直缝式燃烧器W火焰锅炉新型二次风箱特性研究

Characteristic research of a new type of secondary-air-box on a W-flame boiler with slit type burner

为解决直流缝隙式燃烧器W火焰锅炉原设计的全通二次风大风箱由于锅炉炉膛宽度宽、风箱截面尺寸大等原因产生的炉膛中部缺风问题,华能上安电厂将4号锅炉原风箱改造为分隔型新型二次风箱。新型二次风箱改造完成后对其特性的试验研究表明,常规冷态通风时拱上、拱下各喷口及各风道区域之间风速偏差较小。单侧送风机运行且联络门关闭时,送风机停运侧各喷口风速明显低于送风机工作一侧,但通过拱上、拱下二次风门的调整,能有效缓解由于单侧送风机运行带来的喷口风速偏差。单侧送风机运行联络门开启的情况下,3个风道区域平均风速的偏差与正常双送风机运行时差别不大。与改造前相反,锅炉运行炉膛出口氧量已呈现中间高两头低的趋势,适当调整二次风箱风门开度后炉膛出口氧量分布趋于均衡,说明改造后的二次风箱风门能有效调节炉内二次风配风进而改变炉膛出口氧量分布。通过二次风箱风门开度的适当调整,能有效降低SCR入口NOx浓度,保证锅炉经济环保运行。

in order to solve the problem of air lack in the middle of the furnace which was caused by the wide width of the furnace and the large sectional dimension of the air-box in the original design of a W-flame boiler with slit type burner, a new separated type of secondary-air-box was modified from the original design of boiler No. 4 in Huaneng Shang＇an Power Plant. Characteristic test after the modification of the new type of secondary-air-box showed that the air speed deviation between the upper and lower arches and the air duct regions was smaller than conventional cold ventilation. When one side of the forced draft fans was run and the communicating door was closed, air speed at the stopped side was obviously lower than the side that forced draft fan was operated. The deviation of the air velocity near the nozzle could be effectively reduced through the adjustment of the secondary air doors on the upper and lower arches. In the case of opening the communicating door of single forced draft fan, the deviation of the mean air speed between the three duct regions was not far different from the operation of the double forced draft fans. On the contrary, the furnace outlet oxygen showed a trend of middle height and low both ends ; and the oxygen distribution in the furnace outlet tended to be balance after adjusting the opening of the secondary-air-box door indicating the secondary-air-box door can effectively regulate the air distribution of the secondary air in the furnace and change the oxygen distribution in the outlet of the furnace. It has been showed that the appropriate adjustment of the secondary-air-box door opening can effectively reduce the SCR inlet NO~ concentration and ensure the economic and environmental operation of the boiler.