CO₂ water-lean capture: Mathematical modelling and analysis of the industrial process

The most mature post-combustion capture technology is absorption of CO₂ into monoethanolamine (MEA). Typically, this process utilizes a solution of 30wt.% aqueous MEA as absorbent liquid; however, recent studies showed how increasing MEA concentration enhances mass-transfer coefficient in absorption columns. This work investigates effect of MEA concentration on the overall process. The main focus is given to regeneration heat. Heat duty at the reboiler per unit of recovered CO₂ (HDUC) is utilized as the primary performance indicator. The analysis employs an Aspen HYSYS® model. Increasing MEA concentration reduces HDUC by 74% when MEA concentration goes from 30wt.% to 90wt.%. Another parameter affecting HDUC is stoichiometric ratio between moles of MEA and CO₂. Halving molar ratio between MEA and CO₂, at 30 wt.% MEA concentration returns a reduction in HDUC of 48%, while at 90wt.% MEA concentration, the observed reduction is 9%. Overall, increasing MEA concentration improves process efficiency.