ISSUES IN SOLVING LARGE-SCALE PLANNING, DESIGN AND SCHEDULING PROBLEMS IN BATCH CHEMICAL-PLANTS

The solution of the planning/design/scheduling problem is limited by e xisting solution algorithms and computing resources. A combined planni ng/scheduling problem over an extended horizon of several months yield s a formulation with thousands of variables. A natural approach presen ted earlier is to decompose the large problem into smaller ones, the s olution of the decomposed problems constituting the solution to the or iginal problem. The decomposition is however, a nontrivial task becaus e of the global decision making process. Infeasibilities may arise at the lower stage since we have only considered the design/planning stag e at a macroscopic level, therefore, a diagnostic formulation delta RF is presented here. The power of the approach in identifying the infea sibilities and its use to solve the design problem is discussed in thi s paper. Illustrative examples for batch plant design are presented.