OPTIMIZATION OF POLYMERIZATION REACTORS

This dissertation deals with optimization of batch and continuous polymerization reactors.; The first part of this study is concerned with the analysis and comparison of minumum time policies for batch polymerization systems. The batch bulk polymerization of styrene is simulated with an accurate kinetic model and realistic operation conditions. A policy which minimizes the time to reach a prescribed conversion is compared with one including some property of the molecular weight distribution as an additional target. Different numerical techniques are tested and compared.; The second part of the study is related to the optimization of large disturbances in continuous polymerization reactors. The polymerization of styrene in solution is chosen to simulate the "start-up" and "change of specification" problems. The numerical solution requires development and/or adaptation of special algorithms for stiff systems and singular controls. Several fixed end time policies are evaluated, and the effect of different control variables is analyzed.; The third and last part of this study deals with steady state optimality of continuous copolymerization reactors. The multiobjective nature of the problem requires a vector objective formulation through the concepts of Pareto optimality and non-inferior sets. A copolymerization process in solution is simulated for vinyl acetate-methyl methacrylate and styrene-acrylonitrile systems. The determination of the non-inferior sets permits a clear decision on trade-offs related to the operating conditions and/or product properties.