Study On Expert System For Fault Diagnosis Of Circulating Fluidized Bed Boiler

Circulating fluidized bed (CFB) combustion technology has developed rapidly around the world since being invented by virtue of its wide adaptability to fuels, high combustion efficiency and well controlled environment pollution. The Circulating Fluidized Bed Boiler (CFBB), with the CFB combustion technology introduced, is welcomed by the worldwide power plant now. With the development of science and technology, the installed capacity of the CFBB power units turns to the large scale; the structure of the boiler unit becomes more and more complex; as a result, the fault diagnosis for the boiler equipment is getting more and more difficult. The primary purpose of developing the expert system for fault diagnosis of CFBB is to find out the reason of the malfunction immediately, to decrease the probability of accidents caused by fault and reduce maintenance costs after the fault of boiler occurs.The CFBB combustion system was studied in this paper to analyze the combustion faults occurring during the operation of boiler and to find out solutions to the faults. The method of mixed programming between the tool of expert system CLIPS and the Visual C++ 6.0 was adopted to carry out the qualitative analysis and calculation analysis of faults. The fault qualitative analysis was achieved by the CLIPS inference engine, while the fault calculation analysis and the contact surface programming were realized through the Visual C++ 6.0, thus the CFB combustion fault diagnosis expert system was developed.First of all, the knowledge of the expert system was introduced and the method of constructing expert system was developed. The composition, the operational mechanism and the method of knowledge expression of the tool of expert system CLIPS were studied, and the combustion faults, which occured during the operation of boiler, were arranged and coded into the rule library according to the knowledge expression method of CLIPS. Then the interface between the CLIPS and the Visual C++ 6.0 was studied, and the interface programming and the thermodynamic calculation relying on the boiler operating variable were achieved by the Visual C++ 6.0, the faults of the high flue gas temperature was also analyzed.At last, the expert system was tested by means of simulating faults of 75t/h CFBB. It was showed by the test results that this expert system could carry out the calculation analysis of the boiler combustion faults, and could get the reason and the processing method of faults through the qualitative analysis of the malfunction using the reasults of the calculation analysis.