Evaluation Of City Gas Transmission And Distribution System Based On Value Engineering

City gas transmission and distribution system which takes the function to supply the qualified gas for types of users is an important part of the municipal establishments. Evaluating gas transmission and distribution system reasonably is significant to reduce the project investment and improve the system's function. According to the present situation of national gas engineering, the characteristics of the evaluation methods used in gas transmission and distribution system are analyzed, considering and quantifying the factors affecting the system are put forward to make the evaluation result more objective. By expounding the general principle and operation program of value engineering (VE), the basic and assistant functions of city gas transmission and distribution system are differentiated; functional system chart of the system is constituted. For the problem of function measure in VE, the method of function quantification is brought forward to define target cost or the importance coefficient of functions. The effectiveness of gas transmission and distribution system, the reliability of the system, the system's hydraulic characteristics, the safety of the pipeline, the system life cycle and construction schedule, etc. are introduced as the system evaluation quantitative indexes. Analytic hierarchy process (AHP) is used to determine the weights of the indexes. The life cycle cost of the gas transmission and distribution system is analyzed and the computation methods are given. Based on the principle of VE, city gas transmission and distribution pipeline system is analyzed and the evaluation function indexes system for pipeline system is constituted. The gas pipeline's functions are analyzed and the function of gas pipeline is divided into four parts: transporting gas, distributing gas, transporting pressure and storing gas. The quantification methods of every part are given. Using value coefficient as the evaluation index, the pipeline's hydraulic characteristics are evaluated using VE method. Based on an example of gas transmission and distribution system, value engineering is used to analysis and to evaluate the projects and the optimal one is selected. The annual charge method and the fuzzy matter-element optimization method are used to evaluate the project example; the selected optimal project is the same to value engineering method.