Patent ID: 8864979

Claim:
A process for fluid catalytic cracking, comprising: A) sending a first catalyst from a first riser reactor to a regeneration vessel having a first stage and a second stage, wherein the first stage is positioned above the second stage; B) sending a second catalyst from a second riser reactor to the regeneration vessel, wherein the first catalyst is sent to the first stage and the second catalyst is sent to the second stage of the regeneration vessel; C) wherein a first line communicates the first catalyst from the first riser reactor to the regeneration vessel, a second line communicates the first catalyst to the first riser reactor from the regeneration vessel, a third line communicates the second catalyst from the second riser reactor to the regeneration vessel, and a fourth line communicates the second catalyst to the second riser reactor from the regeneration vessel; D) wherein the first line contains a first valve, the second line contains a second valve, the third line contains a third valve, and the fourth line contains a fourth valve; and E) wherein a standard deviation of the pressure differentials across all four valves is no more than about 20 kPa.