Enhanced methane hydrate formation using promoters for natural gas storage and transportation application

Abstract

Solidified natural gas (SNG) is an alternative technology for natural gas storage and transportation in the clathrate hydrate formed. It has higher volumetric energy storage with the ease to handle not to mention its safety. Effects of different hydrate promoters, including methyl ester sulfonate (MES), tetrahydrofuran (THF), hollow silica (HS), and sodium dodecyl sulfate (SDS), on the methane hydrate formation was investigated. All experiments were performed in an unstirred tank reactor at desired experimental conditions. The results indicated that all promoters significant enhanced the hydrate formation both kinetics and methane uptake compared with pure water. The increase in the MES concentration decreased the induction time and increased the hydrate formation rate, which was the result from the decrease in the surface tension between gas and liquid phase. The methane uptake increased with the increase in the MES concentration. The presence of THF shifted the hydrate phase equilibrium curve to the higher temperature and lower pressure. The results showed that the increase in the experimental temperature increased the methane uptake due to the effective heat distribution to the surrounding, while the hydrate formation kinetics decreased due to the decrease in the driving force. The decrease in the pressure did not affect the methane uptake but the hydrate formation kinetics decreased. There was synergism between THF with MES in the hydrate formation kinetics at the higher temperatures. Moreover, the presence of HS improved the surface contact area to enhance the hydrate formation at moderate conditions. The presence of SDS facilitated the hydrate formation, including induction time and hydrate formation rates, at moderate conditions.