OPTIMAL OPERATION OF ETHYLENE POLYMERIZATION REACTORS FOR TAILORED MWD

A comprehensive steady-state model of the high-pressure ethylene polymerization in a tubular reactor that is able to calculate the complete molecular weight distribution (MWD) as function of the reactor axial distance is presented. MWD is calculated by means of the probability generating function technique. The model is implemented in gPROMS and included in an optimization framework that is used to determine optimal operating conditions for producing a polymer with tailored MWD. Two application examples are presented, the first involves maximization of conversion while maintaining the original MWD, and the second consists in finding the operating conditions needed to produce a polymer with a bimodal MWD.