Removal of contaminants from gas oils produced by fluid coking

Claim 1

IN A FLUID COKING PROCESS WHEREIN A CONTAMINANTSCONTAINING CHARGING STOCK IS INJECTED INTO A FLUIDIZED BED OF PARTICULATE SOLIDS MAINTAINED AT A COKING TEMPERATURE, VAPOROUS PRODUCTS BEING THEREBY PRODUCED, SAID VAPORS BEING WITHDRAWN OVERHEAD THROUGH A SOLIDS SEPARATION ZONE AN INTRODUCED INTO A SCRUBBING ZONE DIRECTLY OVER WHICH IS POSITIONED A FRACTIONATION ZONE, WHEREIN VAPORS ARE COOLED IN SAID CRUBBING ZONE TO BELOW ABOUT 850*F. TO CONDENSED OUT HEAVY ENDS HAVING A NOMINAL INITIAL BOILING ABOVE 700*F., THE HEAVY ENDS COLLECTING IN THE BOTTOM OF SAID SCRUBBING ZONE, AND WHEREIN AT LEAST A PORTION OF THE HEAVY ENDS ARE REMOVED, COOLED AN RETURNED TO THE UPPER PORTION OF SAID SCRUBBING ZONE TO SERVE AS REFLUX OIL, THE IMPROVEMENT WHICH COMPRISES FRACTIONALLY DISTILLING IN THE FRACTIONATION ZONE IMMEDIATELY ABOVE SAID SCRUBBING ZONE THE REMAINDER OF SAID VAPORS TO OBTAIN A CONTAMINANT-CONTAINING HEAVY GAS OIL HAVING AN INITIAL BOILING POINT ABOVE 700*F. AND A FINAL BOILING POINT BELOW 1300*F. AND TO OBTAIN A LOWER BOILING GAS OIL HAVING AN INITIAL BOILING POINT IN THE RANGE OF 300-500*F. AND A CONTAMINANT LEVEL BELOW 0.3 POUND NICKEL EQUIVALENT PER BARREL OF CHARGING STOCK, INTERNALLY RETURNING ALL OF SAID HEAVY GAS OIL AS REFLUX TO SAID SCRUBBING ZONE, WITHDRAWING A PORTION OF SAID LOWER BOILING GAS OIL FROM SAID FRACTIONATION ZONE AS PRODUCT, AND RETURNING THE REMAINDER OF SAID LOWER BOILING GAS OIL TO SAID FRACTIONATION ZONE BELOW THE POINT OF LOWER BOILING GAS OIL DRAWOFF.