Approximate simulation of CO₂ and H₂s absorption into aqueous alkanolamines

Rigorous and approximate methods are compared for the simulation of CO 2 absorption into aqueous alkanolamine mixtures of methyldiethanolamine and diethanolamine. In addition, data for the mixtures containing monoethanolamine and the simultaneous absorption of CO 2 and H 2 S are presented. For the rigorous approach, the simplified eddy diffusivity theory is used to simulate the liquid‐phase hydrodynamic characteristics. The approximation methods examined are the pseudo‐first‐order approximation, the interpolation approximation of Wellek et al. (1978), the algebraic combined flux (ACFLUX) approximation and the modified combined flux (MCFLUX) approximation. The latter approximation utilizes the reaction zone concept to determine the kinetic preference of the absorbing gas at the gas‐liquid interface. Under the range of conditions studied, the MCFLUX approximation predicts very accurately the CO 2 and H 2 S flux rates in mixed amine systems, as compared with the rigorous solution of the differential equations.