飞灰作用下的SCR系统催化剂磨损特性研究

Study on Erosion Characteristics of SCR System Catalyst with Fly Ash

采用实验与数值模拟结合的方法研究飞灰颗粒与催化剂的磨损问题,利用Lagrange法追踪飞灰颗粒在催化剂近壁区的运动轨迹,并结合催化剂磨损关联式计算催化剂的磨损率。结果表明:在研究工况范围内,催化剂前端磨损率为催化剂孔道磨损率的266~304倍,沿催化剂孔道出口方向,催化剂孔道磨损率在0~30 mm时下降较快, 30 mm之后时下降减缓;受催化剂钢网处飞灰的二次反弹和局部烟气速度高的影响,小飞灰粒径对催化剂前端产生两次撞击角度波峰,钢网边缘波峰处的磨损率较大,导致催化剂变薄,大飞灰粒径惯性大对催化剂前端中部只产生一次撞击角度波峰,引起磨损区域变大;催化剂前端磨损率随烟气速度呈指数增长,随飞灰粒径增大,飞灰粒径对催化剂前端磨损率的影响减弱。

The combination of experiment and numerical simulation method was conducted to study the erosion of plate catalyst by fly ash particle.The trajectory of fly ash particles in the near wall region of the catalyst was tracked by Lagrange method,and the erosion rate was calculated according to the erosion rate correlation formula of catalyst.Results showed that: Within the research conditions,catalyst front erosion rate was 266 to 304 times of catalyst pore erosion rate.In the direction of catalyst pore outlet,erosion rate of catalyst pore decreased rapidly within 30 mm,and slowed down beyond 30 mm.Affected by the secondary rebounded from fly ash particles at the steel mesh of catalyst and high local flue gas velocity,the small size particle generated two impact angle peaks at the front,leading to thin catalyst,while the large size fly ash particle generated only one impact angle peak in the middle of catalyst front,resulting in a large erosion area of catalyst.The erosion rate of catalyst front increased exponentially with the flue gas velocity,as the fly ash particle size increased,while the effect of fly ash particle size on the erosion rate of catalyst front was decreased.