Phase equilibrium condition measurements in carbon dioxide hydrate forming system coexisting with sodium chloride aqueous solutions

Abstract Three phase equilibrium conditions of (sodium chloride aqueous solution + carbon dioxide hydrate + vapour carbon dioxide) were measured to establish seawater desalination technology using clathrate hydrates. The three phase equilibrium condition measurements were performed at temperatures between 271.85 K and 279.05 K, and at pressures between 1.283 MPa and 3.617 MPa. The concentrations of sodium chloride aqueous solution were 0.0350, 0.0700, 0.1000, and 0.1050 in mass fraction. It was found that the equilibrium temperature difference between pure water system and each sodium chloride concentration system at the same pressure was hardly influenced by the pressure level. In addition, it was found that the equilibrium temperature depression of carbon dioxide hydrate by the addition of sodium chloride is smaller than that of ice and cyclopentane hydrate especially at the high concentration of sodium chloride.