Method and system for comprehensive utilization of catalytic slurry oil

Abstract

This invention discloses a method and system for the comprehensive utilization of catalytic oil slurry. The method first involves hydrogenating the catalytic oil slurry. The separated hydrogenated tail oil then undergoes a cracking reaction. The cracking products are treated with an extractant. After separation, the extract phase is processed by recovering the extractant to obtain aromatic oil. The heavy fraction obtained from the separation of the aromatic oil enters a coking reaction zone, where it reacts to yield oil gas and needle coke products. A comprehensive utilization system for catalytic oil slurry using the above method is also provided. The method and system of this invention can improve the mechanical strength of the obtained needle coke, effectively improve the microstructure of the needle coke, and obtain high-quality needle coke.

Description

Technical Field

[0001] This invention belongs to the field of catalytic oil slurry treatment technology, and in particular relates to a method and system for preparing oil-based needle coke from catalytic oil slurry. Background Technology

[0002] Catalytic slurry contains a large amount of aromatics and is a high-quality feedstock for producing oil-based needle coke. As the sulfur content of crude oil gradually increases, the sulfur content of catalytic slurry also increases. Low-sulfur catalytic slurry resources are scarce, and catalytic slurry with a sulfur content >0.5 wt% has become the main source of feedstock for needle coke production. To address the problem of high sulfur content in existing catalytic slurry, a hydrotreating process is typically used to remove some of the sulfur, reducing the sulfur content of the catalytic slurry to below 0.5 wt%, or even below 0.4 wt%.

[0003] CN110511785A discloses a method for preparing needle coke feedstock by catalytic oil slurry. The specific steps are as follows: adding low molecular weight n-alkanes to the oil slurry, deasphalting to obtain the supernatant, and then extracting and desolidifying the supernatant to obtain aromatic oil. The aromatic oil is then subjected to hydrodesulfurization treatment to obtain the needle coke feedstock.

[0004] CN106147835A discloses a combined method for separating catalytic cracking slurry and preparing oil-based needle coke. The method uses C3-C5 light hydrocarbon fractions as extraction solvents to perform subcritical or supercritical extraction on the catalytic cracking slurry. The obtained extracted oil phase is then processed using supercritical solvent recovery to obtain an extract component. This extract component is used as a raw material for preparing mesophase asphalt, which is then subjected to thermal polycondensation to prepare mesophase asphalt. The mesophase asphalt is then subjected to delayed coking to obtain high-quality oil-based needle coke. When the sulfur content of the catalytic cracking slurry is high, the extracted light component can be first subjected to hydrodesulfurization treatment. The hydrotreated oil is then fractionated to collect the hydrotreated tail oil, which is used as a raw material for preparing mesophase asphalt, and subsequently, needle coke.

[0005] In all the above methods, aromatics are first enriched by extraction, and then impurities such as sulfur are removed by hydrogenation. The resulting low-sulfur catalytic slurry is then used directly as a raw material for the production of needle coke. Summary of the Invention

[0006] During the research process, the applicant discovered that after the catalytic slurry is hydrogenated, the molecular structure of the aromatic hydrocarbons in the catalytic slurry changes. The aromatic hydrocarbons with short side chains are transformed into aromatic hydrocarbons with a large number of alkyl or cycloalkyl side chains. When the hydrogenated slurry is used in the production of needle coke, the molecular reaction state is very different, resulting in a loose structure between the layers of the obtained needle coke product, which affects the mechanical properties of the product.

[0007] To address the shortcomings of existing technologies, this invention provides a method and system for the comprehensive utilization of catalytic oil slurry. On the one hand, the method and system of this invention can improve the mechanical strength of needle coke, effectively improve the microstructure of needle coke, increase the density between the layers, and obtain high-quality needle coke. On the other hand, it can also produce naphtha products as a byproduct.

[0008] The first aspect of this invention provides a method for the comprehensive utilization of catalytic oil slurry, the method comprising the following steps:

[0009] (1) In the presence of hydrogen, the catalytic slurry enters the hydrogenation reaction zone and comes into contact with the hydrogenation catalyst to carry out the hydrogenation reaction. The reaction effluent is separated to obtain gas, naphtha and hydrogenation tail oil.

[0010] (2) The hydrotreated tail oil obtained in step (1) enters the cracking reaction zone for cracking reaction;

[0011] (3) The cracking reaction products obtained in step (2) enter the extraction unit, are processed by contacting the extractant, and are separated to obtain the extract phase and the raffinate phase;

[0012] (4) The extract phase obtained in step (3) enters the extractant recovery unit, and after separation, regenerated extractant and aromatic oil are obtained;

[0013] (5) After separation, the aromatic oil obtained in step (4) is divided into light and heavy fractions. The heavy fraction enters the coking reaction zone and is reacted to obtain oil gas and needle coke products.

[0014] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the catalytic oil slurry in step (1) is preferably purified first. The purification treatment can be one or a combination of several methods such as filtration, centrifugal sedimentation, electrostatic adsorption, and flocculation sedimentation, with filtration being the preferred method. Under normal circumstances, the ash content of the purified catalytic oil slurry is ≤0.01wt%.

[0015] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the sulfur content of the catalytic oil slurry in step (1) is generally higher than 0.5 wt%.

[0016] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the hydrogenation reaction zone in step (1) includes one or more hydrogenation reactors. When two or more hydrogenation reactors are set, there are no particular restrictions on the connection method between the reactors. For example, they can be connected in series and / or in parallel, with series connection being preferred. The hydrogenation reactor can be selected from one or a combination of several of the following: fluidized bed reactor, suspended bed reactor, fixed bed reactor, etc., with fixed bed reactor being preferred.

[0017] Furthermore, in the above-mentioned comprehensive utilization method of catalytic slurry, the hydrogenation catalyst in step (1) can be prepared according to existing methods in the field, or existing commercial catalysts such as the FZC series hydrogenation catalysts developed by the Dalian Petrochemical Research Institute of Sinopec can be used. Generally, the hydrogenation catalyst includes a support and an active component. The support is generally alumina, and the active component is generally an oxide of Group VIB and / or Group VIII metals, such as one or a combination of oxides of metals such as Mo, W, Co, and Ni.

[0018] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the reaction conditions in the hydrogenation reaction zone in step (1) are as follows: the reaction temperature is 300℃~450℃, preferably 340℃~385℃; the reaction pressure is 2MPa~25MPa, preferably 4MPa~8MPa; the hydrogen-to-oil volume ratio is 100~2500, preferably 500~1800; and the liquid hourly space velocity is 0.1h. -1 ~2.0h -1 Preferably 0.6h -1 ~1.2h -1 .

[0019] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the sulfur content of the hydrogenated tail oil in step (1) is not higher than 0.4 wt%, preferably not higher than 0.35 wt%.

[0020] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the cracking reaction zone in step (2) is set up in one or more reactors. The reactor can be at least one of tubular reactor, tower reactor, and tank reactor, with tower reactor being preferred.

[0021] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the reaction conditions in the cracking reaction zone in step (2) are as follows: the reaction temperature is 380℃~520℃, preferably 420℃~490℃; the reaction pressure is 0.1MPa~5MPa, preferably 0.2MPa~1.0MPa; and the residence time is 0.01h~30h, preferably 0.1h~3h. It is further preferred that a carrier gas is introduced during the cracking reaction. The carrier gas can be one or more of water vapor, nitrogen, and inert gases (such as helium, neon, and argon), preferably water vapor; the mass ratio of hydrotreated tail oil to carrier gas is 100:0.1~100:20, preferably 100:1~100:8.

[0022] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the extraction unit in step (3) includes at least one extraction tower, in which the cracking reaction products and the extractant come into contact with each other and are separated. It is preferred to use a countercurrent method for contact. After processing, the extract phase and the raffinate phase are obtained. The raffinate phase can be used as feed for the catalytic cracking unit.

[0023] Furthermore, in the above-mentioned method for comprehensive utilization of catalytic oil slurry, the extractant in step (3) can be selected from one or a mixture of several of furfural, N-methylformamide, N-methylpyrrolidone, dimethyl sulfoxide, etc., preferably furfural. Even further, the mass ratio of the extractant to the cracking reaction product is 1:1 to 5:1, preferably 1.5:1 to 2.5:1.

[0024] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the extractant recovery unit in step (4) is equipped with at least one extractant separation tower. The extractant phase is separated in the extractant separation tower. After the separation is completed, regenerated extractant and aromatic oil are obtained. The regenerated extractant is recycled back to the extraction unit for reuse.

[0025] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the light fraction obtained after separation of aromatic oil in step (5) can be discharged from the device or enter the hydrogenation reaction zone for processing together with the catalytic oil slurry, preferably entering the hydrogenation reaction zone for processing together with the catalytic oil slurry.

[0026] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the 5% distillation temperature of the heavy fraction in step (5) is 300℃~400℃, preferably 350℃~380℃.

[0027] Furthermore, in the above-mentioned comprehensive utilization method of catalytic oil slurry, the coking reaction zone in step (5) is generally equipped with at least one heating furnace and at least two coke towers, and at least one coke tower is always kept in the reaction stage and at least one coke tower is in the decoking stage. The specific control conditions of the coking reaction zone are as follows: the outlet temperature of the heating furnace is 410℃~550℃, preferably 440℃~520℃, and the heating rate is generally controlled at 0.5℃ / h~30℃ / h, preferably 3℃ / h~8℃ / h; the top pressure of the coke tower is 0.01MPa~2.5MPa, preferably 0.2MPa~1.3MPa, and can be operated under constant pressure or variable pressure. When using variable pressure operation, the variable pressure rate can generally be controlled at 0.1MPa / h~5MPa / h; the reaction cycle is 10h~72h, preferably 32h~54h.

[0028] A second aspect of the present invention provides a comprehensive utilization system for catalytic oil slurry, comprising:

[0029] The hydrogenation reaction zone is used to receive hydrogen and catalytic oil slurry. The catalytic oil slurry enters the hydrogenation reaction zone and comes into contact with hydrogen and hydrogenation catalyst to carry out the hydrogenation reaction.

[0030] The separation unit is used to receive and separate the reaction effluent from the hydrogenation reaction zone, and the separated products are gas, naphtha and hydrogenation tail oil.

[0031] The cracking reaction zone is used to receive hydrotreated tail oil from the hydrotreating reaction zone;

[0032] An extraction unit is used to receive the extractant and the cracking reaction products from the cracking reaction zone, and to separate them to obtain the extract phase and the raffinate phase;

[0033] The extractant recovery unit is used to receive the extract phase from the extraction unit, and after separation, obtain the regenerated extractant and aromatic oil.

[0034] The fractionation unit is used to receive aromatic oil from the extractant recovery unit and separate it into light and heavy fractions.

[0035] The coking reaction zone is used to receive heavy fractions from the fractionation unit, which react to produce oil and gas and needle coke.

[0036] Furthermore, in the aforementioned catalytic slurry comprehensive utilization system, the hydrogenation reaction zone includes one or more hydrogenation reactors. When two or more hydrogenation reactors are installed, there are no particular restrictions on the connection method between the reactors; they can be connected in series and / or parallel, but series connection is generally used. The hydrogenation reactor can be selected from one or a combination of several of the following: fluidized bed reactor, suspended bed reactor, fixed bed reactor, etc., with a fixed bed reactor being preferred.

[0037] Furthermore, in the above-mentioned catalytic oil slurry comprehensive utilization system, the separation unit generally includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, and a cold low-pressure separator, and may also optionally include a stripping tower and a fractionation tower.

[0038] Furthermore, in the above-mentioned catalytic slurry comprehensive utilization system, the cracking reaction zone is set up with one or more reactors, and the reactor can be at least one of tubular reactor, tower reactor, and tank reactor, with tower reactor being preferred.

[0039] Furthermore, in the above-mentioned catalytic oil slurry comprehensive utilization system, the extraction unit includes at least one extraction tower, in which the cracking reaction products and the extractant come into contact with each other and are separated.

[0040] Furthermore, in the above-mentioned catalytic oil slurry comprehensive utilization system, the extractant recovery unit is equipped with at least one extractant separation tower. The extractant phase is separated in the extractant separation tower. After the separation is completed, regenerated extractant and aromatic oil are obtained. The regenerated extractant is recycled back to the extraction unit for reuse.

[0041] Furthermore, in the above-mentioned catalytic slurry comprehensive utilization system, the coking reaction zone is generally equipped with at least one heating furnace and at least two coke towers, and at least one coke tower is always kept in the reaction stage and at least one coke tower is in the decoking stage.

[0042] Furthermore, in the aforementioned catalytic oil slurry comprehensive utilization system, the raffinate phase can be sent to the catalytic cracking unit for treatment via pipeline.

[0043] Furthermore, in the aforementioned catalytic oil slurry comprehensive utilization system, the light fraction is discharged through a pipeline or enters the hydrogenation reaction zone through a pipeline to be processed together with the catalytic oil slurry, preferably entering the hydrogenation reaction zone to be processed together with the catalytic oil slurry.

[0044] Compared with existing technologies, the comprehensive utilization method and system for catalytic oil slurry provided by this invention have the following advantages:

[0045] (1) The catalytic slurry comprehensive utilization method provided by this invention examines and optimizes the molecular structure of needle coke feedstock at the microscopic level. During hydrodesulfurization, the catalytic slurry will inevitably saturate some aromatic rings. When used directly as feedstock to prepare needle coke, these aromatics with saturated side chains will undergo chain breaking or aromatization reactions. The small molecules generated will escape and disturb the reaction system, which is not conducive to the liquid phase carbonization reaction and leads to incomplete development of the intermediate phase, directly affecting the microstructure of needle coke. In addition, the simultaneous occurrence of aromatic side chain breaking reaction and condensation reaction will affect the planarity of the condensed macromolecules, resulting in a loose lamellar structure of needle coke and a decrease in mechanical properties. This invention moves the side chain breaking reaction and cycloalkyl aromatization reaction to the cracking reaction zone, ensuring from the molecular structure perspective that the aromatics in the cracking products are all aromatics with a small amount of short side chains, which are more suitable as feedstock for the production of needle coke.

[0046] (2) In the comprehensive utilization method of catalytic oil slurry provided by the present invention, after the catalytic oil slurry undergoes hydrogenation treatment and cracking reaction, the saturated hydrocarbon content will increase and the relative aromatic hydrocarbon content will decrease. Furthermore, by combining with the extraction process, the aromatic hydrocarbons in the extraction phase are enriched, and the aromatic hydrocarbon content in the material is increased again, thus making up for the adverse effects of hydrogenation treatment and cracking reaction.

[0047] (3) The comprehensive utilization method of catalytic oil slurry provided by the present invention makes full use of various structural aromatics in catalytic oil slurry, and produces high-value naphtha products as by-products while obtaining high-quality needle coke products. After hydrotreating, cracking reaction, extraction and fractionation, the heavy fraction is used as raw material for producing needle coke, and the light fraction is mainly composed of monocyclic and bicyclic aromatics. The light fraction is returned to the hydrotreating reaction zone to continue the reaction with the catalytic oil slurry, which will produce high-value naphtha products as by-products. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the comprehensive utilization method of catalytic oil slurry according to the present invention. Detailed Implementation

[0049] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0050] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0051] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (e.g., rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0052] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0053] In this document, all numeric values ​​of parameters (e.g., quantity or condition) should be understood to be modified by the term “about” in all cases, regardless of whether “about” actually appears before the numeric value.

[0054] In this paper, the sulfur content was determined by the GB / T 24526 method; the Hastelloy grindability index was determined by the GB / T 2565 method; the tap density sample was prepared according to the requirements of GB / T 1997, and at least 150g of 1mm~2mm particles were screened and determined by the GB / T21354 method; the particle strength was determined by the method in Appendix B of T / ZGTS 002.

[0055] like Figure 1As shown, the process flow of the comprehensive utilization method of catalytic oil slurry provided by the present invention is as follows: In the presence of hydrogen 2, the purified catalytic oil slurry 1 enters the hydrogenation reaction zone 3 and contacts the hydrogenation catalyst to carry out a hydrogenation reaction. The reaction effluent 4 enters the separation unit 5 for separation, and after separation, gas 21, naphtha 6, and hydrogenated tail oil 7 are obtained. The obtained hydrogenated tail oil 7 enters the cracking reaction zone 9 for a cracking reaction. During the cracking reaction, carrier gas 8 can also be introduced. The obtained cracking reaction product 10 enters the extraction unit 12 and is processed by contacting the extractant 11. After separation, extract phase 14 and... Raffinate phase 13; wherein raffinate phase 13 can be processed in the catalytic cracking unit; extract phase 14 enters the extractant recovery unit 15, and after separation, regenerated extractant 16 and aromatic oil 17 are obtained; regenerated extractant 16 is returned to the extraction unit 12 for use, and aromatic oil 17 is sent to the fractionation unit 18 to be separated into light fraction 19 and heavy fraction 20, wherein heavy fraction 20 enters the coking reaction zone 22A / 22B, and after reaction, oil gas 24 and needle coke product 23 are obtained, and light fraction 19 is discharged from the unit, or mixed with purified catalytic slurry 1 and entered into the hydrogenation reaction zone 3 for further reaction.

[0056] The properties of the purified catalytic slurry used in the embodiments and comparative examples of this invention are shown in Table 1. The hydrogenation catalyst used is the FZC-34BT hydrogenation catalyst developed by the Dalian Research Institute of Petrochemical Technology, Sinopec. Water vapor is introduced as the carrier gas during the cracking reaction.

[0057] Example 1

[0058] Example 1 uses the method provided by this invention. The purified catalytic slurry enters the hydrogenation reaction zone and contacts the hydrogenation catalyst to carry out the hydrogenation reaction. The hydrogenation reaction conditions are: reaction temperature of 372°C, reaction pressure of 5.5 MPa, hydrogen-to-oil volume ratio of 1000, and liquid hourly space velocity of 0.87 h⁻¹. -1 After separating the gas and naphtha from the hydrotreating effluent, the hydrotreating tail oil and water vapor enter the cracking reaction zone at a mass ratio of 100:3. The cracking reaction conditions are: reaction temperature 468℃, reaction pressure 0.6MPa, and residence time 1h. The cracking products enter the extraction unit and are treated with furfural extractant at a mass ratio of 1:2. The resulting aromatic-rich oil is sent to the fractionation unit to separate light and heavy fractions, with the heavy fraction (5%) distilling at 363℃. The heavy fraction oil enters the coking reaction zone. The coking reaction conditions are: furnace outlet temperature 445℃~510℃, heating rate 5℃ / h, coke tower top pressure 0.85MPa, constant pressure operation, and reaction cycle 46h.

[0059] Example 2

[0060] Example 2 uses the method provided by this invention, and the operating conditions are basically the same as those in Example 1. The difference lies in the hydrogenation reaction conditions: reaction temperature of 370°C, reaction pressure of 5.8 MPa, hydrogen-to-oil volume ratio of 1000, and liquid hourly space velocity of 0.82 h⁻¹. -1 The cracking reaction conditions were: reaction temperature 464℃, reaction pressure 0.5MPa, and residence time 1.5h.

[0061] Example 3

[0062] Example 3 uses the method provided by this invention, and the operating conditions are basically the same as those in Example 1. The difference lies in the hydrogenation reaction conditions: reaction temperature of 368°C, reaction pressure of 5.9 MPa, hydrogen-to-oil volume ratio of 1000, and liquid hourly space velocity of 0.80 h⁻¹. -1 The cracking reaction conditions were: a reaction temperature of 464℃, a reaction pressure of 0.45MPa, and a residence time of 1.8h.

[0063] Comparative Example 1

[0064] Comparative Example 1 uses existing technology for production. The purified catalytic slurry enters the extraction unit and is treated with furfural as an extractant at a mass ratio of 1:2. The resulting aromatic-rich oil is sent to the fractionation unit to separate light and heavy fractions, with the heavy fraction (5%) distilling at 360°C. The heavy fraction oil enters the hydrogenation reaction zone and undergoes a hydrogenation reaction with a hydrogenation catalyst. The hydrogenation reaction conditions are: reaction temperature 372°C, reaction pressure 5.5 MPa, hydrogen-to-oil volume ratio 1000, and liquid hourly space velocity 0.88 h⁻¹. -1 After separating the gas and naphtha from the hydrotreating effluent, the hydrotreating tail oil enters the coking reaction zone. The coking reaction conditions are: furnace outlet temperature of 445℃~510℃, heating rate of 5℃ / h, coke tower top pressure of 0.85MPa, constant pressure operation, and reaction cycle of 46h.

[0065] Comparative Example 2

[0066] Comparative Example 2 was produced using existing technology, with operating conditions essentially the same as Comparative Example 1. The difference was that the aromatic-rich oil first entered the hydrogenation reaction zone. The hydrogenation reaction conditions were: reaction temperature 369℃, reaction pressure 5.8MPa, hydrogen-to-oil volume ratio 1000, and liquid hourly space velocity 0.81h⁻¹. -1 The resulting hydrotreated tail oil is sent to a fractionation unit to separate light and heavy fractions, with 5% of the heavy fraction distilled at 369°C. The heavy fraction oil then enters the coking reaction zone.

[0067] The needle coke (raw coke) obtained in the above examples and comparative examples was tested for sulfur content and Hastelloy grindability index; the needle coke was calcined at 1350℃ to obtain cooked coke, and the tap density and particle strength of the cooked coke were tested. The reaction results are shown in Table 2.

[0068] Table 1. Properties of Raw Materials

[0069] project Catalytic slurry Sulfur content, wt% 1.03 Ash content, wt% 0.006

[0070] Table 2 Analysis Results

[0071]

[0072] As can be seen from Table 2, the needle coke prepared by the method of the present invention has a lower Hastelloy grindability index and higher particle strength, indicating that the needle coke has better mechanical strength. When the sulfur content of the needle coke is comparable, the mechanical strength of the needle coke prepared in Example 1 is significantly better than that of the needle coke prepared in Comparative Example 1.

Claims

1. A method for comprehensive utilization of catalytic oil slurry, the method comprising the following steps: (1) In the presence of hydrogen, the catalytic slurry enters the hydrogenation reaction zone and comes into contact with the hydrogenation catalyst to carry out the hydrogenation reaction. The reaction effluent is separated to obtain gas, naphtha and hydrogenation tail oil. (2) The hydrotreated tail oil obtained in step (1) enters the cracking reaction zone for cracking reaction; the reaction conditions in the cracking reaction zone are: reaction temperature of 380℃~520℃, reaction pressure of 0.1MPa~5MPa, and residence time of 0.01h~30h. (3) The cracking reaction products obtained in step (2) enter the extraction unit, are processed by contacting the extractant, and are separated to obtain the extract phase and the raffinate phase; (4) The extract phase obtained in step (3) enters the extractant recovery unit, and after separation, regenerated extractant and aromatic oil are obtained; (5) After separation, the aromatic oil obtained in step (4) is divided into light and heavy fractions. The heavy fraction enters the coking reaction zone and is reacted to obtain oil gas and needle coke products.

2. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: In step (1), the catalytic slurry is first purified. The purification process uses one or more of the following methods: filtration, centrifugal sedimentation, electrostatic adsorption, and flocculation sedimentation. The ash content of the purified catalytic slurry is ≤0.01wt%.

3. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: In step (1), the catalytic slurry is first purified by filtration.

4. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The reaction conditions in the hydrogenation reaction zone in step (1) are as follows: reaction temperature 300℃~450℃, reaction pressure 2MPa~25MPa, hydrogen-to-oil volume ratio 100~2500, and liquid hourly space velocity 0.1h. -1 ~2.0h -1 .

5. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The reaction conditions in the hydrogenation reaction zone in step (1) are as follows: reaction temperature 340℃~385℃, reaction pressure 4MPa~8MPa, hydrogen-to-oil volume ratio 500~1800, and liquid hourly space velocity 0.6h. -1 ~1.2h -1 .

6. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The sulfur content of the hydrotreated tail oil in step (1) shall not exceed 0.4 wt%.

7. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The sulfur content of the hydrotreated tail oil in step (1) shall not exceed 0.35 wt%.

8. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The reaction conditions in the cracking reaction zone in step (2) are: reaction temperature of 420℃~490℃, reaction pressure of 0.2MPa~1.0MPa, and residence time of 0.1h~3h.

9. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: During the cracking reaction, a carrier gas is introduced, which is one or more of water vapor, nitrogen, and inert gases.

10. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: During the cracking reaction, a carrier gas, which is water vapor, is introduced.

11. The method for comprehensive utilization of catalytic oil slurry according to claim 9 or 10, characterized in that: The mass ratio of hydrotreated tail oil to carrier gas is 100:0.1 to 100:

20.

12. The method for comprehensive utilization of catalytic oil slurry according to claim 9 or 10, characterized in that: The mass ratio of hydrotreated tail oil to carrier gas is 100:1 to 100:

8.

13. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The extractant in step (3) is selected from one or more of furfural, N-methylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

14. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The extractant in step (3) is furfural.

15. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The mass ratio of extractant to cracking reaction product is 1:1 to 5:

1.

16. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The mass ratio of extractant to cracking reaction product is 1.5:1 to 2.5:

1.

17. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: The light fraction obtained after separating the aromatic oil in step (5) is discharged from the device or enters the hydrogenation reaction zone for processing together with the catalytic oil slurry.

18. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: In step (5), the light fraction obtained after separating the aromatic oil enters the hydrogenation reaction zone and is processed together with the catalytic oil slurry.

19. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: In step (5), the 5% distillation temperature of the heavy fraction is 300℃~400℃.

20. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: In step (5), the 5% distillation temperature of the heavy fraction is 350℃~380℃.

21. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: In step (5), the coking reaction zone is equipped with at least one heating furnace and at least two coke towers, and at least one coke tower is always in the reaction stage and at least one coke tower is in the decoking stage. The outlet temperature of the heating furnace is 410℃~550℃, the top pressure of the coke tower is 0.01MPa~2.5MPa, and the reaction cycle is 10h~72h.

22. The method for comprehensive utilization of catalytic oil slurry according to claim 1, characterized in that: In step (5), the coking reaction zone is equipped with at least one heating furnace and at least two coke towers, and at least one coke tower is always in the reaction stage and at least one coke tower is in the decoking stage. The outlet temperature of the heating furnace is 440℃~520℃, the top pressure of the coke tower is 0.2MPa~1.3MPa, and the reaction cycle is 32h~54h.

23. A catalytic oil slurry comprehensive utilization system for implementing the method of any one of claims 1-22, comprising: The hydrogenation reaction zone is used to receive hydrogen and catalytic oil slurry. The catalytic oil slurry enters the hydrogenation reaction zone and comes into contact with hydrogen and hydrogenation catalyst to carry out the hydrogenation reaction. The separation unit is used to receive and separate the reaction effluent from the hydrogenation reaction zone, and the separated products are gas, naphtha and hydrogenation tail oil. The cracking reaction zone is used to receive hydrotreated tail oil from the hydrotreating reaction zone; An extraction unit is used to receive the extractant and the cracking reaction products from the cracking reaction zone, and to separate them to obtain the extract phase and the raffinate phase; The extractant recovery unit is used to receive the extract phase from the extraction unit, and after separation, obtain the regenerated extractant and aromatic oil. The fractionation unit is used to receive aromatic oil from the extractant recovery unit and separate it into light and heavy fractions. The coking reaction zone is used to receive heavy fractions from the fractionation unit, which react to produce oil and gas and needle coke.

24. The catalytic oil slurry comprehensive utilization system according to claim 23, characterized in that: The hydrogenation reaction zone includes one or more hydrogenation reactors, which are selected from one or more of the following: fluidized bed reactor, suspended bed reactor, and fixed bed reactor.

25. The catalytic oil slurry comprehensive utilization system according to claim 23, characterized in that: The cracking reaction zone is equipped with at least one reactor, which is at least one of a tubular reactor, a tower reactor, and a tank reactor.

26. The catalytic oil slurry comprehensive utilization system according to claim 23, characterized in that: The cracking reaction zone is equipped with at least one reactor, which is a tower reactor.

27. The catalytic oil slurry comprehensive utilization system according to claim 23, characterized in that: The extraction unit includes at least one extraction tower, in which the cracking reaction products and the extractant come into contact with each other and are separated.

28. The catalytic oil slurry comprehensive utilization system according to claim 23, characterized in that: The extractant recovery unit is equipped with at least one extractant separation tower, in which the extractant phase is separated. After separation, regenerated extractant and aromatic oil are obtained, and the regenerated extractant is recycled back to the extraction unit for reuse.

29. The catalytic oil slurry comprehensive utilization system according to claim 23, characterized in that: The coking reaction zone is equipped with at least one heating furnace and at least two coke towers, and at least one coke tower is always in the reaction stage and at least one coke tower is in the decoking stage.

30. The catalytic oil slurry comprehensive utilization system according to claim 23, characterized in that: The raffinate is sent to the catalytic cracking unit via pipeline for processing.

31. The catalytic oil slurry comprehensive utilization system according to claim 23, characterized in that: Light fractions are either discharged from the unit via pipeline or fed into the hydrogenation reaction zone via pipeline for processing together with the catalytic slurry.

32. The catalytic oil slurry comprehensive utilization system according to claim 23, characterized in that: The light fraction is piped into the hydrogenation reaction zone and processed together with the catalytic oil slurry.

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