连续重整装置预加氢系统腐蚀及防护

Corrosion in Pre-hydrotreating System of Continuous Catalytic Reforming Unit and Prevention

连续重整装置预加氢反应产物分离罐铁离子质量浓度年平均达15.36 mg/L,结晶后的铵盐中,氯离子质量分数达128.27 mg/g,预加氢系统中换热器和后冷器存在严重的氯化铵结晶盐堵塞及垢下腐蚀问题。针对腐蚀现状进行了调研并探讨了腐蚀成因、机理,指出了腐蚀主要由氯引起,而硫对氯腐蚀又起到了促进作用。在预加氢反应器后部,增加两台串联或者并联的脱氯器,利用脱氯剂的吸附原理去除引起腐蚀的硫和氯等元素;在预加氢部位加注缓蚀剂,利用缓蚀剂在金属表面的成膜原理,对设备进行防腐蚀;加强监测管理、材质升级和水洗工作,达到防腐蚀的目的。

In the pre - hydrtreating system of continuous catalytic reforming unit, the yearly average iron ions in the reaction product separator is as high as 15.36 mg/g. In the crystallized ammonium salt, the chlorine ions is as high as 128.27 mg/g. Therefore, serious crystallized salt plugging and under - deposit corrosion are present the heat exchanger and after cooler of the hydrotreating system. The corrosion status is investigated, and the causes and mechanisms of corrosion are studied. It is pointed out that the corrosion is mainly caused by chlorine, which is intensified by sulfur. Two chlorine removers are installed in series or in parallel downstream of hydrotreating reactor to remove sulfur and chloride impurities by chloride removal agent. In addition, corrosion inhibitor is injected in hydrotreating system to prevent corrosion by forming membrane on metal surface. The corrosion is effectively controlled by corrosion prevention of equipment, material upgrading and water washing.