A hybrid framework that uses Mathematical and Constraint Programming for the scheduling of batch chemical processes is proposed. Mathematical programming is used for the high-level optimization decisions (number and type of tasks, and assignment of equipment units to tasks), and Constraint Programming is used for the low-level sequencing decisions. The original problem is decomposed into an MILP master problem and a CP subproblem. The master MILP is a relaxation of the original problem, and given a relaxed solution, the CP subproblem checks whether there is a feasible solution and generates integer cuts. The proposed framework is based on the hybrid algorithm of Maravelias and Grossmann ([1],[2]), and can be used for different objective functions and different plant configurations. In this paper we present the simplifications and enhancements that allow us to use the proposed framework in a variety of problems, and report computational results.
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