摘要
某炼油厂2011年首次检修时发现高压加氢装置硫化氢汽提塔热低分油进料段11至15层塔盘发生严重腐蚀,大幅超过Mc Conomy曲线相应工况下腐蚀速率0.025 mm/a,而2014年检修时未出现严重腐蚀问题。2011检修时塔盘正面布满腐蚀麻点,背面基本无明显腐蚀迹象,表明腐蚀主要发生在液相,气相腐蚀轻微。通过观察腐蚀形貌,核算塔顶水蒸气分压,判断仅可能在冷回流区域形成液态水点,断定腐蚀不是由于水相腐蚀导致。分析开工以来数据,在2011年前平均负荷为设计负荷的116.34%,最大负荷达到设计负荷的147.6%,而塔底汽提蒸汽量并未调整。分析认为热低分油进塔过程必然部分气化,产生很多微气泡无法及时汽提出液相,在向塔底流动过程中温度逐渐降低,微气泡液化产生汽蚀导致了严重腐蚀。生产实际表明:2011年后塔负荷控制在设计负荷105%以内,调整汽提蒸汽量及时汽提出热低分油进料液相中的各种微气泡,保证塔在设计工况内运行,可避免腐蚀发生。
Serious corrosion was found in the 11 to 15 trays of H2 S stripping tower located in the low boiling point feed section in 2011 maintenance of Huizhou Refining ＆ Chemical Company. The corrosion rate of the tray was 0. 025ram/a, which exceeded the McConomy curve value in the same conditions. However no serious corrosion tendency was found during 2014 overhaul maintenance. Some corrosion pits were distributed in the front of the trays, and no obvious corrosion trace was observed in the reverse side in 2011 maintenance. The result of the corrosion morphology indicated that the corrosion was mainly formed in the liquid phase and slight in the gaseous phase. Based on the corrosion morphology of the tray and partial pressure of water vapor in the tower overhead, the liquid phase was only formed in cold reflux area, and it is concluded that the corrosion pits in the trays were not caused by the liquid phase. The operating data of the unit after start - up were analyzed. The average operating load of the unit before 2011 was 116.34% of design load, the maximum operating load was 147.6 of design load, and flow rate of stripping steam at the bottom of the tower was not adjusted. The analysis results confirm that the hot oil of low boiling point will partially gasify and produce bubbles during the process of entering the tower. The temperature gradually goes down and the bubbles collapse, leading to serious cavitation erosion. The operation practice after 2011 shows that： the tower load should be controlled within the 105% of design load, and the flow rate of stripping steam should be adjusted to timely strip off the micro bubbles from liquid feed to prevent the corrosion.
出处
《石油化工腐蚀与防护》
CAS
2015年第2期46-49,共4页
Corrosion & Protection In Petrochemical Industry
关键词
硫化氢塔
微气泡
汽蚀
负荷
H2S stripping tower, micro bubble, cavitation, load
