浸水过程对长焰煤自燃特性的影响

为揭示长期浸水长焰煤的自燃特性及影响机制,实验研究了长焰煤原始煤样和长期浸水风干煤样的低温氧化特性,分析了长期浸水对煤微观结构、氧化升温过程及活化能等方面的影响规律。研究结果表明:长期被水浸泡煤样的表面孔隙结构更发达,平均孔径、介孔孔容和微孔孔容都有不同程度的增大;同时,浸水煤样表面的部分有机物和无机物会溶解在水中,煤中自由基浓度增加,基团分布与原煤相比存在明显变化;与原煤样相比,经过90,180 d浸水过程后的煤体,低温氧化过程的气体产生量和产生速率更高,交叉点温度由原煤的160.9℃降低至157,151.5℃,活化能分别降低了3.84,4.18 k J/mol,表现出更高的自燃倾向性。研究结果可为西部浅埋藏近距离煤层群开采上覆采空区长期浸水煤的自燃防治提供借鉴。

Effect of soaking process on spontaneous combustion characteristics of long-flame coal

In order to find out the spontaneous combustion characteristics and affecting mechanism of long term soaked long-flame coal,this paper analyzed the low temperature oxidation characteristics of long-flame raw coal and soaked and air-dried coal.The effect on the microcosmic structure,self-heating process,activation energy and so on was also analyzed.The results show that the coal soaked in water for a long time has a more developed surface pore structure,the average pore size,mesoporous volume and micro-pore volume increase at different degrees.Simultaneously,some of organic and inorganic substances on the coal surface will be dissolved in water,the concentration of free radical in coal increased and the group distribution has obvious change compared with the raw coal.After 90 and 180 days of water immersion,the amount and rate of gas production during the low temperature oxidation process are higher,the cross point temperature is reduced from 160.9 ℃ to 157 ℃ and 151.5 ℃,the activation energies decreased by 3.84 kJ/mol and 4.18 kJ/mol,respectively.And the soaked and air-dried coals have higher spontaneous combustion tendency.This study provides a scientific guidance for prevention and control of spontaneous combustion of the soaked and air-dried coal in shallow buried close distance coal seam group mining overlying coal goaf in western privinces.