油浆蒸汽发生器管板失效分析

前郭石化分公司重油催化裂化装置的蒸汽发生器管板与换热管焊接处及管桥大面积开裂,裂纹大多从管束开始沿平行或垂直于焊缝的方向向管板延伸。通过对管板开裂原因进行的多方面分析,认为管板开裂不是由于材质本身造成的,而是由于改造投入使用初期,频繁的开、停工,造成管板处于热胀冷缩的交变状态,导致管板受到温差交变应力作用即交变热载荷作用而产生疲劳破坏,以及在腐蚀介质(水蒸气、氧、油浆中的硫)及拉应力的共同作用下,又使管板受到应力腐蚀。并提出了相应的改进及预防措施。

REASON ANALYSIS ON TUBE SHEET CRACKING OF SLURRY OIL STEAM GENERATOR AND ITS PROTECTION

The steam generator and heat exchanger in FCCU of Qianguo refinery is cracked on the welds of tube sheet to a large extent after it was commissioned in half a year.A lot of cracks in the tube sheet of oil slurry steam generator were found,and the cracks started from the tube bundles and spread horizontally along with the direction of radius.The reason of the cracking on the CUU tube-plate was analyzed.The experimental result indicates that the cracks is not caused from the material quality,it was just caused by the frequently start-ups and shut-downs during the period of start of run, which brought out the tube and sheet frequent expansion in thermal and contract in cold,thus lead fatigue failure on the welded joint of tube-plate.The existence of water vapor,oxygen and H2S caused stress corrosion cracking.The conclusion is that an interaction between fatigue and stress corrosion is the reason of the cracking on the CCU tube-plate.The improvement solutions of the crack protection are put forward.