常规煤粉作为再燃燃料的燃料分级燃烧试验研究

引对燃料分级燃烧技术在我国处于发展阶段．目前国内还没有工业应用的成果和经验这一状况，进行了常规煤粉作为再燃燃料的燃料分级燃烧试验研究．其目的是通过试验了解和掌握燃料分级燃烧技术，并为电厂锅炉燃料分级燃烧技术积累经验．华能长兴电厂用常规煤粉(R90=20％)作为再燃燃料进行的燃料分级燃烧试验是以锅炉3层燃烧器下面的2层燃烧器作为主燃区的燃料喷口，通过控制给粉机转速使主燃区的给粉量约80%，最上层燃烧器作为再燃区燃料喷口，再燃区的给粉量约20%，原三次风喷口则作为燃尽风喷口；调整和关闭不同位置的二次风门开度，使锅炉炉膛燃烧形成下面为主燃区（空气过剩系数为1.0）、中间是再燃烧区（空气过剩系数为0.88）和上面为燃尽区（空气过剩系数为1.2）的3个燃烧区段，实现燃料分级燃烧。通过工业试验得到电厂锅炉在现有条件下采用常规煤粉作为再燃燃料可使烟气中NOx排放值降低约20%。

Study on fuel-staged combustion with conventional pulverized-coal as refuel

Fuel-staged combustion technology is in its developing stage in China. There is no industrial application results and experience. The Huaneng Changxing Power Plant carried out a research in this field with conventional pulverized-coal (R90=20%) as refuel in order to get some knowledge for its application on utility boilers. The experiment took two lower-layer burners of the three layers as fuel nozzles in main combustion zone and maintained a coal feeding of about 80% in this zone by controlling the rotational speed of the feeder. The top layer burners were used as fuel nozzles in reburning zone and the coal feeding was about 20% in this zone. The original tertiary air nozzles were used as overfire air nozzles. By adjusting the valve lift of secondary air nozzles in different positions, the main combustion zone formed in lower furnace (excess air ratio 1.0), reburning zone in the middle part of the furnace (excess air ratio 0.88) and overfire zone in upper furnace (excess air ratio 1.2), thus realized fuel-staged combustion. The experiment shows that by using conventional pulverized-coal as refuel in existing utility boilers, NOx emissions in flue gas can be reduced by 20%.