A method for jointly producing chemical raw materials by coking and hydrocracking

Abstract

The present invention discloses a method for jointly producing chemical raw materials by coking and hydrocracking. The method comprises: the coking raw materials enter a delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and a gaseous effluent; the gaseous effluent is fractionated to obtain coker dry gas, coker light distillate oil and coker wax oil; in the presence of hydrogen, the coker light distillate oil raw materials are mixed with hydrogen and sequentially enter a first hydrocracking reaction zone and a second hydrocracking reaction zone for reaction, and the obtained second hydrocracking product is separated and fractionated to obtain gas, light naphtha, heavy naphtha and tail oil; the tail oil is mixed with hydrogen and enters a third hydrocracking reaction zone to obtain a third hydrocracking product, which is separated and fractionated to obtain gas, light naphtha and heavy naphtha; the reaction pressure of the first hydrocracking reaction zone is 0.5-5.0 MPa higher than that of the third hydrocracking reaction zone. This method can greatly improve the yield and quality of chemical raw materials.

Description

Technical Field

[0001] The present invention belongs to the field of heavy oil processing, and particularly relates to a method for jointly producing chemical raw materials by delayed coking and hydrocracking, especially a processing method for producing high-quality chemical raw materials from vacuum residue as the raw material. Background Art

[0002] Reducing the production of heavy fuel oil is the development trend of the world's refining industry today. Although the current capacity of catalytic cracking for single refining and blending residue oil has accounted for more than 25% of the total catalytic cracking capacity, not all residue oils can be processed by catalytic cracking. If the carbon residue content of the residue oil exceeds 10% and the metal content exceeds 100 - 150 ppm, the residue oil hydrotreating / catalytic cracking combined unit will also have difficulty bearing the increasingly high catalyst cost and the increasingly long shutdown time. Coupled with the growing demand for light oil products, the widening price difference between light crude oil and heavy high-sulfur crude oil, and the increasing proportion of heavy sulfur-containing / high-sulfur crude oil supply, especially since delayed coking can process cheap heavy high-sulfur high-metal residue oil, and coker gasoline can be used as a raw material for ethylene production after hydrogenation, delayed coking has thus become the most popular technology for residue oil processing and the preferred residue oil processing scheme for many refineries.

[0003] CN201580070326.4 discloses a method for preparing LPG and BTX, comprising: a) subjecting a mixed hydrocarbon stream to a first hydrocracking in the presence of a first hydrocracking catalyst to prepare a first hydrocracking product stream; b) separating the first hydrocracking product stream to provide at least one light hydrocarbon stream containing at least C2 and C3 hydrocarbons, an intermediate hydrocarbon stream composed of C4 and / or C5 hydrocarbons, and a heavy hydrocarbon stream containing at least C6+ hydrocarbons, and c) subjecting the heavy hydrocarbon stream to a second hydrocracking in the presence of a second hydrocracking catalyst to prepare a second hydrocracking product stream containing BTX, wherein the second hydrocracking is more severe than the first hydrocracking, d) wherein, in the presence of a C4 hydrocracking catalyst, at least part of the intermediate hydrocarbon stream is subjected to C4 hydrocracking to prepare a C4 hydrocracking product stream, and the C4 hydrocracking is optimized for converting C4 hydrocarbons into C3 hydrocarbons.

[0004] CN201480037272.7 discloses a method for producing light olefin hydrocarbon compounds from a hydrocarbon raw material, comprising the following steps: (a) feeding the hydrocarbon raw material to a reaction zone for ring opening; (b) separating the reaction product generated from the reaction zone into an overhead stream and a side stream; (c) feeding the side stream from (b) to a gasoline hydrocracker (GHC) unit; (d) separating the reaction product of the GHC in step (c) into an overhead stream containing hydrogen, methane, ethane, and liquefied petroleum gas and a stream containing aromatic hydrocarbon compounds and a small amount of hydrogen and non-aromatic hydrocarbon compounds; (e) feeding the overhead stream from the gasoline hydrocracker (GHC) unit to a steam cracker unit.

[0005] In summary, petroleum hydrocarbons have a complex composition, mainly including alkanes, cycloalkanes, and aromatics. Among them, alkanes, especially small-molecule alkanes, are high-quality ethylene raw materials, while cycloalkanes and aromatics are high-quality reforming feeds. Delayed coking causes heavy raw materials to undergo thermal cracking, following the free radical reaction mechanism. The products have a high content of n-paraffins and cyclic hydrocarbons. In the existing technology, it is impossible to efficiently achieve the conversion effect of "ethylene for ethylene and aromatics for aromatics" for coker distillate oil. Therefore, it is of great significance to develop a processing method suitable for producing high-quality chemical raw materials from heavy oils such as vacuum residue through delayed coking and hydrocracking. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a method for jointly producing chemical raw materials by coking and hydrocracking. This method uses heavy oils such as vacuum residue as raw materials and can significantly improve the quality and yield of chemical raw materials.

[0007] The present invention provides a method for jointly producing chemical raw materials by coking and hydrocracking, and the method includes:

[0008] (1) The coking raw material enters the delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and a gaseous effluent; the gaseous effluent is fractionated to obtain coker dry gas, coker light distillate oil, and coker wax oil;

[0009] (2) In the presence of hydrogen, the coker light distillate oil raw material obtained in step (1) is mixed with hydrogen and enters the first hydrocracking reaction zone for the first hydrocracking, and the mass content of C7 + n-paraffins in the first hydrocracking product is controlled at 0.1% - 5.0%;

[0010] (3) The reaction effluent from step (2) enters the second hydrocracking reaction zone to selectively open and crack polycyclic cyclic hydrocarbons to obtain a second hydrocracking product; the hydrogen-rich gas obtained after the gas-liquid separation of the second hydrocracking product through a separator is used as recycle hydrogen, and the liquid phase enters the fractionation system for fractionation to obtain gas, light naphtha, heavy naphtha, and tail oil;

[0011] (4) The tail oil from step (3) is mixed with hydrogen and enters the third hydrocracking reaction zone to obtain a third hydrocracking product containing monocyclic cyclic hydrocarbons, and the third hydrocracking product enters the separation and fractionation system to obtain gas, light naphtha, and heavy naphtha;

[0012] The reaction pressure in the first hydrocracking reaction zone in step (2) is 0.5 - 5.0 MPa higher than the reaction pressure in the third hydrocracking reaction zone in step (4).

[0013] According to the present invention, the coking feedstock oil in step (1) is generally heavy oil with an initial boiling point greater than 350 °C, and can be selected from one or more of atmospheric residue, vacuum residue, visbreaking residue, heavy deasphalted oil, catalytic cracking slurry, heavy oil, topped crude oil, shale oil, and coal liquefied oil, preferably vacuum residue. The initial boiling point of the vacuum residue is 420 °C to 620 °C, preferably 450 °C to 550 °C; the sulfur mass content is 2% to 10%, preferably 4% to 8%; the nitrogen mass content is 0.2% to 1.0%, preferably 0.3% to 0.5%; the metal content is 100 mg / kg to 500 mg / kg, preferably 200 mg / kg to 300 mg / kg.

[0014] According to the present invention, the temperature in the delayed coking reaction zone in step (1) is 480 to 520 °C, preferably 490 to 505 °C; the operating pressure is 0.1 MPa to 2 MPa, preferably 0.2 MPa to 0.5 MPa, and it can be a constant pressure operation or a variable pressure operation; the recycle ratio is 0.1 to 0.5, preferably 0.2 to 0.4, and the recycle ratio is the mass ratio of coker gas oil to feedstock oil. The initial boiling point of the coker gas oil is 280 °C to 340 °C, preferably 290 °C to 320 °C; the final boiling point is 450 °C to 580 °C, preferably 480 °C to 520 °C.

[0015] According to the present invention, the initial boiling point of the coking light distillate oil in step (1) is 50 °C to 80 °C, preferably 60 °C to 70 °C; the final boiling point is 280 °C to 340 °C, preferably 290 °C to 320 °C.

[0016] According to the present invention, the mass content of tricyclic aromatic hydrocarbons in the coking light distillate oil in step (1) is not higher than 1.0%, preferably 0.2% to 0.6%.

[0017] According to the present invention, the chemical raw materials mainly include ethane, propane, butane, light naphtha, and may also include heavy naphtha. Among them, heavy naphtha is used as a reforming feedstock to produce BTX, and ethane, propane, butane, and light naphtha are used as raw materials for producing light olefins. For example, they are used as steam cracking feedstock to produce ethylene, and propane and butane can also be directly dehydrogenated to produce propylene and butene. Among them, light olefins refer to olefins with four or fewer carbon atoms, especially ethylene, propylene, and butadiene.

[0018] According to the present invention, preferably, the reaction pressure in the first hydrocracking reaction zone in step (2) is 0.5 to 5.0 MPa higher than the reaction pressure in the third hydrocracking reaction zone in step (4).

[0019] According to the present invention, preferably, the reaction pressure in the first hydrocracking reaction zone in step (2) is 0.5 to 3.0 MPa higher than the reaction pressure in the third hydrocracking reaction zone in step (4).

[0020] According to the present invention, in step (2), the mass content of C7 n-alkanes in the first hydrocracking product + is 1.0% to 3.0%.

[0021] According to the present invention, in step (2), the reaction conditions in the first hydrocracking reaction zone are as follows: the reaction pressure is 5 to 10 MPa, preferably 6 to 8 MPa.

[0022] According to the present invention, in step (2), the reaction conditions in the first hydrocracking reaction zone are as follows: the average reaction temperature is 250 to 450 °C, preferably 300 to 400 °C; the liquid hourly space velocity is 0.1 to 15.0 h -1 , preferably 1.0 to 5.0 h -1 ; the hydrogen-oil volume ratio is 100:1 to 2500:1, preferably 400:1 to 2000:1.

[0023] According to the present invention, in step (2), the coker light distillate oil may contain impurities such as sulfur and nitrogen. According to actual needs, a hydrofining catalyst may be provided upstream of the first hydrocracking catalyst to remove impurities such as sulfur and nitrogen. Among them, the nitrogen content in the reaction fluid in contact with the first hydrocracking catalyst is preferably below 50 mg / kg, more preferably below 20 mg / kg.

[0024] According to the present invention, in step (2), the first hydrocracking reaction zone is filled with a first hydrocracking catalyst. The first hydrocracking catalyst may be one or more catalysts.

[0025] According to the present invention, in step (2), a hydrofining catalyst may be provided upstream of the first hydrocracking catalyst, which may use a conventional hydrofining catalyst, mainly for hydrodesulfurization, denitrification and other impurities. The hydrofining catalyst includes a carrier and a hydroactive metal. The carrier is an inorganic refractory oxide, generally selected from one or several of alumina, amorphous silica-alumina, silica or titanium oxide, etc.; the hydroactive metal includes Group VIB and / or Group VIII metal components. In the hydrofining catalyst, Group VIB is preferably selected from tungsten and / or molybdenum, and its content in the catalyst is 5% to 30% by mass of the oxide, preferably 10% to 20%; Group VIII is preferably selected from nickel and / or cobalt, and its content in the catalyst is 1% to 6% by mass of the oxide, preferably 1.5% to 5%. The carrier, by mass of the oxide, accounts for 64% to 94% in the catalyst, preferably 75% to 88.5%.

[0026] According to the present invention, in step (2), the first hydrocracking catalyst comprises an active metal component and a support; the support comprises a molecular sieve having a selectivity for cracking n-paraffins, preferably selected from one or more of ZSM-5 molecular sieve, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35 and ZSM-38 molecular sieves, preferably ZSM-5 molecular sieve. The SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 20 to 60. The support may further comprise a binder. Preferably, the binder is alumina. The active metal component comprises at least one of metals of Group VIB and Group VIII, the metal of Group VIB is preferably molybdenum and / or tungsten, and the metal of Group VIII is preferably cobalt and / or nickel.

[0027] According to the present invention, in step (2), preferably, in the first hydrocracking catalyst, based on the weight of the catalyst, the content of the metal of Group VIB (calculated as the oxide) is 5.0% to 15.0%, the content of the metal of Group VIII (calculated as the oxide) is 2.0% to 5.0%, and the content of the support is 80.0% to 93.0%.

[0028] According to the present invention, in step (2), preferably, in the support of the first hydrocracking catalyst, based on the weight of the support, the content of the binder is 8% to 60%, and the content of the molecular sieve is 40% to 92%.

[0029] According to the present invention, in step (2), the specific surface area of the first hydrocracking catalyst is 200 to 400 m 2 / g, and the pore volume is 0.25 to 0.45 mL / g.

[0030] According to the present invention, the preparation method of the first hydrocracking catalyst in step (2) can be prepared according to the conventional methods in the art. The preparation method includes the preparation of the support and the loading of the active metal component. The process of preparing the support is as follows: the shape-selective cracking molecular sieve and the binder are mechanically mixed, formed, and then dried and calcined to make the catalyst support. The drying and calcining of the support can adopt conventional conditions. The conditions for drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for calcining are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0031] According to the present invention, in step (2), in the preparation method of the first hydrocracking catalyst, the method for loading the active metal component is a conventional method, such as kneading method, impregnation method, etc., and the impregnation method is preferably used. The impregnation method can be saturated impregnation method, excess impregnation method or complex impregnation method, that is, the catalyst support is impregnated with a solution containing the required active component, and then dried and calcined to obtain the first hydrocracking catalyst. The conditions for drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for calcination are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0032] According to the present invention, in step (3), the separation and fractionation of the second hydrocracking product and the third hydrocracking product in step (4) preferably share a set of separation and fractionation systems.

[0033] According to the present invention, in step (3), the reaction conditions in the second hydrocracking reaction zone are as follows: the reaction pressure is 5 to 10 MPa, preferably 6 to 8 MPa.

[0034] According to the present invention, in step (3), the reaction conditions for the second hydrocracking reaction are as follows: the average reaction temperature is 250 to 450°C, preferably 300 to 400°C; the liquid hourly space velocity is 0.1 to 15.0 h -1 , preferably 1.0 to 5.0 h -1 ; the hydrogen-oil volume ratio is 100:1 to 2500:1, preferably 400:1 to 2000:1.

[0035] According to the present invention, preferably, the first hydrocracking reaction zone and the second hydrocracking reaction zone adopt the same reaction pressure.

[0036] According to the present invention, in step (3), the second hydrocracking reaction zone is filled with a second hydrocracking catalyst. The second hydrocracking catalyst can be one or more catalysts.

[0037] According to the present invention, in step (4), the third hydrocracking reaction zone is filled with a third hydrocracking catalyst. The third hydrocracking catalyst can be one or more catalysts.

[0038] According to the present invention, the second hydrocracking catalyst in step (3) has the function of ring-opening cracking of polycyclic cyclic hydrocarbons.

[0039] According to the present invention, the third hydrocracking catalyst in step (4) has the function of selectively cracking isoparaffins or the side chains of cyclic hydrocarbons and retaining monocyclic cyclic hydrocarbons.

[0040] According to the present invention, the second hydrocracking catalyst described in step (3) and / or the third hydrocracking catalyst described in step (4) comprise a cracking component, a hydrogenation component and a binder. The second hydrocracking catalyst and / or the third hydrocracking catalyst can be commercially available products or prepared according to the prior art. The hydrogenation component is at least one of a metal, a metal oxide and a metal sulfide of an active metal component; the active metal component comprises a Group VIB and / or Group VIII metal; the active metal component is more preferably at least one of iron, chromium, molybdenum, tungsten, cobalt and nickel. The binder is alumina and / or silica; the cracking component comprises an acidic molecular sieve, preferably at least one of Beta zeolite and Y zeolite.

[0041] According to the present invention, it is further preferred that the cracking component of the second hydrocracking catalyst in step (3) is Y zeolite.

[0042] According to the present invention, it is further preferred that the cracking component of the third hydrocracking catalyst in step (4) is Beta zeolite.

[0043] In the second hydrocracking catalyst described in step (3) and / or the third hydrocracking catalyst described in step (4) according to the present invention, based on the mass of the catalyst, the content of the hydrogenation component in terms of oxide is 5 wt% to 40 wt%, preferably 10 wt% to 30 wt%; the content of the cracking component is 10 wt% to 80 wt%, preferably 20 wt% to 60 wt%; the content of the binder is 5 wt% to 85 wt%, preferably 10 wt% to 50 wt%.

[0044] According to the present invention, the preparation method of the second hydrocracking catalyst described in step (3) and / or the third hydrocracking catalyst described in step (4) can be prepared according to the conventional methods in the art. The preparation method includes the preparation of a carrier and the loading of a hydrogenation component, and the process of preparing the carrier is as follows: the cracking component and the binder are mechanically mixed, formed, and then dried and calcined to make a catalyst carrier. The drying and calcination of the carrier can adopt conventional conditions. The conditions for drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for calcination are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0045] According to the present invention, in the preparation method of the second hydrocracking catalyst described in step (3) and / or the third hydrocracking catalyst described in step (4), the method for loading the hydrogenation component is a conventional method, such as kneading method, impregnation method, etc., and the impregnation method is preferred. The impregnation method can be saturated impregnation method, excess impregnation method or complex impregnation method, that is, the catalyst carrier is impregnated with a solution containing the required hydrogenation component, and then dried and calcined to obtain a hydrocracking catalyst. The conditions for the drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for the calcination are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0046] According to the present invention, in the third hydrocracking product of step (4), the mass ratio of the C6-C8 monocyclic cyclic hydrocarbons to the total cyclic hydrocarbons in the coker light distillate oil raw material is 0.35 to 0.55, preferably 0.42 to 0.50.

[0047] According to the present invention, the reaction conditions in the third hydrocracking reaction zone of step (4) are as follows: the reaction pressure is 3 to 7 MPa, preferably 3 to 6 MPa.

[0048] According to the present invention, the reaction conditions in the third hydrocracking reaction zone of step (4) are as follows: the average reaction temperature is 250 to 450°C, preferably 300 to 400°C; the liquid hourly space velocity is 0.1 to 15.0 h -1 , preferably 1.0 to 5.0 h -1 ; the hydrogen-oil volume ratio is 100:1 to 2500:1, preferably 400:1 to 2000:1.

[0049] Petroleum hydrocarbons have a complex composition, mainly including alkanes, cycloalkanes and aromatics, while high-quality ethylene raw materials are small-molecule n-alkanes, and reforming raw materials are monocyclic cycloalkanes and aromatics. The inventors have found through research that the coker light distillate oil raw material can pass through the shape-selective cracking of straight-chain alkanes, the ring-opening cracking of polycyclic cyclic hydrocarbons, and the selective hydrocracking of long side chains on isoparaffins or cyclic hydrocarbons in sequence to retain monocyclic cyclic hydrocarbons as much as possible, and can selectively generate small-molecule n-alkanes, so as to efficiently enrich small-molecule n-alkanes in low-carbon olefin raw materials, and at the same time retain monocyclic cyclic hydrocarbons in heavy naphtha as much as possible to achieve efficient enrichment of high-quality reforming raw materials, so as to achieve the purpose of greatly improving the yields of chemical raw materials (i.e., low-carbon olefin raw materials and reforming raw materials) and the qualities of low-carbon olefin raw materials and reforming raw materials, thereby completing the present invention.

[0050] Compared with the prior art, the present invention has the following beneficial technical effects:

[0051] (1) In the prior art, when hydrocracking coker diesel as a raw material to produce chemical raw materials, the final boiling point of the coker diesel fractionated from the coker distillate is generally 350-380 °C. This also results in a relatively high content of tricyclic aromatics in the coker diesel fraction, and a relatively high reaction pressure is required to achieve the hydrocracking of tricyclic aromatics. However, a relatively high reaction pressure will also cause some monocyclic aromatics to open-ring crack during the hydrocracking process, resulting in the loss of aromatics. In the method for jointly producing chemical raw materials by coking and hydrocracking in the present invention, after the coker distillate oil enters the fractionating tower, by controlling the content of tricyclic aromatics in the top oil of the fractionating tower to be no higher than 1%, and selecting an appropriate reaction pressure, the mixed processing of monocyclic aromatics and bicyclic aromatics is realized, the loss of aromatics in the hydrogenation process of the raw materials is reduced, and the aromatic content in the hydrogenation product is increased. Specifically, the obtained light coker distillate oil is mixed with hydrogen and enters the first hydrocracking reaction zone, mainly selectively cracking the n-paraffins in the raw materials and the long straight chains of isoparaffins and naphthenes containing long straight chains to generate small molecule n-paraffins, so that the content of C7 + n-paraffins in the effluent of the first hydrocracking reaction is 0.1%-5.0%. The effluent of the first hydrocracking reaction enters the second hydrocracking reaction zone, mainly to open-ring crack the polycyclic cyclic hydrocarbons and retain the monocyclic cyclic hydrocarbons and further break the side chains in each hydrocarbon to generate small molecule hydrocarbons. In this way, a large amount of the linear alkanes in the raw materials can be converted into gas and light naphtha components, that is, enriched in ethylene raw materials, while the monocyclic cyclic hydrocarbons are retained in the heavy naphtha fraction, that is, enriched in reforming raw materials. Through simple fractionation, the efficient separation of linear alkanes and cyclic hydrocarbons can be realized, increasing the production of high-quality ethylene cracking feedstock while improving the quality of heavy naphtha as a catalytic reforming feedstock.

[0052] (2) The content of monocyclic cyclic hydrocarbons in the heavy naphtha obtained by the method of the present invention is high. As the feedstock for the catalytic reforming unit, the alkane cyclization and dehydrogenation unit in the catalytic reforming unit can be cancelled, which can greatly reduce the investment and energy consumption of the catalytic reforming unit; at the same time, since the hydrocracking reaction follows the carbocation reaction mechanism, the side chains of cyclic hydrocarbons above C9 can be selectively cracked, so that the C6-C8 cyclic hydrocarbons in the product have a relatively high enrichment degree. After catalytic reforming and aromatics extraction, the BTX yield can be greatly increased.

[0053] (3) The present invention selectively converts the linear alkanes in the light coker distillate oil into small molecule alkanes. This process will consume a certain amount of hydrogen, but the light hydrocarbons also have a high hydrogen yield as the raw material for the ethylene unit, and the lower the carbon number, the higher the hydrogen yield. Therefore, most of the hydrogen consumed in the hydrogenation process can be recovered after passing through the ethylene unit. At the same time, the light hydrocarbons as ethylene raw materials can greatly increase the yields of ethylene, propylene and butadiene, and extend the cleaning cycle of the ethylene unit, significantly improving the economic benefits of the unit. Description of the Drawings

[0054] Figure 1It is a schematic process flow diagram of the process method of the present invention;

[0055] Main reference numerals description:

[0056] 1 - Vacuum residue, 2 - Delayed coking reaction zone, 3 - Petroleum coke, 4 - Delayed coking gas-phase effluent, 5 - Fractionating tower, 6 - Coking gas fraction, 7 - Coking light distillate oil, 8 - Coking wax oil, 9 - Hydrogen, 10 - First hydrocracking reaction zone, 11 - First hydrocracking reaction effluent, 12 - Second hydrocracking reaction zone, 13 - Second hydrocracking reaction effluent, 14 - Separator, 15 - Gas-phase stream rich in hydrogen gas, 16 - Liquid-phase stream, 17 - Fractionating tower, 18 - Gas fraction, 19 - Light naphtha, 20 - Heavy naphtha, 21 - Tail oil, 22 - Third hydrocracking reaction zone, 23 - Third hydrocracking reaction zone effluent. Detailed implementation manners

[0057] The functions and effects of the present invention will be further described below through examples, but the following examples do not limit the method of the present invention.

[0058] In the present invention, unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, unless it does not conform to the common understanding of those skilled in the art when based on weight.

[0059] In the present invention, the overall volume space velocity in the examples and comparative examples is the ratio of the volume of fresh feed to the total volume of the catalyst.

[0060] In the present invention, as Figure 1 shown, it includes: Vacuum residue 1 enters the delayed coking reaction zone 2 to obtain petroleum coke 3 and delayed coking gas-phase effluent 4. The delayed coking gas-phase effluent 4 enters the fractionating tower 5 for separation to obtain coking gas fraction 6, coking light distillate oil 7 and coking wax oil 8. The coking light distillate oil 8 is mixed with hydrogen 9 and enters the first hydrocracking reaction zone 10 for hydrocracking reaction. The first hydrocracking reaction effluent 11 enters the second hydrocracking reaction zone 12. The second hydrocracking reaction effluent 13 enters the separator 14. The separated gas-phase stream rich in hydrogen gas 15 is recycled. The liquid-phase stream 16 enters the fractionating tower 17 for fractionation to obtain gas fraction 18, light naphtha 19, heavy naphtha 20 and tail oil 21. The tail oil 21 is mixed with hydrogen 9 and enters the third hydrocracking reaction zone 22. The third hydrocracking reaction effluent 23 enters the separator 14 for separation and fractionation.

[0061] In the present invention, the first hydrocracking catalyst in each example is represented by Cat-A plus a number, such as Cat-A1, Cat-A2, Cat-A3, Cat-A4. The first hydrocracking catalyst is prepared by a conventional active metal saturation impregnation method, and the physicochemical properties of the obtained catalyst are shown in Table 1.

[0062] In the present invention, the second hydrocracking catalyst in each example is denoted as Cat-B, and the physical and chemical properties of the catalyst are shown in Table 2.

[0063] In the present invention, the third hydrocracking catalyst in each example is denoted as Cat-C, and the physical and chemical properties of the catalyst are shown in Table 2.

[0064] In the present invention, the second hydrocracking catalyst and the third hydrocracking catalyst in each example are prepared by a conventional active metal saturation impregnation method.

[0065] Among them, the properties of the Beta zeolite used in the catalyst Cat-C are as follows: the SiO2 / Al2O3 molar ratio is 30, the specific surface area is 350 m 2 / g, and the pore volume is 0.32 cm 3 / g. The properties of the Y zeolite used in the catalyst Cat-B are as follows: the SiO2 / Al2O3 molar ratio is 15, the specific surface area is 400 m 2 / g, and the pore volume is 0.30 cm 3 / g. The physical and chemical properties of the obtained catalyst are shown in Table 2.

[0066] In the present invention, the feedstock oil in each example uses a vacuum residue feedstock, and its main properties are shown in Table 3.

[0067] In the present invention, the nitrogen content in the reaction stream contacting the first hydrocracking catalyst in step (2) in each example is below 20 mg / kg.

[0068] In the present invention, the ethylene feedstock in each example refers to ethane, propane, butane, and light naphtha obtained in step (3), and ethane, propane, butane, and light naphtha can be directly used as feedstocks for steam cracking to produce ethylene.

[0069] In the present invention, the distillation range of light naphtha is the liquid component with a boiling point below 60 °C, and the distillation range of heavy naphtha is 60 - 175 °C.

[0070] In the present invention, the yield of the ethylene feedstock refers to the mass ratio of ethane, propane, butane, and light naphtha in the hydrocracking product to the fresh hydrocracking feedstock (coker light distillate oil), and the yield of heavy naphtha refers to the mass ratio of heavy naphtha in the hydrocracking product to the fresh hydrocracking feedstock (coker light distillate oil).

[0071] Examples 1 - 4

[0072] The method for jointly producing chemical raw materials by coking and hydrocracking adopts the following Figure 1 process, including:

[0073] (1) The vacuum residue enters the delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and gaseous effluent; the gaseous effluent enters the fractionating tower to obtain coker dry gas, coker light distillate oil and coker wax oil;

[0074] (2) The coker light distillate oil is mixed with hydrogen and enters the first hydrocracking reaction zone; the first hydrocracking reaction zone is filled with the first hydrocracking catalyst; in step (2), the content of C7 + n-alkanes in the effluent of the first hydrocracking reaction should be controlled.

[0075] (3) The effluent of the first hydrocracking reaction obtained in step (2) enters the second hydrocracking reaction zone, and the second hydrocracking reaction zone is filled with the second hydrocracking catalyst; the reaction is carried out under the action of the catalyst to obtain the second hydrocracking product. The hydrogen-rich gas obtained after the separation and fractionation of the second hydrocracking product is used as recycle hydrogen, and the liquid phase enters the fractionating tower for fractionation to obtain gas, light naphtha, heavy naphtha and tail oil;

[0076] (4) The tail oil of step (3) enters the third hydrocracking reaction zone, and the third hydrocracking reaction zone is filled with the third hydrocracking catalyst; the effluent of the third hydrocracking reaction shares a set of separation and fractionation systems with the effluent of the second hydrocracking reaction.

[0077] The process conditions and hydrotreating effects of each example are shown in Table 5.

[0078] Comparative Example 1

[0079] The difference from Example 1 is that: the coker light distillate oil directly enters the second hydrocracking reaction zone without the first hydrocracking.

[0080] The process conditions and hydrotreating effects in this example are shown in Table 5.

[0081] Comparative Example 2

[0082] The difference from Example 1 is that: in step (1), the content of C7 + n-alkanes in the effluent of the first hydrocracking reaction is 6%.

[0083] The process conditions and hydrotreating effects in this example are shown in Table 5.

[0084] Comparative Example 3

[0085] The difference from Example 1 is that: the catalysts in the second and third hydrocracking reaction zones are exchanged. Specifically: the second hydrocracking reaction zone is filled with catalyst Cat-C, and the third hydrocracking reaction zone is filled with catalyst Cat-B.

[0086] The process conditions and hydrotreating effects in this example are shown in Table 5.

[0087] Comparative Example 4

[0088] The difference from Example 1 is that the reaction pressure in the first hydrocracking reaction zone is the same as that in the third hydrocracking reaction zone.

[0089] The process conditions and hydrogenation effects in this example are shown in Table 5.

[0090] Comparative Example 5

[0091] The difference from Example 1 is that the mass content of tricyclic aromatic hydrocarbons in the coker light distillate oil is 3.1%.

[0092] The process conditions and hydrogenation effects in this example are shown in Table 5.

[0093] Table 1 Physicochemical properties of the first hydrocracking catalyst

[0094] Catalyst Cat-A1 Cat-A2 Cat-A3 Cat-A4 <![CDATA[Pore volume, cm 3 / g]]> 0.35 0.45 0.25 0.30 <![CDATA[Specific surface area, m 2 / g]]> 300 200 400 350 Content, wt%, based on the weight of the carrier ZSM-5 58 42 85 75 Aluminum oxide 42 58 15 25 Active metal content in the catalyst, wt% <![CDATA[MoO3]]> 10.0 15.0 5.0 12.5 NiO 3.5 2.0 5.0 4.0 <![CDATA[SiO2 / Al2O3 molar ratio of ZSM-5]]> 40 60 20 50

[0095] Table 2 Physicochemical properties of the second hydrocracking catalyst and the third hydrocracking catalyst

[0096] Catalyst properties Cat-C Cat-B <![CDATA[Pore volume, cm 3 / g]]> 0.35 0.35 <![CDATA[Specific surface area, m 2 / g]]> 300 300 Catalyst composition and content Beta, wt% 50 - Y, wt% - 30 <![CDATA[MoO3, wt%]]> 10 20 NiO, wt% 5 5 Aluminum oxide, wt% 35 45

[0097] Table 3 Main properties of the raw materials

[0098] Name of feedstock oil Vacuum residue <![CDATA[Density (20 °C) / kg·m -3 > 1.032 Distillation range / °C IBP / 10% 464 / 558 30％ / 50％ 606 / 646 70％ / 90％ 749 / 973 95% / EBP 1025 / 1055 Sulfur content, wt% 5.61 Nitrogen content, wt% 0.38 Ni+V, mg / kg 200

[0099] Table 4 Delayed coking process conditions and main properties of coker light distillate oil

[0100]

[0101] Continued Table 4

[0102]

[0103] Table 5 Hydrogenation effects

[0104]

[0105]

[0106] Continued Table 5

[0107]

[0108]

[0109] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for jointly producing chemical raw materials by coking and hydrocracking, the method comprising: (1) Feeding coking feedstock into a delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and a gaseous effluent; The gaseous effluent is fractionated to obtain coker dry gas, coker light distillate oil and coker wax oil; (2) In the presence of hydrogen, the coking light distillate oil raw material obtained in step (1) is mixed with hydrogen and enters the first hydrocracking reaction zone for the first hydrocracking, and the mass content of C7 + normal paraffin in the first hydrocracking product is controlled to be 0.1% - 5.0%; (3) The reaction effluent from step (2) enters a second hydrocracking reaction zone to selectively open-ring crack polycyclic hydrocarbons above two rings to obtain a second hydrocracking product; The hydrogen-rich gas obtained after the second hydrocracking product is subjected to gas-liquid separation in a separator is used as recycle hydrogen, and the liquid phase enters a fractionation system for fractionation to obtain gas, light naphtha, heavy naphtha and tail oil; (4) The tail oil from step (3) is mixed with hydrogen and enters a third hydrocracking reaction zone to obtain a third hydrocracking product containing monocyclic hydrocarbons, and the third hydrocracking product enters a separation and fractionation system to obtain gas, light naphtha and heavy naphtha; The reaction pressure in the first hydrocracking reaction zone in step (2) is 0.5 to 5.0 MPa higher than the reaction pressure in the third hydrocracking reaction zone in step (4); In step (1), the mass content of tricyclic aromatic hydrocarbons in the coker light distillate oil is not higher than 1.0%; In step (2), the first hydrocracking reaction zone is filled with a first hydrocracking catalyst; the first hydrocracking catalyst includes an active metal component and a carrier; the carrier includes a molecular sieve having selective cracking of normal paraffins, and the molecular sieve is selected from one or more of ZSM-5 molecular sieve, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35 and ZSM-38 molecular sieves; the active metal component includes at least one of Group VIB metals and Group VIII metals; In step (2), for the first hydrocracking catalyst, based on the weight of the catalyst, the content of Group VIB metal in terms of oxide is 5.0% to 15.0%, the content of Group VIII metal in terms of oxide is 2.0% to 5.0%, and the content of the carrier is 80.0% to 93.0%; in the carrier of the first hydrocracking catalyst, based on the weight of the carrier, the content of the binder is 8% to 60%, and the content of the molecular sieve is 40% to 92%; In step (3), the second hydrocracking reaction zone is filled with a second hydrocracking catalyst; In step (4), the third hydrocracking reaction zone is filled with a third hydrocracking catalyst; The second hydrocracking catalyst in step (3) and the third hydrocracking catalyst in step (4) include a cracking component, a hydrogenation component and a binder; The cracking component of the second hydrocracking catalyst in step (3) is Y molecular sieve; The cracking component of the third hydrocracking catalyst in step (4) is Beta molecular sieve; In the second hydrocracking catalyst in step (3) and the third hydrocracking catalyst in step (4), based on the mass of the catalyst, the content of the hydrogenation component in terms of oxide is 5 wt% to 40 wt%; the content of the cracking component is 10 wt% to 80 wt%; the content of the binder is 5 wt% to 85 wt%; The chemical raw materials include ethane, propane, butane, light naphtha and heavy naphtha. Among them, heavy naphtha is used as a reforming raw material to produce BTX, and ethane, propane, butane and light naphtha are used as raw materials for producing lower olefins.

2. The method according to claim 1, wherein In step (2), the reaction pressure in the first hydrocracking reaction zone is 0.5 - 3.0 MPa higher than the reaction pressure in the third hydrocracking reaction zone in step (4).

3. The method according to claim 1, characterized in that, In step (2), the reaction pressure in the first hydrocracking reaction zone is 5 - 10 MPa.

4. The method according to claim 1, characterized in that In step (2), the reaction pressure in the first hydrocracking reaction zone is 6 - 8 MPa.

5. The method according to claim 1, wherein In step (1), the coking feedstock oil is heavy oil with an initial boiling point greater than 350 °C, and is selected from one or more of atmospheric residue, vacuum residue, visbreaking residue, heavy deasphalted oil, catalytic cracking slurry, heavy oil, topped crude oil, shale oil and coal liquefied oil; And / or, the coking light distillate oil has an initial boiling point of 50 °C - 80 °C; and a final boiling point of 280 °C - 340 °C; And / or, the mass content of tricyclic aromatic hydrocarbons in the coking light distillate oil is 0.2% - 0.6%.

6. The method according to claim 1, wherein The coking light distillate oil has an initial boiling point of 60 °C - 70 °C; and a final boiling point of 290 °C - 320 °C.

7. The method according to claim 1, characterized in that In step (1), the coking feedstock oil is vacuum residue; the vacuum residue has an initial boiling point of 420 °C - 620 °C; a sulfur mass content of 2% - 10%; a nitrogen mass content of 0.2% - 1.0%; and a metal content of 100 mg / kg - 500 mg / kg.

8. The method according to claim 7, wherein The vacuum residue has an initial boiling point of 450 °C - 550 °C; a sulfur mass content of 4% - 8%; a nitrogen mass content of 0.3% - 0.5%; and a metal content of 200 mg / kg - 300 mg / kg.

9. The method according to claim 1, characterized in that, In step (1), the temperature in the delayed coking reaction zone is 480 - 520 °C; the operating pressure is 0.1 MPa - 2 MPa; the recycle ratio is 0.1 - 0.5, and the recycle ratio is the mass ratio of coker gas oil to coking feedstock oil.

10. The method according to claim 1, wherein In step (1), the temperature in the delayed coking reaction zone is 490 - 505 °C; the operating pressure is 0.2 MPa - 0.5 MPa; the recycle ratio is 0.2 - 0.4, and the recycle ratio is the mass ratio of coker gas oil to coking feedstock oil.

11. The method according to claim 1, wherein The reaction conditions for the first hydrocracking reaction in step (2) are as follows: the average reaction temperature is 250 to 450 °C; and / or, the liquid hourly space velocity is 0.1 to 15.0 h -1 ; and / or, the hydrogen-oil volume ratio is 100:1 to 2500:

1.

12. The method according to claim 1, wherein The reaction conditions of the first hydrocracking reaction in step (2) are as follows: the average reaction temperature is 300~400°C; and / or, the liquid hourly space velocity is 1.0~5.0 h -1 ; and / or, the hydrogen-oil volume ratio is 400:1~2000:

1.

13. The method according to claim 1, characterized in that In step (3), the reaction pressure in the second hydrocracking reaction zone is 5 - 10 MPa.

14. The method according to claim 1, wherein In step (3), the reaction pressure in the second hydrocracking reaction zone is 6 - 8 MPa.

15. The method according to claim 1, wherein In step (3), the reaction conditions in the second hydrocracking reaction zone are as follows: the average reaction temperature is 250~450°C; the liquid hourly space velocity is 0.1~15.0 h -1 ; the hydrogen-to-oil volume ratio is 100:1~2500:

1.

16. The method according to claim 1, characterized in that, In step (3), the reaction conditions in the second hydrocracking reaction zone are as follows: the average reaction temperature is 300~400°C; the liquid hourly space velocity is 1.0~5.0 h -1 ; the hydrogen-oil volume ratio is 400:1~2000:

1.

17. The method according to claim 1, characterized in that In step (3), the reaction pressure in the third hydrocracking reaction zone is 3 - 7 MPa.

18. The method according to claim 1, wherein In step (3), the reaction pressure in the third hydrocracking reaction zone is 3 - 6 MPa.

19. The method according to claim 1, characterized in that, In step (3), the reaction conditions in the third hydrocracking reaction zone are as follows: the average reaction temperature is 250 to 450 °C; the liquid hourly space velocity is 0.1 to 15.0 h -1 ; the hydrogen-oil volume ratio is 100:1 to 2500:

1.

20. The method according to claim 1, wherein In step (3), the reaction conditions in the third hydrocracking reaction zone are as follows: the average reaction temperature is 300~400°C; the liquid hourly space velocity is 1.0~5.0 h -1 ; the hydrogen-oil volume ratio is 400:1~2000:

1.

21. The method according to claim 1, wherein In the first hydrocracking catalyst, the molecular sieve is ZSM-5 molecular sieve; the Group VIB metals are molybdenum and / or tungsten, and the Group VIII metals are cobalt and / or nickel.

22. The method according to claim 1, wherein In the second hydrocracking catalyst in step (3) and the third hydrocracking catalyst in step (4), the hydrogenation component is at least one of a metal, a metal oxide, and a metal sulfide of an active metal component; the active metal component includes Group VIB and / or Group VIII metals.

23. The method according to claim 22, wherein In the second hydrocracking catalyst described in step (3) and the third hydrocracking catalyst described in step (4), the active metal component is at least one of iron, chromium, molybdenum, tungsten, cobalt, and nickel.

24. The method according to claim 1, wherein In the third hydrocracking product of step (4), the mass ratio of the C6-C8 single-ring cyclic hydrocarbons to the total cyclic hydrocarbon mass in the coker light distillate oil feedstock is 0.35-0.

55.

25. The method according to claim 1, wherein In the third hydrocracking product of step (4), the mass ratio of the C6-C8 single-ring cyclic hydrocarbons to the total cyclic hydrocarbon mass in the coker light distillate oil feedstock is 0.42-0.50.

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