Estimation and control in polymerization reactors. A review

Abstract

The control of polymerization reactors is particularly arduous for several reasons; (a) difficulty in specification of the control objectives; (b) high exothermicities and viscosities involved: (c) complicated process dynamics: and (d) problems with measurement of the polymer structure. Computer control has now simplified many tasks such as sequential operations of batch reactors; but no less important, it has made feasible the implementation of elaborate state estimation and control algorithms. The tendency in the polymerization industry and in current research centers is centered on producing ‘tailor‐made’ polymers from the view of its microscopic and/or macroscopic structures. To this end, several solutions have been proposed. For example, in the ‘chemical approach’, open loop methods have been developed based on the detailed dynamic models of the processes. Any control technique requires a knowledge of the process to be controlled through mathematical models. These models may be developed either from detailed mass and energy balances, or through empirical input‐output or “black‐box” techniques. The most promising control techniques are probably optimal control, adaptive control, and their combinations. Optimal control is powerful because it utilizes directly the detailed non‐linear plant model. Adaptive control developed for linear plants has already proven satisfactory, in spite of the highly nonlinear nature of the polymerizations. Undoubtedly, improved solutions will be obtained when this technique is extended to non‐linear systems.

Continuous soluble Ziegler‐Natta ethylene polymerizations in reactor trains. I. Mathematical modeling

“…1,2 This is particularly true for soluble ethylene ZieglerNatta polymerizations, as the reaction mechanism comprises a large number of reaction steps and the kinetic behavior of the catalyst species depends on many operation variables. 2,3 Polyethylene (PE) is the most produced thermoplastic in the world, which shows that proper understanding of PE manufacture is of great economical importance.…”

Hybrid modelling and kinetic estimation for polystyrene batch reactor using Artificial Neutral Network (ANN) approach

“…Elicabe and Meira [1] reported three basic problems related to polymerization mathematical models: (1) These models are of high nonlinear nature and therefore, all the control theory developed for linear systems is not strictly applicable. (2) Model parameters are in many instances unknown, and their estimation may be extremely difficult.…”

Control of Polymer Quality in Gas Phase Polyethylene Reactors Using Feed Flow Rates

“…Therefore, it is important to monitor and control MWD during the industrial production of polymers. A significant amount of research has been done in the area of control, monitoring and modelling of polymerization reactors; excellent reviews have been given by several researchers [1][2][3][4]. A careful study of previous works, with focus on the description of polymer MWD, results in the following conclusions:…”