Investigation of methane hydrate formation and dissociation kinetics with the presence of promoters for gas storage application

Abstract

Gas hydrate is of interest for the process to store and transport gas. However, the slow kinetics and the storage capacity remained the obstruction. In this study, the hydrate promoters, including activated carbon, tetrahydrofuran (THF) and sodium dodecyl sulfate (SDS), were investigated for methane hydrate formation and dissociation kinetics. The experiments were conducted in a quiescent condition in a batch reactor at the desired experimental conditions. The results showed that all promoters significantly enhanced the kinetics of methane hydrate formation compared to pure water. In other words, the addition of porous media could increase the contact area between gas and liquid, SDS reduced the interfacial tension of the liquid phase, while THF shifted the methane hydrate phase equilibrium to higher temperature and lower pressure. A small particle size of activated carbon showed the fastest induction time; however, the highest gas consumption was observed with a large particle size. In contrast, a small particle size showed the fastest hydrate dissociation. Moreover, the surface treatmer.t of activated carbon resulted in the increase in the gas consumption. In the system of THF, at the same concentration, increasing the experimental temperature led to the decrease in the kinetics of hydrate formation but the increase in the gas consumption; however, it was not stable at high temperature. The higher THF concentration exhibited a faster induction time than that of the lower concentration. Mixed THF-SDS showed the synergetic effects on the methane hydrate formation kinetics.