UNIFIED PROCESS MODELING FOR HAZARD ANALYSIS AND ONLINE FAULT-DIAGNOSIS

A process modeling methodology and inference algorithms for off-line h azard analysis and on-line fault diagnosis are presented. Hazard analy sis and fault diagnosis are performed at different stages using differ ent methods, while they need similar process information such as causa l relationship and functions. Therefore, a unified process modeling is proposed, into which functions and behaviors of a process are incorpo rated. By building an automated system based upon the unified process model, the load of development and maintenance of the system can be re duced, and access to the system can be easier and friendlier. For auto mated hazard analysis, deviation and accident analysis algorithms are presented, which can infer causes and consequences of a given deviatio n based on the proposed model and identify all the possible accidents. For fault diagnosis, an inference algorithm based on an eventlist, th at is a history, is also presented, which can identify the root cause of observed symptoms in an eventlist using the proposed model. A CSTR system with a feed tank and a heat exchanger illustrates the effective ness of the proposed methodology. (C) 1998 Elsevier Science Ltd. All r ights reserved.