Mass Transfer Modelling for Compact Hybrid Membrane-Absorption Processes in Removal ofC02 from Natural Gas

The removal CO2 from natural gas has been the target for many gas
processing industries. This is due to its importance for increasing the calorific value
of natural gas (NG) and increasing the pipeline lifetime since CO2 is having
corrosive properties.
The main objective of this work is to model and predict the mass transfer for
the compact hybrid membrane-absorption processes. A simulation model was
developed using MathCad which able to predict the CO2 transport across membrane,
followed by absorption to amine solution.
The overall mass transfer coefficient at the membrane and liquid side was
analyzed by varying the operating parameters such as the pressure and the
temperature of the process. The membrane characteristics such as the pore size,
membrane thickness, porosity and tortuosity are also considered in studying the
mass transfer of CO2. The significant value of overall mass transfer coefficient in the
study signifies and shows that separation is very favourable for compact hybrid
system.
Generally, the overall mass transfer coefficient for the compact hybrid
membrane-absorption processes was found to decrease as the operating temperature
increased. The overall mass transfer coefficient increases when the operating
pressure increased. However, the increase in membrane thickness would reduce the
overall mass transfer coefficient. In addition, when the porosity of the membrane
increases, the overall mass transfer coefficient gradually increased. Lastly, the best
operating condition for the compact hybrid membrane-absorption processes is in the
region of low temperature between 300K and 400K and in the region of high
pressure between 10 bar to 30 bar. In this range, the magnitude of the overall mass
transfer coefficient is in the magnitude of 10"6 which is comparable with other
researchers work such as the study and model developed by Li and Teo (1996).