An MILP framework for batch reactive scheduling with limited discrete resources

C.A. MÉNDEZ; J. CERDÁ

COMPUTERS AND CHEMICAL ENGINEERING

Elsevier

Lugar: Amsterdam; Año: 2004 vol. 30 p. 913 - 946

0098-1354

Dealing with limited discrete resources in batch scheduling problems usually produce a sharp increase in the model size and computational requirements. This work introduces a novel continuous-time MILP formulation where all discrete resources including processing units are treated uniformly. Moreover, the ordering of batches at any processing unit or resource item is handled by a common set of sequencing variables so as to achieve an important saving in 0-1 variables. Pre-ordering rules significantly reducing the problem size can be easily embedded in the MILP framework. In addition, discrete resources may be sequentially assigned when real world scheduling problems are tackled. Two examples involving the scheduling of up to 29 batches in a single-stage batch plant with limited manpower were successfully solved. Comparison with prior work shows a notable reduction in the CPU time of at least two orders of magnitude.