MULTIOBJECTIVE OPTIMIZATION APPROACH TO SENSITIVITY ANALYSIS - WASTE TREATMENT COSTS IN DISCRETE PROCESS SYNTHESIS AND OPTIMIZATION PROBLEMS

This paper presents an approach for determining the sensitivity of the maximum net profits of a chemical process to changes in the waste treatment cost when discrete terms must be optimized. The approach employs a basic relationship between the sensitivity problem and a multiobjective optimization problem that maximizes profiles and minimizes waste. It is shown that all solutions of the original process optimization problem must lie in the concave portions of the solution set of the multiobjective problem and that a simple transform exists between the multiobjective optimization problem and the sensitivity problem. The proposed approach uses a modified form of the outer approximation method to identify discretely different regions of the multiobjective solution set. The complete solution set is generated with a sequential approximation algorithm. The approach is illustrated with a case study of the production of ethylene glycol from ethylene oxide and water.