Fuzzy Fault Tree Analysis For Safety Research Of LNG Ships During Loading/Unloading In The Yangtze River

As a clean and efficient energy source,liquefied natural gas(LNG)is widely used in the development of the national economy and people's daily life.As the demand for natural gas in China increases,it is difficult for pipeline transportation to meet the demand for use.LNG transportation into the river is the trend of the times..Because LNG has special dangers such as low temperature,flammability and explosion,it is easy to form an explosive mixture with air.The safety of LNG shipping has always been a hot issue that needs to be solved urgently by the inland shipping industry.The loading / unloading link is an important part of LNG water transportation,and it is also a high-risk link.Due to the characteristics of working time period and complicated operation procedures,it is easy to cause casualties,environmental pollution and economic losses.Compared with coastal ports,the navigation environment of the Yangtze River is more complicated,and the transportation of LNG ships in the Yangtze River is also unique.There is relatively little research on the safety of inland river LNG shipping in the shipping industry.It is of great significance to carry out safety research and risk prediction of LNG ship loading / unloading in the Yangtze River to protect life and property and protect the water environment.This paper builds a risk prediction model for LNG ship loading / unloading based on fuzzy fault tree analysis.On the basis of summarizing the physical and chemical properties and potential hazards of LNG,LNG ship type,loading / unloading operation flow and historical accident statistics of LNG ships worldwide,the risk identification of possible dangerous sources during loading / unloading is carried out.Then combined with the characteristics of the Yangtze River navigation environment and the cause of the accident,the fault tree analysis method was used to establish the fault tree of the LNG ship loading / unloading in the Yangtze River,and various possible ways of loading / unloading failure were clarified.The traditional fault tree analysis requires a large amount of statistical data.Since the navigation environment of the Yangtze River is quite different from that of the seaport,in order to avoid data errors,the expert judgment method is used to calculate the failure probability.In the process of fuzzification,the consensus decision method is used to synthesize expert opinions.By defuzzifying the output process,the clear probability of the top event is obtained,and finally the fuzzy importance of the basic event is obtained and sorted,in order to find out the weak link of the system more accurately.A case study of a LNG terminal in the Jiangsu section of the Yangtze River was carried out to study and analyze the risk of loading / unloading of LNG ships.The results show that the calculation result of this model is slightly larger than the statistical frequency of LNG ship loading / unloading accidents worldwide,and the calculation results are highly consistent with the actual situation.The credibility and effectiveness of the model.Based on the analysis of the results of risk assessment,combined with the characteristics of LNG ship loading / unloading operations,the accident prevention measures were proposed to ensure the scientific management of LNG ship loading / unloading operations and improve the safety level of LNG ship loading / unloading.The research results of this paper can provide a theoretical basis for the safe entry of LNG ships into the river,and provide scientific guidance for shipping managers and decision makers to develop safety measures.