煤田火区自燃气体排放及运移特性研究

Coal field fire is long in combustion time, wide in combustion area and serious in hazard, and has become one of the natural disaster problems to be solved. Coal field fire zone of our country mainly locates in the northwest region,such as Inner Mongolia Autonomous Region and the Xinjiang Uygur Autonomous Region, which are the main producing area of coal in China for the future. The content of this item include: (1) analyze the release quantity and dissipative of gases produced in the whole spontaneous combustion period of coal field fire, set up the quantitative model on spontaneous combustion gas emmision; (2) systemically study the heat and mass diffusion law of high temperature gas under the action of surface wind, buoyancy and underground coalmine ventilation, acquire the coal fire temperature distribution, seepage velocity distribution and thermal action depth; (3) based on the gas emission law and heat and mass diffusion law, study coal field fire stage evolution types, characters and critical conditions, then develop the application technology. The fruits will provide supports for predicting coal field fire green gas released quantity, coal field fire scope and spread law in theory and technology. It is important to enhance the pertinence and validity of coal field fire and mine fire extinguishment, and is also significant to realize the energy conservation and emission reduction targets in the 12th five years program in polity.

煤田火区燃烧历史长、燃烧面积大、危害性大，已成为当前亟待解决的自然灾害之一。我国煤田火区主要集中在新疆、内蒙古、宁夏等西北地区，而内蒙古、新疆地区是我国今后煤炭开采重点。项目以煤田火区为研究对象，定量分析煤自燃发展全过程气体生成释放和耗散规律，建立气体排放量的计算模型；综合研究在地表自然风、浮力作用与井下通风等强迫对流作用下自燃高温气体煤岩介质中的热、质扩散规律，获得煤田火区气体在煤岩中的温度分布、渗透速度分布以及热作用深度等；利用自燃气体排放模型和吸附-扩散模型为基础，获取煤田火区发展演化类型和临界条件以及现场实践应用技术。研究成果对于为较准确的预测煤田火区温室气体排放量、预测煤田火区范围和发展趋势提供理论和技术支持，能有效提高煤田火区和井下火区灭火工程的针对性和有效性，提高工程效率、降低灭火工程成本和工期，对我国 "十二五"节能减排目标的实现也有重要的政治意义。

项目研究煤田火区贫氧缓慢燃烧生成气体较为准确的量化模型及火煤田火区自燃生成气体在自然环境中的耗散、热扩散和火区蔓延规律。研制了可实现室温-800℃的煤自燃全阶段模拟系统，并通过我国10种典型煤种的自燃实验和热分析实验，获得了煤自燃过程特征温度变化规律以及地表扩散漏风和存在采空漏风两种模式下的典型煤种自燃气体生成特征。结合10个煤种的红外光谱实验，得出了典型煤种自燃过程中主要温室气体产物释放因子和释放量计算方法。通过进行小尺寸-中尺寸和火区现场尺度下的煤自燃排放气体的对比实验，分析了煤自燃气体排放的小尺寸-中尺寸-火区的温室气体排放的差异性，构建了相应的尺度效应修正模型。通过页岩、砂岩、泥岩、砂土四种煤层上覆岩石介质对CO2-CH4-N2的多元吸附实验，得出了煤自燃释放的主要温室气体气体经过上覆岩层介质的耗散特征，构建了煤自燃释放温室气体不完全排放效应的计算方法。通过实验得出了火区高温气体在煤岩介质内传播过程中的传热、渗流、扩散特征，并建立了相应的数学模型。分析了自燃火区高温气体扩散的热动力系统特征，并应用数值模拟技术得出了在不同地表风速、地形、煤层赋存条件、采空区漏风等多因素影响的高温火源沿煤层走向和倾向的蔓延规律及热作用深度。项目研究成果对于提高煤田火区环境效应评估的准确性以及煤田自燃火区灭火工程的可靠性和安全性具有重要的理论和实践意义。