Formal techniques for the procedural control of industrial processes

• Main Author: Alsop, Nicholas James
• Published: Imperial College London 1997
• Subjects: 660
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488461

This thesis examines the theory and application of procedural control to chemical processes of industrial scale. Procedural control formally addresses the discrete and logical aspects of process control as required for batch chemical processes or during start-ups, shut-downs and changeovers of continuous chemical processes. Procedural Control Theory encompasses process modelling, specification, controller synthesis and analysis. In particular, techniques within Procedural Control Theory have been developed for the design of single controllers for chemical systems modelled as Discrete Event Systems, such that they conform to specifications and meet a set of desirable properties (Sanchez, 1996). Before now, these techniques were applicable only to small systems. Here Procedural Control Theory is extended using modular techniques to deal with process systems of industrial scale. The main theoretical result is that the same set of desirable controller properties can be retained by an industrial controller, comprised of a set of modular controllers. In a modular configuration, the second problem to address is that of controller inhibiting. A controller inhibit is a mechanism which disables the simultaneous operation of two noncooperative controllers. A control theoretic criterion is supplied in this thesis for the purposes of designing inhibit policies. In order to apply the theory described here, algorithms are presented for the translation of the controller formalisms into industrial sequential control languages. Finally, two case studies are presented which demonstrate the theory and techniques. Firstly, controllers are designed for three operations of a Cleaning-In-Place unit procedure in a multipurpose, multiproduct batch pilot plant. Inhibit design techniques are then demonstrated for an industrial paste plant, characterised by a high degree of resource sharing and interlocking