SIMULTANEOUS ABSORPTION OF CARBON-DIOXIDE, CARBONYL SULFIDE AND HYDROGEN-SULFIDE IN AQUEOUS METHYLDIETHANOLAMINE

In this work the simultaneous absorption of two and three acid gases in a tertiary amine, methyldiethanolamine (MDEA), is studied theoretically and experimentally. Two cases were considered, the absorption of CO2 and COS in MDEA and the absorption of CO2, COS and H2S in MDEA. A film model for the liquid phase is used to calculate the enhancement factors for individual gases. For the case of H2S absorption it was necessary to model the gas phase mass transfer resistance. Experiments were conducted in a stirred cell absorber operated at steady state conditions. Experiments were carried out for a range of MDEA concentrations (10-50 wt%) and stirrer speeds. The experimental absorption rates agree well with model predictions with absolute mean deviations in all cases less than 14%.