Systematic evaluation of models of different complexity for a low-density polyethylene plant

Abstract

This study deals with the dynamic modelling and simulation of low-density polyethylene (LDPE) production plant. LDPE is produced in a complex process which takes place under extreme operating conditions and may lead to nonlinear dynamics due to highly exothermic reactions and material recycles around the reactor. In principle, the process is represented by a distributed parameter system with an external coordinate (the reactor length) and various internal coordinates (the chain length of the polymer molecules, short-and long-chain branching and the number of double bounds) resulting in a large scale model. In this contribution a detailed reference model is introduced and possible model simplifications are discussed systematically from on-line optimization and control point of view.