Prepared for presentation at ESCAPE 12 symposium. Plantwide control: Towards a systematic procedure

Plantwide control deals with the structural decisions of the control system, including what to control and how to pair the variables to form control loops. Although these are very important issues, these decisions are in most cases made in an ad-hoc fashion, based on experience and engineering insight, without considering the details of each problem. In the paper, a systematic procedure towards plantwide control is presented. It starts with carefully defining the operational and economic objectives, and the degrees of freedom available to fulfill them. Other issues, discussed in the paper, include inventory control, decentralized versus multivariable control, loss in performance by bottom-up design, and recycle systems including the snowball effect