碱液冷却器泄漏原因分析与对策

Analysis of causes of Lye cooler leakage and countermeasures

针对中国石油乌鲁木齐石化分公司1.20 Mt/a延迟焦化装置液化石油气脱硫醇系统碱液冷却器的泄漏问题,对碱液性质和冷却器腐蚀特征进行了分析,排除了该冷却器在碱液质量分数为20%,温度为50~55℃的环境中发生＂碱脆腐蚀＂的可能性。结合工艺流程特点和冷却器发生腐蚀的部位,断定该冷却器的腐蚀是由于碱液携带有氧气体积分数高达近20%的尾气,在冷却器中发生电化学吸氧腐蚀所致。通过对该冷却器腐蚀机理的分析,提出了工艺流程改造、牺牲阳极保护、操作优化等改进措施,并且采用了简便的牺牲阳极保护的方法。实践证明对该冷却器的腐蚀泄漏原因分析推断正确,采取的措施可行有效。

Based upon the leaking of lye cooler in the LPG sweetening system of a 1. 2 MM TPY delayed coking unit in Petro China Urumqi Petrochemical Company and the analysis of properties of lye and corrosion characteristics of cooler,the possibility of common caustic embrittlement corrosion at 20 mol% of alkali solution concentration and 50 to 55 ℃ temperature condition is excluded. In consideration of process characteristics and the location of corrosion in the cooler,it is concluded that the corrosion of the cooler is the electrochemical oxygen corrosion because of the oxygen carry-over in the lye which is as high as 20%. Based upon the analysis of mechanisms of corrosion in the cooler,effective corrosion prevention measures are proposed such as revamping of the process,application of sacrificial anode protection and operation optimization,etc..The practices prove that the analysis of the causes of corrosion leaking of the cooler is correct,and the measures taken are very effective.