硫磺装置S-Zorb烟气管线失效分析  

Failure analysis of S-Zorb flue gas pipeline of sulfur recovery unit

作　　者：谈平庆[1] 

机构地区：[1]中国石油化工股份有限公司镇海炼化分公司,浙江宁波315207

出　　处：《石油化工腐蚀与防护》2015年第6期61-64,共4页Corrosion & Protection In Petrochemical Industry

摘　　要：2014年7月在S-Zorb烟气管线投用过程中,管线弯头处出现了严重的泄漏问题,检查发现管道弯头热影响区处出现了开裂。经分析是S-Zorb装置烟气中的硫酸和碳酸气体在管道低于露点温度部位出现了冷凝,对管道造成了非常严重的电化学均匀腐蚀,并且在管道弯头焊缝热影响区等应力较高处出现了连多硫酸应力腐蚀,导致开裂失效。提出并采取预防措施,由于存在大面积的均匀腐蚀,已将整条管线进行更换,并进行焊后热处理,降低管线焊缝热影响区的残余应力,避免发生应力腐蚀;为了防止管道遭受烟气露点腐蚀,应控制烟气温度在露点温度以上,更换为碳钢管线加双伴热结构;烟气管线在停运时,要采用氮气吹扫,避免烟气进入管道内形成凝液,以保证装置的平稳运行。The elbow of A-ZORB flue gas pipeline leaked seriously in the operation in July 2014. The examination found the cracking in the heat affected area of the elbow. The analysis concluded that the leakage was caused by the cracking failure of pipeline because of serious electro-chemical corrosion due to the condensation of sulfuric acid and carbonic acid in S-Zorb units＇ flue gas at the dew point location as well as by polythionic acid stress corrosion at the high stress location in heat affected area of welds. The prevention measures have been taken. The existing pipeline was replaced with the new one because of large areas of uniform corrosion. The welds are heat treated after welding so as to reduce the residue stress at the heat-affected area to prevent stress con＇osion. To prevent the pipeline from dew point corrosion of flue gas, the flue gas temperature should be maintained at that higher than the dew point temperature. The carbon steel pipeline is replaced with heat traced pipeline, After the shutdown of flue gas pipeline, the pipeline should be flushed with nitrogen and flue gas should be prevented from going to pipeline to form condensate so as to ensure the stable operation of the unit.

关 键 词：硫酸 烟气 连多硫酸 腐蚀与防护 

分 类 号：TQ125.11[化学工程—无机化工] TE96[石油与天然气工程—石油机械设备]