300MW电站锅炉包墙过热器管泄漏分析

Leakage Analysis of Wall Superheater Tube For 300MW Power Station Boiler

对发生泄漏的锅炉尾部烟道侧墙的包墙过热器管进行了宏观检查、金相组织检验和硬度检查。结果表明:漏点附件过热器管的组织、硬度正常,导致泄漏的裂纹起源于鳍片。泄漏的直接原因在于吹灰时吹灰器枪管内冷凝水被吹出并附着在正下方的过热器管鳍片上,使鳍片产生交变温差应力,在应力作用下产生裂纹并扩展延伸到过热器管上,导致过热器管发生泄漏。选用合适的吹灰器类型,控制好吹灰器喷口至过热器管表面的安装尺寸并加强吹灰器的安全维护是避免此类问题的关键。分析结果对火力发电厂电站锅炉的安全运行具有重要的指导意义。

The macroscopic examination, metallographic examination and hardness inspection were carried out for the wall superheater tube at the flue of the boiler tail where the leakage occurs. The results show that the structure and hardness of the superheater tube in the leakage attachment is normal, and the leakage crack originates from the fin. The direct cause of the leakage is that the condensate in the nozzle of the ash blower is blown out and attached to the fin of the superheater tube directly below. The fin generates alternating temperature differential stress. Under stress, the fin generates crack, and then the crack extends over the superheater tube to make the superheater tube leak. The key to avoid such problems is to choose the suitable type of ash blower, control the installation size of the ash blower nozzle to the surface of the superheater pipe and strengthen the safety maintenance of the ash blower. The analysis results of the paper are of great significance to the safe operation of boilers in coal-fired power plants.