Catalyst regeneration fast fluidization

Fig. 1. A 1 MMTA fluid catalytic cracking unit with fast fluidized bed regenerator (courtesy Gaoqiao Petrochemical Company). 1, regenerator 2, first-stage FFB regenerator 3, second-stage FFB regenerator, 4, main fractionator, 5. FFB catalyst cooler 6, catalyst hoppers 7, cyclone...

The FFB regenerator shown in Fig. 7a is used as the basic regeneration reactor. Coke-laden spent catalyst and recirculated regenerated catalyst enter the bottom of the FFB vessel and are fluidized by the combustion air in the operating regime of fast fluidization. The near regenerated catalyst flows cocurrently with the flue gas out from the top of the FFB vessel. After gas/solid separation, the catalyst falls into the bottom of a disengager situated on top of the FFB vessel and maintained in a mildly fluidized state by air... 

Model I Side-by-side configuration Fast fluidized upflow riser regenerator Low pressure High elevation external cyclones Catalyst coolers Full feed pre-vaporization... 

Chen J, Cao H, Liu T. Catalyst regeneration in fluid catalytic cracking. In Kwauk M, ed. Fast Fluidization. Adv Chem Eng 20 389 19, 1994. 

In the riser cracker, the feed oil is sprayed into the fast upflowing stream of regenerated catalyst. The cracking reaction occurs entirely in this nearly plug flow riser, and the selectivity of desired hydrocarbon fractions is thereby markedly improved. Catalyst circulates smoothly between the regenerator and the riser reactor. The regenerator can be an ordinary fluidized bed or a combination of risers with ordinary fluidized beds. 

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