Double unit catalytic cracking

Claim 1

A PROCESS FOR CATALYTICALLY CRACKING A FIRST FEED STOCK CONTAINING CATALYST-CONTAMINATING METALS IN A FIRST CRACKING UNIT UNCLUDING A FIRST REACTOR AND A FIRST REGENERATOR AND A SECOND FEED STOCK CONTAINING A LESSER AMOUNT OF CONTAMINATING METALS IN A SECOND CRACKING UNIT INCLUDING A SECOND REACTOR AND A SECOND REGENERATOR, THERE BEING A SMALL CATALYST LOSS AND REPLACEMENT IN THE TWO UNITS AMOUNTING TO A FRACTION OF A PERCENT OF THE AMOUNT CIRCULATED PER DAY, WHICH PROCESS COMPRISES CIRCULATING CATALYST FROM SAID FIRST REACTOR TO SAID FIRST REGENERATOR FOR REGENERATION AND BACK TO SAID FIRST REACTOR IN ADMIXTURE WITH SAID FIRST FEED STOCK; CIRCULATING CATALYST FROM SAID SECOND REACTOR TO SAID SECOND REGENERATOR FOR REGENERATION AND BACK TO SAID SECOND REACTOR IN ADMIXTURE WITH SAID SECOND FEED STOCK; PASSING SUFFICIENT NEW CATALYST TO SAID SECOND UNIT TO REPLACE SUBSTANTIALLY ALL CATALYST DISCARDED FROM THE TWO UNITS; WITHDRAWING FROM SAID FIRST UNIT SUBSTANTIALLY ALL METAL CONTAMINATED CATALYST TO BE DISCARDED FROM THE TWO UNITS; PASSING CRACKED EFFLUENT FROM SAID SECOND UNIT THRU A CATALYST RECOVERY SYSTEM THEREIN AND OPERATING SAID RECOVERY SYSTEM SO AS TO PASS AT LEAST ALL REQUIRED RELATIVELY CLEAN MAKE-UP CATALYST FOR SAID FIRST UNIT TO THE LOWER SECTION OF A FIRST FRACTIONATOR TO RECOVER HYDROCARBONS THEREFROM WHEREBY SAID MAKE-UP CATALYST IS RECOVERED IN A CATALYST-OIL SLURRY FROM THE BOTTOM OF SAID FRACTIONATOR WITHOUT DECANTING; PASSING SAID SLURRY TO SAID FIRST REACTOR TO PROVIDE ALL OF THE MAKE-UP CATALYST FED THERETO; PASSING CRACKED ELLFUENT FROM SAID FIRST REACTOR, CONTAINING SUBSTANTIALLY LESS CATALYST THAN AFORESAID EFFLUENT, TO A SECOND FRACTIONATOR TO RECOVER HYDROCARBONS THEREFROM; AND SEPARATELY RECOVERING CRACKED HYDROCARBONS FROM SAID FRACTIONS.