A real-time knowledge based system for product quality control

An ICI plant in the north of England has two batch reactors producing a large number of products consisting of ethoxylates. It is controlled by a Foxborough Fox 1/A process sequence control computer. The task of the plant operators is to set the `recipe´ on the Fox 1/A to make products at the desired quality and to initiate and monitor the process sequence. When a batch has been produced they judge its quality and can take a sample for laboratory analysis. If they judge it necessary they may make an adjustment or take other remedial action. The paper concerns an expert system which makes recommendations to the operator when he makes his decisions. To achieve this it must monitor and form judgements on the plant and raw materials affecting product quality; provide a prediction of product quality; estimate errors in instrumentation; and provide a justification for its recommendations