Experimental vapor-liquid equilibriums in the carbon dioxide-diethylene glycol-water and carbon dioxide-triethylene glycol-water systems at feasible absorption temperatures and pressures

Abstract

The water contents of compressed carbon dioxide gas in equilibrium with diethylene glycol (DEG) solutions of 3.5 and 7.0 wt % water, and with triethylene glycol (TEG) solutions of the same concentrations, have been measured at temperatures of 23.89, 37.78, and 48.89 /sup 0/C, and pressures of 2.5166, 2.8955, and 5.2745 MPa. A comparison of the dehydration capabilities of the same glycol-water solution for CO/sub 2/ with that for natural gas (or methane) indicates that the dehydration qualities for the former (CO/sub 2/) exceed those for the latter on an absolute water content basis until a reversal occurs when the CO/sub 2/-rich phase begins to assume dense-fluid characteristics. The solubilities of carbon dioxide in the aqueous glycol solutions of the same concentrations and conditions as the water content measurements, and in the pure glycols, are also reported. The CO/sub 2/ solubility in TEG and DEG solutions has been analyzed thermodynamically by applying the Krichevsky-Kasarnovsky (KK) equation to both the glycol solutions and the pure glycols. The thermodynamically predicted data agreed with the experimental or smoothed experimental data to better than 2% for both the pure and aqueous solvents at temperatures ranging from 23.89 to 48.89 /sup 0/C. In the prediction,more » the experimental data and thermodynamically consistent low-pressure solubility data were used. Data were extrapolated to essentially zero pressure to deduce the isothermal Henry's law constants.« less