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

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CO_2或N_2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(CO_2,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。

In the underground fire zone,high temperature coexists with inert gases after inert injection,and the O2con-centration remains a lower level. Spontaneous combustion characteristics of coal are partially changed by the joint effectof temperature and inert gases such as CO2 or N2. Taking the Qingdong bituminous as an example,the coal sample waspretreated for 24 h at an inert or low-oxygen environment（CO2,N2,10% O2） under 200 ℃. The physicochemicalproperties of coal were analyzed according to the FTIR,pore analysis and TG test. Oxidation products were comparedvia the temperature-programmed experiments. The results show that after treatment the coal is easier to self-ignition. Itsactivation energy decreases,but the critical temperature increases. Besides,the proportion of mesopores and macroporesincrease,and the permeability and porosity of coal also rose significantly. In addition,the C=O and C—O functionalgroups increase,while the —OH and heteroatomic groups in coal decrease. Further,various types of connected cracksand porosities are generated,which enhance the gas flow in coal.