Modelling and Scheduling of Mixed Batch/ ContinuousPlants: Investigating a Petri Net Approach

Effective scheduling of operations in the process industries has great potential for ensuring high economic returns. Traditionally, production scheduling problems in these industries have been solved using mathematical methods. The mathematical formulations, however, are still difficult to derive and severely inhibit the attainment of the potential economic benefits. Therefore, an alternative method for the formulation of scheduling problems in the process industries would be very helpful.In this study, the application of Petri nets for modelling and scheduling of batch processes has been investigated. Timed Place Petri nets were evaluated and found to be very promising for the formulation of scheduling problems in batch and mixed batch/continuous processes. Essentially, the major advantage of the proposed technique is the ability to graphically define the scheduling constraints in a Petri net model. Thus, simplification of the formulation of scheduling problems was achieved using the proposed approach.