Patent ID: 8062506

Claim:
A fluid catalytic cracking process, comprising: combining a catalyst and a fluidizing medium in a bottom zone of an enlarged lower section of a riser in order to create a fluidized bed having a superficial gas velocity of between about 90 and about 150 centimeters per second (about 3 and about 5 feet per second), said enlarged lower section having a diameter and a wall; passing said catalyst in said fluidized bed upwardly in said riser; injecting a high carbon residue contaminated feedstock upwardly into said enlarged lower section from an opening positioned above said bottom zone and at a distance of at least about 10% of said diameter away from a closest part of said wall; cracking said high carbon residue contaminated feedstock in the presence of said catalyst to produce a cracked stream; and separating said catalyst from said cracked stream.