Fluid Catalytic Cracking

The figure provided here illustrates a schematic for a fluid catalytic cracking system.

In reference to the figure note that the raw charge of preheated oil is pumped up the reactor riser. The stream “A” indicates regenerated catalyst. The fresh catalyst and hot oil are mixed and rise up in the riser. The cracking reactions take place as oil rises up in the riser as well as in the reactor.

Section “D” of the system is known as catalyst stripper. In this section, steam is used to remove hydrocarbons from the catalyst beads.

Spent catalyst is routed to a regenerator in stream “B”. During the cracking process, some carbon is produced which tends to adhere to the catalyst beads – thereby making the catalyst ineffective. High pressure air is blown into the regenerator to burn off the carbon from the catalyst beads.

Removal of carbon reactivates the catalyst and it is put back into service through stream A.