旋流燃烧器高负荷灭火问题研究

Study on flame stability of swirl coal burner at high load

针对某670t/h燃用贫煤锅炉旋流煤粉燃烧器在额定负荷出现的灭火问题,在单相试验台上进行了冷态模化试验。试验结果表明:高负荷下的灭火不是由于射流回流区及扩展角的变化引起的,而是由于旋流二次风速过高,导致一、二次风风速不匹配引起的。去掉燃烧器旋流二次风道与直流二次风道之间的扩口后,旋流二次风速度下降,旋流二次风较早地向外扩散,射流的回流区及扩展角略有增加。工业试验表明:采用改进后的燃烧器结构解决了高负荷灭火问题。同时,还分析了直流二次风率、旋流二次风、一次风对流场的影响。

Since the swirl coal burners could not keep the flame stable at rated load in a 670 t/h lean coal-burned boiler, cold flow experiments were made in a single-phase test-bed. The experimental results showed that, the flameout at high load arose not from the changes of re-circulation zone and divergent angle, but from the mismatched primary air and swirl secondary air. When the cones between the swirl secondary air duct and the non-swirl secondary air duct in the burners were removed, the swirl secondary air velocity decreased and diffused around earlier, and the re-circulation zone length and divergent angle increased somewhat. The improved burner can resolve the flameout problem at high load. The impact of non-swirl secondary air ratio, the swirl secondary air ratio and the primary air on the flow field are also achieved.