Crude Unit Overhead Systems: Process Configurations to Mitigate Fouling

In the crude distillation column up to 40% of the total heat removal may be in the tower overhead condenser. The quantity of duty available makes heat integration between the column overhead and the unit feed tempting. Approximately 70% of the current crude units recover some portion of this duty. However, many of these units suffer from persistent and serious corrosion problems in the overhead system. In extreme cases, the viability of the entire refinery site may be in doubt due to fouling and corrosion problems. Up to 50% of the refinery’s entire corrosion expense may occur in the crude unit. The root of the fouling and corrosion often lie in basic unit configuration choices. Once the unit configuration is set, anti-fouling chemical addition and unit operating condition limits, while helpful, may never truly solve the unit operating problems. An overview of major factors and a case study of modifications for a specific unit are presented.