RU2405024C2 - Hydrocracking method - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to a method of hydrocracking hydrocarbon starting material, involving (a) feeding a liquid-phase stream (1) containing hydrocarbon starting material, a product (16) from the hydrocracking zone (13), and hydrogen into a hydrofining zone to obtain hydrogen sulphide and ammonia and formation of a first hydrocarbon stream (7) containing hydrocarbons, characterised by low content of sulphur and nitrogen, wherein said hydrogen is present in concentration sufficiency low for maintaining a liquid-phase continuous system in the said hydrofining zone; (b) feeding at least a portion of the first hydrocarbon stream (7) containing hydrocarbons, characterised by low content of sulphur and nitrogen into the a separation zone (8) for extraction of hydrofining products boiling in a temperature range lower than for the starting material, and obtaining a liquid stream (10) of hydrocarbons containing hydrocarbons which boil in the boiling temperature range of the starting material; (c) feeding the liquid stream (10) of hydrocarbons into the hydrocracking zone (13) in the presence of hydrogen with hydrogen concentration sufficiently low for maintaining a liquid-phase continuous system in the hydrocracking zone; (d) returning the product (16) from the hydrocracking zone (13) to step (a). The invention also relates to another version of cracking hydrocarbon material. ^ EFFECT: obtaining low-boiling hydrocarbons. ^ 15 cl, 1 ex, 2 tbl, 2 dwg

Description

Technical field

The technical field to which this invention relates is the catalytic conversion of hydrocarbons into useful hydrocarbon products. More specifically, the invention relates to catalytic hydrocracking.

State of the art

The present invention relates to hydrocracking of hydrocarbon feedstocks. Refiners often produce the desired products, such as turbine fuel, diesel fuel and other products known as medium distillates, as well as lower boiling hydrocarbon liquids, such as naphtha and gasoline, by hydrocracking hydrocarbon feedstocks derived from crude oil or its heavy fractions. The types of feedstocks most commonly subjected to hydrocracking are gas oils and heavy gas oils extracted from crude oil by distillation. A typical heavy gas oil contains a significant proportion of hydrocarbon components boiling above 371 ° C (700 ° F), with typically at least 50 weight percent boiling above 371 ° C (700 ° F). A typical vacuum gas oil is typically characterized by a boiling range of 315 ° C (600 ° F) to 565 ° C (1050 ° F).

Hydrocracking is usually carried out in a vessel or hydrocracking reaction zone by contacting the gas oil or other feedstock to be processed in contact with a suitable hydrocracking catalyst under elevated temperature and pressure in the presence of hydrogen as a separate phase in a two-phase reaction zone in order to obtain a product containing a specific assortment of hydrocarbon products desired by the refinery. The working conditions and hydrocracking catalysts in the hydrocracking reactor have an effect on the yield of hydrocracking products.

Traditionally, fresh feed for the hydrocracking process is first introduced into the denitrification and desulfurization zone containing hydrogen in the gas phase and is particularly suitable for use in the removal of sulfur and nitrogen-containing contaminants, and then introduced into the hydrocracking zone containing the hydrocracking catalyst, as well as hydrogen in the gas phase. Another method of hydrocracking fresh feedstock is to introduce fresh feedstock and a waste product from the hydrocracking zone to the denitrification and desulfurization zone. The resulting waste product from the hydrocracking zone is separated to obtain the desired hydrocracking products and unreacted feedstock, which is then introduced into the hydrocracking zone. Previously, at least the bulk of the hydrogen present in the reaction zones was contained in the gas phase. This method or technique is usually referred to as a “spray bed catalyst” technique, where the continuous phase is gas rather than liquid.

Despite the use of a wide range of process flow diagrams, operating conditions and catalysts in commercial activities, there is always a need for new hydrocracking methods that can reduce costs, simplify the design, increase the yield of liquid products and improve the quality of products.

US Pat. No. 5,720,872 (Gupta) describes a method for hydrotreating a liquid feedstock in two or more hydrotreating steps, which are carried out in separate reaction vessels, and where each reaction step includes a hydrotreating catalyst bed. The liquid product from the first reaction stage is sent to the low-pressure stripping step and stripped, removing hydrogen sulfide, ammonia and other dissolved gases. After that, the desorbed product stream is directed to the next reaction step according to the technological scheme, the product of which is also subjected to desorption by removing dissolved gases, and sent to the next reaction step according to the technological scheme, until the last reaction stage is reached, the liquid product of which is subjected to desorption to remove dissolved gases , and collected or recycled further for further processing. The process gas stream moves in a direction opposite to that in which the reaction steps for the liquid stream are arranged. Each desorption stage is a separate stage, but all stages fit in the same stripper tank.

US 3,328,290 (Hengstebeck) describes a two-stage process for the hydrocracking of hydrocarbons, in which the feedstock is pre-processed in a first step.

US 5,403,469 (Vauk et al.) Describes a parallel hydrotreating and hydrocracking process. The waste product from the two processes is combined in the same separation tank and separated into steam containing hydrogen and a hydrocarbon-containing liquid. As shown, hydrogen is supplied as part of the feed streams for both hydrocracking and hydrotreating.

US Pat. No. 5,980,729 (Kalnes et al.) Describes a hydrocracking process whereby a hydrocarbon feedstock and a hydrogen-containing hot product from a hydrocracking zone are passed to a denitrification and desulfurization reaction zone to produce hydrogen sulfide and ammonia and thus purify fresh feedstock. The resulting hot uncooled waste product from the denitrification and desulfurization zone is subjected to hydrogen stripping in a stripping zone maintained at substantially the same pressure as the preceding reaction zone using a hydrogen-rich gas stream to produce a steam stream containing hydrogen, hydrocarbon compounds boiling at a temperature lower than the boiling range of fresh feedstock, hydrogen sulfide and ammonia, and a liquid hydrocarbon stream containing unreacted feedstock. This liquid hydrocarbon stream is introduced into the hydrocracking zone to obtain a waste product from the hydrocracking zone, which is then combined with fresh feed as described previously, and then introduced into the denitrification and desulfurization zone.

US Pat. No. 6,106,694 (Kalnes et al.) Describes a hydrocracking process whereby a hydrocarbon feedstock and a hot product from a hydrocracking zone are passed to a denitrification and desulfurization reaction zone to produce hydrogen sulfide and ammonia and thus purify fresh feedstock. The resulting hot uncooled waste product from the denitrification and desulfurization zone is subjected to hydrogen stripping in a stripping zone maintained at substantially the same pressure as the preceding reaction zone using a hydrogen-rich gas stream to produce a steam stream containing hydrogen, hydrocarbon compounds boiling at a temperature lower than the boiling range of fresh feedstock, hydrogen sulfide and ammonia, and a liquid hydrocarbon stream, containing unreacted feedstock. This liquid hydrocarbon stream is then introduced into the hydrocracking zone to produce a waste product, which is then introduced into the denitrification and desulfurization reaction zone as previously described herein.

US 6,123,835 (Ackerson et al.) And US 6,428,686 (Ackerson et al.) Describe a hydrotreatment process where the need for hydrogen circulation through the catalyst is eliminated by mixing hydrogen and the feed as an oil in the presence of a diluent in which the solubility of hydrogen is high in comparison with its solubility in the feedstock. After this, the oil / diluent / hydrogen solution can be fed to a perfect displacement reactor containing a catalyst.

SUMMARY OF THE INVENTION

In one embodiment, the present invention relates to a catalytic hydrocracking method, wherein a liquid phase stream containing a hydrocarbon feedstock, a liquid phase effluent from the hydrocracking zone and hydrogen at a concentration low enough to maintain a liquid phase continuous system is supplied to the hydrotreatment zone to produce hydrogen sulfide and ammonia and the formation of the first hydrocarbon stream containing hydrocarbons, characterized by a low level of sulfur and nitrogen. Hydrocarbons characterized by a low level of sulfur and nitrogen are introduced into the hydrocracking zone at a hydrogen concentration low enough to maintain a liquid-phase continuous system, in order to obtain a waste product from the hydrocracking zone, which contains hydrocarbons having lower boiling limits. In preferred embodiments, the first hydrocarbon stream containing hydrocarbons having a reduced level of sulfur and nitrogen is separated in the stripper of the high pressure product or by conventional distillation to obtain hydrocarbons having a reduced level of sulfur and nitrogen, which are then introduced into the hydrocracking zone .

In a second embodiment, the present invention relates to a catalytic hydrocracking method, wherein a liquid phase stream containing a hydrocarbon feedstock, a liquid phase waste product from the hydrocracking zone and hydrogen at a concentration low enough to maintain a liquid phase continuous system is supplied to the hydrotreatment zone in order to produce hydrogen sulfide and ammonia and the formation of the first hydrocarbon stream containing hydrocarbons, characterized by a low level of sulfur and nitrogen. The first hydrocarbon stream containing hydrocarbons characterized by a low level of sulfur and nitrogen is introduced into the hydrocracking zone at a hydrogen concentration low enough to maintain a liquid-phase continuous system in order to obtain a waste product from the hydrocracking zone. The product from the hydrocracking zone is introduced into a separation zone, which in one embodiment is preferably a high-pressure product stripper to produce a second hydrocarbon stream containing lower boiling hydrocarbons and a liquid phase hydrocarbon stream containing unreacted hydrocarbons that is introduced into the hydrotreatment zone as previously described herein. Hydrocracked hydrocarbons boiling in a temperature range lower than the hydrocarbon feed are recovered.

In conventional hydrotreating operations, a catalyst bed technology is used in jet spraying. This technology makes it necessary to use large quantities of hydrogen in comparison with the amounts of hydrocarbon feedstocks, sometimes exceeding 1685 nm ³ / m ³ (10,000 standard cubic feet / barrel), and requires the use of expensive compression of recycle gas. The use of large quantities of hydrogen in comparison with the quantities of hydrocarbon feedstock during conventional hydrotreating operations turns this option of the operation into a gas-phase continuous system. It has been found that the presence of this large excess of hydrogen is neither economical nor necessary to achieve the desired conversion. Achieving the desired conversion can be achieved with a much smaller amount of hydrogen, and it can be economically and effectively implemented with the amount of hydrogen just sufficient to ensure the presence of a liquid phase continuous system. A liquid-phase continuous system would exist between one extreme case, when the amount of hydrogen is only sufficient to completely saturate the hydrocarbon feedstock, and another extreme case, when hydrogen is added in an amount sufficient to transfer to the gas-phase continuous system. The amount of hydrogen that is added between the two extreme cases is determined by economic considerations. The operation in the presence of a liquid-phase continuous system eliminates the high costs associated with the compressor for gas recycle.

Other embodiments of the present invention include further details, such as types and descriptions of feedstocks, hydrocracking catalysts, hydrotreating catalysts, and preferred operating conditions including temperatures and pressures, all of which are described hereinafter in the following discussion of each of these facets of the invention.

Brief Description of the Drawings

1 and 2 are simplified process diagrams of preferred embodiments of the present invention. Figures 1 and 2 suggest a schematic illustration of the present invention, and not its limitation. Despite the image in the drawings of the process carried out in a mode with a downward flow, this representation is intended to illustrate and does not imply an exception to the process in an upstream mode.

DETAILED DESCRIPTION OF THE INVENTION

The method of the present invention is particularly well suited for use in hydrocracking a hydrocarbon oil containing hydrocarbons and / or other organic materials in order to obtain a product containing hydrocarbons and / or other organic materials having a lower average boiling point and lower average molecular weight . The types of hydrocarbon feedstocks that can be hydrocracked by the method of the invention include all mineral oils and synthetic oils (eg, shale oil, tar sand products, and the like) and fractions thereof. Illustrative types of hydrocarbon feedstocks include those containing components boiling above 288 ° C (550 ° F), such as atmospheric gas oils, vacuum gas oils, deasphalted, vacuum and atmospheric fuel oils, hydrotreated or mild hydrocracked bottoms, coking distillates, straight run solvent distillates, solvent-free oils, pyrolysis oils, high-boiling synthetic oils, recycled gas oils and catalytic cracking distillates. A preferred hydrocracking feedstock is a gas oil or other hydrocarbon fraction containing at least 50% (wt.), And most often at least 75% (wt.), Of its components boiling at a temperature higher than 371 ° C (700 ° F). One of the most preferred types of gas oil feedstocks will contain hydrocarbon components that boil above 288 ° C (550 ° F), with the best results being achieved with feed types containing at least 25 volume percent of components boiling at a temperature in the range of 315 ° C (600 ° F) to 565 ° C (1050 ° F).

The selected hydrocarbon feedstock and hydrogen are introduced into the hydrotreatment reaction zone under the conditions of the hydrotreatment reaction. In addition, the resulting waste product from the hydrocracking reaction zone described hereinafter is also introduced into the hydrotreatment reaction zone. Preferred hydrotreating reaction conditions include a temperature in the range of 204 ° C (400 ° F) to 482 ° C (900 ° F), a pressure ranging from 3.5 MPa (500 lb / ⁱⁿ² (g.)) To 17, 3 MPa (2500 lb / ⁱⁿ² (g.)), a liquid hourly space velocity of the fresh hydrocarbonaceous feedstock from 0.1 hr ^-1 to 10 hr ^-1 with a hydrotreating catalyst or using a combination of hydrotreating catalysts. Hydrogen is introduced into the hydrotreatment reaction zone in an amount only sufficient to maintain a liquid-phase continuous system. This means that, in contrast to the conventional hydrotreating methods that are implemented as a catalyst bed during jet irrigation, in which the gas phase is continuous, the present invention is implemented in a liquid phase continuous system.

The term “hydrotreating” as used herein refers to a method in which a hydrogen-containing process gas absorbed in a liquid hydrocarbon is used in the presence of suitable catalysts that mainly exhibit activity in removing heteroatoms from the hydrocarbon feedstock, such as sulfur and nitrogen. Hydrotreating catalysts suitable for use in the present invention are any conventional conventional hydrotreating catalysts, and they include those that contain at least one Group VIII metal, preferably iron, cobalt and nickel, more preferably cobalt and / or nickel, and at least one Group VI metal, preferably molybdenum and tungsten, on a support material characterized by a high specific surface area, preferably alumina. Other suitable hydrotreating catalysts include zeolite catalysts as well as catalysts containing noble metals, where the noble metal is selected from palladium and platinum. It is within the scope of the present invention to use more than one type of hydrotreating catalyst in the same reaction vessel. The metal from group VIII is usually present in an amount in the range of from 2 to 20 weight percent, preferably from 4 to 12 weight percent. Group VI metal will typically be present in an amount in the range of 1 to 25 weight percent, preferably 2 to 25 weight percent.

In one embodiment of the present invention, the resulting waste product from the hydrotreatment reaction zone is directly introduced into the hydrocracking reaction zone to produce lower boiling hydrocarbons. In another embodiment of the present invention, the resulting waste product is introduced into a separation zone, which is preferably a high-pressure product stripper or conventional fractionation zone, in order to recover lower boiling hydrocarbons and form a hydrocarbon stream containing hydrocarbons boiling over a temperature range boiling fresh feedstock, which is then introduced into the hydrocracking zone. Running at high pressure product stripper is preferably operated at a temperature in the range of 204 ° C (400 ° F) to 482 ° C (900 ° F) and a pressure ranging from 3.5 MPa (500 lb / ⁱⁿ² (g.)) to 17.3 MPa (2500 lb / ⁱⁿ² (g.)).

In a preferred embodiment, in which the product from the hydrotreatment zone is directly introduced into the hydrocracking zone, the product from the hydrocracking reaction zone is preferably introduced into a high pressure stripper, preferably operating at a temperature in the range of 204 ° C. (400 ° F) to 482 ° C. (900 ° F) and a pressure ranging from 3.5 MPa (500 lb / ⁱⁿ² (g.)) to 17.3 MPa (2500 lb / ⁱⁿ² (g.)) in order to obtain a hydrocarbon vapor stream and a liquid hydrocarbon stream containing hydrocarbons boiling in the range of eratur boiling fresh feedstock which is introduced into the hydrotreating zone. In a preferred embodiment, in which the waste product from the hydrotreatment zone is separated between the hydrotreatment zone and the hydrocracking zone, the waste product from the hydrocracking zone is directly introduced into the hydrotreatment zone.

In any case, the feedstock is introduced into the hydrocracking zone together with the added hydrogen in an amount low enough to maintain a liquid-phase continuous system. The hydrocracking zone may include one or more layers of the same or different catalyst. In one embodiment, when middle distillates are the preferred products, amorphous bases or bases having a low zeolite content are used as preferred hydrocracking catalysts in combination with one or more hydrogenation components containing metals from group VIII or group VIB. In yet another embodiment, when gasoline boiling range products are preferred, the hydrocracking zone comprises a catalyst that includes, in general, any crystalline zeolite base of the cracking catalyst onto which an insignificant fraction of the hydrogenating component containing the metal from group VIII is deposited. For inclusion together with the zeolite base from the VIB group, additional hydrogenating components can be selected. The zeolite bases of cracking catalysts are sometimes referred to as molecular sieves in the prior art, and typically consist of silica, alumina, and one or more exchangeable cations, such as sodium, magnesium, calcium, rare earth, etc. In addition, they are characterized by the presence in the crystals of pores having a relatively uniform diameter in the range from 4 to 14 angstroms (10 ^-10 meters). It is preferable to use zeolites having a relatively high silica / alumina molar ratio ranging from 3 to 12. Suitable naturally occurring zeolites include, for example, mordenite, stilbit, heylandite, ferrierite, daciardite, chabazite, eriocyte and fochazit. Suitable synthetic zeolites include, for example, types of crystals B, X, Y, and L, for example synthetic faujasite and mordenite. Preferred zeolites are those characterized by a pore diameter in the crystals in the range of 8 to 12 angstroms (10 ^-10 meters), where the silica / alumina molar ratio is in the range of 4 to 6. A basic example of a zeolite falling in a preferred group is are synthetic molecular sieves Y.

Naturally occurring zeolites typically have a sodium form, an alkaline earth metal form, or mixed forms. Synthetic zeolites are almost always first obtained in sodium form. In any case, when using zeolite as the base of the cracking catalyst, it is preferable that the bulk or all of the monovalent metals of the initial zeolite be ion-exchanged using a polyvalent metal and / or ammonium salt, followed by heating to decompose the ammonium ions associated with the zeolite, receiving in their place hydrogen ions and / or exchange centers, which actually decationize as a result of additional removal of water. Hydrogen or “decationized” Y zeolites of this nature are more specifically described in US Pat. No. 3,130,006.

Mixed zeolites containing a polyvalent metal-hydrogen can be obtained by first conducting an ion exchange using an ammonium salt, then incomplete reverse exchange using a polyvalent metal salt, and then calcining. In some cases, such as in the case of synthetic mordenite, hydrogen forms can be obtained by direct acid treatment of zeolites containing alkali metals. Preferred cracking catalyst bases are those that are depleted in metal cations of at least 10 percent, and preferably at least 20 percent, based on the initial ion exchange capacity. A particularly desirable and stable class of zeolites are those in which hydrogen ions occupy at least 20 percent of the ion exchange capacity.

The active metals used in the preferred hydrocracking catalysts of the present invention as hydrogenation components are metals that belong to group VIII, that is, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum. In addition to these metals, other promoters, including metals from the VIB group, such as molybdenum and tungsten, can also be used in combination with them. The amount of hydrogenation metal in the catalyst can vary widely. Broadly, any amount in the range from 0.05 percent to 30 weight percent can be used. In the case of noble metals, it is usually preferable to use a value in the range from 0.05 to 2 weight percent. A preferred method of introducing a hydrogenation metal is to contact the zeolite-based material in contact with an aqueous solution of a suitable metal compound of the desired metal, wherein the metal is in cationic form. Then, after adding the selected hydrogenating metal or metals, the resulting powdery catalyst is filtered off, dried, granulated, if desired together with added lubricants, binders and the like, and calcined in air at temperatures, for example, 371 ° -648 ° C (700 ° - 1200 ° F), in order to activate the catalyst and decompose ammonium ions. Alternatively, the zeolite component can first be granulated, and then the hydrogenation component is added and activated by calcination. The above catalysts can be used in undiluted form, or the zeolite powder catalyst can be mixed and granulated together with other relatively less active catalysts, diluents or binders such as alumina, silica gel, silica-alumina gels, activated clays, and the like. similar, with fractions in the range of 5 to 90 weight percent. These diluents can be used as such, or they may contain a small proportion of the added hydrogenation metal, such as a metal from group VIB and / or group VIII.

Additional metal-promoted hydrocracking catalysts may also be used in the method of the present invention, which include, for example, aluminophosphate molecular sieves, crystalline chromosilicates and other crystalline silicates. Crystalline chromosilicates are more fully described in US Pat. No. 4,363,718 (Klotz).

Hydrocracking a hydrocarbon feedstock in contact with a hydrocracking catalyst is carried out in the presence of hydrogen concentrations low enough to maintain a liquid phase continuous system, and preferably in a hydrocracking reactor that includes a temperature in the range of 232 ° C (450 ° F) to 468 ° C (875 ° F), a pressure ranging from 3.5 MPa (500 lb / ⁱⁿ² (g.)) to 17.3 MPa (2500 lb / ⁱⁿ² (g.)) and a liquid hourly space velocity (LHSV) ranging from 0.1 to 30 hour ^-1 . In accordance with the present invention, the term “substantial conversion to lower boiling products” is intended to mean the conversion of at least 5 volume percent of fresh feed to products having a lower boiling point than hydrocarbon feed. In a preferred embodiment, the conversion in a single pass in the hydrocracking zone is in the range of 15% to 75%. More preferably, the conversion in one pass is in the range of 20% to 60%. After that, the ratio between the quantities of unreacted hydrocarbons boiling in the boiling range of the hydrocarbon feedstock and the hydrocarbon feedstock is in the range from 1: 5 to 3: 5. The present invention is suitable for use in the manufacture of naphtha, diesel, or any other desirable lower boiling hydrocarbons.

During the conversion or reactions taking place in the hydrotreating and hydrocracking reaction zones, hydrogen is necessarily consumed and must be compensated for using one or more hydrogen input points located in the reaction zones. The amount of hydrogen added in these positions is regulated, ensuring the functioning of the system in the mode of a liquid-phase continuous system. The limiting amount of hydrogen that is added is the amount that causes a transition from a liquid-phase continuous system to a vapor-phase continuous system.

The relative amount of hydrogen required to maintain a liquid-phase continuous system both in the hydrotreating zone and in the hydrocracking zone depends on the specific composition of the hydrocarbon feedstock, the level or conversion to lower boiling hydrocarbon compounds, the composition and amount of lower boiling hydrocarbons, and the temperature and pressure in reaction zone. Those skilled in the art of converting and hydrocracking hydrocarbons can easily determine the proper amount of hydrogen to provide a liquid phase continuous system as soon as all of the above variables are selected.

Detailed Description of Drawings

Turning now to FIG. 1, we can say that through line 1 a feed stream containing vacuum gas oil is introduced into the technological process and mixed with the waste product from the hydrocracking zone transported via line 16. described hereinafter. a hydrogen-rich gas stream, which is also combined with the feed stream, and the resulting mixture is transported through line 3 and introduced into the hydrotreatment zone 4. An additional ha is introduced into hydrotreatment zone 4 through lines 5 and 6 Hydrogen-rich, in order to recover the required hydrogen which is consumed in hydrotreating zone 4. The amount of hydrogen present in hydrotreating zone 4 is sufficiently low to maintain a liquid phase continuous system. The resulting waste product from the hydrotreatment zone 4 is passed through line 7 and introduced into the high-pressure product stripper 8. From the stripper 8 of the high-pressure product, a hydrocarbon vapor stream containing hydrogen sulfide, ammonia and hydrocarbons boiling in a temperature range lower than that of the feedstock is removed and recovered through line 9. From the stripper 8 of the high-pressure product, a liquid hydrocarbon stream containing hydrocarbon compounds boiling in the boiling range of the feedstock, which is combined with the hydrogen-rich stream supplied through line 11, and the resulting mixture through line 12, are removed through line 10 additional hydrogen is transported and introduced into the hydrocracking zone 13. Additional hydrogen is supplied through the lines 14 and 15 to the hydrocracking zone 13. Hydrogen supplied to the hydrocracking zone 13 is present in an amount low enough to maintain a liquid-phase continuous system. From the hydrocracking zone 13, a resulting waste product from the hydrocracking zone is removed via line 16, which is combined with fresh feed through line 1, as previously described herein.

Turning now to FIG. 2, it can be said that a feed stream containing vacuum gas oil is introduced into the process through line 1 and mixed with the waste product from the hydrocracking zone transported via line 16. described further in this document. hydrogen gas stream, which is also combined with the feed stream, and the resulting mixture through line 3 is transported and introduced into the hydrotreatment zone 4. In the hydrotreatment zone 4 through additional lines 5 and 6 od. The total hydrogen supply to the hydrotreatment zone 4 is low enough to maintain a liquid-phase continuous system. The resulting waste product stream from the hydrotreatment zone 4 is removed through line 7 and combined with the hydrogen-rich gas stream supplied through line 24 in an amount low enough to maintain a liquid phase continuous system, and the resulting mixture through the line 25 is transported and introduced into the zone hydrocracking 20. Through lines 26 and 27, additional hydrogen is supplied to the hydrocracking zone 20 in an amount low enough to maintain a liquid-phase continuous system in it. The resulting waste product stream is removed from the hydrocracking zone 20 via line 17, which is combined with the hydrogen-rich gas stream supplied through line 18, and the resulting mixture is transported through line 21 and introduced to the high pressure product stripper 22. From the stripper 22 of the high-pressure product, a hydrocarbon vapor stream containing hydrocarbons boiling in a temperature range lower than that of the feedstock is removed and recovered through line 23. A liquid hydrocarbon stream containing unreacted hydrocarbons is removed from the high-pressure product stripper via line 16, which is combined with the feed stream fed through line 1, as previously described herein.

The foregoing description and drawings clearly illustrate the advantages included in the method of the present invention and the benefits made possible by its use.

Example of consumption and amount of hydrogen used

Tests were conducted on two pilot plants.

Tests at one installation were conducted under traditional conditions with a catalyst bed during jet irrigation with a large amount of added hydrogen, while at another installation a very small amount of hydrogen was added in order to simulate the conditions that exist in a liquid-phase continuous system.

A vacuum gas oil was hydrotreated to remove sulfur before the fluid catalytic cracking process. The properties of the raw materials are presented in table 1.

Table 1 Density in degrees ANI 21.03 Specific gravity, g / cm ³ 0.9277 Sulfur, wt.% 2,36 Nitrogen, weight. parts per million 12.06 Hydrogen, wt.% 12.06 Distillation, D-2887 0.5 wt.% 575 ° F 5 660 10 695 twenty 741 thirty 775 40 803 fifty 829 60 855 70 885 80 918 90 965 95 992 99.5 1065

The conditions of the method and the results are presented in table 2.

table 2 Method conditions Execution method Traditional Liquid phase continuous system Pressure lb / in ² (s) 1260 1259 Temperature ° F 706 740 Volumetric speed, h ^-1 1.00 1,02 H2 / raw material (Art. Foot ³ / barrel) 3175 603 Product Properties and Hydrogen Consumption Sulfur, weight. parts per million 425 477 Hydrogen, wt.% 13.04 12.87 The consumption of hydrogen, (st. Ft ³ / barrel) 617 498

From table 2 it is seen that when implementing the method in a liquid-phase continuous process reactor, less hydrogen is required than in a traditional reactor to achieve almost the same level of desulfurization (at the same space velocities and pressures), although a slightly higher temperature is required.

Claims (15)

1. The method of hydrocracking hydrocarbon feedstock, which includes:
(a) introducing a liquid phase stream (1) containing a hydrocarbon feedstock, a product (16) leaving the hydrocracking zone (13), and hydrogen into a hydrotreating zone to produce hydrogen sulfide and ammonia and forming a first hydrocarbon stream (7) containing hydrocarbons, characterized by a low level of sulfur and nitrogen, while said hydrogen is present in a concentration low enough to maintain a liquid-phase continuous system in said hydrotreatment zone;
(b) introducing at least a portion of the first hydrocarbon stream (7) containing hydrocarbons having a low level of sulfur and nitrogen into the separation zone (8) to recover hydrotreating products boiling in a temperature range lower than that of the feedstock and obtaining a liquid hydrocarbon stream (10) containing hydrocarbons boiling in the range of boiling temperatures of the feedstock;
(c) introducing a liquid stream (10) of hydrocarbons into the hydrocracking zone (13) in the presence of hydrogen at a hydrogen concentration low enough to maintain a liquid-phase continuous system in the hydrocracking zone;
(d) returning the waste product (16) from the hydrocracking zone (13) for recycling to step (a). 2. The method according to claim 1, where the hydrocarbon feedstock boils at a temperature of from 315 ° C (600 ° F) to 565 ° C (1050 ° F). 3. The method of claim 1, wherein the hydrotreating zone is operated at conditions including a temperature of 204 ° C (400 ° F) to 482 ° C (900 ° F) and a pressure of 3.5 MPa (500 lb / ⁱⁿ² (g .)) to 17.3 MPa (2500 lb / ⁱⁿ² (g.)). 4. The method according to claim 1, which includes the extraction of unreacted hydrocarbons boiling in the boiling range of the hydrocarbon feedstock in the separation zone, made in the form of a stripper product operating at high pressure. 5. The method according to claim 4, where the ratio between the amounts of unreacted hydrocarbons boiling in the boiling range of the hydrocarbon feedstock and the hydrocarbon feedstock is from 1: 5 to 3: 5. 6. The method according to claim 1, which includes the extraction of unreacted hydrocarbons boiling in the boiling range of the hydrocarbon feedstock in the separation zone, made in the form of a fractionation zone. 7. The method of claim 1, wherein the hydrocracking zone is operated at conditions including a temperature of 232 ° C (450 ° F) to 468 ° C (875 ° F) and a pressure of 3.5 MPa (500 lb / ⁱⁿ² (g .)) to 17.3 MPa (2500 lb / ⁱⁿ² (g.)). 8. The method according to claim 1, which includes the extraction of unreacted hydrocarbons boiling in the boiling range of the hydrocarbon feedstock, hydrogen sulfide and ammonia from the hydrocarbon stream and introducing the extracted unreacted hydrocarbons boiling in the boiling range of the hydrocarbon feedstock to the hydrocracking zone (13) . 9. A method of hydrocracking a hydrocarbon feedstock, which comprises:
(a) introducing a liquid phase stream (1) containing a hydrocarbon feedstock, a liquid phase effluent (16) from a hydrocracking zone (20) and hydrogen into a hydrotreating zone to produce hydrogen sulfide and ammonia and forming a first hydrocarbon stream (7) containing hydrocarbons characterized by low levels of sulfur and nitrogen, while said hydrogen is present in a concentration low enough to maintain a liquid-phase continuous system in said hydrotreatment zone;
(b) introducing at least a portion of the first hydrocarbon stream (7) containing hydrocarbons having a low sulfur and nitrogen content into the hydrocracking zone (20) in the presence of hydrogen at a hydrogen concentration low enough to keep the liquid phase continuous in the hydrocracking zone systems;
(c) introducing the waste product (17) from the hydrocracking zone into the separation zone (22) to separate the hydrocracked hydrocarbons boiling in a temperature range lower than that of a hydrocarbon feedstock from hydrocarbons boiling in a temperature range higher than that of a hydrocarbon feedstock;
(d) recovering a steam stream (23) of hydrocracked hydrocarbons boiling in a temperature range lower than that of a hydrocarbon feedstock; and
(e) returning at least a portion of the effluent liquid product (16) containing hydrocarbons whose boiling point is higher than the boiling point of the feedstock from the hydrocracking zone for recycling to step (a). 10. The method according to claim 9, where the hydrocarbon feedstock boils at a temperature of from 315 ° C (600 ° F) to 565 ° C (1050 ° F). 11. The method of claim 9, wherein the hydrotreating zone is operated at conditions including a temperature of 204 ° C (400 ° F) to 482 ° C (900 ° F) and a pressure of 3.5 MPa (500 lb / ⁱⁿ² (g .)) to 17.3 MPa (2500 lb / ⁱⁿ² (g.)). 12. The method according to claim 9, which further includes the extraction of unreacted hydrocarbons boiling in the boiling range of the hydrocarbon feedstock in the separation zone, made in the form of a stripper product operating at high pressure. 13. The method according to item 12, where the ratio between the amounts of unreacted hydrocarbons boiling in the boiling range of the hydrocarbon feedstock and the hydrocarbon feedstock is from 1: 5 to 3: 5. 14. The method according to claim 9, which further includes recovering unreacted hydrocarbons boiling in the boiling range of the hydrocarbon feedstock in a separation zone made in the form of a fractionation zone. 15. The method of claim 9, wherein the hydrocracking zone is operated at conditions including a temperature of 232 ° C (450 ° F) to 468 ° C (875 ° F) and a pressure of 3.5 MPa (500 lb / ⁱⁿ² (g .)) to 17.3 MPa (2500 lb / ⁱⁿ² (g.)).

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