Review: Control Schemes for Low Density Polyethylene Reactor

Abstract

Low density polyethylene (LDPE) is one of the most common produced polymers in the world. LDPE is commonly produced using fee radical polymerisation process in high pressure environment. Polymerisation process pose significant challenges to the industrial community as the process is difficult to control with high nonlinearity behaviour and fast dynamic response. Control problems can also arise from LDPE grade switching and reactor’s fouling effect. The infrequent long sampling time of laboratory measurement and unreliable online instrument measurement can make the LPDE quality monitoring become more difficult. The heart of polymerisation process is the reactor. A good control of the reactor will exhibit smooth production of LDPE. In this study, a brief review of past and recent control schemes that had been developed for LDPE process is presented. This review focused on the control schemes implemented in tubular and autoclave reactor which covers type of control scheme, process model, process estimator, and control variables used. The availability of important industrial quality parameters such as Melt flow index and Gloss index is also addressed. This review highlights the importance of nonlinear control in polymerisation process and future works related to it.