Phase Equilibria of Clathrate Hydrates of Ethyne + Propene

Abstract

In the present study, experimental incipient dissociation data obtained by the isochoric pressure search method for mixed ethyne and propene (0.189, 0.544 and 0.846 mol fraction of ethyne) hydrates are reported in the temperature and pressure ranges of (275.9 to 283.4) K and (0.651 to 1.827) MPa, respectively. Additionally, three-phase equilibrium conditions inside the hydrate stability region were measured in the temperature and pressure ranges of (273.4 to 282.6) K and (0.441 to 1.709) MPa, with compositional analysis. Experimental ethyne mole fractions at equilibrium on a water-free basis ranged from 0.080 to 0.856. The van der Waals and Platteeuw solid solution theory, with the Valderama–Patel–Teja equation of state and nondensity dependent mixing rules were used to model the hydrate dissociation conditions of the ethyne + propane + water system. Good agreement was found between experimental data and predicted values.

Phase Equilibria of Clathrate Hydrates of Ethyne + Propane

“…The modeling approach used in this study has been detailed previously. 52 It relies on the equality of fugacity for each component in all three coexisting phases. The Valderrama modification of the Patel and Teja equation of state 45 and the nondensity-dependent mixing rules 46 allowed calculation of the fugacity of water and that of hydrate formers (ethyne and propane) in the fluid phases.…”

“…Hydrate dissociation conditions were experimentally determined by means of the isochoric pressure search method. − Care was taken to first wash the equilibrium cell with deionized water. Before the materials of interest were loaded, the cell was dried, immersed in the temperature-controlled ethylene glycol bath, and finally evacuated down to 0.8 kPa for approximately 2 h. A volume of water corresponding to approximately 40% of the total volume of the cell was added.…”

“…It must be noted that in order to ensure accuracy, a stepwise increase of 0.1 K was adopted in the vicinity of the dissociation point. The point corresponding to the sharp change of the slope on the pressure–temperature data plot was considered as the dissociation point. − …”

Phase Equilibria of Double Semiclathrate Hydrates Formed with Tetraamylammonium Bromide Plus CH4, CO2, or N2

“…Clathrate hydrates are found to be stabilized by van der Waals forces between guest molecules and host water molecules. And they have been recognized as an innovative medium for many positive applications, such as gas storage, , gas separation, , energy storage, − water desalination, separation of close-boiling point compounds − and so forth. However, the high equilibrium pressures required for the hydrate formation are the primary drawback in the application of these hydrate-based technologies.…”

Recent Advances in Experimental Measurements of Mixed-Gas Three-Phase Hydrate Equilibria for Gas Mixture Separation and Energy-Related Applications

“…Similarly, the mixture C 2 H 2 + C 3 H 6 (propene or propylene) is encountered in hydrocarbon cracking streams and during the pyrolysis of polyethylene (a process used for the conversion of a solid waste into valuable chemicals). Hydrate equilibrium data for the binary gas mixture have been reported by Tumba et al and could be used for the design of hydrate-based separation of the mixture.…”