Influence of water saturation and particle size on methane hydrate formation and dissociation in a fixed bed of silica sand

In this work, the effects of water saturation and particle size on methane hydrate formation and dissociation in a fixed bed of silica sand were investigated. The experiments were carried out at 277.15 K with the initial pressure fixed at 8 MPa. Three water saturations (50%, 70%, and 90%) and two particle sizes (0.18-0.25 mm and 0.3-0.9 mm) of silica sand were used. The results indicated that water conversion to methane hydrates increased with the decrease of water saturation. 70% was found to be an optimum water saturation due to the largest hydrate amount and the highest gas uptake obtained using the small particle size of silica sand (0.18-0.25 mm). In addition, hydrate formation rate and gas uptake obtained using small particle size of silica sand were larger, and gas recovery and hydrate dissociation rate were higher in the dissociation experiments using the small particle size of silica sand. Therefore, the medium water saturation (70%) and small particle size (0.18-0.25 mm) are favorable for methane hydrate formation and dissociation in the fixed bed of silica sand. (C) 2019 The Authors. Published by Elsevier Ltd.