大港电厂3号锅炉再热器管屏超温的数值诊断

采用FLUENT商业软件对大港电厂3号锅炉再热器管屏金属出现的超温问题进行了数值诊断．研究了反切风的投入量及投入方式、炉膛风箱差压的大小、二次风下摆与否等因素对该锅炉燃用设计煤种时，对末级再热器入口（末级过热器出口）截面上的烟气速度分布和温度分布的影响．指出要有效地避免该锅炉再热器管屏出现超温现象，必须采取相应措施重构流场．根据影响流场的主要因素，设计了8个重构工况，几乎所有工况都对基准工况下的流场和温度场有修正作用，而尤以同时采用二次风反切并下摆、增大炉膛风箱差压等手段来重构后的工况，可以更好地修正此处的速度偏差和温度偏差，进而避免再热器管屏的超温．所获结果无疑对该锅炉的稳定、安全运行具有指导作用，同时对该厂的其他锅炉和国内相近容量和结构的锅炉也具有一定的借鉴意义．

Numerical Diagnoses to the Reheater Panel Overheating of No.3 Boiler of Dagang Power Plant

FLUENT was utilized to diagnose numerically the metal overheating issues of the reheater pendants existing in the No.3 boiler of Tianjing Dagang Power Station.Some factors that may affect the velocity and the temperature distributions at the section of the final reheater inlet(final superheater outlet) had been taken into account when the designed coal was burnt,such as the quantity and fashion of counter-flow in operation,the pressure difference in the air box,and downward inclination of secondary air injection.The basic conclusion is that some corresponding measures should be taken to rebuild the flow field constructions in order to effectively avoid the metal overheating of the boiler's reheater pendants.To get more scenery in detail,eight reformation cases were arranged on the main field influencing reasons to retrofit this boiler numerically.Compared to the base case,all the reformation cases had some emendatory effects to the flow and the temperature distributions.The most outstanding one among the reformations was the Case I,where the secondary air(OFA and the upper secondary air of D primary air burner) was countered and inclined,and the pressure difference in the air box was increased.Case I can more efficiently modify the velocity and the temperature deviations in the overheating place to ensure the furnace operate in steady and safety ways.These conclusions are,undoubtedly,valuable to the other units of this station,and also to the other furnaces throughout China with the similar construction and capacity.