Optimize Steam Injection Location in Refinery Vacuum Heater Can Reduce Coke Formation

Many refinery vacuum furnaces have problems in coking, even at mild operating conditions. Generally, rapid coke formation is caused by the combination of high peak oil film temperature, long oil residence time and consequent oil instability. The first two factors can be minimized by the design, such as the proper radiant coil size, appropriate tube layout. They can also be reduced by controlling the burner performance and by using coil steam injection. Steam injection can improve the flow pattern, increase oil vaporization and reduce oil residence time. In this paper, Petro-SIM was used to optimize the coil steam injection location to prevent the rapid coke formation in refinery vacuum furnace. The study based on an operating vacuum furnace which was installed recently in a refining plant in China and the model was calibrated using the onsite operating data. Three steam injection locations were studied: the radiant section inlet, one tube ahead of the first flared tube and at the first flared tube.