Process for recovering power from a fluid catalytic cracking unit used particularly for the treatment of heavy charges

A process for fluid catalytic cracking of a hydrocarbon charge in a reaction zone, whereafter the catalyst is withdrawn from the reaction zone and then partially regenerated in a first regeneration zone, withdrawn from said first regeneration zone and fed to a second regeneration zone whose pressure is lower than the pressure prevailing in said first regeneration zone, said process being characterized in that the fumes withdrawn from the first regeneration zone, after removal therefrom of the catalyst fine particles eventually contained therein, are supplied to a turbine comprising several stages, the pressures in each stage decreasing in the direction of flow of the fumes passing therethrough, said fumes being thus introduced in the stage of higher pressure of the turbine, said process being also characterized in that the fumes withdrawn from the second regeneration zone, after removal therefrom of the fine catalyst particles eventually contained therein, are conveyed to said turbine in a stage thereof other than that to which are supplied the fumes withdrawn from the first regeneration zone, the stage at which are supplied the fumes from the second regeneration zone being at a pressure lower than or equal to the pressure of said fumes in the second regeneration zone.