Hydrate Formation by Water Spraying in a Methane + Ethane + Propane Gas Mixture: An Attempt at Promoting Hydrate Formation Utilizing Large-Molecule Guest Substances for Structure-H Hydrates

Abstract

An experimental study of hydrate formation has been performed, using a simulated natural gasa mixture of methane, ethane, and propane in a 90:7:3 molar ratioand a liquid large-molecule guest substance (LMGS), which provides guest molecules to fit into the 51268 cages of a structure-H hydrate. Except for the use of the gas mixture, the hydrate-forming procedure used in this study was the same as that tested in our previous studies [Ohmura et al., Energy Fuels 2002, 16, 1141−1147; Tsuji et al., Energy Fuels 2004, 18, 418−424], i.e., spraying liquid water downward through a gas phase onto a liquid−LMGS layer lying on a pool of water under a prescribed temperature−pressure condition (275 K, 2.9 MPa) in a chamber into which the gas mixture was being supplied to compensate for its loss due to hydrate formation. We selected three LMGSs for comparison: tert-butyl methyl ether (TBME), which was found to give the highest rate of hydrate formation when pure methane is used as the guest gas [Tsuji et al., Energy Fue...