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Identifying the Root Cause of Afterburn in Fluidized Catalytic Crackers

The FCC unit has a long history of upgrading low valued feed stocks into much higher valued LPG olefins and motor fuels. One notable reason for the long term success of this technology has been its stability in spite of high catalyst circulation rates. One common exception to this rule is the presence of afterburn which continues to plague many FCC units

This paper provides an overview of how afterburn presents itself in various operations describing both the stable and unstable forms of general or localized afterburn. Several techniques for identification of the likely cause are discussed. Guidelines for the application of the CPFD technology for troubleshooting afterburn are presented. Several examples, including a commercial study where the simulation has accurately identified the root cause of afterburn in an operating FCC unit, are highlighted.

This work was originally presented at the 2016 AFPM Annual Meeting.