Hydrate-containing phase equilibria for mixed guests of carbon dioxide and nitrogen

Hydrate-containing phase equilibria for mixtures composed of carbon dioxide, nitrogen and water are of potential importance for the flow assurance in the transportation of captured carbon dioxide. Literature data for such mixture tend to be reported on water free basis. In this study three- and four-phase equilibria were experimentally studied at the pressure ranging from 5 to 20 MPa. Isobaric dissolution temperatures of formed hydrates were measured and reported for accurately determined loading compositions. Complex phase behaviors composed of two-, three- and four- phases were observed and they were analyzed by comparing with calculations using GSMGem program developed by Sloan and Koh [1]. Phase equilibria were found to be sensitive to water contents in water dominating mixtures. CSMGem and HYSYS (version 7.1) from AspenTech calculations were found in general agreements with present and literature data.

► 3- and 4-phase equilibrium for CO2–water–N2 system with hydrates was measured.
► Complex phase behavior was analyzed with experimental data and CSMGem.
► Complex phase behavior was discussed in ternary diagram.