EXACT SOLUTION OF THE NO-WAIT FLOWSHOP SCHEDULING PROBLEM WITH A COMPARISON TO HEURISTIC METHODS

Intermediate storage utilization provides a key constraint in the scheduling of multistep batch processes. In some cases, unstable intermediates must be processed without delay at any production step so that intermediate storage may not be used. In a flowshop, such a no-wait scenario can be reduced to a traveling salesman problem. This paper details the application of an exact branch and bound algorithm for the traveling salesman problem to solve the no-wait flowshop scheduling problem. We present and solve an example problem typical of those found in the chemical industry. In addition, we present data comparing two-exchange and simulated annealing heuristics with the exact algorithm for various problem sizes.