An effective formulation for optimal scheduling of multistage multi-product batch plant based on due dates

A mathematical formulation for optimal scheduling of multistage multi-product batch plant with parallel units is presented. The allocations of tasks, units and stages are described by a set of binary variables. The sequence-dependent setup times of orders and the ready times of units are considered. Based on the due dates and the processing times of orders, the predefined processing sequence of orders is achieved. The continuous time representation mode is also used in the proposed model. The computations on several classic scheduling examples and comparisons with other existing models in the literatures demonstrate the proposed scheduling model can obtain the optimal solutions in a shorter time and has much fewer binary variables.