The Study of Joule Thompson Effect for the Removal of CO2 from Natural Gas by Membrane Process

In recent years, membrane gas separation has emerged as an alternative of other available technologies (such as absorption and cryogenic separation) in order to remove CO2 from natural gas. A common phenomenon during gas separation by membrane is the occurrence of Joule-Thomson (JT) effect. The temperature may change to a large extent dependent on the type of gas and the pressure applied. In turn, this temperature change may have a large influence on the permeation properties. Moreover, feed gas may condense due to sudden expansion caused by the decrease in pressure while permeating through the membrane. The effect of different parameters on the temperature change due to JT effect has been investigated under the present study. It is shown that the temperature drop is quite significant for feed gas with high CO2 contents and high pressure, and thus potentially causes condensation across the membrane. It may be prevented by achieving a predetermined dew point before the membrane and then heating the gas to provide a sufficient margin of super heat. This increase in temperature increases the margin between the gas dew point and operating temperature and thus prevents condensation in the membrane.