加氢裂化装置高压换热器管束腐蚀原因分析

CAUSE ANALYSIS ON THE CORROSION OF HIGH-PRESSURE HEAT EXCHANGER TUBES IN HIGH-PRESSURE HYDROCRACKING UNIT

加氢裂化装置用氢主要来源于制氢和重整两个装置,两装置来氢有着各自的特点:制氢装置来氢相对比较干净,重整装置来氢中含有一定量的氯离子。加氢裂化装置大量使用奥氏体不锈钢,在含氯离子的介质中可能会被腐蚀。某加氢裂化装置高压换热器壳程不锈钢换热管表面出现大量的腐蚀坑,根据装置的改造情况、换热管表面腐蚀情况等得出该换热管腐蚀原因为装置改制氢装置来氢为重整装置来氢。重整装置来氢中氯离子含量超标,在一定的条件下腐蚀设备。为了控制腐蚀,可以通过改善脱氯效果、改变工艺、材料升级以及在介质中添加缓释剂等方法。

Hydrogen used in hydrogenation unit is mainly from hydrogen manufacturing unit and catalytic reforming unit.Hydrogen from these two units has different characteristics:hydrogen from hydrogen manufacturing unit is comparatively clean,yet that from catalytic reforming unit contains certain amount of chloridion.Austenitic stainless steel is mostly used in hydrocracking unit and the unit might be corroded in medium with chloride.Much pitting appeared on the surface of the stainless heat exchanger tubes of high-pressure heat exchanger shell pass in certain hydrocracking unit.According to the alteration of the unit and the surface corrosion of the heat exchanger,the paper found out that the corrosion reasons for the heat exchanger tubes was that hydrogen from hydrogen manufacturing unit had been changed to that from catalytic reforming unit which contained chloridion beyond the standard and corroded the equipment under certain condition.In order to control corrosion,some methods can be adopted including improving dechloridizing effect,changing process,upgrading materials and adding slow releasing agent and so forth.