Failure analysis and prediction based on corrosion thinning behaviour of atmospheric tower top and volatilization line connection area

Abstract

Dew point corrosion is one of the most common corrosion forms in an atmospheric tower. In this paper, process analysis and numerical simulation were performed to reveal the corrosion phenomenon at the top of atmospheric tower and the volatilization lines in a petrochemical enterprise. Through the analysis of corrosion morphology and corrosion products, it shows that the corrosive area is caused by the dew point corrosion under the H2O-HCl-H2S environment, and the dew point temperature is 97.8 °C. Moreover, the Eulerian Wall Films (EWF) model is established to simulate the formation process of liquid film at the initial stage of dew point condensation. The high-risk area of dew point corrosion is the aggregation position of the liquid phase which is located at the interface at the top of the tower, the inner elbow of the volatilization line, and the lower wall of the horizontal tube of the volatilization line. It is found that low-temperature and low-velocity are two main reasons that cause dew point condensation. The predicted corrosion areas are in line with the actual failure location, which verifies that the CFD simulation can be used to predict the thinning area of the atmospheric tower.