Experiment on coal-bed methane hydrates formation in the ultrasonic field

摘要

China is rich in coal bed methane (CBM) resources, according to estimates, coal bed methane resources of about 30 × 1012 ～ 35 × 1012m3 above 2000 m depth. A large number of coal bed methane directly is pumped into the atmospheric environment, not only pollutes the environment, but also causes great waste of energy. In view of this, the method of combined technology of ultrasonic and hydrate is ap plied to develop and utilize coal-bed methane in this paper. The experiments were performed in a high pressure experimental system with ultrasonic (20 kHz, 0 ～ 150W). The effect of ultrasonic on the forma tion of coal-bed methane hydrates was investigated, including the characteristic curve of formation, induc tion time. The experimental results indicate that the characteristic curves of temperature, pressure and flow-time are different with those of the static. And the induction time with ultrasonic was about 1/6 of that of the static and only about 1/10 if rehydration after decomposition. According to the mechanism of ultra sonic and nucleation theory, the increase of the nucleation rate should appeal to the increases of the mass transfer coefficient, the concentration of nucleation-active particles, supersaturation and the decrease of surface energy with ultrasonic.