Improved Kent-Eisenberg models for predicting H2S and CO2 solubilities in aqueous TEA solutions

摘要

Absorption of acid gases (H2S and CO2) through using alkanolamine solvents is widely used in the gas sweetening process. Gas treating plants are now forced by the environmental authorities to maintain a certain low level of H2S and CO2 concentrations in their sales gas. Therefore, it is important to study the acid gas vapor - liquid equilibrium (VLE) in alkanolamines in order to achieve the needed sweet gas specifications. (Posey et al., 1996) [6] was able to derive a simple model that predicts single or mixed acid gas systems solubility in aqueous methyldiethanolamine (MDEA) and diethanolamine (DEA) solutions. This model can be considered as a good initial guess for other complex equilibrium calculations. Also, (Patil et al., 2006) [5] derived a model that predicts single or mixed acid gas systems solubility in aqueous MDEA solutions through the dissociation of the protonated alkanolamine equilibrium constant. This paper extends Posey's regression to form a simpler model for calculating the dissociation of the protonated triethanolamine (TEA) equilibrium constant. The model can be used to correlate mixed acid gases solubility data over 2, 3.5 and 5 M of aqueous TEA solutions at 50, 75 and 100 °C. New parameters were regressed for (Posey et al, 1996) [6] model to be able to predict the aimed (TEA - H2O - H2S - CO2) system. Results for the new extended model showed the ability to predict CO2 partial pressures accurately while predicting that of H2S with a higher percent error.