CN115678587A - Method and device for preparing mesophase pitch - Google Patents
Method and device for preparing mesophase pitch Download PDFInfo
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- CN115678587A CN115678587A CN202110861095.6A CN202110861095A CN115678587A CN 115678587 A CN115678587 A CN 115678587A CN 202110861095 A CN202110861095 A CN 202110861095A CN 115678587 A CN115678587 A CN 115678587A
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Abstract
A method and apparatus for preparing mesophase pitch, said method comprises sending the heavy oil raw materials into the polymerization reactor after heating through the heating furnace, after reacting for 3-24 hours at 400-480 duC, enter the flash tank and isolate the distillate oil with boiling point less than 350 duC, the other supplies are sent into the distillation column of reducing pressure, isolate the distillate oil with boiling point less than 480-550 duC in the distillation column of reducing pressure; and (3) feeding the material at the bottom of the reduced pressure distillation tower into a heating furnace for thermal conversion, and finally feeding the material into an asphalt granulator to contact with nitrogen for spray granulation to obtain mesophase asphalt. The method and the device provided by the invention have the characteristics of simple process flow and easy control of process conditions, and solve the problem of difficult material taking caused by high viscosity of the mesophase pitch.
Description
Technical Field
The present invention relates to a heavy oil processing method and apparatus, and more particularly, to a method and apparatus for producing mesophase pitch.
Background
According to the difference of spinning raw materials, carbon fibers can be classified into polyacrylonitrile-based carbon fibers and pitch-based carbon fibers. Pitch-based carbon fibers can be classified into general-grade pitch-based carbon fibers and high-performance pitch-based carbon fibers according to the kind of pitch. Polyacrylonitrile-based carbon fibers are currently the most common carbon fiber products, and can be classified into strength series (T series) and modulus series (M series) according to their mechanical properties. The strength series can reach 3000-11000MPa according to different grade marks. The modulus series can reach 930GPa according to different grade marks. At present, the production condition of domestic polyacrylonitrile-based carbon fibers is better, and the production cost is gradually reduced along with the continuous development of large-tow carbon fiber technology. The general-purpose asphalt-based carbon fiber is prepared by using isotropic asphalt as a spinning raw material, has low mechanical property, generally has strength lower than 1000MPa and modulus lower than 150GPa, and is not usually used for structural materials; the composite material has the characteristics of low cost, corrosion resistance, heat insulation and the like, is generally used for building materials and heat insulation materials, and can be produced in a large scale at home at present. The high-performance asphalt-based carbon fiber has the main performance characteristics of high modulus which can reach 930GPa at most, the highest modulus in the material which can be produced in mass at present, the theoretical modulus of the graphite material is more than 90%, and the high-performance asphalt-based carbon fiber has an irreplaceable position in a use scene of pursuing the modulus.
The high-performance pitch-based carbon fiber has a series of excellent performances such as high strength, high modulus, high temperature resistance, low density and the like, and is widely applied to multiple fields such as military affairs, aviation, aerospace electronic devices, high-end industrial equipment and the like. For the reasons, the export of high-performance pitch-based carbon fiber and composite material thereof, precursor thereof (spinning pitch), related production technology and production device thereof to China is strictly limited by carbon fiber reinforcement in the United states and the like, the development of related industries is severely limited, and the production technology becomes a neck technology which limits high-end manufacture in China. Therefore, autonomous research and development is imperative.
The research and development work in the field starts earlier in China, but the industrialization progress is slower. Since the nineties, domestic enterprises have built production lines for many times and tried to produce, but all the domestic enterprises stop producing because of no qualified spinning asphalt supply. Therefore, the current production situation of the industry in China is that a production line exists, but the qualified high-quality spinning asphalt does not exist.
CN201810089036.X discloses a coal tar pitch refining method for synthesizing mesophase pitch, which separates effective components of coal tar pitch from impurities such as residual coal dust coke particles in raw coal tar pitch under normal pressure, and the obtained refined coal tar pitch can be used as a high-end carbon material.
CN201911039222.3 discloses a preparation method of a high thermal conductivity mesophase pitch-based carbon fiber and a high quality mesophase pitch, in which graphene, a hydrogen donor and purified coal tar pitch are mixed, a thermal polycondensation reaction is directly performed in an autoclave to prepare mesophase pitch, and the prepared mesophase pitch can be used to prepare carbon fiber with excellent mechanical properties and heat transfer conductivity.
CN201910901067.5 discloses a preparation method of spinning-grade synthetic mesophase pitch, which comprises the steps of adding ZrCl2 serving as a catalyst into a pure aromatic compound to react for 2-5 hours at the temperature of 200-320 ℃ to prepare an aromatic oligomer; dissolving the product by using pyridine, filtering to remove the solid catalyst, and recovering the solvent pyridine by distillation to obtain an aromatic hydrocarbon oligomer without the catalyst; finally, the low polymer of the aromatic hydrocarbon is subjected to thermal polycondensation reaction for 10 to 20 hours at 390 to 420 ℃ to prepare the mesophase pitch.
In summary, although many academic researches on mesophase pitch preparation methods are developed domestically, most of the researches are focused on chemical methods, reaction processes and laboratory-level researches, the development on process flows is less, and feasible process flow schemes are not provided for Chinese amplification and engineering amplification.
Disclosure of Invention
One of the technical problems to be solved by the invention is to provide a method for preparing mesophase pitch based on the prior art, wherein the method has simple flow and easily controlled process conditions.
The second technical problem to be solved by the invention is to provide a device for preparing mesophase pitch, which has a simple structure and can realize the method.
A method for preparing mesophase pitch, send the heavy oil raw materials into the polymerization reactor after heating through the heating furnace, after reacting for 3-24 hours at 400-480 duC, enter the flash tank and isolate the distillate oil with boiling point less than 350 duC, the other supplies are sent into the vacuum distillation column, isolate the distillate oil with boiling point less than 480-550 duC in the vacuum distillation column; and (3) feeding the material at the bottom of the reduced pressure distillation tower into a heating furnace for thermal conversion, and finally feeding the material into an asphalt granulator to contact with nitrogen for spray granulation to obtain mesophase asphalt.
A raw material pipeline is communicated with a polymerization reaction kettle, a flash tank and a reduced pressure distillation tower through a heating furnace, and a tower bottom outlet of the reduced pressure distillation tower is communicated with an asphalt granulator through the heating furnace; wherein, two material pipelines are arranged in the heating furnace, one is a raw material pipeline, and the other is a discharge pipeline at the bottom of the decompression tower; the polymerization reactor is internally provided with an electric heating rod, and the outside of the polymerization reactor is provided with an electric heating sleeve; the asphalt granulator is provided with a nitrogen inlet and a nitrogen outlet.
The method and the device for preparing the mesophase pitch have the beneficial effects that:
the method for preparing the mesophase pitch is suitable for the characteristics of the generation process of the mesophase pitch, on one hand, the high-pressure reaction fully utilizes the low-boiling-point components, improves the viscosity of the system and ensures the growth and fusion of the mesophase; on the other hand, the high-pressure reaction utilizes the hydrogen transfer reaction of the low-boiling-point component to replace the hydrotreating process, has the characteristics of simple operation and easy control of process conditions, and solves the problem of difficult material taking caused by high viscosity of the mesophase pitch. The mesophase pitch prepared by the method provided by the invention has better quality.
The device for preparing the mesophase pitch is used for realizing the method, and has the advantages of low device construction cost, simple process flow and easy control of process conditions.
Drawings
FIG. 1 is a schematic flow diagram of a method for producing mesophase pitch according to the present invention.
FIG. 2 is a schematic flow diagram of a process of a comparative example.
Wherein:
2-a raw material tank; 2. 6, 8-heavy oil pump; 3, heating the furnace; 4-a polymerization reaction kettle; 5-a flash tank; 7-a reduced pressure distillation column; 9-asphalt granulator.
Detailed Description
The following describes specific embodiments of the present invention in detail.
A method for preparing mesophase pitch, send the heavy oil raw materials into the polymerization reactor after heating through the heating furnace, after reacting for 3-24 hours at 400-480 duC, enter the flash tank and isolate the distillate oil with boiling point less than 350 duC, the other supplies are sent into the vacuum distillation column, isolate the distillate oil with boiling point less than 480-550 duC in the vacuum distillation column; and (3) feeding the material at the bottom of the reduced pressure distillation tower into a heating furnace for thermal conversion, and finally feeding the material into an asphalt granulator to contact with nitrogen for spray granulation to obtain mesophase asphalt.
In the method for preparing the mesophase pitch, the heavy oil raw material is a heavy oil product rich in polycyclic aromatic hydrocarbons, and the content of the polycyclic aromatic hydrocarbons is more than 80wt%;
preferably, the heavy oil raw material is selected from one or a mixture of several of catalytic slurry oil, furfural extract oil, coal tar produced by coal chemical industry at low temperature, medium temperature and high temperature.
Preferably, the distillation range of the heavy oil raw material is in the range of 350-500 ℃, and the heavy oil raw material is a specific fraction obtained after vacuum distillation of a heavy oil product. Preferably, the heavy oil feedstock is a distillate having a distillation range of 350-400 ℃,400-450 ℃,400-460 ℃,450-500 ℃,400-430 ℃,430-460 ℃ or 460-490 ℃. Further preferably a fraction having a distillation range of 400 to 450 ℃,400 to 460 ℃,400 to 430 ℃ and 430 to 460 ℃.
Heavy oil raw materials such as catalytic oil slurry, furfural extract oil, coal chemical by-products such as low-temperature, medium-temperature and high-temperature coal tar contain certain heteroatoms such as sulfur, nitrogen and oxygen, which are not beneficial to the formation of an intermediate phase and the form of the intermediate phase. In order to improve the quality of the mesophase pitch, the heavy oil raw material is preferably contacted with a hydrotreating catalyst in a hydrogenation reactor to carry out a hydrotreating reaction, so as to reduce the content of heteroatoms. The sulfur content of the heavy oil raw material after hydrotreating is not more than 0.25 percent, and the nitrogen content is not more than 0.25 percent. More preferably, the oxygen content is not more than 0.4%.
Optionally, if the solid content in the raw material is higher, the solid content of the heavy oil raw material after solid removal is less than 20 mug/g, and the solid content needs to be removed before entering the raw material tank.
Preferably, the heavy oil raw material is heated by a heating furnace, and the material temperature at the outlet of the heating furnace is 450-500 ℃; more preferably, the temperature of the furnace exit material is 470-480 ℃.
In the method provided by the invention, the hydrocarbon cracking reaction and the aromatic polymerization reaction occur simultaneously in the polymerization reaction kettle, the hydrocarbon cracking reaction is endothermic, and the aromatic polymerization reaction is exothermic. Previous experimental studies have shown that the reaction in autoclaves is generally endothermic and requires timely addition of heat to maintain the temperature constant. The method selects a high-pressure kettle as a polymerization reactor, an electric heating rod is arranged in the high-pressure kettle, an electric heating sleeve is arranged outside the high-pressure kettle, and the temperature of materials in the polymerization kettle is kept constant under the combined action of internal heating and external heating.
Along with the rise of the system temperature and the progress of the reaction, the hydrocarbon is cracked into small molecular gas, and the pressure of the reaction kettle is gradually increased due to the adoption of a closed mode in the high-pressure polymerization kettle. Due to the higher system, gasoline fraction, diesel oil fraction and wax oil fraction generated by cracking heavy oil products are kept in a liquid phase, so that the viscosity of the liquid phase is favorably reduced, the system is prevented from local overheating and coking, the fusion of mesophase spherule is favorably realized, and meanwhile, the lower viscosity is favorable for conveying reaction products to a flash tank.
The reaction temperature of the polymerization reaction kettle is 400-480 ℃, preferably the reaction temperature is 440-460 ℃, preferably, the materials are in a batch reaction mode in the polymerization reaction kettle, and the reaction residence time is 3-24 hours, preferably 3-11 hours. Generally, a long residence time at low temperature is beneficial to the growth of the mesophase molecular crystal structure, and the prepared mesophase pitch has better quality.
The apparatus provided by the present invention may be a pilot plant level experimental apparatus or an industrial production apparatus.
Preferably, the vacuum distillation column separates a fraction having a boiling point of less than 520 to 535 ℃.
Preferably, the overhead temperature of the reduced pressure distillation tower is 270-290 ℃, and the operation pressure is not more than 10mmHg.
Preferably, the tower bottom material of the reduced pressure distillation tower is sent into a heating furnace for short-residence-time thermal conversion, the outlet temperature of the heating furnace is 460-480 ℃, and the residence time in the heating furnace is 120-300 seconds.
Preferably, in the asphalt granulator, the material at the bottom of the reduced pressure distillation tower after passing through the heating furnace contacts with low-temperature nitrogen for spray granulation, and the nitrogen is preferably introduced at normal temperature and the operating pressure of 0.2-0.4MPa.
In the method provided by the invention, the heating furnace heats two materials, one is raw oil, and the other is asphalt after pressure reduction and deep drawing.
A raw material feeding pipeline is communicated with a polymerization reaction kettle, a flash tank and a reduced pressure distillation tower through a heating furnace, and a tower bottom outlet of the reduced pressure distillation tower is communicated with an asphalt granulator through the heating furnace; wherein, two pipelines are passed through the heating furnace, one is a raw material feeding pipeline, and the other is a discharge pipeline passing through the bottom of the decompression tower; the polymerization reactor is internally provided with an electric heating rod, and the outside of the polymerization reactor is provided with an electric heating sleeve; the asphalt granulator is provided with a nitrogen inlet and a nitrogen outlet.
Preferably, a heavy oil pump is arranged on the raw material feeding pipeline, the connecting pipeline between the flash tank and the reduced pressure distillation tower, and the connecting pipeline between the bottom of the reduced pressure tower and the heating furnace.
The invention will be further elucidated with reference to the drawing, which is only a preferred embodiment of the invention and is not to be construed as limiting the invention.
FIG. 1 is a schematic flow diagram of a method for preparing mesophase pitch according to the present invention. As shown in figure 1, heavy oil raw material stored in a raw material tank 1 is conveyed by a heavy oil pump 2 through a pipeline to enter a heating furnace 3, the temperature is raised after heating, and the temperature of the material at the outlet of the heating furnace is 450-500 ℃. The heated materials enter a polymerization reaction kettle 4 for reaction, an intermittent reaction mode is adopted in the polymerization reaction kettle, the reaction temperature is 400-480 ℃, and the reaction is stopped by reducing the temperature of the polymerization kettle after a period of reaction. The generated product enters a flash tank 5 through a pipeline to be flashed and separated to obtain light fraction with the boiling point of less than 350 ℃, micromolecular hydrocarbon generated by cracking is discharged from the top of the flash tank 5, and the material at the bottom of the flash tank 5 enters a reduced pressure distillation tower 7 through a heavy oil pump 6. The material is decompressed and distilled in a decompression distillation tower 7, the decompression cutting temperature is 480-550 ℃, distillate oil is discharged from the top of the decompression distillation tower 7, the material at the bottom of the decompression distillation tower 7 enters a heating furnace 3 through a pipeline by a heavy oil pump 8 for thermal conversion with short retention time, and the temperature of the pipeline at the outlet of the heating furnace is 450-480 ℃. Then enters an asphalt granulator 9 to contact with low-temperature nitrogen for granulation, and an intermediate phase asphalt product is obtained.
In the device for preparing the mesophase pitch shown in the attached figure 1, a raw material feeding pipeline is communicated with a polymerization reaction kettle 4, a flash evaporation tank 5 and a reduced pressure distillation tower 7 through a heating furnace 3, and a tower bottom outlet of the reduced pressure distillation tower 7 is communicated with a pitch granulator 9 through the heating furnace 3; wherein, the heating furnace 3 heats two materials which are not communicated with each other; an electric heating rod is arranged in the polymerization reactor 4, and an electric heating sleeve is arranged outside the polymerization reactor; the asphalt granulator 9 is provided with a low-temperature nitrogen inlet and a low-temperature nitrogen outlet.
The following examples further illustrate the effectiveness of the process of the invention for preparing mesophase pitch, but the invention is not limited thereto.
In the examples and comparative examples, heavy feed oil was obtained from a catalytic slurry oil obtained as a by-product from a wax oil catalytic cracking unit of Yanshan division, petrochemical company, ltd., china, and was cut into narrow fractions of 400 to 450 ℃ and the composition thereof was as shown in Table 1.
The analysis method comprises the following steps:
the hydrocarbon composition of the oil was measured according to the petrochemical industry Standard "determination of hydrocarbons in saturated hydrocarbon fraction in gas oil (Mass Spectrometry) (SH/T0659-1998)".
The contents of carbon, hydrogen, sulfur and nitrogen elements in the oil are measured according to the petrochemical industry standard ' elemental analyzer method for measuring carbon, hydrogen and nitrogen in petroleum products and lubricants ' (SH/T0656-2017) '.
The oxygen content of the oil is determined by cracking the sample in a pyrolysis tube containing carbon powder, wherein the oxygen-containing compound is quantitatively converted into carbon monoxide. The carrier gas carries the cleavage product to a series of scrubbers to remove acid gases and water vapor. And finally, detecting the product by an infrared detector.
Carbon residue was measured according to the national Standard "determination of carbon residue in Petroleum products" (GB/T17144-1997).
The observation method of the mesophase morphology is that firstly 4 to 5g of mesophase pitch samples are inlaid in the epoxy resin, and curing agent polyene polyamine is added; then after the epoxy resin is cured, carrying out metallographic polishing on the surface of the embedded sample; and finally, carrying out polarization-dependent reflection observation on the polished surface by using a polarization microscope, and measuring the content of the mesophase by using graphic processing software.
Examples 1-3 illustrate the effectiveness of the process of the present invention for producing mesophase pitch.
Example 1
Example 1 the process flow shown in FIG. 1 is employed to illustrate the case where the polymerization reactor temperature of the heavy feed oil is 440 ℃ and the polymerization time is 8 hours.
The heavy raw oil stored in the raw material tank 1 is conveyed by the heavy oil pump 2 and enters the heating furnace 3 through a pipeline, and the temperature of the material at the outlet of the heating furnace is 460 ℃. The materials enter a polymerization reaction kettle 4 for reaction, the reaction temperature is 440 ℃, and the reaction is stopped by reducing the temperature of the polymerization kettle after the polymerization time is 8 hours. The product formed enters the flash tank 5 through a line, and the flash tank 5 is operated at 350 ℃. And discharging the small-molecular hydrocarbons generated by cracking from the top of the flash tank 5, and feeding the materials at the bottom of the flash tank 5 into a reduced-pressure distillation tower 7 through a heavy oil pump 6. The materials are subjected to reduced pressure distillation in a reduced pressure distillation tower 7, the reduced pressure cutting temperature is 535 ℃, distillate oil is discharged from the top of the reduced pressure distillation tower 7, the materials at the bottom of the reduced pressure distillation tower 7 enter a heating furnace 3 through a pipeline by a heavy oil pump 8 for thermal conversion with short retention time, the retention time is 100 seconds, and the material temperature of the materials at the bottom of the reduced pressure distillation tower at the outlet of the heating furnace is 480 ℃. Then the mixture enters an asphalt granulator 9 to contact with nitrogen at normal temperature for granulation, and a mesophase asphalt product is obtained.
The operating conditions are listed in Table 2 and the product properties are listed in Table 3.
Example 2
Example 2 the flow chart of FIG. 1 was employed to describe the case where the polymerization reactor was used for a polymerization time of 4 hours at a temperature of 450 ℃ for heavy feed oil.
The heavy raw oil stored in the raw material tank 1 is conveyed by the heavy oil pump 2 and enters the heating furnace 3 through a pipeline for heating, and the temperature of the material at the outlet of the heating furnace is 460 ℃. The materials enter a polymerization reaction kettle 4 for reaction, the reaction temperature is 450 ℃, and the reaction is stopped by reducing the temperature of the polymerization kettle after 4 hours of polymerization time. The product formed enters the flash tank 5 through a line, and the flash tank 5 is operated at 350 ℃. And discharging the small molecular hydrocarbons generated by cracking from the top of the flash tank 5, and feeding the rest materials at the bottom of the flash tank 5 into a reduced pressure distillation tower 7 through a heavy oil pump 6. The materials are subjected to reduced pressure distillation in a reduced pressure distillation tower 7, the reduced pressure cutting temperature is 530 ℃, distillate oil is discharged from the top of the reduced pressure distillation tower 7, the materials at the bottom of the reduced pressure distillation tower 7 enter a heating furnace 3 through a heavy oil pump 8 through a pipeline for thermal conversion with short retention time, the retention time is 90 seconds, and the temperature of the material pipeline at the bottom of the heating furnace is 470 ℃. Then the mixture enters an asphalt granulator 9 to contact with nitrogen at normal temperature for granulation, and a mesophase asphalt product is obtained.
The operating conditions are listed in Table 2 and the product properties are listed in Table 3.
Example 3
Example 3 the flow chart of FIG. 1 was employed to describe the case where the polymerization temperature of the polymerization vessel was 460 ℃ and the polymerization time was 4 hours.
The heavy raw oil stored in the raw material tank 1 is conveyed by a heavy oil pump 2 and enters a heating furnace 3 through a pipeline, and the temperature of the heated material at the outlet of the heating furnace is 480 ℃. The materials enter a polymerization reaction kettle 4 for reaction, the reaction temperature is 460 ℃, and the reaction is stopped by reducing the temperature of the polymerization kettle after 4 hours of polymerization time. The product formed enters the flash tank 5 through a line, and the flash tank 5 is operated at 350 ℃. And discharging the small molecular hydrocarbons generated by cracking from the top of the flash tank 5, and feeding the materials at the bottom of the flash tank 5 into a reduced pressure distillation tower 7 through a heavy oil pump 6. The materials are subjected to reduced pressure distillation in a reduced pressure distillation tower 7, the reduced pressure cutting temperature is 525 ℃, distillate oil is discharged from the top of the reduced pressure distillation tower 7, the materials at the bottom of the reduced pressure distillation tower 7 enter a heating furnace 3 through a pipeline through a heavy oil pump 8 for short-time thermal conversion, the retention time is 80 seconds, and the temperature of the pipeline at the outlet of the heating furnace is 460 ℃. And then enters an asphalt granulator 12 for granulation to obtain an intermediate phase asphalt product. The operating conditions are listed in Table 2 and the product properties are listed in Table 3.
Comparative example 1
The process of comparative example 1 is shown in FIG. 2, which illustrates the case where the polymerization temperature of the polymerization vessel is 440 ℃ and the polymerization time is 8 hours, but the short-time thermal conversion treatment and the asphalt granulation treatment are not performed.
The heavy oil raw material stored in the raw material tank 1 is conveyed by a heavy oil pump 2 and enters a heating furnace 3 through a pipeline, and the temperature of the heated material at the outlet of the heating furnace is 480 ℃. The materials enter a polymerization reaction kettle 4 for reaction, the reaction temperature is 440 ℃, and the reaction is stopped by reducing the temperature of the polymerization kettle after the polymerization time is 8 hours. The product formed enters the flash tank 5 through a line, and the flash tank 5 is operated at 350 ℃. And discharging the small-molecular hydrocarbons generated by cracking from the top of the flash tank 5, and feeding the materials at the bottom of the flash tank 5 into a reduced-pressure distillation tower 7 through a heavy oil pump 6. And carrying out reduced pressure distillation on the materials in a reduced pressure distillation tower 7, wherein the reduced pressure cutting temperature is 525 ℃, distillate oil is discharged from the top of the reduced pressure distillation tower 7, and the materials at the bottom of the reduced pressure distillation tower 7 are the mesophase pitch product.
The operating conditions are listed in Table 2 and the product properties are listed in Table 3.
TABLE 1 heavy feed oil Properties
TABLE 2 operating conditions
| Example 1 | Example 2 | Example 3 | Comparative example 1 | |
| Polymerization temperature, DEG C | 440 | 450 | 460 | 440 |
| Polymerization time, |
8 | 4 | 4 | 8 |
TABLE 3 mesophase pitch Properties
| Example 1 | Example 2 | Example 3 | Comparative example 1 | |
| Softening point, DEG C | 316 | 312 | 340 | 296 |
| Mesophase content of% | 92 | 90 | 90 | 78 |
| Mesophase morphology | Stream domain | Stream domain | Stream domain | Uniform sphere |
| Carbon content, wt% | 94.14 | 94.47 | 94.79 | 94.20 |
| Hydrogen content, wt.% | 5.22 | 4.78 | 4.82 | 5.31 |
| Sulfur content, wt.% | 0.23 | 0.15 | 0.21 | 0.20 |
| Nitrogen content, wt% | 0.22 | 0.38 | 0.14 | 0.25 |
As can be seen from table 3, the mesophase pitch prepared by the method for preparing mesophase pitch provided by the present invention is mesophase pitch with a mesophase content of more than 90% and a mesophase morphology of streamline domains.
Claims (12)
1. A method for preparing mesophase pitch, characterized by, send the heavy oil raw materials into the polymerization reactor after heating through the heating furnace, after reacting for 3-24 hours at the temperature of 400-480 duC, enter the flash tank and isolate the distillate oil with boiling point less than 350 duC, the other supplies are sent into the vacuum distillation column, isolate the distillate oil with boiling point less than 480-550 duC in the vacuum distillation column; and (3) feeding the material at the bottom of the reduced pressure distillation tower into a heating furnace for thermal conversion, and finally feeding the material into an asphalt granulator to contact with nitrogen for spray granulation to obtain mesophase asphalt.
2. The method for preparing mesophase pitch according to claim 1, wherein said heavy oil feedstock is a heavy oil product rich in polycyclic aromatic hydrocarbons, the content of polycyclic aromatic hydrocarbons being greater than 80wt%;
preferably, the heavy oil raw material is selected from one or a mixture of several of catalytic oil slurry, furfural extract oil, coal chemical by-product low-temperature, medium-temperature and high-temperature coal tar;
preferably, the distillation range of the heavy oil feedstock is in the range of 350-500 ℃;
preferably, the distillation range of the heavy oil feedstock is the fraction at 350-400 ℃,400-450 ℃,400-460 ℃,450-500 ℃,400-430 ℃,430-460 ℃ or 460-490 ℃.
3. The method for preparing mesophase pitch according to claim 2, wherein the heavy oil feedstock is first contacted with a hydrotreating catalyst in a hydrogenation reactor to carry out hydrogenation reaction to remove sulfur and nitrogen impurities;
preferably, the heavy oil feedstock after hydrogenation has a sulfur content of no greater than 0.25wt% and a nitrogen content of no greater than 0.25wt%.
4. A process for preparing mesophase pitch according to claim 1, 2 or 3 wherein the heavy oil feedstock is subjected to a solids removal treatment prior to introduction into the furnace, the solids content of the heavy oil feedstock after the solids removal treatment being less than 20 μ g/g.
5. A process for the preparation of mesophase pitch according to claim 1, 2 or 3, wherein the heavy oil feedstock is heated in a furnace, the temperature of the feedstock at the furnace exit being in the range of 450 to 500 ℃;
preferably, the temperature of the material at the outlet of the heating furnace is 470-480 ℃.
6. A process for preparing mesophase pitch according to claim 1, 2 or 3, wherein the batch reaction is carried out in a polymerization reactor for a period of 3 to 11 hours at a temperature of 440 to 460 ℃.
7. The process for producing mesophase pitch according to claim 1, 2 or 3, wherein the temperature at the top of the vacuum distillation column is from 270 to 290 ℃ and the operating pressure is not more than 10mmHg.
8. A process for producing mesophase pitch according to claim 7, characterized in that distillate oil having a boiling point of less than 520 to 535 ℃ is separated in a vacuum distillation column.
9. The process for producing mesophase pitch according to claim 1, wherein said bottom material of the vacuum distillation tower has a residence time of 120 to 300 seconds in the heating furnace and an outlet temperature of 460 to 480 ℃.
10. The method for preparing mesophase pitch according to claim 1, wherein the temperature of introducing nitrogen gas into the pitch granulator is normal temperature, and the operating pressure is 0.2 to 0.4MPa.
11. A device for preparing mesophase pitch is characterized in that a raw material feeding pipeline is communicated with a polymerization reaction kettle, a flash tank and a reduced pressure distillation tower through a heating furnace, and a tower bottom outlet of the reduced pressure distillation tower is communicated with a pitch granulator through the heating furnace; wherein, two material pipelines are arranged in the heating furnace, one is a raw material feeding pipeline, and the other is a pressure reduction tower bottom discharging pipeline; the polymerization reactor is internally provided with an electric heating rod, and the outside of the polymerization reactor is provided with an electric heating sleeve; the asphalt granulator is provided with a nitrogen inlet and a nitrogen outlet.
12. The apparatus for producing mesophase pitch according to claim 11, wherein heavy oil pumps are provided in the feed line, the connecting line between the flash tank and the vacuum distillation column, and the connecting line between the bottom of the vacuum distillation column and the heating furnace.
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