纳米复合粉体抑制甲烷煤尘共存体系爆炸动力学机理研究

Gas-coal explosion is one of the major accidents in coal mines, which poses a serious threat to the safety production. In this project, a novel potassium oxalate- potassium montmorillonite nano-composite explosion inhibitor with high efficiency of physical and chemical synergistic effect is prepared by using acid modification, ion exchange modification, antisolution-dissolution method and liquid precipitation method. The nano-potassium oxalate particles are loaded on the surface of potassium montmorillonite base material. Experimental studies on pyrolysis behavior, flame propagation behavior and pressure accumulation behavior of methane-coal coexisting explosions intervened by nano-composite inhibitors are conducted. The suppression effect of nano-composite inhibitors on the pyrolysis kinetic parameter and pyrolysis product distribution, the microscopic fine structure and propagation behavior of turbulent combustion flame, and the overpressure evolution characteristic of methane-coal coexisting explosions are discussed. Finally, considering the explosion overpressure evolution characteristic, the thickness of flame preheat zoon and combustion zoon, the combustion reaction intensity, the flame temperature distribution, the dominant heat transfer mode, the flame flow filed distribution, and the pyrolysis kinetic and chemical reaction kinetic characteristics, the physical model of methane-coal coexisting explosion suppression mechanism is developed to further reveal the dynamic suppression mechanisms of nano-composite explosion inhibitor on methane-coal coexisting explosions. The present study will provide theoretical and technical support for prevention and mitigation of gas coal explosions in coal mines.

瓦斯煤尘爆炸是煤矿的主要事故之一，严重威胁煤矿的安全生产。本项目采用酸改性、离子交换改性、反溶剂-溶析法和液相沉淀法制备以钾蒙脱石为基体，表面负载纳米草酸钾粒子，具有物理与化学高效协同抑爆效应的新型草酸钾-钾蒙脱石纳米复合抑爆粉体。通过纳米复合抑爆粉体干预下甲烷煤尘共存体系热解、火焰传播和压力积聚行为的实验研究，分析纳米复合抑爆粉体对甲烷煤尘共存体系热解动力学参数及产物分布、湍流燃烧火焰微观精细结构及火焰阵面传播行为、以及爆炸超压演化特性的抑制规律；建立纳米复合抑爆粉体作用下考虑爆炸超压动态演化特征、火焰预热区厚度、燃烧区厚度、燃烧反应强度、温度分布、主导传热模式、湍流流场分布、热解动力学及化学反应动力学特征的甲烷煤尘共存体系爆炸超压及湍流火焰传播抑制机理物理模型，进而揭示纳米复合抑爆粉体对甲烷煤尘共存体系爆炸的动力学抑制机理。研究成果可为瓦斯煤尘爆炸事故的有效防控提供理论基础和技术支撑。

瓦斯煤尘爆炸事故严重威胁煤矿的安全生产。本项目采用酸改性、离子交换改性、反溶剂-溶析法和液相沉淀法制备了以钾蒙脱石为基体，表面及层间负载草酸钾，具有物理与化学高效协同抑爆效应的草酸钾-蒙脱石（OA-MMT）纳米复合抑爆粉体。应用高温管式热解炉、气相色谱仪、同步热分析仪和红外光谱仪探明了OA-MMT复合抑爆粉体对甲烷煤尘热解氧化特性、热解气体产物分布及热解固体产物官能团分布的影响。应用改进的气粉两相爆炸火焰传播实验系统及20 L爆炸实验装置，系统分析了OA-MMT复合抑爆粉体对甲烷煤尘共存体系爆炸湍流火焰阵面传播行为及爆炸超压演化特性的抑制规律。考虑甲烷煤尘共存体系爆炸从热解到燃烧的全过程，建立了描述OA-MMT复合抑爆粉体对甲烷煤尘共存体系爆炸抑制机理物理模型，进而揭示了纳米复合抑爆粉体作用下考虑爆炸超压动态演化特征、火焰动力学传播特征及热解动力学特征的甲烷煤尘爆炸抑爆机理。结果表明，OA-MMT复合抑爆粉体热解气相产物及其燃烧释热引发固定碳更为充分的燃烧而引起的压力增大作用是甲烷煤尘共存体系爆炸最大压力上升现象的主导机制。OA-MMT复合抑爆粉体对甲烷煤尘爆炸过程中的热解反应、及可燃挥发分气体的气相燃烧反应的抑制效果十分显著，显著降低了火焰亮度与火焰传播速度vi、延长了达到瞬时速度峰值所需时间tv、提高了火焰平均速度抑制率φ、降低了爆炸压力上升速率(dP/dt)m、推迟了压力上升特征时间t0及t1、延长了压力缓慢上升阶段持续时间及延长了达到压力峰值所需时间ts。且在80%草酸钾包覆比例下，OA-MMT复合抑爆粉体对甲烷煤尘共存体系爆炸特性的干预与抑制效果最佳；随着OA-MMT复合抑爆粉体添加量的增大，其对甲烷煤尘共存体系爆炸产生的物理及化学协同抑制作用显著增强，能够有效抑制甲烷煤尘爆炸的发展。研究成果可为瓦斯煤尘爆炸事故的有效防控提供理论基础和技术支撑。