Preheating: The feedstock, usually vacuum gas oil, is preheated before entering the reactor. Cracking: The preheated feedstock is introduced into the reactor where it contacts the catalyst. The catalyst, in a fluidized state, promotes the breaking of carbon-carbon bonds in large molecules, resulting in smaller, more valuable hydrocarbons. Separation: The cracked hydrocarbon vapors are separated from the catalyst particles in a cyclone separator. Recovery: The cracked products are further separated in a fractionator into various streams such as gasoline, light gases, and heavy cycle oils.
