The 4th International Symposium on Mine Safety Science and Engineering (ISMSSE2018)

216 / 2018-07-06 15:07:32

Effects of different particle size and adsorption pressure on gas diffusion in coal

coal; gas diffusion; different particle size; adsorption pressure

Gas of Coal Mine & Coal and Gas Outburst > Gas of Coal mine

In coal gas mainly exists in free and adsorption state. When coal containing gas is disturbed, gas desorption and diffusion will occur. The gas desorption and diffusion will play an important role for gas production and gas disaster mechanism and prevention. Thus, in this work the mathematic model of gas diffusion and experiment of gas diffusion of different particle size and adsorption pressure is done. And gas diffusion coefficients is calculated by the developed model. The influence of different particle size and adsorption pressure on gas desorption rate, gas accumulated desorption amount and gas diffusion coefficients is discussed and mechanism of different particle size and adsorption pressure on gas diffusion is analyzed. The research results indicate that gas initial desorption rate decreases and gas desorption equilibrium time increases with increasing coal particle size under the same temperature and closed adsorption pressure. Higher the gas initial desorption rate and gas desorption rate change in the same time period, higher the adsorption equilibrium pressure under the same temperature for the same coal particle size. Under the same temperature and coal particle size higher gas adsorption pressure, more gas accumulated desorption amount and gas desorption amount change for the same time period in initial gas desorption process. But coal particle size has little influence on gas accumulated desorption amount. Adsorption pressure has no obvious effect on gas diffusion coefficient calculated by the developed model. But for the same coal and adsorption pressure the smaller coal particle size, the smaller gas diffusion coefficient. And gas diffusion coefficient decreases with time