污水汽提分凝液冷却器管束泄漏原因分析

介绍了大连石化分公司1.4 Mt/a重油催化裂化装置污水汽提单元一、二级分凝液冷却器的工艺流程及日常运行修理情况,在2012年停工消缺期间发现管束因结盐堵塞并出现大量泄漏现象,冷却器丧失冷却功能,严重影响污水汽提单元的正常运行。针对相关腐蚀情况分析了管束泄漏原因。分析得出:管内壁腐蚀为海水腐蚀,但造成管束泄漏的主要原因是氯化铵在换热管内壁形成垢下腐蚀,管束外壁则由于Cl-和H2S形成的孔蚀和点蚀综合作用导致换热管穿孔泄漏失效。针对上述原因提出了管束材质升级和加强腐蚀监测等解决措施,保证污水汽提单元的运行稳定。

Cause analysis of leaking of condensate cooler tubes in sour water stripper

The process flow and routine maintenance of the I st - stage and 2nd - stage condensate water coolers in the sour water stripper of a 1.4 MM TPY residue fluidized- bed catalytic cracking unit in PetroChina Dalian Petrochemical Company are introduced. In the shutdown for maintenance in 2012, a large amount of leaking spots and plugging by salt deposition were found in the cooler tubes, which greatly reduced the cooling efficiency and affected the normal operation of sour water stripper. The analysis of corrosion causes concluded that the corrosion on the internal water of tubes was sea water corrosion. Whereas, the main cause of tube leaking was the under - deposit corrosion by ammonia chloride on the internal wall of tubes. The corrosion leaking failure of tubes was the result of combination effect of under - deposit corrosion of internal wall and pit corrosion of CI - and H2 S on the external wall of tubes. After effective measures were taken such as material upgrading for tubes and strengthening of corrosion monitoring, stable operation of sour water stripper has been ensured.