Abstract: A slurry feed of a heavy hydrocarbon feedstock and coke-inhibiting additive particles together with a hydrogen-containing gas, are fed upward through a confined hydrocracking zone in a vertical, elongated, cylindrical vessel with a generally dome-shaped bottom head. A mixed effluent is removed from the top containing hydrogen and vaporous hydrocarbons and liquid heavy hydrocarbons. The slurry feed mixture and a portion of the hydrogen-containing gas are fed into the hydrocracking zone through an injector at the bottom of the dome-shaped bottom head and the balance of the hydrogen-containing gas is fed into the hydrocracking zone through injection nozzles arranged within of the hydrocracking zone at a location above the slurry-feed injector. The combined slurry feed and hydrogen-containing gas are injected at a velocity whereby the additive particles are maintained in suspension throughout the vessel and coking reactions are prevented.

Abstract: A process for hydrocracking a heavy hydrocarbon oil feedstock, a substantial portion of which boils above 524.degree. C. is described which includes the steps of: (a) passing a slurry feed of a mixture of heavy hydrocarbon oil feedstock and from about 0.01-4.0% by weight (based on fresh feedstock) of coke-inhibiting additive particles upwardly through a confined vertical hydrocracking zone, the hydrocracking zone being maintained at a temperature between about 350.degree. and 600.degree. C. a pressure of at least 3.

Abstract: A process is described for controlling the size of additive or catalyst particles mixed with heavy hydrocarbon oil feedstock containing asphaltenes and metals and being subjected to hydrotreating. A slurry feed of a mixture of the heavy hydrocarbon oil feedstock and coke-inhibiting additive particles or catalyst particles is passed upwardly through a confined vertical hydrotreating zone in the presence of hydrogen gas, while removing from the top of the hydrotreating zone a mixed effluent containing a gaseous phase comprising hydrogen and vaporous hydrocarbon and a liquid phase comprising heavy hydrocarbon. The mixed effluent is passed through a separation vessel, while withdrawing from the top of the separator a gaseous stream comprising hydrogen and vaporous hydrocarbons and withdrawing from the bottom of the separator a liquid stream comprising heavy hydrocarbons and particles of coke-inhibiting additive or catalyst.

Abstract: A process for hydrocracking a heavy hydrocarbon oil feedstock, a substantial portion of which boils above 524.degree. C. is described which includes the steps of: (a) passing a slurry feed of a mixture of heavy hydrocarbon oil feedstock and from about 0.01-4.0% by weight (based on fresh feedstock) of coke-inhibiting additive particles upwardly through a confined vertical hydrocracking zone, the hydrocracking zone being maintained at a temperature between about 350.degree. and 600.degree. C. a pressure of at least 3.