New completion time algorithms for sequence based scheduling in multiproduct batch processes using matrix

Scheduling of batch processes involves various parameters such as batch process recipes, sequence of production and transfer policy for product intermediates. All these parameters directly or indirectly affect the makespan, i.e. completion time of a batch process. The scheduling approaches reported in past literatures mostly refer to the use of complex mathematical models for determining makespan. These models require good understanding in formulating the problem using programming techniques to find the optimal solution. The current work proposes new completion time algorithms for multiproduct batch process with two commonly used transfer policies namely zero wait (ZW) and no intermediate storage (NIS). The batch process recipes are presented in the form of a matrix which is then used to solve for the completion time using developed algorithms. Rearrangement of the matrix rows reflects the changes in production sequences possible for the specified batch process recipes which then enable the makespan to be determined accordingly for the different sequences. Designer is then provided with the production sequence options with their corresponding makespan from which a selection could be made. © 2008 The Institution of Chemical Engineers.