Comparative Analysis And Study On Medium Pressure Single-staged Gas Pipeline Network And Medium-low Pressure Dual-staged Gas Pipeline Network

Nowadays in most cities of China, medium-low pressure dual-staged gas pipeline networks have been replaced by the medium pressure single-staged ones gradually. But there’s still a lack of theoretical research and analysis for the medium pressure single-staged gas pipeline networks. This thesis analyzes the network structures, amounts, pipeline diameters and gas-supplication abilities of these two systems, as well as the difference between district regulator station and regulator cabinet from the aspects of application scope, pressure fluctuation etc.With the help of hydraulic calculation software, researcher did gas-supplication network planning and design for a certain area. Through the investigation statistics and scheme comparison, the difference in network structures, pipeline diameters, pipeline lengths, investments and gas-supplication abilities between the single-staged and dual-staged system were specifically compared. After the overall comparison, the following conclusions were drawn. First, the situation should be avoided that two pipelines with different pressure are laid beneath the same road. Second, it’s better to use regulator cabinet rather than district regulator station. Next, with a higher pressure, the transportation ability can be enhanced and the supplication range can be wider. Last, the gas storage capacity and peak regulation ability of medium pressure transportation and distribution system are considerable.By the means of computation, in the previous two systems with different structures, the pressure at the regulator’s exit and the hydraulic regimes of parts with lower pressure among the pipelines were analyzed. Through the relationships among the pressure before the cooker, pressure of the origin and pressure drop of the pipeline, researcher found out the range of pressure fluctuation at the users. Compared with the medium-low pressure dual-staged gas pipeline networks, in the medium pressure single-staged gas pipeline networks, the exit’s pressure of regulator is lower, the total length of low pressure pipelines is shorter and the pressure variation at the users is smaller, hence the overall pressure is more steady.To sum up, the single-staged system has an obvious advantage over the dual-staged system in both technical and economical aspects. The research results of this thesis have great significance on optimizing the structure of city gas pipeline network, enhancing the capability of gas supplication and improving the pressure before the cooker. At the same time, they can also provide some theoretical basis for the planning, design and construction work of the medium pressure single-staged gas pipeline networks.