Regeneration of finely divided catalysts

Claim 1

PROCESS FOR THE REGENERATION OF SPENT CATALYST BY BURNING CARBONACEOUS DEPOSITS THEREFROM WHICH COMPRISES INTRODUCING AIR INTO THE BOTTOM OF A FLUIDIZED BED OF CRACKING CATALYST DEACTIVATED IN CATALYTIC CRACKING OF A HYDROCARBON OIL AND UNDERGOING REGENERATION IN APPARATUS PROVIDED THEREFOR INCLUDING AS AN INTEGRAL REGENERATION ZONE A FIRST AND A SUPERPOSED SECOND SPENT CATALYST COMBUSTION SPACE UNDER REGENERATION CONDITIONS MAINTAINED AT A TEMPERATURE AND FOR A RESIDENCE TIME SUFFICIENT TO PROMOTE THE COMBUSTION OF A SUBSTANTIAL PORTION OF SAID CARBONACEOUS DEPOSITS FROM SAID SPENT CATALYST, PASSING THE AIR UP THROUGH SAID BED AT A RATE SUFFICIENT TO MAINTAIN THE CATALYST IN A FLUIDIZED CONDITION IN SAID REGENERATION ZONE AND TO PROVIDE AN EXIT GAS FROM THE FIRST SPACE CONTAINING AT LEAST ABOUT 2 PERCENT OXYGEN, MAINTAINING SAID REGENERATION ZONE FILLED WITH CATALYST, CONTINUOUSLY WITHDRAWING REGENERATED CATALYST PRODUCT BY GRAVITY FLOW DIRECTLY FROM THE FLUIDIZED BED IN THE FIRST SPACE OF THE REGENERATION ZONE, PASSING OUT OF THE TOP OF THE FIRST SPACE OF THE REGENERATION ZONE PARTIALLY UTILIZED REGENERATION GAS CONTAINING IN SUSPENSION AT LEAST 1.5 KILOGRAMS OF CATALYST PER CUBIC METER OF GAS, CONTINUOUSLY ADDING FRESHLY SPENT CATALYST TO BE REGENERATED TO SAID SUSPENSION INTERMEDIATE SAID FIRST AND SECOND COMBUSTION SPACES AND PASSING THE RESULTING MIXTURE UP THROUGH SAID SECOND COMBUSTION SPACE COMPRISING A VERTICALLY EXTENDED SPACE OF SUBSTANTIALLY SMALLER CROSS-SECTION THAN SAID FIRST SPACE TO AN UPPER SEPARATION AND COLLECTING ZONE OF LARGER CROSSSECTION THAN THE SECOND SPACE, WITHDRAWING FLUE GAS SUBSTANTIALLY FREE OF CATALYST FROM SAID UPPER SEPARATION AND COLLECTING ZONE, PASSING CATALYST FROM THE COLLECTING ZONE BY CONTROLLED GRAVITY FLOW TO SAID FIRST COMBUSTION SPACE OF THE REGENERATION ZONE, AND CONTROLLING THE CONCENTRATION OF SUSPENDED CATALYST PASSING OUT OF THE TOP OF SAID FIRST SPENT CATALYST COMBUSTION SPACE AND INTO THE SECOND SPACE AT A VALUE OF AT LEAST 1.5 KILOGRAMS OF CATALYST PER CUBIC METER OF GAS BY CONTROLLING THE RATE OF SAID LAST MENTIONED GRAVITY FLOW OF CATALYST FROM THE COLLECTING ZONE TO THE SAID FIRST SPENT CATALYST COMBUSTION SPACE OF SAID INTEGRAL REGENERATION ZONE.