Spinning pitch purification device and method

Abstract

The invention discloses a spinning pitch purification device which comprises a pitch tank, a partition plate is arranged in the asphalt tank and divides the interior of the asphalt tank into a first grid and a second grid; the pitch tank is provided with a mesophase pitch feed pipe and a pitch discharge port which are communicated with the first grid, and a high-purity pitch outlet which is communicated with the second grid; a nitrogen inlet and an extraction opening are further formed in the asphalt tank; and an overflow speed regulating structure is arranged at the top of the partition plate. The invention also discloses a spinning pitch purification method. According to the method, the content of light components and heavy components of the spinning pitch can be reduced, so that the molecular weight distribution of the mesophase pitch is concentrated, the mesophase pitch is purified and homogenized, the high-purity spinning pitch is obtained, and the spinning manufacturability and stability of the spinning pitch are improved.

Description

Technical Field

[0001] The present invention relates to the purification technology of mesophase pitch spinning, and more specifically, to a spinning pitch purification device and method. Background Art

[0002] Mesophase pitch is an excellent raw material for preparing high-performance carbon materials such as high-performance pitch-based carbon fibers and high thermal conductivity foam carbon. During the preparation of these high-performance carbon materials, the raw material requirements for mesophase pitch are narrow molecular weight distribution, and the contents of light components and macromolecular heavy components in mesophase pitch need to be controlled. Since the slurry and its asphalt products as by-products of coal and petrochemical industries have high impurity contents and complex compositions, during the preparation of mesophase pitch, it is often necessary to modify the slurry and asphalt obtained by processing natural raw materials such as petroleum and coal to remove impurities and adjust the molecular structure of the raw materials.

[0003] In existing patent applications, for example, Patent Publication No. CN113528178B discloses a method for preparing mesophase pitch using catalytic cracking slurry, belonging to the field of petroleum asphalt. This method uses this low-value by-product catalytic cracking slurry as a raw material and graphene as an additive. In the first step, petroleum asphalt with a high softening point, narrow molecular weight distribution, and high regularity is prepared, and in the second step, high-performance mesophase pitch is directly prepared by thermal polycondensation.

[0004] Another example is Patent Publication No. CN110272757B, which discloses a method for preparing mesophase pitch. The technical key points of this patent are: using petroleum asphalt as a raw material, adding an additive, and performing heat treatment at 380 - 420 °C for 2 - 10 hours under nitrogen protection. The organic molecules in the additive undergo heterogeneous nucleation and condensation reactions with the ash in the raw material to form anisotropic asphalt spheres encapsulating the ash. After standing and settling at 300 - 380 °C for 2 - 10 hours, the upper isotropic asphalt and the lower anisotropic asphalt are separated. Taking the upper isotropic asphalt as the raw material, heat treatment is performed at 380 - 420 °C for 5 - 15 hours under nitrogen protection to obtain high-quality mesophase pitch.

[0005] Another example is Patent Publication No. CN110776943B, which discloses a method for preparing spinnable mesophase pitch. The technical key points of this patent are: crushing high softening point petroleum asphalt and then performing hot extraction and filtration to obtain purified petroleum asphalt; mixing the purified petroleum asphalt with octahydrophenanthrene or a hydrogen donor reagent containing octahydrophenanthrene, and then performing a thermal polycondensation reaction; after the thermal polycondensation reaction is completed, reducing the pressure, and blowing at 370 - 420 °C with stirring to obtain mesophase pitch.

[0006] However, the above patent technologies are all related to the preparation of mesophase pitch and do not target the re-purification process of mesophase pitch. Summary of the Invention

[0007] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a spinning pitch purification device and method, which can reduce the content of light components and heavy components in the spinning pitch, make the molecular weight distribution of the mesophase pitch concentrated, achieve the purification and homogenization of the mesophase pitch, obtain high-purity spinning pitch, and improve the spinning processability and stability of the spinning pitch.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The first aspect of the present invention provides a spinning pitch purification device, including a pitch tank;

[0010] A partition is provided inside the pitch tank, dividing the interior of the pitch tank into a first compartment and a second compartment;

[0011] The pitch tank is provided with a mesophase pitch inlet pipe, a pitch discharge port communicating with the first compartment, and a high-purity pitch outlet communicating with the second compartment;

[0012] The pitch tank is also provided with a nitrogen inlet and an air extraction port;

[0013] An overflow speed regulation structure is provided at the top of the partition.

[0014] Preferably, the overflow speed regulation structure includes an inclined plate and an adjustable-speed rotating cylinder;

[0015] One end of the inclined plate is connected to the top of the partition, and the other end of the inclined plate is inclined downward towards the second compartment;

[0016] The adjustable-speed rotating cylinder is arranged above the inclined plate and has a gap with the upper surface of the inclined plate.

[0017] Preferably, the inclination angle of the inclined plate is 5 to 30°.

[0018] Preferably, the gap between the adjustable-speed rotating cylinder and the inclined plate is 0.5 to 30 mm.

[0019] The second aspect of the present invention provides a spinning pitch purification method, which uses the spinning pitch purification device provided in the first aspect of the present invention to perform the following operations:

[0020] The mesophase pitch enters the first compartment of the pitch tank through the mesophase pitch inlet pipe. When the liquid level of the mesophase pitch reaches the height of the partition, the mesophase pitch will overflow to the second compartment through the inclined plate, and by adjusting the speed of the adjustable-speed rotating cylinder, the film thickness of the mesophase pitch on the inclined plate can be controlled;

[0021] Then, high-temperature nitrogen is introduced through the nitrogen inlet, and at the same time, light components are extracted through the air extraction port to keep the inside of the asphalt tank in a negative pressure state;

[0022] When the second compartment is filled with mesophase pitch, keep it at a constant temperature, and then discharge high-purity spinning pitch from the high-purity pitch outlet and heavy mesophase pitch from the pitch discharge port respectively.

[0023] Preferably, the mesophase pitch is heated externally to 300 - 380 °C and then fed into the first compartment.

[0024] Preferably, the speed of the adjustable-speed rotating cylinder is 0 - 60 rpm.

[0025] Preferably, the temperature of the high-temperature nitrogen is above 280 °C.

[0026] Preferably, the light components are extracted through a vacuum pump at the air extraction port to keep the negative pressure in the asphalt tank between -10 and -90 KPa.

[0027] Preferably, the mesophase pitch is kept at a constant temperature in the second compartment for 1 - 20 h.

[0028] The spinning pitch purification device and method provided by the present invention can make the atmospheric pressure weight loss of the purified mesophase pitch at 380 °C less than 2%, and greatly improve the spinning time and stability. At the same time, the co-produced heavy mesophase pitch can be foamed to obtain foam carbon with better quality. Description of the Drawings

[0029] Figure 1 It is a schematic diagram of the frame structure of the spinning pitch purification device of the present invention. Detailed Embodiments

[0030] In order to better understand the above technical solutions of the present invention, the technical solutions of the present invention will be further described below with reference to the drawings and embodiments.

[0031] Combined with Figure 1 As shown, a spinning pitch purification device provided by the present invention includes an asphalt tank 9.

[0032] A partition 7 is provided inside the asphalt tank 9 to divide the inside of the asphalt tank 9 into a first compartment 91 and a second compartment 92.

[0033] The asphalt tank 9 is provided with a mesophase pitch feed pipe 1 communicating with the first compartment 91, a pitch discharge port 8, and a high-purity pitch outlet 6 communicating with the second compartment 92.

[0034] The asphalt tank 9 is further provided with a nitrogen inlet 4 and an air extraction port 5.

[0035] An overflow speed control structure is provided at the top of the partition 7.

[0036] The overflow speed control structure includes an inclined plate 3 and a speed-adjustable rotating cylinder 2.

[0037] One end of the inclined plate 3 is connected to the top of the partition plate 7, and the other end of the inclined plate 3 slopes downward and is arranged towards the second compartment 92. The inclination angle of the inclined plate 3 is 5-30°.

[0038] The speed-adjustable rotating cylinder 2 is arranged above the inclined plate 3, and there is a gap between the speed-adjustable rotating cylinder 2 and the upper surface of the inclined plate 3. The gap is 0.5-30 mm.

[0039] Combined with Figure 1 As shown, the present invention also provides a method for purifying spinning pitch, which uses the spinning pitch purification device of the present invention to perform the following operations:

[0040] The mesophase pitch enters the first compartment 91 of the pitch tank 9 through the mesophase pitch feed pipe 1. When the liquid level of the mesophase pitch reaches the height of the partition plate 7, the mesophase pitch will overflow to the second compartment 92 through the inclined plate 3. The overflow speed can be controlled by the feed speed of the mesophase pitch and the speed-adjustable rotating cylinder 2. By adjusting the speed of the speed-adjustable rotating cylinder 2, the film thickness of the mesophase pitch on the inclined plate 3 can be controlled.

[0041] Then, high-temperature nitrogen is introduced through the nitrogen inlet 4, and at the same time, the light components are extracted through the air extraction port 5, and a certain negative pressure state is maintained in the pitch tank 9.

[0042] When the second compartment 92 is filled with mesophase pitch, after maintaining a constant temperature for a period of time, high-purity spinning pitch is discharged from the high-purity pitch outlet 6, and heavy mesophase pitch for producing high-thermal-conductivity foam carbon is discharged from the pitch discharge port 8.

[0043] Through the spinning pitch purification device of the present invention, the components with slightly higher density in the mesophase pitch are separated, and at the same time, the components with lower density are vaporized and discharged under the action of film formation and vacuum, obtaining mesophase pitch with a narrower molecular weight distribution. This pitch has moderate rheological properties and excellent spinning properties. At the same time, a mesophase pitch for preparing high-thermal-conductivity foam carbon is co-produced. The specific steps are as follows:

[0044] S1, heat the mesophase pitch to 300-380 °C through external heating and feed it into the first compartment 91 of the pitch tank 9. The pitch tank 9 uses a vacuum pump to extract light components through the air extraction port 5, maintains -10 to -90 KPa (gauge pressure), and the pitch tank 9 is thermally insulated at 300-380 °C;

[0045] S2, the mesophase pitch in the first compartment 91 of the pitch tank 9 is gradually stratified according to different densities. The components with higher density remain at the bottom of the tank, and the components with lower density accumulate in the upper part of the first compartment 91 of the pitch tank 9 and overflow to the inclined plate 3 through the partition plate 7. The inclination angle of the inclined plate 3 is 5-30°;

[0046] S3. The gap between the speed-adjustable rotating cylinder 2 and the inclined plate 3 is controlled between 0.5 and 3 mm. The speed of the speed-adjustable rotating cylinder 2 can be adjusted between 0 and 60 rpm to control the thickness of the mesophase pitch on the inclined plate 3 between 0.5 and 5 mm. At the same time, a small amount of hot nitrogen above 280 °C is introduced to remove small molecules with a boiling point less than 380 °C from the mesophase pitch.

[0047] S4. After the second grid 92 of the pitch tank 9 is filled, it is stabilized for 1 to 20 h. The mesophase pitch in the first grid 91 and the second grid 02 is respectively pumped out from the pitch discharge port 8 at the bottom and the high-purity pitch outlet 6 through a high-temperature pump.

[0048] Example 1

[0049] In this Example 1, a mesophase pitch raw material with a softening point of 290 °C is used, the TG weight loss at 380 °C is 6%, it is heated to 320 °C and enters the pitch tank 9. The insulation temperature of the pitch tank 9 is 320 °C, the rotation speed of the speed-adjustable rotating cylinder 2 is 30 rpm, the gap between the speed-adjustable rotating cylinder 2 and the inclined plate 3 is controlled at 2 mm, the inclination angle of the inclined plate 3 is 20°, the vacuum degree of the pitch tank 9 is maintained at -80 to -90 KPa, and the stable residence time after filling is 15 h. The obtained purified mesophase pitch has a softening point of 292 °C, the TG weight loss at 380 °C is 1.5%, and the spinning time is extended by 60%.

[0050] Example 2

[0051] In this Example 2, a mesophase pitch raw material with a softening point of 290 °C is used, the TG weight loss at 380 °C is 6%, it is heated to 360 °C and enters the pitch tank 9. The insulation temperature of the pitch tank 9 is 360 °C, the rotation speed of the speed-adjustable rotating cylinder 2 is 10 rpm, the gap between the speed-adjustable rotating cylinder 2 and the inclined plate 3 is controlled at 2 mm, the inclination angle of the inclined plate 3 is 15°, the vacuum degree of the pitch tank 9 is maintained at -80 to -90 KPa, and the stable residence time after filling is 12 h. The obtained purified mesophase pitch has a softening point of 293 °C, the TG weight loss at 380 °C is 1%, and the spinning time is extended by 100%.

[0052] Example 3

[0053] In this Example 3, a mesophase pitch raw material with a softening point of 290 °C is used. The TG weight loss at 380 °C is 6%. It is heated to 340 °C and enters the asphalt tank. The holding temperature of the asphalt tank is 340 °C. The rotation speed of the adjustable-speed rotating drum 2 is 15 rpm. The gap between the adjustable-speed rotating drum 2 and the inclined plate 3 is controlled at 2 mm. The inclination angle of the inclined plate 3 is 15°. The vacuum degree of the asphalt tank 9 is maintained at -80 to -90 KPa. After being filled, the stable residence time is 10 h. The obtained purified mesophase pitch has a softening point of 293 °C, and the TG weight loss at 380 °C is 0.8%. The spinning time is extended by 120%.

[0054] Those of ordinary skill in the art in this technical field should recognize that the above embodiments are only used to illustrate the present invention, rather than to limit the present invention. As long as it is within the scope of the substantial spirit of the present invention, the changes and modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A spinning pitch purification device, characterized in that: It includes an asphalt tank; A partition is provided inside the asphalt tank, dividing the interior of the asphalt tank into a first compartment and a second compartment; The asphalt tank is provided with an intermediate phase asphalt feed pipe and an asphalt discharge port communicating with the first compartment, and a high-purity asphalt outlet communicating with the second compartment; The asphalt tank is also provided with a nitrogen inlet and an air extraction port; An overflow speed control structure is provided at the top of the partition; 2. The spinning pitch purification device according to claim 1, characterized in that: The overflow speed control structure includes an inclined plate and an adjustable speed rotating cylinder; One end of the inclined plate is connected to the top of the partition, and the other end of the inclined plate is inclined downward towards the second compartment; The adjustable speed rotating cylinder is arranged above the inclined plate and has a gap with the upper surface of the inclined plate; 3. The spinning pitch purification device according to claim 1, characterized in that: The inclination angle of the inclined plate is 5 - 30°; 4. The spinning pitch purification device according to claim 1, characterized in that: The gap between the adjustable speed rotating cylinder and the inclined plate is 0.5 - 30 mm; 5. A method for purifying spinning pitch, characterized in that, The following operations are realized by using the spinning asphalt purification device according to any one of claims 1 - 4: Intermediate phase asphalt enters the first compartment of the asphalt tank through the intermediate phase asphalt feed pipe. When the liquid level of the intermediate phase asphalt reaches the height of the partition, the intermediate phase asphalt will overflow to the second compartment through the inclined plate. By adjusting the speed of the adjustable speed rotating cylinder, the film thickness of the intermediate phase asphalt on the inclined plate is controlled; Then, high-temperature nitrogen is introduced through the nitrogen inlet, and at the same time, light components are extracted through the air extraction port to keep the interior of the asphalt tank in a negative pressure state; When the second compartment is filled with intermediate phase asphalt, keep it at a constant temperature, and then high-purity spinning asphalt is discharged from the high-purity asphalt outlet, and heavy intermediate phase asphalt is discharged from the asphalt discharge port; 6. The spinning pitch purification method according to claim 5, wherein: The intermediate phase asphalt is externally heated to 300 - 380 °C and then fed into the first compartment; 7. The spinning pitch purification method according to claim 5, characterized in that: The speed of the adjustable speed rotating cylinder is 0 - 60 rpm; 8. The spinning pitch purification method according to claim 5, characterized in that: The temperature of the high-temperature nitrogen is above 280 °C; 9. The spinning pitch purification method according to claim 5, characterized in that: The air extraction port extracts light components through a vacuum pump to keep the negative pressure in the asphalt tank between -10 and -90 KPa; 10. The spinning pitch purification method according to claim 5, characterized in that: The intermediate phase asphalt is kept at a constant temperature in the second compartment for 1 - 20 h.

Images