Process simulation and optimal design of membrane separation system for CO2 capture from natural gas

In recent years, membrane gas separation has emerged as an alternative of other available technologies (such as absorption an
d
cryogenic separation) in order to
remove CO
2
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 CO
2
contents and high pressure, and thus potentially causes condensation across the
membrane. It may be preven
ted 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 co
ndensation in the membrane.