催化裂化装置柴油系统腐蚀分析

Analysis of Corrosion in Diesel System of FCC unit

陕西延长石油(集团)有限责任公司延安炼油厂现有一套1.0 Mt/a催化裂化装置,主要处理常压渣油。在装置运行过程中,发现分馏塔柴油系统出现了较为严重的腐蚀现象,其中柴油系统工艺管线、冷却设备因腐蚀穿孔多次出现泄露情况,对装置的安全平稳运行带来了严重影响。根据装置的腐蚀情况,分析了装置产生腐蚀的主要原因为H2S,HCl和水的系统环境腐蚀,即H2SHCl-H2O腐蚀体系,一般腐蚀产物中以FeS2和Fe2O3为主,同时存在少量FeCl3等物质,探讨了腐蚀产生的机理,并根据实际生产过程中的经验,用合炼方式、日常检查、采用Ni-P合金或涂高温有机涂层以及停工期间尽量采用碱洗钝化或气相缓蚀剂加充氮保护等,使含硫污水中铁离子明显降低,易腐蚀部位减薄速度降低,装置运行周期变长。

Shaanxi Yanchang Petroleum （Group） Co. , Ltd. operates a 1.0 MM TPY FCC unit mainly to process atmospheric residue. Serious corrosion was found in the diesel system of fractionation tower during the normal operation. Corrosion leaks occurred in the process pipelines and cooling equipment due to corrosion failure, which seriously affected the safe and stable operation of the unit. Based on the corrosion conditions of the unit, the main corrosion culprits were analyzed and determined to be H2S, HCI and water i.e. H2S - HC1 - H20 corrosion system. The main corrosion products were FeS2 and Fe203 with a small amount of FeC13. The corrosion mechanisms were studied. Effective measures were taken such as mixed processing, strengthened routine examination, the application Ni - P alloy or HT organic coatings, caustic washing and addition of gas - phase corrosion inhibitor with nitrogen protection, etc. These have reduced the Fe ions in sour water, lowered the thinning speed of locations subject to corrosion and extended the operating cycle of the unit.