烧结加湿燃烧对NOx排放影响的研究

为了减少烧结过程中NO_x排放,研究了燃料工艺参数与烧结加湿燃烧对NO_x排放的影响。结果表明,烧结烟气中NO_x主要由燃料带入,燃料氮元素含量决定了烟气中NO_x浓度高低,燃料配比从6%降至4%,NO_x浓度平均值从424 mg/m³降至339 mg/m³; 燃料中碳元素能促进NO_x还原反应,同时提供更多热量,促进铁酸钙生成,缩短烧结时间。相对常规烧结,加湿燃烧烧结可以增强料层还原性气氛,增强NO异相还原反应,降低NO_x浓度; 并提高燃料完全燃烧程度,加快垂直烧结速度,提升烧结矿成品率与转鼓指数; 在蒸汽流量0.024 kg/min的工况下进行烧结加湿燃烧,NO_x浓度平均值从357 mg/m³降至338 mg/m³,转鼓指数提高约1个百分点。

Influence of Combustion Air Humidification on NOx Emissions During Sintering

In order to reduce NO_x emissions during the sintering process, the effects of fuel processing parameters and combustion air humidification during the sintering on NO_x emissions were studied. The results show that the NOx in the sintering flue gas is mainly caused by the fuel, and the NO_x concentration in the flue gas is principally dependent on the nitrogen content in the fuel. When the fuel proportioning reduced from 6% to 4%, the average NO_x concentration can be reduced from 424 mg/m³ to 339 mg/m³; and the carbon element in the fuel can promote the reduction reaction of NO_x, thus providing more heat and promoting the formation of calcium ferrite, resulting in the shortening of the sintering time. Compared with the conventional sintering, sintering with combustion air humidification can enhance the reductive atmosphere of the material bed and the heterogeneous reduction of NO, while reduce the NO_x concentration. Besides, it can improve the complete combustion of fuel, accelerate the vertical sintering speed, as well as increase the yield of sintered product and drum index. Sintering with combustion air humidification with the steam flow rate of 0.024 kg/min, can result in the average NO_x concentration decreased from 357 mg/m³ to 338 mg/m³, and the drum index increased by about 1 percentage point.