OPTIMAL GRADE TRANSITION IN POLYMERIZATION REACTORS: A COMPARATIVE CASE STUDY

A study of grade transitions as encountered in polymerization reactors is presented. The results underscore the need for global optimization algorithms to fully realize the benefits of grade transition that are necessarily non-convex. For comparison purposes we use a non-gradient, parallel search, stochastic method, namely differential evolution (DE). Our simulations indicate that while the DE solution is highly dependent on the algorithm parameters and mutation strategy, the SQP solution depends on the initial guess value and consistently provides faster convergence. Finally, we also explore the issue of evaluating the optimal grade changeover time. All of the above issues have been demonstrated for the grade transition of polymethyl methacrylate (PMMA) in a non-isothermal CSTR.