Patent ID: 8551326

Claim:
Process for catalytic cracking of a hydrocarbon feedstock with a boiling point that is greater than 350° C., implementing a fine control of the residual coke level on the regenerated catalyst, whereby said process comprises: reacting in at least one reaction zone that brings into contact, in a transported bed, the hydrocarbon feedstock to be treated and the catalyst, and regenerating the coked catalyst used in the reaction in a regeneration zone at the output of the reaction zone, whereby said regeneration zone is divided into a first regeneration stage ( 2 ) that contains a fluidized bed working in partial combustion, generating a catalyst whose residual coke rate is between 0.3% and 0.7%, and a second regeneration stage ( 8 ) that contains a fluidized bed that is placed in series relative to the first regeneration stage, and working in total combustion and generating a catalyst whose residual coke rate is less than 0.15%, whereby the catalyst is transported between the first regeneration stage ( 2 ) and the second regeneration stage ( 8 ) by a transfer line ( 9 ) fed by a gas flow rate ( 10 ) and the catalyst flow rate in the transfer line ( 9 ) is controlled by a plug valve ( 11 ) located at the bottom of the transfer line ( 9 ), whereby the regenerated catalyst that is obtained following the mixing of the partially regenerated and totally regenerated catalysts has a residual coke rate that is greater than 0.15%, whereby said coke rate is obtained by the control of the circulation of the totally regenerated catalyst that is obtained at the output of the second regeneration stage, such that: a portion of the catalyst from the first regeneration stage ( 2 ) running in partial combustion is sent to a fluidized dedicated chamber ( 23 ), and the catalyst from the second regeneration stage ( 8 ) running in total combustion is sent to the fluidized dedicated chamber ( 23 ) through the following: a) a fluidized chamber ( 16 ) that works at a fluidization speed of between 0.05 m/s and 0.1 m/s, the catalyst descending into this chamber at a speed that is less than 0.5 m/s, b) a dense fluidized pipe ( 20 ) that works at a transport speed of the catalyst of between 1 and 3 m/s, c) a valve ( 21 ) for control of the flow rate of catalyst that is slaved to the level of catalyst in the second regeneration stage ( 8 ) said valve ( 21 ) being located up flow of a dedicated fluidized chamber ( 23 ), wherein said dedicated fluidized chamber ( 23 ) operates at a fluidization speed that is less than 10 cm/s, and sending the regenerated catalyst from the dedicated fluidized chamber ( 23 ) to the reaction zone.