Energy recovery from mechanical energy of high-pressure natural gas pipeline: a case study simulation

Abstract The gas distribution system is a network designed to deliver natural gas (NG) from production to end users. A very high pressure is maintained at the production site to ensure efficient transportation through the pipeline system. It must then be depressurized at the point of consumption, typically through several stages. A significant amount of energy is wasted during the depressurization of NG at city gas stations (CGS), where throttling is employed. The pressure in the gas distribution system at many depressurization gates ranges from 400 to 700 psi. The problem is that a steep decline in temperature occurs while throttling resulting in NG hydrate formation due to the presence of water vapor in the stream. NG hydrate has been of importance for energy storage. However, it may cause disasters in gas pipelines during throttling in CGS. Therefore, removing the hydrate structure is vital to prevent the stream from blockage, for which large heaters are being used. The available kinetic energy within the flowing stream can be a source of heat to preclude hydrate formation. In this article, a simulation study is presented according to Birjand CGS measured data. The results show that during winter, almost 90 percent of the required energy for preheating can be produced using the NG high-pressure mechanical energy.