基于MILD燃烧模式的城市生活垃圾反应特性和NO形成机制的研究

MILD combustion technology has been widely used in various types of power plants, reflecting the uniform distribution of heat flow, low combustion peak temperature and ultra-low emissions of pollutants and other advantages. In this project, the MILD combustion mode is applied to the municipal solid waste incineration system by using the self-made vertical furnace combustion system. The experimental data measurement and the numerical simulation with simplified chemical reaction model are used. Through varying the Reynolds number of the solid fuel and the distance between fuel nozzle and hot flue gas nozzle, the apparent characteristics of the MILD combustion system are analyzed, and the coupling characteristics of gas-solid heat transfer between volatiles release rate and particle flowing regime under MILD combustion mode are explained. The effects of the turbulence on suppression mechanism of the heterogeneous reaction and promotion mechanism of NO reburning characteristic are described. meanwhile, the release characteristics mechanism of the volatiles under MILD combustion mode is clarified, and the effects of the turbulence on CO production characteristics and NO formation characteristic are revealed. So the research on the reaction characteristics and NO formation mechanism of the municipal solid waste under MILD combustion mode are completed. The research results of this project will extend the application of MILD combustion mechanism and provide a solid theoretical basis for the reasonable parameters design of MILD combustion system of municipal solid waste.

MILD燃烧技术已较为广泛地应用于各类动力设备中，体现出热流分布均匀、燃烧峰值温度低及污染物排放含量超低等优越性。本项目拟利用自制的竖直炉燃烧系统，创新性地将MILD燃烧模式成功移植于城市生活垃圾焚烧体系中；采用实验数据测量和化学反应模型简化的数值模拟研究相结合的方法，通过改变固体燃料进口雷诺数和燃料及热烟气喷口距离等参数条件，分析生活垃圾MILD燃烧体系建立的表观特征，阐释MILD燃烧模式下挥发分释放速率与颗粒流态的耦合机理，描述湍流效应对非均相反应的抑制特性和对NO再燃烧特性的促进机制，从而明确MILD燃烧模式下挥发分的释放特性机理，揭示湍流效应对CO生成特性和对NO形成机制的影响机理，最终完成基于MILD燃烧模式下城市生活垃圾的反应特性和NO形成机制的研究。本项目的研究成果将会扩展MILD燃烧机理的应用范畴，对生活垃圾MILD燃烧系统参数的合理设计提供坚实的理论基础。

MILD燃烧技术已较为广泛地应用于各类动力设备中，体现出热流分布均匀、燃烧峰值温度低及污染物排放含量超低等优越性。本项目利用自制的竖直炉燃烧系统，通过系统结构参数(空气射流角度及喷口间距)和操作参数(空气射流速度、燃料射流雷诺数和空气进口温度及氧浓度等)的优化设计创造了烟气强卷吸环境，成功地将MILD燃烧模式移植于固体废弃物燃烧体系中。. 本项目采用实验数据测量和化学反应模型简化的数值模拟研究相结合的方法，在成功构建固体废弃物颗粒MILD燃烧体系基础上，分析了MILD燃烧体系所呈现的表观特征(该模式下炉内温度均匀性低于3%，出口NO浓度低于25ppm)。固体颗粒MILD燃烧模式的构建依赖于烟气再循环倍率与氧化剂进口温度和氧化剂中氧含量的耦合关系，即当再循环倍率满足条件时，氧化剂进口温度在常温时(23℃)，氧化剂中氧含量需低于8vol%，而当氧化剂进口温度在150℃时，氧化剂中氧含量则上升至25vol%，且烟气再循环倍率低于2.3时将无法实现MILD燃烧模式。此外，通过阐释挥发分的释放特性机理，揭示出烟气循环倍率即湍流效应对非均相反应的抑制特性和对NO再燃烧特性的促进机制。本项目的实施揭示出MILD燃烧模式下强湍流效应对CO生成和NO形成的影响机理，从而扩展了MILD燃烧模式的应用范畴。