烟气废热锅炉腐蚀泄漏分析及防护处理

摘要

分析了二催化装置烟气能量回收系统废热锅炉管束腐蚀泄漏的原因.现场腐蚀调查结果表明,废热锅炉的腐蚀主要集中在烟气侧第一排换热管的水平段,特别是折流墙附近换热管束腐蚀最为严重.废热锅炉烟气侧的腐蚀机理为硫酸露点腐蚀,受炉墙砌筑稀料和烟气侧积水的影响,折流墙处换热管束表面温度低于硫酸露点温度,烟气中的SO 3与水蒸气相结合形成硫酸蒸汽在该部位换热管表面凝结,形成硫酸露点腐蚀导致管束穿孔泄漏.最后,针对废热锅炉的腐蚀原因,提出了废热锅炉折流墙结构改造、投用前烘炉、按设计要求施工等消除烟气中硫酸露点腐蚀的防护措施.%The corrosion leakage cause of waste heat boiler tube bundle forflue gas energy recovery system was analyzed in II FCC unit.Field survey results show that the corrosion of waste heat boiler mainly concentrated in theflue gas side of thefirst row in the level of the heat pipe section, especially the corrosion of heat exchange tube bundle is most serious near the baffle wall. And the corrosion mechanism of waste heat boiler for flue gas side was sulfuric acid dew point corrosion, under the influence of the furnace wall thinner and water offlue gas side,surface temperature of heat exchange tube bundle was lower than the sulfuric acid dew point temperature. SoSO3 and steam formed sulfuric acid vapor, and led to a bundle perforation leakage. Finally, in view of the waste heat boiler corrosion reasons, some protection measures were put forward,such as baffle wall structure transformation, oven before use,and constructing according to the design requirements.