Measurement of the water solubility in the gas phase of the ethane plus water binary system near hydrate forming conditions

This project involves measurements of the vapor phase composition for the ethane + water binary system presenting phase equilibria near hydrate-forming conditions. The H2O + C2H6 binary system isothermal vapor phase data, concerning both vapor-liquid and vapor-hydrate equilibria, were measured at (278.08, 283.11, 288.11, 293.11, 298.11, and 303.11) K and pressures up to the ethane vapor pressure. In this work a static-analytic apparatus, taking advantage of a pneumatic capillary sampler (Rolsi, Armines' patent) developed in the Cenerg/TEP laboratory, is combined with an exponential dilutor for calibration purposes and a PVT apparatus to visualize and determine the hydrate-forming conditions. The six sets of isothermal P, y data are represented with the Peng-Robinson equation of state (PR-EoS) using the Mathias-Copeman alpha function and the Huron-Vidal mixing rules involving the NRTL local composition model (PR-EoS/MC-HV-NRTL). This equation (PR-EoS/MC-HV-NRTL) is also used to fit the available literature data. A Henry's law approach was selected to treat the aqueous phase.