Identification and control of an industrial polymerisation reactor

This paper deals with the application of model identification and control to an industrial polymerisation process. The final control objective in the present process is to obtain a polymer of a viscosity as homogeneous as possible. The process has two inputs : the catalyst feed rate and the air flow rate in the reactor. The first input is the control input, and the second is a measured disturbance. The process model is identified from industrial data. The model identification (e.g. System identification-theory for the user. Englewood Cliffs, NJ: Prentice-Hall, 1987; and Model validation and model structure determination. Englewood Cliffs, NJ: Prentice-Hall, 1989.) also accounts for a drift in the gain of the transfer function between the polymer viscosity and the catalyst feed rate. The drift is due to the coating of the reactor with high viscosity polymer. The identified model is used to design a predictive controller with feedforward action of the air flow rate. The controller is tested in numerical simulation. The present study covers all aspects from the model structure and parameter identification to the control design and control performance evaluation. (C) 2004 Elsevier Ltd. All rights reserved