基于CFD计算的管式加热炉燃气分级低NO_x燃烧器研究

Study on Fuel Staged Low-NO_x Burner of Tube Furnace Based on CFD

以某石化公司低NO_x燃烧器改造项目中管式加热炉内0.7 MW扩散式燃气燃烧器为研究对象,提出了两种低NO_x改进方案。方案A采用传统燃料分级供给形式,方案B在采用燃料分级供给的同时还采用了特殊耐火砖结构。应用计算流体力学(CFD)软件Fluent对燃烧器两种改进方案的燃烧过程和NO排放进行了数值模拟,获得燃烧室内温度分布、组分分布、NO生成速率以及火焰形态等参数。比较计算结果发现,燃烧器方案B的结构能够合理地组织燃烧区的流场,改善火焰形态,提高火焰传热效率,防止局部热点的形成,使温度分布更均匀。与方案A相比,方案B的峰值温度降低了233K,出口处NO的平均体积分数降低了19.3μL/L,抑制NO排放的效果更好。

Taking the 0. 7 MW non-premixed gas burner of tube furnace in the low-NOx reform project of a petrochemical company as the research object, we put forward two different kinds of improved burner models. The model “ A” adopted traditional fuel-staged form. The model “ B” not only adopted fuel-staged form but also comprised a special refractory brick. Then numerical simulations of the combustion process and NO emission were carried out by using CFD （Computational fluid dynamics） software Fluent. Some related parameters were obtained, such as temperature and component distributions, NO production rate, flame shape and so on. By comparing the results, it turned out that the structure of the burner model “ B” organized combustion flow field properly and scientifically, which improved the flame shape and enhanced the heat transfer efficiency of flame. It helps to avoid the formation of local overheated spot and creates a more uniform temperature distribution. Compared with the other one, the maximum temperature of the model“ B”decreased by 233 K and average volume fraction of NO at exit decreased by 19. 3μL/L , which means that NO emission was reduced more efficiently.