重油催化裂化分馏塔顶循氯化铵的腐蚀控制措施及效果分析

Corrosion Control Measures and Effect Analysis of Top Circulation System of RFCC Fractionator

随着炼油厂中原油多元化、重质化程度加深,催化裂化装置原料中氯含量及氮含量均大幅升高,在反应过程中会生成氯化氢与氨,在两者分压足够高的情况下,在分馏塔顶部低温区会出现氯化铵结晶析出,引起催化裂化装置分馏塔上部及顶循环系统腐蚀问题。某石化公司两套催化裂化装置均出现了顶循系统的腐蚀问题,造成了管线和设备的穿孔泄漏以及分馏塔顶循段结盐,对装置的安全生产及产品质量控制造成了极大的隐患和难度。通过采取工艺防腐控制为主、设备材质升级为辅的控制措施,计算分馏塔内氯化铵结盐温度,提高分馏塔顶局部操作温度,对分馏塔顶塔盘进行材质升级处理,分馏塔顶循系统氯化铵的腐蚀问题得到了有效的控制和解决。进一步可采取的优化措施为:增设顶循切水除盐设施,强化源头腐蚀介质控制,统筹考虑提高催化裂化装置稳定汽油终馏点。

Along with the increasingly diversified and heavier crude oils in refineries,the chloride content and nitrogen content in the raw materials to FCC unit increased significantly,which will produce hydrogen chloride and ammonia during reactions.When the partial pressure of hydrogen chloride and ammonia is high enough,ammonium chloride will crystallize in the low temperature zone at the top of fractionator,causing corrosion problem in the upper part and top circulation system of the FCC fractionator.The top circulation systems of two FCC units at a petrochemical company has corrosion problems,which resulted in the perforation and leakage of pipelines and equipment and the salt formation in the top circulation section of fractionator,causing great hidden dangers to the safe production of unit and bringing great difficulties to the product quality control.The ammonium chloride corrosion of the top circulation system of fractionator was effectively controlled and solved by means of calculating the crystallization temperature of ammonium chloride in fractionator,raising the local operating temperature at the top of fractionator and upgrading the material of the tray at the top of fractionator.Further optimization measures to be taken include adding desalination facilities for top circulating cut water,strengthening the control of corrosive media from sources,and giving overall consideration to raising the final boiling point of stabilized gasoline in FCC unit.