A method and system for producing needle coke raw material from catalytic slurry oil and a method and system for producing needle coke

Abstract

This invention discloses a method and system for producing needle coke feedstock from catalytic slurry oil, as well as a method and system for producing needle coke. The method involves first purifying the catalytic slurry oil, then performing a hydrogenation reaction. The resulting liquid product is fractionated to obtain light oil, middle distillate oil, and tail oil. The middle distillate oil enters a cracking unit for cracking. The resulting cracking products are mixed with the tail oil and sent to the coking unit as the first feedstock for needle coke production. Coking oil and gas are separated to obtain heavy coking oil, which is returned to the coking unit as the second feedstock for needle coke production. The system includes a purification unit, a hydrogenation reaction unit, a gas-liquid separation unit, a fractionation unit, a cracking reaction unit, and a coking unit. This invention proposes an optimization direction for needle coke feedstock, yielding high-quality needle coke feedstock and needle coke product.

Description

Technical Field

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

[0002] Catalytic oil slurry is rich in aromatics and is a high-quality raw material for needle coke production. However, it contains high levels of ash and sulfur, generally requiring desolidification and desulfurization treatment before it can be used as a raw material for needle coke production. Currently, the desolidification of catalytic oil slurry generally requires reducing the ash content to below 0.01 wt%, and the main methods include filtration, flocculation sedimentation, centrifugation-electrostatic separation, electroadsorption separation, centrifugation, and vacuum distillation. Desulfurization mainly uses hydrogenation to reduce the sulfur content in the catalytic oil slurry to below 0.5 wt%.

[0003] CN1872963A discloses a pretreatment method for feedstock in needle coke production. The feedstock oil is first subjected to vacuum distillation to remove non-ideal components. The remaining ideal components are then contacted with hydrogen and a hydrogenation catalyst. The hydrogenation reaction stream is separated to obtain the feedstock for needle coke production. This method, through a combination of two processes, can remove both light and heavy non-ideal components from the feedstock oil, utilize hydrogen more efficiently, save investment, and retain ideal components to the maximum extent. The treated feedstock oil meets the requirements for needle coke production. CN103789028A discloses a pretreatment method for needle coke feedstock production using catalytic slurry oil, including the following: the catalytic slurry oil is filtered and then subjected to mild hydrogenation treatment. 20%–50% (by weight) of the hydrogenated oil is sent to a vacuum distillation unit under operating conditions of 5 mmHg–100 mmHg pressure and 300–450°C temperature. The resulting hydrogenated light distillate oil is mixed with the remaining hydrogenated oil as feedstock for needle coke production. This method is suitable for producing needle coke feedstock using aromatic-rich catalytic slurry oil. CN103013567A discloses a method for producing needle coke feedstock from catalytic cracking slurry. This invention establishes a protected zone and a hydrotreating reaction zone. The catalytic cracking slurry first enters the protected zone, where most of the catalytic cracking catalyst powder is adsorbed. Then, it is mixed with hydrogen and fed into a heating furnace. After heating, it enters the hydrotreating reaction zone for hydrotreating. By setting up a protected zone before the hydrotreating reaction zone, this invention can filter out most of the catalytic cracking catalyst powder entrained in the catalytic cracking slurry, thus protecting the main hydrotreating catalyst and enabling long-term operation. Furthermore, through hydrorefining of the catalytic cracking slurry, most of the sulfur in the catalytic cracking slurry is removed, producing qualified needle coke feedstock.

[0004] In summary, current pretreatment methods for needle coke feedstock generally involve first removing catalyst powder through filtration, adsorption, and vacuum distillation, and then using hydrogenation to remove some sulfur. The resulting refined oil slurry has sufficient ash and sulfur content to meet the requirements for needle coke production and can be directly used as a raw material for needle coke production. Summary of the Invention

[0005] During the research process, the applicant discovered that during the hydrotreating of catalytic slurry, while desulfurization is achieved, some aromatic rings of the aromatics are also saturated through hydrogenation and further converted into aromatics with a large number of alkyl and / or cycloalkyl side chains. These side-chain-containing aromatics undergo a side-chain breaking reaction first during the subsequent needle coke production process, generating a large number of small-molecule hydrocarbons. On the one hand, the newly generated small-molecule hydrocarbons continuously escape, causing disturbance to the reaction system and hindering the formation of a broad-area mesophase; on the other hand, some small-molecule hydrocarbons, such as monocyclic and / or bicyclic aromatics, cannot escape the reaction system and inevitably undergo condensation reactions while remaining in the system. During the reaction cycle, these small molecules do not have enough time to form sufficiently large molecules and solidify into coke before forming a broad-area mesophase. The performance of this coke differs significantly from that of needle coke, affecting the overall performance of the needle coke product. Especially in the later stage of needle coke preparation, during the coke pulling and solidification stage, a large number of small molecule hydrocarbons escape rapidly, resulting in a large number of gaps in the solidified system. The porosity of the needle coke is high, which in turn leads to low tap density and particle strength of the needle coke, making it impossible to obtain high-quality needle coke.

[0006] To address the shortcomings of existing technologies, the main objective of this invention is to provide a method and system for producing needle coke feedstock from catalytic oil slurry, as well as a method and system for producing needle coke. This invention, from a molecular refining perspective, through in-depth analysis of the molecular reactivity of feedstocks and correlation analysis between feedstock composition and needle coke properties, proposes optimization directions for needle coke feedstocks, resulting in high-quality needle coke feedstocks and needle coke products. This solves the problem in existing technologies where the needle coke tap density and particle strength are low due to desolidification and desulfurization treatments in catalytic oil slurry.

[0007] To achieve the above-mentioned objective, the first aspect of the present invention provides a method for producing needle coke feedstock from catalytic slurry oil, the method comprising the following:

[0008] (1) After purification, the catalytic oil slurry enters the hydrogenation reaction unit together with hydrogen. Under the action of the hydrogenation catalyst, a hydrogenation reaction occurs. The reaction effluent is separated to obtain gaseous products and liquid products.

[0009] (2) The liquid product obtained in step (1) is fractionated by the first fractionation unit to obtain light oil, middle distillate oil and tail oil;

[0010] (3) The middle distillate oil obtained in step (2) is sent to the cracking reaction unit for cracking reaction. The cracking products obtained are mixed with the tail oil obtained in step (2) and used as the first raw material for the production of needle coke.

[0011] Furthermore, in the above-mentioned method for producing needle coke feedstock by catalytic oil slurry, the ash content of the catalytic oil slurry in step (1) is generally higher than 0.01wt%, the sulfur content is generally higher than 0.4wt%, or even higher than 0.8wt%, and the aromatic carbon content is not less than 60mol%, preferably 65mol% to 90mol%.

[0012] Furthermore, in the above-mentioned method for producing needle coke feedstock using catalytic slurry, the purification treatment in step (1) can be one or more of the following methods: filtration, centrifugal sedimentation, flocculation sedimentation, and vacuum distillation. Filtration is preferred. The filtration equipment can be one or a combination of sintered metal powder filter, metal wire mesh filter, and ceramic membrane filter, preferably a ceramic membrane filter. The catalytic slurry filtration temperature is 120℃~280℃, preferably 170℃~230℃. The catalytic slurry can be mixed with a diluent for filtration. The diluent can be an oil with good miscibility with the catalytic slurry, such as at least one of diesel oil, furfural, and aromatic solvent oil, preferably diesel oil. Generally, the mass ratio of catalytic slurry to diluent is 100:1~100:20, preferably 100:5~100:12. After purification, the ash content of the catalytic slurry is not greater than 0.01wt%, preferably not greater than 0.005wt%.

[0013] Furthermore, in the above method for producing needle coke feedstock from catalytic slurry oil, the hydrogenation reaction unit in step (1) is equipped with at least one hydrogenation reactor. When two or more hydrogenation reactors are set, there are no particular restrictions on the connection method between the reactors, and they are generally connected in series. 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.

[0014] Furthermore, in the above-mentioned method for producing needle coke feedstock from catalytic slurry oil, the hydrogenation catalyst in step (1) generally uses alumina as a support, and the active component is an oxide of Group VIB and / or Group VIII metals, such as one or a combination of oxides of metals like Mo, W, Co, and Ni. The hydrogenation catalyst can be prepared using methods existing in the art, or using existing commercial catalysts, such as the FZC series hydrogenation catalysts developed by the Dalian Petrochemical Research Institute of Sinopec.

[0015] Furthermore, in the above method for producing needle coke feedstock using catalytic slurry oil, the hydrogenation reaction conditions in step (1) are as follows: reaction temperature is 300℃~480℃, preferably 330℃~390℃; reaction pressure is 2MPa~20MPa, preferably 4MPa~8MPa; hydrogen-to-oil volume ratio is 100~2500, preferably 500~1800; and liquid hourly space velocity is 0.1h. -1 ~2.0h -1 Preferably 0.7h -1 ~1.2h -1 .

[0016] Furthermore, in the above-mentioned method for producing needle coke feedstock by catalytic oil slurry, the separation in step (1) is a gas-liquid two-phase separation. Generally, the separation system includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, and a cold low-pressure separator.

[0017] Furthermore, in the above-mentioned method for producing needle coke feedstock from catalytic slurry, the hydrogenated liquid product mentioned in step (1) generally refers to the liquid fraction after removing the naphtha fraction.

[0018] Furthermore, in the above-mentioned method for producing needle coke feedstock by catalytic slurry, the sulfur content of the hydrogenation liquid product in step (1) is not greater than 0.5 wt%, preferably not greater than 0.4 wt%.

[0019] Furthermore, in the above method for producing needle coke feedstock using catalytic slurry oil, the light oil obtained in step (2) can be directly discharged from the unit as a product, or enter the condensation reaction unit for reaction, or part of it can be discharged from the unit as a product and the remainder can enter the condensation reaction unit for reaction. Furthermore, the condensation reaction unit can be at least one of tubular reactor, tower reactor, and tank reactor, preferably tower reactor. The condensation reaction conditions are: reaction temperature of 350℃~550℃, preferably 400℃~460℃, reaction pressure of 0.1MPa~5MPa, preferably 0.8MPa~3.0MPa, and residence time of 0.01h~50h, preferably 0.3h~24h. After separation, the reaction products obtained from the condensation reaction yield top oil and bottom oil. Generally, the bottom oil 5% distillation temperature is controlled at 300℃~420℃, preferably 330℃~370℃. The top oil can be directly discharged from the device, or it can be used as a diluent to be mixed with the catalytic oil slurry in step (1) for purification; the bottom oil is recycled back to be processed together with the liquid product obtained in step (1).

[0020] Furthermore, in the above-mentioned method for producing needle coke feedstock using catalytic slurry oil, a condensation catalyst is preferably added during the condensation reaction. The condensation reaction is carried out under the action of the condensation catalyst, which includes a support and an active component. The support is one or a combination of several selected from kaolin, montmorillonite, alumina, and silica-containing alumina, preferably alumina. The active component is at least one oxide of a Group IVB and / or Group VIB metal, such as zirconium, tungsten, molybdenum, etc. Based on the weight of the catalyst, the content of the active component is 0.1 wt% to 50 wt%, preferably 5 wt% to 25 wt%. The condensation catalyst can be spherical, cylindrical, cloverleaf, four-leaf, Raschig ring, etc., or a combination of several of these shapes.

[0021] Furthermore, in the above-mentioned method for producing needle coke feedstock by catalytic oil slurry, the 5% distillation temperature of the middle distillate oil in step (2) is 340℃~430℃, preferably 355℃~410℃, and the 95% distillation temperature is 440℃~530℃, preferably 460℃~505℃.

[0022] Furthermore, in the above method for producing needle coke feedstock from catalytic slurry oil, the cracking reaction unit in step (3) is equipped with at least one reactor. The reactor can be one or a combination of tubular reactor, tower reactor, and tank reactor, preferably a tower reactor. The reaction conditions of the cracking reaction unit are: reaction temperature of 380℃~520℃, preferably 420℃~490℃, reaction pressure of 0.1MPa~5MPa, preferably 0.2MPa~1.0MPa, and residence time of 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 gas (such as helium, neon, argon, etc.), preferably water vapor; the mass ratio of middle distillate oil to carrier gas is 100:0.1~100:20, preferably 100:1~100:8.

[0023] Furthermore, in the above method for producing needle coke feedstock using catalytic slurry, the mass ratio of cracking products to tail oil in step (3) is 1:9 to 9:1, preferably 4:6 to 8:2.

[0024] Furthermore, in the above-mentioned method for producing needle coke feedstock by catalytic slurry, the aromatic carbon content of the first feedstock in step (3) is 60 mol% to 90 mol%, preferably 65 mol% to 85 mol%.

[0025] A second aspect of the present invention provides a method for producing needle coke from catalytic slurry oil, the method comprising the following steps:

[0026] (1) After purification, the catalytic oil slurry enters the hydrogenation reaction unit together with hydrogen. Under the action of the hydrogenation catalyst, a hydrogenation reaction occurs. The reaction effluent is separated to obtain gaseous products and liquid products.

[0027] (2) The liquid product obtained in step (1) is fractionated by the first fractionation unit to obtain light oil, middle distillate oil and tail oil;

[0028] (3) The middle distillate oil obtained in step (2) is sent to the cracking reaction unit for cracking reaction. The cracking products obtained are mixed with the tail oil obtained in step (2) and used as the first raw material for the production of needle coke.

[0029] (4) The first raw material obtained in step (3) is sent to the coking unit. The coking oil and gas obtained from the reaction are separated by the second fractionation unit to obtain coking gas, coking light oil and coking heavy oil. The coking heavy oil is returned to the coking unit as the second raw material for producing needle coke.

[0030] Furthermore, in the above-mentioned method for producing needle coke from catalytic oil slurry, the ash content of the catalytic oil slurry in step (1) is generally higher than 0.01wt%, the sulfur content is generally higher than 0.4wt%, or even higher than 0.8wt%, and the aromatic carbon content is not less than 60mol%, preferably 65mol% to 90mol%.

[0031] Furthermore, in the above-mentioned method for producing needle coke from catalytic slurry, the purification treatment in step (1) can be one or more of the following methods: filtration, centrifugal sedimentation, flocculation sedimentation, and vacuum distillation. Filtration is preferred. The filtration equipment can be one or a combination of sintered metal powder filter, metal wire mesh filter, and ceramic membrane filter, preferably a ceramic membrane filter. The catalytic slurry filtration temperature is 120℃~280℃, preferably 170℃~230℃. The catalytic slurry can be mixed with a diluent for filtration. The diluent can be an oil with good miscibility with the catalytic slurry, such as at least one of diesel oil, furfural, and aromatic solvent oil, preferably diesel oil. Generally, the mass ratio of catalytic slurry to diluent is 100:1~100:20, preferably 100:5~100:12. After purification, the ash content of the catalytic slurry is not greater than 0.01wt%, preferably not greater than 0.005wt%.

[0032] Furthermore, in the above-mentioned method for producing needle coke from catalytic slurry, the hydrogenation reaction unit in step (1) is equipped with at least one hydrogenation reactor. When two or more hydrogenation reactors are set, there are no particular restrictions on the connection method between the reactors, and they are generally connected in series. The hydrogenation reactor can be selected from one or more combinations of fluidized bed reactors, suspended bed reactors, fixed bed reactors, etc., and is preferably a fixed bed reactor.

[0033] Furthermore, in the above-mentioned method for producing needle coke from catalytic slurry oil, the hydrogenation catalyst in step (1) generally uses alumina as a support, and the active component is an oxide of Group VIB and / or Group VIII metals, such as one or a combination of oxides of metals like Mo, W, Co, and Ni. The hydrogenation catalyst can be prepared using methods existing in the art, or using existing commercial catalysts, such as the FZC series hydrogenation catalysts developed by the Dalian Petrochemical Research Institute of Sinopec.

[0034] Furthermore, in the above method for producing needle coke from catalytic slurry oil, the hydrogenation reaction conditions in step (1) are as follows: reaction temperature is 300℃~480℃, preferably 330℃~390℃; reaction pressure is 2MPa~20MPa, preferably 4MPa~8MPa; hydrogen-to-oil volume ratio is 100~2500, preferably 500~1800; and liquid hourly space velocity is 0.1h. -1 ~2.0h -1 Preferably 0.7h -1 ~1.2h -1 .

[0035] Furthermore, in the above-mentioned method for producing needle coke from catalytic oil slurry, the separation in step (1) is a gas-liquid two-phase separation. Generally, the separation system includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, and a cold low-pressure separator.

[0036] Furthermore, in the above-mentioned method for producing needle coke from catalytic oil slurry, the hydrogenated liquid product mentioned in step (1) generally refers to the liquid fraction after removing the naphtha fraction.

[0037] Furthermore, in the above-mentioned method for producing needle coke feedstock by catalytic slurry, the sulfur content of the hydrogenation liquid product in step (1) is not greater than 0.5 wt%, preferably not greater than 0.4 wt%.

[0038] Furthermore, in the above-mentioned method for producing needle coke from catalytic slurry oil, the light oil obtained in step (2) can be directly discharged from the unit as a product, or enter the condensation reaction unit for reaction, or part of it can be discharged from the unit as a product and the remainder can enter the condensation reaction unit for reaction. Furthermore, the condensation reaction unit can be at least one of tubular reactor, tower reactor, and tank reactor, preferably tower reactor. The condensation reaction conditions are: reaction temperature of 350℃~550℃, preferably 400℃~460℃, reaction pressure of 0.1MPa~5MPa, preferably 0.8MPa~3.0MPa, and residence time of 0.01h~50h, preferably 0.3h~24h. After separation, the reaction products obtained from the condensation reaction yield top oil and bottom oil. Generally, the bottom oil 5% distillation temperature is controlled at 300℃~420℃, preferably 330℃~370℃. The top oil can be directly discharged from the device, or it can be used as a diluent to be mixed with the catalytic oil slurry in step (1) for purification; the bottom oil is recycled back to be processed together with the liquid product obtained in step (1).

[0039] Furthermore, in the above-mentioned method for producing needle coke from catalytic slurry oil, a condensation catalyst is preferably added during the condensation reaction. The condensation reaction is carried out under the action of the condensation catalyst, which includes a support and an active component. The support is one or a combination of several selected from kaolin, montmorillonite, alumina, and silica-containing alumina, preferably alumina. The active component is at least one oxide of a Group IVB and / or Group VIB metal, such as zirconium, tungsten, molybdenum, etc. Based on the weight of the catalyst, the content of the active component is 0.1wt% to 50wt%, preferably 5wt% to 25wt%. The condensation catalyst can be spherical, cylindrical, cloverleaf, four-leaf, Raschig ring, etc., or a combination of several of these shapes.

[0040] Furthermore, in the above-mentioned method for producing needle coke from catalytic oil slurry, the 5% distillation temperature of the middle distillate oil in step (2) is 340℃~430℃, preferably 355℃~410℃, and the 95% distillation temperature is 440℃~530℃, preferably 460℃~505℃.

[0041] Furthermore, in the above-mentioned method for producing needle coke from catalytic oil slurry, the cracking reaction unit in step (3) is equipped with at least one reactor. The reactor can be one or a combination of tubular reactor, tower reactor, and tank reactor, preferably a tower reactor. The reaction conditions of the cracking reaction unit are: reaction temperature of 380℃~520℃, preferably 420℃~490℃, reaction pressure of 0.1MPa~5MPa, preferably 0.2MPa~1.0MPa, and residence time of 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 gas (such as helium, neon, argon, etc.), preferably water vapor; the mass ratio of middle distillate oil to carrier gas is 100:0.1~100:20, preferably 100:1~100:8.

[0042] Furthermore, in the above-mentioned method for producing needle coke from catalytic slurry, the mass ratio of cracking products to tail oil in step (3) is 1:9 to 9:1, preferably 4:6 to 8:2.

[0043] Furthermore, in the above-mentioned method for producing needle coke from catalytic oil slurry, the aromatic carbon content of the first raw material in step (3) is 60 mol% to 90 mol%, preferably 65 mol% to 85 mol%.

[0044] Furthermore, in the above-mentioned method for producing needle coke from catalytic slurry, the coking unit in step (4) 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. Generally, the outlet temperature of the heating furnace is 410℃~550℃, preferably 440℃~520℃, and more specifically, 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~96h, preferably 32h~54h.

[0045] Furthermore, in the above method for producing needle coke from catalytic oil slurry, the 5% distillation temperature of the coking heavy oil in step (4) is 280℃~380℃, preferably 310℃~360℃.

[0046] Furthermore, in the above method for producing needle coke from catalytic slurry oil, the coking reaction in step (4) is divided into two stages: the first raw material is introduced in the first stage, and the second raw material is introduced in the second stage. In each reaction stage, from the beginning to the end of the reaction stage, the raw material oil corresponding to that reaction stage is continuously added, and the raw material oil corresponding to a different reaction stage is not added.

[0047] Furthermore, in the above-mentioned method for producing needle coke from catalytic slurry, the reaction time of the first stage of coking reaction in step (4) is the first 20% to 80% of the reaction cycle, preferably 35% to 70%, and the reaction time of the second stage is the last 20% to 80% of the reaction cycle, preferably 40% to 60%. The end time of the first stage is the start time of the second stage.

[0048] A third aspect of the present invention provides a system for producing needle coke feedstock from catalytic slurry oil, comprising:

[0049] The purification unit is used to receive and process the catalytic oil slurry, and the purified oil slurry is obtained after processing.

[0050] The hydrogenation reaction unit is used to receive hydrogen and purified oil slurry obtained from the purification unit, and a hydrogenation reaction is carried out under the action of a hydrogenation catalyst.

[0051] The gas-liquid separation unit is used to receive the reaction effluent from the hydrogenation reaction unit and separate it to obtain gaseous and liquid products.

[0052] The first fractionation unit is used to receive the liquid product from the gas-liquid separation unit and fractionate it to obtain light oil, middle distillate oil and tail oil.

[0053] The cracking reaction unit is used to receive the middle distillate oil from the first fractionation unit, and after the reaction, the cracking products are mixed with the tail oil from the first fractionation unit as the first feedstock.

[0054] Furthermore, in the above-mentioned system for producing needle coke feedstock from catalytic slurry, the purification unit can adopt one or a combination of several methods such as filtration, centrifugal sedimentation, flocculation sedimentation, and vacuum distillation, with filtration being preferred. The further filtration equipment can be one or a combination of several methods such as sintered metal powder filter cartridges, metal wire mesh filter cartridges, and ceramic membrane filter cartridges, with ceramic membrane filter cartridges being preferred.

[0055] Furthermore, in the aforementioned system for producing needle coke feedstock from catalytic slurry oil, the hydrogenation reaction unit includes at least one hydrogenation reactor. When two or more hydrogenation reactors are used, there are no particular restrictions on the connection method between the reactors; they are generally connected in series. 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.

[0056] Furthermore, in the above-mentioned system for producing needle coke feedstock using catalytic oil slurry, the gas-liquid separation unit can be any of the devices capable of achieving gas-liquid two-phase separation. Generally, the gas-liquid separation unit includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, and a cold low-pressure separator.

[0057] Furthermore, in the above-mentioned system for producing needle coke feedstock from catalytic slurry, the first fractionation unit includes at least one fractionation tower, which can be either a packed tower or a plate tower.

[0058] Furthermore, in the aforementioned system for producing needle coke feedstock from catalytic slurry oil, the cracking reaction unit is equipped with at least one reactor. The reactor can be one or a combination of tubular reactors, tower reactors, and tank reactors, with a tower reactor being preferred.

[0059] Furthermore, the aforementioned system for producing needle coke feedstock from catalytic oil slurry includes a condensation reaction unit, which receives light oil from the first fractionation unit. The reaction products obtained from the condensation reaction are separated to obtain top oil and bottom oil. The bottom oil's 5% distillation temperature is generally controlled at 300℃–420℃, preferably 330℃–370℃. The top oil can be discharged directly from the unit or returned as a diluent to the purification unit for mixing with the catalytic oil slurry for purification. The bottom oil is recycled back to the first fractionation unit and processed together with the liquid product obtained from the gas-liquid separation unit. The condensation reaction unit can be at least one of a tubular reactor, a tower reactor, or a tank reactor, preferably a tower reactor.

[0060] A fourth aspect of the present invention provides a system for producing needle coke from catalytic slurry oil, comprising:

[0061] The purification unit is used to receive and process the catalytic oil slurry, and the purified oil slurry is obtained after processing.

[0062] The hydrogenation reaction unit is used to receive hydrogen and purified oil slurry obtained from the purification unit, and a hydrogenation reaction is carried out under the action of a hydrogenation catalyst.

[0063] The gas-liquid separation unit is used to receive the reaction effluent from the hydrogenation reaction unit and separate it to obtain gaseous and liquid products.

[0064] The first fractionation unit is used to receive the liquid product from the gas-liquid separation unit and fractionate it to obtain light oil, middle distillate oil and tail oil.

[0065] The cracking reaction unit receives the middle distillate oil from the first fractionation unit, and the resulting cracking products are mixed with the tail oil from the first fractionation unit as the first feedstock.

[0066] The coking unit is used to receive the first and second raw materials, and after reaction, needle coke is obtained;

[0067] The second fractionation unit is used to receive coking oil and gas from the coking unit, and after fractionation, it yields tar gas, light coking oil, and heavy coking oil.

[0068] Furthermore, in the above-mentioned system for producing needle coke from catalytic oil slurry, the purification unit can adopt one or a combination of several methods such as filtration, centrifugal sedimentation, flocculation sedimentation, and vacuum distillation, with filtration being preferred. The further filtration equipment can be one or a combination of several methods such as sintered metal powder filter cartridges, metal wire mesh filter cartridges, and ceramic membrane filter cartridges, with ceramic membrane filter cartridges being preferred.

[0069] Furthermore, in the aforementioned system for producing needle coke from catalytic slurry oil, the hydrogenation reaction unit includes at least one hydrogenation reactor. When two or more hydrogenation reactors are used, there are no particular restrictions on the connection method between the reactors; they are generally connected in series. 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.

[0070] Furthermore, in the above-mentioned system for producing needle coke from catalytic oil slurry, the gas-liquid separation unit can be any of the devices capable of achieving gas-liquid two-phase separation. Generally, the gas-liquid separation unit includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, and a cold low-pressure separator.

[0071] Furthermore, in the above-mentioned system for producing needle coke from catalytic slurry, the first fractionation unit includes at least one fractionation tower, which can be either a packed tower or a plate tower.

[0072] Furthermore, in the above-mentioned system for producing needle coke from catalytic slurry, the cracking reaction unit is equipped with at least one reactor, which can be one or a combination of tubular reactors, tower reactors, and tank reactors, with tower reactors being preferred.

[0073] Furthermore, in the above-mentioned system for producing needle coke from catalytic oil slurry, the second fractionation unit includes at least one fractionation tower, which can be either a packed tower or a plate tower.

[0074] Furthermore, the aforementioned system for producing needle coke from catalytic oil slurry includes a condensation reaction unit, which receives light oil from the fractionation unit. The reaction products obtained from the condensation reaction are separated to obtain top oil and bottom oil. Generally, the bottom oil 5% distillation temperature is controlled at 300℃~420℃, preferably 330℃~370℃. The top oil can be discharged directly from the unit or returned as a diluent to the purification unit to be mixed with the catalytic oil slurry for purification treatment. The bottom oil is recycled back to the fractionation unit and processed together with the liquid products obtained from the gas-liquid separation unit. The condensation reaction unit can be at least one of a tubular reactor, a tower reactor, or a tank reactor, preferably a tower reactor.

[0075] Furthermore, in the above-mentioned catalytic slurry production needle system, the coking unit can adopt a delayed coking device, which generally has at least one heating furnace and at least two coking towers, and always keeps at least one coking tower in the reaction stage and at least one coking tower in the decoking stage.

[0076] Compared with existing technologies, the method and system for producing needle coke feedstock using catalytic slurry oil provided by this invention have the following advantages:

[0077] (1) The method of this invention optimizes the molecular structure of the feedstock for needle coke production from the perspective of molecular refining. The method involves cracking the relatively small-molecule middle distillate after hydrogenation, and then blending the cracking products with the larger-molecule tail oil as the feedstock for needle coke. The cracking products generate less gas and light oil during coking, resulting in less disturbance to the reaction system. The blending of cracking products and tail oil ensures a moderate amount of light components in the system, preventing excessive disturbance, while also promoting the directional arrangement of condensed macromolecules. This effectively mitigates the impact of small-molecule hydrocarbon generation on needle coke performance during delayed coking. It avoids the problem of excessive gas and light oil generation during needle coke production using only hydrogenated slurry oil as feedstock, which leads to significant disturbance to the system and poor needle coke performance. Simultaneously, it solves the problem of large amounts of small-molecule hydrocarbons being generated during the coking process of hydrogenated slurry oil. On the one hand, the continuous escape of small molecule hydrocarbons disturbs the reaction system, which is not conducive to the formation of a broad-area mesophase; on the other hand, some small molecule hydrocarbons, such as monocyclic aromatic hydrocarbons, may not be able to escape and can only remain in the system to undergo condensation reactions. In the later stage of needle coke preparation, during the coke pulling and solidification stage, a large number of small molecule hydrocarbons escape rapidly, resulting in a large number of gaps in the solidified system and a high porosity of the needle coke.

[0078] (2) In the method of the present invention, all fractions of the catalytic slurry are hydrogenated. The five-ring and above aromatic hydrocarbons contained in the catalytic slurry are hydrogenated, fractionated, and cracked in sequence. After hydrogenation, these aromatic hydrocarbons are converted into tetracyclic aromatic hydrocarbons with saturated side chains, or even tricyclic aromatic hydrocarbons with saturated side chains. These aromatic hydrocarbons are further cracked to convert into tetracyclic or tricyclic aromatic hydrocarbons with short side chains (ideal components for needle coke feedstock), which can maximize the effective utilization of the five-ring and above aromatic hydrocarbons in the catalytic slurry. In the prior art, the catalytic slurry is usually fractionated and a suitable fraction is selected for hydrogenation, or a suitable fraction is selected after hydrogenation as feedstock for needle coke production. As a result, the five-ring and above aromatic hydrocarbons in the catalytic slurry are not rationally utilized and cannot be used as feedstock for needle coke production. The method of this invention can convert the five-ring and above aromatic hydrocarbons in the catalytic oil slurry into needle coke feedstock, thereby improving the effective utilization efficiency of the catalytic oil slurry, increasing the yield of needle coke feedstock and needle coke, and enhancing the economic value of the catalytic oil slurry.

[0079] (3) The method of the present invention can reduce the heat load of the coking unit. In the prior art, hydrogenated oil slurry is directly used as feed for the coking unit. Under the conditions of needle coke preparation, the cracking reaction such as the breaking of side chains of aromatic molecules is an endothermic reaction. The small molecules generated will also take away a lot of heat when they escape, resulting in a low temperature of the reaction system. In order to promote the condensation of aromatic molecules into large molecules, it is necessary to continuously increase the outlet temperature of the coking furnace so as to bring more heat into the coke tower. In the method of the present invention, by blending the cracking products and tail oil, the molecular composition of the first feedstock is controlled, and the reaction depth of the first stage of the coking reaction is improved. In the second stage of the coking reaction, the second feedstock is coking heavy oil with weaker cracking ability, which can effectively provide heat to the system and improve the quality of needle coke products. Attached Figure Description

[0080] Figure 1 This is a schematic diagram of the method and system for producing needle coke feedstock using catalytic oil slurry according to the present invention.

[0081] Figure 2 This is a schematic diagram of the method and system for producing needle coke from catalytic oil slurry according to the present invention. Detailed Implementation

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] In this paper, the ash content of the oil was determined by the GB / T 508 method, the sulfur content was determined by the SH / T 0689 method, and the aromatic carbon content was determined by the SH / T 0793 method.

[0088] In this paper, the needle-shaped tap density samples were prepared according to the requirements of GB / T 1997, and at least 150g of 1mm to 2mm particles were screened and determined by the GB / T 21354 method; the particle strength was determined by the method in Appendix B of T / ZGTS 002.

[0089] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this article are based on weight, and pressure is gauge pressure.

[0090] A specific embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0091] like Figure 1 and Figure 2As shown, the specific process of the method for producing needle coke feedstock and needle coke from catalytic slurry provided by the present invention is as follows: Catalytic slurry 1 is first purified by purification unit 2, and the resulting purified slurry 9 is mixed with hydrogen 12 and enters hydrogenation reaction unit 3, where it contacts the hydrogenation catalyst to carry out a hydrogenation reaction. The hydrogenation reaction effluent 10 enters gas-liquid separation unit 4 for separation, and after separation, gaseous product 11 and liquid product 13 are obtained. Gaseous product 11 is compressed by hydrogen compressor 5 and sent to hydrogenation reaction unit 3 as recycled hydrogen 12; liquid product 13 enters the first fractionation unit 6 for separation, and after separation, light oil 14, middle distillate oil 15 and tail oil 16 are obtained. In this process, light oil 14 is either discharged from the reactor or enters the condensation reaction unit 7 for condensation reaction. The reaction products are separated to obtain top oil 19 and bottom oil 20. Top oil 19 is discharged from the top of the reactor and can be used as a diluent to mix with catalytic slurry 1 and sent to purification unit 2. Bottom oil 20 obtained from the condensation reaction is returned to the first fractionation unit 6 for processing. Middle distillate oil 15 is sent to the cracking reaction unit 8, where it undergoes a cracking reaction under the action of carrier gas 17 to obtain cracking product 18. In the first stage of the coking reaction, the mixture of tail oil 16 and cracking product 18 is used as the first feedstock for producing needle coke and enters coking units 22A / 22B. After the reaction, coking oil gas 23 and needle coke product 24 are obtained. Coking oil gas 23 enters the second fractionation unit 25 and is separated to obtain coking gas 26, coking light oil 27 and coking heavy oil 21. In the second stage of the coking reaction, coking heavy oil 21 is used as the second feedstock for producing needle coke and enters coking units 22A / 22B.

[0092] The properties of the catalytic slurry used in the embodiments and comparative examples of this invention are shown in Table 1. The hydrogenation catalyst used is FZC-34BT (developed by the Dalian Research Institute of Petrochemical Technology, Sinopec). The purification unit uses a filter, and the carrier gas is steam.

[0093] Example 1

[0094] Example 1 describes a method for producing needle coke feedstock and needle coke using catalytic slurry provided by this invention. The catalytic slurry undergoes desolidification and purification in a purification unit, resulting in purified slurry that enters a hydrogenation reaction unit. The hydrogenation effluent is separated into liquid products in a gas-liquid separation unit. The liquid products enter a first fractionation unit to separate light oil, middle distillate oil, and tail oil. The light oil is discharged, while the middle distillate oil is sent to a cracking reaction unit. The cracking products and tail oil are mixed at a mass ratio of 2:8 and used as the first feedstock for needle coke production in a coking unit. The resulting needle coke is deposited at the bottom of the tower. The coking gas enters a second fractionation unit to separate coking gas, light coking oil, and heavy coking oil. The heavy coking oil is returned to the coking unit as the second feedstock.

[0095] The conditions for hydrogenation, cracking, and coking reactions are listed in Table 2; the properties of the first feedstock are listed in Table 3. The yield of needle coke based on catalytic oil slurry is listed in Table 4.

[0096] Example 2

[0097] Example 2 follows the same process as Example 1, differing only in some operating parameters. The conditions for hydrogenation, cracking, and coking reactions are listed in Table 2; the properties of the first feedstock are listed in Table 3. The yield of needle coke based on catalytic oil slurry is listed in Table 4.

[0098] Example 3 (Normal)

[0099] Example 3 follows the same process as Example 1, differing only in some operating parameters. The conditions for hydrogenation, cracking, and coking reactions are listed in Table 2. The properties of the first feedstock are listed in Table 3. The yield of needle coke based on catalytic slurry is listed in Table 4.

[0100] Example 4

[0101] Example 4 follows the same process as Example 1, except that light oil enters the condensation reaction unit. The condensation reaction conditions are: reaction temperature 412℃, reaction pressure 0.9MPa, residence time 2.3h. The condensation catalyst is: alumina as support, 7.0wt%ZrO2-4.5wt%MoO2 as active components, clover-shaped structure. The condensation reaction product enters the first fractionation unit.

[0102] The conditions for hydrogenation, cracking, and coking reactions are listed in Table 2. The properties of the primary feedstock are listed in Table 3. The yield of needle coke based on catalytic oil slurry is listed in Table 4.

[0103] Comparative Example 1

[0104] After being purified by the purification unit, the catalytic slurry enters the hydrogenation reaction unit. The hydrogenation effluent is separated into liquid products in the gas-liquid separation unit. The liquid products enter the first fractionation unit to separate light oil, middle distillate oil, and tail oil. The middle distillate oil is used as the first feedstock for producing needle coke and enters the coking unit. The needle coke obtained after the reaction is deposited at the bottom of the tower. The coking gas enters the second fractionation unit to separate coking gas, light coking oil, and heavy coking oil. The heavy coking oil is returned to the coking unit as the second feedstock.

[0105] The conditions for hydrogenation and coking reactions are listed in Table 2. The properties of the first feedstock are listed in Table 3. The yield of needle coke based on catalytic oil slurry is listed in Table 4.

[0106] Comparative Example 2

[0107] After being purified by the purification unit, the catalytic slurry is fed into the first fractionation unit to separate light oil, middle distillate oil, and tail oil. The middle distillate oil enters the hydrogenation reaction unit, and the effluent from the hydrogenation reaction is separated into liquid products in the gas-liquid separation unit. The liquid products are sent to the second fractionation unit as the first raw material for producing needle coke, and together with the circulating oil, they are sent to the coking unit at a circulation ratio of 0.8. The needle coke obtained after the coking reaction is deposited at the bottom of the tower, and the coking oil and gas enter the second fractionation unit to separate coking gas and coking light oil, which are then discharged from the unit.

[0108] The conditions for hydrogenation and coking reactions are listed in Table 2. The properties of the first feedstock are listed in Table 3. The yield of needle coke based on catalytic oil slurry is listed in Table 4.

[0109] Comparative Example 3

[0110] After being purified by the purification unit, the catalytic slurry enters the hydrogenation reaction unit. The hydrogenation effluent is separated into liquid products in the gas-liquid separation unit. The liquid products enter the first fractionation unit to separate light oil and tail oil. The tail oil is used as the first feedstock for the production of needle coke and enters the coking unit. The needle coke obtained after the reaction is deposited at the bottom of the tower. The coking oil and gas enter the second fractionation unit to separate coking gas, light coking oil, and heavy coking oil. The heavy coking oil is returned to the coking unit as the second feedstock.

[0111] The conditions for hydrogenation and coking reactions are listed in Table 2. The properties of the first feedstock are listed in Table 3. The yield of needle coke based on catalytic oil slurry is listed in Table 4.

[0112] The needle coke obtained in the above examples and comparative examples was calcined at 1350℃, and the tap density and particle strength were tested. The results are shown in Table 4.

[0113] Table 1 Properties of Catalytic Slurry

[0114]

[0115] Table 2 Reaction conditions for each unit in the examples

[0116]

[0117] Table 3 Properties of the First Raw Material

[0118]

[0119] Table 4. Reaction results of the Examples and Comparative Examples

[0120]

[0121] *Based on the quality of purified oil slurry.

Claims

1. A method for producing needle coke feedstock from catalytic slurry oil, the method comprising the following: (1) After purification, the catalytic oil slurry enters the hydrogenation reaction unit together with hydrogen. Under the action of the hydrogenation catalyst, a hydrogenation reaction occurs. The reaction effluent is separated to obtain gaseous products and liquid products. (2) The liquid product obtained in step (1) is fractionated by the first fractionation unit to obtain light oil, middle distillate oil and tail oil; the 5% distillation temperature of the middle distillate oil is 340℃~430℃, and the 95% distillation temperature is 440℃~530℃. (3) The middle distillate oil obtained in step (2) is sent to the cracking reaction unit for cracking reaction. The cracking products obtained are mixed with the tail oil obtained in step (2) and used as the first raw material for producing needle coke. The reaction conditions of the cracking reaction unit are: reaction temperature of 380℃~520℃, reaction pressure of 0.1MPa~5MPa, and residence time of 0.01h~30h.

2. The method for producing needle coke feedstock from catalytic slurry oil according to claim 1, characterized in that: In step (1), the ash content of the catalytic oil slurry is higher than 0.01 wt%, the sulfur content is higher than 0.4 wt%, and the aromatic carbon content is not less than 60 mol.

3. The method for producing needle coke feedstock from catalytic slurry oil according to claim 1, characterized in that: In step (1), the sulfur content of the catalytic oil slurry is higher than 0.8 wt%, and the aromatic carbon content is 65 mol% to 90 mol%.

4. The method for producing needle coke feedstock by catalytic slurry oil according to claim 1, characterized in that: In step (1), the purification process employs one or more of the following methods: filtration, centrifugal sedimentation, flocculation sedimentation, and vacuum distillation.

5. The method for producing needle coke feedstock from catalytic slurry oil according to claim 1, characterized in that: The purification process in step (1) uses filtration.

6. The method for producing needle coke feedstock by catalytic slurry oil according to claim 1, characterized in that: After purification, the ash content of the catalytic oil slurry is no more than 0.01 wt%.

7. The method for producing needle coke feedstock by catalytic slurry oil according to claim 1, characterized in that: After purification, the ash content of the catalytic oil slurry is no more than 0.005 wt%.

8. The method for producing needle coke feedstock by catalytic slurry oil according to claim 1, characterized in that: The hydrogenation reaction conditions in step (1) are as follows: reaction temperature 300℃~480℃, reaction pressure 2MPa~20MPa, hydrogen-to-oil volume ratio 100~2500, and liquid hourly space velocity 0.1h. -1 ~2.0h -1 .

9. The method for producing needle coke feedstock from catalytic slurry oil according to claim 1, characterized in that: The hydrogenation reaction conditions in step (1) are as follows: reaction temperature 330℃~390℃, reaction pressure 4MPa~8MPa, hydrogen-to-oil volume ratio 500~1800, and liquid hourly space velocity 0.7h. -1 ~1.2h -1 .

10. The method for producing needle coke feedstock by catalytic slurry oil according to claim 1, characterized in that: The liquid product in step (1) refers to the liquid fraction after the naphtha fraction has been removed.

11. The method for producing needle coke feedstock from catalytic slurry oil according to claim 1, characterized in that: The light oil obtained in step (2) can be directly discharged from the device as a product, or enter the condensation reaction unit for reaction, or part of it can be discharged from the device as a product and the remainder can enter the condensation reaction unit for reaction.

12. The method for producing needle coke feedstock from catalytic slurry oil according to claim 11, characterized in that: The condensation reaction conditions are: reaction temperature of 350℃~550℃, reaction pressure of 0.1MPa~5MPa, and residence time of 0.01h~50h.

13. The method for producing needle coke feedstock from catalytic slurry oil according to claim 11, characterized in that: The condensation reaction conditions are: reaction temperature of 400℃~460℃, reaction pressure of 0.8MPa~3.0MPa, and residence time of 0.3h~24h.

14. The method for producing needle coke feedstock from catalytic slurry oil according to claim 11, characterized in that: The reaction products obtained from the condensation reaction are separated to obtain top oil and bottom oil. The bottom oil is 5% distilled at a temperature of 300℃~420℃.

15. The method for producing needle coke feedstock from catalytic slurry oil according to claim 11, characterized in that: The reaction products obtained from the condensation reaction are separated to obtain top oil and bottom oil. The bottom oil is 5% distilled at a temperature of 330℃~370℃.

16. The method for producing needle coke feedstock from catalytic slurry oil according to claim 14 or 15, characterized in that: The top oil is discharged directly from the device, or it is used as a diluent to be mixed with the catalytic oil slurry in step (1) for purification; the bottom oil is recycled back and processed together with the liquid product obtained in step (1).

17. The method for producing needle coke feedstock by catalytic slurry oil according to claim 11, characterized in that: A condensation catalyst is added during the condensation reaction, and the condensation reaction is carried out under the action of the condensation catalyst. The condensation catalyst includes a support and an active component. The support is one or more of kaolin, montmorillonite, alumina, and silica-containing alumina. The active component is at least one of oxides of Group IVB and / or Group VIB metals. The content of the active component is 0.1wt% to 50wt% based on the weight of the catalyst.

18. The method for producing needle coke feedstock from catalytic slurry oil according to claim 11, characterized in that: A condensation catalyst is added during the condensation reaction, and the condensation reaction is carried out under the action of the condensation catalyst. The condensation catalyst includes a support and an active component, wherein the support is alumina and the active component is at least one oxide of a Group IVB and / or Group VIB metal; the content of the active component is 5wt% to 25wt% based on the weight of the catalyst.

19. The method for producing needle coke feedstock from catalytic slurry oil according to claim 1, characterized in that: In step (2), the 5% distillation temperature of the middle distillate is 355℃~410℃, and the 95% distillation temperature is 460℃~505℃.

20. The method for producing needle coke feedstock by catalytic slurry oil according to claim 1, characterized in that: The reaction conditions for the cracking reaction unit are: reaction temperature of 420℃~490℃, reaction pressure of 0.2MPa~1.0MPa, and residence time of 0.1h~3h.

21. The method for producing needle coke feedstock by catalytic slurry oil 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; the mass ratio of middle distillate oil to carrier gas is 100:0.1 to 100:

20.

22. The method for producing needle coke feedstock by catalytic slurry oil according to claim 1, characterized in that: During the cracking reaction, a carrier gas, which is water vapor, is introduced; the mass ratio of middle distillate oil to carrier gas is 100:1 to 100:

8.

23. The method for producing needle coke feedstock from catalytic slurry oil according to claim 1, characterized in that: The mass ratio of cracking products to tail oil in step (3) is 1:9 to 9:

1.

24. The method for producing needle coke feedstock by catalytic slurry oil according to claim 1, characterized in that: The mass ratio of cracking products to tail oil in step (3) is 4:6 to 8:

2.

25. The method for producing needle coke feedstock from catalytic slurry oil according to claim 1, characterized in that: The aromatic carbon content of the first raw material in step (3) is 60 mol% to 90 mol%.

26. The method for producing needle coke feedstock by catalytic slurry oil according to claim 1, characterized in that: The aromatic carbon content of the first raw material in step (3) is 65 mol% to 85 mol%.

27. A method for producing needle coke from catalytic slurry oil, the method comprising the following: (1) After purification, the catalytic oil slurry enters the hydrogenation reaction unit together with hydrogen. Under the action of the hydrogenation catalyst, a hydrogenation reaction occurs. The reaction effluent is separated to obtain gaseous products and liquid products. (2) The liquid product obtained in step (1) is fractionated by the first fractionation unit to obtain light oil, middle distillate oil and tail oil; the 5% distillation temperature of the middle distillate oil is 340℃~430℃, and the 95% distillation temperature is 440℃~530℃. (3) The middle distillate oil obtained in step (2) is sent to the cracking reaction unit for cracking reaction. The cracking products obtained are mixed with the tail oil obtained in step (2) and used as the first raw material for producing needle coke. The reaction conditions of the cracking reaction unit are: reaction temperature of 380℃~520℃, reaction pressure of 0.1MPa~5MPa, and residence time of 0.01h~30h. (4) The first raw material obtained in step (3) is sent to the coking unit. The coking oil and gas obtained from the reaction are separated by the second fractionation unit to obtain coking gas, coking light oil and coking heavy oil. The coking heavy oil is returned to the coking unit as the second raw material for producing needle coke.

28. The method for producing needle coke from catalytic slurry oil according to claim 27, characterized in that: The coking unit in step (4) is 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.

29. The method for producing needle coke from catalytic slurry oil according to claim 28, characterized in that: The outlet temperature of the heating furnace is 410℃~550℃, and the heating rate is controlled at 0.5℃ / h~30℃ / h; the top pressure of the coke tower is 0.01MPa~2.5MPa, and it can be operated under constant pressure or variable pressure. When using variable pressure operation, the pressure changing rate is controlled at 0.1MPa / h~5MPa / h; the reaction cycle is 10h~96h.

30. The method for producing needle coke from catalytic slurry oil according to claim 28, characterized in that: The outlet temperature of the heating furnace is 440℃~520℃, and the heating rate is controlled at 3℃ / h~8℃ / h; the top pressure of the coke tower is 0.2MPa~1.3MPa, and it can be operated under constant pressure or variable pressure. When using variable pressure operation, the pressure changing rate is controlled at 0.1MPa / h~5MPa / h; the reaction cycle is 32h~54h.

31. The method for producing needle coke from catalytic slurry oil according to claim 27, characterized in that: The 5% distillation temperature of the coking heavy oil in step (4) is 280℃~380℃.

32. The method for producing needle coke from catalytic slurry oil according to claim 27, characterized in that: The 5% distillation temperature of the coking heavy oil in step (4) is 310℃~360℃.

33. The method for producing needle coke from catalytic slurry oil according to claim 27, characterized in that: In step (4), the coking reaction is divided into two stages. The first raw material is introduced in the first stage and the second raw material is introduced in the second stage. In each reaction stage, from the beginning to the end of the reaction stage, the corresponding raw material oil is continuously added, and the raw material oil that is not corresponding to the reaction stage is not added.

34. The method for producing needle coke from catalytic slurry oil according to claim 33, characterized in that: In step (4), the reaction time of the first stage of the coking reaction is the first 20% to 80% of the reaction cycle, and the reaction time of the second stage is the last 20% to 80% of the reaction cycle; the end point of the first stage is the start point of the second stage.

35. The method for producing needle coke from catalytic slurry oil according to claim 33, characterized in that: In step (4), the reaction time of the first stage of the coking reaction is the first 35% to 70% of the reaction cycle, and the reaction time of the second stage is the last 40% to 60% of the reaction cycle; the end point of the first stage is the start point of the second stage.

36. A system for producing needle coke feedstock from catalytic slurry oil using the method of any one of claims 1-26, comprising: The purification unit is used to receive and process the catalytic oil slurry, and the purified oil slurry is obtained after processing. The hydrogenation reaction unit is used to receive hydrogen and purified oil slurry obtained from the purification unit, and a hydrogenation reaction is carried out under the action of a hydrogenation catalyst. The gas-liquid separation unit is used to receive the reaction effluent from the hydrogenation reaction unit and separate it to obtain gaseous and liquid products. The first fractionation unit is used to receive the liquid product from the gas-liquid separation unit and fractionate it to obtain light oil, middle distillate oil and tail oil. The cracking reaction unit is used to receive the middle distillate oil from the first fractionation unit, and after the reaction, the cracking products are mixed with the tail oil from the first fractionation unit as the first feedstock.

37. The system for producing needle coke feedstock from catalytic slurry oil according to claim 36, characterized in that: The purification unit employs one or more of the following methods: filtration, centrifugal sedimentation, flocculation sedimentation, and vacuum distillation.

38. The system for producing needle coke feedstock by catalytic slurry oil according to claim 36, characterized in that: The purification unit uses filtration, and the filtration equipment is one or a combination of several of the following: sintered metal powder filter cartridge, metal wire mesh filter cartridge, and ceramic membrane filter cartridge.

39. The system for producing needle coke feedstock from catalytic slurry oil according to claim 38, characterized in that: The filtration equipment is a ceramic membrane filter.

40. The system for producing needle coke feedstock by catalytic slurry oil according to claim 36, characterized in that: The hydrogenation reaction unit is equipped with at least one hydrogenation reactor. When two or more hydrogenation reactors are set up, the reactors are connected in series. The hydrogenation reactor is selected from one or more of the following: fluidized bed reactor, suspended bed reactor, and fixed bed reactor.

41. The system for producing needle coke feedstock by catalytic slurry oil according to claim 40, characterized in that: The hydrogenation reactor is a fixed-bed reactor.

42. The system for producing needle coke feedstock by catalytic slurry oil according to claim 36, characterized in that: The gas-liquid separation unit can be any of the devices that can achieve gas-liquid two-phase separation. The gas-liquid separation unit includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, and a cold low-pressure separator.

43. The system for producing needle coke feedstock from catalytic slurry oil according to claim 36, characterized in that: The first fractionation unit includes at least one fractionation tower, which is either a packed tower or a plate tower.

44. The system for producing needle coke feedstock by catalytic slurry oil according to claim 36, characterized in that: The cracking reaction unit is equipped with at least one reactor, which is one or more of the following: tubular reactor, tower reactor, and tank reactor.

45. The system for producing needle coke feedstock from catalytic slurry oil according to claim 44, characterized in that: The reactor is a tower reactor.

46. ​​The system for producing needle coke feedstock by catalytic slurry oil according to claim 36, characterized in that: It includes a condensation reaction unit for receiving light oil from the first fractionation unit. The reaction products obtained from the condensation reaction are separated to obtain top oil and bottom oil. The condensation reaction unit adopts at least one of tubular reactor, tower reactor, and tank reactor.

47. The system for producing needle coke feedstock from catalytic slurry oil according to claim 46, characterized in that: The condensation reaction unit uses a tower reactor.

48. A system for producing needle coke from catalytic slurry using the method of any one of claims 27-35, comprising: The purification unit is used to receive and process the catalytic oil slurry, and the purified oil slurry is obtained after processing. The hydrogenation reaction unit is used to receive hydrogen and purified oil slurry obtained from the purification unit, and a hydrogenation reaction is carried out under the action of a hydrogenation catalyst. The gas-liquid separation unit is used to receive the reaction effluent from the hydrogenation reaction unit and separate it to obtain gaseous and liquid products. The first fractionation unit is used to receive the liquid product from the gas-liquid separation unit and fractionate it to obtain light oil, middle distillate oil and tail oil. The cracking reaction unit is used to receive the middle distillate oil from the first fractionation unit, and after the reaction, the cracking products are mixed with the tail oil from the first fractionation unit as the first feedstock. The coking unit is used to receive the first and second raw materials, and after reaction, needle coke is obtained; The second fractionation unit is used to receive coking oil and gas from the coking unit, and after fractionation, it yields tar gas, light coking oil, and heavy coking oil.

49. The system for producing needle coke from catalytic slurry oil according to claim 48, characterized in that: The second fractionation unit includes at least one fractionation tower, which is either a packed tower or a plate tower.

50. The system for producing needle coke from catalytic slurry oil according to claim 48, characterized in that: The coking unit employs a delayed coking device, equipped with at least one heating furnace and at least two coke towers, and always keeps at least one coke tower in the reaction stage and at least one coke tower in the decoking stage.

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