同心反切燃烧锅炉四角配风不均对炉内多相流动的影响

四角切圆燃烧锅炉中各角一、二次风风速均衡是提高锅炉燃烧效率 ,防止炉内火焰中心偏移、炉膛结渣的重要因素。但大容量锅炉多采用直吹式制粉系统 ,且送粉管道阻力不均 ,燃烧器数量众多 ,易发生配风不均。采用数值模拟方法对采用同心反切二次风系统的某 3 0 0MW四角切圆燃烧锅炉四角配风不均对炉内多相流动特性进行了多工况模拟。获得了配风不均对炉内切圆中心、颗粒运动轨迹、贴壁风速等的影响。同时就配风不均对采用同心反切二次风系统和不采用二次风反切技术的四角燃烧系统的影响进行了比较 ,结果表明 ,采用同心反切系统的四角燃烧锅炉对配风偏差更为敏感 ,应引起设计和运行人员的注意

Numerical Simulation of the Effect of Corner Air Flow Unbalance on the Concentric Firing System Performance

The uniform distribution of the primary and secondary air flow is an important factor on the concentric firing system performance, resulting in the center flame core, slag prevention and high combustion efficiency. But the wide use of direct fining system, the unbalance between the pulverized coal piping and the big numbers of the nozzles lead to the unbalance between the corner air flow distribution in tangential boilers. In this work, the computational fluid dynamics (CFD) method is employed to simulate the effect of corner air flow distribution on the concentric firing system performance, the center of the tangentially circle, the trajectory of the coal particle are calculated under various operating conditions. The results agree well with the field data. A comparison of the effect of corner air flow unbalance on the furnace aerodynamics and particle trajectory in concentric firing system and standard firing system was carried out, it shows that the concentric firing system is much more sensitive to the corner air flow unbalance.