基于Fluent的流化床锅炉床下点火风道流场数值模拟与分析

Numerical simulation and analysis of flow field in fluidized bed boiler underbed ignition duct based on Fluent

某热电厂260 t/h循环流化床锅炉床下点火燃烧器存在稳燃困难问题,在点火风门关至5%,助燃风门保持100%,可点火成功,但点火风道振动较大。将点火风门逐渐开大,导致燃烧器灭火。且左右侧燃烧器燃烧状态不一致,为分析其原因,采用计算流体力学分析软件Fluent对锅炉床下燃烧器风道流场进行数值模拟。结果表明左右侧配风不均匀,同时点火风道内紊流较大,最后通过调整点火风门及助燃风门开度,实现燃烧器稳燃,实际操作思路与数值模拟分析结果一致。建议点火风道设计时合理分配通风风道,避免紊流过大;同时建议用户采购燃烧器设备时,充分与设计人员沟通,了解其设计思路,使各设备相匹配。

The ignition burner under the bed of a 260 t/h circulating fluidized bed boiler in a thermal power plant is difficult to stabilize the combustion.When the ignition damper is closed to 5%and the combustion damper is kept 100%,the ignition can be successful,but the vibration of the ignition duct is large.Gradually opening the ignition damper will cause the burner to extinguish the fire.The combustion state of the left and right burners is inconsistent.In order to analyze the cause,the computational fluid dynamics analysis software Fluent was used to numerically simulate the flow field of the air duct of the burners under the boiler bed.The results show that the air distribution on the left and right sides is uneven,and the turbulence in the ignition duct is large.Finally,the combustion stability of the burner can be achieved by adjusting the opening of the ignition damper and the combustion damper.The actual operation idea is consistent with the numerical simulation analysis results.It is suggested to allocate ventilation ducts reasonably during the design of ignition duct to avoid excessive turbulence.At the same time,it is recommended that users purchase burner equipment,fully communicate with the designer,understand its design ideas,so that each equipment matches.