高压汽包炉水冷壁爆管原因分析

通过爆口试件的金相分析、垢样扫描电镜及能谱分析和X射线衍射分析,结合对实际运行状况的调查,确定水冷壁爆管损坏的原因是由于排污不畅和停用腐蚀导致的介质浓缩下的碱腐蚀。针对碱腐蚀的主要原因,提出了相应的处理措施。

ANALYSES OF WATER-WALL TUBE FAILURE FOR A HIGH-PRESSURE DRUM BOILER

The microstructure,crack mode,morphology of the brittle fracture and scale of the damaged water-wall in a high-pressure drum boiler were studied.The composition of the corrosion product was investigated by using X-ray diffraction,scanning microscopy(SEM) and electric energy spectrum as well as chemical analysis.It is believed that the damage of the tubes was caused by hydrogen damage.The superfluous non-captive hydroxyl in boiler water which greatly concentrated under scales and deposits of the tubes due to the bad blowdown system and condenser leakage was the root cause for the damage.Theoretical analysis and investigation on the boiler actual operation and the cycle chemistry supervision confirmed that the main reason of the waterwall tube failure was caustic corrosion.Some improvement measures were put forward.