Representation of Hydrate Phase Equilibria in Aqueous Solutions of Methanol and Electrolytes Using an Equation of State

Abstract

In this work, the method for the calculation of hydrate phase equilibria proposed by Zuo and Stenby (Zuo, Y.-X.; Stenby, E. H. SEP 9816. J. Soc. Petr. Eng., submitted) has been extended to represent incipient equilibrium hydrate formation conditions in aqueous solutions containing methanol and electrolytes. To predict hydrate formation conditions, the parameters of the extended Furst-Renon electrolyte equation of state (Furst, W.; Renon, H. AIChE J. 1993, 39, 335−343) have been reevaluated. Interaction parameters between water and methanol have been determined to match experimental hydrate formation data of methane in the water−methanol solutions. The interaction parameters between methanol and ions are associated with cationic Stokes and anionic Pauling diameters. Furthermore, cationic Stokes diameters in methanol are assumed to be a function of temperature. Coefficients of the temperature dependence have been determined by two methods. In method I, the cationic Stokes diameters in methanol are equal to ...