Fluid coking recycle operation

Claim 1

IN A PROCESS FOR COKING A HEAVY HYDROCARBON OIL CHARGE STOCK BY CONTACTING THE OIL CHARGE STOCK AT A COKING TEMPERATURE WITH FLUIDIZED COKE PARTICLES IN A COKING ZONE AT A TEMPERATURE IN THE RANGE OF ABOUT 900*F. TO 1200* F. WHEREIN THE OIL IS CONVERTED TO PRODUCT VAPORS AND CARBONACEOUS MATERIAL IS CONTINUOUSLY DEPOSITED ON THE COKE PARTICLES, PASSING PRODUCT VAPORS FROM THE COKING ZONE TO A SCRUBBING-FRACTIONATION ZONE, FRACTIONATING THE PRODUCT VAPORS IN THE SCRUBBING-FRACTIONATION ZONE TO SEPARATE A HEAVY RESIDUAL BOTTOMS FRACTION TO BE RECYCLED TO THE COKING ZONE FROM MORE VOLATILE GAS OIL AND LIGHTER FRACTIONS, SENDING A PORTION OF THE COKE PARTICLES FROM THE COKING ZONE TO A HEATING ZONE TO INCREASE THE TEMPERATURE OF THE PARTICLES AND RETURNING A PORTION OF THE HEATED PARTICLES FROM THE HEATING ZONE TO THE COKING ZONE, THE IMPROVEMENT FOR INCREASING CONVERSION PER PASS AND FOR INCREASING THE AVERAGE BOILING POINT OF SAID RECYCLE HEAVY RESIDUAL BOTTOMS FRACTION WHEN THE INITIAL BOILING POINT OF SAID RECYCLE HEAVY RESIDUAL BOTTOMS FRACTION IS BETWEEN ABOUT 850*F. AND 950*F. WHICH COMPRISES CONTACTING SAID RECYCLE HEAVY RESIDUAL BOTTOMS FRACTION IN THE LIQUID PHASE WITH AIR AT A TEMPERATURE BELOW ITS CRACKING TEMPERATURE AND IN THE RANGE OF ABOUT 550*F. TO 700*F. IN AN OXIDATION ZONE TO OXIDIZE SAID RECYCLE HEAVY BOTTOMS FRACTION TO A COMBINED OXYGEN CONTENT OF ABOUT 4 TO 6 WT. PERCENT AND FEEDING THE ENTIRE OXIDIZED FRACTION SUBSTANTIALLY FREE OF EXTRANEOUS AIR TO THE COKING ZONE.