Fluid catalytic cracking, reactor selection

Description The DCC process selectively cracks a wide variety of feedstocks into light olefins, with a reactor/regenerator configuration similar to traditional fluid catalytic cracking (FCC) units (see figure). Innovations in catalyst development and process variable selection lead to synergistic benefits and enable the DCC process to produce significantly more olefins than an FCC that is operated for maximum olefins production. 

Among the five modes of OCE reactor operation quoted by ARCO, the one with two-fluid-beds was chosen for all studies except one because its operation, which is similar to a FCC (Fluid Catalytic Cracking) operation, was judged to be most practical. Unfortunately, no process data of this mode are available in the public domain. For this study, the conversion and selectivity of a cyclic fixed-bed mode were adopted for this mode. 

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... 

Weekman Jr., V.W. and D.M. Nace, Kinetics and Catalytic Cracking Selectivity in Fixed, Moving and Fluid-Bed Reactors., AIChE Joum., 16,397,1970. 

Weekman, V. W., and Nace, D. M., Kinetics of catalytic cracking selectivity in fixed, moving and fluid-bed reactors. AIChEJ. 16,397 (1970). 

Economic efficiency of waste plastics processing depends on the methods of their selection and preparation for processing as well as the cost of thermal or catalytic treatment, i.e. the cost of investment and exploitation of the cracking plant. For instance the main characteristic of fluid-bed reactors is the possibility of exploitation of large-scale units (at least 50000 tons or more per year), low cost of exploitation, but accompanied by large investment and feed delivery costs. And on the other hand, smaller reactors can be built on a smaller scale, a few thousand tons per year output, lower investment costs and lower feed deliveries (processing of local wastes in limited area), but operated with larger exploitation costs. 

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