Modelling and prediction of the solubility of acid gases in diethanolamine solutions

The pseudo-equilibrium model proposed by Kent and Eisenberg is used in this study to model the absorption of acid gases (H 2 S and CO 2 ) in aqueous diethanolamine solutions at equilibrium. A wide range of experimental data available in the literature is used to obtain the values of the pseudo-equilibrium constants of the amine reactions. These data cover amine concentrations from 0.5 to 8 N, temperatures from 273 to 413 K, and acid gas loadings from zero to unity. New correlations for the pseudo-equilibrium constants and solution pH are obtained as a function of temperature, amine concentration, and acid gas loading for loading up to unity. The partial pressure of H 2 S is much better predicted by the new correlation compared to the work of Kent and Eisenberg. The predictions of the partial pressure of CO 2 are improved mainly at high temperatures and amine concentrations.