CN114410331B - Method for preparing spinnable mesophase pitch with low cost - Google Patents
Method for preparing spinnable mesophase pitch with low cost Download PDFInfo
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- 239000011302 mesophase pitch Substances 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 36
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 90
- 238000006243 chemical reaction Methods 0.000 claims abstract description 55
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 45
- 239000000047 product Substances 0.000 claims abstract description 30
- 238000000926 separation method Methods 0.000 claims abstract description 27
- 238000004519 manufacturing process Methods 0.000 claims abstract description 25
- 239000010426 asphalt Substances 0.000 claims abstract description 19
- 239000013067 intermediate product Substances 0.000 claims abstract description 14
- 238000002156 mixing Methods 0.000 claims abstract description 13
- 238000003860 storage Methods 0.000 claims abstract description 9
- 125000004122 cyclic group Chemical group 0.000 claims abstract description 8
- 239000002994 raw material Substances 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 16
- 238000001704 evaporation Methods 0.000 claims description 11
- 230000008020 evaporation Effects 0.000 claims description 11
- 239000003638 chemical reducing agent Substances 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 8
- 230000014759 maintenance of location Effects 0.000 claims description 8
- 238000002360 preparation method Methods 0.000 claims description 8
- 239000012528 membrane Substances 0.000 claims description 7
- 239000011269 tar Substances 0.000 claims description 7
- MWPLVEDNUUSJAV-UHFFFAOYSA-N anthracene Chemical compound C1=CC=CC2=CC3=CC=CC=C3C=C21 MWPLVEDNUUSJAV-UHFFFAOYSA-N 0.000 claims description 6
- 238000004523 catalytic cracking Methods 0.000 claims description 4
- 238000007790 scraping Methods 0.000 claims description 4
- 230000005484 gravity Effects 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims description 3
- 239000011280 coal tar Substances 0.000 claims description 2
- 229930195733 hydrocarbon Natural products 0.000 claims description 2
- 150000002430 hydrocarbons Chemical class 0.000 claims description 2
- 150000003839 salts Chemical class 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- 239000003921 oil Substances 0.000 abstract description 27
- 150000004945 aromatic hydrocarbons Chemical class 0.000 abstract description 6
- 239000000295 fuel oil Substances 0.000 abstract description 4
- 239000000203 mixture Substances 0.000 abstract description 2
- 229920000049 Carbon (fiber) Polymers 0.000 description 9
- 239000004917 carbon fiber Substances 0.000 description 9
- 230000035484 reaction time Effects 0.000 description 9
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 8
- 238000006068 polycondensation reaction Methods 0.000 description 5
- 230000003197 catalytic effect Effects 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000004821 distillation Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011295 pitch Substances 0.000 description 3
- 238000003763 carbonization Methods 0.000 description 2
- 238000006482 condensation reaction Methods 0.000 description 2
- 238000002074 melt spinning Methods 0.000 description 2
- 125000005575 polycyclic aromatic hydrocarbon group Chemical group 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 238000009987 spinning Methods 0.000 description 2
- 238000004227 thermal cracking Methods 0.000 description 2
- 238000005292 vacuum distillation Methods 0.000 description 2
- 125000003118 aryl group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005087 graphitization Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10C—WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID
- C10C1/00—Working-up tar
- C10C1/04—Working-up tar by distillation
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Working-Up Tar And Pitch (AREA)
Abstract
The invention relates to a method for preparing spinnable mesophase pitch at low cost. Mixing preheated fresh raw oil with nitrogen by taking heavy oil rich in aromatic hydrocarbon as raw oil, entering from the upper end of a temperature-changing and diameter-changing tubular reactor and rapidly passing through the reactor to obtain an asphalt-like intermediate product with a softening point of 40-160 ℃; and then the mixture enters a hot low-pressure separation tank, nitrogen and part of light components are separated from the upper part of the hot low-pressure separation tank, a bottom product enters a wiped film evaporator to remove and recover the light components, and heavy components obtained from the bottom of the evaporator enter an intermediate phase storage tank, so that high-quality spinnable intermediate phase asphalt is obtained. And nitrogen recovered by the heat low-pressure separation tank and the wiped film evaporator and fractions of light components at a temperature of more than or equal to 200 ℃ are mixed and preheated, and then enter the reactor from the middle reducing part of the reactor for circular reaction, so that the conversion rate of producing the mesophase pitch by using the raw oil is improved. The invention can produce high-quality mesophase pitch in a large scale at low cost by a continuous rapid and cyclic reaction mode and a production system.
Description
Technical Field
The invention relates to a method for producing high-quality spinnable mesophase pitch in a large scale by taking heavy oil rich in aromatic hydrocarbon as a raw material through a continuous rapid and cyclic reaction mode and a production system with low cost, belonging to the technical field of preparation of high-quality carbon fibers of high-grade carbon materials.
Background
The preparation process of the mesophase pitch-based carbon fiber mainly comprises the steps of using aromatic hydrocarbon-rich heavy oil as a raw material, forming a mesophase pitch precursor through polycondensation, and carrying out a series of processes such as melt spinning, pre-oxidation, carbonization/graphitization and the like to obtain the high-performance mesophase pitch-based carbon fiber. Compared with the performance of polyacrylonitrile-based carbon fiber, the most outstanding performance of the mesophase pitch-based carbon fiber is ultrahigh modulus, ultrahigh heat conduction and electric conductivity, low thermal expansion coefficient (the thermal expansion coefficient can be realized to be a negative value), and the like, so the mesophase pitch-based carbon fiber is more suitable for being applied to important parts such as satellite antennas, rocket nozzles, aircraft high-rigidity panels, aircraft electromagnetic shielding protection systems, and the like, can also be applied to robot arms, large industrial rollers, pressure containers, electronic product thermal management, LED thermal management, and the like, is an important strategic material for developing high-end equipment manufacturing industry, and still belongs to high-end products at present. However, the mesophase pitch-based carbon fiber has a great potential for cost reduction because the mesophase pitch-based carbon fiber is produced using inexpensive heavy aromatic hydrocarbons as a raw material. The large-scale and low-cost preparation of the mesophase pitch can greatly promote the pitch-based carbon fiber to be widely applied to the fields of rail transit, automobile lightweight, IT manufacturing robots, building reinforcement, sports, civil use and the like.
The traditional mesophase pitch preparation adopts a high-pressure reaction kettle, a series of operations such as heating, constant temperature, cooling, kettle discharging and the like are needed in the production process, and the intermittent production efficiency is very low. Although some researchers prepare a plurality of reaction kettles in a multi-stage series connection mode, the whole process belongs to an intermittent production process, and the method is long in production time, high in labor intensity, low in yield, high in production cost and poor in stability among batches. In addition, the reaction time for preparing the mesophase pitch in the traditional method is mostly between 6 and 18 hours, and is even longer, so that the large-scale production capacity is greatly influenced. Meanwhile, non-intermediate phase products (often light aromatic hydrocarbons which can be further converted into intermediate phase molecules) in the products are removed by adopting traditional processes such as high-pressure polymerization, vacuum distillation and the like, and the yield of the obtained spinnable intermediate phase pitch is mostly less than or equal to 40 percent, so that the utilization conversion rate of raw materials is low. Chinese patent CN207996650U replaces the traditional high pressure-vacuum reactor device with a tubular reactor and two parallel vacuum reactors, the temperature of the reactor is 450 deg.c, although the patent specification does not give out the reaction time, the reaction time can still be reasonably predicted to be several hours, which also greatly affects the production efficiency. And also does not involve a process flow for further recycling of light components. Chinese patent CN113773871A discloses a continuous cyclic polymerization distillation reaction system for preparing mesophase pitch, which adopts a pipeline type continuous line production mode and a cyclic flow reaction mode, controls the reaction time by adjusting the cycle times so as to produce different mesophase pitches, and particularly improves the devolatilization effect by repeatedly and circularly flowing materials under vacuum in a vacuum distillation devolatilization stage. However, the problem of low conversion utilization of the feedstock oil is not solved. Therefore, in order to develop a method and a reaction system for preparing spinnable mesophase pitch with low cost and engineering, three limiting factors, namely, the reactor cannot be used for continuous production, the reaction time is long, the utilization conversion rate of raw oil is low, and the like, need to be developed, so that large-scale engineering continuous preparation can be realized, the production cost is reduced, the production efficiency is improved, and high-performance and high-purity mesophase pitch for spinning is produced.
Disclosure of Invention
The invention mainly solves the problem of how to produce the high-quality mesophase pitch for spinning in a large scale with low cost. Therefore, aromatic hydrocarbon-rich heavy oil is used as raw oil, preheated fresh raw oil and nitrogen are mixed, enter from the upper end of the temperature-changing and diameter-changing tubular reactor and quickly pass through the reactor, and an asphalt-shaped intermediate product with the softening point of 40-160 ℃ is obtained; and then the mixture enters a hot low-pressure separation tank, nitrogen and part of light components are separated and recovered, a product at the bottom of the tank enters a wiped film evaporator to further remove and recover the light components, and heavy components obtained at the bottom of the evaporator enter an intermediate phase storage tank, so that high-quality spinnable intermediate phase asphalt is obtained. And nitrogen and light components recovered by the thermal low-pressure separation tank and the wiped film evaporator are mixed and preheated, and then enter the reactor from the middle reducing part of the reactor for cyclic reaction, so that the conversion utilization rate of raw oil is improved. The invention can produce high-quality mesophase pitch in a large scale at low cost through a continuous rapid and cyclic reaction mode and a production system.
In order to realize the purpose, the method for preparing the spinnable mesophase pitch at low cost takes one or more of catalytic cracking tar, FCC slurry clarified oil, tetra-linear reduced fraction, deasphalted oil of naphthenic vacuum residue, QI-removed refined coal tar and anthracene oil as raw materials, and specifically comprises the following process flows:
(1) Preheating fresh raw oil and nitrogen, continuously feeding the preheated fresh raw oil and nitrogen into a reactor from the upper part of a variable-temperature variable-diameter tubular reactor, and standing the fresh raw oil for reaction for 1-30 min to obtain an asphalt-like intermediate product with a softening point of 40-160 ℃ at the bottom of the reactor;
(2) The asphaltic intermediate product enters a thermal low-temperature separation tank with the constant temperature of 350-430 ℃ and the pressure of 0.01-0.1 MPa, nitrogen and light components are separated from the upper part of the thermal low-temperature separation tank, and a bottom product enters a wiped film evaporator;
(3) The constant temperature of the wiped film evaporator is 350-430 ℃, the pressure is 0.1-5.0 KPa, the materials are efficiently and quickly removed of light components after entering the wiped film evaporator and are separated from the upper part of the evaporator, heavy components obtained at the bottom of the evaporator enter an intermediate phase storage tank, and thus a spinnable intermediate phase asphalt product with the intermediate phase content of more than or equal to 90% and the softening point of 220-350 ℃ is obtained; the residence time in the wiped film evaporator is 1 to 60s;
(4) Mixing nitrogen and light components separated from the upper part of the thermal low-molecular tank and light components separated from the upper part of the wiped film evaporator, distilling and separating fractions at a temperature of more than or equal to 200 ℃, separating nitrogen from gaseous hydrocarbons in a membrane separation mode to obtain recycled light components, mixing and preheating the fractions at a temperature of more than or equal to 200 ℃ and the nitrogen according to a mass ratio of 0.25-10, and entering a reactor from a middle variable diameter part of the variable-temperature variable-diameter tubular reactor for circular reaction to improve the conversion rate of producing mesophase pitch from raw oil.
In the invention, the temperature-changing and diameter-changing tubular reactor has an upper section and a lower section, the length ratio of the upper section to the lower section is 1-2, the pipe diameter of the upper section is larger than that of the lower section, the pipe diameter ratio of the upper section to the lower section is at least 1.5 and is not more than 5, and the length-diameter ratio of the upper section to the lower section is at least 50; as a specific scheme, the inner diameter of the upper section pipe diameter of the reactor is 20-50 mm, and the inner diameter of the lower section pipe diameter is 10-30 mm; the total length of the reactor is 5-20 m; the upper section and the lower section are rigidly connected (welded) or integrally formed.
In the invention, the temperature of the upper section of the variable-temperature variable-diameter tubular reactor is set to be 550-700 ℃, and the temperature of the lower section is set to be 500-550 ℃; fresh raw oil continuously enters the reactor from the upper part of the temperature-changing and diameter-changing tubular reactor, stays for reaction for 1min to 30min, remixed light components and nitrogen are mixed and preheated according to the mass ratio of 0.25 to 10, enter the reactor from the diameter-changing part of the temperature-changing and diameter-changing tubular reactor for circulation reaction, and stay for reaction for 5s to 20min.
In the invention, the wiped film evaporator adopts a vertical structure and consists of an upper driving part and a lower evaporation and concentration part, wherein the driving part consists of a motor and a speed reducer, and the speed reducer is a gear speed reducer or a belt wheel speed reducer; the evaporation concentration part consists of a distributor, a gas-liquid separator, an evaporation cylinder, a cylinder jacket and a rotary scraper; the shaft seals at the upper part and the lower part adopt double-sided mechanical seal to ensure the sealing property of the equipment; the scraping plate adopts a fixed type and a rotor type. The preheated feed liquid is added from the upper part of the wiped film evaporator along the tangential direction and is distributed on the heating wall surface of the evaporation cylinder body through the distributing device. Due to the gravity, the centrifugal force and the scraping action of the rotating scraper, the feed liquid forms a uniform downward-rotating film on the inner wall of the evaporation section cylinder, the temperature of the cylinder wall is regulated by heating media such as fused salt or heat conducting oil in the cylinder jacket in the process, the material is kept at a set temperature through heat transfer of the cylinder wall, surface substances of the material are rapidly evaporated, the concentrated solution is discharged at the bottom, and the evaporated secondary steam is recycled to an external low-pressure separation tank through an upper outlet.
According to the difference of reaction severity required by forming a mesophase structure between raw oil molecules and fractions at the temperature of more than or equal to 200 ℃, the method adopts a variable-temperature variable-diameter tubular reactor to carry out segmented reaction on the raw oil molecules and the fractions, namely the fresh raw oil molecules have smaller size, more and longer side chains and larger difference with the mesophase molecular structure, and need harsh reaction conditions for conversion; the recycled light component molecules are obtained through thermal conversion reaction, so that the side chains are shorter, the molecular size is closer to that of the mesophase molecules, and the relatively mild reaction conditions are adopted, so that the conversion of the recycled light component molecules into the mesophase molecules is promoted, and the phenomenon that the softening point of the mesophase pitch is sharply increased or even the melt spinning cannot be performed due to the initiation of 'excessive polycondensation' is avoided. On the other hand, the conversion of raw oil molecules into planar polycyclic aromatic hydrocarbon macromolecules requires a thermal cracking reaction in which side chains are broken to initiate radicals, followed by a condensation reaction to increase the aromatic ring size.
Based on the above, in the step (1), the temperature-variable and diameter-variable tubular reactor is adopted to realize that the fresh raw material and the recycled raw material can be converted under the appropriate thermal polycondensation reaction condition, so that the raw material conversion rate is improved, and the quality of the mesophase pitch is ensured. Specifically, the upper temperature of the reactor is higher than the conventional temperature range (400-500 ℃) for preparing mesophase pitch and is 550-700 ℃, so that the cracking reaction is promoted, the reaction rate is accelerated, and a foundation is laid for improving the production efficiency; the inner diameter of the pipe diameter at the upper part of the reactor is 20-50 mm, and the diameter range ensures that the reaction process has good mass and heat transfer effects while ensuring the raw material treatment capacity. The lower part of the reactor adopts a relatively mild reaction temperature of 500-550 ℃, but is still higher than the conventional temperature for preparing the mesophase pitch, and the lower reaction temperature is favorable for further condensation reaction of thermal cracking product molecules and promotes the formation of polycyclic aromatic hydrocarbon planar molecules; the inner diameter of the lower pipe diameter is also smaller than that of the upper pipe diameter and is 10-30 mm, the more the material flow rate is higher, the greater the turbulence degree of the material is, the shorter the retention time is and the better the mass transfer effect is when the recycle components and the upper-section products of the reactor are in smaller pipe diameters, the more the conversion to mesophase molecules is promoted, and simultaneously, the occurrence of excessive carbonization reaction, particularly the occurrence of coking on the pipe wall can be effectively avoided. The total length of the reactor can be designed to be 5-20 m, the length of the part with larger pipe diameter at the upper part accounts for 1/2-2/3 of the total length, the fresh materials are kept for reaction for 1-30 min, the fraction with the temperature of more than or equal to 200 ℃ in the light component is kept for 5-20 min, and the reaction time is greatly reduced compared with the reaction time (several hours to dozens of hours) of the conventional process. In addition, different raw materials realize thermal polycondensation decoupling in the variable-temperature variable-diameter reactor, and further ensure that spinnable mesophase pitch products are continuously prepared all the time, so that an organic integral system is formed with the subsequent process flow of recovering light components. In conclusion, the reaction time is greatly reduced, the utilization rate of raw materials is improved, the reaction processes are integrally matched with each other, and the preparation of high-quality mesophase pitch with low cost and high production efficiency is guaranteed.
In the steps (2) and (3) of the invention, continuous two-stage distillation recovery separation operation is adopted. The temperature of the hot low-pressure separating tank adopted in the step (2) is 350-430 ℃, the pressure is 0.01-0.1 MPa, and after nitrogen and part of light components are primarily separated, the material can be effectively prevented from generating steam entrainment due to large-amount volatilization under the high vacuum condition of the wiped film evaporator. And (4) after the material enters the wiped film evaporator, the material is continuously and uniformly distributed on a vertical heating surface of the cylinder through the distributor, when the material descends by means of gravity, a very thin turbulent liquid film is forcibly formed on the heating surface by the rotating wiped film device, the heated and evaporated light component steam enters the external condenser from an upper outlet for condensation, and the heavy component which is not evaporated is discharged from the bottom of the wiped film evaporator. The whole process time is usually several seconds to dozens of seconds, so that the influence on the product quality caused by decomposition of the material due to long-time heating is effectively avoided, and the evaporation efficiency is improved.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the invention, by developing a rapid polycondensation reaction mode in a high-temperature tubular reaction and matching with efficient and rapid light component removal operation, the production efficiency is greatly improved, and the reaction time is reduced;
(2) The technical strategy adopted in the invention has no strict requirements on the properties of the raw materials, and the temperature-variable diameter-variable tubular reactor is adopted to couple the light component for 'recycling', so that the problem of low conversion utilization rate of the raw materials is solved while the preparation of the high-quality spinnable mesophase pitch is ensured.
(3) The invention can produce high-quality mesophase pitch in a large scale at low cost by a continuous rapid and cyclic reaction mode and a production system.
Drawings
FIG. 1 is a process flow diagram of a low cost method for preparing a spinnable mesophase pitch according to the present invention, wherein: 1-preheating a furnace; 2-temperature-changing and diameter-changing tubular reactor; 3-hot low-pressure separation tank; 4-wiped film evaporator; 5-cooling and low-temperature separating tank; 6-cooling and low-pressure separating tank; 7-a membrane separator; 8-a distillation column; 9-intermediate phase asphalt product storage tank.
Detailed Description
The method of producing a spinnable mesophase pitch at low cost according to the present invention will be further described with reference to the following examples.
Example 1:
the catalytic cracking tar is used as a raw material, the total length of a vertical variable-temperature variable-diameter tubular reactor is 5m, the reactor consists of an upper section with the pipe diameter (inner diameter) of 20mm and the pipe length of 2.5m and a lower section with the pipe diameter (inner diameter) of 10mm and the pipe length of 2.5m, wherein the temperature of the upper section is set to be 550 ℃, and the temperature of the lower section is set to be 500 ℃;
the embodiment provides a method for preparing spinnable mesophase pitch at low cost, which comprises the following specific process flows:
mixing catalytic cracking tar and nitrogen according to the mass ratio of 9.0, preheating to 300 ℃, rapidly heating to 550 ℃ near the inlet of the reactor, and then entering the temperature-variable reducing tubular reactor from the upper part of the reactor for reaction, wherein the residence time in the reactor is 30min totally; in addition, distilling and membrane separating the nitrogen and light components separated in the subsequent process (mainly from the upper parts of the thermal low-pressure separation tank and the wiped-film evaporator) to obtain a fraction and nitrogen with the temperature of more than or equal to 200 ℃, mixing and preheating the fraction and the nitrogen according to the mass ratio of 9.0 to 320 ℃, quickly heating the fraction and the nitrogen to 500 ℃ near a middle variable-diameter inlet of the reactor, and then entering the reactor for staying and reacting for 10min; obtaining an asphalt-like intermediate product with a softening point of 40 ℃ at the bottom of the reactor;
immediately feeding the asphaltic intermediate product into a thermal low-temperature separation tank with the constant temperature of 350 ℃ and the pressure of 0.01MPa, separating nitrogen and part of light components from the upper part of the thermal low-temperature separation tank, and feeding the bottom product into a wiped film evaporator;
setting the constant temperature of the wiped film evaporator to be 350 ℃, the pressure to be 0.1KPa and the retention time to be 5s, and enabling the intermediate phase asphalt product to flow into a product storage tank at the bottom of the wiped film reactor, so that a spinnable intermediate phase asphalt product with 90% of intermediate phase content and 250 ℃ of softening point is obtained, wherein the conversion utilization rate of the intermediate phase asphalt produced by raw oil can reach 80%.
Example 2:
the method is characterized in that FCC slurry clarified oil is used as a raw material, the total length of a vertical temperature-changing and diameter-changing tubular reactor is 10m, the reactor consists of an upper section with the pipe diameter (inner diameter) of 30mm and the pipe length of 7.0m and a lower section with the pipe diameter (inner diameter) of 15mm and the pipe length of 3m, wherein the temperature of the upper section is set to be 600 ℃, and the temperature of the lower section is set to be 520 ℃.
The embodiment provides a method for preparing spinnable mesophase pitch at low cost, which comprises the following specific process flows:
mixing and preheating catalytic tar and nitrogen according to a mass ratio of 7 to 300 ℃, rapidly heating to 600 ℃ near an inlet of a reactor, and then entering the reactor from the upper part of the reactor for reaction, wherein the retention time in the reactor is 10min in total; in addition, distilling and membrane separating nitrogen and light components separated in the subsequent process (mainly from the upper parts of a thermal low-pressure separation tank and a wiped-film evaporator) to obtain fractions and nitrogen with the temperature of more than or equal to 200 ℃, mixing and preheating the fractions and the nitrogen according to the mass ratio of the fractions and the nitrogen of 7.0 to 320 ℃, quickly heating the fractions and the nitrogen to 520 ℃ near a middle variable-diameter inlet of the reactor, and immediately entering the reactor for staying and reacting for 5min; the bottom of the reactor can obtain an asphalt intermediate product with the softening point of 70 ℃;
immediately feeding the asphaltic intermediate product into a thermal low-pressure separation tank with the constant temperature of 380 ℃ and the pressure of 0.05MPa, separating nitrogen and part of light components from the upper part of the thermal low-pressure separation tank, and feeding the bottom product into a wiped film evaporator;
setting the constant temperature of a wiped film evaporator to be 380 ℃, the pressure to be 0.5KPa, the retention time to be 7s, and enabling the intermediate phase asphalt product to flow into a product storage tank at the bottom of the wiped film reactor, so that a spinnable intermediate phase asphalt product with the intermediate phase content of 95% and the softening point of 240 ℃ is obtained, and the conversion utilization rate of the intermediate phase asphalt produced by raw oil can reach 75%.
Example 3:
the vertical temperature-changing and diameter-changing tubular reactor is used as a raw material, the total length of the vertical temperature-changing and diameter-changing tubular reactor is 13m, the vertical temperature-changing and diameter-changing tubular reactor consists of an upper section with the pipe diameter (inner diameter) of 35mm and the pipe length of 8m and a lower section with the pipe diameter (inner diameter) of 17mm and the pipe length of 5m, wherein the temperature of the upper section is set to be 630 ℃, and the temperature of the lower section is set to be 530 ℃.
The embodiment provides a method for preparing spinnable mesophase pitch at low cost, which comprises the following specific process flows:
mixing and preheating catalytic tar and nitrogen according to the mass ratio of 2.0 to 300 ℃, rapidly heating to 630 ℃ near the inlet of the reactor, and then entering the reactor from the upper part of the reactor for reaction, wherein the residence time in the reactor is 5min totally; in addition, distilling and membrane separating the nitrogen and light components separated in the subsequent process (mainly from the upper parts of the thermal low-pressure separation tank and the wiped-film evaporator) to obtain a fraction and nitrogen with the temperature of more than or equal to 200 ℃, mixing and preheating the fraction and the nitrogen according to the mass ratio of 2.0 to 320 ℃, quickly heating the fraction and the nitrogen to 530 ℃ near a middle variable-diameter inlet of the reactor, and then entering the reactor for staying and reacting for 2min; an asphalt intermediate product with a softening point of 120 ℃ can be obtained at the bottom of the reactor;
the asphaltic intermediate product immediately enters a thermal low-temperature separation tank with the constant temperature of 400 ℃ and the pressure of 0.06MPa, nitrogen and partial light components are separated from the upper part of the thermal low-temperature separation tank, and a bottom product enters a wiped film evaporator;
setting the constant temperature of the wiped film evaporator at 400 ℃, the pressure at 0.6KPa and the retention time at 8s, and allowing the intermediate phase asphalt product to flow into a product storage tank at the bottom of the wiped film reactor, so as to obtain a spinnable intermediate phase asphalt product with the intermediate phase content of 100% and the softening point of 260 ℃, wherein the conversion utilization rate of the intermediate phase asphalt produced by raw oil can reach 72%.
Example 4:
the anthracene oil is used as a raw material, the total length of a vertical temperature-changing and diameter-changing tubular reactor is 20m, and the vertical temperature-changing and diameter-changing tubular reactor consists of an upper section with the pipe diameter (inner diameter) of 45mm and the pipe length of 13m and a lower section with the pipe diameter (inner diameter) of 25mm and the pipe length of 7m, wherein the temperature of the upper section is set to be 680 ℃, and the temperature of the lower section is set to be 540 ℃.
The embodiment provides a method for preparing spinnable mesophase pitch at low cost, which comprises the following specific process flows:
mixing and preheating catalytic tar and nitrogen according to the mass ratio of 0.25 to 300 ℃, rapidly heating to 680 ℃ near the inlet of the reactor, and then entering the reactor from the upper part of the reactor for reaction, wherein the retention time in the reactor is 1min in total; in addition, distilling and membrane separating the nitrogen and light components separated in the subsequent process (mainly from the upper parts of the heat low-pressure separation tank and the wiped-film evaporator) to obtain fractions and nitrogen with the temperature of more than or equal to 200 ℃, mixing and preheating the fractions and the nitrogen according to the mass ratio of 0.25 to 320 ℃, quickly heating the fractions and the nitrogen to 540 ℃ near a middle variable-diameter inlet of the reactor, and then entering the reactor for staying for reaction for 5 seconds; the bottom of the reactor can obtain an asphalt-shaped intermediate product with the softening point of 160 ℃;
immediately feeding the asphaltic intermediate product into a thermal low-temperature separation tank with the constant temperature of 430 ℃ and the pressure of 0.1MPa, separating nitrogen and part of light components from the upper part of the thermal low-temperature separation tank, and feeding the bottom product into a wiped film evaporator;
setting the constant temperature of the wiped film evaporator to be 430 ℃, the pressure to be 5.0KPa and the retention time to be 3s, and enabling the intermediate phase asphalt product to flow into a product storage tank at the bottom of the wiped film reactor, so that a spinnable intermediate phase asphalt product with the intermediate phase content of 100% and the softening point of 280 ℃ is obtained, and the conversion utilization rate of the intermediate phase asphalt produced by raw oil can reach 70%.
Claims (8)
1. A method for preparing spinnable mesophase pitch at low cost takes one or more of catalytic cracking tar, FCC slurry clarified oil, four-linear distillate, deasphalted oil of naphthenic vacuum residue, refined coal tar subjected to QI removal and anthracene oil as raw material oil, and is characterized by comprising the following steps:
(1) Preheating fresh raw oil and nitrogen, continuously feeding the preheated fresh raw oil and nitrogen into a reactor from the upper part of a variable-temperature variable-diameter tubular reactor, and keeping the fresh raw oil for reacting for 1-30 min to obtain an asphalt-like intermediate product with a softening point of 40-160 ℃ at the bottom of the reactor; the temperature-changing and diameter-changing tubular reactor has an upper section and a lower section, the length ratio of the upper section to the lower section is 1-2, the pipe diameter of the upper section is larger than that of the lower section, the temperature of the upper section of the temperature-changing and diameter-changing tubular reactor is 550-700 ℃, and the temperature of the lower section is 500-550 ℃;
(2) The asphaltic intermediate product enters a hot low-pressure separation tank, nitrogen and light components are separated from the upper part of the hot low-pressure separation tank, and a bottom product enters a wiped film evaporator; the constant temperature of the thermal low-pressure separating tank is 350-430 ℃, and the pressure is 0.01-0.1 MPa;
(3) The material enters a wiped film evaporator, then light components are efficiently and quickly removed and separated from the upper part of the wiped film evaporator, and heavy components obtained from the bottom of the wiped film evaporator enter an intermediate phase storage tank, so that a spinnable intermediate phase asphalt product with the intermediate phase content of not less than 90% and the softening point of 220-350 ℃ is obtained; the constant temperature of the wiped film evaporator is 350-430 ℃, the pressure is 0.1-5.0 KPa, and the retention time of the feed liquid is 1-60 s.
2. The process for low-cost preparation of spinnable mesophase pitch according to claim 1, wherein: mixing nitrogen and light components separated from the upper part of the thermal low-molecular tank and light components separated from the upper part of the wiped film evaporator, distilling and separating fractions at a temperature of more than or equal to 200 ℃, separating nitrogen from gaseous hydrocarbons in a membrane separation mode, mixing and preheating the fractions at a temperature of more than or equal to 200 ℃ and the nitrogen according to a mass ratio of 0.25-10, entering a reactor from a middle reducing part of the temperature-changing and diameter-changing tubular reactor for cyclic reaction, and staying for 5 s-20 min for reaction so as to improve the conversion rate of producing mesophase pitch from raw oil.
3. A low cost process for preparing a spinnable mesophase pitch according to claim 1 or 2, characterized in that: the temperature and the pipe diameter of the upper part of the temperature-changing and diameter-changing tubular reactor are larger than those of the lower part, the pipe diameter ratio of the upper section to the lower section is at least 1.5 and is not more than 5.
4. A low cost process for preparing a spinnable mesophase pitch according to claim 3, wherein: the inner diameter of the upper section pipe diameter of the reactor is 20-50 mm, and the inner diameter of the lower section pipe diameter is 10-30 mm; the total length of the reactor is 5-20 m, and the upper section and the lower section are rigidly connected or integrally formed.
5. A low cost process for preparing a spinnable mesophase pitch according to claim 1, wherein: the wiped film evaporator is of a vertical structure and consists of an upper driving part and a lower evaporation and concentration part, the driving part consists of a motor and a speed reducer, and the evaporation and concentration part consists of a distributor, a gas-liquid separator, an evaporation cylinder, a cylinder jacket and a rotary scraper; and the shaft seals at the upper part and the lower part adopt double-sided mechanical seal to ensure the tightness of the equipment.
6. A low cost process for preparing a spinnable mesophase pitch according to claim 5, wherein: the speed reducer is a gear speed reducer or a belt wheel speed reducer; the scraping plate adopts a fixed type and a rotor type.
7. A low cost process for preparing a spinnable mesophase pitch according to claim 5, wherein: the preheated feed liquid is added from the upper part of the wiped film evaporator along the tangential direction and is distributed on the heating wall surface of the evaporation cylinder through a distributor; due to the gravity, the centrifugal force and the scraping action of the rotating scraper, the feed liquid forms a uniform downward-rotating film on the inner wall of the evaporation section cylinder, the temperature of the cylinder wall is adjusted through a fused salt or a heat conducting oil heating medium in a cylinder jacket in the process, the material is kept at a set temperature through the heat conduction of the cylinder wall, surface substances of the material are quickly evaporated, the concentrated solution is discharged at the bottom, and the evaporated secondary steam is recycled to an external cold low-pressure separation tank through an upper outlet.
8. A low cost process for preparing a spinnable mesophase pitch according to claim 1, wherein: the conversion utilization rate of the mesophase pitch produced by the raw oil is at least 70 percent.
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| CN202210229316.2A CN114410331B (en) | 2022-03-09 | 2022-03-09 | Method for preparing spinnable mesophase pitch with low cost |
| PCT/CN2023/092544 WO2023169604A1 (en) | 2022-03-09 | 2023-05-06 | Low-cost method for preparing spinnable mesophase pitch |
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| CN202210229316.2A CN114410331B (en) | 2022-03-09 | 2022-03-09 | Method for preparing spinnable mesophase pitch with low cost |
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| CN114410331B (en) * | 2022-03-09 | 2022-10-25 | 中国石油大学(华东) | Method for preparing spinnable mesophase pitch with low cost |
| CN117983167B (en) * | 2024-04-03 | 2024-07-19 | 克拉玛依市先进能源技术创新有限公司 | System and method for preparing mesophase pitch and universal grade pitch |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008297656A (en) * | 2007-05-31 | 2008-12-11 | Teijin Ltd | Method for producing carbon fiber |
| CN103184062A (en) * | 2013-04-03 | 2013-07-03 | 天津大学 | Preparation method of high softening point spinning pitch |
| CN113680301A (en) * | 2021-07-23 | 2021-11-23 | 东华大学 | Method and device for preparing spinnable mesophase pitch |
| CN113817501A (en) * | 2021-09-20 | 2021-12-21 | 中海油天津化工研究设计院有限公司 | Combined process method for producing olefin, aromatic hydrocarbon and mesophase pitch-based carbon fiber from crude oil |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090321313A1 (en) * | 2008-06-30 | 2009-12-31 | Mezza Beckay J | Process for Determining Presence of Mesophase in Slurry Hydrocracking |
| CN114410331B (en) * | 2022-03-09 | 2022-10-25 | 中国石油大学(华东) | Method for preparing spinnable mesophase pitch with low cost |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008297656A (en) * | 2007-05-31 | 2008-12-11 | Teijin Ltd | Method for producing carbon fiber |
| CN103184062A (en) * | 2013-04-03 | 2013-07-03 | 天津大学 | Preparation method of high softening point spinning pitch |
| CN113680301A (en) * | 2021-07-23 | 2021-11-23 | 东华大学 | Method and device for preparing spinnable mesophase pitch |
| CN113817501A (en) * | 2021-09-20 | 2021-12-21 | 中海油天津化工研究设计院有限公司 | Combined process method for producing olefin, aromatic hydrocarbon and mesophase pitch-based carbon fiber from crude oil |
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| CN114410331A (en) | 2022-04-29 |
| WO2023169604A1 (en) | 2023-09-14 |
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