Plantwide Optimal Grade Transition for an Industrial High-Density Polyethylene Plant

Abstract

Industrial polymer plants are composed of reactors and downstream processes such as separators, dryers, and pelletizers. The polymer properties are delayed and changed in the downstream processes because of process dynamics. The polymer grade is determined by the properties of both the polymer slurry from the reactors and the polymer pellet from the pelletizer. Therefore, the grade transition strategy must be optimized in a plantwide viewpoint, and the models of downstream processes must be included in the optimization problem. In this study, a plantwide optimal grade transition strategy is proposed using the models of the reactors and the downstream processes, and the results are compared in a plantwide viewpoint. The plantwide grade transition time using the entire set of process models is shorter than that using the reactor model only.