苯乙烯装置脱氢尾气系统二氧化碳腐蚀与防护

苯乙烯装置脱氢尾气系统的腐蚀主要集中在脱氢尾气后冷却器的进口管道、壳体封头及出口凝液线等部位，具有坑蚀、沟槽状腐蚀及台地状腐蚀等典型的二氧化碳局部腐蚀形貌，其腐蚀机理为金属表面各区域FeCO3腐蚀产物膜覆盖度不同而形成的电偶腐蚀。脱氢尾气系统的设备及管道应用实践表明，脱氢尾气系统的二氧化碳腐蚀环境对奥氏体不锈钢设备及管道腐蚀轻微，而对碳钢设备及管道则腐蚀严重。系统工艺、温度、材质及管道结构等影响因素为二氧化碳腐蚀的发生及发展提供了环境条件和促进作用。针对该系统的工艺流程及腐蚀环境，提出了采取更换材质和加注中和型缓蚀剂相结合的解决方案，取得良好防腐效果。

CARBON DIOXIDE CORROSION OF DEHYDROGENATION EXHAUST OF STYRENE UNIT AND MEASURES

Corrosion of dehydrogenation exhaust system was mainly concentrated in inlet pipes of cooler, casing head and outlet of cooler in styrene unit, with typical local corrosion morphology by CO2, such as pit corrosion, trench corrosion and platform corrosion. The corrosion mechanism was the galvanic corrosion caused by the different coverage of FeCO3 corrosion products on the metal surface. The operation results showed that the corrosion of CO2 was slight toward austenitic stainless steel equipment and pipeline, but serious for carbon steel equipment and pipeline and that the system process, temperature, material and pipeline structure provide the environment condition and promotion for the occurrence and development of carbon dioxide corrosion. In view of the process flow and corrosive environment of the system, the solutions of replacing the material and adding neutralizing corrosion inhibitor was put forward and the good results of anti-corrosion achieved.