Integration of CO2 capture unit with membrane distillation technology: CO2 mitigation and freshwater production

Abstract

The severe consequences of carbon dioxide (CO2) emissions into the atmosphere and a dire need for freshwater are among the biggest global challenges. The desire to meet these challenges has given rise to the motivation of proposing a direct contact membrane distillation (DCMD) technology integrated with the CO2 capture unit to mitigate CO2 and simultaneously produce freshwater. The CO2 capture unit has been modeled with Aspen Plus® V.10 and for the DCMD system, MATLAB software was adopted. MATLAB software was not linked to the Aspen Plus®. Thermal heat contained in both the purged gas and leanout stream was recovered by using a DCMD unit. A blended solution of methyldiethanolamine (MDEA) and piperazine (PZ) was considered as an absorbent to remove CO2 from the flue gas of a large-scale coal-fired power plant (650 MWe). About 85 % of the CO2 in the flue gas has been captured from the top of the stripper column. At MDEA/PZ (concentration ratio of MDEA and PZ in the aqueous solution) concentration of 30/20 wt.%, a reboiler duty of 3.27 MJ/kg CO2 was obtained. Freshwater was produced at a rate of 25.43 m3/day from DCMD unit 1 and 1428.19 m3/day from unit 2.