Study On Fuzzy Comprehensive Valuation For Leakage Risk Of Urban Gas Pipe Network System

With the rapid development of urbanization,natural gas,as a clean,high-quality and efficient energy,is taking an increasing proportion in urban energy structure.Natural gas is flammable and explosive.If leakage and explosion occur during transmission and distribution,serious losses will be caused.The urban gas pipe network system is an important urban infrastructure and the lifeline to guarantee the daily life of residents and the normal operation of industrial production.It is of great practical significance to carry out risk assessment for urban gas pipe network system,which is beneficial to maintain and manage the system according to plan and pertinence.This paper takes the high pressure pipeline system of natural gas in the western part of a city in East China as the object of study to evaluate and analyze the leakage risk of this system.First,the archival data of the pipes and their ancillary facilities of the gas pipe network system should be consulted,relevant information should be summarized according to the topology of the pipe network system,and possible hazardous sources should be analyzed and identified according to the material properties and working principles of the pipes and their ancillary facilities.Taking the leakage risk of gas pipe network system as the top event,listing all the risk factors of leakage as far as possible,establishing the failure fault tree of the gas pipe network system in the studied region,analyzing the structural importance of the fault tree by solving the minimum cut set and the minimum path set of the fault tree,and sorting the leakage risk factors of the system.Finally,a complete evaluation index system for leakage risk of regional gas pipeline system is established.The degree of leakage risk of pipelines and ancillary facilities of regional gas pipeline system is given by expert scoring method.Analytic hierarchy process(AHP)is used to determine the weight of each evaluation index to the target layer.Fuzzy comprehensive evaluation method is used to evaluate and analyze the leakage risk of regional gas pipeline system.The results show that the comprehensive evaluation of leakage risk degree of five pipeline systems divided by management scope is lower than "general risk".The risk degree of pipeline IV is the lowest,which is between "low risk" and "lower risk".The risk degree of pipeline II is the highest,which tends to be "general risk".Considering the regional gas pipeline network system separately according to the pipeline and its subsidiary facilities,the average risk degree of regulator is higher,and the risk degree of individual regulator can tend to "higher risk".The results of the study on the leakage risk of gas pipeline system can be used as a reference for making daily or regular maintenance plans of gas pipeline system.