Research Of HCl-H₂O Dew-point Corrosion Law At The Low Temperature Part Of Atmospheric Tower Overhead System

Atmospheric distillation is the leading equipment in the refining industry,which smooth operation has influence on the normal operation of the entire process.In recent years,along of the poor quality of crude oil getting more and more serious,the low temperature dew point corrosion at tower overhead system of atmospheric distillation becomes more prominent.Among them,HCl-H₂O dew point corrosion caused by HCl is one of the most typical and most serious failure modes.However,there are few reports about it.Therefore,it is urgent to study the HCl-H₂O dew point corrosion at the low temperature part of atmospheric tower overhead system in order to improve the running reliability of the system.In this paper,the HCl-H₂O dew point corrosion failure at the low temperature part of atmospheric tower overhead system was taking as the research object.By mean of using the method of process correlation analysis and experimental study,the environment and the key influential factors of dew point corrosion were clarified;The quantitative prediction of dew point corrosion was realized;And the dew point corrosion law under different conditions were obtained.The mainly conclusions of this paper as follows:（1）The dew point corrosion environment and its main influencing factors was confirmed combined with the process.It is mainly determined that the main corrosion sources of atmospheric tower overhead system are HCl,H₂S and NH₃;The main factors affecting the dew point corrosion are the pH value of the caustic medium,the temperature and the corrosion protection film,and so on.（2）The prediction of dew point temperature and dew point corrosion position in heat exchanger was realized and the mechanism of dew point corrosion was revealed by the simulation and calculation of dew point corrosion based on Aspen.It is confirmed that the dew point temperature is 121℃when the water content of atmospheric tower overhead oil and gas is 0.2%in the operating temperature range of the heat exchanger;The dew point corrosion of the atmospheric tower system belongs to the HCl-H₂O dew point corrosion;The dew point corrosion mainly occurs after the4850mm distance from the outlet of the heat exchanger.（3）Designing and constructing the HCl-H₂O dew point corrosion experiment device and carry out experiment study.The effect of temperature（80℃¹00℃）and HCl concentration（0mol/L⁰.03mol/L）on HCl-H₂O dew point corrosion law of two typical materials were studied.The innovations of this paper are as follows:In view of the HCl-H₂O dew point corrosion failure at the low temperature part of atmospheric tower overhead system,the process simulation calculation model was constructed by analyzing the cases,and the prediction of the dew point temperature and the dew point corrosion position was realized.The self-designed experimental setup was used to carry out the experimental study,and the dew point corrosion law under complex and variable working conditions was obtained.The results can provide basis for solving the dew point corrosion failure and prolonging the service life of atmospheric tower overhead system.