UNCOVERING THE RELEVANCE OF MODELING TRANSFER TIMES IN THE SHORT-TERM SCHEDULING OF MULTIPURPOSE BATCH PLANTS

E. CAPON-GARCIA; S. FERRER-NADAL; C.A. MÉNDEZ; L. PUIGJANER

Massachusetts, USA

Conferencia; Foundations of Computer-Aided Process Operations 2008; 2008

CACHE organization

A critical feature to be considered when dealing with multi-stage batch plants scheduling is the modeling of the material transfer activities taking place in the process. Transfer tasks consume a period of time during which a proper synchronization between the equipment units supplying and receiving the material is mandatory. Most existing mixed-integer linear programming (MILP) optimization approaches have traditionally dealt with the batch scheduling problem assuming zero transfer times, and consequently, no synchronization between consecutive processing stages has been contemplated. The problem simplification relying on negligible transfer times may work properly for the scheduling of multi-product batch plants with similar product recipes. However, it is demonstrated in this work that ignoring the key role of transfer times may seriously compromise the feasibility of the scheduling whenever shared units and storage tanks, material recycles and bi-directional flows of products are to be considered.