Abstract: In a typical refinery, nearly 30%-50% of carbon dioxide (CO₂) is emitted from the regenerator of fluid catalytic cracking (FCC). As the main source of CO₂, The regenerated flue gas has the characteristics of large volume flow rate and low CO₂ concentration, this results in high operating cost of the traditional post-combustion carbon capture technology. In order to capture CO₂ with high efficiency and low cost, an in-situ enrichment process of CO₂ in regenerator was proposed in this work. Computational fluid dynamics and process simulation were used to explore the feasibility of the new process and the potential impact of the new process on the existing equipment. The results showed that the new process could ensure the normal fluidization of gas-solid flow field in the regenerator. The volume fraction of CO₂ in flue gas and dry flue gas exceeded 85% and 93%, respectively. The change of component concentration of regenerated flue gas had little influence on the following key equipment, such as waste heat boiler, flue gas turbine, coal economizer, desulfurization and denitrification tower, etc., so there was no need to replace the existing equipment. This work will provide a new process idea for CO₂ enrichment and capture of regenerated flue gas.

Key words: fluid catalytic cracking, regenerator, carbon dioxide, in-situ enrichment