Boiler tube leakage detection expert system

Abstract Efficient and reliable operation is the main requirement of the modern power plant. The most probable reason for failure in the power plant boiler is tube leakage. It is usually detected when urgent action is needed to prevent accidents in the plant. Advance detection of boiler leakage is of primary interest to secure maintenance planning and prevent the adverse effect of tube rupture. The development of the tube failure detection system is a demanding issue for the large power plant boilers. The present paper describes the development of an expert system for detecting boiler tube leakage. The system is based on selected diagnostic variables obtained by radiation heat flux measurements. A sensitivity analysis of the diagnostic variables is performed. A three-dimensional mathematical model of the boiler furnace is used to obtain the confidence level for the minimum leakage to be detected. The design of the expert system is based on relative values of the radiation flux reading as the diagnostic parameter. The leakage detection expert system is designed in the knowledge base environment, comprising the knowledge base containing facts, information on how to reason with these facts and inference mechanisms able to convert information from the knowledge base into user requested information. The knowledge base is based on the object-oriented structure with the definition of the object LEAKAGE. The object class LEAKAGE is composed of subclasses SENSOR and CASES. The inference procedure uses a set of procedural processes in the preparation of diagnostic variables reading for the decision making process. A fuzzification process is used for conversion of actual diagnostic values into semantic values. The several steps of the inference procedure lead to the logic processing of individual and collective representation of diagnostic variables represented in the knowledge base. A number of examples are given for leakage detection based on the expert system reasoning and monitoring representative situations which are imminent to the set of parameters describing situations preceding boiler tube rupture.