催化裂化装置顶循油低温热水换热器泄漏分析

Analysis of Leakages of Low- temperature Hot Water Heat Exchanger for Overhead Recycle Oil of FCCU

某石化公司催化裂化装置低温热水换热器在运行中存在管束腐蚀泄漏问题,管束内壁防腐蚀层脱落,涡流检测发现存在均匀腐蚀和严重坑蚀,坑深达1.0mm,壁厚损失大于40%,单程堵管率达到30%。分析认为新水及酸性油类物质造成管束内壁、管板的腐蚀和结垢:硫化物造成了管束外壁的坑蚀;间歇性使用加速了腐蚀的恶化;潮湿的水汽环境造成了氧腐蚀加剧;防腐蚀层脱落失去了有效保护。针对泄漏原因提出了改善低温热水水质、顶循环油中注入脱硫助剂和停用时注入气体缓蚀剂等相应的解决措施。

Corrosion leaking problems occurred in the tube bundle of low - temperature hot water heat exchangers in the FCCU of a petrochemical company. The corrosion protection layer on the internal wall of tubes spalled. Eddy current testing revealed the presence of uniform corrosion and severe pitting corrosion. The pit was 1.0mm deep and the wall thickness loss was greater than 40% , and one - way plugging rate reached 30%. Analysis concluded that the fresh water and acidic oil substances caused corrosion and fouling of tube＇ s internal wall and tube sheet ; Sulfides led to pitting corrosion of tube＇ s external wall ; Intermittent operation accelerated the deterioration of corrosion; Wet steam environment aggravated oxygen corrosion; Anticorrosion layer＇ s spalling off resulted in the loss of effective protection. Corresponding solutions have been proposed such as improvement of low - temperature hot water quality, injection of desulfurization additives into overhead recycle oil and injection of gas corrosion inhibitor when low -temperature hot water supply is shutdown, etc.