基于煤火发展演化的松散煤体自燃温度纵深蔓延特征

Temperature field migration characteristics of loose coal based on experimental scale

针对现有对松散煤体自然发火温度场运移特点试验装置的不足,根据实际松散煤体燃烧特点,自主设计研发了煤火发展演化模拟实验系统。选取陕西省咸阳孟村煤矿煤样为研究对象,利用该装置模拟松散煤体燃烧过程,分析松散煤体燃烧过程中高温区域的分布及纵深移动规律,再现松散煤体从着火至燃烧最后燃尽过程中高温区域的蔓延过程,剖析温度区域迁移机制,分析高温区域关键点氧气体积分数变化规律。结果表明,在松散煤体燃烧过程中,煤样体系温度变化尺度随着时间的增加先上升后下降,试验运行600 h后,整体燃烧室降至环境温度;试验过程中松散煤体高温区域集中于煤火发展演化模拟实验装置中部以及西侧部分;高温区域纵深移动方向呈现非线性规律;高温区域在纵深蔓延过程中关键点温度呈依次降低的趋势,且下降到极限氧体积分数(1%~3%)的时间与其达到燃点温度时间相近;温度下降阶段,高温区域关键点在同层测点中下降趋势最慢;随着纵向深度增加,高温区域关键点燃点温度与峰值温度对应的时间差呈指数形式增长,关键点从燃点到达峰值的温度增长速率基本呈线性下降;高温区域关键点氧气体积分数快速下降阶段所经历的时间随着纵深的增加逐渐增大。研究成果可为煤堆、遗煤、煤炭储存状态下等的松散煤体自然发火的防治提供借鉴。

In view of the shortage of existing test equipment for the migration characteristics of natural combustion temperature field of loose coal,according to the actual combustion characteristics of loose coal,the simulation experimental system of coal fire development and evolution was designed and developed independently.The coal samples of Mengcun Coal Mine in Xianyang,Shaanxi Province were selected as the research object,and the combustion process of loose coal was simulated by the device developed,and the distribution and depth movement of high temperature area during the combustion of loose coal were analyzed.The results show that in the process of loose coal combustion,the temperature scale of coal sample system increases first and then decreases with the increase of time,and the whole combustion chamber decreases to ambient temperature after 600 hours of test operation.The deep movement direction of the high temperature area shows a non-linear law.During the test,the high temperature area of loose coal was concentrated in the middle and west parts of the coal fire development and evolution simulation experiment device,and the time of falling to the limit oxygen concentration(1%-3%)was similar to the ignition temperature.In the temperature drop stage,the key points of the high temperature region were the slowest among the measurement points of the same layer.During the test,the high temperature area of loose coal was concentrated in the middle and west parts of the coal fire development and evolution simulation experiment device.The temperature of the key point decreases in turn in the process of deep spreading.With the increase of depth,the time difference between the key ignition point temperature and the peak temperature increases exponentially in the high temperature region,and the growth rate decreases linearly after the key point temperature reaches the ignition temperature.The time range of the rapid decline of oxygen concentration at key points in high temperature region increases with the increase of depth.The research results can provide reference for the prevention and control of spontaneous combustion of loose coal such as coal piles,residual coal and coal storage.