低氮燃烧器改造目的：燃烧器及配风方式在改造后，主要是为了实现了炉膛内部真正的浓淡分离和浓相相对集中达到炉内燃烧梯度分级要求，实现最初的降低NOx和着火稳定性目的。但改造后存在前屏易超温、热偏差较大、再热汽温偏低以及单C制粉系统运行主再热汽温均偏低的现象。且采用的低氧分级燃烧技术对锅炉的稳燃有一定的影响。
Low nitrogen burner alteration purpose: burner and air distribution mode after the transformation, mainly in the chamber of a stove or furnace in order to realize the real separation and thick shade relatively concentrated to furnace combustion phase gradient classification requirements, realize the original reduce NOx and ignition stability purposes. However, after the modification, there are some phenomena, such as easy overtemperature of the front screen, large thermal deviation, low reheating steam temperature and low main reheating steam temperature of the single C powder making system. The technology of low oxygen combustion has certain influence on the steady combustion of boiler

1、低氧燃烧控制氮氧化物与稳定燃烧分析
1. Low oxygen combustion control nitrogen oxides and stable combustion analysis

根据低氮燃烧的要求，炉膛的主燃烧区域减小过量空气系数，进行贫氧燃烧，降低主燃烧区域的炉温，来抑制氮氧化物的生成。但过低的氧量控制，使锅炉燃烧的稳定性及安全性大大折扣。以高负荷300MW为例，将总风量由改造前的80%降至70%～75%，调整关小主燃烧区域的辅助风挡板，SOFA1-3层采用SOFA1：80%;SOFA2：100%SOFA3：100%配风方式，与之前的大风量，SOFA风挡板不开或小开度相比，SCR入口氮氧化物有了显著下降，但此种配风方式下炉膛抗扰能力下降，炉膛风箱差压只能维持在600pa左右，严重偏离该炉改造前给定的优化值850pa以上。在风烟系统主要辅助设备出现故障时及煤质突变时，很可能造成灭火，所以安全起见，只能适当增加氧量或者关小上层SOFA风挡板。
According to the requirement of low nitrogen combustion, the main combustion area of the furnace reduces the excess air coefficient, carries on the oxygen-poor combustion, reduces the furnace temperature of the main combustion area, and inhibits the formation of nitrogen oxides. However, the stability and safety of boiler combustion are greatly reduced by too low oxygen content control. Taking the high-load 300MW as an example, the total air volume was reduced from 80% before the renovation to 70% ~ 75%, and the auxiliary air baffle in the main combustion area was adjusted to be small. SOFA3 SOFA2:100% : 100% air distribution mode, and before the big air volume, SOFA than wind baffle doesn't open or small open degree, SCR nox entrance was decreased significantly, but the air distribution mode of a stove or furnace anti interference ability, bellows differential pressure chamber of a stove or furnace can only remain at around 600 pa, gravely deviates from the furnace before modification of the given optimal value more than 850 pa. In case of failure of the main auxiliary equipment of the smoke system and coal quality mutation, it is likely to cause fire extinguishing, so it is safe to increase the oxygen content or turn down the upper SOFA air baffle properly.

2、分级梯度燃烧控制氮氧化物与稳定燃烧分析
2. Graded gradient combustion control nitrogen oxides and stable combustion analysis

此次改造从燃烧方面控制氮氧化物的排放上讲，改造范围较小，实际控制上只能实行水平浓淡燃烧加配风调整手段，低负荷运行时仅仅能满足稳定燃烧，燃烧效率上讲又有所下降。负荷较高时，燃烧稳定，抗扰能力较强，分级梯度燃烧可以发挥明显作用。低负荷以负荷150MW为例，总风量控制在45%～50%由于炉膛风箱差压的限制，上层sofa风开度不能很大，每层开度的大小将影响汽温的热偏差，严重时达到40度，且任一层SOFA风开大至50%以上后，会造成B层火检短闪，严重影响燃烧的稳定性。所以从客观上讲，150MW负荷基本上是用SOFA风来调整热偏差，分级低氮燃烧的基本未能实现。氮氧化物此时只是跟氧量量控制的大小有明显的关系。
The transformation from the aspects of the combustion control of nox emissions, smaller scale, the actual control can only implement horizontal shading burning on air distribution adjustment means, runtime only can satisfy the steady combustion under low load, the combustion efficiency and decreased. When the load is high, the combustion is stable and the anti-disturbance capability is strong. Low load to load of 150 mw, for example, total air volume control in 45% ~ 50% because of the limitation of bellows differential pressure chamber of a stove or furnace top sofa opening can't wind is very big, each layer of the opening will affect the size of the steam temperature of thermal deviation, serious when reach 40 degrees, and any layer after sofa wind up to more than 50%, will cause the B layer short flash of flame detector, seriously affecting the stability of combustion. Therefore, objectively speaking, the 150MW load is basically SOFA wind to adjust the thermal deviation, and the graded low nitrogen combustion is basically not realized. Nitrogen oxides are only significantly related to the amount of oxygen they control.

低负荷(180MW以下)SOFA风在分级燃烧中的效果不大，主要是根据制粉系统运行方式不同来调整汽温的热偏差，随着负荷(180～220MW)的增加，SOFA风开度不断加大，分级梯度燃烧也越来越明显。为保证实验数据对比最大化，现已300MW负荷为例。按分级梯度燃烧最优化调整，取参数：SOFA风1～3三层开度分别为：50%100%100%总风量72%，SCR入口氮氧化物测量值为506mg/m3，主再热汽温536度、535度。关闭上层SOFA风开度，调整开大下层辅助风挡板稳定运行20分钟，发现SCR入口氮氧化物上升至680。两种调整方式，炉膛火焰金黄色，火检正常，但氮氧化物有明显的区别，所以高负荷是SOFA风的开大可以有效的抑制氮氧化物的排放。

(180 mw) under low load SOFA in the classification of burning wind effect is not big, mainly according to the coal pulverizing system running in a different way to adjust the steam temperature of thermal deviation, with the increase of load (180 ~ 220 mw), the SOFA of the opening of the wind rising, grading gradient combustion is becoming more and more obvious. In order to maximize the comparison of experimental data, 300MW load has been taken as an example. The parameters were: SOFA wind 1 ~ 3 opening degrees were: 50%100%100% total air volume 72%, SCR inlet nox value was 506mg/m3, and the main reheat vapor temperature was 536 degrees and 535 degrees respectively. The upper SOFA wind opening was closed, and the lower and larger auxiliary air baffle was adjusted to run stably for 20 minutes. It was found that the nitrogen oxides in the SCR inlet increased to 680. The two modes of adjustment, the furnace flame is golden yellow and the fire test is normal, but there is a significant difference in nitrogen oxides, so the high load is the opening of SOFA wind can effectively inhibit the nitrogen oxides emissions.