Fluid catalytic cracking commercial regenerators

A significant application of FF on a commercial scale is the FF regenerator in fluid catalytic cracking processes. In Chapter 9, J. Chen, H. Cao, and T. Liu of Luoyang Petrochemical Engineering Corporation (LPEC) describe the development and design of four types of FF regenerators and the results of their commercial operation. More than 30 such units are in operation in China. 

Krishna, A.S. and Parkin, E.S., 1985, Modeling the Regenerator in Commercial Fluid Catalytic Cracking Units, Chem. Eng. Prog., 81(4), 57-62. 

Fluid catalytic cracking is one of the key processes for the production of gasoline and diesel oil in present-day refineries. Worldwide, about 400 units are in operation with a total annual capacity of about 600 million tonnes. Commercial catalytic crackers operate at about 550 °C. Since after a contact time in the cracking section (upflow pipe, entrained bed) of only a few seconds the catalyst is largely deactivated by coke at a level of about 1 wt%, the catalyst is routed to a regenerator (fluidized bed), where the coke is burned off at temperatures of 700 °C with air to a level of less than 0.1%. The catalyst is returned pneumatically to the catalytic cracking section. 

Reduced catalyst is then reoxidized with air, in a separate regeneration reactor, to regenerate the active form. This innovation followed the snccessful introduction of conventional fluidized bed operation by Alusuisse and other companies in 1983. Physical circulation of a fluidized bed of catalyst particles, or microspheres, is an unusual technology and has been developed commercially only for the fluid catalytic cracking of heavy gas oils and the SASOL version of the Fischer-Tropsch Synthol process. Success depends not only on an active and selective catalyst but also on the resistance of the catalyst to attrition during the transfer from the reactor to the regenerator and back agaiir... 

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