燃尽风对锅炉燃烧及脱硝经济性的影响

Effect of over fire air on combustion performance and denitration efficiency of a coal-fired boiler

为研究燃尽风（OFA）技术对NOx生成量、燃烧及脱硝总成本的影响,以某300MW机组锅炉为对象,采用支持向量机法,建立了输入量为机组负荷、一、二次风量、各层二次风挡板开度以及OFA挡板开度等,输出量为NOx生成量、耗煤量、脱硝效率的关系模型。利用该模型分析在保持总风量不变的条件下,改变OFA挡板开度对燃烧及脱硝总成本的影响,并以实际运行数据对其进行验证。结果表明：机组在50%~75%以及87%~100%2个负荷段,随着OFA挡板开度增大,NOx生成量下降,耗煤量上升,燃烧及脱硝总成本略有上升;在75%~87%负荷段,随着OFA挡板开度增大,NOx生成量也呈下降趋势,而耗煤量基本保持不变,燃烧及脱硝运行成本略有下降。

To improve the unit economy,the effects of using over fire air （OFA）technology on NOx forma-tion,furnace combustion and denitrification costs were investigated.Taking a 300MW unit boiler as the re-search object,the support vector machine （SVM）theory was applied to establish a mathematic model.In this model,the input variables are unit load,the primary and secondary air volume,the opening degree of the secondary air damper in each layer and the OFA damper opening degree.The output variables are the NOx formation,coal consumption and denitrification efficiency.The change rules between the OFA damper opening degree and the costs of combustion and denitrification were studied,on the premise of a constant total air volume.Moreover,the calculation results were verified by the actual operation data.The results show that,in the 87% to 100% load stage and 50% to 75% load stage,the NOx formation decreased and the coal consumption increased with the increasing OFA damper opening degree,and the combustion and denitrification costs increased a little.In the 75% to 87% load stage,the NOx formation decreased while the coal consumption tended to be stable with the increasing OFA damper opening degree,and the combustion and denitrification costs decreased slightly.