Increasing the Efficiency of Compressor Stations

of Main Gas Pipelines

Agha Rasulzada

Abstract. The recovery and utilization of waste heat from gas turbine engines (GTE) currently stand out as one of the most critical and pressing engineering challenges in the energy sector. This issue is particularly vital for the compressor stations of main gas pipelines due to the massive total installed capacity of the driving gas turbine units. Standard waste heat recovery systems, such as waste heat boilers or traditional gas turbine cycles, impose significant aerodynamic backpressure on the exhaust of the primary gas turbine engines. This backpressure reduces the available enthalpy drop across the power turbine, causing a substantial drop in the shaft power output. To compensate for this loss and restore the original compressor performance, operators must increase fuel consumption, which inherently degrades the overall thermodynamic and economic efficiency of the facility. To resolve this technological conflict, inverted-cycle gas turbine units (ICGTU) can be effectively implemented. In these specialized sub-atmospheric configurations, no additional backpressure is generated at the exhaust of the primary engine because the aerodynamic losses are successfully compensated for by the pressure rise inside the specialized utilization compressor. The thermodynamic process in an ICGTU operates uniquely: the hot exhaust gases from the primary engine enter the turbine first, expand below atmospheric pressure, flow through a gas-water cooler, and are subsequently compressed back to ambient atmospheric pressure. This study provides a comprehensive mathematical and thermodynamic analysis to determine the optimal pressure ratio ) for maximizing specific work and thermal efficiency. The implementation of an ICGTU can contribute an additional 15–25% to the total mechanical shaft power of the station. When integrated with a district or technological water heating system, the overall fuel utilization coefficient reaches an impressive 0.80–0.85, while simultaneously reducing specific hazardous emissions by 15–25% relative to the combined power output.

Keywords: Waste Heat Recovery, Combined Gas-Gas Cycle, Inverted-Cycle Gas Turbine, Thermal Efficiency, Gas Pipeline Compressor Stations