KR20030000785A - Simultaneous hydroprocessing of two feedstocks - Google Patents

Abstract

PURPOSE: Provided is a catalytic hydrocracking process, in which two feedstocks are simultaneously hydrogenated to increase yield and quality of liquefied product. CONSTITUTION: The process comprises the steps of (i) passing a first hydrocarbon feedstock and hydrogen through hydrocracking area(3) containing hydrocracking catalyst, and then recovering a discharge from the hydrocracking area(3), wherein the hydrocracking area(3) works at temperature of 204-482 deg.C, and pressure of 3.44-17.2 mPa, and hourly space velocity of liquid of 0.1-15/hr; (ii) directly passing the discharge through high temperature and high pressure stripper(5) which forms a first vapor stream and a first liquid stream, by using a high temperature stripping gas enriched in hydrogen; (iii) passing a second hydrocarbon feedstock having boiling temperature lower than that of the first hydrocarbon feed stock, through the top of the stripper; (iv) passing a part of the first vapor stream recovered in the step(ii), through separate container containing post-treatment hydrogenation area(8), so as to saturate an aromatic compound; (v) condensing a part of the discharge emitted from the post-treatment hydrogenation area(8), to form a second liquid stream comprising hydrocarbon compound having boiling point lower than that of the first hydrocarbon feedstock, and a second vapor stream comprising hydrogen and hydrogen sulfide; and (vi) recycling at least a part of the second vapor stream to hydrocracking area(3).

Description

Simultaneous Hydroprocessing of Two Feedstocks {SIMULTANEOUS HYDROPROCESSING OF TWO FEEDSTOCKS}

The present invention belongs to the art of hydroprocessing two hydrocarbon feedstocks simultaneously. For example, a refinery can hydrolyze a hydrocarbon feedstock from crude oil to produce desirable products, such as turbine fuels, diesel fuels, etc., known as intermediate distillates, as well as lower boiling hydrocarbon liquids such as naphtha and gasoline. Frequent The feedstocks most often hydrocracked are light and heavy oils recovered from crude oil by distillation. Typical heavy oils contain a significant portion of hydrocarbon components having a boiling point above 371 ° C., which typically contains at least 50% by weight. The boiling point of a typical vacuum gas oil is usually in the range between 315 ° C and 565 ° C.

Hydrocracking is carried out to provide a suitable hydrocracking catalyst for diesel or other feedstock to be treated in the presence of hydrogen under high temperature and pressure conditions in a hydrocracking reaction vessel or reaction zone to produce a product comprising a hydrocarbon product in a distribution required for the refinery. It is common to make it by contact with. The operating conditions in the hydrocracking reaction apparatus and the hydrocracking catalyst affect the yield of the product hydrocracked.

U.S. Patent 5,720,872 discloses a process for hydroprocessing a liquid feedstock in two or more hydroprocessing stages, each of which is located in a separate reaction vessel, each reaction stage containing a hydroprocessing catalyst bed. Doing. The liquid product from the first reaction stage is sent to a low pressure stripping stage to remove hydrogen sulfide, ammonia and other dissolved gases. The stream of stripped product is then sent to the next downstream reaction stage where the product from the downstream reaction stage is also removed from the dissolved gas and transferred to the next downstream reaction stage to reach the final reaction stage. The liquid product of this final reaction stage is either collected after the dissolved gas is stripped off or passed for subsequent treatment. The flow of process gas is in the direction opposite the direction in which the reaction stage is disposed relative to the flow of liquid. Each stripping stage is a separate stage, but all are housed in the same stripping vessel.

International Publication No. WO 97/38066 (PCT / US97 / 04270) discloses a process for reverse staging in a hydrotreating reaction system.

U.S. Patent No. 3,328,290 discloses a two-stage process for hydrocracking hydrocarbons in which the feedstock is pretreated in the first stage.

U.S. Patent 5,114,562 discloses a process employing two serially located reaction zones in which a stream of middle distillate petroleum is hydrotreated to produce a product containing less sulfur and aromatics. Effluent from the first reaction zone (desulfurization zone) is cooled and introduced into the hydrogen stripping zone, where hydrogen sulfide is removed from the top together with a small amount of hydrocarbons that were in the vapor while present at the top of the zone. The bottom stream from the stripping zone is reheated and then introduced into a second reaction zone (aromatic compound saturation zone) containing sulfur sensitive noble metal hydrogenation catalyst. As it goes from the first reaction zone to the second reaction zone, the operating pressure increases and the temperature decreases. The desulfurization conditions employed are relatively relaxed because only a very limited degree of decomposition is needed. It is not desirable at all to cause a significant amount of decomposition in the second reaction zone. It is highly desirable to minimize the content of heavy product distillate hydrocarbons, such as diesel fuel, in the stripping zone in the gas phase.

Although various process flow schemes and operating conditions and catalysts have been used in commercial activities, there is always a need for new hydrocracking methods that are less expensive and provide better yields and quality of liquid products. It is well known that catalytic hydrocracking zones can improve product selectivity at lower conversions per pass (60% to 90% of fresh feedstock is converted). Previously, however, operating at conversions per pass below 60% had little to no advantage or only reduced revenue. Low conversion per pass is generally more expensive, but the present invention significantly improves the economic benefits of low conversion per pass processes and shows unexpected advantages.

1 is a schematic process flow diagram of a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

3: hydrocracking zone

5: high pressure product stripper

8: aftertreatment zone

10, 27: heat exchanger

12: high pressure separator

14: low pressure separator

18: amine scrubber

22: compressor

The present invention provides a catalytic hydrocracking process wherein the two feedstocks are hydrotreated simultaneously to improve the yield and quality of the liquid product. The process of the present invention provides an advantage in yield associated with low conversion per pass operation without compromising unit economics. In addition, the use of the process of the present invention can achieve a reduction in capital cost.

In the present invention, the first hydrocarbon feedstock and hydrogen are sent to a hydrocracking reaction zone to produce a stream comprising a hydrocarbon compound having a low boiling point, which is in turn sent to a high temperature, high pressure stripper, which stripper A stream containing a hydrocarbon compound and hydrogen boiling at a lower temperature than the first hydrocarbon feedstock using a hydrogen-rich hot stripping gas, and a hydrocarbon compound boiling in the range of the first hydrocarbon feedstock. Create a flow of liquid. A second hydrocarbon feedstock having a boiling point lower than the first hydrocarbon feedstock is transferred into the upper end of the stripping device to serve as reflux. A stream of steam comprising hydrogen and hydrocarbon compounds boiling at a lower temperature than the first hydrocarbon feedstock is introduced into a post treatment hydrogenation reaction zone comprising a separate vessel that saturates at least some of the aromatic compounds contained therein. At least a portion of the second hydrocarbon feedstock is evaporated in the stripper and sent to the post-treatment hydrogenation zone to saturate the aromatics to improve the quality of hydrocarbon emissions from the post-treatment hydrogenation zone. At least a portion of the effluent from the post treatment hydrogenation reaction zone is condensed to produce a second liquid stream comprising a hydrocarbon compound boiling at a lower temperature than the first hydrocarbon feedstock and a second vapor stream comprising hydrogen and hydrogen sulfide. do. According to one preferred embodiment of the invention, at least a portion of the hydrogen sulfide is removed therefrom before the second steam stream is recycled to the hydrocracking reaction zone. The separate post-treatment hydrogenation zone is maintained in a separate vessel because the second hydrocarbon feedstock requires a temperature higher than the temperature appropriate for the post-treatment hydrogenation zone at the top of the high temperature, high pressure stripping unit. This is because

According to one embodiment of the present invention, the present invention relates to a method of simultaneously hydrotreating two feedstocks having different boiling ranges, which comprises (a) a temperature of 204 ° C. to 482 ° C., 3.44 mPa to 17.2 mPa. And a first hydrocarbon feedstock and hydrogen through a hydrocracking zone containing a hydrocracking catalyst, operating at a pressure of and a liquid hourly space velocity (LHSV) of 0.1 ^hr-1 to 15 ^hr-1 . Recovering the hydrocracking zone effluent therefrom, and (b) a first vapor stream comprising hydrogen, hydrogen sulfide, and a hydrocarbon compound boiling at a lower temperature than the first hydrocarbon feedstock, using a hot stripped gas rich in hydrogen; And hydrogenation with a high temperature, high pressure stripper to produce a first liquid stream comprising a hydrocarbon compound boiling in the range of the first hydrocarbon feedstock. (C) passing a second hydrocarbon feedstock having a boiling temperature range lower than the first hydrocarbon feedstock into the upper end of the stripper to serve as reflux, and (d) (B) passing at least a portion of the first vapor stream recovered in step (b) to a post-treatment hydrogenation zone contained in a separate vessel to saturate the aromatic compound, and (e) the post-treatment hydrogenation zone Condensing at least a portion of the resulting effluent from the second liquid stream comprising a hydrocarbon compound boiling at a lower temperature than the first hydrocarbon feedstock and a second vapor stream comprising hydrogen and hydrogen sulfide, (f) recycling at least a portion of the second vapor stream to the hydrocracking zone.

According to another embodiment of the present invention, at least a portion of the second liquid stream is recycled to the hydrocracking zone.

The present invention is particularly useful for hydrotreating two feedstocks to increase the yield of liquid products and to reduce production costs. The feedstock has a low average boiling point, improved product properties such as cetane number and smoke point, hydrocarbons and / or other organics to produce products containing hydrocarbons and / or other organic substances with reduced pollutants such as sulfur and nitrogen. Contains substances. Hydrocarbon feedstocks that can be hydrotreated according to the process of the present invention include all mineral and synthetic oils (eg shale oil, tar sand products, etc.) and their fractions. Hydrocarbon feedstocks boiling at higher temperatures include atmospheric gas oil, vacuum gas oil, asphalted and vacuum residues and atmospheric residues, hydrogenated residual oils, coker distillates, straight run distillates. Such as those containing boiling components at temperatures above 288 ° C., such as pyrolysis induced oils, high boiling point synthetic oils and catalytic cracker distillates. Preferred hydrocracking feedstocks contain at least 50 wt%, most typically at least 75 wt% of boiling components at temperatures above the end point of the required product (typically in the range of 193 ° C to 215 ° C for heavy gasoline). Diesel or other hydrocarbon fractions. One of the most preferred diesel fuel feedstocks includes hydrocarbon components that boil at temperatures above 288 ° C., which results in the best results when it contains more than 25% by volume of components that boil between 315 ° C. and 538 ° C. Also included are petroleum distillates in which at least 90% of the components boil in the range of 149 ° C to 426 ° C.

The first selected feedstock is first introduced into the hydrocracking reaction zone under hydrogenation reaction conditions. Preferred hydrocracking reaction conditions include a liquid hourly space velocity of 0.1 ^hr-1 to 10 ^{hr-1 in} the presence of a hydrocracking catalyst with a temperature of 204 ° C. to 482 ° C. and a pressure of 3.44 mPa to 17.2 mPa. Included.

The hydrocracking zone may comprise one or more identical or different catalyst beds. In one embodiment, where the preferred product is an intermediate distillate, the preferred hydrocracking catalyst uses an amorphous base or a low level of zeolite base combined with one or more Group VIII or Group VIB metal hydrogenation components. According to another embodiment, in the case where the preferred product is in the gasoline boiling range, the hydrocracking zone comprises a general catalyst comprising any crystalline zeolite cracking base to which a Group VIII metal hydrogenation component is attached in small proportions. Another hydrogenation component can be selected from the group VIB for inclusion in the zeolite base. Zeolite decomposition bases, often referred to in the art as molecular sieves, typically consist of silica and alumina and one or more compatible cations such as sodium, magnesium, calcium, rare earth metals, and the like. In addition, the zeolite decomposition base is characterized in that the crystal pores have a relatively uniform diameter between 4 kPa and 14 kPa. Preference is given to using zeolites having a relatively high silica / alumina molar ratio between 3 and 12. Suitable zeolites found in nature include, for example, mordenite, stilbite, hulandite, ferrierite, dachiardite, chaperzite, erionite, and faujasite. Examples of suitable synthetic zeolites are B, X, Y and L crystalline forms such as synthetic faujasite and mordenite. Preferred zeolites are those having a crystal pore diameter of 8-12 kPa and silica / alumina mole ratio of 4-6. Representative examples of zeolites in the preferred range include synthetic Y molecular sieves.

Naturally occurring zeolites are commonly found in sodium, alkaline earth metal or mixed form. Synthetic zeolites are almost always prepared in sodium form first. In all cases, for use as a decomposition base, most or all of the original zeolite monovalent metal is ion-exchanged with polyvalent metals and / or ammonium salts after heating to decompose the ammonium ions bound to the zeolites, It is desirable to leave exchange sites and / or hydrogen ions with almost no cations removed by further removal. “Cation-free” Y zeolites or hydrogens with this property are described in more detail in 3,130,006.

Mixed polyvalent metal-hydrogen zeolites can be prepared by first ion exchanging with ammonium salts, followed by partial back exchange with polyvalent metal salts and then firing. In some cases, the hydrogen form can be prepared by direct acid treatment of the alkali metal zeolite as in the case of synthetic mordenite. Preferred decomposition bases are those which lack at least 10%, preferably at least 20% metal cations based on the original ion exchange capacity. Particularly preferred and stable grades of zeolites are those in which at least 20% of the ion exchange capacity is met by hydrogen ions.

The active metals used in the preferred hydrocracking catalysts of the present invention as hydrogenation components are Group VIII metals, ie iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum. In addition to these metals, other accelerators can be used together, including metals of the VIB group, such as molybdenum and tungsten. The amount of metal hydride in the catalyst can vary over a wide range. Broadly speaking, any amount between 0.05% and 30% by weight can be used. For precious metals it is usually preferred to use 0.05 to 2% by weight. A preferred method of incorporating a metal hydride is to contact the zeolite substrate with an aqueous solution of the appropriate compound of the required metal, which is present in cation form. After addition of the selected metal hydride, the resulting catalyst powder is filtered and dried and, if necessary, pelletized with addition of lubricants, binders, etc., to activate the catalyst and decompose ammonium ions, for example 371 ° C.- It is calcined in air at a temperature of 648 ° C. As an alternative, the zeolite component may be pelletized first, followed by the addition of a hydrogenation component and activated by firing. The catalysts described above can be used in undiluted form, or the powdered zeolite catalyst can be used in combination with other relatively less active catalysts, diluents or binders such as alumina, silica gel, silica-alumina hybrid gels, activated clays, etc. at 5 and 90% by weight. Can be mixed and hybridized at a ratio between. As such, these diluents may be used, or a small proportion of added hydrogenated metals such as Group VIB and / or Group VIII metals may be included.

For example, additional metal catalyzed hydrocracking catalysts including aluminum phosphate molecular sieves, crystalline chromosilicates and other crystalline silicates can also be used in the process of the present invention. Crystalline chromosilicates are described in more detail in US Pat. No. 4,363,718.

Hydrocracking of the hydrocarbon feedstock in contact with the hydrocracking catalyst takes place in the presence of hydrogen, at a temperature of 232 ° C. to 468 ° C., a pressure of 3.44 mPa to 20.7 mPa, and a liquid hourly space velocity of 0.1 to 30 ^{hr −1} . And 337 normal m ³ / m ³ to 4200 normal m ³ / m ³ . According to the present invention, the term "substantial conversion to a low boiling product" means at least 10% by volume conversion of fresh feedstock. The conversion per pass of the hydrocracking zone is preferably in the range of 10% to 50%, more preferably in the range of 20% to 40%.

The resulting discharge from the hydrocracking reaction zone is conveyed without intentional heat exchange (not cooled), introduced into a hot, high pressure stripping zone which is maintained at approximately the same pressure as the hydrocracking reaction zone, and then hydrogen-rich in a countercurrent manner. A first gaseous hydrocarbon stream comprising a hydrocarbon compound, hydrogen sulfide and ammonia stripped by a gas stream and boiling at a temperature below 371 ° C., and a first liquid hydrocarbon stream comprising a hydrocarbon compound boiling at a temperature above 371 ° C. Create The stripping zone is preferably maintained at a temperature range of 232 ° C to 468 ° C. Emissions from the hydrocracking reaction zone are hardly cooled and only drop in temperature due to unavoidable heat losses during transfer from the reaction zone to the stripping zone. Cooling of the discharge of the hydrocracking reaction zone is preferably lower than 842 ° C, more preferably lower than 56 ° C. Maintaining the pressure in the stripping zone at about the same pressure as the hydrocracking reaction zone means that any pressure difference is due to the pressure drop required to allow the discharge stream to flow from the reaction zone to the stripping zone. The pressure drop is preferably less than 1.03 mPa, more preferably less than 0.69 mPa. The stream of hydrogen-rich gas is preferably fed to the stripping zone in an amount greater than 5% by weight of the hydrocarbon feedstock. The second feedstock is introduced into the upper end of the hot and high pressure stripper to serve as reflux and further processed in accordance with the present invention.

At least a portion of the first liquid hydrocarbon stream comprising hydrocarbon compounds boiling at temperatures above 371 ° C. recovered from the stripping zone is recycled to the hydrocracking reaction zone with the addition of hydrogen according to a preferred embodiment of the present invention.

The resulting first gaseous hydrocarbon stream comprising hydrocarbon compound, hydrogen, hydrogen sulfide and ammonia boiling at a temperature lower than 371 ° C. obtained from the stripping zone is introduced into a separate vessel containing a post-treatment hydrocarbon reaction zone to provide at least a portion of the aromatic compound. Hydrogenation improves the quality of the middle distillate, in particular jet fuel. A portion of the first gaseous hydrocarbon stream comprises at least a portion of the second feedstock. The mode of operation of the post-treatment hydrogenation reaction zone can be in a down flow, up flow or radial flow mode, and any known hydrogenation catalyst can be used.

Downflow is preferred for the reactor because intermediate heat exchange is often required between the hot and high pressure stripper and the post-treatment hydrogenation zone for the higher temperatures required for the second feedstock. Cooling of the first gas stream may produce mixed phase conditions that are most suitable for the downflow operation. Effluent from the workup hydrogenation reaction zone is cooled to a temperature in the range of 4.4 ° C. to 60 ° C. and at least partially condensed to produce a second liquid hydrocarbon stream, which is recovered and fractionated to produce the required hydrocarbon product stream. A portion of the second liquid hydrocarbon stream can be recycled to the top of the hot and high pressure stripper with the second feedstock. Condensed second liquid hydrocarbon flow chart to produce a second hydrogen-rich gas stream, the second hydrogen-rich gas stream is divided into two, at least a portion of the hydrogen introduced and added into the hydrocracking zone as described above; Provide at least a portion of the first hydrogen-rich gas stream introduced into the stripping zone. Fresh supplemental hydrogen may be introduced into the process at any suitable and convenient location, but is preferably introduced into the stripping zone. Before the second hydrogen-rich gas stream is introduced into the hydrocracking zone, it is preferred that at least a substantial portion of the hydrogen sulfide, for example at least 90% by weight, be removed and recovered by known conventional methods. According to a preferred embodiment of the present invention, the hydrogen-rich gas stream introduced into the hydrocracking zone comprises less than 50 wppm hydrogen sulfide.

According to the invention, the second feedstock comprises hydrocarbons and / or other organic substances, the boiling range of the second feedstock being equal to, or at least partially, the boiling range of the first feedstock. Lower than The second feedstock is preferably boiled in the range of 149 ° C to 382 ° C. The second feedstock is introduced into the upper end of the hot and high pressure stripper to serve as reflux. Depending on the boiling range of the second feedstock and the operating conditions of the stripper, at least a portion may be evaporated and transferred directly to the aftertreatment hydrogenation zone, where heteroatoms including sulfur and nitrogen are converted to hydrocarbons to convert hydrogen sulfide and ammonia. To saturate the aromatic compound. The post treatment hydrogenation zone produces a hydrocarbon stream with improved product properties.

In the drawings, which are not intended to limit the invention but merely to illustrate it, the process of the present invention is shown by way of schematic flow diagrams, with details such as pumps, appliances, heat exchange circuits and heat recovery circuits, compressors and similar devices relating thereto. It is omitted because it is not essential to the understanding of the technology. The use of many such devices is within the scope of those skilled in the art.

A new feedstock of vacuum gas oil is introduced into the process via line (1), so that the recycled liquid hydrocarbons fed through line (6) and the hydrogen-rich recycle gas stream fed through line (29) and Are mixed. The resulting mixture is introduced into the hydrocracking zone 3 via line 2. The resulting hydrocracked effluent is removed from the hydrocracking zone 3 via conduit 4 and introduced directly into the high pressure product stripper 5. The liquid hydrocarbon stream is removed from the high pressure product stripper (5) via line (6), with some recycled through line (6) to hydrocracking zone (3). Another portion of the bottom hydrocarbon liquid from the high pressure product stripper 5 is removed and recovered by lines 6 and 25. A second new feedstock containing hydrocarbons in the diesel boiling range is introduced via line 24 to the top of the high pressure product stripper 5 to serve as reflux and to be processed in the unit. A vapor stream comprising at least a majority of the second feedstock introduced via line 24 and the hydrocracked hydrocarbon compound is removed from the high pressure product stripper 5 through line 7 and into the aftertreatment zone 8. Is introduced. The resulting hydrotreated gaseous hydrocarbon stream is removed from the aftertreatment zone 8 via line 9 and mixed with the flow of wash water introduced through line 33 and the resulting mixture is introduced into heat exchanger 10. do. The resulting cooled and partially condensed flow is removed from the heat exchanger 10 through line 11 and introduced into the high pressure separator 12. The flow of water used is removed from the high pressure separator 12 via line 34. Liquid hydrocarbon stream is removed from the high pressure separator 12 via line 13 and introduced into the low pressure separator 14. The gaseous hydrocarbon stream, which is usually gaseous, is removed from the low pressure separator 14 through conduit 15 and recovered. Liquid hydrocarbon product stream is removed from the low pressure separator 14 through conduit 16 and recovered. A stream of hydrogen-rich gas, including hydrogen sulfide, is removed from the high pressure separator 12 through line 17 and introduced into amine scrubber 18. The amine-lean solution is introduced into line amine scrubber 18 through line 35 and the amine-rich solution is removed therefrom. A hydrogen rich gas stream comprising reduced hydrogen sulfide is removed from the amine scrubber 18 through line 19 and mixed with the hydrogen component stream supplied through line 20. The resulting mixture of hydrogen-rich gas is passed through line 21 and compressed in compressor 22. Some of the compressed hydrogen-rich gas is removed from the compressor 22 and carried through lines 23 and 29 to provide a hydrogen-rich recycle gas stream as described above. Another portion of the compressed hydrogen-rich gas is removed from compressor 22 via lines 23 and 26 and introduced into heat exchanger 27. The flow of heated hydrogen-rich gas is removed from the heat exchanger 27 through line 28 and introduced into the bottom of the high pressure product stripper 5 to serve as stripping gas and reactant in the aftertreatment reaction zone 8. Do it.

Example

91.4 into a hydrocracking zone operating a vacuum diesel fuel feedstock having the characteristics shown in Table 1 operating at conditions including a pressure of 11.0 mPa, a temperature of 399 ° C. and a hydrogen circulation rate of 1348 nm ³ / m ³ and including a hydrocracking catalyst. Introduced at a flow rate of m ³ / hr. The discharge from the hydrocracking zone is introduced into a high temperature, high pressure stripper operating at a pressure of 10.7 mPa and a temperature of 399 ° C without cooling. A diesel boiling range feedstock with the characteristics shown in Table 1 is introduced into the upper end of the hot and high pressure product stripper at a flow rate of 58.9 m ³ / hr to serve as reflux and to elevate the grade. On the basis of the composite feedstock, a hot hydrogen-rich stripping gas is introduced into the bottom of the stripper at a flow rate of 1264 nm ³ / m ³ . A vapor stream comprising at least a majority of the diesel feedstock and the hydrocracked hydrocarbon compound is removed from the high pressure product stripper, comprising a hydrogenation catalyst selected according to the ability to saturate the aromatic hydrocarbon compound and having a pressure of 10.7 mPa and a temperature of 349 ° C. It is introduced into the aftertreatment zone operating under conditions including. The resulting hydrotreated gaseous hydrocarbon stream is removed from the workup zone, mixed with the wash water and cooled. The resulting cooled, partially condensed stream is separated to recover the used water stream, liquid hydrocarbon stream and hydrogen rich gas stream. This recovered liquid hydrocarbon stream is stabilized and separated to obtain a diesel product having a specific gravity of 0.849 and a cetane index of 50 at 15 ° C. at a flow rate of 96.7 m ³ / hr and a naphtha product at a flow rate of 17.2 m ³ / hr. The unconverted hydrocarbon stream is removed from the bottom of the high pressure product stripper at a flow rate of 45.7 m ³ / hr and recycled to the hydrocracking zone. Another stream having a specific gravity of 0.886 at 15 ° C. is removed from the bottom of the high pressure product stripper at a flow rate of 46.4 m ³ / hr and charged into the fluid catalytic cracking zone or otherwise used.

Feedstock Analysis Via vacuum diesel Specific gravity @ 60。F 0.940 0.8817 Distillation, ° C IBP 333 214 10% 347 262 50% 399 279 90% 498 304 EP 569 352 Sulfur, wt% 1.31 0.005 Nitrogen, wppm 386 <100 Cetane index - 40

Table 2 shows a comparison of the yield by the process of the present invention and the yield by the prior art flow method.

Yield comparison Prior art The present invention Naphtha, m ³ / hr 21.8 17.2 Diesel, m ³ / hr 91.4 96.7 FCC feedstock, m ³ / hr 46.4 46.4 sum 159.6 160.3

Table 3 shows a comparison of the diesel quality according to the process of the present invention and the diesel quality according to the prior art flow method.

Diesel quality comparison Diesel characteristics Prior art The present invention Specific gravity, 15 ° C 0.863 0.850 Boiling Range, ° C 196-360 196-360 Cetane index 45 50

The data shown in Tables 2 and 3 show the advantages of the present invention with higher selectivity and cetane index of diesel products.

The foregoing description, drawings and exemplary embodiments clearly show the advantages of the process of the invention and the benefits of using the process of the invention.

The present invention provides a catalytic hydrocracking process that simultaneously hydroprocesses two feedstocks to improve the yield and quality of the liquid product, thereby greatly improving the yield and product properties of a low conversion per pass process.

Claims (10)

(a) a hydrocracking zone operating at a temperature of 204 ° C. to 482 ° C., a pressure of 3.44 mPa to 17.2 mPa, and a liquid hourly space velocity of 0.1 ^{hr −1} to 15 ^{hr −1} and containing a hydrocracking catalyst. 1 passing the hydrocarbon feedstock and hydrogen and recovering the hydrocracking zone emissions from the hydrocracking zone, (b) boiling a first vapor stream comprising hydrogen, hydrogen sulfide and a hydrocarbon compound boiling at a lower temperature than the first hydrocarbon feedstock using a hydrogen-rich hot stripping gas and boiling in the range of the first hydrocarbon feedstock Directly passing the hydrocracking zone discharge through a high temperature, high pressure stripper to produce a first liquid stream comprising a hydrocarbon compound, (c) passing a second hydrocarbon feedstock having a boiling temperature range lower than the first hydrocarbon feedstock into the upper end of the stripper to serve as reflux; (d) passing at least a portion of the first vapor stream recovered in step (b) through a separate vessel containing a post-treatment hydrogenation reaction zone to saturate the aromatic compound, (e) a second liquid stream comprising a hydrocarbon compound that condenses at least a portion of the resulting effluent from the post-treatment hydrogenation reaction zone to boil at a lower temperature than the first hydrocarbon feedstock, and a second liquid stream comprising hydrogen and hydrogen sulfide 2 generating a steam stream, (f) recycling at least a portion of the second vapor stream to the hydrocracking zone A hydrotreating method of simultaneously hydrotreating two feedstocks having different boiling ranges comprising a. The process of claim 1 wherein the second vapor stream comprising hydrogen and hydrogen sulfide is treated to remove at least a portion of hydrogen sulfide. The process of claim 1, wherein the second vapor stream comprises less than 50 wppm hydrogen sulfide. The process of claim 1, wherein the first hydrocarbon feedstock is boiling in the range of 315 ° C. to 565 ° C. and the second hydrocarbon feedstock is boiling in the range of 149 ° C. to 382 ° C. 7. The process of claim 1, wherein the high temperature, high pressure stripper operates at the same temperature and pressure as the hydrocracking zone. The hydrotreating process of claim 1 wherein the high temperature, high pressure stripper operates at a temperature as low as 84 ° C. below the outlet temperature of the hydrocracking zone and at a pressure as low as 1.03 mPa below the outlet pressure of the hydrocracking zone. Way. The process of claim 1, wherein the hydrocracking zone operates at a conversion per pass in the range of 10% to 50%. The process of claim 1, wherein the hydrocracking zone operates at a conversion per pass in the range of 20% to 40%. The process of claim 1, wherein at least a portion of the first liquid stream is recycled to the hydrocracking zone. The process of claim 1, wherein the post-treatment hydrogenation reaction zone is operated at reaction zone conditions comprising a temperature of 204 ° C. to 482 ° C. and a pressure of 3.44 mPa to 17.2 mPa.