A method for processing catalytic oil slurry

Abstract

The invention discloses a method for processing catalytic oil slurry, the method comprising subjecting the catalytic oil slurry to a vacuum distillation system to separate and obtain light fraction oil and heavy fraction oil; the light fraction oil is subjected to thermal polycondensation, purification treatment, and refining to obtain mesophase asphalt, and the oil and gas products after the reaction enter a fractionation system for separation to obtain gas, gasoline, diesel, and circulating oil; the heavy fraction oil is subjected to thermal polycondensation to obtain asphalt containing mesophase carbon microspheres, and the mesophase carbon microspheres and heavy oil are obtained after separation, purification, and drying, and the heavy oil and the light fraction oil are mixed and enter a subsequent process to produce mesophase asphalt. The method uses the catalytic oil slurry to produce mesophase asphalt and mesophase carbon microspheres, thereby improving the utilization rate of the catalytic oil slurry and the added value of the product.

Description

Technical Field

[0001] The invention relates to a method for processing catalytic oil slurry, in particular to a method for co-producing mesophase asphalt and mesophase carbon microspheres by using catalytic oil slurry. Background Art

[0002] Mesophase pitch is a nematic liquid crystal with a certain amount of mesophase content formed by heat treatment of organic compounds such as petroleum asphalt. Because of its typical anisotropy and spinnability, it is used as a precursor for a variety of high-end carbon materials, such as mesophase pitch-based carbon fiber, needle coke, foamed carbon, etc.

[0003] Mesophase carbon microspheres have a wide range of applications in new energy, metallurgy, chemical industry, environmental protection and other fields due to their unique molecular layer structure and good conductivity. With the rise of the new energy industry this year, mesophase carbon microspheres have gradually become the preferred material for lithium battery negative electrodes.

[0004] At present, catalytic oil slurry is mainly used as a low-sulfur marine fuel blending component or for the production of road asphalt, etc., with low economic benefits. Since the molecular weight distribution of catalytic oil slurry is wide, the fraction with higher molecular weight can form a mesophase at a lower temperature due to its high reaction activity, while the fraction with lower molecular weight can form a mesophase at a higher temperature for a longer time. This will lead to the use of full-fraction oil slurry as a raw material to produce mesophase asphalt. The product properties in the system are not uniform, and the system contains lighter components and mesophase asphalt at the same time. Even the system may contain coke due to the high-activity fraction reaction depth, which seriously affects the quality of mesophase asphalt. CN106544758A, CN107163970A, CN107189802A, CN107216903A, etc. all use the fraction obtained by vacuum distillation of FCC oil slurry to produce mesophase asphalt by means of thermal polycondensation, co-carbonization, cross-linking modification, etc., but other components have not been well utilized. Summary of the invention

[0005] In view of the deficiencies in the prior art, the main purpose of the present invention is to provide a process for the co-production of mesophase asphalt and mesophase carbon microspheres. The method uses the light components in the catalytic oil slurry to produce mesophase asphalt, and the heavy components to produce mesophase carbon microspheres. The production method greatly improves the utilization rate of raw materials.

[0006] The present invention provides a method for processing catalytic oil slurry, the method comprising the following contents:

[0007] (1) The catalytic oil slurry enters the vacuum distillation system to separate into light distillate oil and heavy distillate oil, which enter the light distillate oil and heavy distillate oil collection tanks respectively; the light distillate oil is heated by the heating furnace and enters the first thermal reaction unit to react to generate oil and gas products and mesophase asphalt-rich products, and the oil and gas products enter the fractionation system to separate into gas, gasoline, diesel and circulating oil 1;

[0008] (2) The mesophase asphalt product obtained in step (1) enters the refining and purification unit for purification and then enters the second thermal reaction unit. The generated oil and gas products enter the fractionation system for separation to obtain gas, gasoline, diesel and circulating oil 2. Part of the generated mesophase asphalt product exits the device and part enters the third thermal reaction unit.

[0009] (3) The heavy fraction oil obtained in step (1) is mixed with part of the mesophase asphalt from step (2) and then enters the third thermal reaction unit to react to generate oil gas and a heavy oil product containing mesophase carbon microspheres. The oil gas product enters the fractionation system and is separated to obtain gas, gasoline, diesel and cycle oil 3;

[0010] (4) The heavy oil product containing mesophase carbon microspheres generated in step (3) enters the separation unit, and after separation, the mesophase carbon microspheres and heavy oil are obtained. The mesophase carbon microspheres exit the device, and the heavy oil is heated in the heating furnace together with the light fraction oil in step (1) and enters the first thermal reaction unit.

[0011] In step (1) of the method of the present invention, the catalytic slurry is preferably a catalytic cracking slurry of naphthenic crude oil.

[0012] In step (1) of the method of the present invention, the catalytic oil slurry is subjected to vacuum distillation to obtain light and heavy distillate oils, wherein 90% distillation temperature of the light distillate oil is controlled to be 480°C-540°C, preferably 500°C-520°C.

[0013] In step (1) of the method of the present invention, the light fraction oil and the heavy oil are mixed and heated in a heating furnace before entering the first thermal reaction unit, and the outlet temperature of the heating furnace is controlled to be 450°C-520°C, preferably 460°C-500°C.

[0014] In step (1) of the method of the present invention, the first thermal reaction unit is an adiabatic reactor, the outside of the thermal reaction unit is an insulation layer, and the thickness of the insulation layer is 100-400 mm, preferably 150-300 mm.

[0015] In step (1) of the method described in the present invention, no stirring component and no filler may be provided inside the first thermal reaction unit.

[0016] In step (1) of the method of the present invention, the aspect ratio of the first thermal reaction unit is 4-20, preferably 5-15.

[0017] In step (1) of the method of the present invention, the light fraction oil and the heavy oil are mixed and heated in a heating furnace before entering the first thermal reaction unit, and the materials enter the reactor from the middle and upper part of the first thermal reaction unit.

[0018] In step (1) of the method of the present invention, the feed is a mixture of light distillate oil and heavy oil in step (4), which is heated in a heating furnace and enters a first thermal reaction unit, wherein the ratio of light distillate oil to heavy oil is 1-10:1, preferably 1-5:1, the residence time in the first thermal reaction unit is 6-40h, preferably 10-36h, and the reaction pressure is normal pressure-2MPa, preferably 0.2-1MPa.

[0019] In step (2) of the method described in the present invention, the mesophase-rich asphalt product enters the second thermal reaction unit after passing through the refining and purification unit, and the refining and purification unit is an adsorption and / or filtration unit. The quinoline insoluble matter QI in the crystallized material is controlled to be ≤10wt%, preferably QI≤8wt%, specifically 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, and the ash content is ≤50ppm, preferably ash content≤40ppm, specifically 5ppm, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm. The adsorbent used in the adsorption unit can be one or more of the hydrogenation catalysts discarded from industrial devices, preferably the hydrogenation refining catalyst regenerated after discarding. The filtration unit uses a screen to filter, and the screen can be set to multiple layers. The number of meshes of the screen increases along the direction of logistics, and the number of meshes of the last screen is more than 1000.

[0020] In the above method, the refining and purification unit used in one or more embodiments includes an adsorption and filtration unit, which can be arranged in one reactor or in different reactors, preferably in one reactor, and the adsorption and filtration units are arranged in sequence along the logistics direction. The adsorbent used in the adsorption unit is a hydrogenation catalyst discarded from an industrial device, preferably a hydrogenation refining catalyst regenerated after being discarded, and the catalyst can be arranged in one or more layers; the filtration unit is provided with multiple layers of screens, and the mesh number of the screens is 50 to 1000 meshes.

[0021] In the above method, the material is subjected to a temperature reduction treatment before entering the refining and purification unit, and the temperature is reduced to 320-400°C, preferably 350-380°C.

[0022] In step (2) of the method described in the present invention, the refining and purification unit comprises at least two identical refining and purifying devices, one of which is always kept in working state and the other in standby state.

[0023] In step (2) of the method described in the present invention, the second thermal reaction unit is a thin film evaporator, molecular distillation, or short path distillation, preferably a thin film evaporator.

[0024] In step (2) of the method described in the present invention, the operating conditions of the second thermal reaction unit are: film thickness 0.03-1 mm, preferably 0.05-0.8 mm, film temperature 360-420° C., preferably 390-410° C., pressure 6 Pa-1 atm (absolute), preferably 7-100 Pa (absolute), residence time 30-500 s, preferably 90-300 s, and the evaporation area is determined according to the processing volume.

[0025] In step (2) of the method described in the present invention, the mesophase pitch can be directly fed into the spinning machine for spinning.

[0026] In step (3) of the method described in the present invention, the heavy distillate oil obtained in step (1) is mixed with part of the mesophase asphalt obtained in step (2) and then enters the third thermal reaction unit, wherein the mesophase asphalt from step (2) and the heavy distillate oil obtained in step (1) are mixed in a ratio of 1-10:100, preferably 2-5:100.

[0027] In step (3) of the method described in the present invention, the heavy fraction oil obtained in step (1) is mixed with part of the intermediate phase asphalt from step (2) and then enters the third thermal reaction unit. Preferably, the two are mixed evenly in a buffer tank before entering the third thermal reaction unit, wherein stirring and heat preservation facilities are provided in the buffer tank.

[0028] In step (3) of the method of the present invention, the heavy fraction oil obtained in step (1) is mixed with part of the mesophase asphalt from step (4) and then enters the third thermal reaction unit. The third thermal reaction unit is a tubular reactor or a kettle reactor, preferably a tubular reactor.

[0029] In step (3) of the method described in the present invention, the operating conditions of the third thermal reaction unit are: reaction temperature 400-480°C, preferably 410-450°C, reaction pressure 1-3MPa, preferably 1-2MPa, residence time 1-20h, preferably 4-10h.

[0030] In step (4) of the method of the present invention, the heavy oil product containing mesophase carbon microspheres generated in step (3) enters a separation unit. The separation unit may be one of high-temperature centrifugal separation and solvent extraction, preferably solvent extraction. The separated mesophase carbon microspheres are dried and then discharged from the device.

[0031] In step (4) of the method described in the present invention, the heavy oil is mixed with the light fraction oil in step (1), and after being heated in a heating furnace, enters a first thermal reaction unit to react to generate oil and gas products and a mesophase asphalt-rich product. The oil and gas products enter a fractionation system for separation to obtain gas, gasoline, diesel and circulating oil, and the mesophase asphalt-rich product enters a refining and purification unit.

[0032] Compared with the prior art, the co-production process of mesophase pitch and mesophase carbon microspheres of the present invention has the following beneficial effects:

[0033] 1. The process for the co-production of mesophase asphalt and mesophase carbon microspheres provided by the present invention utilizes the characteristics that mesophase carbon microspheres and mesophase asphalt are in different stages of the reaction process, and the formation of mesophase asphalt requires that the distillation range distribution of raw materials cannot be too wide, and cuts the catalytic oil slurry into light distillate oil and heavy distillate oil, which are respectively used to produce mesophase asphalt and mesophase carbon microspheres. The heavy oil after the separation of the mesophase carbon microspheres can continue to be used to produce mesophase asphalt, thereby realizing the comprehensive utilization of the catalytic oil slurry, greatly improving the raw material utilization rate of the catalytic oil slurry, and increasing the added value.

[0034] 2. In the process for the co-production of mesophase asphalt and mesophase carbon microspheres provided by the present invention, the first thermal reaction unit is an adiabatic reactor. Thermal cracking and condensation reactions occur in the first thermal reaction unit using the heat from the heating furnace, thereby avoiding the problem of coking of materials on the inner wall of the reactor due to high reactor wall temperature caused by external heating of a conventional reactor, which causes some coke particles to be dispersed into the product, seriously affecting the quality of the mesophase asphalt product.

[0035] 3. In the process for the co-production of mesophase asphalt and mesophase carbon microspheres provided by the present invention, the first reaction product has a higher content of light components. The presence of light components will greatly reduce the viscosity of the first reaction product and improve its fluidity. The first reaction product can be directly refined and purified without treatment such as distillation, which can ensure that the system is purified at a lower viscosity. The coke particles will be better dispersed in the waste catalyst bed and intercepted by the screen. On the one hand, the system has a lower viscosity, good fluidity and a higher purification efficiency. On the other hand, the purification quality is higher.

[0036] 4. The co-production process method of mesophase asphalt and mesophase carbon microspheres provided by the present invention directly performs a refining and purification treatment on the first thermal reaction product during the production of the mesophase asphalt. After the mesophase asphalt leaves the device, it can directly enter the spinning machine for spinning, which can not only achieve continuous production and improve the quality of the mesophase asphalt, but also avoid the product clogging the fluid channel of the mesophase asphalt melt during the spinning production process, resulting in discontinuity in the spinning production, thereby improving the spinnability of the mesophase asphalt and the performance stability of the carbon fiber.

[0037] 5. The co-production process of mesophase pitch and mesophase carbon microspheres provided by the present invention uses the hydrorefining waste catalyst bed as the first purification process of the refining purification unit, and uses the waste catalyst to precipitate coke particles that may exist in the first reaction product, thereby realizing waste utilization.

[0038] 6. In the process for the co-production of mesophase asphalt and mesophase carbon microspheres provided by the present invention, a thin film evaporator is selected as the second thermal reaction unit, which can separate the light components in the product from the mesophase asphalt in a short time and rapidly increase the mesophase asphalt content in the product.

[0039] 7. The present invention provides a method for the co-production of mesophase asphalt and mesophase carbon microspheres. On the one hand, the mesophase asphalt generated from the same raw material is used as a nucleating agent for the mesophase carbon microspheres to promote the formation of the mesophase small balls. On the other hand, the mesophase carbon microspheres are produced from the heavy fraction of the catalytic oil slurry. In the process of forming the mesophase carbon microspheres, the mechanical impurities and original quinoline insolubles in the heavy fraction can be gathered in the mesophase carbon microspheres, so that the impurity and insoluble content in the heavy oil after the carbon microspheres are separated is reduced, and the heavy oil can be used as a raw material for the production of mesophase asphalt, thereby realizing the purification and refining of the heavy fraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a co-production process of mesophase asphalt and mesophase carbon microspheres of the present invention. DETAILED DESCRIPTION

[0041] The method of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the following embodiments do not constitute a limitation of the method of the present invention.

[0042] like Figure 1As shown, the present invention provides a method for the co-production of mesophase asphalt and mesophase carbon microspheres. Catalytic oil slurry 1 enters a vacuum distillation system 2, and is separated to obtain light fraction oil 3 and heavy fraction oil 4, which enter a light fraction collecting tank 5 and a heavy fraction collecting tank 6 respectively. The light fraction oil 3 and the heavy fraction oil are reacted and separated to obtain heavy oil 29. After being heated, the heavy oil 29 enters a heating furnace 8 through a pipeline 7, and then enters a first thermal reaction unit 10 through a pipeline 9. The reaction generates an oil and gas product 11 and a mesophase asphalt-rich product 12. The oil and gas product enters a fractionating tower 18 and is separated to obtain a gas 19, gasoline 20, diesel 21 and circulating oil 22. The mesophase asphalt-rich product is refined and purified by a purification unit 1. After treatment, the oil enters the second thermal reaction unit 15 through pipeline 14 to continue the reaction, and the reaction produces oil and gas products 16 and mesophase asphalt products 17. The oil and gas products enter the fractionation system 18 for separation; the heavy fraction oil is mixed with part of the mesophase asphalt product 23 through pipeline 24 and enters the third thermal reaction unit 25 for reaction to generate oil and gas products 26 and products containing mesophase carbon microspheres 27. The oil and gas products enter the fractionation system 18 for separation, and the products containing mesophase carbon microspheres enter the purification and refining unit 28 to separate heavy oil 29 and mesophase carbon microspheres 30. The heavy oil and light fraction oil are mixed and then enter the heating furnace for further reaction, and the mesophase carbon microspheres exit the device.

[0043] The raw materials used in the examples and comparative examples of the present invention are refined oil slurry, and the specific properties are shown in Table 1.

[0044] Table 1 Raw material properties

[0045]

[0046] Example 1

[0047] use Figure 1 The process method for the co-production of mesophase asphalt and mesophase carbon microspheres shown in the figure uses catalytic oil slurry from a refinery with ash removed as raw material. The specific properties of the oil slurry are analyzed in Table 1. The raw oil is subjected to a vacuum distillation device to obtain light and heavy distillate oils, wherein the distillation temperature of 90% of the light distillate oil is controlled to be 500°C. The heavy oil obtained after separation of the light distillate oil and the third thermal reaction product is mixed in a ratio of 2:1, and enters the first thermal reaction unit after being heated in a heating furnace. The outlet temperature of the heating furnace is controlled to be 460°C, the pressure of the first thermal reaction unit is 1MPa, and the residence time is 30h. The oil and gas products generated by the reaction enter the fractionation system and are separated into gas, gasoline, diesel and circulating oil. The first reaction product is cooled to 350°C by a quencher or after heat exchange with the material, and then enters the refining and purification unit for purification. The upper part of the refining and purification unit is the adsorption unit, and the lower part is the filtration unit. The adsorbent used in the adsorption unit is the regenerated hydrorefining catalyst after being discarded (the active components of the discarded deactivated catalyst are Mo and Ni, with Mo content of 17.0wt%, Ni content of 4.23wt%, and the rest is carrier alumina; the physical and chemical properties of the deactivated catalyst are as follows: specific surface area of ​​63.4m2 ·g -1 Compared with the fresh catalyst, the specific surface area decreased by 50%; the pore volume was 0.37cm 3 ·g -1 Compared with the fresh agent, the pore volume decreased by 40%; the waste deactivated catalyst was charred at a regeneration temperature of 450°C; the filtration unit used screen filtration, and the screen mesh numbers along the logistics direction were 50 mesh, 200 mesh, 500 mesh and 1000 mesh respectively. The QI content of the purified product after treatment is 7.0wt%, and the ash content is 30ppm; the purified product enters the second thermal reaction unit, and continues to react under the conditions of film thickness 0.8mm, film temperature 390℃, pressure 100Pa, and residence time 300s. The oil and gas products generated by the reaction enter the fractionation system for separation, and part of the intermediate phase asphalt product exits the device, and part of it is fully mixed with the heavy distillate oil obtained by vacuum distillation of the raw material in a ratio of 5:100, and then enters the third thermal reaction unit, and continues to react under the conditions of reaction temperature of 410℃, pressure of 2MPa, and residence time of 10h. The oil and gas generated by the reaction enter the fractionation system for separation, and the product containing intermediate phase carbon microspheres enters the solvent extraction separation unit, and is extracted and separated at a ratio of product to solvent (quinoline) of 1:3 and a temperature of 80℃. The solid phase is washed and dried to obtain intermediate phase carbon microspheres, and the liquid phase is recovered by solvent to obtain heavy oil. The heavy oil and light distillate oil are mixed and heated in a heating furnace and then enter the first thermal reaction unit for reaction.

[0048] Example 2

[0049] use Figure 1 The co-production process shown in the figure has slightly adjusted operating conditions compared with Example 1: the outlet temperature of the heating furnace is 480°C, the residence time of the material in the first thermal reaction unit is 24h, and the other conditions are the same as Example 1.

[0050] Example 3

[0051] use Figure 1 The co-production process shown in the figure has slightly adjusted operating conditions compared with Example 1. The light distillate oil and heavy oil are mixed in a 1:1 ratio and then enter the heating furnace. The outlet temperature of the heating furnace is 500°C, the pressure of the first thermal reaction unit is 2MPa, the residence time is 20h, and other conditions are the same as Example 1.

[0052] Example 4

[0053] use Figure 1 The co-production process shown in the figure has slightly adjusted operating conditions compared with Example 1. The operating conditions of the third thermal reaction unit are: reaction temperature of 450°C, pressure of 2MPa, residence time of 6h, and other conditions are the same as Example 1.

[0054] Comparative Example 1

[0055] Compared with Example 1, no refining and purification unit is provided, and the first reaction product directly enters the second thermal reaction unit after being cooled, and other conditions are the same as those in Example 1.

[0056] Comparative Example 2

[0057] Compared with Example 1, the mesophase asphalt obtained in the second thermal reaction unit is directly discharged from the device, and the material entering the third thermal reaction unit is only heavy fraction oil. Other conditions are the same as in Example 1.

[0058] In the present invention, the test standards for various performance indicators are as follows: the asphalt softening point is determined according to the GB / T 2294-2019 method; the ash content is determined according to the GB / T 2295-2018 method; the quinoline insoluble matter is determined according to the GB / T 2293-2019 method; the mesophase content is determined by a polarizing microscope; the spinnability is tested on a single-hole spinning machine by melt spinning using the products obtained in the embodiments and comparative examples as precursor asphalt; the yield of mesophase carbon microspheres is calculated based on the heavy distillate oil.

[0059] Table 2 Properties of mesophase asphalt products

[0060]

[0061] Table 3 Properties of mesophase carbon microspheres

[0062]

Claims

1. A method for processing catalytic oil slurry, characterized in that: The method includes the following contents: (1) The catalytic oil slurry enters the vacuum distillation system to separate into light distillate oil and heavy distillate oil, which enter the light distillate oil and heavy distillate oil collection tanks respectively; the light distillate oil is heated by the heating furnace and enters the first thermal reaction unit to react to generate oil and gas products and mesophase asphalt-rich products, and the oil and gas products enter the fractionation system to separate into gas, gasoline, diesel and circulating oil 1; (2) The mesophase asphalt product obtained in step (1) enters the refining and purification unit for purification and then enters the second thermal reaction unit. The generated oil and gas products enter the fractionation system for separation to obtain gas, gasoline, diesel and circulating oil 2. Part of the generated mesophase asphalt product exits the device and part enters the third thermal reaction unit. (3) The heavy fraction oil obtained in step (1) is mixed with part of the mesophase asphalt from step (2) and then enters the third thermal reaction unit to react to generate oil gas and a heavy oil product containing mesophase carbon microspheres. The oil gas product enters the fractionation system and is separated to obtain gas, gasoline, diesel and cycle oil 3; (4) The heavy oil product containing mesophase carbon microspheres generated in step (3) enters the separation unit, and after separation, the mesophase carbon microspheres and heavy oil are obtained. The mesophase carbon microspheres are discharged from the device, and the heavy oil is heated in the heating furnace together with the light fraction oil in step (1) and enters the first thermal reaction unit; In step (1), the catalytic oil slurry is subjected to vacuum distillation to obtain light and heavy distillate oils, wherein the distillation temperature of 90wt% of the light distillate oil is controlled to be 480°C-540°C; In step (1), the first thermal reaction unit is an adiabatic reactor; in step (2), the second thermal reaction unit is a thin film evaporator; In step (2), the mesophase asphalt-rich product enters the second thermal reaction unit after passing through a refining and purification unit, wherein the refining and purification unit is an adsorption and / or filtration unit, and controls the quinoline insoluble matter QI in the crystallized material to be ≤10wt% and the ash content to be ≤50ppm.

2. The method according to claim 1, characterized in that: In step (1), the catalytic oil slurry is catalytic cracking oil slurry of naphthenic crude oil.

3. The method according to claim 1, characterized in that: In step (1), the distillation temperature of 90wt% of the light fraction oil is controlled to be 500°C-520°C.

4. The method according to claim 1, characterized in that: In step (1), the light fraction oil is heated in a heating furnace and then enters the first thermal reaction unit, and the outlet temperature of the heating furnace is controlled to be 450°C-520°C.

5. The method according to claim 1, characterized in that: In step (1), the light fraction oil is heated in a heating furnace and then enters the first thermal reaction unit, and the outlet temperature of the heating furnace is controlled to be 460°C-500°C.

6. The method according to claim 1, characterized in that: In step (1), the first thermal reaction unit is an adiabatic reactor, and the outside of the thermal reaction unit is an insulation layer with a thickness of 100-400 mm.

7. The method according to claim 1, characterized in that: In step (1), the first thermal reaction unit is an adiabatic reactor, and the outside of the thermal reaction unit is an insulation layer with a thickness of 150-300 mm.

8. The method according to claim 1, characterized in that: In step (1), the light fraction oil is heated in the heating furnace and then enters the first thermal reaction unit, and the light fraction oil enters the reactor from the middle and upper part of the first thermal reaction unit.

9. The method according to claim 1, characterized in that: In step (1), the feed is a mixed feed of light distillate oil and heavy oil in step (4), wherein the ratio of light distillate oil to heavy oil is 1-10:10, the residence time is 6-40h, and the reaction pressure is normal pressure-1MPa.

10. The method according to claim 9, characterized in that: In step (1), the ratio of light fraction oil to heavy oil is 1-5:10, the residence time is 10-36h, and the reaction pressure is 0.2-0.5MPa.

11. The method according to claim 1, characterized in that: In step (2), the quinoline insoluble matter QI in the crystallized material is controlled to be ≤8wt% and the ash content is ≤40ppm.

12. The method according to claim 11, characterized in that: The material is cooled to 320-400℃ before entering the refining and purification unit.

13. The method according to claim 12, characterized in that: The material is cooled to 350-380℃ before entering the refining and purification unit.

14. The method according to claim 1, characterized in that: In step (2), the operating conditions of the second thermal reaction unit are: film thickness 0.03-1 mm, film temperature 360-420° C., pressure 6 Pa-1 atm, and residence time 30-500 s.

15. The method according to claim 14, characterized in that: In step (2), the operating conditions of the second thermal reaction unit are: film thickness 0.05-0.8 mm, film temperature 390-410° C., pressure 7-100 Pa, and residence time 90-300 s.

16. The method according to claim 1, characterized in that: In step (3), the heavy distillate oil obtained in step (1) is mixed with part of the mesophase asphalt obtained in step (2) and then enters the third thermal reaction unit, wherein the mesophase asphalt from step (2) and the heavy distillate oil obtained in step (1) are mixed in a mass ratio of 1-10:

100.

17. The method according to claim 16, characterized in that: In step (3), the mesophase asphalt from step (2) and the heavy distillate oil obtained in step (1) are mixed in a mass ratio of 2-5:

100.

18. The method according to claim 1, characterized in that: In step (3), the heavy fraction oil obtained in step (1) is mixed with part of the mesophase asphalt from step (2) and then enters the third thermal reaction unit, wherein the two are mixed evenly in a buffer tank before entering the third thermal reaction unit.

19. The method according to claim 1, characterized in that: In step (3), the heavy fraction oil obtained in step (1) is mixed with part of the mesophase asphalt from step (4) and then enters a third thermal reaction unit, which is a tubular reactor or a kettle reactor.

20. The method according to claim 19, characterized in that: The third thermal reaction unit is a tubular reactor.

21. The method according to claim 1, characterized in that: In step (3), the operating conditions of the third thermal reaction unit are: reaction temperature 400-480°C, reaction pressure 1-3MPa, and residence time 1-20h.

22. The method according to claim 21, characterized in that: In step (3), the operating conditions of the third thermal reaction unit are: reaction temperature 410-450°C, reaction pressure 1-2MPa, and residence time 4-10h.

23. The method according to claim 1, characterized in that: In step (4), the heavy oil product containing mesophase carbon microspheres generated in step (3) enters a separation unit, which is one of high-temperature centrifugal separation and solvent extraction. The separated mesophase carbon microspheres are dried and then discharged from the device.

24. The method according to claim 23, characterized in that: In step (4), the separation unit is solvent extraction.

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