一次风风速对高温预热空气下的煤粉MILD燃烧的影响

Effect of Primary Air Stream Velocity on MILD Combustion of Pulverized Coal in High Temperature Preheated Air

本文研究了一次风风速对高温预热空气下的煤粉MILD燃烧的影响。首先通过与国际火焰研究基金会(IFRF)的煤粉MILD燃烧实验数据对比,验证了数值模拟方法的可行性。然后在不同一次风入射角(0°、+5°和-5°)下,保持一次风风量不变,通过改变管径将风速从26 m/s增至48 m/s。研究发现,当一次风与二次风平行(0°)或背离(+5°)入射时,提高一次风风速会使炉内的峰值温度下降;当一次风朝向(-5°)二次风入射时,提高速度会使炉内温度峰值先下降后升高。总体而言,一次风与二次风背离入射时,温度峰值最低;一次风朝向二次风入射时,温度峰值最高。

The present work numerically investigates the effect of injection velocity of the primary stream on MILD(Moderate or Intense Low-Oxygen Dilution) combustion of pulverized coal in high temperature preheated air.The modelling is verified by the in-furnace measurements of IFRF(International Flame Research Foundation).At an identical mass flow rate of the primary stream,the injection velocity(v_(pri)~*) is varied from 26 to 48 m/s with different incident angle(α=0°,+5° and —5°).Results reveal that when α = 0° and +5°,increasing v_(pri)~* leads to a decrease of the peak temperature;when α= —5°,increasing v_(pri)~* from 26 to 36 m/s reduces the peak temperature,and a further increase of v_(pri)~* to 48 m/s results in a higher peak temperature.Generally,the peak temperature with a =+5° is lowest,while that with α = —5° is highest.