多孔介质内自预热低浓度瓦斯驻燃特性及火焰微观机理

Coal mine methane (CMM) utilization is very important for coal mine safety, energy conservation and environment protection. However, the single porous media combustion technology is difficult to utilize CMM efficiently and stably due to the low concentration and the fluctuating working condition. According to the advantages of the CMM preheating with the high temperature flue gas in the improvement of combustion characteristics, a porous media burner with self-preheating structure based on packed bed is proposed in the project. Through the experimental methods of optical diagnostics and fine measurement, together with the non-equilibrium thermal simulation and theoretical analysis, the steady combustion of low-concentration CMM in the new porous media burner is studied. The objectives of the project are included in the followings. The steady combustion characteristics of the low-concentration CMM in the self-preheating porous media burner will be obtained after the building of optimization model between the heat exchanger structure, packed bed parameter and the CMM preheating degree. The project will explore the characterization methods of unstable dynamic evolution of flame front and the coupling mechanism between macroscopic dynamics characteristics and microscopic parameters during the steady combustion. Meanwhile, the flame features and the microscopic parameter distribution will be revealed during the steady combustion of low-concentration CMM in the self-preheating porous media burner. In order to obtain the optimal limit range of typical species content to keep the steady combustion, the influence of the typical species addition in the low-concentration CMM on the combustion mechanism will be studied. The research results of the project contribute to supplementing the porous media combustion theory and provide the basic reference for the efficient resource exploitation of low-concentration CMM.

瓦斯利用是促进煤矿安全和节能环保的重要举措，而由于抽采瓦斯浓度低、工况波动频繁，单一多孔介质燃烧技术难以高效稳定利用瓦斯。本项目根据高温烟气预热瓦斯在改善燃烧特性上的优势，提出一种基于堆积床自预热装置的多孔介质燃烧器。通过光学诊断与精细测量实验手段，结合非热平衡数值模拟和理论分析方法，开展新型多孔介质燃烧器内低浓度瓦斯的驻定燃烧研究。目的在于构建换热器结构、堆积床参数与瓦斯预热效果的优选模型，获得自预热型多孔介质燃烧器内低浓度瓦斯的驻定燃烧特性；探索驻定燃烧时火焰锋面非稳定性动态演化的表征方法和宏观动力学特性与微观参数之间的耦合机制，揭示多孔介质内自预热低浓度瓦斯的驻燃火焰特征及微观参数分布规律；阐明低浓度瓦斯中典型组分对其在多孔介质内自预热驻定燃烧机理的影响规律，获得维持驻定燃烧时典型组分含量的最优极限范围。研究成果将进一步完善多孔介质燃烧理论，为低浓度瓦斯资源化高效开发应用奠定基础。

煤矿低浓度瓦斯高效利用对提高煤矿安全和促进节能环保具有重要工程意义。本项目基于多孔介质高效传热传质特性，通过强化烟气热量回传达到了提高低浓度瓦斯利用效率的目的。项目研究过程中针对螺旋式、列管式、翅片式三种典型换热方式下流速和预热温度等参数演变进行模拟分析，研究了不同形状换热装置对预热效果的影响规律，以此搭建了自预热式多孔介质燃烧实验装置。通过数值模型、实验研究和理论分析等方法相结合，基于自预热式多孔介质内低浓度瓦斯燃烧实验系统，得到了气流预热对瓦斯燃烧特性以及污染物排放的影响规律，揭示了填充材料孔径参数与燃烧器内温度分布、冷态启动时间、燃烧温度和污染物排放的耦合关系，为多孔介质燃烧器设计提供理论依据。同时，提出了一种空心柱状结构堆积床，它充分结合了泡沫陶瓷与小球堆积床优点，并研究了其在预热情况下空心柱状结构的尺度效应对燃烧器内温度分布、稳定位置和污染物排放等宏微观参数的影响规律，相关研究对自预热式多孔介质燃烧器内填充结构选取具有指导意义。