Empirical modelling and control of processes with recycle: some insights via case studies

Abstract Issues related to the identification and control of systems with recycle of material and/or energy are investigated via simple case studies. We aim for high performance control using recycle compensators that can be easily implemented on industrial DCS systems. The modelling strategy centers around system identification and/or decomposing the overall process dynamics into a direct effect component and a recycle component. When fundamental process models are available, such decomposition is relatively straightforward. In their absence, the models required for controller design may only be gained via plant tests and subsequent system identification. This study will examine the issues related to the empirical identification of integrated systems such as the proper use of available sensor information and appropriate implementation of the recycle compensator. Though only two case studies are presented here, the principles and conclusions are broadly applicable to industrial chemical process systems.

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