A thermodynamic model for gas hydrates in the presence of salts and methanol

The equation of state (EOS) for aqueous electrolyte solutions developed by Furst and Renon (1993) has been extended to predict vapor-liquid equilibria (VLE) of ternary water-methanol-salt systems. The model parameters have be en determined by fitting only binary data and related to the cationic Stoke s diameters. The predictions of vapor-liquid equilibria of ternary water-me thanol-salt systems are in good agreement with the experimental data. Then the extended EOS has been utilized to develop a predictive method for gas h ydrate formation conditions in the presence of electrolytes and methanol. T he new hydrate method employs the Barkan and Sheinin (1993) hydrate model f or the description of the hydrate phase, the extended EOS for the vapor pha se fugacity and for the activity of water in the aqueous phase. The agreeme nt is good between the predicted hydrate formation pressures and experiment al data.