摘要
以某电厂600MW机组锅炉的单个DRB-4Z型双调风旋流燃烧器为例,通过CFX软件模拟研究一次风速、外二次风叶片角度对燃烧器出口流场的影响。结果表明:适当减小一次风速可增大回流区,有利于煤粉的着火,但过低的一次风速会使一、二次风的后期混合变弱,不利于煤粉的稳定着火;随外二次风叶片角度的增大,火炬长度明显增大,推迟了外二次风与一次风的混合,降低了着火稳定性,同时易引起燃烧器对面水冷壁的结渣;随外二次风叶片角度的减小,旋流强度增大,煤粉气流的最大轴向速度和最大切向速度的衰减加快;当外二次风叶片角度过小时,较大的旋流强度使火焰尾部形成开放式气流同时在尾部中心出现回流区,将降低燃烧器的使用寿命并对着火稳定性产生不利影响。
The influence of primary air velocity and external overfire air blade angle on outlet flow field was simulated by CFX soft ware,taking the single DRB-4Z dual channel swirl burner of a power plant as an example.Results indicate that,properly reducing the primary air speed can enlarge the recirculation zone,but too low the speed will weaken the later stage mixing of primary and secondary air,which goes against the stable ignition of pulverized coal.With an increase in external secondary air blade angle,the flame length increases significantly,postponing the blending of external secondary air and the primary air,decreasing the ignition stability,and causing slagging on the waterwall opposite the burner.As the outer secondary air blade angle decreases,the swirl strength reduces,and the reduction of the highest axial and tangential velocity of the pulverized coal accelerates.Too small angle of the outer secondary air causes the formation of recirculation zone in the center of flame tail,which has adverse effect on the combustion stability and shortens the service life of the burner.
出处
《热力发电》
CAS
北大核心
2012年第11期36-40,共5页
Thermal Power Generation
关键词
旋流燃烧器
双调风
冷态试验
一次风速
外二次风
叶片角度
回流区
swirl burner
cold test
primary air velocity
out secondary air
blade angle
recirculation zone
numerical simulation
