四墙切圆锅炉水冷壁颗粒冲击特性数值模拟

Numerical simulation on the particle impact characteristics to the water wall of a boiler with four-wall tangentially firing

摘要:

为深入了解水冷壁壁面的颗粒冲击特性,使用AnsysFluent对660 MW超临界锅炉的燃烧过程进行数值模拟,通过Fluent内冲蚀磨损模型得出燃烧器区域壁面的颗粒质量冲击量；利用Fluent软件的Sample功能输出壁面颗粒数据,将点数据导入Excel处理,得到冲击燃烧器区壁面的颗粒最高速度及颗粒速度值的分布情况. 结果表明:燃烧器喷口对侧区域的壁面冲击量最大值为6 kg·m^-2·s,冲击燃烧器区壁面的颗粒最高速度可超过30 m·s^-1,其占比不足冲击总颗粒量的0.3%,20~25 m·s^-1的冲击颗粒占比接近10%,颗粒速度的主体为5 ~ 20 m·s^-1. 壁面颗粒冲击量及颗粒速度模拟结果表明,在后墙第二组燃烧器壁面存在着6 kg·m^-2·s的高颗粒冲击量及25 ~ 29 m·s^-1的高颗粒冲击速度同时作用的区域,易发生严重磨损.

Abstract:

To get the particle impact characteristics of the water wall, numerical simulations on a 660 MW supercritical tangentially coal-fired boiler were performed based on Ansys Fluent. The impact mass flow value on the water wall in burner area was gotten by using Fluent erosion wear model. By using the Sample function of Fluent and Excel data processing function, how much the maximum velocity and how the velocity of particles distributes were obtained. The result indicates that the maximum mass flow value of particle impacting contralateral water wall area of burner nozzle is 6 kg·m^-2·s, the maximum velocity of particles impacting the water wall in burner area can exceed 30 m·s^-1 at a rate of 3%, the subject of velocity value is 5 ~ 20 m·s^-1, and particles with a speed from 20 m·s^-1 to 25 m·s^-1 may accounts for 10% of the total. It also shows that the 6 kg·m^-2·s high impact mass flow value and the 25 ~ 29 m·s^-1 high impact velocity coexists on the back wall in the second burner group area, where severe erosion wear may occur.