Li Xiaosen

Molecular Dynamics Simulation of Methane Hydrate Dissociation Process in the Presence of Thermodynamic Inhibitor

The dissociation of methane hydrate in the presence of ethylene glycol (11.45 mol.L-1) at 277.0 K was studied using canonical ensemble (NVT) molecular dynamics simulations. Results show that hydrate dissociation starts from the surface layer of the solid hydrate and then gradually expands to the internal layer. Thus, the solid structure gradually shrinks until it disappears. A distortion of the hydrate lattice structure occurs first and then the hydrate evolves from a fractured frame to a fractional fragment. Finally, water molecules in the hydrate construction exist in the liquid state. The inner dissociating layer is, additionally, coated by a liquid film formed from outer dissociated water molecules outside. This film inhibits the mass transfer performance of the inner molecules during the hydrate dissociation process.

Separation and Purification of Methane from coal-Bed Methane via the Hydrate Technology

The separation of methane from coal-bed methane (CBM) via hydrate process using tetrahydrofuran (THF) + sodium dodecyl sulfate (SDS) as additives was investigated in this work. The effect of additives, the concentration of the additives and hydrate memory effect on the hydrate-based separation process were examined at various concentrations of THF + SDS solutions. The results indicate that THF + SDS solutions decrease the formation pressure of methane remarkably and show that the methane concentration in CBM can be enhanced effectively with the system of THF (1.0 mol%) + SDS (500 ppm) in the moderate condition. The concentration of CH4 can be increased by about 20% for the two feed gases (20% and 50% CH4/N2). It indicates the CBM with low methane can be improved to the one which can be used directly by several steps of the hydrate-based separation technology.