Fluid catalytic cracking, main process for
gasoline production, has three main steps, reaction, product separation and
regeneration.
The figure shows the flowchart of fluid catalytic process. The catalyst rise receives preheated petroleum feedstock and recycle slurry oil from the distillation column. They are then vaporized and cracked into low molecular weight hydrocarbons. These vapors fluidize the catalyst particles and the cracking reaction takes place throughout the column.
In the reactor, vapor
products are separated from catalysts and the later flows down to stripping
section where any vapor left is removed using two stage cyclones (see No 5 ) The catalyst now is ready to be sent to catalyst regenerator. In the
regenerator, the coke formed during the cracking processes is removed by burning
and thus recovering the active sites of the catalyst. About 6 % wt. of feedstock in FCC process is converted into
coke.Since the reaction is exothermic, the heat released is
used in vaporization of the feedstock. The catalysts withdrawal (No 6) allows entrained gas to be removed. The hot flue gas exits the regenerator
and the entrained gas is removed from the catalysts in the cyclones.
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Source:
Nee J.R.D., Harding R.H., Yaluris G., Zhao C.,
Dougan T.J., Riley J.R., 2004, Fluid catalytic cracking(FCC), catalysts and
additives, Kirk-Othemer Encyclopedia of chemical technology