单颗粒固体燃料燃烧火焰光谱特性研究

Study on Spectral Characteristics of Combustion Flame of Single Particle Solid Fuels

燃烧是固体燃料热利用的主要方式,掌握固体燃料燃烧过程动态特性对提高热转化效率及设备的安全运行有重要意义.本研究将激光诱导击穿光谱技术(LIBS)应用于单颗粒固体燃料不同气氛条件下的燃烧产物(包括H,O,N,CN,Na,K)的变化特性研究,同时获取激光击穿产物后穿过火焰的残余能量,结合高速相机获取的固体燃料点火图像,分析燃烧气氛对脱挥发分、挥发分燃烧及焦炭燃烧阶段的影响及富氧燃烧条件下燃烧特性的变化对碱金属释放的影响机制.结果表明,最大挥发分体积分数与气相着火时间有关,O_(2)/CO_(2)气氛下生物质燃料挥发分析出速率更快,CO_(2)除了本身与K的化合物结合转化为更难挥发的K2CO3使释放量减少外,还会降低火焰温度进而减少碱金属的释放.

Combustion is the main approach for the heat utilization of solid fuels,and it is significant for understanding their dynamic combustion process to improve the heat transfer efficiency and safe operation of the equipment.In this paper,laser-induced breakdown spectroscopy(LIBS)was applied to the dynamic analysis of combustion products of single particle solid fuels under different atmospheres,including H,O,N,CN,Na and K.The residual laser energy transmitted through the flame and the image of the solid fuel flame obtained using a highspeed camera were combined to investigate the effect of combustion atmosphere on the devolatilization,volatile combustion and the char burning process.In addition,the impact of changes in combustion characteristics on the alkali release at oxy-fuel atmosphere was also focused.Results indicated that the maximum volatile concentration during the ignition process is relevant to the gas-phase ignition time,and the volatile release rate of biomass fuel is higher in the O_(2)/CO_(2) environment.CO_(2) not only forms the less volatile K2CO3 through the recombination reaction with K,but also decreases the flame temperature to reduce the release rate of alkali.