FROM THE VESSEL. THE VESSEL COMPRISES A SPHERICAL SHELL HAVING A HORIZONTAL GRID MOUNTED IN THE LOWER PART OF THE SHELL ON WHICH AN EXPANDABLE PARTICULATE CATALYST IS SUPPORTED. A FEED CONDUIT FOR PASSING HYDROCARBON OIL FEEDSTOCK AND HYDROGEN CONTAINING GAS IS CONNECTED TO THE BOTTOM OF THE VESSEL AND OPENS INTO THE VESSEL BELOW THE GRID. A LIQUID DRAWOFF CONDUIT IS CONNECTED TO THE VESSEL AND OPENS BELOW THE MIDPOINT OF THE VESSEL, AND PREFERABLY ABOVE THE LEVEL OF THE EXPANDED CATALYST BED. A SECOND HORIZONTAL GRID IS HORIZONTALLY MOUNTED IN THE UPPER HALF OF THE SPHERICAL VESSEL AND ACTS TO SUPPORT FIXED CATALYST BED FOR HYDROTREATING HYDROCARBON VAPOR A VAPOR EFFLUENTS WITHDRAWAL CONDUIT IS CONNECTED TO AND OPENS INTO THE REACTOR ABOVE THE FIXED CATALYST BED.

A PROCESS FOR THE HYDROTREATING OF HYDROCARBON OIL AND THE APPARATUS THEREFOR ARE DISCLOSED HEREIN. THE PROCESS COMPRISES FEEDING A HEAVY HYDROCARBON OIL FEED AND A HYDROGEN CONTAINING GAS INTO THE BOTTOM OF A HIGH PRESSURE, HIGH TEMPERATURE SPHERICAL REACTOR VESSEL, PASSING THE OIL AND GAS UPWARDLY THROUGH AN EXPANDED PARTICULATE CATALYST BED IN THE LOWER HALF OF THE VESSEL THEREBY RAPIDLY DECREASING THE UPWARD VELOCITY OF THE UPWARDLY FLOWING GAS AND OIL AND REMOVING THE TREATED HYDROCARBON OIL AT A RATE SUFFICIENT TO MAINTAIN THE UPPER LEVEL OF THE LIQUID HYDROCARBON OIL APPROXIMATELY AT THE MIDPOINT OF THE SPHERICAL VESSEL. PREFERABLY VAPOR PRODUCT IS PASSED UPWARDLY IN THE VESSEL THROUGH A SECOND FIXED CATALYST BED FOR ADDITIONAL HYDROTREATING PRIOR TO BEING WITHDRAWN