be sequence-dependent, which is the most general situation, or only unit-depended. In recent literature, most continuous-time methods only consider unit-dependend changeovers, which cannot represent the rea world situation In this paper, a new M-ULP model for scheduling of batch process with sequence-dependent changeovers has been presented. It is based on a new continuous-time representation method that dose not rely on the definition of time slots. Accessorial binary variables are introduced to indicate whether there is any task processed at each unit so that the sequence constraints are presented in a more compact way. Computational case study has shown the efficiency of the new model.