煤田燃空区阻化泡沫扩散封堵特性及高位热置换灭火效应

Coal fire is a main disaster in the coal mining that poses a serious threat to the safety production. Inhibition foam is used as an efficient means of coal fire prevention in combustion cavity of coal field. The extinguishment effect lies on the three-dimensional diffusion and coverage of inhibition foam in the high temperature fractures that blocks the air leakage. The inhibition foam wets the high temperature coal in depth and suppresses the coal recrudescence efficiently. The high temperature heat is displaced from the combustion cavity via the inhibition foam rapidly that creates a permanent low-temperature inerting environment. In this project, the foam flow law in the combustion cavity is explored as a breakthrough point. An experimental platform of foam infusion is proposed to investigate the foam diffusion radius and the limiting accumulation altitude. Meanwhile, the morphologic change of foam is clarified and the blocking characteristics are evaluated in the high temperature fractures. Then the adhesion and wettability as well as the resurgence prevention of inhibition foam are researched systematically, which root in the three levels of packing the high temperature coal surface, wetting coal and changing the coal structure. Ultimately, the upper thermal displacement of inhibition foam is expounded for the large heat combustion cavity. The foam rupture and accumulation law is revealed on a high temperature condition. The upper thermal displacement effect of inhibition foam is evaluated through the synergy to strengthen function. The cooling process of substitution high temperature foam is analyzed along the fractures or boreholes. Based on the above contributions, this study is of great importance to provide the scientific basis and theoretical guidance for preventing the combustion cavity using inhibition foam.

煤火是煤田开采中的主要灾害，阻化泡沫是防治煤火的有效手段，其能否有效治理煤田燃空火区，关键在于阻化泡沫能否在高温裂隙内形成立体扩散堆积，覆盖全部燃空区，稳定封堵裂隙漏风，深度浸润高温煤体，阻化煤复燃，并快速置换出燃空区内的高温热量，使燃空区持久处于低温惰化环境。本项目以研究燃空区内阻化泡沫流动规律为切入点，提出构建煤田火区阻化泡沫灌注实验平台，分析阻化泡沫扩散半径及极限堆积高度，明确高温裂隙内泡沫骨架形态及承压封堵特性，然后从阻化泡沫附着包裹高温煤体表面、浸润煤体、改变煤体内部结构三个层面，微观探究阻化泡沫对高温煤体的附着润湿及防复燃特性，最后从宏观层面阐释阻化泡沫对大热容燃空区的高位热置换效应，揭示阻化泡沫的高温烧变规律，评估阻化泡沫的协同强化热置换效能，分析置换出高温泡沫沿裂隙（钻孔）的散热特性。基于上述研究，为阻化泡沫治理煤田燃空区的合理实施提供重要的科学依据和理论指导。

煤炭自燃严重威胁着矿井安全生产。工程实践表明，煤炭自燃存在火区隐蔽、致灾区大、火源高位及易复燃的特点，造成传统统注浆等防灭火措施在应对煤炭自燃时存在一定不足。本项目提出了采用大流量高倍阻化泡沫防控煤田自燃方法，并以实验为主，结合理论分析和数值模拟，研究了阻化泡沫的空间扩散封堵特性及高位灭火规律。构建了可视化阻化泡沫灌注多孔介质自燃区域平台和封堵性能测定装置，评估了阻化泡沫对煤火多孔裂隙的承压封堵规律，全时段分析了阻化泡沫穿越微孔裂隙的行为特性，得出了阻化泡沫空间扩散函数及最优化灌注工艺参数；研究了不同阻化泡沫对煤体特征温度、氧化放热强度及气体产生量的影响，测定了阻化泡沫对煤的润湿及抗烧特性，开展了不同氧化程度煤自燃倾向性规律研究，并从微观层面揭示了阻化泡沫对煤自燃活性官能团的抑制作用；分析了煤田火风压对煤火高位蔓延的动力作用，阐明了阻化泡沫覆盖煤自燃高位火源时的破裂行为特性，量化分析了阻化泡沫对高温火源的冷却降温效果，对比分析了阻化泡沫灌注对燃空区温度及焓值的影响，评估了大空间燃空区内阻化泡沫的高效热置换效应。相关研究可为阻化泡沫防控煤田燃空区火灾工业实践提供重要的基础理论，为矿井煤自燃的高效防控提供一定的技术支撑。