锅炉吹灰孔水冷壁管开裂原因分析

Cause Analysis of Cracking of Boiler Soot Blowing Hole Water Wall Pipe

某热电机组锅炉吹灰孔处SA-210C水冷壁管发生开裂泄露,通过维氏硬度、金相分析、扫描电镜形貌与能谱分析等方法进行了原因分析。结果表明,水冷壁管吹灰位置的封板割缝根部结构尖锐,锅炉启停及负荷瞬时波动造成了水冷壁管及封板局部温度差异较大,产生循环热应力,导致水冷壁管的封板割缝根部的尖锐位置在热应力作用下发生开裂,形成启裂源,并在循环热应力的作用下发生疲劳开裂,造成水冷壁管开裂泄漏。

The SA-210C water-cooled wall pipe at the soot blowing hole of a thermal power unit boiler cracked and leaked.The cause was investigated by the methods such as Vickers hardness,Metallographic analysis,Scanning electron microscopy morphology,and Energy spectrum analysis.The results showed that the root structure of the sealing plate slit at the soot blowing position of the water-cooled wall tube is sharp,and the boiler instantaneous load fluctuations caused significant temperature differences between the water-cooled wall tube and the sealing plate,resulted in cyclic thermal stress.These cause the sharp position at the root of the sealing plate slit of the water-cooled wall tube cracked under the action of thermal stress,formed the crack source,and fatigue cracking under the action of cyclic thermal stress,leading to the cracking and leakage of the water-cooled wall tube.