Compositional Analysis and Hydrate Dissociation Conditions Measurements for Carbon Dioxide + Methane + Water System

Abstract

Publication Date (Web): March 24, 2011International audienceA detailed description of an experimental setup based on the "static-analytic" technique with gas phase capillary sampling designed, built, and improved "in-house" to measure phase equilibria (pressure, temperature, and compositions) under gas hydrate formation conditions is presented in this work. The apparatus is suitable for measurements at temperatures ranging from 233 to 373 K and pressures up to 60 MPa. It was used to study phase equilibria in the carbon dioxide + methane + water system under hydrate formation conditions. An isochoric pressure-search method was used to measure hydrate dissociation conditions. The experimental data have been compared successfully with the literature data. The compositions of the gas phase in equilibrium with the hydrate and aqueous phases were measured using a gas chromatography technique and compared successfully with the literature data. The compositions of the hydrate and aqueous phases were determined by applying material balance equations. The experimental data on the compositions of the hydrate have been compared successfully with the literature data. To solve the latter equations, the Newton's numerical method coupled with the differential evolution optimization strategy was employed. All the aforementioned experimental data (hydrate dissociation conditions + composition analyses) have been compared with the predictions of two thermodynamic models, namely CSMGem and HWHYD. A discussion is made on the reliability of the predictions of the latter models

Investigation of CO2 separation from synthesis CO2/CH4 mixture utilizing tetra‐n‐butyl ammonium bromide semi‐hydrate

“…Acosta et al found that, with CO 2 /CH 4 gas mixtures (0.4/0.6 and 0.6/0.4), the pressure required to form semi‐clathrates at a given temperature decreased as the TBAB concentration increased. Mohammadi et al measured and reported the clathrate/semi‐clathrate hydrate formation and dissociation conditions for systems containing CO 2 /CH 4 mixtures in the presence of pure water and different mass fractions of TBAB aqueous solutions. A significant decrease in the operating pressure was observed during gas hydrate formation for separation of CO 2 from the corresponding gas mixtures due to the hydrate promotion effects of TBAB.…”

Hydrate phase equilibrium for CH4‐CO2‐H2O system in porous media

“…In other words, the crystalline and thermodynamic properties can vary significantly from those of hydrate formed from pure gases based on the combination and ratio of hydrate formers . Thus, the phase equilibrium conditions of CO 2 /CH 4 gas mixture have been studied by many researchers . By employing the isobaric temperature search method, Seo et al acquired three‐phase equilibria data for the CO 2 ‐CH 4 ‐H 2 O system .…”

“…[1,16] Thus, the phase equilibrium conditions of CO 2 /CH 4 gas mixture have been studied by many researchers. [17][18][19][20][21][22][23] By employing the isobaric temperature search method, Seo et al acquired threephase equilibria data for the CO 2 -CH 4 -H 2 O system. [24] The solubility of methane and CO 2 under equilibrium conditions of hydrate, liquid water, and vapour was measured, and the effect of pressure on the equilibrium mole fraction of respective hydrate formers in the liquid was discussed by Bruusgaard et al [25] CO 2 /CH 4 gas mixture hydrate formation with and without THF were investigated by Lee et al, who found that the CH 4 /CO 2 (50:50) gas mixture hydrate formed the s-I hydrate, instead of the s-II hydrate formed by the THF þ CO 2 /CH 4 gas mixture.…”

Continuous separation of CH4/N2 mixture via hydrates formation in the presence of TBAB

“…Hydrates have the potential for many industrial applications: flow assurance in petroleum industry [13][14][15][16], CO 2 capture and sequestration [17][18][19][20][21][22], separation of close-boiling point compounds [23][24][25], water desalination [26], gas (H 2 and CH 4 ) storage [27][28][29], refrigeration and cool storage [30][31][32].…”