Hydrocracking of heavy hydrocarbon oils with the use of a thermal hydrocracking-multitage fractionation zone

Claim 1

THE PROCESS FOR HYDROCRACKING HEAVY HYDROCARBON OIL BOILING ABOVE 975*F. WHICH COMPRISES PASSING SAID OIL DOWNWARDLY FROM STAGE TO STAGE THROUGH A THERMAL HYDROCRACKING-MULTISTAGE FRACTIONATION ZONE SUSBTANTIALLY FREE OF SOLIDS AND MAINTAINED UNDER NON-COKING CONDITIONS, INCLUDING A TMEPERATURE OF LESS THAN 900*F., SAID FEED OIL BEING INTRODUCED INTO THE UPPER PORTION OF SAID ZONE BELOW THE UPPERMOST FRACTIONATION STAGE THEREOF, SEPARATELY INTROCUDING HYDROGEN TOT HE LOWER PORTION OF EACH OF THE FRACTIONATION STAGES OF SAID THERMAL HYDROCRACKING-MULTISTAGE FRACTIONATION ZONE, ALLOWING SAID HYDROGEN TO PASS UPWARDLY THROUGH THE HYDROCARBON OIL IN EACH OF SAID FRACTIONATION STAGES TO THEREBY PARTIALLY HYDROCRACK AND VAPORIZE SAID OIL AND CONVERT AT LEAST ABOUT 75% OF SAID OIL BOILING ABOVE 975*F. TO MATERIAL BOILING BELOW 975*F., WITHDRAWING LIQUID HYDROCARBON FROM THE LOWER PORTION OF SAID THERMAL HYDROCRACKING-MULTISTAGE FRACTIONATION ZONE AND RECYCLING AT LEAST A PORTION OF SUCH VAPOROUS PRODUCT TO A FRACTONATION STAGE IN THER UPPER PORTION OF SAID ZONE ABOVE THE FRACTONATION STAGE INTO WHICH THE FEED OIL IS INTRODUCED, SEPARATELY WITHDRAWING