Nasim Etemadee - Department of Mechanical Engineering, Semnan University
S Saedodin
Arash Mohammadzadeh

Reducing the pressure of natural gas in city gate station will cause cooling around pressure reducer valve and so this help to formation gas hydrate in pipeline. In factlow temperature, existing water in pipeline and the presence of hydrate ingredients such as methane, ethane, and carbon dioxide…cause this process. Gas hydrate in gastransmission pipelines will prevent transmission of gas and the pipeline will be blocked. So we should prevent the formation of gas hydrate, because the costs ofpipeline blockages due to hydrate formation are high. One method for preventinghydrate formation is temperature control that with heating gas can be prevented from reaching the point of hydrate formation. In this paper the temperature changes duringthe process of reducing gas pressure are calculated. Compressibility factor of natural gas are calculated according to the temperature of natural gas and assumption thatthe natural gas is real gas and with equation of state. Then the enthalpy of natural gasand heat losses are calculated with this information. For calculating the enthalpy of the gas mixture, we developed a numerical method and a computer program. We haverun program for a CGS regulator. Finally the results are presented as graphs.

Pressure reducer valve, temperature, compressibility factor, enthalpy, natural gas