The Development of Computer Aided Risk Assessment System and It's Application

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An algorithm for application of knowledge engineering to automated HAZOP has been developed. The development of the expert system for HAZOP first required the consideration of the types of knowledge required for the study, and how this information could be incorporated into the system. The knowledge required to perform HAZOP can be separated into two types ; (1) the generic knowledge, (2) the plant specific knowledge. This knowledge interacts with each other to perform HAZOP analysis.The generic knowledge consists of guidewords, property words (process words), action required, components failure and fault propagation models, which are described in the form of decision table and suggested actions. This knowledge is developed in a process-independent manner and is applicable to wide variety of process flow sheets. The plant specific knowledge consits of information about materials, reactions, and the plant structure (P and I diagram). The plant specific knowledge varies from plant to pla … More nt an has to be provided by the user. Expert system for HAZOP consists basically of the knowledge bases (the plant specific knowledge base, the generic knowledge base) and the inference engine. The user requests the expert system to perform the HAZOP analysis by specifying a process variable deviation in a process unit or pipe line. Each process variable of equipment is studied in sequence by searching the knowledge base, using key words to describe deviations. And this search builds cause and consequence equations and develops action items. Cause equations describe logical relationships between considered deviation and its possible causes. Consequence equations describe how major items of equipment and process variables respond to single deviation. The computer program translates cause equations and consequence equations into HAZOP and tabulates in HAZOP record sheets. The expert system for this work is written in Prolog - a logic programming language. The language is excellent for expressing logic and performing symbol manipulation and hence has ready application to the expert system. The present application was developed in an EWS environment. Less