Some lessons learned using expert systems for process control

Two expert systems are used to monitor two industrial processes, looking for problems. The processes are an adipic acid reactor and a heat exchanger. When a problem occurs, the process operator is alerted and is told the problem and its probable cause. Expert systems have also been used to tune proportional-integral-derivative controllers and to help select flow meters to suit customer requirements. Experience with these expert systems has led to practical results and to some lessons for using expert systems for process control. The lessons form the bulk of the paper and deal with limits to expert systems, how and where expert systems fit in, knowledge-base engineering, and software engineering for expert systems.