Equilibrium Approach for CO2 and H2S Absorption with Aqueous Solutions of Alkanolamines: Theory and Parameter Estimation

Acid gas, removal from gas streams is mainly executed industrially via aqueous' alkanolamines absorption, whose modeling Often involves, :ionic nonequilibrium chemical reactions,: and mass/heat interfacial transfers. This demands high computational efforts and often nonavailable physicals parameters. Also, the role of ions,, created by weak dissociations, is not well understood, and despite the high pressures; concentrations, and loadings, idealities, are often recruited, such as ideal laws for gas and mass action. In this work, these issues are circumvented by prescribing only molecular species incorporated into a chemical theory equilibrium framework using full thermodynamics via cubic equations of state. Nonvolatile molecular Complex species are formed via equilibribm, reactions involving acid gas, water, and alkanolamines (AGWA) systems. The approach is calibrated with large sets of AGWA data, partial pressures, and loadings, by searching equilibrium constants via maximum likelihood nonlinear implicit parameter estimation. These constants are used to address ideal gas properties of Complex species, which are necessary to model energy effects in AGWA separations.