Simulation of CO2 removal from pressurized natural gas stream contains high CO2 concentration by absorption process using membrane contactors

Despite the importance of natural gas (NG) as an energy source, there is a lot of pressurized landfill gas not exploited so far because it contains high CO2 concentration. Therefore, this study aimed to develop a 2-D mathematical model to simulate CO2 removal from NG stream contains high CO2 concentration up to 70% at high-pressure up to 60 bar using three different dimensions of polyvinylidene fluoride (PVDF) hollow fiber membrane contactors. Aqueous solutions of activated methyldiethanolamine (MDEA) with piperazine (PZ) were adopted. The performance of considered absorbent at high-pressure was evaluated at the non-wetting mode condition of membrane contactor. Moreover, the effect of pressure, contact area, gas flow rate, MDEA concentration into the amine mixture, PZ concentration, temperature and membrane properties were theoretically investigated. The findings stated that activated MDEA had different performance in terms of membrane wetting compared with other amines, which used at high pressure in previous studies. In addition, the simulation results showed that CO2 removal efficiency was significantly enhanced, when the operating pressure, contact area, PZ concentration and temperature were increased. However, increasing gas flow rate leads to reduce CO2 removal efficiency. Furthermore, the CO2 absorption was significantly improved by adding a small amount of PZ to MDEA. The predicted model results showed a good agreement with experimental data obtained from the literature.