251528 Modeling of CO2 Absorption In and Stripping From Aqueous Amine, Amino Acid and Carbonate Blends
An approximate analytical method based on steady-state Film Theory has been demonstrated to enable accurate, computationally efficient prediction of carbon dioxide absorption and desorption rates in packed columns. The method is based on a particular scheme for linearizing the coupled differential equations that govern steady-state diffusion with multiple reversible reactions. Interphase transport rates calculated based on Film Theory agree closely with those obtained via exact numerical methods. Notably, the same accuracy is observed whether the reactions are fast or slow; when their characteristic times differ by orders of magnitude; and irrespective of the magnitudes of transport and reaction driving forces. The method was recently applied [Meldon and Morales-Cabrera, Chem. Eng. J., 2011, 171, 753] to the analysis of carbon dioxide absorption in and desorption from aqueous solutions of monoethanolamine, prior modeling of which had relied for accuracy on numerical methods of analysis. It is extended here to carbon dioxide capture with aqueous solutions of blends of amines, amino acids and alkali. The relative merits of candidate scrubbing solutions, for purposes of flue gas CO2 capture at coal-fired power plants, are evaluated based on interphase transfer rates, rich and lean loadings, and stripper reboiler duties.