不同二次风角度的W炉冷态流场实验研究

Influence of secondary air angle on flow field in down-fired furnace determined by cold-flow modeling experiment

针对燃煤W火焰锅炉氮氧化物排放高的问题,提出新型W火焰锅炉燃烧技术——热风包裹低NOx燃烧技术(HAP),并对该技术进行冷态模化实验研究.HAP技术在常规W炉的基础上,在下炉膛增加了冷灰斗二次风和炉底二次风.冷态模化实验表明:相比于常规的W锅炉,HAP技术的炉内流场更优化,一次风下探深度大,炉内充满度高,并且壁面未出现严重的贴壁流动,结渣风险较小.通过对前后墙二次风和冷灰斗二次风的不同倾角的实验研究发现:倾角为45°的前后墙二次风具有较好的下探深度和炉膛充满度,避免了贴壁流动现象;增大冷灰斗二次风入射角度可以减小一次风下探深度,使得贴壁流动现象加剧.炉膛充满度随着冷灰斗二次风倾角的逐渐增大呈现先增大后减小的趋势,在66°时达到最大值.

Focusing on the problems of high NOx emissions in down fired boilers, a new combustion tech- nology was presented for down fired boilers, hot air packing low-NOx combustion technology （HAP）, and its cold-flow modeling experiments were conducted. HAP technology adds the secondary hot-air ports in the furnace hopper and bottom on the basis of the prior down fired boiler. The cold-flow modeling experi- ments prove that HAP technology has a much better airflow distribution compared with the prior W flame technology in the lower furnace. HAP technology produces a deeper penetration depth of the primary air and a higher filling fullness of air flow in the lower furnace. The adherent air flow towards the furnace wall does not appear obviously, which implies little risk of slagging. Different injection angles of the front and rear walls＇ secondary hot-air and the hopper secondary hot-air were researched. The wall secondary air with the injection angles of 45° makes a deeper penetration depth, higher filling fullness of air flow and good adherent air flow. Penetration depth of the primary air decreased and adherent air flow became worse when increasing the angles of the hopper hot-air. The filling fullness of air flow increases firstly and reduces afterward with the increasing angles of the hopper hot-air, and reaches a maximum when the angle is 66°.