Phase equilibria of CO2+N2 and CO2+CH4 clathrate hydrates: Experimental measurements and thermodynamic modelling

Experimental dissociation conditions for clathrate hydrates of carbon dioxide + nitrogen are reported in the (278.1 to 285.3) K and (3.24 to 29.92) MPa ranges, which were measured using an isochoric pressure search method. The relative molar composition of carbon dioxide and nitrogen in the feed gas, varying between (0.271 and 0.812), were measured by gas chromatography technique. A thermodynamic model based on the Cubic Plus Association equation of state for fluid phases combined with the van der Waals and Platteeuw solid solution theory for the hydrate phase is presented herein. The dissociation data generated in this work along with the experimental data reported in the literature for carbon dioxide + nitrogen and carbon dioxide + methane hydrates are compared with the results of this model and also with the predictions of two other thermodynamic models, namely HWHYD and CSMGem. A discussion is made about the deviations observed between experimental and predictions. (C) 2012 Elsevier Ltd. All rights reserved.