VLE modelling for aqueous systems containing methyldiethanolamine, carbon dioxide and hydrogen sulfide

A method is proposed for modelling vapor–liquid equilibria in ternary aqueous systems containing acid gas and alkanolamine with an equation of state describing both phases. A hole quasichemical model is modified with due regard for chemical reactions and electrostatic interactions in the liquid solution. The modelling was carried out for the carbon dioxide–N-methyldiethanolamine (MDEA)–water and hydrogen sulfide–MDEA–water systems in the temperature range from 313 to 413 K at pressures up to 5 MPa and amine concentrations up to 4 mol/kg of water. Satisfactory agreement with the experimental data was obtained.