(356a) SNG Technology Via Clathrate Hydrates for Large Scale Storage of Natural Gas
Increasing global demand and widespread applications of natural gas (NG) necessitate the development of more effective and efficient methods for NG storage and transportation. Conventional methods of NG storage are either energy intensive - LNG (Liquefied Natural Gas) or pose high safety risk as in CNG (Compressed Natural Gas). SNG (Solidified natural gas) via clathrate hydrates is advantageous due to its characteristic advantages that include high volumetric capacity, non-explosive nature, environmentally benign and being relatively less energy intensive compared to conventional methods of NG storage. However, a significant challenge that impedes the commercial development of SNG technology is the slow rate of hydrate formation. For the first time, we report an increased rate of mixed methane hydrate formation in a simple unstirred tank reactor configuration (UTR) at moderate temperature and pressure conditions employing tetrahydrofuran (THF) as a promoter. THF was observed to function as a thermodynamic as well as an excellent kinetic promoter for hydrate formation at 283.2 K and moderate pressures (3.0-7.2 MPa). Substantial methane gas uptake of 3.52 (±0.13) kmol/m3 of water is possible even at reduced experimental pressure of 3.0 MPa and 283.2 K in 2 h employing the unstirred reactor configuration. At higher temperature of 293.2 K, similar methane gas uptake and formation kinetics (as that observed at 283.2 K) is possible with the addition of just 100 ppm sodium dodecyl sulphate (SDS) surfactant due to the synergism between THF and SDS. Further, we demonstrate multi-scale experimental validation of our method to a volumetric sample scale-up factor of 120 and internal reactor diameter scale-up factor of 10. It is noted that substantial decrease in the severity of the storage conditions can be achieved by the use of THF as a promoter. SNG technology has a potential for a large scale commercial deployment.