加工沿海高酸原油减压塔腐蚀原因分析及对策

Cause Analysis and Countermeasures for Corrosion of Vacuum Tower for Processing Coastal High-Acid Crude Oil

加工沿海高酸原油的某石化企业减压塔整体更新运行1 a,检修检查高温部位出现一系列腐蚀问题:第七段及第八段整层填料失去金属光泽,一侧填料大量塌陷、填料腐蚀缺失;第七段集液分配器升气孔V型挡板、集液槽多处腐蚀缺失;集油箱浮球腐蚀缺失一半;以上部位塔内壁、焊道大面积腐蚀。分析认为:加工介质为海洋高酸原油腐蚀性强;为节省设备投资,加工负荷提升,减压塔利用原有的混凝土基础,新设备塔径不能改变,塔高增加,介质线速度提高;填料原材料选用存在问题,加工过程中敏化;制造质量问题,塔内进料分布器安装不居中,进料分配不均;操作负荷时常大幅调整;采油助剂影响等是出现严重腐蚀的重要原因。通过采用优质原材料加工填料,填料、浮球材质升级加厚,平稳生产操作,腐蚀严重部位塔内加注高温缓蚀剂等一系列措施,缓解了高温段填料、塔壁等内构件腐蚀,确保了装置安全运行。

The vacuum tower of a petrochemical enterprise which processes high acid crude oil in the coastal area was recondtructed as a whole after one years operation,and a series of corrosion problems was found in the high temperature parts during maintenance and inspection:the metal luster of the whole layer of packing in the 7 th^8 th stage was lost,packing collapsed and lost heavily in one side due to corrosion,many corrosion defects in the V-shaped baffle of the air-rising hole and the collecting tank of the liquid distributor in the 7 th stage,half of the floating ball corroded in oil collecting boxes in the 7 th stage and half lost,and a lot of corrosion in the inner wall and the welding lines of the towers above.The results showed that considering the highly acidy crude oil of processing medium with strong corrosion,it was intended to save the investment of facilities and to increase of processing capability,and keep the base of old equipment and the diameter of tower unchanged,and the height of towers and the linear velocity of medium was increased.It was found that there was some problems,such as selection of packing materials and sensitization during processing,the manufacture quality of packing materials,the uneven centralization of feeding distributor,the large adjustment of operation load and the influence of additives in oils,which were all the cause of heavy corrosion occured.By adopting a series of measures,such as using high-quality processing packing from manufacturers,upgrading and thickening the material of packing and floating ball,stablizing production operation,adding high-temperature corrosion inhibitors in the towers where corrosion occured seriously,etc.to reduce the corrosion of inner components such as packing and tower wall in high-temperature sections and to ensure the safe operation of the device.