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Power recovery in a gas pressure reduction station using 3D CFD modeling of a twin screw expander
Author(s): Hormoz Abolhasani, Mahdi Moghimi, Mahmood Ebrahimi
Keywords: Twin screw expander; City gate station; CFD; Exergy analysis
The limitation of energy resources in the world has raised attention in finding new resources of clean energy and identifying methods for recovering of exergy losses. Twin screw expander (TSE) is one of the positive displacement machines that can be used to recover mechanical power from fluids, which is taken into consideration in recent years due to lower installation, operation and maintenance costs in comparison with common expansion turbines (CET). In this paper, technical and economic conditions of a city gate station (CGS) was studied with the aim of recovering exergy loss using a TSE. A computational fluid dynamic code was used to simulate the three-dimensional fluid flow in the TSE. The simulation results for Shahroud station, a CGS located in the east of Iran, show that, unlike CET, flow and pressure fluctuations in different seasons of the year do not cause any restrictions on the use of TSE and 85.3% of annual loss exergy is recovered by this machine. Economic studies show that the internal rate of return (IRR) and payback period of TSE utilization are respectively 27.6% and 4.4 years, which makes it particularly attractive for investment in CGS stations compared to the CET.