Review of strategies to improve the efficiency and replace of indirect water bath heaters in city gate stations

Natural gas is usually depressurized through various stages before final consumption. In this process, city gas reduction stations (CGS) play an important role in regulating the gas pressure. Due to the Joule-Thompson effect, the pressure drop causes the gas temperature to decrease and increases the risk of hydrate formation. To avoid this phenomenon, indirect water heaters (IWBH) are used to preheat the gas. However, these heaters have low efficiency (often less than 40 %) and cause significant energy loss. This article comprehensively reviews the strategies to improve the performance of IWBHs. Among the most important of these strategies are optimizing the operating conditions using intelligent control systems, modifying the geometric structure, using nanofluids, increasing turbulence in the heat flow, recovering waste heat, using pressure energy with turboexpanders, and integrating combined heat and power (CHP) systems. The potential of using renewable energies such as solar and geothermal energy to provide the required heat has also been investigated. The findings show that these solutions can lead to energy savings of up to 74 %, an increase in thermal efficiency of up to 88 %, a significant reduction in pollutants and a return on investment in less than two years. Therefore, optimizing the performance of CGS heaters is fully justified not only from a technical point of view but also from an economic and environmental perspective.