摘要: 基于循环流化床预热燃烧工艺，研究氮气浓度对预热燃料成分的影响规律。结果表明，在预热过程中，氮气浓度会对提升管各处的温度产生较大影响； 对后置燃烧室内的预热燃料温度影响较小；进入后置燃烧室内的煤气热值有较大降低，这一变化会影响燃烧稳定性，甚至导致熄火现象。同时发现，随着氮气浓度增加，各组分转化率都随之降低，说明了流化床内化学反应变缓；超过40%的燃料氮发生了转化，这部分氮转化对于实验系统的NO_x排放具有关键性作用。

关键词: 氮气浓度；半焦；预热燃烧；循环流化床

Abstract: Based on preheating process of circulating fluidized bed ( CFB) ，the characteristics of preheated fuel under different nitrogen concentration were studied．It is obtained that nitrogen concentration in the preheating process has a greater impact on the temperature of the riser，but it has few impact on the temperature of the preheated fuel at the exit of the cyclone，that is，the temperature of preheated fuel flowing into the rear downstream combustion chamber．The low heating value of preheated gas decreased greatly，which affected the combustion stability，even led to the flameout．Simultaneously，it is obtained that with the increase of nitrogen concentration，the conversion rate of each component decreases，which directly reflects that the increase of nitrogen concentration slows down the chemical reaction rate in the fluidized bed．In addition，above 40% of fuel-nitrogen had been transformed in the preheating process，which played a key role in the NO_x emission of the test system．

Keywords: nitrogen concentration; char; preheating combustion; circulating fluidized bed