超低挥发分燃料预热的富氧无焰燃烧热平衡动力学机理实验研究

The oxy-MILD combustion is a high efficient technology characterized by low oxygen dispersion, high burnout ratio, high heat flux uniform distribution and lower NOX emission cleaner combustion. Although a rapid development of oxy-MILD is achieved in both laboratory- and pilot-scale experimental systems, it is still far from clarification on the novel approach, and its intrinsic mechanisms of quasi-static thermochemistry equilibrium and chemical kinetics of oxy-MILD stabilized establishment for ultra-low volatile fossil fuel. Especially, it is unclear that both intrinsic mechanisms of thermochemistry equilibrium and competitive kinetics reaction are mainly contributed by char oxidation and gasification reactions in the establishment of flameless oxyfuel combustion. This project aims to develop the experimental study of the quasi-static thermochemistry and chemical kinetics mechanisms of oxy-MILD establishment for the ultra-low volatile fossil fuel with fluidized preheating physicochemistry modification, meanwhile exploring novel reaction pathways and ultimate limit for this advanced denitrogenation treatment. By detailed fundamental experiments and constructing theory model, both thermochemistry equilibrium function and chemical reaction kinetics pathway are connected. It is promised to understand the combustion chemistry mechanism of the stabilized oxy-MILD establishment with a wider range of boundary region for the ultra-low volatile fossil fuel. Research and development of oxy-MILD thermochemistry and chemical kinetics mathematical model are carried out for ultra-low volatile fossil fuel. The purpose is to achieve both fundamental experimental data and theoretical basis to understand the basic turbulent combustion chemistry mechanism of oxy-MILD combustion for fossil fuel, and furthermore to provide theory support to the development of industrial utilization of oxy-MILD combustion.

富氧无焰燃烧是一种高效的燃料低氧弥散、高燃烬、热流均布、低NOx的温和燃烧方式，有望成为下一代可承接的新型洁净燃烧技术。尽管多燃料富氧无焰燃烧技术在实验室和中试尺度研究获得了快速发展，但超低挥发分燃料富氧燃烧无焰稳定建立的新途径及其内在热化学平衡-反应动力学机理远未澄清，特别是富氧燃烧无焰建立的焦炭气化和氧化为主的准静态热化学平衡机制及其内在交互竞争性反应动力学机理仍未揭示。本项目仅针对流态化预热改性超低挥发分燃料开展富氧燃烧无焰建立的准静态热化学平衡及其反应动力学机理实验研究，同时挖掘其深度脱氮新路径和极限边界，通过详细基础实验和理论模型构建，关联热化学平衡函数和反应动力学路径，有望揭示超低挥发分碳基燃料宽边界域稳定建立的内在燃烧化学机理，并探索发展适用于超低挥发分燃料富氧无焰燃烧的热动力学模型，为富氧无焰燃烧湍流化学反应机理认识提供基础数据，更为富氧无焰燃烧工业应用提供理论支撑。

富氧燃烧中高浓度二氧化碳会对化石燃料燃烧产生极大的物理化学效应，改变燃烧过程的热动力学机制，无焰实现过程中高速射流动量比和强卷吸烟气构造受限空间内无明显高温区和可视火焰传播锋面的燃烧体系。常规富氧无焰燃烧具有高燃烬、低NOx排放的特点，流态化预热超低挥发分燃料的富氧无焰燃烧则将富氧燃烧、无焰燃烧与流态化预热三者技术优点进行结合，气化改性后的超低挥发分碳基燃料、二元燃料富氧无焰燃烧具有更深度降低NOx和CO排放效果，其流态化预热燃料改性机制及氮氧化物生成转化机理有待进一步深入研究。. 本研究对流态化超低挥发分预热燃料改性机制、二元燃料富氧无焰燃烧氮析出转化路径以及准静态热力学平衡模型进行了深入研究。在多种气氛下从微观和宏观多个层面对超低挥发分燃料及其对比燃料的流态化改性特性进行了对比分析，结果表明流态化富氧预热对于超低挥发分燃料具有远优于空气气氛的物化改性能力。此外，在流态化富氧预热燃烧过程中通过等空气烟气体积计算方法，可知半焦与无烟煤最低NO排放能够达到49.11mg/m3和49.97mg/m3。借助详细化学反应动力学对流态化预热-二元燃料富氧燃烧过程中氮析出转化路径进行探索分析，获得了多种典型参数对燃料氮迁移转化的影响规律以及反应数体量为详细含氮机理23%的简化机理。搭建了富氧流态化预热平衡模型，实现富氧流态化预热煤气组分水平及变化趋势的预测，加深对富氧流态化过程机理的认识。同时，构建新型焦炭富氧燃烧反应动力学模型，丰富了多种富氧气氛下流态化预热焦炭燃烧反应动力学交互效应及机制的认识，提升在中高温条件下对焦炭富氧燃烧过程规律模型预测精度和适应性。. 本项目研究阐明了超低挥发分碳基燃料流态化预热定向改性机制，揭示了预热改性的二元燃料燃烧动力学平衡和燃料氮迁移转化路径，加深焦炭在富氧条件下的燃烧反应动力学认识，完善了超低挥发分燃料流态化富氧无焰燃烧基础体系，为超低挥发分燃料的富氧燃烧技术和工业应用提供了基础性参考。