炼化设备冲刷腐蚀失效分析及控制策略

目的冲刷腐蚀失效是制约炼油装置安全运行的重大隐患,通过分析炼化设备系统中典型冲刷腐蚀失效的机理和影响因素,提出石油炼制过程中冲刷腐蚀的控制策略。方法基于炼油装置的工艺流程、设备和管道的结构设计、腐蚀介质和材质等,分别针对减压转油线防冲板、硫酸烷基化装置反应流出物注碱口管线、酸性水汽提塔顶富氨气系统,以及焦化分馏塔进料段塔壁腐蚀问题进行失效分析。结果通过将材质升级为317L,避免了减压转油线防冲板因环烷酸冲刷腐蚀而减薄。通过改进碱注入方式和优化操作工艺方式,减缓了硫酸烷基化装置反应流出物注碱口管线的硫酸腐蚀。通过将空冷器管束材质升级为316L,及增加管道直径的措施,防治了酸性水汽提塔顶富氨气系统酸性水冲刷腐蚀。通过更换进料分配器解决了焦化分馏塔进料段塔壁腐蚀泄漏的难题。结论炼化设备冲刷腐蚀的控制策略:依据主动防腐的观念,在遵循炼化设备选材导则进行合理选材的基础上,充分考虑设备、管道的实际工艺操作情况,针对具体部位进行腐蚀评估,发现薄弱部位并及时调整相关操作(操作工艺、工艺防腐和腐蚀监测等),从而保证了炼化装置的安全稳定运行。

Failure Analysis and Controlling Strategy on Erosion-Corrosion of Petrochemical Equipment

The work aims to put forward the strategies to control the erosion and corrosion in the process of petroleum refining by analyzing the mechanism and influence factors of typical corrosion-erosion failures in refining equipment and system as the said failures are main potential troubles to the safe and stable operation of the refining units. Based on technological process of oil refining equipment, structural design of equipment and pipes, corrosive medium and materials, etc., the corrosion failures of impingement baffle in vacuum transfer line, reactor effluent pipeline at injection inlet of sulfuric acid alkylation unit, rich ammonium system in the top of sour water stripping tower, and tower wall in feeding zone of coking fractional column were respectively analyzed. The thinning of impingement baffle in vacuum transfer line eroded and corroded by naphthenic acid corrosion was avoided by the material upgraded to 317L. The sour water corrosion in rich ammonium system in the top of sour water stripping tower was prevented by the material upgraded to 316L and increasing the diameter of pipeline. The corrosion and leakage problem of tower wall in feeding zone of coking fractional column was solved by replacing the feeding distributor. The strategies to control the corrosion-erosion of the refining equipment: based on the concept of active anti-corrosion and selecting material by following the material selection guidelines, the possibility of corrosion in specific region should be evaluated by fully taking into account the actual technological operations of the equipment and pipelines. Once the major corrosion regions are found, relevant operation should be timely adjusted (operation processes, process anti-corrosion and corrosion monitoring, etc.), so as to ensure the safe and stable operation of the refining device.