不同通风条件下的煤颗粒堆积床阴燃传播特性

Smouldering Propagation Characteristics of Coal Piles Under Different Ventilation Conditions

地下煤火持续燃烧是煤火阴燃蔓延的结果,设计搭建实验室尺度下的煤火阴燃实验模拟装置,研究了煤炭在强制点火后的阴燃传播过程.通过改变每组实验装置的边界通风条件,了解影响阴燃发生和发展的相关因素.结果表明:阴燃过程中煤-氧反应强度主要取决于局部氧浓度,供氧和散热主导下的典型阴燃峰值温度在500~650℃之间;热传导和氧化反应维持着着干燥锋的水平传播;侧边通风加快了边界处煤样的氧化反应进程,峰值温度上升至原来的1~1.2倍,对远离边界的内部煤样升温过程影响逐渐减小直至消失;顶部盖板将浅层煤样中干燥锋传播所需的6.8 h缩短近一半,使其能够提早进入快速氧化阶段,同时限制氧气获取,氧化反应强度降低.

The continuous burning of underground coal fire is the result of smouldering propagation.A laboratory scale smouldering experiment simulation device was designed and built to study the smouldering spread process of coal after forced ignition.By changing the boundary ventilation conditions of each experimental unit,the related factors affecting the occurrence and development of smouldering were understood.The results show that the coaloxygen reaction intensity mainly depends on the local oxygen concentration,and that the typical smouldering peak temperature is between 500℃and 650℃under the dominance of oxygen supply and heat dissipation.The heat conduction and oxidation reaction help maintain the horizontal propagation of the drying front.The side ventilation accelerates the oxidation reaction process of coal samples at the boundary,the peak temperature rises to 1—1.2 times of the original value,and the influence on the heating process of the coal samples in the interior far away from the boundary gradually decreases and finally disappears.Due to the cover plate,the time required for the propagation of the drying front in shallow coal samples is reduced almost by half,which is originally 6.8 h,enabling the samples to enter the rapid oxidation stage earlier.Meanwhile,the oxygen acquisition is restricted and the oxidation reaction intensity is reduced.