Abstract: With the widespread application of natural gas and the continuous development of related technologies, the transmission pressure of natural gas pipe networks is becoming higher and higher , resulting in the accumulation of tremendous pressure energy. In order to make full use of the pressure energy of natural gas and solve the ice blocking produced by pressure drop in the mining process, a scroll high-pressure gas expander(SHGE) of natural gas wellhead is designed which can use its own pressure energy for power generation and prevent ice blocking. The operation principle and structures of SHGE are discussed in detail, then the force and work process according to aerodynamics and engineering thermodynamics on rotating body, thermodynamics process is expressed in h-s diagram, and the equations for the relevant parameters of thermodynamics process are obtained. Finally working capacities of SHGE are calculated with some examples under different conditions. The results provides a basis for establishing a complete design theory for SHGE.

Key words: Aerodynamics, Ice blocking, Pressure energy, Scroll high-pressure gas expander, Thermodynamics process