Catalytic cracking fast fluidization

This type of reactor aims to challenge fast fluidization with its 1 to 10 second gas residence time as the prime reactor for the catalytic cracking of petroleum. The claim is that the higher cracking temperature and shorter residence time will give a very different—and better—distribution of reaction products. 

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...

Fluidized bed catalytic cracking (FCC) Riser reactor fast-fluidized bed regime... 

Table 10.2. Comparison of typical operating conditions for the two principal applications of fast fluidization fluid catalytic cracking and circulating fluidized bed combustion [56, 67].

Next, reactors may be designed to accommodate rapid deactivation-regeneration cycles. The best example is catalytic cracking where coke deposition is so fast that decay takes only minutes. Since, in this case, the feed is the precursor to coke, treatment or guard chambers are not practical. The only solution is to use fluidized beds, which provide reaction and regeneration in a continuous cycle. Other cases are slurry and moving bed reactors, w hen deactivation is not so rapid. 

At very high velocities, all particles fed to the reactor are carried up with the gas, and this mode of operation is sometimes called fast fluidization. However, since there is no definite bed level, a better term for this system is a transport-line reactor or, as it is called in catalytic cracking, a riser reactor. These are discussed in Chapter 10, on novel types of reactors. 

Hot disputes exist as to whether the fine-grid TFM simulation is feasible to capture CFB flow behavior (Benyahia, 2012 Hong et al, 2015 Lu et al, 2009 Syamlal and Pannala, 2011 Wang et al, 2010). For the so-called fast fluidization with Geldart A particles, say, fluid catalytic cracking (FCC) catalyst, Lu et al (2009) pointed out that the fine-grid simulation may improve... 

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. 

Zhang, H., et al., 2009. Catalytic fast pyrolysis of biomass in a fluidized bed with fresh and spent fluidized catalytic cracking (FCC) catalysts. Energy Fuels 23 (12), 6199—6206. 

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