Intellite3

Abstract

A chemical process is represented by a large scaled and complex system complex system composed of many interacting variables and unit operations. Nowadays the structure of a chemical process tends to become increasingly complex, due to the requirement of better management of energy and raw materials, thus there exist more incentives to design better control systems for chemical plants. The design of control systems for new and existing chemical plants now constitutes the focal point of interest rather than controller design for single processing units. The control system structure of a chemical process can be synthesized by selecting controlled variables to satisfy product quality specifications, safety aspects, operational requirements, and manipulated variables to affect those controlled variables and finding the appropriate interconnection among them. These procedures have long been relying on experience and intuition of some special control engineers. Those few experts have a large body of knowledge which they utilize in designing control systems, but which is not readily available to others. Hence the design and analysis of control systems can greatly benefit from the use of computer-aided design environments, especially knowledge based expert system which is capable of dealing with chemical processing systems rather than a simple adaptation from other control fields. It is expected that knowledge based expert systems containing the knowledge in process control design will thus promote effective transformation-the specialized and intuitive heuristic knowledge to general process engineers. This work describes a comprehensive model for the process of plant-wide control system design and an expert system for synthesis and design of control systems for overall chemical processing plants. We also outlines the knowledge representation schemes for the expert system with object oriented programming concepts on control system design, control objectives and their re...