Phase equilibria of R22 (CHClF2) hydrate systems in the presence of NaCl, KCl, and MgCl2

Abstract

The three-phase (hydrate-aqueous liquid-vapor) equilibria of the R22 (CHClF2 = chlorodifluoromethane) hydrate forming systems in aqueous solutions containing NaCl, KCl, and MgCl2 were measured at pressures ranging from 0.140 to 0.790 MPa, temperatures between 273.9 and 287.8 K, and several compositions of each electrolyte. The upper quadruple points (hydrate-liquid R22-aqueous liquid-vapor) were also measured at each electrolyte concentration. The addition of electrolytes to the aqueous solutions caused inhibition of the hydrate formation. A thermodynamic model that predicts the three-phase hydrate equilibria was developed. The inhibiting effect of electrolytes was accounted for using a Pitzer model. A van der Waals and Platteeuw model and Redlich-Kwong-Soave equation of state with a modified Huron-Vidal mixing rule were used. The calculated results were found to be in good agreement with the experimental data.