Equilibrium conditions for gas hydrates of methane and ethane mixtures in pure water and sodium chloride solution.

Abstract

The equilibrium conditions were experimentally determined for gas hydrate of methane and ethane mixtures in pure water and 3.0 wt% NaCl solution. The present results indicate that the addition of ethane stabilizes gas hydrate and shifts the equilibrium conditions to higher temperature and lower pressure. As ethane concentration increases from 0 vol% to 10 vol%, the equilibrium pressure of gas hydrate decreases non-proportionally with gas composition, which implies a change in the hydrate structure over this range of gas composition. The equilibrium temperature of gas hydrates of methane and ethane mixtures in 3.0 wt% NaCl solution is approximately 1.0 K lower than that in pure water at a constant pressure.