Calculation of completion times and optimal scheduling for serial multi-product, multi-unit problems have been studied for the different types of intermediate storage options. In this study, a set of simple recurrence relations for serial multi-product multi-batch processes in ZW policy is suggested, which calculates completion times with or without non-zero transfer times and non-zero sequence dependent set-up times of the last unit (j = M) for each product (i = 1, 2, ... N). An algorithm is also proposed which calculates completion times of each unit (j = 1, 2, ..., M - 1) for a given product i, not recursively but independently in ZW policy. For the case of zero transfer times and zero sequence dependent set-up times, a mixed-integer linear programming (MILP) formulation is developed, and for the case of non-zero transfer times and non-zero sequence dependent set-up times, a mixed-integer nonlinear programming (MINLP) formulation is developed for optimal scheduling in ZW policy using newly proposed algorithm which calculates completion times of each product at each stage.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Computer Science Applications