Studies On Corrosion Mechanism And Anti-corrosion Methods In The First Atmospheric And Vacuum Distillation Unit Of Karamay Petrochemical Company

Corrosion in the first atmospheric and vacuum distillation unit is a key factor relatedwith safe production in Petrochina Karamay Petrochemical Company. It is significant tofind a solution to corrosion in distillation unit. This article through technical research oncorrosion in the first atmospheric and vacuum distillation unit processing viscous crude,found out key factors which can affect safety and reliability of viscous crude oilprocessing unit, analyzed corrosion mechanism, pointed out main corrosive points ofatmospheric and vacuum distillation unit, evaluated the effect of adopted anti-corrosionmethods and provided reliable technical service to ensure "three-year repair cycle".The research on corrosion mechanism shows that in processing viscous crude oil,corrosion in atmospheric distillation unit is mainly produced by HCl-H₂S-O₂-H₂O inlow-temperature part. Meanwhile, it shouldn't be neglected of combined influence madeby high-temperature sulphur corrosion and naphthenic acid. Acid value of crude oil,temperature, velocity of flow and flow state, sulfur content and metal material have maineffect on naphthenic acid corrosion in vacuum distillation tower unit. Among themsynergefic effect made by high-temperature naphthenic acid corrosion and mechanicalerosion corrosion are the main influence factors which can lead to the failure of vacuumdistillation tower unit, especially the heating coil and transfer lines.After many lab experiments and tests on site, different corrosion rate at differentworking conditions and various anti-corrosion methods was evaluated on differentmaterials. Meanwhile, a lot of anti-corrosion methods was proposed and applied.Since implementing various effective anti-corrosion methods to viscous crude oilprocessing, the first atmospheric and vacuum distillation unit in Petrochina KaramayPetrochemical Company, there is no corrosion accident in the past three years. Comparedwith initially one shutdown for 1-2 month, the anti-corrosion effects are obvious. With the development of anti-corrosion methods on the atmospheric and vacuumdistillation unit, each equipment and whole device can now running safer and morereliable.