Failure Mechanism Of Steam Jet Pump And Protection Countermeasures Of Top Of Atmospheric And Vacuum Distillation Tower

Atmospheric and vacuum system is the first process in petrochemical industry.Due to the introduction of heavy crude oil in recent years,corrosion risk of atmospheric and vacuum equipment is increasing,and corrosion occurs more frequently.Corrosion failure of equipment in atmospheric and vacuum systems is a difficult problem in petrochemical industry.Therefore,the research on corrosion failure and protection measures of atmospheric and vacuum system has strong practical value and significance.In this work,traditional test methods such as Scanning Electron Microscope（SEM）,Energy Dispersive Spectroscopy（EDS）and Computational Fluid Dynamics（CFD）simulation are used to study the rapid failure of steam jet pump located at the top of the vacuum distillation tower.The results show that the feed oil of the atmospheric and vacuum system has a high content of sulfur and chlorine,and the traditional corrosion inhibitor injection method cannot make the corrosion inhibitor evenly and fully mix with the top gas in the outlet pipe of the atmospheric and vacuum tower,and the COV at the outlet can be as high as 1.20.This leads to the low absorption efficiency of corrosion inhibitor on the corrosive gas in the tower top gas,which causes the tower top gas to carry acidic gas into the follow-up equipment,and the H₂S-HCl-H₂O corrosion environment is formed in the steam jet pump located on the top of vacuum tower.The steam jet pump suffered from the erosion of high-speed fluid and the corrosion of acidic medium in the process of operation.Under the coupling effect of mechanical erosion and electrochemical corrosion,the wall surface of the pump decreased rapidly,resulting in the leakage of the jet pump three months after it was put into operation.To solve the injection pump and other equipment corrosion problems,this work design tangential-swirl nozzle to inject corrosion inhibitor into the pipeline,so as to improve the absorption efficiency of corrosion inhibitor,and to reduce the equipment in the crude distillation tower cooling system failure risk.The results show that the tangential-swirl nozzle can greatly improve the mixing effect of the corrosion inhibitor and the top gas in the pipeline,and the volume fraction of the corrosion inhibitor in the pipeline can be improved by increasing the injection amount.With the same injection flow rate,the single-inlet nozzle can reduce the pipe outlet COV to 0.51,while the double-inlet nozzle can further reduce it to 0.32.After the study of different traffic models show that the tower cooling system via the tangential-swirl nozzle injection of corrosion inhibitor for oil distillation tower corrosion problem of the cooling system is an effective means of prevention and cure,at the same time,this study also to solve the problem of low temperature corrosion problem of tower cooling system provides a new research idea.