冶金加热炉燃料分级低NO_(x)燃烧器燃烧特性数值分析

Numerical analysis of combustion characteristics of low NO_(x) burner with fuel classification in metallurgical heating furnace

借鉴航空发动机燃烧技术原理,设计了一种冶金用燃料分级高速低NO_(x)燃烧器。对比了原型燃烧器与单开A、B两类二级枪的燃烧器对燃烧过程的影响,并对原型燃烧器在5种负荷(100%、80%、60%、40%和20%)及5组不同过量空气系数(0.9、1.0、1.1、1.2和1.4)的炉内燃烧过程进行了数值分析。模拟结果表明:新型低氮燃烧器分级结构设计合理,两类燃料二级枪的组合设计对NO_(x)排放的抑制作用十分明显;燃烧器在不同工况下均能保证良好的燃烧特性,并且能够有效抑制NO_(x)排放,NO_(x)质量浓度均低于65 mg/m^(3)(8%O_(2)体积分数折算);随燃烧器负荷的降低,NO_(x)质量浓度逐渐增加,当提高或降低过量空气系数时,燃烧处于富燃和贫燃两种情况,NO_(x)的生成均会减少。对于该型燃烧器而言,燃烧器负荷控制在40%以上,过量空气系数控制在1.2附近,可以有效的减少NO_(x)的排放。

Drawing on the principle of aero-engine combustion technology, a high-speed and low-NO_(x) burner for metallurgical fuel classification is designed. The effects of the prototype burner and the burners of the single-open A and B two-stage guns on the combustion process were compared. The prototype burner was tested at five loads(100%, 80%, 60%, 40%, 20%), and the combustion processes with 5 groups of different air excess coefficients(0.9, 1.0, 1.1, 1.2, 1.4) under full load were numerically analyzed. The simulation results show that the hierarchical structure design of the new low-nitrogen burner is reasonable, and the combined design of the two types of fuel secondary guns has a very obvious inhibitory effect on NO_(x) emissions;the burner can ensure good combustion characteristics under different working conditions, and can effectively suppressing NO_(x) emission that the NO_(x) concentration is lower than 65mg/m^(3)(8% O_(2) concentration conversion);with the decrease of the burner load, the NO_(x) concentration gradually increases;when the air excess coefficient is increased or decreased, the combustion is in rich combustion or lean combustion, and in any case, the generation of NO_(x) will be reduced. For this type of burner, if the burner load is controlled at more than 40%, and the excess air coefficient is controlled at around 1.2, NO_(x) emissions can be effectively reduced.