BRPI0715107A2 - process for hydrocracking a hydrocarbon feedstock - Google Patents

Abstract

The process for hydrocracking a hydrocarbon feedstock A catalytic hydrocracking process is described wherein a liquid phase stream comprising a hydrocarbonaceous feedstock (1), a liquid phase effluent from a hydrocracking zone (16), and hydrogen in a hydrogen concentration sufficiently low to maintain a continuous liquid phase system is fed into a hydrogenation zone (4) to produce a first hydrocarbon stream comprising low sulfur and nitrogen hydrocarbons. The resulting low sulfur and nitrogen hydrocarbons are introduced into a hydrocracking zone (13) with a hydrogen concentration sufficiently low to maintain a continuous liquid phase system to produce hydrocarbon depletion zone effluent (16) that supplies hydrocarbons. in the lowest boiling range.

Description

FIELD OF THE INVENTION FIELD OF THE INVENTION

The art field to which this invention relates is the catalytic conversion of hydrocarbons into usable hydrocarbon products. More particularly, the invention relates to catalytic hydrocracking. BACKGROUND OF THE INVENTION

The present invention relates to hydrocracking a hydrocarbon feedstock. Petroleum refineries often generate desirable products such as turbine fuel, diesel fuel and other products known as intermediate distillates, as well as lower boiling hydrocarbon liquids such as naphtha and gasoline, by hydrocracking a hydrocarbon feedstock. crude oil or heavy fractions thereof. Feed loads most frequently hydrocracked are heavy gas oils and oils recovered from crude oil by distillation. A typical heavy diesel comprises a substantial portion of hydrocarbon components having a boiling point above 371 ° C (700 ° F), usually at least 50 percent by weight with a boiling point above 371 ° C (700 ° F). A typical vacuum gas oil typically has a boiling range between 315 ° C (600 ° F) and 565 ° C (1,050 ° F).

Hydrocracking is generally performed by contacting in a vessel or hydrocracking reaction zone the diesel or other feedstock to be treated with a suitable hydrocracking catalyst under elevated temperature and pressure conditions in the presence of hydrogen as a separate phase. in a biphasic reaction zone to generate a product containing a desired distribution of hydrocarbon products by the refinery. Operating conditions and hydrocracking catalysts in a hydrocracking reactor influence the yield of hydrocracking products.

Traditionally, the fresh feed charge for a hydrocracking process is first introduced into a denitrification and desulfurization zone having hydrogen in a gas phase and particularly suitable for removal of sulfur and nitrogen contaminants and subsequently introduced into a catalyst-containing hydrocracking zone. hydrocracking and having hydrogen in a gas phase. Another method of hydrocracking a fresh feedstock is to introduce the fresh feedload and effluent from the hydrocracking zone into the denitrification and desulphurization zone. The resulting effluent from the hydrocracking zone is separated to produce desired hydrocracking products and unconverted feedstock which is then introduced into the hydrocracking zone. Previously, at least a major portion of the hydrogen present in reaction zones was present in a gas phase. This method or technique is commonly referred to as a "drip bed" wherein the continuous phase is gaseous and not liquid.

Although a wide variety of

Since process, operating conditions and catalysts have been used in commercial activities, there is always a demand for new hydrocracking methods that provide lower costs, easier construction, higher net product yields and higher quality products.

DESCRIPTION OF THE INVENTION

US 5,720,872 (Gupta) discloses a process for hydroprocessing liquid feed loads at two or more hydroprocessing stages which are in separate reaction vessels and wherein each reaction stage contains a hydroprocessing catalyst bed. The liquid product of the first reaction stage is sent to a low pressure removal stage and removed from hydrogen sulfide, ammonia and other dissolved gases. The stream of the removed product is then sent to the next downstream reaction stage, the product of which is also removed from dissolved gases and sent to the next downstream reaction stage to the last reaction stage, the liquid product of which It is removed from dissolved gases and collected or carried forward for further processing. The flow of treating gas is in a direction opposite the direction in which the reaction stages are staged for the flow of liquid. Each removal stage is a separate stage, but all stages are contained in the same extraction vessel.

US 3,328,290 (Hengstebeck) discloses a two-stage hydrocarbon hydrocracking process wherein the feed is pretreated in the first stage.

US 5,403,469 (Vauk et al) discloses a parallel hydrotreating and hydrocracking process. Effluent from the two processes are combined in the same separation vessel and separated into a vapor comprising hydrogen and a hydrocarbon-containing liquid. Hydrogen is shown to be supplied as part of both hydrocracking and hydrotreating feed streams.

US 5,980,729 (Kalnes et al) discloses a hydrocracking process in which a hydrocarbonaceous feedstock and a hydrogen containing hot hydrocracking zone effluent passes into a denitrification and desulphurization reaction zone to produce hydrogen sulfide and ammonia to clean the fresh feed load in this way. The uncooled hot effluent resulting from the denitrification and desulfurization zone is hydrogen removed in a removal zone maintained at essentially the same pressure as the previous reaction zone with a hydrogen rich gas stream to produce a vapor stream comprising hydrogen, hydrocarbon compounds with boiling point below the boiling range of the fresh feed charge, hydrogen sulfide and ammonia, and a liquid hydrocarbon stream containing unconverted feed charge. This liquid hydrocarbon stream is introduced into a hydrocracking zone to produce a hydrocracking zone effluent which then joins the fresh feed charge in the manner described above and is subsequently introduced into the denitrification and desulfurization zone.

US 6,106,694 (Kalnes et al) discloses a hydrocracking process in which a hydrocarbon feedstock and a hot hydrocracking zone effluent passes into a denitrification and desulphurization reaction zone to produce hydrogen sulfide and ammonia to clear from it. way the fresh feed load. The uncooled hot effluent resulting from the denitrification and desulfurization zone has hydrogen removed in a removal zone maintained at essentially the same pressure as the previous reaction zone with a hydrogen rich gas stream to produce a vapor stream comprising hydrogen, hydrocarbon compounds with boiling point below the boiling range of the fresh feed charge, hydrogen sulfide and ammonia, and a liquid hydrocarbon stream containing unconverted feed charge. This liquid hydrocarbon stream is subsequently introduced into the hydrocracking zone to produce an effluent which is subsequently introduced into the denitrification and desulphurization reaction zone described above.

US 6,123,835 (Ackerson et al.) And US 6,428,686 (Ackerson et al.) Disclose a hydroprocess where the need to circulate hydrogen through the catalyst is eliminated by mixing hydrogen and the oil feedstock in the presence of a diluent. wherein the solubility of hydrogen is high with respect to the feed load. The oil / diluent / hydrogen solution can then be fed by a catalyst-containing piston flow reactor. BRIEF SUMMARY OF THE INVENTION

The present invention is a catalytic hydrocracking process in one embodiment wherein a liquid phase stream comprising a hydrocarbon feedstock, a liquid phase effluent from a hydrocracking zone, and a hydrogen concentration sufficiently low to maintain a system. The continuous liquid phase is fed into a hydrogenation zone to produce hydrogen sulfide and ammonia and to provide a first hydrocarbon stream comprising low sulfur and nitrogen hydrocarbons. Low sulfur and nitrogen hydrocarbons are introduced into a hydrocracking zone with a hydrogen concentration sufficiently low to maintain a continuous liquid phase system to produce a hydrocracking zone effluent that supplies hydrocarbons in the lowest boiling range. . In preferred embodiments, the first hydrocarbon stream comprising low sulfur and nitrogen hydrocarbons is separated into a high pressure product extractor or by conventional distillation to provide the low sulfur and nitrogen hydrocarbons which are subsequently introduced into the zone. hydrocracking.

In a second embodiment, the present invention is a catalytic hydrocracking process wherein a liquid phase stream comprising a hydrocarbon feedstock, a liquid phase effluent from a hydrocracking zone, and a hydrogen concentration sufficiently low to maintain a system. Continuous liquid phase is fed into a hydrogenation zone to produce hydrogen sulfide and ammonia, and to provide a first hydrocarbon stream comprising low sulfur and nitrogen hydrocarbons.

The first hydrocarbon stream comprising low sulfur and nitrogen hydrocarbons is introduced into a hydrocracking zone with a hydrogen concentration sufficiently low to maintain a continuous liquid phase system to produce a hydrocracking zone effluent. The hydrocracking zone effluent is introduced into a separation zone which in one embodiment is preferably a high pressure product extractor to produce a second hydrocarbon stream containing lower boiling hydrocarbons and a liquid phase hydrocarbon stream comprising unconverted hydrocarbons. which is introduced into the hydrotreating zone in the manner described above. Boiling point hydrocracked hydrocarbons at a temperature range less than that of the hydrocarbon feedstock are recovered. Conventional hydroprocessing operations utilize

leaky bed technique. This technique requires the use of large amounts of hydrogen with respect to the hydrocarbon feedstock, sometimes exceeding 1,685 nm3 / m3 (10,000 SCFB), and requires the use of expensive recycle gas compression. The large amounts of hydrogen with respect to the hydrocarbon feedstock in conventional hydroprocessing operations make this type of operation a continuous gas phase system. It has been found that it is both economical and necessary to have this large excess of hydrogen to effect the desired conversion. The desired conversion can be made with much less hydrogen, and can be economically and efficiently performed with just enough hydrogen to ensure a continuous liquid phase system. A continuous liquid phase system would exist at one end with only enough hydrogen to fully saturate the hydrocarbon feedstock and at the other end where sufficient hydrogen is added to transition to a continuous gas phase system. The amount of hydrogen that is added between these two extremes is dictated by economic considerations. Operation with a continuous liquid phase system avoids the high costs associated with a recycle gas compressor.

Other embodiments of the present invention encompass further details such as types and descriptions of feed loads, hydrocracking catalysts, hydrotreating catalysts, and preferred operating conditions including temperatures and pressures, all of which are hereinafter disclosed in the following discussion of each of these. aspects of the invention. BRIEF DESCRIPTION OF DRAWINGS

The drawings are simplified process flow charts of preferred embodiments of the present invention. The drawings should be schematically illustrative of the present invention, not a limitation thereof. Although the drawings represent the process operating in a downflow mode, it is presented for illustrative purposes and is not intended to exclude an upflow mode of operation. DETAILED DESCRIPTION OF THE INVENTION

The process of the present invention is particularly used for hydrocracking a hydrocarbon oil containing hydrocarbons and / or other organic materials to produce a product containing hydrocarbons and / or lower average boiling and lower average molecular weight organic materials. Hydrocarbon feedstock that can be hydrocracked by the method of the invention includes all mineral oils and synthetic oils (e.g. shale oil, bituminous sand products, etc.) and fractions thereof. Illustrative hydrocarbon feed loads include those containing components boiling above 550 ° F (288 ° C), such as atmospheric gas oils, vacuum gas oils, vacuum and atmospheric de -phalting residues, hydrotreated or mildly hydrocracked waste oils, coke oven distillates, direct run distillates, solvent-asphalted oils, pyrolysis-derived oils, synthetic high-boiling oils, recycle oils and catalytic cracking distillates. A preferred hydrocracking feedstock is a diesel or other hydrocarbon fraction of at least 50 wt.%, And more usually at least 75 wt.% Of its components with boiling point above 3710C (700 ° F). One of the most preferred diesel feed fillers will contain boiling point hydrocarbons above 288 ° C (550 ° F), with better results being obtained with feeds containing at least 25 percent by volume of boiling components between 315 ° C 600 ° F (56 ° C) and 1,050 ° F (565 ° C).

The selected hydrocarbonaceous and hydrogen feedstock are introduced into a hydrotreating reaction zone under hydrotreating reaction conditions. In addition, the effluent resulting from a hydrocracking reaction zone described below is also introduced into the hydrotreating reaction zone. Preferred hydrotreating reaction conditions include a temperature of 204 ° C (400 ° F) to 482 ° C (900 ° F), a pressure of 3.5 MPa (500 psig) to 17.3 MPa (2,500 psig), a spatial hourly liquid velocity of the fresh hydrocarbon feed charge from 0.1 h -1 to 10 h "1 with a hydrotreating catalyst or a combination of hydrotreating catalysts. Only sufficient hydrogen is introduced into the hydrotreating reaction zone to maintain a This means that, unlike conventional hydroprocessing processes operating in a drip bed mode in which it is the gaseous phase which is continuous, the present invention operates in a continuous liquid phase system.

The term "hydrotreating" as used herein refers to a process in which a hydrogen containing treated gas absorbed in the liquid hydrocarbon is used in the presence of suitable catalysts that are basically active for the removal of heteroatoms, such as sulfur and nitrogen, from hydrocarbon feedstock. Suitable hydrotreating catalysts for use in the present invention are any known conventional hydrotreating catalysts and include those comprising at least one Group VIII metal, preferably iron, cobalt and nickel, more preferably cobalt and / or nickel, and at least a Group VI metal, preferably molybdenum and tungsten, in a large surface area support material, preferably alumina. Other suitable hydrotreating catalysts include zeolitic catalysts as well as noble metal catalysts where the noble metal is selected from palladium and platinum. It is within the scope of the present invention that more than one type of hydrotreating catalyst is used in the same reaction vessel. Group VIII metal is typically present in an amount ranging from 2 to 20 weight percent, preferably from 4 to 12 weight percent. Group VI metal will typically be present in an amount ranging from 1 to 25 weight percent, preferably from 2 to 25 weight percent.

In one embodiment of the present invention, the effluent resulting from the hydrotreating reaction zone is introduced directly into a hydrocracking reaction zone to provide lower boiling hydrocarbons. In another embodiment of the present invention, the resulting effluent is introduced into a separation zone which is preferably a high pressure product extractor or conventional fractionation zone to recover lower boiling hydrocarbons and to provide a hydrocarbon stream containing hydrocarbons. boiling point in the range of the fresh feed load that is subsequently introduced into a hydrocracking zone. The high pressure product puller is preferably operated at a temperature of 204 ° C (400 ° F) to 482 ° C (900 ° F) and a pressure of 3.5 MPa (500 psig) to 17.3 MPa (2,500 psig).

In a preferred embodiment where the hydrogenation zone effluent is introduced directly into the hydrocracking zone, the hydrocracking reaction effluent is preferably introduced into a high pressure extractor preferably operated at a temperature of 204 ° C (400 ° F). at 482 ° C (900 ° F) and a pressure of 3.5 MPa (500 psig) to 17.3 MPa (2,500 psig) to produce a vaporous hydrocarbon stream and a liquid hydrocarbon stream containing boiling point hydrocarbons in the range Fresh feed load that is introduced into the hydrogenation zone. In a preferred embodiment where the hydrogenation zone effluent is separated between the hydrogenation zone and the hydrocracking zone, the hydrocracking zone effluent is introduced directly into the hydrogenation zone.

Either way, the feed is introduced into the hydrocracking zone along with the hydrogen added in an amount low enough to maintain a continuous liquid phase system. The hydrocracking zone may contain one or more beds of the same or a different catalyst. In one embodiment, when preferred products are intermediate distillates, preferred hydrocracking catalysts use amorphous bases or low level zeolite bases combined with one or more Group VIII or Group VIB metal hydrogenation components. In another embodiment, when the preferred products are in the boiling range of gasoline, the hydrocracking zone contains a catalyst generally comprising any crystalline zeolite cracking base on which a minor proportion of a hydrogenation component is deposited. of Group VIII metal. Additional hydrogenation components may be selected from Group VIB for incorporation with the zeolite base. Zeolite cracking bases are sometimes referred to in the art as molecular sieves and are usually composed of silica, alumina and one or more exchangeable cations such as sodium, magnesium, calcium, rare earth metals, etc. They are further characterized by crystalline pores of relatively uniform diameter between 4 and 14 angstroms (10 x 10 meters). It is preferred to employ zeolites having a relatively high silica / alumina molar ratio of between 3 and 12. Suitable zeolites found in nature include, for example, mordenite, stilbite, heulandite, ferrierite, dachiardita, chabazite, erionite and faujasite Suitable synthetic zeolites include, for example, the crystalline types Β, X, Y, and L, for example synthetic faujasite and mordenite. with crystalline pore diameters between 8 and 12 angstroms (10 - 10 meters), wherein the silica / alumina molar ratio is 4 to 6. A unique example of a zeolite falling into the preferred group is synthetic Y molecular sieve.

Naturally occurring zeolites are usually found in a sodium form, an alkaline earth metal form, or mixed forms. Synthetic zeolites are almost always prepared first in sodium form. In any case, for use as a cracking base, it is preferable that most or all of the original zeolitic monovalent metals have had ion exchange with a polyvalent metal and / or an ammonium salt followed by heating to decompose the ammonium ions. associated with zeolite, leaving in its place hydrogen ions and / or exchange sites that have now been decationized by additional removal of water. Hydrogen or "decationized" Y zeolites of this nature are more particularly described in US 3,130,006.

Mixed polyvalent metal hydrogen zeolites can be prepared first by ion exchange with an ammonium salt, then partially back-exchanged with a polyvalent metal salt and then calcining. In some cases, such as synthetic mordenite, hydrogen forms can be prepared by direct acid treatment of alkali metal zeolites. Preferred cracking bases are those which are at least 10 percent, and preferably at least 20 percent, metal cation deficient based on initial ion exchange capacity.

A specifically desirable and stable class of zeolites are those in which at least 20 percent of the ion exchange capacity is satisfied by hydrogen ions.

The active metals employed in the preferred hydrocracking catalysts of the present invention as hydrogenation components are those of group VIII, i.e. iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum. In addition to these metals, other promoters may also be employed in conjunction with these, including group VIB metals, for example molybdenum and tungsten. The amount of hydrogenation metal in the catalyst may vary over wide ranges. Generally, any amount between 0.05 percent and 30 percent by weight may be used. For noble metals, it is generally preferred to use 0.05 to 2 percent by weight. The preferred method for incorporating the hydrogenation metal is to contact the zeolite base material with an aqueous solution of a suitable desired metal compound wherein the metal is present in a cationic form. After addition of the selected metal or hydrogenation metals, the resulting catalyst powder is then filtered, dried, precipitated with added lubricants, binders or the like, if desired, and calcined in air at temperatures, for example, from 371 ° - 648 °. C (700 ° - 1,200 ° F) in order to activate the catalyst and decompose ammonium ions. Alternatively, the zeolite component may first be precipitated, followed by the addition of the hydrogenation component and calcination activation. The above catalysts may be employed in undiluted form, or the sprayed zeolite catalyst may be mixed and co-precipitated with other relatively less active catalysts, diluents or binders such as alumina, silica gel, silica alumina co-gels, clay and activated in proportions ranging from 5 to 90 weight percent. These diluents may be employed as such, or they may contain a minor proportion of an added hydrogenation metal, such as a group VIB and / or group VIII metal.

Additional metal promoted hydrocracking catalysts may also be used in the process of the present invention comprising, for example, molecular sieves of aluminophosphate, crystalline chromosilicates and other crystalline silicates. Crystalline chromosilicates are described in more detail in US 4,363,718 (Klotz).

Hydrocracking of the hydrocarbon feedstock in contact with a hydrocracking catalyst is conducted in the presence of sufficiently low concentrations of hydrogen to maintain a continuous liquid phase system and preferably under hydrocracking reactor conditions including a temperature of 232 ° C (450 ° C). ° F) at 468 ° C (875 ° F), a pressure of 500 MPig (3,5 MPa) to 2,500 psig (17,3 MPa) and a liquid space hourly velocity (LHS V) of 0.1 to 30 In accordance with the present invention, the term "substantial conversion to lower boiling products" means not being able to convert at least 5 percent of the volume of the fresh feedstock into products with a lower boiling point. In a preferred embodiment, the conversion per step in the hydrocracking zone is in the range of 15% to 75% More preferably the conversion per pass is in the range of 20% to 60%. The ratio of unconverted boiling hydrocarbons in the hydrocarbon feedstock to hydrocarbon feedstock ratio is 1: 5 to 3: 5. The present invention is suitable for the production of naphtha, diesel or any other desired lower boiling hydrocarbons. During conversions or reactions that occur in the hydrotreating and hydrocracking reaction zones, hydrogen is necessarily consumed and must be replaced by one or more hydrogen entry points located in the reaction zones. The amount of hydrogen added at these locations is controlled to ensure that the system operates as a continuous liquid phase system. The limiting amount of hydrogen that is added is the amount that causes a transition from a continuous liquid phase system to a continuous vapor phase system.

The relative amount of hydrogen required to maintain a continuous liquid phase system in both hydrotreating and hydrocracking zones depends on the specific composition of the hydrocarbon feedstock, the level or amount of conversion to lower boiling hydrocarbon compounds, composition and quantity of the lowest boiling hydrocarbons and the reaction zone temperature and pressure. Those skilled in the art of hydrocarbon conversion and hydrocracking will readily determine the appropriate amount of hydrogen to provide a continuous liquid phase system once all of the above variables have been selected. DETAILED DESCRIPTION OF DRAWINGS

Referring now to Figure 1, a feed stream comprising vacuum gas oil is introduced into the process via line 1 and mixed with an effluent from the hydrocracking zone described below conveyed via line 16. A hydrogen rich gas stream is introduced via line 2 and also joins the feed stream, and the resulting mixture is conveyed via line 3 and introduced into hydrogenation zone 4. Additional hydrogen-rich gas is introduced via lines 5 and 6 into zone of hydrogenation 4 in order to supplement the required hydrogen that is consumed in hydrogenation zone 4. The amount of hydrogen present in hydrogenation zone 4 is low enough to maintain a continuous liquid phase system. The resulting effluent from hydrogenation zone 4 is charged via line 7 and fed into high pressure product extractor 8. A hydrocarbon vapor stream comprising hydrogen sulfide, ammonia and boiling hydrocarbons in the range below the feedstock is removed from high pressure product puller 8 via line 9 and recovered. A liquid hydrocarbon stream containing boiling point hydrocarbon compounds in the feedstock range is removed from the high pressure product puller 8 via line 10 and is joined with a hydrogen rich stream supplied via line Ilea to the resulting mixture. is transported via line 12 and introduced into hydrocracking zone 13. Additional hydrogen is supplied via lines 14 and 15 to hydrocracking zone 13. Hydrogen supplied to hydrocracking zone 13 is sufficiently low to maintain a continuous liquid phase system in it. An effluent resulting from the hydrocracking zone is removed from the hydrocracking zone 13 via line 16 and joins the fresh feed charge provided via line 1 in the manner described above.

Referring now to Figure 2, a feed stream comprising vacuum gas oil is introduced into the process via line 1 and mixed with an effluent from the hydrocracking zone described below conveyed via line 16. A hydrogen rich gas stream is supplied via line 2 and also joins the feed stream, and the resulting mixture is conveyed via line 3 and introduced into hydrogenation zone 4. Additional hydrogen is introduced into hydrogenation zone 4 via lines 5 and 6 The total hydrogen supply to hydrogenation zone 4 is low enough to maintain a continuous liquid phase system. A resulting effluent stream is removed from the hydrogenation zone 4 via line 7 and is joined with a hydrogen-rich gas stream supplied through line 24 in an amount sufficiently low to maintain a continuous liquid phase system and the resulting mixture is transported via line 25 and introduced into hydrocracking zone 20. Additional hydrogen is supplied to hydrocracking zone 20 via lines 26 and 27 in an amount sufficiently low to maintain a continuous liquid phase system therein. A resulting effluent stream is removed from hydrocracking zone 20 via line 17 and is joined with a hydrogen-rich gaseous stream supplied via line 18, and the resulting mixture is conveyed via line 21 and introduced into the product extractor. high pressure 22. A hydrocarbon vapor stream containing boiling point hydrocarbons in a lower range than the feed is removed from the high pressure product extractor 22 via line 23 and recovered. A liquid stream containing unconverted hydrocarbons is removed from the high pressure product extractor via line 16 and joins the feed stream provided by line 1 in the manner described above. The foregoing description and drawings clearly illustrate the

advantages encompassed by the process of the present invention and the benefits to be provided with its use.

Claims (10)

Process for hydrocracking a hydrocarbonaceous feedstock, characterized in that it comprises: (a) introducing a liquid phase stream (1) comprising a hydrocarbonaceous feedload, at least a portion of a liquid phase effluent (16). ) of a hydrocracking zone (13,20) and hydrogen in a hydrogenation zone to produce hydrogen sulfide and ammonia, and to provide a first hydrocarbon stream (7) comprising low sulfur and nitrogen hydrocarbons, said hydrogen present at a concentration sufficiently low to maintain a continuous liquid phase system in said hydrogenation zone; (b) introducing at least a portion of the first hydrocarbon stream (7) comprising low sulfur and nitrogen hydrocarbons into the hydrocracking zone (13,20) with hydrogen present at a hydrogen concentration sufficiently low to maintain a continuous system of liquid phase in the hydrocracking zone; (c) separating a selected hydrocarbon stream from the group consisting of the first hydrocarbon stream (7) comprising low sulfur and nitrogen hydrocarbons, and an effluent (17) from the hydrocracking zone into a separation zone (8, 22) to provide boiling point hydrocracked hydrocarbons in a temperature range less than the hydrocarbon feedstock; (d) recovering the boiling point hydrocracked hydrocarbons in a temperature range lower than that of the hydrocarbon feedstock; and (e) recycling at least a portion of the effluent (16) from the hydrocracking zone to step (a). Process according to Claim 1, characterized in that the hydrocarbon feedstock has a boiling point in the range of 315 ° C (600 ° F) to 565 ° C (1,050 ° F). Process according to claim 1, characterized in that the hydrogenation zone is operated under conditions including a temperature of 204 ° C (400 ° F) to 482 ° C (900 ° F) and a pressure of 3, 5 MPa (500 psig) to 17.3 MPa (2,500 psig). Process according to Claim 1, characterized in that it further comprises recovering unconverted boiling hydrocarbons in the range of the hydrocarbon feed stream into a high pressure product extractor. Process according to Claim 4, characterized in that the ratio of the unconverted boiling point hydrocarbons in the range of the hydrocarbon feed to the hydrocarbon feed load is 1: 5 to 3: 5. Process according to claim 1, characterized in that it further comprises recovering unconverted boiling hydrocarbons in the range of the hydrocarbon feedstock in a fractionation zone. Process according to claim 1, characterized in that the hydrocracking zone is operated under conditions including a temperature of 232 ° C (450 ° F) to 468 ° C (875 ° F) and a pressure of 3, 5 MPa (500 psig) to 17.3 MPa (2,500 psig). Process according to Claim 1, characterized in that it further comprises recovering boiling point unconverted hydrocarbons in the hydrocarbon stream, hydrogen sulfide and ammonia feed stream range and introducing boiling point unconverted hydrocarbons. in the range of hydrocarbon feedstock recovered in the hydrocracking zone (13). Process according to Claim 1, characterized in that it further comprises introducing the first hydrocarbon stream comprising low sulfur and nitrogen hydrocarbons into a hydrocracking zone (20); introducing the effluent from the hydrocracking zone effluent into a separation zone (22) to produce a second hydrocarbon stream (23) containing lower boiling hydrocarbons and a liquid phase hydrocarbon stream (16) comprising unconverted hydrocarbons; and introducing the liquid phase hydrocarbon stream comprising unconverted hydrocarbons in step (a). Process according to Claim 9, characterized in that the separation zone is a high pressure product extractor.