A method and equipment for resource utilization of tail gas during the densification process of carbon / carbon composites

Abstract

The present invention discloses a method and equipment for resource utilization of tail gas in the densification process of carbon / carbon composites, belonging to the technical field of separation and utilization of tail gas in material processing. Since asphalt produces various solid, liquid and gas products under carbonization conditions, the present invention uses a condensation gas-liquid separator to separate gas, liquid and solid, and the separation steps are very simple and efficient; the gas is pumped from the condenser to the gas holder by a Roots blower for storage. When deposition is required for the product, the gas is pumped into the deposition furnace by the vacuum pump of the deposition furnace and used as the raw material for gas-phase deposition carbon in the deposition furnace, realizing partial resource utilization; further, the tail gas generated during the deposition process, as well as the solid-liquid products of carbonization, can be discharged into the combustion chamber of the burner for combustion, and the heat energy of combustion can be introduced into the impregnation furnace for heating, realizing a higher resource utilization rate.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas separation and utilization in material processing, and particularly to a method and equipment for resource utilization of waste gas in the densification process of carbon / carbon composites. Background Art

[0002] Carbon / carbon composite material (c-c composite or carbon-carbon composite material) is a carbon matrix composite material reinforced by carbon fibers and their fabrics. It has excellent friction and wear properties, and has the advantages of light weight, low noise, shock absorption, braking performance and good safety. It is considered to be one of the most promising high-temperature materials and has been widely used in the fields of aerospace, automotive industry, medicine, etc., such as rocket engine nozzles and their throat liners, nose caps of space shuttles and thermal protection systems for leading edges of wings, and aircraft brake discs.

[0003] Generally, during the preparation of carbon / carbon composite materials by the CVI method, a large amount of multiphase impurities such as tar, carbon black, coke particles, carbon fibers, condensable macromolecules, etc. and unreacted carbon source gases need to be pumped out of the furnace through the vacuum exhaust system of the CVI furnace. These impurities entering the vacuum exhaust system of the CVI furnace will seriously pollute, block pipelines, damage valves, monitoring equipment, vacuum pumps, etc. on it, and seriously affect the continuous and reliable operation of the CVI furnace.

[0004] In the current carbon / carbon composite material processing technology we adopt, since the carbon fiber preform (the carbon fiber preform is the skeleton of the carbon / carbon composite material) product enters the vacuum pressure impregnation tank for impregnation after CVI, and the impregnation uses modified asphalt, the asphalt will enter the carbonization process after impregnation, and the asphalt will produce solid carbon, non-condensable gas, oil and other products under the carbonization conditions. Since the previous process adopted a cyclic treatment method at this step (as shown in the attached Figure 1 description, the cyclic treatment of the carbonization and impregnation processes), but did not separate the products in the production process more refinedly, and the resource utilization rate is not high. Therefore, how to process various products more efficiently and effectively improve the efficiency of resource recycling is a problem that needs to be further solved. Summary of the Invention

[0005] The purpose of the present invention is to solve the above problems, and provide a method and equipment for resource utilization of waste gas in the densification process of carbon / carbon composites. After separating the solid-liquid products generated by the modified asphalt during the high-pressure impregnation process, the waste gas is burned through a radiator, and at the same time, the heat generated by the combustion is introduced into the impregnation furnace for utilization; among them, the burner is designed in a targeted multi-stage manner, which can burn the waste gas more fully, reduce the emission of harmful substances, and can efficiently introduce the heat of each combustion chamber into the heat conduction tube to improve the utilization rate of thermal energy.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for resource utilization of tail gas in the densification process of carbon / carbon composite materials, comprising the following steps:

[0007] A. The carbon-carbon composite material product undergoes CVI and then enters an impregnation furnace for impregnation.

[0008] B. The impregnation uses modified asphalt. During the high-pressure impregnation process, the asphalt is a product obtained by further thermal processing of coal tar or petroleum processing by-products. It is a mixture of countless organic substances with a multi-nuclear condensed aromatic hydrocarbon as the main body, an extremely wide molecular weight distribution, and different melting points. The impregnated asphalt then enters the carbonization process, and the asphalt will produce products such as solid carbon, non-condensable gas, and oil under the carbonization conditions.

[0009] C. The carbonization tail gas is condensed to separate gas, liquid, and solid. The liquid and solid form a solid-liquid mixture and precipitate at the lower part of the condenser, which can be taken out later and put into a burner for combustion.

[0010] D. The gas is pumped from the condenser to a gas holder by a Roots blower for storage.

[0011] E. When deposition is required, the gas is pumped into the deposition furnace by the vacuum pump of the deposition furnace and used as the raw material for gas-phase deposition carbon in the deposition furnace.

[0012] F. The tail gas generated during the deposition process is discharged into the combustion chamber of the burner for combustion after passing through the tail gas treatment system.

[0013] G. The burner burns the solid / liquid mixture carbonized and the tail gas discharged from the deposition furnace, and the heat generated by the combustion is conveyed to the impregnation furnace for heating through a heat conduction pipe connected to the burner.

[0014] Furthermore, the temperature of the impregnation condition in step B is 200 - 350 °C, the pressure is 3 - 10 MPa, and in the products of the asphalt under the impregnation condition, the solid carbon content is 9.3% - 11.3%, the content of aromatic hydrocarbons below C8 in the non-condensable gas is 68.6% - 71.6%, the content of phenol in the non-condensable gas is 1.8% - 2.4%, and the oil content is 16 - 18%.

[0015] In addition, the present invention also discloses a device for resource utilization of the tail gas in the densification process of carbon / carbon composites, which includes a burner. The burner is supported and fixed by a bracket, and the burner is connected to an oxygen delivery pipe. Inside the burner, it is separated into upper and lower two-stage combustion chambers by a partition plate. The lower layer is the primary combustion chamber, and the upper layer is the secondary combustion chamber. The bottom plate of the primary combustion chamber is provided with a tail gas inlet connected to a tail gas discharge pipe. On both sides of the tail gas inlet on the bottom plate of the primary combustion chamber, movable baffles are symmetrically arranged, and one side of the baffle is connected to a scraper; through holes are provided on the partition plate, and movable sealing plates are arranged at the through holes; igniters are arranged beside the through hole of the partition plate and beside the tail gas inlet; the outer walls of both the primary combustion chamber and the secondary combustion chamber are connected to heat conduction pipes.

[0016] Further, the bottom of the bottom plate of the primary combustion chamber is a horizontal straight plate, and both sides of the horizontal straight plate are symmetrically inclined plate structures. The bottom of the baffle is hinged to the inclined plate; on the inclined plate of the bottom plate of the primary combustion chamber, rotating shafts are installed through symmetrically arranged mounting plates, and the bottom end of the baffle is connected to the rotating shaft.

[0017] Further, one side of the baffle is hinged to a connecting rod, and the other end of the connecting rod is connected to a scraper. The side wall of the connecting rod is connected to a support column on the inner wall of the primary combustion chamber through a bearing.

[0018] Further, the connecting rod is connected to the scraper through a second spring; the scraper is in contact with the inner wall of the primary combustion chamber provided with an observation window.

[0019] Further, the upper wall of the partition plate at the through hole is a concave structure, and the bottom surface of the sealing plate is a convex structure that matches the concave surface at the through hole; the bottom surface of the sealing plate is connected to an elastic limiting component.

[0020] Further, the elastic limiting component includes a first spring connected to the bottom surface of the sealing plate. The bottom end of the first spring is connected to a mounting frame. The side plate of the mounting frame is connected to the bottom surface of the partition plate, and the first spring is connected to the bottom plate of the mounting frame.

[0021] Further, a heat conduction plate is arranged on the side wall of the primary combustion chamber, and the outside of the heat conduction plate is shrouded by a heat conduction channel; a hot gas outlet is arranged on the side wall of the secondary combustion chamber, and the hot gas outlet is connected to the heat conduction channel. The upper end of the heat conduction channel is connected to the heat conduction pipe.

[0022] Further, the heat conduction channel is composed of a heat insulation frame and the side walls of the primary combustion chamber and the secondary combustion chamber; the heat conduction plate penetrates through the primary combustion chamber; the hot gas outlet is in an inclined opening structure.

[0023] The beneficial effects of the present invention:

[0024] The method of the present invention can efficiently separate and collect the tail gas generated during the impregnation process in the processing, and then use a burner for combustion treatment. At the same time, the heat generated by combustion is reused to improve the resource recycling utilization rate. Since the impregnation process uses modified asphalt, and asphalt is a product further thermally processed from by-products of coal tar or petroleum processing, it is a mixture of countless organic substances with a multi-nuclear condensed aromatic hydrocarbon as the main body, a very wide molecular weight distribution, and different melting points. Asphalt produces various solid, liquid, and gas products under impregnation conditions. Using a condensing gas-liquid separator to separate gas, liquid, and solid, the separation steps are very simple and efficient; the gas is pumped from the condenser to the gas holder by a Roots blower for storage. When deposition is required, the gas is pumped into the deposition furnace by the vacuum pump of the deposition furnace and used as the raw material for gas-phase deposition carbon in the deposition furnace, achieving partial resource utilization; further, the tail gas generated during the deposition process is discharged into the combustion chamber of the burner for combustion after passing through the tail gas treatment system, and the heat energy of combustion can be introduced into the impregnation furnace for heating.

[0025] In order to solve the problem of insufficient gas combustion, the burner of the present invention divides the combustion chamber inside the burner into a lower first combustion chamber and an upper second combustion chamber through a partition plate, and through holes are provided on the partition plate, and the through holes are sealed by a movable sealing plate. Since symmetrical baffles are provided inside the first combustion chamber, forming a smaller combustion space, and the bottom of the baffle is hinged; when the tail gas enters the first combustion chamber from the bottom and is ignited, the instantaneous expansion will push the baffle to both sides, and the baffle rotates around the bottom shaft; since one side of the baffle is connected to a scraper through a connecting rod and a second spring, and the middle position of the connecting rod is connected to a support through a bearing, the connecting rod can rotate around the support. When the baffle moves, it can drive the connecting rod to rotate, and then push the scraper through the second spring to scrape off the residues on the inner wall of the first combustion chamber and the observation window, not only reducing the residues, but also preventing the observation window from being blocked by the accumulated residues and unable to observe the combustion situation inside the combustion chamber.

[0026] When the internal temperature of the first combustion chamber rises sharply and the pressure increases, the sealing plate above the through hole of the partition plate can be flushed open, so that the gas continues to enter the upper second combustion chamber and contacts with a larger area of oxygen, which can promote more complete combustion of the tail gas. At the same time, a heat conducting plate is provided on the inner wall of the first combustion chamber to conduct heat into the heat conducting channel; the hot gas in the second combustion chamber can directly enter the heat conducting channel and the heat conducting tube for recycling, improving the resource utilization rate of various products in the processing process.

[0027] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned advantages simultaneously. Brief Description of the Drawings

[0028] Figure 1It is a schematic diagram of the process flow of traditional process methods.

[0029] Figure 2 It is a schematic diagram of the process flow of the present invention.

[0030] Figure 3 It is an overall schematic diagram of the burner of the present invention.

[0031] Figure 4 It is a schematic diagram of the internal structure of the burner of the present invention.

[0032] Figure 5 It is a schematic diagram of the installation structure of the scraper of the present invention.

[0033] Figure 6 It is a schematic diagram of the installation of the sealing plate of the present invention.

[0034] Figure 7 It is a schematic diagram of the installation of the connecting rod of the present invention.

[0035] The text markings in the figure are as follows: 1. Bracket; 2. Combustion chamber; 3. Tail gas inlet; 4. Heat conduction tube; 5. Hot gas outlet; 6. Partition board; 7. Sealing plate; 8. Igniter; 9. First spring; 10. Mounting frame; 11. Scraper; 12. Baffle; 13. Second spring; 14. Connecting rod; 15. Heat conduction plate; 16. Rotating shaft; 17. Mounting plate; 18. Heat conduction channel; 19. Support pillar; 20. Primary combustion chamber; 21. Secondary combustion chamber. Specific implementation mode

[0036] The present invention will be further explained below through examples.

[0037] A method for resource utilization of tail gas in the densification process of carbon / carbon composite materials includes the following steps:

[0038] A. The carbon-carbon composite material product undergoes CVI and then enters the impregnation furnace for impregnation.

[0039] B. The impregnation uses modified asphalt. During the high-pressure impregnation process, the asphalt is a product obtained by further thermal processing of coal tar or petroleum processing by-products. It is a mixture of countless organic substances with a multi-nuclear condensed aromatic hydrocarbon as the main body, a very wide molecular weight distribution, and different melting points. The impregnated asphalt then enters the carbonization process, and the asphalt will produce products such as solid carbon, non-condensable gas, and oil under the impregnation and carbonization conditions.

[0040] C. The carbonization tail gas is condensed to separate gas, liquid, and solid. The liquid and solid form a solid-liquid mixture and precipitate at the lower part of the condenser, which can be taken out later and put into the burner for combustion.

[0041] D. The gas is pumped from the condenser to the gas holder by a Roots blower for storage.

[0042] E. When deposition is required, gas is pumped into the deposition furnace through the vacuum pump of the deposition furnace as the raw material for gas-phase deposition of carbon in the deposition furnace.

[0043] F. The tail gas generated during the deposition process is discharged into the combustion chamber 2 of the burner for combustion after passing through the tail gas treatment system.

[0044] G. The burner burns the solid / liquid mixture carbonized and the tail gas discharged from the deposition furnace, and the heat generated by the combustion is conveyed through the heat conduction pipe 4 connected to the burner to heat the impregnation furnace.

[0045] Preferably, the temperature of the impregnation condition in step B is 200 - 350 °C, the pressure is 3 - 10 MPa. In the product of asphalt under the impregnation condition, the solid carbon content is 9.3% - 11.3%, the content of aromatic hydrocarbons below C8 in the non-condensable gas is 68.6% - 71.6%, the content of phenol in the non-condensable gas is 1.8% - 2.4%, and the oil content is 16 - 18%.

[0046] In addition, the present invention also discloses a device for utilizing the tail gas in the densification process of carbon / carbon composites, including a burner. The burner is supported and fixed by a bracket 1 and is communicated with an oxygen delivery pipe. The interior of the burner is separated by a partition plate 6 to form upper and lower combustion chambers. The lower layer is the primary combustion chamber 20, and the upper layer is the secondary combustion chamber 21. The bottom plate of the primary combustion chamber 20 is provided with a tail gas inlet 3 communicated with a tail gas discharge pipe. On both sides of the tail gas inlet 3 on the bottom plate of the primary combustion chamber 20, movable baffles 12 are symmetrically arranged, and a scraper 11 is connected to one side of the baffle 12. The partition plate 6 is provided with through holes, and movable sealing plates 7 are arranged at the through holes. Igniters 8 are arranged beside the through holes of the tail gas inlet 3 and the partition plate 6. The outer walls of the primary combustion chamber 20 and the secondary combustion chamber 21 are both connected to the heat conduction pipe 4.

[0047] Preferably, as shown in Figure 3 、 5 、6, the upper wall of the partition plate 6 at the through hole is a concave structure, and the bottom surface of the sealing plate 7 is a convex structure that matches the concave surface at the through hole. The bottom surface of the sealing plate 7 is connected to an elastic limiting component. The elastic limiting component includes a first spring 9 connected to the bottom surface of the sealing plate 7. The bottom end of the first spring 9 is connected to a mounting frame 10. The side plate of the mounting frame 10 is connected to the bottom surface of the partition plate 6, and the first spring 9 is connected to the bottom plate of the mounting frame 10. The bottom surface structure of the sealing plate 7 can effectively disperse the force of the impact, play a buffering role for the air flow, and at the same time can cooperate with the igniters 8 on both sides of the sealing plate 7 to guide the air flow to the burner 8 to ensure the ignition effect.

[0048] Preferably, as shown in Figure 3 、 4, as shown in FIGS. 5, a heat conducting plate 15 is provided on the side wall of the primary combustion chamber 20, and the outside of the heat conducting plate 15 is covered by a heat conducting channel 18; a hot gas outlet 5 is formed on the side wall of the secondary combustion chamber 21, the hot gas outlet 5 is communicated with the heat conducting channel 18, and the upper end of the heat conducting channel 18 is communicated with the heat conducting pipe 4. The heat conducting channel 18 is composed of a heat insulating frame and the side walls of the primary combustion chamber 20 and the secondary combustion chamber 21; the heat conducting plate 15 is arranged through the primary combustion chamber 20; the hot gas outlet 5 is of an inclined opening structure.

[0049] Preferably, please refer to Figure 3 , 4 , as shown in FIGS. 5, the bottom of the bottom plate of the primary combustion chamber 20 is a horizontal straight plate and both sides of the horizontal straight plate are of symmetrical inclined plate structures, and the bottom of the baffle 12 is hinged to the inclined plate; rotating shafts 16 are installed on the inclined plates of the bottom plate of the primary combustion chamber 20 through symmetrical mounting plates 17, and the bottom end of the baffle 12 is connected to the rotating shafts 16. One side of the baffle 12 is hinged with a connecting rod 14, the other end of the connecting rod 14 is connected with a scraping plate 11, and the side wall of the connecting rod 14 is connected to a support column 19 on the inner wall of the primary combustion chamber 20 through a bearing. The connecting rod 14 is connected with the scraping plate 11 through a second spring 13; the scraping plate 11 contacts the inner wall of the primary combustion chamber 20 provided with an observation window. The scraping plate 11 can scrape off the accumulated residues on the inner wall and the observation window at the same time. Cooperating with the bottom plate of the inclined plate structure of the primary combustion chamber 20, it is convenient to clean from the exhaust gas inlet 3. The second spring 13 can not only always keep the scraping plate 11 in contact with the inner wall, but when the connecting rod 14 rotates, the compressed second spring 13 is reduced in force and extends, and can also push the scraping plate 11 to scrape off the residues downward.

[0050] It should be noted that in this article, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0051] The principle and implementation manner of the present invention are expounded in this article. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for resource utilization of tail gas in the densification process of carbon / carbon composite materials. The tail gas is generated when carbon / carbon composite material products enter the impregnation furnace through CVI, are impregnated with asphalt, and then enter the carbonization process. The tail gas contains products such as solid carbon, non-condensable gas, and oil. It is characterized in that, It includes the following steps: A. The carbide tail gas is condensed to separate gas, liquid and solid; the liquid and solid form a solid-liquid mixture which precipitates at the lower part of the condenser and can be taken out later and put into a burner for combustion; B. The gas is pumped from the condenser to a gas holder by a Roots blower for storage; C. When deposition is required, the gas is pumped into the deposition furnace by the vacuum pump of the deposition furnace and used as the raw material for gas-phase deposition carbon in the deposition furnace; D. The tail gas generated during the deposition process is discharged into the combustion chamber (2) of the burner for combustion after passing through the tail gas treatment system; E. The burner burns the solid / liquid mixture carbonized and the tail gas discharged from the deposition furnace, and the heat generated by the combustion is conveyed to the impregnation furnace for heating through a heat conduction pipe (4) connected to the burner.

2. The method for resource utilization of tail gas in the densification process of carbon / carbon composite materials according to claim 1, characterized in that, The temperature of the impregnation condition is 200 - 350 °C, the pressure is 3 - 10 MPa. In the product of asphalt under the impregnation condition, the solid carbon content is 9.3% - 11.3%, the content of aromatic hydrocarbons below C8 in the non-condensable gas is 68.6% - 71.6%, the content of phenol in the non-condensable gas is 1.8% - 2.4%, and the oil content is 16 - 18%.

3. An apparatus for the resource utilization of the tail gas in the densification process of a carbon / carbon composite material according to any one of claims 1-2, which comprises a burner, the burner is supported and fixed by a bracket (1), and the burner is communicated with an oxygen delivery pipe, and is characterized in that, The interior of the burner is separated by a partition plate (6) to form upper and lower combustion chambers. The lower layer is the primary combustion chamber (20), and the upper layer is the secondary combustion chamber (21). The bottom plate of the primary combustion chamber (20) is provided with a tail gas inlet (3) connected to a tail gas discharge pipe. On both sides of the tail gas inlet (3) on the bottom plate of the primary combustion chamber (20), movable baffles (12) are symmetrically arranged. One side of the baffle (12) is connected to a scraper (11); the partition plate (6) is provided with a through hole and a movable sealing plate (7) is arranged at the through hole. Igniters (8) are arranged beside the through hole of the partition plate (6) and the tail gas inlet (3); the outer walls of both the primary combustion chamber (20) and the secondary combustion chamber (21) are connected to the heat conduction pipe (4); The upper wall of the partition plate (6) at the through hole is of a concave structure, and the bottom surface of the sealing plate (7) is a convex structure that matches the concave surface at the through hole; the bottom surface of the sealing plate (7) is connected to an elastic limit component.

4. The device for resource utilization of tail gas in the densification process of carbon / carbon composite materials according to claim 3, characterized in that, The bottom of the bottom plate of the primary combustion chamber (20) is a horizontal straight plate, and both sides of the horizontal straight plate are of a symmetrically inclined plate structure. The bottom of the baffle (12) is hinged to the inclined plate; on the inclined plate of the bottom plate of the primary combustion chamber (20), a rotating shaft (16) is installed through symmetrically arranged mounting plates (17), and the bottom end of the baffle (12) is connected to the rotating shaft (16).

5. The equipment for resource utilization of tail gas in the densification process of carbon / carbon composite materials according to claim 4, characterized in that, One side of the baffle (12) is hinged to a connecting rod (14), and the other end of the connecting rod (14) is connected to a scraper (11). The side wall of the connecting rod (14) is connected to a pillar (19) on the inner wall of the primary combustion chamber (20) through a bearing.

6. The device for resource utilization of the tail gas in the densification process of carbon / carbon composite materials according to claim 5, characterized in that, The connecting rod (14) is connected to the scraper (11) through a second spring (13); the scraper (11) contacts the inner wall of the primary combustion chamber (20) provided with an observation window.

7. An apparatus for resource utilization of tail gas in the densification process of carbon / carbon composite materials according to claim 3, characterized in that The elastic limit component includes a first spring (9) connected to the bottom surface of the sealing plate (7). The bottom end of the first spring (9) is connected to the mounting frame (10). The side plate of the mounting frame (10) is connected to the bottom surface of the partition plate (6), and the first spring (9) is connected to the bottom plate of the mounting frame (10).

8. The device for resource utilization of tail gas in the densification process of carbon / carbon composite material according to claim 3, characterized in that, A heat conducting plate (15) is arranged on the side wall of the primary combustion chamber (20), and the outside of the heat conducting plate (15) is covered by a heat conducting channel (18). A hot gas outlet (5) is formed in the side wall of the secondary combustion chamber (21), and the hot gas outlet (5) is communicated with the heat conducting channel (18). The upper end of the heat conducting channel (18) is communicated with the heat conducting pipe (4).

9. The equipment for resource utilization of the tail gas in the densification process of carbon / carbon composite materials according to claim 8, characterized in that, The heat conducting channel (18) is composed of a heat insulation frame and the side walls of the primary combustion chamber (20) and the secondary combustion chamber (21). The heat conducting plate (15) is arranged through the primary combustion chamber (20). The hot gas outlet (5) is of an inclined opening structure.

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