Application of fuzzy logic in the control of polymerization reactors

Polymer reactors are ideal candidates for the application of fuzzy control. Many polymerization reactions are difficult to model, process measurements are often only available from laboratory analysis at infrequent time intervals and trace impurities can have a marked effect on the reaction. All these factors are manifested in changing polymer properties, which makes control, using a conventional approach, difficult. Over the years, however, process operators have developed the ability to control the reactors under varying conditions. This article outlines how this experience was used in the development of a fuzzy control strategy, and the manner in which feedforward control was incorporated into the design. It also addresses the problem of tuning fuzzy controllers and describes some of the implementation difficulties