Ethylene tar hydrotreatment method and treatment system

Abstract

The invention discloses an ethylene tar hydrotreating method. The processing method comprises the following steps: mixing an ethylene tar raw material and hydrogen-containing gas, sequentially passing through a low-temperature hydrogenation reaction zone and a high-temperature hydrogenation reaction zone, and separating to obtain a final liquid-phase product, the reaction temperature of the low-temperature hydrogenation reaction zone is 80-175 DEG C, preferably 100-175 DEG C; and the reaction temperature of the high-temperature hydrogenation reaction zone is 180-380 DEG C, preferably 180-360 DEG C. According to the treatment method, low-temperature and high-temperature two-stage hydrotreating processes are set according to molecular structures and reaction characteristics of olefins in the ethylene tar, so that the olefins in the ethylene tar are removed in a partitioned manner, and the problem that a device is easy to coke in the processing and utilization process of the ethylene tar is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of petrochemical industry, and relates to a method and a processing system for hydrotreating oil products, specifically to a method and a processing system for hydrotreating ethylene tar. Background Art

[0002] Ethylene tar is a high-temperature condensation product during the steam cracking of ethylene raw materials, and its output is about 10wt.% - 15wt.% of the ethylene output. The composition structure of ethylene tar is complex, with high contents of unsaturated hydrocarbons such as aromatics and aromatic olefins, poor oxidation stability and compatibility. From practical processing experience, it is an oil product with high utilization difficulty. With the continuous expansion of domestic ethylene production capacity, how to achieve high-value utilization of ethylene tar has become a difficult problem faced by the petrochemical industry.

[0003] Patent CN106554795A discloses a method for utilizing ethylene tar. The method includes the following steps: mixing Shengli crude oil and ethylene tar evenly and then entering a crude oil distillation unit for distillation. First, gasoline and diesel fractions are cut out by atmospheric distillation, and then diesel, wax oil and residue fractions are cut out by vacuum distillation. Patent CN103773497A discloses a method for increasing fuel oil production. In this method, ethylene tar is fractionated into light fraction and heavy fraction. The heavy fraction is mixed with conventional coking raw materials and subjected to delayed coking to obtain coking products. These coking products and C 9 components from the ethylene unit enter a coking distillation column together, and through distillation, coking gasoline fraction and coking diesel fraction are obtained. The obtained coking gasoline fraction is subjected to hydrorefining, and the coking diesel is mixed with the light fraction of ethylene tar for hydrotreating. The obtained product is separated to obtain gasoline and diesel products. Both of the above two patents perform fractionation treatment on ethylene tar. However, when ethylene tar is directly subjected to atmospheric and vacuum distillation, serious coking phenomena will occur in parts such as the heating furnace, heat exchanger, and the bottom of the distillation column after running for a period of time, resulting in the abnormal operation of the distillation column and the forced shutdown of the entire device.

[0004] Patent CN114540059A discloses a combined process, a combined system for producing needle coke from heavy oil and the needle coke produced thereby. The method includes the following steps: after heavy oil such as ethylene tar is subjected to hydrotreating, it is separated into light and heavy components. The light components enter an electrostatic desolidification device to obtain deashed oil, and the deashed oil then enters a solvent extraction device. The obtained extract oil enters a delayed coking device to produce needle coke. In the method of this invention, ethylene tar is subjected to hydrotreating before cutting to remove the olefins therein. However, the reaction temperature of the hydrotreating is 360 - 400 °C. At this reaction temperature, a large amount of condensation coking reactions will occur in the heavy components, and the difference between the light and heavy components in ethylene tar will further increase, which will cause serious phase separation of ethylene tar with low stability itself and increase the probability of coking and blockage of the device. Summary of the Invention

[0005] Compared with heavy raw materials such as conventional residuum or coker gas oil, ethylene tar contains a large amount of unsaturated olefins. The C=C double bonds will rapidly undergo polycondensation reactions to form coke, resulting in a lower initial coking temperature for ethylene tar. Through in-depth research on the molecular structure and reaction characteristics of ethylene tar, it is found that olefin molecules with different structures have different electron cloud densities, which in turn affect their adsorption and reaction rates on the catalyst surface. From the perspective of adsorption and reaction rates, the olefins contained in ethylene tar can be divided into type I olefins and type II olefins. Among them, type I olefins include polyolefins and a small part of extremely active monoolefins. They have a high electron cloud density, are easy to adsorb and react on the catalyst surface, and are sensitive to temperature. This type of olefin is the fundamental reason for the lower initial coking temperature of ethylene tar; type II olefins refer to most monoolefins. Compared with type I olefins, type II olefins have a low electron cloud density, are not easy to adsorb and react on the catalyst surface, have low temperature sensitivity, and a relatively higher coking temperature. Therefore, during the removal of type I olefins, the reaction temperature needs to be strictly controlled, otherwise severe coking is likely to occur at positions such as the heat exchanger, the inlet of the reactor, or inside the reactor bed layer, affecting the normal operation of the device. When removing type II olefins, the hydrogenation reaction temperature can be set relatively high to improve the performance of the catalyst. The technical solution of the present invention is proposed based on the above findings.

[0006] The present invention provides a hydrogenation treatment method and treatment system for ethylene tar. The treatment method sets a two-stage hydrogenation treatment process of low temperature and high temperature according to the molecular structure and reaction characteristics of olefins in ethylene tar, thereby removing olefins in ethylene tar in zones and solving the problem of easy coking of the device during the processing and utilization of ethylene tar.

[0007] A hydrogenation treatment method for ethylene tar, the treatment method includes the following: the ethylene tar raw material and the hydrogen-containing gas are mixed and then sequentially pass through a low-temperature hydrogenation reaction zone and a high-temperature hydrogenation reaction zone, and finally a liquid product is obtained through separation; the reaction temperature of the low-temperature hydrogenation reaction zone is 80~175°C, preferably 100~175°C; the reaction temperature of the high-temperature hydrogenation reaction zone is 180~380°C, preferably 180~360°C.

[0008] Furthermore, in the above method, by controlling the temperature difference between the low-temperature hydrogenation reaction zone and the high-temperature hydrogenation reaction zone, the olefin content of the final liquid product can be regulated, and thus the use of the liquid product can be regulated.

[0009] Furthermore, in the above method, the temperature difference between the low-temperature hydrogenation reaction zone and the high-temperature hydrogenation reaction zone is 5~85°C, preferably 10~80°C. The olefin content of the final liquid product is regulated to 3.0~9.0 mol%, preferably 4.0~8.0 mol%, and it can be used as a raw material for producing low-sulfur petroleum coke.

[0010] Further, in the above method, the temperature difference between the low-temperature hydrogenation reaction zone and the high-temperature hydrogenation reaction zone is 85-250 °C, preferably 85-220 °C. The olefin content of the final liquid product is adjusted to 0-2.0 mol%, preferably 0-1.0 mol%, which can be used as a blending component for low-sulfur marine fuel.

[0011] Further, in the above method, a first hydrotreating catalyst is loaded in the low-temperature hydrogenation reaction zone, and a second hydrotreating catalyst is loaded in the high-temperature hydrogenation reaction zone; the first hydrotreating catalyst and the second hydrotreating catalyst are the same or different, preferably different.

[0012] Further, in the above method, the first hydrotreating catalyst and the second hydrotreating catalyst include a carrier and an active metal; the carrier includes a porous refractory inorganic oxide such as alumina, and according to actual needs, various other additives such as at least one of P, Si, F, and B can be selectively added; the active metal is generally a metal of Group VIB and / or Group VIII, preferably one or more of W, Mo, Co, and Ni; based on the total weight of the catalyst, the mass fraction of the active metal in terms of oxide is 5-35%. The first hydrotreating catalyst and the second hydrotreating catalyst can be commercial catalysts or can be prepared according to existing methods in the art; they can be oxidation-type catalysts and / or sulfur-loaded catalysts.

[0013] Further, in the above method, the most probable pore diameter of the first hydrotreating catalyst and the second hydrotreating catalyst is 5-15 nm, the B / L acid ratio is 0.1-0.5, and the total infrared acid amount is 0.2-0.45 mmol / g.

[0014] Further, in the above method, the specific surface area of the first hydrotreating catalyst and the second hydrotreating catalyst is 150-300 m 2 / g, preferably 160-280 m 2 / g; the pore volume is 0.2-0.6 mL / g, preferably 0.25-0.55 mL / g.

[0015] Further, in the above method, the most probable pore diameter of the second hydrotreating catalyst is 1-10 nm smaller than that of the first hydrotreating catalyst, preferably 2-8 nm.

[0016] Further, in the above method, the B / L acid ratio of the second hydrotreating catalyst is 0.05-0.2 smaller than that of the first hydrotreating catalyst, preferably 0.1-0.2.

[0017] Further, in the above method, the total infrared acidity of the second hydrotreating catalyst is 0.05 - 0.20 mmol / g higher than that of the first hydrotreating catalyst, preferably 0.05 - 0.15 mmol / g.

[0018] Further, in the above method, the active metal content of the second hydrotreating catalyst is 1 - 15 wt% lower than that of the first hydrotreating catalyst, preferably 2 - 12 wt%.

[0019] Further, in the above method, the volume ratio of the first hydrotreating catalyst loaded in the low-temperature hydrocracking reaction zone to the second hydrotreating catalyst loaded in the high-temperature hydrocracking reaction zone is (20 - 50):100, preferably (50 - 80):100.

[0020] Further, in the above method, at least one hydrocracking reactor is provided in both the low-temperature hydrocracking reaction zone and the high-temperature hydrocracking reaction zone; furthermore, the hydrocracking reactor can be a trickle-bed reactor, a fluidized-bed reactor, or a tubular reactor; it can be a single reactor type or a combination of one or more of them.

[0021] Further, in the above method, hydrocarbon-containing raw materials can be co-processed while treating the ethylene tar raw material. The hydrocarbon-containing raw materials and the ethylene tar raw material are mixed with hydrogen-containing gas and then sequentially pass through the low-temperature hydrocracking reaction zone and the high-temperature hydrocracking reaction zone, and finally a liquid product is obtained through separation; the hydrocarbon-containing raw materials can be selected from one or more of catalytic gasoline, catalytic diesel, catalytic wax oil, catalytic slurry oil, coker gasoline, coker diesel, and coker wax oil.

[0022] Further, in the above method, the hydrogen-containing gas is hydrogen or a mixture of hydrogen and other gases; the other gas can be the high-pressure gas and / or the low-pressure gas from the hydrocracking unit; furthermore, the high-pressure gas can be from a hydrocracking unit with a hydrogen partial pressure in the range of 4.0 - 20.0 MPa, including hydrocracking units for naphtha, diesel, wax oil, and residue oil, etc.

[0023] Further, in the above method, the operating conditions of the low-temperature hydrocracking reaction zone and the high-temperature hydrocracking reaction zone are generally as follows: reaction pressure 3 - 30 MPa, preferably 4 - 25 MPa; volume space velocity 0.1 - 10.0 h -1 , preferably 0.2 - 4.0 h -1 ; hydrogen-oil volume ratio 200 - 1000, preferably 250 - 800.

[0024] Further, in the above method, the finally obtained liquid product through separation can be used to preheat the raw material oil or be mixed with the raw material oil as recycle oil.

[0025] The second aspect of the present invention provides a hydrotreating system for ethylene tar, and the hydrotreating system includes: A low-temperature hydrotreating reaction zone, which is used to receive ethylene tar raw materials and hydrogen-containing gas, and perform hydrotreating under the action of a first hydrotreating catalyst; A high-temperature hydrotreating reaction zone, which is used to receive the reaction effluent from the low-temperature hydrotreating reaction zone and hydrogen-containing gas, and perform a reaction under the action of a second hydrotreating catalyst; A gas-liquid separation unit, which receives the reaction effluent from the high-temperature hydrotreating reaction zone, and obtains gas-phase and liquid-phase products after separation.

[0026] Furthermore, in the above hydrotreating system, a raw material heating furnace may not be provided, and only a hydrogen heating furnace and a startup furnace need to be provided. After the ethylene tar raw material is heat-exchanged with the liquid-phase product, it is mixed with the hydrogen-containing gas heated by the hydrogen heating furnace and then enters the low-temperature hydrotreating reaction zone.

[0027] Furthermore, in the above hydrotreating system, at least one hydrotreating reactor is provided in both the low-temperature hydrotreating reaction zone and the high-temperature hydrotreating reaction zone; furthermore, the hydrotreating reactor may be a trickle-bed reactor, a fluidized-bed reactor, or a tubular reactor, and may be a single reactor type, or a combination of one or several of them.

[0028] Furthermore, in the above hydrotreating system, the gas-liquid separation unit can be set by using the existing technologies in the art. Specifically in the present invention, the gas-liquid separation unit generally includes a hot high-pressure separator, a hot low-pressure separator, a cold high-pressure separator, and a cold low-pressure separator.

[0029] Compared with the prior art, the beneficial effects of the ethylene tar hydrotreating method and the treating system provided by the present invention are as follows: 1. The present invention first proposes a method for fractionally removing olefins in ethylene tar, which greatly improves the operation stability of the ethylene tar processing device. Based on the research on the molecular structure and reaction characteristics of ethylene tar, a low-temperature hydrotreating reaction zone and a high-temperature hydrotreating reaction zone are sequentially arranged along the liquid-phase material flow direction, aiming to remove type I olefins and type II olefins in different zones. Different olefins in ethylene tar can be removed separately under different reaction conditions, which can ensure the removal effect of olefins while effectively avoiding the occurrence of olefin coking reactions, and greatly improve the operation stability of the ethylene tar hydrotreating and subsequent processing devices.

[0030] 2. In the ethylene tar hydrotreating method provided by the present invention, hydrotreating catalysts with different properties are loaded in a graded manner in the low-temperature hydrotreating reaction zone and the high-temperature hydrotreating reaction zone. Ethylene tar contacts the hydrotreating catalysts loaded in the low-temperature hydrotreating reaction zone and the high-temperature hydrotreating reaction zone in sequence along the material flow direction. The first hydrotreating catalyst loaded in the low-temperature hydrotreating reaction zone has a low total infrared acid amount and a high B acid / L acid ratio, which can avoid the formation of too strong adsorption between type I olefins in ethylene tar and L acid sites (type I olefins in ethylene tar are more likely to be adsorbed on the L acid sites on the catalyst surface), and prevent reactions such as condensation and coking. The second hydrotreating catalyst loaded in the high-temperature hydrotreating reaction zone has a high total infrared acid amount and a low B acid / L acid ratio, which can inhibit the occurrence of isomerization reactions and reduce steric hindrance effects, thereby improving the removal efficiency of type II olefins.

[0031] 3. In the ethylene tar hydrotreating method provided by the present invention, type I olefins contained in ethylene tar have a large electron cloud density, and molecules are prone to aggregation due to non-bonding interactions. Therefore, compared with the second hydrotreating catalyst loaded in the high-temperature hydrotreating reaction zone, the first hydrotreating catalyst loaded in the low-temperature hydrotreating reaction zone has a larger probable pore size, which helps to reduce diffusion limitations during the reaction.

[0032] 4. In the ethylene tar hydrotreating method provided by the present invention, the active metal content of the first hydrotreating catalyst loaded in the low-temperature hydrotreating reaction zone is higher than that of the second hydrotreating catalyst in the high-temperature hydrotreating reaction zone. The higher activity of the catalyst in the low-temperature hydrotreating reaction zone can increase the removal efficiency of type I olefins; while the lower activity of the catalyst in the high-temperature hydrotreating reaction zone can reduce the intensity of the reaction and improve the operation stability of the device.

[0033] 5. The present invention effectively reduces energy consumption by setting a reasonable heat exchange scheme. The liquid-phase product is used to preheat the feedstock oil, which can fully utilize the heat generated by the olefin hydrogenation saturation reaction in ethylene tar, eliminating the feedstock heating furnace. The heat supply for the reaction system is provided by the reaction heat, greatly reducing heat consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a process flow schematic diagram of the ethylene tar hydrotreating method of the present invention.

[0035] Among them, 1 - feedstock oil; 2 - hydrogen-containing gas; 3 - low-temperature hydrotreating reaction zone; 4 - first reaction material; 5 - high-temperature hydrotreating reaction zone; 6 - second reaction material; 7 - gas-liquid separation zone; 8 - gas-phase product; 9 - liquid-phase product.

[0036] Figure 2 is a process flow schematic diagram of the ethylene tar hydrotreating method used in Comparative Example 1 of the present invention.

[0037] Among them, 1 - feedstock oil; 2 - hydrogen-containing gas; 3 - hydrogenation reaction zone; 4 - first reaction material; 5 - gas-liquid separation zone; 6 - gas-phase product; 7 - liquid-phase product. Embodiment

[0038] The technical solutions and effects of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but are not limited to the following embodiments.

[0039] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the protection scope of the present invention is not limited by these specific embodiments, but is determined by the appended claims.

[0040] All publications, patent applications, patents, and other references mentioned in this specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0041] When this specification uses prefixes such as "well-known to those skilled in the art", "prior art", or similar terms to introduce materials, substances, methods, steps, devices, or components, etc., the objects introduced by such prefixes cover those commonly used in the art at the time when this application is filed, but also include those that are not commonly used at present but will become commonly recognized in the art as suitable for similar purposes.

[0042] Unless otherwise clearly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprising of", etc. will be understood to include the stated elements or components, without excluding other elements or other components.

[0043] In this article, all numerical values of parameters (e.g., quantities or conditions) should be understood to be modified by the term "about" in all cases, whether or not "about" actually appears before the numerical value.

[0044] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, and the pressure is gauge pressure.

[0045] In the context of this specification, any two or more embodiments of the present invention can be arbitrarily combined, and the technical solutions formed thereby belong to a part of the original public content of this specification and also fall within the protection scope of the present invention.

[0046] Such as Figure 1As shown, the feedstock oil 1 and the hydrogen-containing gas 2 are mixed and then enter the low-temperature hydrogenation reaction zone 3. After the obtained first reaction material 4 is mixed with the hydrogen-containing gas 2, it enters the high-temperature hydrogenation reaction zone 5. The obtained second reaction material 6 enters the gas-liquid separation zone 7, and a gas-phase product 8 and a liquid-phase product 9 are separated out.

[0047] As Figure 2 shown, the feedstock oil 1 and the hydrogen-containing gas 2 are mixed and then enter the low-temperature hydrogenation reaction zone 3. The obtained first reaction material 4 enters the gas-liquid separation zone 5, and a gas-phase product 8 and a liquid-phase product 9 are separated out.

[0048] Examples 1-5 One fixed-bed hydrogenation reactor is provided in each of the low-temperature hydrogenation reaction zone and the high-temperature hydrogenation reaction zone, which are respectively filled with a first hydrotreating catalyst and a second hydrotreating catalyst. Both the first hydrotreating catalyst and the second hydrotreating catalyst use alumina as the carrier, and the active metal components include molybdenum and nickel. The specific properties of the catalyst are shown in Table 1. The properties of the ethylene tar feedstock oil used are shown in Table 2. The catalyst loading schemes and process conditions of Examples 1 to 5 are shown in Tables 3 to 7 respectively, and the test results are shown in Tables 8 to 9 respectively.

[0049] Table 1 Physical and Chemical Properties of Catalyst A and Catalyst B

[0050] Table 2 Properties of Ethylene Tar Feedstock

[0051] Table 3 Catalyst Loading Scheme and Process Conditions of Example 1

[0052] Table 4 Catalyst Loading Scheme and Process Conditions of Example 2

[0053] Table 5 Catalyst Loading Scheme and Process Conditions of Example 3

[0054] Table 6 Catalyst Loading Scheme and Process Conditions of Example 4

[0055] Table 7 Catalyst Loading Scheme and Process Conditions of Example 5

[0056] Table 8 Test Results of Examples 1, 3 and 4

[0057] Table 9 Test Results of Examples 2 and 5

[0058] As can be seen from Table 8 and Table 9, the liquid-phase products in Examples 1, 3, and 4 can be used as blending components for low-sulfur marine fuels, and the liquid-phase products in Examples 2 and 5 can be used as raw materials for producing low-sulfur petroleum coke.

[0059] Comparative Example 1 In Comparative Example 1, no low-temperature hydrogenation reaction zone is set up, and the feedstock oil directly enters the high-temperature reaction zone. The high-temperature reaction zone is equipped with 1 fixed-bed hydrogenation reactor, and the hydrotreating catalyst loaded is the first hydrotreating catalyst A. The process conditions are as follows: reaction pressure 9.0 MPa, reaction temperature 260 °C, hydrogen-oil volume ratio 360, and volume space velocity 1.0 h -1 . The test results of Comparative Example 1 are shown in Table 10.

[0060] Table 10 Implementation effects of the comparative example

[0061] The pressure drop conditions of the devices in Examples 1-5 and Comparative Example 1 are shown in Table 11.

[0062] Table 11 Pressure drops of the devices in Examples 1-5 and Comparative Example 1

Claims

1. A method for hydrotreating ethylene tar, characterized in that: The treatment method includes the following: The ethylene tar raw material and the hydrogen-containing gas are mixed and then successively passed through a low-temperature hydrotreating reaction zone and a high-temperature hydrotreating reaction zone, and finally a liquid product is obtained through separation; the reaction temperature of the low-temperature hydrotreating reaction zone is 80-175 °C, preferably 100-175 °C; the reaction temperature of the high-temperature hydrotreating reaction zone is 180-380 °C, preferably 180-360 °C.

2. The method according to claim 1, characterized in that: By controlling the temperature difference between the low-temperature hydrotreating reaction zone and the high-temperature hydrotreating reaction zone, the olefin content of the final liquid product is regulated, and thus the use of the liquid product is regulated.

3. The method according to claim 2, characterized in that: The temperature difference between the reaction temperatures of the low-temperature hydrotreating reaction zone and the high-temperature hydrotreating reaction zone is 5-85 °C, preferably 10-80 °C, and the olefin content of the final liquid product is regulated to be 3.0-9.0 mol%, preferably 4.0-8.0 mol%.

4. The method according to claim 2, characterized in that: The temperature difference between the reaction temperatures of the low-temperature hydrotreating reaction zone and the high-temperature hydrotreating reaction zone is 85-250 °C, preferably 85-220 °C, and the olefin content of the final liquid product is regulated to be 0-2.0 mol%, preferably 0-1.0 mol%.

5. The method according to claim 1, characterized in that: A first hydrotreating catalyst is loaded in the low-temperature hydrotreating reaction zone, and a second hydrotreating catalyst is loaded in the high-temperature hydrotreating reaction zone; the first hydrotreating catalyst and the second hydrotreating catalyst are the same or different, preferably different.

6. The method according to claim 5, characterized in that: The most probable pore diameter of the first hydrotreating catalyst and the second hydrotreating catalyst is 5-15 nm, the B / L acid ratio is 0.1-0.5, and the total infrared acid amount is 0.2-0.45 mmol / g.

7. The method according to claim 5, characterized in that: The specific surface area of the first hydrotreating catalyst and the second hydrotreating catalyst is 150 to 300 m 2 / g, preferably 160 to 280 m 2 / g; the pore volume is 0.2 to 0.6 mL / g, preferably 0.25 to 0.55 mL / g.

8. The method according to claim 5, characterized in that: The most probable pore diameter of the second hydrotreating catalyst is 1-10 nm smaller than that of the first hydrotreating catalyst, preferably 2-8 nm.

9. The method according to claim 5, characterized in that: The B / L acid ratio of the second hydrotreating catalyst is 0.05-0.2 smaller than that of the first hydrotreating catalyst, preferably 0.1-0.

2.

10. The method according to claim 5, characterized in that: The total infrared acid amount of the second hydrotreating catalyst is 0.05-0.20 mmol / g higher than that of the first hydrotreating catalyst, preferably 0.05-0.15 mmol / g.

11. The method according to claim 5, characterized in that: The active metal content of the second hydrotreating catalyst is 1-15 wt% lower than that of the first hydrotreating catalyst, preferably 2-12 wt%.

12. The method according to claim 5, characterized in that: The volume ratio of the first hydrotreating catalyst loaded in the low-temperature hydrogenation reaction zone to the second hydrotreating catalyst loaded in the high-temperature hydrogenation reaction zone is (20 - 50):100, preferably (50 - 80):

100.

13. According to the method described in claim 1, it is characterized in that: When treating the ethylene tar raw material, a hydrocarbon-containing raw material is also co-processed. The hydrocarbon-containing raw material and the ethylene tar raw material are mixed with a hydrogen-containing gas and then sequentially pass through the low-temperature hydrogenation reaction zone and the high-temperature hydrogenation reaction zone, and finally a liquid-phase product is obtained after separation; the hydrocarbon-containing raw material is selected from one or more of catalytic gasoline, catalytic diesel, catalytic wax oil, catalytic slurry, coker gasoline, coker diesel, and coker wax oil.

14. According to the method described in claim 1, it is characterized in that: The hydrogen-containing gas is hydrogen or a mixture of hydrogen and other gases; the other gas is the high-pressure gas and / or low-pressure gas from the hydrogenation unit.

15. According to the method described in claim 1, it is characterized in that: The operating conditions of the low-temperature hydrogenation reaction zone and the high-temperature hydrogenation reaction zone are as follows: the reaction pressure is 3 to 30 MPa, preferably 4 to 25 MPa; the space velocity is 0.1 to 10.0 h -1 , preferably 0.2 to 4.0 h -1 ; the hydrogen-oil volume ratio is 200 to 1000, preferably 250 to 800.

16. A hydrotreating system for ethylene tar, it is characterized in that: The hydrotreating system includes: A low-temperature hydrogenation reaction zone, which is used to receive the ethylene tar raw material and the hydrogen-containing gas and perform hydrotreating under the action of the first hydrotreating catalyst; A high-temperature hydrogenation reaction zone, which is used to receive the reaction effluent from the low-temperature hydrogenation reaction zone and the hydrogen-containing gas and perform a reaction under the action of the second hydrotreating catalyst; A gas-liquid separation unit, which receives the reaction effluent from the high-temperature hydrogenation reaction zone and separates to obtain a gas-phase product and a liquid-phase product.

17. According to the processing system described in claim 16, it is characterized in that: At least one hydrogenation reactor is provided in both the low-temperature hydrogenation reaction zone and the high-temperature hydrogenation reaction zone; the hydrogenation reactor is one or more of a trickle-bed reactor, a fluidized-bed reactor, and a tubular reactor.

18. According to the processing system described in claim 16, it is characterized in that: The gas-liquid separation unit includes a hot high-pressure separator, a hot low-pressure separator, a cold high-pressure separator, and a cold low-pressure separator.

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