乙烯裂解炉翅片管腐蚀失效原因

Analysis of Corrosion Failure of Finned Tubes in Ethylene Cracking Furnace

某公司烯烃裂解炉进行投料开车时,发现裂解炉预热段有泄漏现象。通过排查,发现最后一排第一根翅片管有两处穿孔。对翅片管腐蚀穿孔的原因进行了分析,指出原料油中的硫是造成翅片管均匀腐蚀的主要原因。由于对流段炉管为水平安装,在裂解炉停工蒸汽吹扫过程中,残留的蒸汽冷凝成水汇集在炉管下部或凹陷处,进入炉内空气中的氧溶解在其中,从而形成了氧的腐蚀环境,使炉管因腐蚀形成的FeS保护膜遭到破坏,最终导致炉管下部穿孔。

The leaking occurred in the preheating section of ethylene cracking furnace during the start - up of an ethylene cracker. The close examination found two failures in the first finned tube of the last row. The analysis of the failure causes of finned tubes has found that the sulfur in feedstock was the culprit of uniform corrosion of finned tubes. As the tubes in convection section was in horizontal installation, residue steam condensate in steam purging operation accumulated in the lower pocket. With the oxygen in the air dissolved in the condensate, an oxygen - corrosion environment was formed and FeS protection film was damaged, resulting in tube failures at the lower part of the tubes.