Continuous separation method of mesophase pitch

Abstract

The invention belongs to the technical field of mesophase pitch production, and particularly relates to a continuous separation method of mesophase pitch. According to the technical scheme, the continuous separation method of the mesophase pitch comprises the following steps: introducing a polymerization liquid in a molten state into a special cone centrifuge, and forcing light liquid to gather upwards and heavy liquid to gather downwards in a high-speed rotation process of a material under a specific taper, and the two kinds of pitch are separated by utilizing the density difference between the mesophase pitch and the isotropic pitch, so that the high-purity mesophase pitch is obtained. The method is simple to operate, the intermediate phase content of the product is stable, and the problem that cracking and coking are easy to generate in the intermediate phase pitch purification process is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of mesophase asphalt production, and in particular relates to a continuous separation method of mesophase asphalt. Background Art

[0002] Mesophase pitch is a precursor material for the preparation of high-performance asphalt-based carbon fibers, mesophase carbon microbeads, needle coke and other advanced carbon materials. High-performance carbon materials require that the mesophase pitch has the characteristics of high aromaticity, low ash content and narrow molecular weight distribution.

[0003] Most of the traditional methods for preparing mesophase pitch are two-step methods, that is, firstly, a polymer solution is obtained by thermal polycondensation or catalytic polymerization, and the polymer solution contains mesophase pitch and homogeneous pitch with a lower degree of polymerization, and then the homogeneous pitch is removed by negative pressure flash evaporation to obtain mesophase pitch. Due to the extremely high boiling point of homogeneous pitch, the flash evaporation temperature of this preparation method of mesophase pitch often has to reach 380-420°C, or even higher. At this temperature, the polymer solution is prone to cracking and coking, resulting in the formation of a large number of pores and secondary quinoline insolubles in the mesophase pitch, which greatly troubles the subsequent spinning process and has a serious impact on the production process of mesophase pitch-based carbon fibers and the stability of the mechanical properties of the products. It can be said that how to effectively separate the mesophase pitch from the homogeneous pitch in the polymer solution without causing the polymer solution to crack, coke, etc. is the core technical problem that plagues the preparation of mesophase pitch. Summary of the invention

[0004] The present invention mainly aims at the problems that the mesophase asphalt is prone to cracking and coking during the purification process, and the mesophase content of the product is unstable. It provides a continuous separation method for mesophase asphalt which is simple to operate, not prone to cracking and coking reactions, and has a stable mesophase content in the obtained product.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0006] The polymerization liquid (9) is introduced into the vertebral centrifuge (4) from the polymerization liquid buffer tank (1), and the polymerization liquid feed rate is controlled by the flow regulating valve (3) to be 5-20KG / h, the polymerization liquid feed temperature is 200-350°C, and the centrifuge inlet pressure is 0.05-0.5Mpa; the isotropic asphalt is produced from the upper outlet of the centrifuge, and after passing the test, it enters the isotropic asphalt tank (8); the mesophase asphalt is produced from the lower outlet of the centrifuge, and after passing the test, it enters the mesophase asphalt tank (7).

[0007] The content of mesophase asphalt in the polymerization liquid is 60-70%.

[0008] The rotation speed of the vertebral centrifuge is 0-3000r / min, the motor speed can be adjusted by variable frequency, and the maximum operating temperature of the vertebral centrifuge is 350℃.

[0009] The polymerization liquid delivery pipeline is provided with a flow regulating valve (3) to adjust the feeding rate of the polymerization liquid; the polymerization liquid delivery pipeline is provided with a sampling port (2) to regularly sample and monitor the change of the intermediate phase asphalt content in the polymerization liquid; the polymerization liquid delivery pipeline and valves are both jacketed for heating, the heating temperature is 200-350°C, and the heat medium can be but is not limited to high-pressure steam and high-temperature heat transfer oil.

[0010] The delivery pipelines from the vertebral centrifuge to the isotropic asphalt tank and the mesophase asphalt tank are respectively provided with quality monitoring ports (6) and (5). The centrifugal temperature and the centrifuge speed are adjusted in time according to the monitoring data to ensure the product quality. The delivery pipeline is heated by a jacket at a temperature of 250 to 350°C. The heat medium can be, but is not limited to, high-pressure steam, high-temperature heat transfer oil, or molten salt.

[0011] The purity of the produced mesophase asphalt (10) is ≥96%, the content of quinoline insoluble matter is ≤20%, and the content of mesophase asphalt in the produced isotropic asphalt (11) is ≤10%.

[0012] The present invention adopts the above technical solution, which has the following beneficial effects compared with the prior art: (1) Using a conical centrifuge, the material is forced to gather light liquid at the upper part and heavy liquid at the lower part during high-speed rotation at a specific cone angle, greatly improving the separation capacity of the centrifuge. (2) Stable mesophase content: By adjusting the centrifuge feed rate, centrifugal temperature and centrifuge speed, the purity of the mesophase asphalt can be ensured to be no less than 96% and the mesophase content of the isotropic asphalt can be ensured to be no more than 10%. (3) When the temperature of the polymer solution reaches above 320°C, cracking and coking are very likely to occur. However, the use of centrifugal separation instead of traditional high-temperature flash separation avoids the occurrence of cracking and coking of the polymer solution and greatly reduces the content of quinoline insolubles in the intermediate phase asphalt. (4) The intermediate phase asphalt is purified by centrifugation, which is simple to operate and can be operated continuously. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the present invention, wherein: 1-polymerization liquid buffer tank; 2-sampling port; 3-flow regulating valve; 4-vertebral centrifuge; 5, 6-quality monitoring ports; 7-mesophase asphalt tank; 8-isotropic asphalt tank; 9-polymerization liquid; 10-mesophase asphalt; 11-isotropic asphalt. DETAILED DESCRIPTION

[0014] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions made to the present invention without departing from the concept of the present solution are all within the scope of protection of the present invention.

[0015] Example 1 A continuous separation method for mesophase asphalt, by adjusting the opening of the heat transfer oil return valve, the whole system is preheated to 250°C; 0.2MPa nitrogen is filled into the polymerization liquid buffer tank, and the polymerization liquid with a mesophase asphalt content of 60% is passed from the polymerization liquid buffer tank to a vertebral centrifuge, and the polymerization liquid feed rate is controlled to be 15KG / h by a regulating valve, and the centrifuge speed is 2500r / min. Isotropic asphalt is produced from the upper outlet of the centrifuge, and mesophase asphalt is produced from the lower outlet of the centrifuge. The purity of the mesophase asphalt detected by a polarizing microscope is 98%, the content of quinoline insoluble matter detected by a solvent extraction method is 12.3%, and the content of mesophase asphalt in the isotropic asphalt is 4%.

[0016] Example 2 A continuous separation method for mesophase asphalt, by adjusting the opening of the heat transfer oil return valve, the whole system is preheated to 250°C; 0.2MPa nitrogen is filled into the polymerization liquid buffer tank, and the polymerization liquid with a mesophase asphalt content of 68% is passed from the polymerization liquid buffer tank to a vertebral centrifuge, and the polymerization liquid feed rate is controlled to be 15KG / h by a regulating valve, and the centrifuge speed is 2500r / min. Isotropic asphalt is produced from the upper outlet of the centrifuge, and mesophase asphalt is produced from the lower outlet of the centrifuge. The mesophase content in the mesophase asphalt is detected by a polarizing microscope and is 96%, and the quinoline insoluble content is detected by a solvent extraction method and is 11.5%, and the mesophase asphalt content in the isotropic asphalt is 7%.

[0017] Example 3 A continuous separation method for mesophase asphalt is provided. The whole system is preheated to 300°C by adjusting the opening of a heat transfer oil return valve. 0.2MPa of nitrogen is charged into a polymer liquid buffer tank. A polymer liquid with a mesophase asphalt content of 68% is passed from the polymer liquid buffer tank into a vertebral centrifuge. The polymer liquid feed rate is controlled to be 15KG / h by a regulating valve, and the centrifuge speed is 2500r / min. Isotropic asphalt is produced from the upper outlet of the centrifuge, and mesophase asphalt is produced from the lower outlet of the centrifuge. The mesophase content in the mesophase asphalt is 98% when detected by a polarizing microscope, the quinoline insoluble content is 12.5% ​​when detected by a solvent extraction method, and the mesophase asphalt content in the isotropic asphalt is 3%.

[0018] Example 4 A continuous separation method of mesophase asphalt, by adjusting the opening of the heat transfer oil return valve, the whole system is preheated to 250°C; 0.2MPa nitrogen is filled into the polymerization liquid buffer tank, and the polymerization liquid with a mesophase asphalt content of 68% is passed from the polymerization liquid buffer tank to a vertebral centrifuge, and the polymerization liquid feed rate is controlled to be 15KG / h by a regulating valve, and the centrifuge speed is 3000r / min. Isotropic asphalt is produced from the upper outlet of the centrifuge, and mesophase asphalt is produced from the lower outlet of the centrifuge, and the product is qualified after one centrifugation. The mesophase content in the mesophase asphalt is detected by a polarizing microscope and is 97%, the quinoline insoluble content is detected by a solvent extraction method and is 12.1%, and the mesophase asphalt content in the isotropic asphalt is 5%.

[0019] Example 5 A continuous separation method of mesophase asphalt, by adjusting the opening of the heat transfer oil return valve, the whole system is preheated to 250°C; 0.2MPa nitrogen is filled into the polymerization liquid buffer tank, and the polymerization liquid with a mesophase asphalt content of 68% is passed from the polymerization liquid buffer tank to a vertebral centrifuge, and the polymerization liquid feed rate is controlled to be 10KG / h by a regulating valve, and the centrifuge speed is 2500r / min. Isotropic asphalt is produced from the upper outlet of the centrifuge, and mesophase asphalt is produced from the lower outlet of the centrifuge, and the product is qualified after one centrifugation. The mesophase content in the mesophase asphalt is detected by a polarizing microscope and is 98%, the quinoline insoluble content is detected by a solvent extraction method and is 12.5%, and the mesophase asphalt content in the isotropic asphalt is 4%.

[0020] Comparative Example 1 A continuous separation method for mesophase asphalt, by adjusting the opening of the heat transfer oil return valve, the whole system is preheated to 340°C; 0.2MPa nitrogen is filled into the polymerization liquid buffer tank, and the polymerization liquid with a mesophase asphalt content of 60% is passed from the polymerization liquid buffer tank to a vertebral centrifuge, and the polymerization liquid feed rate is controlled to be 15KG / h by a regulating valve, and the centrifuge speed is 2500r / min. Isotropic asphalt is produced from the upper outlet of the centrifuge, and mesophase asphalt is produced from the lower outlet of the centrifuge. The purity of the mesophase asphalt detected by a polarizing microscope is 99%, the content of quinoline insoluble matter detected by a solvent extraction method is 25.3%, and the content of mesophase asphalt in the isotropic asphalt is 2%.

[0021] Comparative Example 2 A continuous separation method for mesophase asphalt, by adjusting the opening of the heat transfer oil return valve, the whole system is preheated to 340°C; 0.2MPa nitrogen is filled into the polymerization liquid buffer tank, and the polymerization liquid with a mesophase asphalt content of 68% is passed from the polymerization liquid buffer tank to a vertebral centrifuge, and the polymerization liquid feed rate is controlled to be 15KG / h by a regulating valve, and the centrifuge speed is 2500r / min. Isotropic asphalt is produced from the upper outlet of the centrifuge, and mesophase asphalt is produced from the lower outlet of the centrifuge. The mesophase content in the mesophase asphalt is detected by a polarizing microscope and is 99%, and the quinoline insoluble content is detected by a solvent extraction method and is 26.7%, and the mesophase asphalt content in the isotropic asphalt is 3%.

[0022] Comparative Example 3 A continuous separation method for mesophase asphalt, by adjusting the opening of the heat transfer oil return valve, the whole system is preheated to 340°C; 0.2MPa nitrogen is filled into the polymerization liquid buffer tank, and the polymerization liquid with a mesophase asphalt content of 68% is passed from the polymerization liquid buffer tank to a vertebral centrifuge, and the polymerization liquid feed rate is controlled to be 15KG / h by a regulating valve, and the centrifuge speed is 3000r / min. Isotropic asphalt is produced from the upper outlet of the centrifuge, and mesophase asphalt is produced from the lower outlet of the centrifuge. The mesophase content in the mesophase asphalt is detected by a polarizing microscope and is 99%, and the quinoline insoluble content is detected by a solvent extraction method and is 27.5%, and the mesophase asphalt content in the isotropic asphalt is 2%.

[0025] Comparative Example 4 A continuous separation method for mesophase asphalt, by adjusting the opening of the heat transfer oil return valve, the whole system is preheated to 340°C; 0.2MPa nitrogen is filled into the polymerization liquid buffer tank, and the polymerization liquid with a mesophase asphalt content of 68% is passed from the polymerization liquid buffer tank to a vertebral centrifuge, and the polymerization liquid feed rate is controlled to be 10KG / h by a regulating valve, and the centrifuge speed is 2500r / min. Isotropic asphalt is produced from the upper outlet of the centrifuge, and mesophase asphalt is produced from the lower outlet of the centrifuge. The mesophase content in the mesophase asphalt is detected by a polarizing microscope and is 99%, the quinoline insoluble content is detected by a solvent extraction method and is 26.8%, and the mesophase asphalt content in the isotropic asphalt is 2%.

[0026] The mesophase asphalt prepared in the present invention is tested, and the mesophase content detection method is implemented in accordance with "GB / T 38396-2019", and the quinoline insoluble matter detection method is implemented in accordance with "GB / T 2293-2019".

[0026] Summary of Examples and Comparative Examples

Claims

1. A method for continuous separation of mesophase asphalt, characterized in that: The polymerization liquid (9) is introduced into the vertebral centrifuge (4) from the polymerization liquid buffer tank (1), and the polymerization liquid feed rate is controlled by the flow regulating valve (3) to be 5-20KG / h, the polymerization liquid feed temperature is 200-350°C, and the centrifuge inlet pressure is 0.05-0.5Mpa; the isotropic asphalt is produced from the upper outlet of the centrifuge, and after passing the test, it enters the isotropic asphalt tank (8); the mesophase asphalt is produced from the lower outlet of the centrifuge, and after passing the test, it enters the mesophase asphalt tank (7).

2. The method for continuous separation of mesophase pitch according to claim 1, characterized in that: The content of mesophase asphalt in the polymerization liquid is 60-70%.

3. The method for continuous separation of mesophase pitch according to claim 1, characterized in that: The rotation speed of the vertebral centrifuge is 0-3000r / min, the motor speed can be adjusted by variable frequency, and the maximum operating temperature of the vertebral centrifuge is 350℃.

4. The method for continuous separation of mesophase pitch according to claim 1, characterized in that: The polymer liquid delivery pipeline is provided with a flow regulating valve (3) to adjust the feed rate of the polymer liquid; the polymer liquid delivery pipeline is provided with a sampling port (2) to regularly sample and monitor the change of the intermediate phase asphalt content in the polymer liquid; the polymer liquid delivery pipeline and valves are both jacketed for heating, the heating temperature is 200-350°C, and the heat medium is high-pressure steam or high-temperature heat transfer oil.

5. The method for continuous separation of mesophase pitch according to claim 1, characterized in that: Quality monitoring ports (6) and (5) are respectively provided on the conveying pipelines from the vertebral centrifuge to the isotropic asphalt tank and the mesophase asphalt tank. The centrifugal temperature and the centrifuge speed are adjusted in time according to the monitoring data to ensure the product quality. The conveying pipeline adopts jacket heating, the heating temperature is 250-350°C, and the heat medium is high-pressure steam, high-temperature heat transfer oil or molten salt.

6. The method for continuous separation of mesophase pitch according to claim 1, characterized in that: The purity of the produced mesophase asphalt (10) is ≥96%, the content of quinoline insoluble matter is ≤20%, and the content of mesophase asphalt in the produced isotropic asphalt (11) is ≤10%.

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