Periodic Scheduling of Multiproduct Continuous Plants Using a Multiple Time Grid Continuous- time Formulation

This paper presents a new mixed integer nonlinear model (MINLP) for the periodic scheduling of multistage continuous plants with a single equipment unit per stage, where all units are subject to sequence dependent changeovers. The formulation is based on the resource task network (RTN) process representation, features combined processing and changeover tasks and does not require an iterative procedure over the total number of event points in the time grid. The new multiple time grid formulation is compared to a single time grid formulation through the solution of a few example problems taken from the literature with the results showing that the proposed formulation is significantly more efficient computationally.