Fault Diagnosis On Cargo System Of LNG Carrier Based On Expert System

High quality, cleanliness of energy consumption is the important symbol of modern society development. In 1990's, the international energy sector alleged that the 21st century is the century of natural gas." Over the years, because of persistently high oil prices, many countries have gradually increased the consumption of natural gas. Natural gas demanding is increasing year by year.LNG (Liquefied Natural Gas) carrier is the main conveyance of LNG. It is, in the shipbuilding industry, as the "crown jewel", and it is widely recognized as high-tech, high difficulty, high value-added "three high" products. The cryogenic liquid cargo system is characterized its high-tech, highly difficult. LNG is-163℃ultra-low temperature liquid. It is clean, efficient and cheap, though can result in many potential risks. For example it can cause chilling injury, workers suffocated, and even explosion. At the same time, LNG may lead LNG boiling gasification and liquid cargo rolling due to error operation or system failure, then, the rising pressure in the cargo hold may have disastrous consequences. Therefore, investigation on LNG cargo system expert system of fault diagnosis can bring a significant economic value and broad application prospects.Subjective Bayesian approach, as one of the most common method of reasoning. has a very distinctive characteristic:it is built on the basis of probability theory, so, it has a solid theoretical foundation. At the same time, it uses experts' priori probability in the field, not only avoid the probability of large amounts of data Statistics, but also help to prevent inconsistencies in the reasoning network, transmission and spread resulting miscalculations. Therefore, this system adopts subjective Bayesian theory as the reasoning model, combining prior probability of cargo system's equipments and accessories to design fault diagnosis expert system software.This software bases on Windows XP operating system, using MATLAB 7.0 and Excel. It includes the collection of all sorts of equipments and accessories' fault types, including the failure probability, of LNG cargo system. It also includes the operation standards of different courses for reference. The system can quickly identify potential troubles, and provide the probability of the existence of various faults when input the state of cargo system.