Advanced Control Algorithms for a Chemical Polymerization Process

Butene-1 is produced from ethylene by dimerization reaction in a CSTR. Due to the exothermic reaction, serious temperature runaway occurs in the reactor. Therefore, it is important to stabilize the reaction temperature in order to maintain good quality product and safe operation. Temperature stabilization is also essential for maintaining optimal operation of high ethylene conversion and desired butene-1 yield in the face of plant upsets. The objective of this paper is, thus, to study the simulated implementation of nonlinear control algorithms such as Fuzzy Logic Control (FLC), Globally Linearizing Control (GLC) and Nonlinear Model Predictive Control (NLMPC) algorithms for temperature stabilization of such a reactor to maintain favorable ethylene conversion and butene-1 yield conditions. The simulation results revealed the capability of all the proposed control algorithms to stabilize such a reactor with some differences in their performance. In addition, the performance of the nonlinear controllers outperforms that of the standard PI algorithm in terms of providing higher yield and shorter settling time during disturbances. However, careful tuning of the parameters of these controllers is necessary without which very aggressive or even unstable closed-loop performance will be obtained.