Inlet configuration of a recovery system for methane hydrate using gas lift

In recent years, abundant deposits of methane hydrate, a principal ingredient of natural gas, have been reported under the ocean floor around Japan and all over the world. Methods such as heat stimulation and decompression have been proposed for recovery of this methane hydrate, but the gas-lift method considered here has the possibility of more economical efficiency than the other recovery systems. Although the design of the bottom of the inlet pipe is important to efficiently recover hydrate from the seabed, the flow around the inlet pipe and optimal shape have not been examined. The present paper studied the flow around the inlet of recovery pipe and the indrawn particle behavior by experiments and numerical simulations. An umbrella-shaped inlet pipe was proposed in order to expand recovery area and enhance recovery efficiency compared with a normal cylindershaped pipe. Turbulent flow simulations were conducted for the umbrella-shaped inlet pipe with the k-e model. The simulation results were compared with those of experiments with a recovery pipe length of 1.6 m, in which the flow near the inlet was measured by (Particle Image Velocimetry (PIV) system. The experimental results agreed well with the simulation results, and the efficiency of the umbrella-shaped inlet pipe was clarified.