Aiming at the limitation of the traditional method for determination of protection region, combined with the actual situation of a mine, a new method for determination of protection region was put forward （including ...Aiming at the limitation of the traditional method for determination of protection region, combined with the actual situation of a mine, a new method for determination of protection region was put forward （including the protection of working face layout and development direction）, that is, gas flow observation analysis on the spot and gas content contrast method. The protection region was determined by gas flow observation analysis, gas content contrast, and computer numerical simulation combined with engineering practice. In the process of gas content test, the fixed sampling method ＂big hole drill reaming, small orifice drill rod connected with core tube＂ was employed. The results show that the determined protection region is in accordance with the actual site situation. The fixed sampling method ensures the accuracy of gas measurement of gas content.展开更多
The self-preservation of methane hydrate is a key process in its engineering applications because the hydrate can survive for a significant period under atmospheric pressure and moderate temperature. Some experiments ...The self-preservation of methane hydrate is a key process in its engineering applications because the hydrate can survive for a significant period under atmospheric pressure and moderate temperature. Some experiments have predicted that the shielding ice formed on the hydrate surface after initial dissociation of the hydrate plays an important role in the self-preservation effect. We propose ice-shielding models of gas hydrates to investigate the dissociation rates quantitatively, including the self-preservation process, at temperatures below the ice-melting point and at atmospheric pressure. Three general models are constructed for two temperature ranges The rate-determining process for the lower temperature range is hydrate dissociation, and those for the higher range are gas diffusion through ice or hydrate layers, which depend on the thickness of the shielding-ice layer. Our models suggest that the extent of self-preservation depends on temperature, original hydrate size, and guest substances, which can explain the experimental results.展开更多
文摘Aiming at the limitation of the traditional method for determination of protection region, combined with the actual situation of a mine, a new method for determination of protection region was put forward （including the protection of working face layout and development direction）, that is, gas flow observation analysis on the spot and gas content contrast method. The protection region was determined by gas flow observation analysis, gas content contrast, and computer numerical simulation combined with engineering practice. In the process of gas content test, the fixed sampling method ＂big hole drill reaming, small orifice drill rod connected with core tube＂ was employed. The results show that the determined protection region is in accordance with the actual site situation. The fixed sampling method ensures the accuracy of gas measurement of gas content.
文摘The self-preservation of methane hydrate is a key process in its engineering applications because the hydrate can survive for a significant period under atmospheric pressure and moderate temperature. Some experiments have predicted that the shielding ice formed on the hydrate surface after initial dissociation of the hydrate plays an important role in the self-preservation effect. We propose ice-shielding models of gas hydrates to investigate the dissociation rates quantitatively, including the self-preservation process, at temperatures below the ice-melting point and at atmospheric pressure. Three general models are constructed for two temperature ranges The rate-determining process for the lower temperature range is hydrate dissociation, and those for the higher range are gas diffusion through ice or hydrate layers, which depend on the thickness of the shielding-ice layer. Our models suggest that the extent of self-preservation depends on temperature, original hydrate size, and guest substances, which can explain the experimental results.
