直流燃油MILD燃烧湍流介观特性研究

Mesoscopic Characteristics Analysis of Directly Oil MILD Turbulent Combustion

以尺寸φ410 mm×1 930 mm实验炉膛为对象,采用数值模拟的方法研究了燃油燃烧器参数(射流速度、射流间距、再循环烟气量、炉膛热负荷等)对炉内燃烧特性以及湍流介观特性的影响,根据湍流燃烧无量纲准则数判定燃油MILD燃烧模式。研究结果表明:当烟气再循环率为20%,空气高速射流速度为150 m/s,且空气喷嘴所在的圆环直径为炉膛直径的0.5~0.65倍时,炉膛内可建立燃油MILD燃烧模式,其火焰锋面的湍流介观参数位于湍流分区图中的良搅拌反应器区域,即l/l_F>1,Re_T>>1,Ka_δ>1,Da<1。燃油在MILD燃烧工况燃烧时,炉内温度峰值降低,氧浓度基本小于3%,炉膛出口NO_x排放浓度小于80 mg/m^3(标态)。

Simulated mes0scopic characteristics of directly oil MILD turbulent combustion by pilot furnace of 4〉410 mm ×1 930 mm, the oil burner parameters are jet velocity, interval, flue gas recirculated amount and heat load. Combustion models are determined by no dimensional criterion numbers of turbulent combustion. The resuhs show that oil MILD com- bustion will set up in the pilot furnace when flue gas recirculated rate is 20%, and normal air jet velocity is 150 m/s, and circle diameter installed at air nozzles is 0.5 - 0.66 times of furnace diameter. Mesoscopic parameters of high temperature zoon is in the distributed regime of turbulent combustion, and l/lF〉 1 ,RerT〉〉1 ,Kaδ〉 1 ,Da〈1. At oil MILD models the high- est temperature of furnace is lower, oxygen concentration is almost less than 3%, so the NO, emission is less than 80 mg/ m3 （standard）.