Abstract: The energy utilization status in fluid catalytic cracking (FCC) unit is a crucial factor affecting carbon emissions. Evaluating carbon footprint based on the energy evolution of product materials holds significant scientific value. The coke-burning in the regenerator represents the largest and most concentrated carbon emissions source. Carbon emissions can be allocated based on their energy destinations (the heat carried by flue gas, by catalysts, and steam production). Additionally, considering the heat supply mechanism of catalysts from the regenerator to the reactor, carbon emissions from the reactor are also determined. For the reaction and fractionation processes, carbon footprint could be calculated based on the enthalpy increment of materials and combined with the carbon footprint of raw materials from upstream. It is indicate that the total carbon footprint emissions from the main products of FCC operations amount to 20233.1 kg/h, while steam and heat output amount to 59544.2 kg/h. Among different main products, diesel has the lowest carbon footprint at 13.10 kg/t, while liquefied petroleum gas (LPG) has the highest carbon footprint at 63.69 kg/t. LPG and gasoline have the similar carbon footprints due to their identical processing stages.

Key words: catalytic cracking, carbon footprint, reactor-regenerator system, main fractionator, absorption-stabilization system, emission source inventory