燃烧过程中控制NOx生成是最直接经济有效的低NOx燃烧技术。煤粉预热-燃烧技术以其巨大的低NOx燃烧潜力逐渐得到重视。煤粉预热-燃烧技术降低NOx生成的主要思路在于：煤粉进入炉膛燃烧前，通过设置独立的高温低氧强还原性物理空间对煤粉进行预热，挥发分在预热区内快速析出并进行相应转化，促进挥发分N的释放并增加挥发分N还原为N2的比例，从而降低煤中N被氧化成NOx的概率；在此基础上，通过结合空气分级和MILD燃烧等低NOx技术对预热产物进行相应的燃烧组织，进一步降低预热产物燃烧过程中NOx的生成。现阶段煤粉预热-燃烧技术根据预热热源与装置的不同可以分为燃气辅热式煤粉预热-燃烧技术、流化床煤粉预热-燃烧技术、燃烧器煤粉预热-燃烧技术。其中燃烧器煤粉预热-燃烧技术通过优化设计，将煤粉自预热技术与径向及轴向多级逐级配风技术、燃料浓淡分离与分级送粉等技术有机结合，在保证高效低NOx同时，具备低成本与改造灵活性的优势。实际应用结果表明：燃烧器煤粉预热在运行稳定性、变负荷适应性及低NOx燃烧方面均表现出优异性能。

Reducing NOx formation during pulverized coal (PC) combustion process is the simplest and most efficient way to minimize NOx pollution. PC preheating and combustion technology has been paid more and more attention because of its great potential in low NOx combustion. The key idea of preheating-low NOx combustion is that before pulverized coal enters the furnace for combustion,the pulverized coal is preheated by setting an independent physical space with high temperature,low oxygen and strong reducibility,and the volatile is rapidly precipitated and transformed in the preheating area,so as to promote the release of volatile N and increase the proportion of volatile N reduced to N2,so as to reduce the probability of N in coal being oxidized to NOx. Meanwhile,by integrating low-NOx technology,such as air staging and MILD combustion,the formation of NOx is further reduced. So far,according to different preheating heat sources and preheating devices,PC preheating technology can be divided into gas-fired preheating,fluidized bed preheating and self-preheating burners. Among them,self-preheating burner organically combines the pulverized coal self-preheating technology with the radial and axial multistage step-by-step air distribution technology,fuel concentration and dilution separation and graded powder feeding technology through optimal design,which has the advantages of low cost and transformation flexibility while ensuring high efficiency and low NOx. The self-preheating burner shows excellent operation stability,load adaptability and low NOx production by integrating self-preheating,multi air staging,fuel-rich/lean separation and fuel staging technology. 

0 引言

1 燃气辅热式煤粉预热-燃烧技术

2 流化床煤粉预热-燃烧技术

3 燃烧器煤粉自预热-燃烧技术

4 结语与展望