Robust Dynamic Optimization of a Semi-Batch Emulsion Polymerization Process with Parametric Uncertainties-A Heuristic Approach

Optimized exothermic semi-batch emulsion polymerization typically exhibits active arcs of the constraints for the reactor temperature. Given parametric uncertainties in the process model, this might lead to constraint violations which are a safety concern. Therefore, an approach is investigated, such that constraint violations are less likely and is hence robust feasible. The two-model approach is presented as an approximate solution. Therein, two models, the nominal and a worst-case model are optimized simultaneously. Because of the challenges in defining the worst-case, a heuristic method is presented to define the worst-case parameter and its parameter value. The results of the process optimization with the two-model approach are compared with the results of the optimization with the nominal model solely. In addition the feasibility of both optimization strategies is compared by simulating hundred different scenarios with random parameter values from the uncertainty set. The presented approximation does not guarantee robust feasibility, but path constraint violations are less likely due to the introduced conservatism compared to the original optimization.