Effect of Hydrate Shell Formation on the Stability of Dry Water

Abstract

This study investigates the effect of gas hydrate formation on the stability of dry water (DW) particles when they are exposed to high pressure methane at low temperatures. The DW particles are prepared by mixing water with hydrophobic silica nanoparticles at high speed to form a water-in-air inverse foam. A high pressure autoclave was used to determine the hydrate equilibrium conditions and formation characteristics including hydrate onset time, subcooling temperature, and initial growth rate. In comparison to bulk water, the equilibrium conditions for methane hydrate are shifted to higher temperatures and low pressures, suggesting that the silica nanoparticles promote the hydrate equilibrium conditions. The surface-to-volume ratio between the gas and the water encapsulated by the silica nanoparticles is increased in comparison to bulk water which enhances the kinetics of methane hydrate formation without the need for vigorous mixing. However, after multiple cycles of hydrate formation and dissociation, ...