Amine screening for flue gas CO2 capture at coal-fired power plants: Should the heat of desorption be high, low or in between?

Researchers worldwide have been measuring properties of amine-based scrubbing solutions, seeking alternatives to aqueous monoethanolamine that will reduce the costs of flue gas CO2 capture (FGCC). Because the operating costs of FGCC are closely tied to the stripper reboiler duty (QReb), many laboratories have been screening for low heats of desorption, ΔHDes. Recently, their logic was challenged on the grounds that QReb has three components, one of which is greater when ΔHDes is higher, another of which is greater when ΔHDes is lower. This paper supports that argument and concludes that the complex dependence of QReb on ΔHDes, and on other amine properties, makes process simulation a necessary adjunct to rational amine screening.

► The reboiler duty, QReb, is a major expense in flue gas CO2 scrubbing with standard aqueous monoethanolamine (MEA).
► The practice of screening alternatives to MEA for low heats of desorption, ΔHDes, is ill-advised.
► A low ΔHDes minimizes one contribution to QReb while maximizing another.
► The optimal ΔHDes depends on operating conditions and accessibility of power plant steam and electrical power.
► Rigorous evaluation of prospective amines requires a process simulator.