Experimental study on surface structure evolution and spontaneous combustion indexes of soaked coal
In order to improve the reliable and accurate of self-ignition warning for soaked coal,this paper studied the structural changes and oxidation laws of coal with different moisture contents and raw coal by using scanning electron microscopy experiments and programmed temperature oxidation experiments.Firstly,the surface structural changes of the soaked coal were compared and analyzed.Then,coal samples with moisture contents of 4％,11％,18％,25％,and 32％were prepared by soaking method.Finally,the relationship between the amount of gas produced in each coal sample and temperature using a programmed heating experiment was analyzed.The results showed that the critical temperature for the oxidation of the soaked coal samples to produce CO and C2H4 increased from 73 ℃ and 180 ℃ to 62 ℃ and 161 ℃ respectively.The amount of gas produced during the heating process of each coal sample increased with the increase of temperature.The coal sample with a moisture content of 18％produced the highest concentration of CO,CO2,C2 H4 and C2H6.On the basis that CO and C2 H4 could be single indicator gases,CO/CO2(γ)and C2 H4/C2 H6(ε)were introduced as the predictive indicators for coal oxygen absorption and thermal storage stage and self-thermal oxidation stage respectively.When γ≤ 0.019,the coal sample,with a temperature less than 136 ℃,was in the stage of oxygen absorption and heat storage temperature.When 0.752≤ε≤0.836,the temperature of coal sample was 136～226 ℃,and it was in the stage of the self-thermal oxidation.When γ≥ 0.908,the coal sample,with an oxidation temperature of greater than 226 ℃,could be considered to be in the accelerated oxidation stage.Finally,based on the three single indicator gases of CO,C2H,,C2 H6 and γ,ε,a graded warning and prevention indexes system for the residual coal in goaf under waterlogging conditions was established.
soaked coalscanning electron microscopetemperature programmed experimentsurface structurespontaneous combustionindicator gas
万方数据
维普
