Hydraulic Simulation And Analysis On Urban Natural Gas High-pressure Ringed Pipelines

With the development of the exploitation scale and usage scope of natural gas, transmission pipeline network system is expanding and perfecting in different regions of China. In order to solve the problem that integrated transmission pipeline network system with multi-gas source and high parameter existing in design, renovation, operation, management and other aspects, a hydraulic model of the pipeline network should be established to master the operation rules of network, and to ensure safety reliable continuous operation of pipeline network system.In order to establish a hydraulic model of gas pipeline network system, pipe pressure drop equations, nodal flow equations and ring energy conservation equations are set up in matrix form, and the nodal analysis method or loop analysis method are used solving matrix equations. The nodal analysis method is based on nodal flow equations to solve nodal admittance matrix, while the loop analysis method is based on ring energy conservation equations to solve loop impedance matrix by any particular solution of homogeneous linear equations. In this paper, the non-pipe element model is described as the relationship between inlet pressure, outlet pressure, and the flow through element. Frictional resistance coefficient is calculated by the method of bisection, Newton iteration method or secant iteration method.In this paper, taking the high pressure natural gas pipeline network system of a city in 2020 as an example, a multi-gas source network modelling basede on MATLAB is established to simulate the hydraulic conditions in peak houre, low houre and in supply and demand balance houre. If the supply pressure or supply flow is constant, the hydraulic parameters under various conditions were simulated to obtain the nodal flow and pressure curve. Then according to the simulation results, this paper analyzes the operation rules of the pipeline network system, and put forward reasonable management suggestions of operation and scheduling.The results and conclusions through network simulation are as follows:① The network hydraulic model based on MATLAB can be used to design pipeline network, simulate the pipeline network operation, and even economic simulation. It can be widely and practical used, and the operation is simple and fast convergence speed.② This paper study various gas users rule, and used nonuniform coefficient method to establish the natural gas predicted load model of the city, and forecast the gas flow in the peak time or low time in 2020 are 104.2129×104m3/h or 29.1391×104m3/h to enhance the accuracy of load calculation.③ This paper use the network hydraulic model to simulate the natural gas high-pressure pipline ring of a city, and get the pressure diagram under different conditions. Whether it is peak hour, low hour, or in the balance of supply and demand, No.2 node is the lowest pressure point, and the C district which is supplied by No.2 node may be a gas shortage area. The pressure of No.5 node is lowest among gas supply point. No.2 and No.5 node should be the focus of monitoring points, to avoid the shortage of gas or insufficient pressure.④ The pressure and flow of adjacent gas scroce in multi-source gas pipeline network system will influence each other. In the nature gas high-pressure ring pipline network of the city, No.5 and No.6 node are from the same long-distance transport pipeline, so it sould be considered that reduce the No.6 node supply flow and increase the No.5 node supply flow so that No.5 node have enough gas to provide No.2 and No.3 node.