Feasibility Study of Pressure Letdown Energy Recovery from the Natural Gas Pressure Reduction Stations in South Korea

한국의 천연가스 도시정압기지에서 감압에너지 회수에 대한 타당성 연구

Yoo, Han Bit;Hong, Seongho;Kim, Hyo

  • Received : 2015.04.17
  • Accepted : 2015.05.29
  • Published : 2015.06.28


Almost all of the natural gas consumed in South Korea is compressed into very high pressure for the transportation through the underground pipelines, then reduced in pressure regulation stations before delivery to the consumer. For pressure reduction, expansion valves have been used due to the simple and effective installation, but recover none of the energy in the gas during compression. Hence, turbo-expanders are proposed instead of the valves to accomplish the same pressure letdown function and recover some of the compression energy in the form of shaft work converting into electric powers. Here we have theoretically calculated the electric powers at the pressure reduction from 68.7 bar to 23 bar (which are the average values taken at the inlet and outlet points of the expansion valve in medium-pressure regulation stations) according to the inlet conditions of temperature and flow rate. The natural gas is considered as two cases of a pure methane and the mixture of hydrocarbons with a very small amount of nitrogen, and the Peng-Robinson equation of state is employed for the calculation of required thermodynamic properties. The electric energy is recovered as much as 1596 MW(methane) and 1567 MW(mixture) based on the total supply of natural gas in 2013.


natural gas;turbo-expander;pressure reduction;energy recovery;thermodynamic properties


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Supported by : 서울시립대학교