Abstract: A process for the regeneration of coke-contaminated fluidizable catalytic cracking catalyst wherein the regeneration flue gas having a reduced concentration of carbon monoxide and regenerated catalyst having a reduced residual carbon content are obtained. By this method a fluidized dense catalyst phase of coke-contaminated catalyst is regenerated with an excess amount of oxygen-containing regeneration gas at an elevated temperature such that there is a controlled afterburn of carbon monoxide to carbon dioxide in the dilute catalyst phase whereby a flue gas having a carbon monoxide content of from 0 to 500 ppm is obtained. The residence time of catalyst in the fluidized dense catalyst phase is adjusted to provide a low level of residual carbon-on-regenerated-catalyst.

Abstract: An improved method for controlling the fluidized dense catalyst phase temperature in the regeneration zone of a fluid catalytic cracking unit. In this method, the level of the fluidized catalyst bed above the riser discharge in the reaction vessel is adjusted in response to a change detected in the temperature of the fluidized dense catalyst phase of the regeneration zone. Adjustment of the catalyst bed level in the reaction zone affects the coke laydown on the catalyst in the reactor and, consequently, the amount of heat liberated in the regeneration zone upon combustion of the coke contained in the partially deactivated catalyst. A reactor bed level is attained where the resulting coke laydown on the catalyst is sufficient to maintain the desired temperature in the fluidized dense catalyst phase.

Abstract: An improved method is disclosed for controlling the temperature of the fluidized dense catalyst phase of the regeneration zone in a fluid catalytic cracking unit, wherein the coke laydown in the reaction zone is at a level such that the coke concentration of the partially deactivated catalyst from the reaction zone is not sufficient to provide the heat required to maintain the controlled temperature in the fluidized dense catalyst phase of the regeneration zone. In this method, torch oil is added to the partially deactivated catalyst in the spent catalyst transfer line in an amount such that the catalyst charged to the regeneration zone contains sufficient combustible material to provide the heat necessary to maintain the fluidized dense catalyst phase of the regeneration zone at the controlled temperature.