Multiobjective optimization of an industrial wiped-film pet reactor

Multiobjective optimization of a third-stage, wiped-film polyester reactor was carried our using a model that describes an industrial poly(ethylene te rephthalate) reactor quite well. The two objective functions minimized are the the acid and vinyl end group concentrations in the product. These are t wo of the undesirable side products produced bl the reactor. The optimizati on problem incorporates an endpoint constraint to produce a polymer with a desired value of the degree of polymerization. In addition, the concentrati on of the di-ethylene glycol end group in the product is constrained to lie within a certain range of values. Adaptations of the nondominated set-ring genetic algorithm have been developed to obtain optimal values of the flue decision variables: reactor pressure, temperature, catalyst concentration, residence time of the polymer inside the reactor, and the speed of the agi tator The optimal solution was a unique point (ilo Pareto set obtained). Pr oblems of multiplicity and premature convergence Mere encountered A "smooth ening" procedure is suggested to generate near-optimal operating conditions . The optimal solution corresponds simultaneously to minimum values of the residence time of the polymeric reaction mass in the reactor.