A method for combined production of chemical raw materials by coking and hydrocracking

Abstract

The present invention discloses a method for combined production of chemical raw materials by coking and hydrocracking. The method includes: coking feedstock enters 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 light distillate oil, wherein the mass content of bicyclic aromatic hydrocarbons is 0.1% to 1.0%; in the presence of hydrogen, the coker light distillate oil enters a first hydrocracking reaction zone to selectively crack the n-paraffins in the hydrocarbon oil feedstock to obtain a first hydrocracking product; wherein, the mass content of C7 + n-paraffins in the first hydrocracking product is controlled at 0.1% to 5.0%; the first hydrocracking product enters a second hydrocracking reaction zone to obtain a second hydrocracking product containing monocyclic cyclic hydrocarbons; the second hydrocracking product is separated and fractionated to obtain a gas fraction, light naphtha, and heavy naphtha. 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 combined production of chemical raw materials by delayed coking and hydrocracking, especially a processing method for producing high-quality chemical raw materials from vacuum residue. 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 of residue oil has accounted for more than 25% of the total capacity of catalytic cracking, 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 and high-metal residue oil, and coker gasoline can be used as a raw material for ethylene production by hydrogenation and cracking 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 a 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 hydrocracking unit (GHC); (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 hydrocracking unit (GHC) to a steam cracking unit.

[0005] In summary, in the prior art, it is impossible to efficiently achieve the conversion effect of "preferably olefinic or preferably aromatic" for coking distillate oil. Therefore, it is of great significance to develop a processing method suitable for producing high-quality chemical raw materials from heavy oil and residue oil through delayed coking and hydrocracking. SUMMARY OF THE INVENTION

[0006] Aiming at the problems existing in the prior art, the present invention provides a method for combining coking and hydrocracking to produce chemical raw materials. This method uses heavy oil such as vacuum residue as raw material, which can significantly improve the quality and yield of chemical raw materials.

[0007] The first aspect of the present invention provides a processing method combining coking and hydrocracking, and the method includes:

[0008] (1) The coking feedstock enters the delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and gaseous effluent; the gaseous effluent is fractionated to obtain coking light distillate oil; wherein, the mass content of bicyclic aromatic hydrocarbons in the coking light distillate oil is 0.1% - 1.0%;

[0009] (2) In the presence of hydrogen, the coking light distillate oil obtained in step (1) enters the first hydrocracking reaction zone to selectively crack the n-alkanes in the hydrocarbon oil feedstock to obtain the first hydrocracking product; wherein, in the first hydrocracking product, the mass content of C7 + n-alkanes is controlled at 0.1% - 5.0%;

[0010] (3) In the presence of hydrogen, the first hydrocracking product enters the second hydrocracking reaction zone to obtain a second hydrocracking product containing monocyclic cyclic hydrocarbons;

[0011] (4) The second hydrocracking product is separated and fractionated to obtain gas fraction, light naphtha, and heavy naphtha.

[0012] According to the present invention, preferably, in the first hydrocracking product of step (2), the mass content of C7 + n-alkanes is controlled at 1.0% - 4.0%.

[0013] According to the present invention, in the second hydrocracking product of step (3), the mass ratio of C6 - C8 monocyclic cyclic hydrocarbons to the total cyclic hydrocarbons in the coking light distillate oil feedstock is 0.40 - 0.80, preferably 0.49 - 0.62.

[0014] According to the present invention, the coking feedstock oil in step (1) is 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 550 °C, preferably 450 °C to 500 °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.

[0015] According to the present invention, in step (1), the coking feedstock oil enters the delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and gaseous effluent; the gaseous effluent is fractionated to obtain coker dry gas, coker light distillate oil, coker diesel oil, and coker wax oil, and the coker wax oil is used as the recycle oil in the coking reaction zone. Among them, the initial boiling point of the coker wax oil is 300 to 400 °C, preferably 320 to 360 °C; the final boiling point is 450 to 600 °C, preferably 500 to 550 °C; the initial boiling point of the coker diesel oil is 180 to 240 °C, preferably 200 to 220 °C; the final boiling point is 300 to 400 °C, preferably 330 to 380 °C.

[0016] According to the present invention, in step (1), the temperature of the delayed coking reaction zone 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 the coker wax oil fraction to the feedstock oil.

[0017] According to the present invention, in step (1), the initial boiling point of the coker light distillate oil is 50 °C to 80 °C, preferably 60 °C to 70 °C, and the final boiling point is 190 °C to 240 °C, preferably 200 °C to 220 °C.

[0018] According to the present invention, preferably, the mass content of bicyclic aromatic hydrocarbons in the coker light distillate oil in step (1) is 0.2% to 0.6%.

[0019] According to the present invention, in step (2), the first hydrocracking reaction zone is filled with a first hydrocracking catalyst, and in step (3), the second hydrocracking reaction zone is filled with a second hydrocracking catalyst. Among them, the first hydrocracking catalyst can be one or more catalysts, and the second hydrocracking catalyst can be one or more catalysts.

[0020] According to the present invention, the chemical raw materials mainly include ethane, propane, butane, and light naphtha, and may further include 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. For example, they are used as steam cracking raw materials to produce ethylene. Propane and butane can also be directly dehydrogenated to produce propylene and butene. Among them, lower olefins refer to olefins with four or fewer carbon atoms, especially ethylene, propylene, and butadiene.

[0021] According to the present invention, in step (2), the first hydrocracking catalyst includes an active metal component and a support; the support includes a molecular sieve having selective cracking of normal 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, and more preferably ZSM-5 molecular sieve. The SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 20 to 60. The support may further include a binder. Preferably, the binder is alumina. The active metal component includes at least one of metals from Group VIB and Group VIII. The metal from Group VIB is preferably molybdenum and / or tungsten, and the metal from Group VIII is preferably cobalt and / or nickel.

[0022] According to the present invention, in step (2), preferably, for the first hydrocracking catalyst, based on the weight of the catalyst, the content of the metal from Group VIB (calculated as the oxide) is 5.0% to 15.0%, the content of the metal from Group VIII (calculated as the oxide) is 2.0% to 5.0%, and the content of the support is 80.0% to 93.0%.

[0023] 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%.

[0024] 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.

[0025] 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 calcination of the support can adopt conventional conditions. The drying conditions are: drying at 100°C to 150°C for 1 to 12 hours. The calcination conditions are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0026] 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 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 active component, and then dried and calcined to obtain the first 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.

[0027] According to the present invention, in step (3), the second hydrocracking catalyst has the function of selectively cracking the side chains of isoparaffins or cyclic hydrocarbons and retaining the monocyclic cyclic hydrocarbons. The second hydrocracking catalyst includes a cracking component, a hydrogenation component and a binder. The second hydrocracking catalyst can be a commercially available product 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 the active metal component; the active metal component includes Group VIB and / or Group VIII metals; the active metal component is more preferably at least one of iron, chromium, molybdenum, tungsten, cobalt, and nickel. In the second hydrocracking catalyst, the binder is alumina and / or silica; the cracking component includes an acidic molecular sieve, preferably at least one of Beta molecular sieve and Y molecular sieve, and more preferably Beta molecular sieve.

[0028] According to the present invention, for the second hydrocracking catalyst in step (3), based on the weight of the second hydrocracking catalyst, the content of the hydrogenation component calculated as the oxide is 5 wt% to 40 wt%, preferably 10 wt% to 20 wt%; the content of the cracking component is 20 wt% to 80 wt%, preferably 30 wt% to 70 wt%; the content of the binder is 5 wt% to 75 wt%, preferably 10 wt% to 50 wt%.

[0029] According to the present invention, the preparation method of the second hydrocracking catalyst in step (3) can be prepared according to the conventional methods in the art. The preparation method includes the preparation of the carrier and the loading of the 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 the catalyst carrier. The drying and calcination of the carrier can adopt conventional conditions. 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.

[0030] According to the present invention, in step (3), in the preparation method of the second hydrocracking catalyst, 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, impregnating the catalyst carrier with a solution containing the required hydrogenation component, and then drying and calcining to obtain the second 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.

[0031] According to the present invention, in step (2), the reaction conditions of the first hydrocracking reaction are as follows: the reaction pressure is 1.0 to 5.0 MPa, preferably 2.0 to 4.0 MPa.

[0032] According to the present invention, in step (1), the reaction conditions of the first 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.

[0033] According to the present invention, in step (2), the reaction conditions of the second hydrocracking reaction are as follows: the reaction pressure is 1.0 to 5.0 MPa, preferably 2.0 to 4.0 MPa.

[0034] According to the present invention, in step (3), the reaction conditions of 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 pressure.

[0036] According to the present invention, preferably, in step (3), the second hydrocracking product is subjected to supplementary hydrofining. The supplementary hydrofining can be to load a hydrofining catalyst at the bottom of the second hydrocracking reaction zone, or it can enter a separate hydrofining reaction zone.

[0037] According to the present invention, preferably, in step (3), the second hydrocracking product can also first enter the fractionation system, and the separated heavy naphtha component is subjected to supplementary hydrofining.

[0038] Petroleum hydrocarbons have a complex composition, mainly including alkanes, cycloalkanes and aromatics. High-quality ethylene raw materials are small-molecule normal alkanes, and reforming raw materials are monocyclic cycloalkanes and aromatics. Through research, the inventors found that by subjecting the coker light distillate oil raw material to the shape-selective cracking of straight-chain alkanes and the selective hydrocracking of long side chains on isoparaffins or cyclic hydrocarbons in sequence, and trying to retain monocyclic cyclic hydrocarbons as much as possible, small-molecule normal alkanes can be generated with high selectivity, so as to efficiently enrich small-molecule normal alkanes in the light 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. In this way, the purpose of greatly improving the yields of chemical raw materials (i.e., light olefin raw materials and reforming raw materials) and the quality of light olefin raw materials and reforming raw materials can be achieved, and thus the present invention is completed.

[0039] Compared with the prior art, the present invention has the following beneficial technical effects:

[0040] (1) In the method for producing chemical raw materials by combining coking and hydrocracking in the present invention, a lower recycle ratio is adopted in the delayed coking reaction zone to increase the yield of light distillate oil in the coking products. By controlling the mass content of bicyclic aromatics in the coker light distillate oil, the content of C9 + cyclic hydrocarbons in the raw material is increased, especially the content of C9 + monocyclic cyclic hydrocarbons, while preventing bicyclic aromatics with higher hydrocracking difficulty from entering the raw material. Then, through hydrocracking, C9 + cyclic hydrocarbons are converted into C6-C9 cyclic hydrocarbons, the final boiling point of the reforming raw material is increased, and the distillation range of the reforming raw material is broadened, which can not only increase the yield of chemical raw materials; at the same time, the aromatic content in the coker light distillate oil is increased, and through hydrocracking, heavy naphtha with a higher aromatic enrichment degree is produced, while increasing the yield of ethylene raw materials.

[0041] (2) The coker light distillate oil first contacts with a shape-selective cracking catalyst (the first hydrocracking catalyst) to carry out a chain-breaking reaction on straight-chain hydrocarbons, and by controlling the content of C7 + normal hydrocarbons in the effluent of the shape-selective cracking reaction within a certain range, it is ensured that the straight-chain hydrocarbons are enriched in light naphtha and gas products after the cracking reaction. Then, through hydrocracking, the isoparaffins are selectively chain-broken, so that the alkanes and cyclic hydrocarbons in the coker light distillate oil are efficiently separated.

[0042] (3) The cyclic hydrocarbons in the hydrocracking product heavy naphtha have a high enrichment degree and a low alkane content. Using this as the catalytic reforming raw material, the catalytic reforming unit only needs to adopt two reaction zones of six-membered ring dehydrogenation and five-membered ring isomerization dehydrogenation, and cancel the alkane cyclization reaction zone, greatly reducing the energy consumption of the catalytic reforming unit. At the same time, since the hydrocracking reaction follows the carbocation reaction mechanism, the side-chain breaking reaction of cyclic hydrocarbons above C9 can be selectively carried out, so that the C6-C8 cyclic hydrocarbons in the product have a high enrichment degree. After catalytic reforming and aromatics extraction, the BTX yield can be greatly increased.

[0043] (4) The present invention selectively converts the alkanes in the light coking distillate oil into small - molecule alkanes. This process consumes a certain amount of hydrogen. However, as the light hydrocarbons are used as raw materials for the ethylene plant, their hydrogen production rate is also high, and the lower the carbon number, the higher the hydrogen production rate. Therefore, most of the hydrogen consumed in the hydrogenation process can be recovered after passing through the ethylene plant. At the same time, using light hydrocarbons as ethylene raw materials can significantly increase the yields of ethylene, propylene, and butadiene, and extend the cleaning cycle of the ethylene plant, significantly improving the economic benefits of the plant. Description of the Drawings

[0044] Figure 1 is a schematic process flow diagram of the process method of the present invention;

[0045] Main reference numeral descriptions:

[0046] 1 - Vacuum residue, 2 - Delayed coking reaction zone, 3 - Petroleum coke, 4 - Delayed coking gas effluent, 5 - Fractionating tower, 6 - Coking gas fraction, 7 - Coking light distillate oil, 8 - Coking diesel oil, 9 - Coking wax oil, 10 - Hydrogen, 11 - First hydrocracking reaction zone, 12 - First hydrocracking reaction effluent, 13 - Second hydrocracking reaction zone, 14 - Second hydrocracking reaction effluent, 15 - Separator, 16 - Gas - phase stream rich - hydrogen gas, 17 - Liquid - phase stream, 18 - Fractionating tower, 19 - Gas fraction, 20 - Light naphtha, 21 - Heavy naphtha. Detailed Embodiments

[0047] The functions and effects of the present invention will be further illustrated by the following examples, but the following examples do not limit the method of the present invention.

[0048] In the present invention, unless otherwise specified, % are all mass fractions.

[0049] The overall volumetric space velocity in the examples and comparative examples is the ratio of the fresh feed volume to the total volume of the catalyst.

[0050] The method of the present invention, as Figure 1 shown, includes: The vacuum residue 1 enters the delayed coking reaction zone 2 to obtain petroleum coke 3 and delayed coking gas effluent 4. The delayed coking gas effluent 4 enters the fractionating tower 5 to be separated into coking gas fraction 6, coking light distillate oil 7, coking diesel oil 8, and coking wax oil 9. The coking light distillate oil 7 is mixed with hydrogen 10 and enters the first hydrocracking reaction zone 11 for the first hydrocracking reaction. The first hydrocracking reaction effluent 12 enters the second hydrocracking reaction zone 13 for the second hydrocracking reaction. The second hydrocracking reaction effluent 14 enters the separator 15. The separated gas - phase stream rich - hydrogen gas 16 is recycled, and the liquid - phase stream 17 enters the fractionating tower 18 to be fractionated into gas fraction 19, light naphtha 20, and heavy naphtha 21.

[0051] 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, and Cat-A3. 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.

[0052] In the present invention, the second hydrocracking catalyst in each example is represented by Cat-B plus a number, such as Cat-B1 and Cat-B2. The physicochemical properties of the catalyst are shown in Table 2. The second hydrocracking catalyst in each example is prepared by a conventional active metal saturation impregnation method. Among them, the properties of the Beta zeolite used in Cat-B1 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 Cat-B2 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 physicochemical properties of the obtained catalyst are shown in Table 2.

[0053] In the present invention, the feedstock oil in each example uses vacuum residue as the feedstock, and its main properties are shown in Table 3.

[0054] In the present invention, the ethylene feedstock in each example refers to ethane, propane, butane, and light naphtha obtained in step (3). Ethane, propane, butane, and light naphtha can be directly used as feedstocks for steam cracking to produce ethylene.

[0055] In the present invention, the distillation range of light naphtha is the liquid component with a boiling point less than 60 °C, and the distillation range of heavy naphtha is 60 - 175 °C.

[0056] 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). 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).

[0057] Example 1

[0058] This example adopts the following Figure 1 process, including:

[0059] (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, coker diesel, and coker wax oil;

[0060] (2) The coker light distillate oil obtained in step (1) is mixed with hydrogen and successively enters the first hydrocracking reaction zone and the second hydrocracking reaction zone; the first hydrocracking reaction zone is filled with the shape-selective cracking catalyst Cat-A1; the second hydrocracking reaction zone is filled with the hydrocracking catalyst Cat-B1; in step (2), the mass content of C7 normal paraffins in the effluent from the first hydrocracking reaction is controlled + to be 1%.

[0061] (3) The effluent from the second hydrocracking reaction zone in step (2) is subjected to gas-liquid separation into a gas-phase stream and a liquid-phase stream. The gas-phase stream is recycled, and the liquid-phase stream enters a fractionating tower, where gas fractions, light naphtha, and heavy naphtha are fractionated.

[0062] In this example, the process conditions and the hydrotreating effect are shown in Table 5.

[0063] Example 2

[0064] This example adopts the following Figure 1 process, including:

[0065] (1) The vacuum residue enters the delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and a gas-phase effluent; the gas-phase effluent enters a fractionating tower to obtain coker dry gas, coker light distillate oil, coker diesel, and coker wax oil;

[0066] (2) The coker light distillate oil obtained in step (1) is mixed with hydrogen and successively enters the first hydrocracking reaction zone and the second hydrocracking reaction zone; the first hydrocracking reaction zone is filled with the shape-selective cracking catalyst Cat-A2; the second hydrocracking reaction zone is filled with the hydrocracking catalyst Cat-B2; in step (2), the mass content of C7 normal paraffins in the effluent from the first hydrocracking reaction is controlled + to be 2%.

[0067] (3) The effluent from the second hydrocracking reaction zone in step (2) is subjected to gas-liquid separation into a gas-phase stream and a liquid-phase stream. The gas-phase stream is recycled, and the liquid-phase stream enters a fractionating tower, where gas fractions, light naphtha, and heavy naphtha are fractionated.

[0068] In this example, the process conditions and the hydrotreating effect are shown in Table 5.

[0069] Example 3

[0070] This example adopts the following Figure 1 process, including:

[0071] (1) The vacuum residue enters the delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and a gas-phase effluent; the gas-phase effluent enters a fractionating tower to obtain coker dry gas, coker light distillate oil, coker diesel, and coker wax oil;

[0072] (2) The coker light distillate oil obtained in step (1) is mixed with hydrogen and successively enters the first hydrocracking reaction zone and the second hydrocracking reaction zone; the first hydrocracking reaction zone is filled with the shape-selective cracking catalyst Cat-A3; the second hydrocracking reaction zone is filled with the hydrocracking catalyst Cat-B1; in step (2), the mass content of C7 + n-paraffin in the effluent from the first hydrocracking reaction is 4%.

[0073] (3) The effluent from the second hydrocracking reaction zone in step (2) is separated into a gas-phase stream and a liquid-phase stream by gas-liquid separation. The gas-phase stream is recycled, and the liquid-phase stream enters the fractionating tower, where gas fractions, light naphtha, and heavy naphtha are fractionated.

[0074] In this example, the process conditions and the hydrotreating effect are shown in Table 5.

[0075] Example 4

[0076] The first hydrocracking reaction zone is filled with the same first hydrocracking catalyst Cat-A1 as in Example 1.

[0077] The second hydrocracking reaction zone is filled with the second hydrocracking catalyst Cat-B2.

[0078] This example adopts the following Figure 1 process, including:

[0079] (1) The vacuum residue enters the delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and a gas-phase effluent; the gas-phase effluent enters the fractionating tower to obtain coker dry gas, coker light distillate oil, coker diesel oil, and coker wax oil;

[0080] (2) The coker light distillate oil obtained in step (1) is mixed with hydrogen and successively enters the first hydrocracking reaction zone and the second hydrocracking reaction zone; the first hydrocracking reaction zone is filled with the shape-selective cracking catalyst Cat-A1; the second hydrocracking reaction zone is filled with the hydrocracking catalyst Cat-B2; in step (2), the mass content of C7 + n-paraffin in the effluent from the first hydrocracking reaction is 1%.

[0081] (3) The effluent from the second hydrocracking reaction zone in step (2) is separated into a gas-phase stream and a liquid-phase stream by gas-liquid separation. The gas-phase stream is recycled, and the liquid-phase stream enters the fractionating tower, where gas fractions, light naphtha, and heavy naphtha are fractionated.

[0082] In this example, the process conditions and the hydrotreating effect are shown in Table 5.

[0083] Comparative Example 1

[0084] The difference from Example 1 is that the coker light distillate oil directly enters the second hydrocracking reaction zone and reacts with the Cat-B1 catalyst.

[0085] In this example, the process conditions and the hydrogenation effect are shown in Table 5.

[0086] Comparative Example 2

[0087] The difference from Example 1 is that in step (2), the content of C7 normal paraffin in the first hydrocracking product is controlled to be 6%. + The content of C7 normal paraffin in the first hydrocracking product is 6%.

[0088] In this example, the process conditions and the hydrogenation effect are shown in Table 5.

[0089] Comparative Example 3

[0090] The difference from Example 3 is that the catalyst Cat-B2 is loaded in the first hydrocracking reaction zone.

[0091] In this example, the process conditions and the hydrogenation effect are shown in Table 5.

[0092] Comparative Example 4

[0093] The difference from Example 1 is that the mass content of diaromatics in the coker light distillate oil is 2.3%.

[0094] In this example, the process conditions and the hydrogenation effect are shown in Table 5.

[0095] Table 1 Physicochemical properties of the first hydrocracking catalyst

[0096]

[0097] Table 2 Physicochemical properties of the second hydrocracking catalyst

[0098]

[0099]

[0100] Table 3 Main properties of the raw materials

[0101] Raw oil name 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

[0102] Table 4 Delayed coking process conditions and main properties of coker light distillate oil

[0103]

[0104] Continued Table 4

[0105]

[0106]

[0107] Table 5 Hydrogenation effect

[0108]

[0109] Continued Table 5

[0110]

[0111]

[0112] 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 solution 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 combined production of chemical raw materials by coking and hydrocracking, the method comprising: (1) Feeding coking feedstock oil into a delayed coking reaction zone for thermal cracking reaction to obtain petroleum coke and gaseous effluent; The gaseous effluent is fractionated to obtain coking light distillate oil; wherein, the mass content of bicyclic aromatic hydrocarbons in the coking light distillate oil is 0.1% - 1.0%; (2) In the presence of hydrogen, the coking light distillate oil obtained in step (1) enters the first hydrocracking reaction zone to selectively crack the n-alkanes in the hydrocarbon oil feedstock, obtaining a first hydrocracking product; wherein, in the first hydrocracking product, the mass content of C7 + n-alkanes is controlled to be 0.1% to 5.0%; (3) In the presence of hydrogen, the first hydrocracking product enters a second hydrocracking reaction zone to obtain a second hydrocracking product containing monocyclic cyclic hydrocarbons; (4) The second hydrocracking product is separated and fractionated to obtain gas fraction, light naphtha, and heavy naphtha; The first hydrocracking reaction zone is filled with a first hydrocracking catalyst, and the second hydrocracking reaction zone is filled with a second hydrocracking catalyst; In step (2), the first hydrocracking catalyst comprises an active metal component and a carrier; the carrier comprises 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 comprises 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 the Group VIB metal in terms of oxide is 5.0% - 15.0%, the content of the Group VIII metal in terms of oxide is 2.0% - 5.0%, and the content of the carrier is 80.0% - 93.0%; in the carrier of the first hydrocracking catalyst, based on the weight of the carrier, the content of the binder is 8% - 60%, and the content of the molecular sieve is 40% - 92%; In step (3), the second hydrocracking catalyst has the function of selectively cracking the side chains of isoparaffins or cyclic hydrocarbons and retaining monocyclic cyclic hydrocarbons; The second hydrocracking catalyst comprises a cracking component, a hydrogenation component, and a binder; the cracking component comprises at least one of Beta molecular sieve and Y molecular sieve; In step (3), for the second hydrocracking catalyst, based on the weight of the second hydrocracking catalyst, the content of the hydrogenation component in terms of oxide is 5wt% - 40wt%; the content of the cracking component is 20wt% - 80wt%; the content of the binder is 5wt% - 75wt%; The chemical raw materials include ethane, propane, butane, light naphtha, and heavy naphtha, wherein, heavy naphtha is used as a reforming feedstock to produce BTX, and ethane, propane, butane, and light naphtha are used as feedstocks for producing low-carbon olefins.

2. The method according to claim 1, wherein In step (1), the mass content of bicyclic aromatic hydrocarbons in the coking light distillate oil is 0.2% - 0.6%.

3. The method according to claim 1, wherein In step (2), in the first hydrocracking product, the mass content of C7 + n-alkanes is controlled to be 1.0% - 4.0%.

4. The method according to claim 1, characterized in that The coking feedstock oil is a heavy oil with an initial boiling point greater than 350 °C, and is selected from one or several of atmospheric residue, vacuum residue, visbreaking residue, heavy deasphalted oil, catalytic cracking slurry, heavy oil, topped crude oil, shale oil, and coal liquefaction oil.

5. The method according to claim 4, wherein The coking feedstock oil is vacuum residue; the initial boiling point of the vacuum residue is 420°C to 550°C; the sulfur mass content is 2% to 10%; the nitrogen mass content is 0.2% to 1.0%; the metal content is 100 mg / kg to 500 mg / kg.

6. The method according to claim 5, wherein The initial boiling point of the vacuum residue is 450°C to 500°C; the sulfur mass content is 4% to 8%; the nitrogen mass content is 0.3% to 0.5%; the metal content is 200 mg / kg to 300 mg / kg.

7. The method according to claim 1, wherein The temperature of the delayed coking reaction zone is 480 to 520°C; the operating pressure is 0.1 MPa to 2 MPa; the recycle ratio is 0.1 to 0.5, and the recycle ratio is the mass ratio of the coker gas oil fraction to the coking feedstock oil.

8. The method according to claim 1, characterized in that The temperature of the delayed coking reaction zone is 490 to 505°C; the operating pressure is 0.2 MPa to 0.5 MPa; the recycle ratio is 0.2 to 0.4, and the recycle ratio is the mass ratio of the coker gas oil fraction to the coking feedstock oil.

9. The method according to claim 1, characterized in that, The initial boiling point of the coker light distillate oil is 50°C to 80°C, and the final boiling point is 190°C to 240°C.

10. The method according to claim 1, characterized in that, The initial boiling point of the coker light distillate oil is 60°C to 70°C, and the final boiling point is 200°C to 220°C.

11. The method according to claim 1, characterized in that, 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.

12. The method according to claim 1, wherein In the second hydrocracking catalyst in step (3), based on the weight of the second hydrocracking catalyst, the content of the hydrogenation component in terms of oxide is 10 wt% to 20 wt%; the content of the cracking component is 30 wt% to 70 wt%; the content of the binder is 10 wt% to 50 wt%.

13. The method according to claim 1, characterized in that In step (2), the reaction conditions of the first hydrocracking reaction are as follows: The reaction pressure is 1.0 to 5.0 MPa; The average reaction temperature is 250 to 450°C; The hourly space velocity of the liquid is 0.1~15.0 h -1 ; The hydrogen-oil volume ratio is 100:1 to 2500:

1.

14. The method according to claim 1, characterized in that In step (2), the reaction conditions of the first hydrocracking reaction are as follows: The reaction pressure is 2.0 to 4.0 MPa; The average reaction temperature is 300 to 400°C; The hourly space velocity of the liquid is 1.0~5.0 h -1 ; The hydrogen-oil volume ratio is 400:1 to 2000:

1.

15. The method according to claim 1, wherein In step (3), the reaction conditions of the second hydrocracking reaction are as follows: The reaction pressure is 1.0 to 5.0 MPa; The average reaction temperature is 250 to 450°C; The hourly space velocity of the liquid is 0.1~15.0 h -1 ; The hydrogen-oil volume ratio is 100:1 to 2500:

1.

16. The method according to claim 1, characterized in that, In step (3), the reaction conditions of the second hydrocracking reaction are as follows: The reaction pressure is 2.0 to 4.0 MPa; The average reaction temperature is 300 to 400°C; The hourly space velocity of the liquid is 1.0 to 5.0 h -1 ; The hydrogen-oil volume ratio is 400:1 to 2000:

1.

17. The method according to claim 1, wherein The ratio of the mass of C6-C8 monocyclic cyclic hydrocarbons in the second hydrocracking product in step (3) to the total mass of cyclic hydrocarbons in the coker light distillate oil feedstock is 0.40 to 0.

80.

18. The method according to claim 1, wherein The ratio of the mass of C6-C8 monocyclic cyclic hydrocarbons in the second hydrocracking product in step (3) to the total mass of cyclic hydrocarbons in the coker light distillate oil feedstock is 0.49 to 0.62.

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