Fluid Catalytic Cracking – continued.

Cracked hydrocarbons leave the reactor at the top and are routed to a fractionator.

Heavy crude oil collects at the bottom of the fractionator (stream C). Some of this oil is used by the reboiler and the rest is routed to slurry settler. Crude oil settles at the bottom of the settler and is recycled back to the reactor inlet as shown.

A typical FCC process involves mixing a preheated hydrocarbon charge with hot, regenerated catalyst as it enters the riser leading to the reactor. The charge is combined with a recycle stream within the riser, vaporized, and raised to reactor temperature (900-1,000 deg F or 480-540 deg C) by the hot catalyst. As the mixture travels up the riser, the charge is cracked at 10-30 psi.