Effect of absorption enthalpy on temperature-swing CO2 separation process performance

We model a CO2 absorption process to elucidate the rationale for the search for a solvent with an enthalpy of absorption (ΔH) of low magnitude. We explore the relationship between ΔH and the system’s performance. While in general a lower magnitude appears to provide better system performance because it permits the stripper temperature to be decreased, as the magnitude drops below its value for monoethanolamine amine (MEA), 80 kJ/mol, the required solvent mass flow rate must increase precipitously and/or the flue gas must be cooled significantly. We argue that the associated parasitic pumping and cooling loads, as well as the increased capital cost, may set a practical lower limit on the magnitude of the enthalpy of absorption that is not very different from that of MEA.

Engineering and Applied Sciences