不同稀释剂对燃气锅炉NO_x排放及燃烧稳定性的影响

EFFECT OF DIFFERENT DILUENTS ON NO_x EMISSION AND COMBUSTION STABILITY OF BOILERS FUELED BY NATURAL GAS

结合试验与数值模拟,对比分析了过量空气、烟气、水蒸气3种稀释剂对天然气锅炉扩散燃烧过程中的NO_x排放及燃烧稳定性影响。结果表明:随着稀释剂吸热功率的增加,NO_x生成量减少。添加等同吸热功率的过量空气、烟气、水蒸气时,NO_x生成量依次减少,在3种稀释剂吸热功率达到250 k W时,NO_x生成水平分别为78,30,20 mg/m3;继续增加稀释剂添加量,燃烧稳定性变差。采用烟气再循环技术,在燃烧稳定极限点的NO_x排放浓度随过量空气系数增大先下降后保持不变;而采用加湿燃烧技术,在稳定极限点的NO_x排放度随过量空气系数升高而升高。

Combined with test and numerical simulation,the effect of excess air,flue gas and water vapor on the NO_xemission and combustion stability of the natural gas boiler during the diffusion combustion process were compared and analyzed. The results showed that with the increase of the heat absorption power of the diluent,the amount of NO_xproduction was reduced.When the excess air,flue gas and water vapor with the same endothermic power were added,the NO_xwas decreased successively. When the heat absorption power of the three diluents reached 250 k W,the NO_xproduction levels were 78,30,20 mg/m3,respectively. After adding the diluent,the combustion stability was deteriorated. With the flue gas recirculation combustion technology,the NO_xemission concentration at the stability limit first decreased,and then remained unchanged with the increase of the excess air coefficient. While under the humidification combustion technology,the NO_xemission degree at the stability limit point increased with the increase of the excess air coefficient.