Hydrate phase equilibrium of hydrogen-natural gas blends: Experimental study and thermodynamic modeling

Blending hydrogen (H2) into natural gas pipelines has become an effective way to transport H2 on a large scale. Due to the difference in properties between H2 and natural gas, the natural gas hydrate (NGH) phase equilibrium will be changed after blending H2, which influences the flow assurance in pipelines. In this work, hydrate phase equilibrium for CH4 + H2, CH4 + C2H6 + H2, and CH4 + C2H6 + C3H8 + H2 multicomponent systems had been measured at a temperature range from 274.24 K to 289.59 K by the isochoric pressure-search method. The results show the inhibition effect on CH4 hydrate formation of blending H2 to 20% is a little better than the 5.0 wt.%CH3OH solution. In addition, the Chen–Guo model was adopted to predict hydrogen-natural gas blends (HNGB) hydrates formation conditions, and model results have a good agreement with the experimental data. Average enthalpies of HNGB hydrates dissociation were also calculated utilizing the Clausius-Clapeyron equation, which was in the range of 68.02 kJ/mol and 90.17 kJ/mol. These studies provide basic data for flow assurance when transporting HNGB in pipelines.