摘要
由于回转窑-矿热炉工艺中存在工业炉窑的能耗与废弃物排放量大且余热余能利用率低等问题,利用其炉内烟气的余热、余能对提升RKEF工艺的能源利用效率以及削减污染气体排放等均具有举足轻重的意义。研究设计1款回转窑五通道燃烧器并将其用于炉气和煤粉混合燃烧,采用计算流体动力学方法对回转窑内的气固两相燃料混合燃烧过程进行数值研究,分析炉气燃料的加入对回转窑内温度场、燃烧特性以及NO_(x)排放的影响。研究发现:在煤粉中混入气体燃料,鉴于轴流风与二次风之间存在显著的速度差,致使高温二次风被轴流风裹挟卷入,进而形成外循环区,能够显著提升煤粉的燃烧速率,同时优化回转窑内部的温度分布格局;采用炉气-煤粉混合燃料进行燃烧时,回转窑内的峰值温度以及焙烧区温度均呈现下降趋势,即由于气体燃料的掺入促使煤粉燃烧进程提前启动,使得黑火头的长度明显缩短,焙烧带位置也更靠近燃烧器,致使火焰呈现出稳定的“棒槌状”外观;随着炉气燃料的加入,回转窑内的峰值温度和焙烧区温度均有所下降,有助于缓解结圈现象的发生;加入炉气燃料还能有效降低NO_(x)的排放,回转窑出口处的NO_(x)质量浓度从655 mg/m^(3)降至327 mg/m^(3),NO_(x)排放量减少了50.1%。
Due to the problems such as large energy consumption and waste emissions of industrial furnaces and low utilization rate of waste heat and residual energy in the rotary kiln-submerged arc furnace process,it is of great significance to utilize the waste heat and residual energy of the flue gas in the furnace for improving the energy utilization efficiency of the RKEF process and reducing the emission of polluted gases.A five-channel burner for the rotary kiln was designed and used for the mixed combustion of furnace gas and pulverized coal.The computational fluid dynamics method was adopted to conduct a numerical study on the mixed combustion process of gas-solid two-phase fuel in the rotary kiln,and the influence of the addition of furnace gas fuel on the temperature field,combustion characteristics and NO_(x)emissions in the rotary kiln was analyzed.The study found that when gaseous fuel is mixed into the pulverized coal,due to the significant velocity difference between the axial flow air and the secondary air,the high-temperature secondary air is entrained by the axial flow air,forming an outer circulation zone,which can significantly increase the combustion rate of the pulverized coal and optimize the temperature distribution pattern inside the rotary kiln.When the mixed fuel of furnace gas and pulverized coal is used for combustion,the peak temperature and the temperature in the roasting zone in the rotary kiln both show a downward trend.That is,the incorporation of gaseous fuel promotes the early start of the combustion process of pulverized coal,significantly shortens the length of the black firehead,and makes the position of the roasting zone closer to the burner,resulting in a stable“club-shaped”appearance of the flame.With the addition of furnace gas fuel,the peak temperature and the temperature in the roasting zone in the rotary kiln both decrease,which helps to alleviate the occurrence of ring formation.The addition of furnace gas fuel can also effectively reduce the NO_(x)emissions.The NO_(x)content at the outlet of the rotary kiln drops from 655 mg/m^(3)to 327 mg/m^(3),and the NO_(x)emissions are reduced by 50.1%.
作者
丁佳文
刘鹏
林书行
杨佳斌
兰孝宇
董启基
马英杰
DING Jiawen;LIU Peng;LIN Shuxing;YANG Jiabin;LAN Xiaoyu;DONG Qiji;MA Yingjie(School of Mechanical and Power Engineering,Shenyang University of Chemical Technology,Shenyang 110142,China)
出处
《煤质技术》
2025年第3期63-68,共6页
Coal Quality Technology
基金
2024级沈阳化工大学国家级大学生创新创业计划训练基金资助项目(202410149016)。
关键词
气固两相燃料
数值模拟
混合燃烧
回转窑
五通道燃烧器
烟气回收
流体动力学方法
燃烧速率
gas-solid two-phase fuel
numerical simulation
mixed combustion
rotary kiln
five-channel burner
flue gas recovery
fluid dynamics method
combustion rate
