催化裂化装置低温热水换热器泄漏原因分析

大连石化分公司1.4 Mt/a重油催化裂化装置共有低温热水换热器14台,在运行中经常出现管束的腐蚀泄漏问题,严重影响了装置低温热水系统的稳定运行。从低温热水系统的氧腐蚀产生机理、孔蚀和酸腐蚀形成的环境、低温热水系统工艺流程设置、系统流速对垢下腐蚀形成的条件等方面分析了低温热水换热器管束泄漏的原因。分析得出:低温热水对管束外壁形成的酸腐蚀、氧腐蚀和孔蚀等是导致管束泄漏的主要原因;由于工艺流程设计本身的缺陷导致流速过低形成垢下腐蚀也是管束泄漏的原因之一。针对上述原因提出了相应的解决措施。

Analysis of Causes of Leaking of LT Hot Water Heat Exchanger

The corrosion leaking of tubes always occurred in the 14 low-temperature（LT） hot water heat exchangers in the 1.4 MM TPY heavy oil FCCU in PetroChina Dalian Petrochemical Company,which seriously affected the stable operation of the LT heat system.The corrosion causes of tubes of LT hot water heat exchangers were analyzed in respect of mechanisms of oxidation corrosion of LT hot water system,the environment of pitting corrosion and acid corrosion,design of LT hot water system and impact of system velocity on the formation of underdeposit corrosion.It is found that the tube leaking was mainly caused by acid corrosion,oxygen corrosion and pitting corrosion on the external wall of tubes by LT hot water.In addition,the underdeposit corrosion from low velocity because of inappropriate design of process flow was also one of the causes of leaking.Corresponding effective countermeasures have been proposed.