考虑超压作用的催化型复合粉体抑制管内瓦斯爆炸机理

Coal mine methane (CMM) drainage is helpful to the mine safety and the clean energy supply. The drainage gas will be emitted or utilized after transported to ground. However, low concentration (<30%) CMM accounts for about 70 percent of the methane emissions in China. Low concentration gas has the potential risk of explosion during its transportation in gas pipeline. The active explosion suppression system with the powdered suppressants is considered as one of safety protection techniques mounted on the transportation line for the drainage gas. The.improvement of the inhibition effectiveness and the development of the highly efficient suppressants are the prerequisites for the application of active explosion suppression system. Based on the theory foundation that the inhibition mechanism depends on both the physicochemical property and the experimental conditions, and the effectiveness of suppressants on the inhibition mechanism, a novel catalytic compound powder is proposed for gas explosion suppression in gas pipeline. The scientific problem to be solved is the effect of the pressure action on the understanding of the inhibition mechanism of gas explosions. Overpressure is not only the response to the gas explosion suppression by the powder, but exerts the action on the suppression effectiveness of the powder. Firstly, the influence of the simulated overpressure on the thermal decomposition, the heat extraction, the spectral characteristic of the decomposed gaseous products will be investigated for the catalytic compound powder. Meanwhile, the catalytic compound powder will be characterized by various analytical instruments to track the origin of physcicochemical property and to explain its thermal characteristics at the elevated pressure. The influence of the simulated overpressure on the generation mode of the gaseous inhibiting species will be obtained. Secondly, the explosion overpressure can be carefully regulated during the experiment by precisely choosing the location window and the time moment window into which the suppressant.powder will be discharged. The dependence of the gas explosions inhibition effectiveness on the actual overpressure will be established. Subsequently, the suppression mechanism of the catalytical compound powder on in-duct gas explosions by considering the overpressure action will be deduced. The proposal is expected to not only provide novel interpretation for the suppression mechanism of gas explosions in duct and enrich the theory of explosion suppression, but also provide new information to the development of the environment-friendly and highly effective suppressant powder and the design of the active explosion suppression system.

瓦斯抽采保障煤矿安全，提供清洁能源。然而，我国矿井瓦斯抽采量70%属于低浓度瓦斯，在输送过程中存在爆炸隐患。以粉体为抑爆剂的主动式抑爆系统是瓦斯输送管道的保障手段之一。发展清洁高效抑爆粉体、提高抑爆效率是抑爆系统的内在需求。基于“物性与实验条件决定抑制机理、抑爆机理决定抑爆效率”学术思想，提出催化型复合粉体抑爆的思路，解决关乎抑爆机理认识的“超压作用机制”这一科学问题。针对“超压是响应，更是作用”这一新认识，探究模拟超压对粉体热分解特性的作用规律，建立气相抑制组分形成的加压作用模式；选取典型浓度的瓦斯和特征粒径的复合粉体，精密选择粉体施加的位置窗口和时间窗口、调控超压，建立抑制效率与真实超压的关联。在此基础上，结合粉体表征，揭示考虑超压作用的抑爆机理。研究成果，期望能为深化理解瓦斯抑爆机理提供新思维，丰富爆炸抑制理论；同时，为寻找绿色高效的抑爆材料、合理设计主动式抑爆系统提供新依据。

为了提高抑爆剂抑制效率，本项目制备了二茂铁复合粉体，并评价了抑制瓦斯爆炸的效率。结合粉体表征，探讨了复合粉体的抑爆机理。结果表明，少量二茂铁的复合使得二茂铁/碳化硅复合粉体具备部分气相催化化学抑制作用，FeO等中间产物进入⋅H 和⋅OH 的消耗循环中，相比较纯碳化硅其抑制效果大幅度提升。15%:85%为二茂铁/碳化硅复合粉体临界抑爆复合配比，低于该配比的复合粉体抑制作用较小，高于该配比的复合粉体抑制效果大大增强，且在高浓度范围（320g/m3）内其相互之间超压抑制效果相差不明显。对于15%:85%二茂铁/碳化硅复合粉体，在最佳抑爆浓度320g/m3处，超压峰值降低率达到55.9%，相比较纯碳化硅提升11.8%，与纯二茂铁仅低2.9%。随着二茂铁配比由10%增至50%，二茂铁与氢氧化铝复合粉体抑制瓦斯爆炸的效率呈增加趋势，以10%:90%复合粉体变化曲线为界限，低于10%:90%复配比例的二茂铁/氢氧化铝复合粉体抑制作用处在单一粉体二茂铁与氢氧化铝粉体之间。. 讨论了泄爆对干粉抑爆的影响，建立了粉体-湍流-抑爆逻辑关联。在中等阻塞比下(φ值在0.4~0.6之间)，粉体抑爆效率最好。机制是，泄爆面积影响未燃气的湍流状态，干粉-湍流-火焰之间的相互作用控制着干粉抑爆效率。. 发现了抑制瓦斯爆炸的粉体临界直径。相同的表面平均粒径D32或比表面积SSA下粉体分布状态可能不同，导致不同的抑爆效率。不能仅以D32评价粉体性能，也应考虑粉体的粒径分布。粉体中小颗粒粉体所占的比例越高，粉体的抑爆效果越好。基于“小颗粒控制着抑爆效率”这一，获得了粉体临界直径（NaHCO3的临界直径dc=31.1μm）。. 提出了干粉抑爆“浓度效应”新解释。假想干粉颗粒的热分解行为类似于可燃液滴的蒸发行为，将干粉颗粒云的热分解划分为单颗粒分解模式和颗粒云外鞘分解模式。在低浓度下，干粉云更接近单颗粒分解模式，抑爆效率更好；在高浓度下，干粉云向颗粒云外鞘分解模式过渡，抑爆效率变差。