(653b) Water Solubility in Supercritical Carbon Dioxide and Its Effect On Gas Phase Density

Phase behavior of CO2-H2O system has been a subject of interest in many fields of science and engineering. CO2 injection based enhanced oil recovery methods, CO2 sequestration in saline aquifers and abandoned hydrocarbon reservoirs, and treatment of waste waters contaminated with dissolved acid gases are some of the subjects dealing with the thermodynamic behavior of the CO2-H2O system. Most of the studies on CO2-H2O system are devoted to the low to moderate pressure and temperature conditions. Only a few studies are dedicated to the high pressure and high temperature conditions.

Due to the paucity of experimental data at such conditions, a series of experiments have been conducted from 423 K to 478 K over a wide range of pressures from 3.8 MPa to 110 MPa. The solubility of water in carbon dioxide as well as the vapor phase density are measured. In order to measure the mass of water and volume of gas in the vapor phase, in each experiment the vapor phase of a L-V equilibrium system is transferred to an equilibrium flash separator equipped with a desiccant and a gasometer. The gas volume is converted to the mass and density based on the ideal behavior of gases at standard conditions.

A comparison between the new generated water solubility in CO2 data and literature data shows that despite the similar trend observed between the Tödheide and Franck[1] data and present data, at the same experimental conditions, lower concentrations of water in the vapor phase are measured in this work. However, the Gillespie and Wilson[2] low pressure data are in good agreement with the new experimental data. There is no consistency between the Takenouchi and Kennedy[3] data and generated data in this work.

The produced data for vapor phase density in this study accurately follow the characteristic trend. Due to the interconnectivity between density data and water content data in the designed experimental procedure, it is believed that the new water content data obtained in this experimental study are reliable.

References:

1. Todheide, K., Franck, E. U., (1963). "Das Zweiphasengebiet und die Kritische Kurve im System Kohlendioxid + Wasser bis zu Drucken von 3500 bar." Z. Physik. Chem. Neue Folge., 37: 387-401.

2. Gillespie, P.C., Wilson, G.M. (1982). "Vapor-liquid and liquid-liquid equilibria: water-methane, water-carbon dioxide, water-hydrogen sulfide, water-n-pentane, water-methane-n-pentane. GPA Research Report RR-48.

3. Takenouchi, S., Kennedy, G. C., (1964). "The Binary System H2O-CO2 at High Temperatures and Pressures." American Journal of Science, 262: 1055-1074.