风化水浸煤微观特性及氧化性能实验研究
Experimental study on microscopic properties and oxidation performance of weathered water-leached coal
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摘要:
为揭示煤体水浸后在自然风干条件下的微观孔隙结构及氧化动力学参数的变化规律,本文选取永陇矿区麟游区1#堪察区崔木矿侏罗纪延安组3#煤层水浸煤样作为研究对象,实验测定了煤样水浸风化前后煤样的微观孔隙结构变化,以及煤样在高温氧化阶段及低温氧化阶段标志性气体析出浓度变化,并诠释了水浸煤自然风化过程及遗煤氧化影响因子。研究结果表明:大孔占煤样总孔隙的百分比由原始煤样中的36.71%增加至水浸60 d后煤样中的46.78%,孔径介于10~1 000 nm的中孔占煤样总孔隙的百分比变化趋势不明显,微孔占煤样总孔隙的百分比由原始煤样中的31.20%降低至23.18%,其总孔隙面积并未呈现出明显增加,但煤样的平均孔径、渗透率、孔隙率发生了明显变化;外在水分对遗煤内部羰基、羧基等含氧官能团含量的提高起到促进作用,而遗煤内部进一步增强了煤的自燃倾向性,含氧官能团的增加也进一步使得遗煤在自然发火进程中生成的CO气体产物多于原始煤样;原始煤样初次及二次氧化升温、降温过程中低温氧化阶段与高温氧化阶段的表观活化能平均值为44.06,长期水浸风干煤样初次及二次氧化升温、降温过程中低温氧化阶段与高温氧化阶段的表观活化能平均值为33.71,其表观活化能平均值下降了23.49%。
Abstract:In order to reveal the change law of microscopic pore structure and oxidation kinetic parameters of coal under natural air-drying conditions after water immersion, the water-soaked coal sample of the Jurassic Yan’an Formation 3# coal seam of the Cuimu Mine in the Linyou District of Yonglong mining area is selected as the experimental research object in this paper.The change of the concentration of the characteristic gas in the high temperature stage and the low temperature oxidation stage of the coal sample, and explains the natural weathering process of the water-leached coal and the influencing factors of the residual coal oxidation.The research results show that the percentage of large pores in the total coal sample increased from 36.71% in the original coal sample to 46.78% in the coal sample after water immersion for 60 days, and the medium pores with inner diameters ranging from 10 to 1 000 nm accounted for the percentage of the total coal sample pores, the change trend is not obvious.The percentage of micro pores in the total pores of the coal sample decreased from 31.20% in the original coal sample to 23.18%, and the total pore area did not show a significant increase, but the average pore size, permeability, porosity of the coal sample significant changes have taken place; external moisture promotes the increase in the content of oxygen-containing functional groups such as carbonyl and carboxyl groups in the left coal, and the interior of the left coal further enhances the spontaneous combustion tendency of the coal, and the increase of oxygen-containing functional groups further makes the left coal.In the process of spontaneous combustion, more CO gas products are generated than the original coal samples; the average apparent activation energy of the low temperature stage and the high temperature stage in the primary and secondary oxidation heating and cooling processes of the original coal samples is 44.06, the long-term water immersion air-dried coal samples, and the average value of the apparent activation energy in the low temperature stage and the high temperature stage in the heating and cooling process of the primary and secondary oxidation is 33.71, and the average value of the apparent activation energy decreased by 23.49%.