Abstract: In natural gas gathering and transportation process, the throttling expansion refrigeration and low temperature separation method is one of the most common technology. The condensation is a key issue during the throttling flow, as the temperature after throttle is the main influence factors of dew point. With the field data of throttling separation technology, uniform model for homogeneous and heterogeneous condensation is established to study the natural gas throttling condensation process. Four hydrocarbon components (n-pentane, n-hexane, n-heptane, n-butane) are chosen as the objects of study. The effects of back pressure ratio and inlet total temperature on the condensation properties of different hydrocarbon components are analyzed. It is shown that, the flow field in the throttle is extremely complex, and intense turbulent flow characteristics are presented. In the natural gas throttling process, extremely low temperature is obtained which provides the suitable condition for condensation of the hydrocarbons. With increase of back pressure ratio and total temperature, the condensation mass fraction and droplet size of each condensable component decrease. Great differences of condensation parameters are found among each component. For the lighter hydrocarbon components, the condensation mass fraction is greater, and the condensation mass fraction and droplet radius of which are much more affected by the back pressure ratio and inlet total temperature.

Key words: Condensation, Natural gas, Throttling