密闭火区内惰性环境下烟煤自燃特性变化
Variation in spontaneous combustion properties of bituminous under inert environment of underground fire zone
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摘要: 在注惰后的井下密闭火区中,氧浓度较低,高温与惰性气体共存,高温与CO2或N2等惰性气体的共同作用会在一定程度上影响煤的自燃特性。以安徽淮北青东8号煤为例,在200℃下的惰性或低氧环境(CO2,N2,10%O2)内对煤样预处理12 h。通过红外光谱、孔隙分析、热重测试研究煤样处理后的物理化学变化,并通过程序升温氧化实验对比煤的氧化产物浓度。结果表明,处理后煤样的活化能降低,临界温度降低,自燃特性增强,中孔及大孔的比例增加,渗透率和孔隙率明显增高;煤中C—O,C=O等活性基团增多,而—OH和杂原子官能团含量减少。煤表面形成各类裂隙孔隙相互沟通,增强了气体在煤中的流动性。Abstract: In the underground fire zone,high temperature coexists with inert gases after inert injection,and the O2 con- centration remains a lower level. Spontaneous combustion characteristics of coal are partially changed by the joint effect of temperature and inert gases such as CO2 or N2 . Taking the Qingdong bituminous as an example,the coal sample was pretreated for 24 h at an inert or low-oxygen environment ( CO2 ,N2 ,10% O2 ) under 200 ℃ . The physicochemical properties of coal were analyzed according to the FTIR,pore analysis and TG test. Oxidation products were compared via the temperature-programmed experiments. The results show that after treatment the coal is easier to self-ignition. Its activation energy decreases,but the critical temperature increases. Besides,the proportion of mesopores and macropores increase,and the permeability and porosity of coal also rose significantly. In addition,the C O and C—O functional groups increase,while the —OH and heteroatomic groups in coal decrease. Further,various types of connected cracks and porosities are generated,which enhance the gas flow in coal.