运行优化降低燃煤锅炉NO_x排放的试验研究

Experiment Investigation on Reducing NO_x Emission of Coal-fired Boiler by Optimizing Operation

在一台1025t/h的烟煤锅炉上进行了NOx排放特性研究。试验主要研究了炉膛出口氧量、顶部燃尽风及其喷嘴摆角、燃烧器组合、辅助风配风及锅炉负荷对NOx排放的影响。试验结果表明,NOx排放随炉膛出口氧量降低而明显降低,中下层燃烧器运行的NOx排放明显低于中上层燃烧器运行或隔层运行,缩腰型配风方式可明显降低NOx排放。由于顶部燃尽风与主燃烧器距离太近且设计燃尽风量偏小,燃尽风喷嘴和摆角对NOx排放影响较小。经过运行优化调整,烟煤锅炉NOx排放可降低30%以上,低于500mg/m3。

Experiments investigation on NOx emission characteristic in a 1025t/h bituminous coal-fired boiler are described in detail. Particular, the effects of combustion conditions, such as excess air ration at exit of furnace, OFA and its tilt angle, auxiliary air, different combinations of burners as well as load swinging on NOx emission in exhaust gas, are studied. It is found that the NOx emission decreases greatly with excess air ration decreasing, and lower burners operating is better than upper burners operating or middle burners shut down. In addition, ＂X＂ type distribution of auxiliary air can also decrease NOx emission. Because of short interval between OFA and main burners and low ration of OFA in this boiler, it has less influence on NOx emission than we estimating. After optimizing operation, the NOx emission of this boiler decreases obviously to below 500mg/m^3.