OPTIMAL LONG-TERM CAMPAIGN PLANNING AND DESIGN OF BATCH-OPERATIONS

Long-term campaign operation of batch plants is appropriate where product demands are stable and plants may be dedicated to a small subset of their potential products for relatively long periods of time. In contrast to previous work which assumed that all of the processing steps involved in the manufacture of a product must take place within any campaign producing it, we examine the use of intermediate storage to decouple the manufacture of each product into several stages, each of which can be run independently in campaign mode. Since each stage involves fewer processing steps, more economical plant designs may be produced. We present a systematic and efficient method for optimal campaign planning and design, which considers simultaneously the problems of unit-to-task allocations and task timings. The problem is formulated as a mixed integer linar programming model (MILP) and solved by a modified branch-and-bound technique. A case study is presented to illustrate the applicability of the method.