柴油加氢装置低分油换热器腐蚀泄漏分析

Analysis on Corrosion Induced Leakage of Low Oil Heat Exchanger in Diesel Hydrogenation Unit

催焦化柴油加氢装置反应系统E-206低分油换热器管束发生腐蚀泄漏,其腐蚀产物能谱分析、X射线衍射分析结果表明,腐蚀产物主要为FeS,腐蚀类型为湿H_2S腐蚀。从影响管束腐蚀的工艺操作、管束设计及结垢、温度、材质等因素进行了分析,结果表明管束腐蚀泄漏的根本原因是防冲板设计存在缺陷,使低分油流动减缓,H_2S腐蚀介质在此处积聚、浓缩,导致防冲板处管束遭受严重的湿H_2S腐蚀而穿孔泄漏。此外,换热器壳程温度的大幅升高增加了低分油中H_2S腐蚀介质的反应活性,加速了腐蚀的发展。最后,针对该换热器管束的腐蚀原因,提出了改造防冲板结构的防护建议。

An analysis on corrosion induced leakage of low oil heat exchanger in reaction system of hydrogenation unit for coker diesel and catalytic diesel was conducted by means of visual inspection,SEM with EDS and XRD. Results indicated that the corrosion products was ferrous sulfide,and the corrosion type was wet hydrogen sulfide corrosion. The primary cause was that there existed deficiencies in the design of the impingement plate of tube bundle,in this case low oil flowing slowly and hydrogen sulfide gathering, so the tube bundle near the impingement plate was subjected to wet hydrogen sulfide corrosion. Furthermore,with the increasing temperature the reaction activity of hydrogen sulfide of the low oil in heat exchanger increased, thereby the corrosion reaction was accelerated. Finally, the prevention measures were put forward with special emphasis on the improvement of construction for the impingement plate.