Catalytic cracking process and apparatus

Claim 1

A FLUID CATALYTIC CRACKING PROCESS WHICH COMPRISES REGENERATING CONTAMINATED FLUIDIZED CRACKING CATALYST PARTICLES BY REMOVING THE CONTAMINANT BY OXIDATIVE COMBUSTION FROM THE CATALYST PARTICLES IN A REGENERATOR PROVIDED WITH A PLURALITY OF REGENERATION ZONE, SUPERPOSED ONE UPON ANOTHER, IN WHICH THE AMOUNT OF CONTAMINANT PRESENT ON THE CRACKING CATALYST IN AN UPPER ZONE IS GREATER THAN THAT WHICH IS PRESENT ON THE CRACKING CATALYST IN A LOWER ZONE THEREOF, THE AMOUNT OF CONTAMINANT IN SAID UPPER ZONE BEING ABOUT 0.4 TO ABOUT 1.0 WEIGHT PERCENT AND THE AMOUNT OF CONTAMINANT IN SAID LOWER ZONE BEING ABOUT 0.1 TO ABOUT 0.6 WEIGHT PERCENT; ADMIXING A HYDROCARBON CHARGE STOCK CONTAINING APPRECIABLE AMOUNTS OF DELETERIOUS MATERIALS WITH PARTIALLY REGENERATED CRACKING CATALYST OBTAINED FROM AN UPPER REGENERATION ZONE; SUBJECTING SUCH MIXTURE TO RELATIVELY MILD CRACKING CONDITIONS IN A FIRST REACTION ZONE FOR A TIME SUFFICIENT TO RELEASE A MAJOR PORTION OF SAID DELEFERIOUS MATERIALS IN SAID FIRST REACTION ZONE AND DEPOSIT CONTAMINANT ON THE CRACKING CATALYST THEREIN; ADMIXING A HYDROCARBON CHARGE STOCK CONTAINING SUBSTANTIALLY LESS OF THE DELETERIOUS MATERIALS THAN IS PRESENT IN THE CHARGE STOCK PASSED TO FIRST REACTION ZONE WITH A REGENERATION CRACKING CATALYST OBTAINED FROM A LOWER REGENERATION ZONE; SUBJECTING SAID LAST NAMED MIXTURE TO ELEVATED TEMPERATURES IN A SECOND REACTION ZONE, THEREBY FORMING A RELATIVELY LOWER BOILING HYDROCARBON PRODUCT AND DEPOSITING CONTAMINANT ON THE CATALYST PARTICLES THEREIN; CONTINUOUSLY RECYCLING CONTAMINATED CATALYST FROM EACH OF THE TWO REACTION ZONES TO THE REGENERATOR AND CONTINUOUSLY WITHDRAWING THE CRACKED PRODUCT FROM EACH OF THE TWO REACTION ZONES.