Fluidized bed plasma furnace for continuously preparing carbon nanotubes and carbon nanotube preparation system

Abstract

The utility model discloses a fluidized bed plasma furnace for continuously preparing carbon nanotubes and a carbon nanotube preparation system, which comprise a fluidized bed plasma generator, the fluidized bed plasma generator comprises an anode internally provided with a longitudinal hollow cavity, an air inlet channel communicated with a lower port of the hollow cavity of the anode and a catalyst feeding port communicated with one side of an upper port of the hollow cavity of the anode, and the upper portion and the lower portion of the hollow cavity of the anode are communicated so that a catalyst powder slow sinking area can be formed in the hollow cavity of the anode. Compared with a crucible bearing catalyst (a carbon source and the catalyst in the crucible are subjected to chemical vapor deposition to form a carbon nano tube) in the prior art, on one hand, impurities introduced by using the crucible can be effectively avoided, the purity of the carbon nano tube is improved, and the defects of the carbon nano tube caused by the impurities are reduced; and the catalyst in the fluidized bed can be fully contacted with other materials and is more uniformly heated, so that the quality of the obtained product is more consistent.

Description

TECHNICAL FIELD

[0001] The utility model belongs to carbon nanotube preparation field, concretely relates to a fluidized bed plasma furnace for continuous preparation of carbon nanotube and carbon nanotube preparation system. BACKGROUND

[0002] Carbon nanotubes (CNTs) are widely used in high-performance material fields such as field emission displays, lithium ion batteries, sensors, etc. due to their high crystallinity, good electrical conductivity, and excellent mechanical, electrical, thermal, and chemical properties. For example, carbon nanotubes are used in field emission displays to achieve high brightness and low power consumption due to their extremely low field emission threshold and high emission current density. The high electrical conductivity and high specific surface area of carbon nanotubes can improve the electrical conductivity and energy density of lithium ion batteries, and as an additive to composite electrode materials, they can significantly enhance the cycle stability and rate performance of the battery.

[0003] Common methods for preparing carbon nanotubes (CNTs) include arc discharge, laser ablation, and chemical vapor deposition (CVD), among others. Arc discharge has the advantages of high crystallinity and few structural defects, but has the disadvantage of difficult size control. Laser ablation has good structural uniformity and high crystallinity, but is expensive, has high production costs, and has low production, making it unsuitable for large-scale production. CVD can be performed at relatively low temperatures (typically 500-1000°C), allowing precise control of the length, diameter, and arrangement of carbon nanotubes, making it suitable for large-scale production. However, it requires precise control of the gas flow and catalyst, and the generated carbon nanotubes may have a small amount of structural defects.

[0004] Arc discharge primarily generates plasma through ionized gas, which has high temperature and high enthalpy (temperature > 10000K), and has many active particles (such as electrons and ions). High temperature can accelerate the decomposition of organic matter to generate free radicals, which is important for the growth of carbon nanotubes. Arc discharge includes transfer arc discharge and non-transfer arc discharge. Existing carbon nanotube preparation technology uses transfer arc discharge. For example, patent US20120195820A1 discloses a system and method for preparing carbon nanotubes, and specifically discloses a system and method for preparing carbon nanotubes using a transfer arc fixed bed. However, this system and method have the following problems: on the one hand, unstable transfer arc discharge can lead to a lack of uniformity in the temperature of the reaction system during carbon nanotube preparation, resulting in low-quality carbon nanotubes. On the other hand, the fixed bed bearing method can lead to insufficient contact between the catalyst and the carbon source, and can further exacerbate the uneven heating of the reaction system, which can further reduce the quality of the generated carbon nanotubes. SUMMARY

[0005] The utility model discloses to the technical problem of the carbon nanotube quality not being high of the carbon nanotube generated by the way of the fixed bed preparation carbon nanotube of the existing carbon nanotube preparation system, provide a kind of fluidized bed plasma furnace for continuous preparation carbon nanotube.

[0006] The utility model discloses a fluidized bed plasma furnace for continuous preparation carbon nanotube includes fluidized bed plasma generator, the fluidized bed plasma generator includes:

[0007] Anode, inside with longitudinal hollow cavity;

[0008] Gas inlet passage, with the lower port of the hollow cavity of the anode communication;

[0009] Catalyst feed port, with the upper port of the hollow cavity of the anode one side communication, so that the hollow cavity of the anode forms catalyst powder slow settling area.

[0010] Preferably, the fluidized bed plasma generator further includes:

[0011] Cathode assembly, the cathode assembly has cathode stick, the cathode stick is worn in the hollow cavity of the anode.

[0012] Preferably, the fluidized bed plasma furnace includes catalyst spiral feed bin, is arranged above the fluidized bed plasma generator, the bin bottom of the catalyst spiral feed bin is communicated with the catalyst feed port;Preferably, the bin bottom of the catalyst spiral feed bin is provided with the screw rod type structure that can spiral feed.

[0013] Preferably, the fluidized bed plasma furnace further includes:

[0014] Carrier gas inlet and carbon source inlet are arranged respectively at the bottom of the fluidized bed plasma furnace, and the inlet of the gas inlet passage is communicated;Preferably, the gas distribution ring is further arranged in the gas passage, and the working gas entered by the carrier gas inlet and the carbon source gas entered by the carbon source inlet are mixed uniformly and sent into the catalyst powder slow settling area by the gas distribution ring;

[0015] Material outlet is arranged respectively at the top of the fluidized bed plasma furnace, and the other side of the upper port of the hollow cavity of the anode is communicated.

[0016] Preferably, the cathode assembly further includes:

[0017] Rotary drive mechanism, directly or indirectly connected with the cathode stick, drives the cathode stick to rotate in the hollow cavity of the anode;

[0018] A cathode water cooling jacket, a lower end of which is fixedly connected with the cathode rod, the rotating driving mechanism is drivingly connected with an upper section of the cathode water cooling jacket, preferably the rotating driving mechanism is drivingly connected with the upper section of the cathode water cooling jacket by means of a gear assembly, more preferably a driving gear disc is arranged on a shaft of the rotating driving mechanism, and a driven gear disc is arranged on the cathode water cooling jacket, and the driving gear disc is meshingly connected with the driven gear disc.

[0019] Preferably, the cathode water cooling jacket comprises:

[0020] A water cooling outer tube, a first end of which is fixedly connected with one end of the cathode rod, and the driving mechanism is drivingly connected with the water cooling outer tube through the gear assembly so as to drive the cathode rod to rotate;

[0021] A water cooling inner tube, which is arranged in the water cooling outer tube so that a cold water circulation passage is formed between an inner cavity of the water cooling inner tube and an inner cavity of the water cooling outer tube;

[0022] A cathode mounting seat arranged on one end surface of the plasma generator, and the cathode water cooling jacket is arranged in the cathode mounting seat so that the cathode rod is indirectly mounted on the cathode mounting seat.

[0023] Preferably, the gear assembly comprises:

[0024] A driving gear disc, which is fixedly sleeved on a shaft of the driving mechanism;

[0025] A driven gear disc, which is fixedly sleeved on the water cooling outer tube, and the driven gear disc is meshingly connected with the driving gear disc; preferably the driven gear disc is fixedly sleeved on the water cooling outer tube by means of coaxial interference fit of a gear positioning ring and a gear locking nut.

[0026] Preferably,

[0027] The first end of the water cooling outer tube is a closed end, and an outer side of the closed end of the water cooling outer tube is fixedly connected with one end of the cathode rod;

[0028] The first end of the water cooling inner tube is an open end, and there is a certain spacing between the open end of the water cooling inner tube and the closed end of the water cooling outer tube, so that a cold water circulation passage is formed between the inner cavity of the water cooling inner tube and the inner cavity of the water cooling outer tube;

[0029] Preferably, the cathode water cooling jacket further comprises:

[0030] a water inlet, in communication with the inner cavity of the water-cooled inner tube; preferably, the water-cooled inner tube is provided with a water passage ring, one end of the water passage ring is in communication with the water inlet, the other end of the water passage ring is in communication with the inner cavity of the water-cooled inner tube, more preferably, the water-cooled inner tube has a plurality of tube holes on the tube wall, the water passage ring has a plurality of ring holes in communication with the corresponding tube holes;

[0031] a water outlet, in communication with the inner cavity of the water-cooled outer tube.

[0032] Preferably, the cathode assembly further comprises a magnetic fluid seal, the magnetic fluid seal has:

[0033] a hollow magnetic fluid coaxially sleeved outside the water-cooled outer tube;

[0034] a hollow insulating seat coaxially sleeved outside the water-cooled outer tube, so that the magnetic fluid and the cathode water-cooled sleeve are isolated from the cathode mounting seat; preferably, the insulating seat is a boss-type insulating seat, the thick section of the boss-type insulating seat separates the first end of the magnetic fluid from the cathode mounting seat, and the thin section of the insulating seat separates the water-cooled outer tube of the cathode water-cooled sleeve from the cathode mounting seat;

[0035] a hollow magnetic fluid cover coaxially sleeved outside the water-cooled outer tube and arranged at the second end of the magnetic fluid; preferably, the magnetic fluid cover is arranged at the second end of the magnetic fluid by bolt fastening;

[0036] Preferably, the magnetic fluid seal further has a plurality of insulating pads arranged at the second end of the magnetic fluid;

[0037] Preferably, the gear positioning ring and the gear lock nut for the indirectly connected driven gear disc of the driving mechanism are coaxially fixedly sleeved on the water-cooled outer tube of the cathode water-cooled sleeve, and the gear positioning ring is mounted on the magnetic fluid cover.

[0038] Preferably, the cathode assembly further comprises a shaft end seal, a sealing cover is arranged at the second end of the cathode water-cooled sleeve, and the shaft end seal comprises:

[0039] a hollow sealing seat sleeved outside the second end of the cathode water-cooled sleeve;

[0040] two first shaft sealing rings spaced apart and arranged in parallel, tightly sleeved outside the second end of the water-cooled outer tube and tightly fitted into the first end of the sealing seat;

[0041] at least one second shaft sealing ring tightly sleeved outside the second end of the water-cooled inner tube and tightly fitted into the second end of the sealing seat;

[0042] at least one third shaft sealing ring tightly sleeved outside the second end of the water-cooled inner tube and tightly fitted into the sealing seat;

[0043] The second end of the water-cooled inner tube is sleeved with a water passage ring in communication with the water inlet nozzle, which is arranged in the sealing seat and between the second shaft sealing ring and the third sealing ring.

[0044] Preferably, the hollow interior of the sealing seat has a first step, a second step and a third step at the first end, and a fourth step at the second end;

[0045] The end of the second end of the water-cooled outer tube is inserted into the cavity formed by the first step of the first end of the sealing seat;

[0046] The first shaft sealing ring is tightly sleeved outside the second end of the water-cooled outer tube and tightly pressed against the second step of the first end of the sealing seat and the inner wall of the cavity formed by the second step;

[0047] The shaft end sealing member further comprises a hollow first shaft sealing gland, which is sleeved on the second end of the water-cooled outer tube and covers the first shaft sealing ring on one side of the cavity formed by the third step of the first end of the sealing seat;

[0048] The second shaft sealing ring is tightly sleeved outside the second end of the water-cooled inner tube and tightly pressed against the fourth step of the second end of the sealing seat and the inner wall of the cavity formed by the fourth step;

[0049] The shaft end sealing member further comprises a second shaft sealing gland, the outer edge of the first side surface of which is fixed, preferably by bolts, to the side surface of the second end of the sealing seat, and the first side surface of the second shaft sealing gland covers the second shaft sealing ring;

[0050] Preferably, the rotary drive mechanism further comprises:

[0051] A drive mounting seat is fixedly arranged on one side of the sealing seat, and a drive motor is mounted on the drive mounting seat;

[0052] A bearing is arranged in the cavity formed by the third step of the first end of the sealing seat, so that the drive motor of the drive mechanism drives the water-cooled outer tube of the cathode water-cooled jacket to rotate while the sealing seat and the water-cooled inner tube of the cathode water-cooled jacket do not rotate, preferably, the bearing is located on one side of the first shaft sealing gland.

[0053] Preferably,

[0054] The second shaft sealing gland is a hollow second shaft sealing gland, which is sleeved on the second end of the water-cooled inner tube;

[0055] The shaft end sealing member further comprises:

[0056] A hollow small shaft positioning cover is arranged on the second side of the second shaft seal cover, and is fixed on the side of the second end of the sealing seat by bolts;

[0057] A solid small shaft is arranged in the small shaft positioning cover through a pressing ring gasket on the second end surface of the small shaft positioning cover, and the first end of the small shaft is fixedly connected with the end surface of the second end of the water-cooled inner tube through a reverse opening groove welding, so that the water-cooled inner tube is fixed.

[0058] Preferably, the cathode assembly further comprises:

[0059] A brush assembly is arranged on one side of the sealing seat, preferably, two ends are provided with insulating pads, and a cathode lug is fixedly connected with the shell of the brush assembly.

[0060] Another purpose of the utility model is to provide a carbon nanotube preparation system, comprising:

[0061] The fluidized bed plasma furnace;

[0062] The condenser has a condenser inlet and a condenser outlet, and the condenser inlet is communicated with the material outlet of the non-transferred arc plasma furnace;

[0063] The collecting device for collecting the condensed product has a collecting inlet and a collecting outlet, and the collecting inlet is communicated with the condenser outlet;

[0064] The air induction system has an air inlet and an air outlet, and the air inlet is communicated with the collecting outlet.

[0065] The utility model has the following beneficial effects:

[0066] 1) the catalyst provided by the utility model is introduced into the hollow cavity of the anode from top to bottom in the reaction process, and the upward airflow prevents the catalyst powder from falling down, so that the hollow cavity of the anode forms a slow settling area of the catalyst powder, and the catalyst (carbon source and catalyst in the crucible are subjected to chemical vapor deposition to form carbon nanotubes) in the crucible in the prior art is not needed, therefore, impurities introduced due to the use of the crucible can be effectively avoided, the purity of the carbon nanotubes is improved, and carbon nanotube defects caused by impurities are reduced.

[0067] 2) the method of the utility model can also adjust the reaction temperature and the catalyst feeding rate of the non-transferred arc discharge area through the airflow and the current for generating the non-transferred arc, and further control the morphology and size of the generated carbon nanotubes.

[0068] 3) The cathode rod is coaxially arranged in the anode, so that an annular non-transferred arc discharge area is formed between the cathode rod and the anode. Compared with the transferred arc discharge, the non-transferred arc discharge is more stable, the temperature of the non-transferred arc discharge area is more uniform, and a larger high-temperature area is provided. In addition, the catalyst in the utility model does not need a catalyst carrier, so that impurities of the catalyst carrier introduced in the reaction process can be effectively avoided, and the generated carbon nanotube impurities are less.

[0069] 4) The plasma furnace provided by the utility model is a fluidized bed relative to the catalyst. Compared with a fixed bed, the catalyst in the fluidized bed can be in full contact with other materials and is heated more uniformly, so that the product quality is more consistent, and the carbon nanotube prepared by the fluidized bed has a smaller diameter, so as to facilitate the application in the downstream.

[0070] 5) The equipment adopted by the utility model has a lower production cost, is suitable for large-scale production, and is relatively compact, so that the equipment is suitable for process amplification and optimization.

[0071] 6) A rotating driving motor is arranged on the cathode rod, and the cathode rod can be driven to rotate in the discharge process, so that the cathode rod ablation is more uniform, the high-temperature area distribution is more uniform, and the local ablation pit and local ablation less situation can be effectively avoided.

[0072] 7) The length of the high-temperature area of the plasma generated in the plasma furnace can be accurately controlled by adjusting the length of the cathode rod electrode, the high-temperature area is concentrated and uniform, the carbon source gas cracking and the carbon nanotube growth rate and quality are improved, and the production efficiency is higher.

[0073] 8) The cathode water cooling jacket adopts annular cooling, so that the cathode assembly can be fully heat-exchanged and cooled while the sealing is ensured.

[0074] 9) In order to enhance the sealing property of the hollow cavity of the anode, the magnetic fluid is used for sealing at the cathode mounting seat of the cathode assembly, and the water cooling system of the cathode assembly is also sealed. BRIEF DESCRIPTION OF DRAWINGS

[0075] Figure 1 It is a system schematic view of the non-transferred arc fluidized bed continuous preparation of carbon nanotubes of the utility model;

[0076] Figure 2A It is a structure schematic view of the cathode assembly of the non-transferred arc fluidized bed continuous preparation of carbon nanotubes of the utility model;

[0077] Figure 2B It is Figure 2A the local enlarged schematic view of the shaft end sealing element of the cathode assembly;

[0078] Figure 2C It isFigure 2A Partial enlarged view of magnetic fluid seal of cathode assembly of the utility model;

[0079] Figure 3 Sectional view of cathode mounting seat of cathode assembly of the utility model;

[0080] Figure 4 Sectional view of magnetic fluid insulation seat of cathode assembly of the utility model;

[0081] Figure 5 Sectional view of magnetic fluid cover of cathode assembly of the utility model;

[0082] Figure 6A Isometric side view of sealing seat of cathode assembly of the utility model;

[0083] Figure 6B Sectional view of Figure 6A ;

[0084] Figure 7A Structure schematic view of water passage ring of cathode assembly of the utility model;

[0085] Figure 7B Sectional view of water passage ring of Figure 7A ;

[0086] Figure 8A Structure schematic view of small shaft positioning cover of cathode assembly of the utility model;

[0087] Figure 8B Top view of small shaft positioning cover of Figure 8A ;

[0088] Figure 8C Sectional view of small shaft positioning cover of Figure 8A ;

[0089] Figure 9A Structure schematic view of catalyst screw feeding bin with stirring of the utility model;

[0090] Figure 9B Sectional view of catalyst screw feeding bin of Figure 9A ;

[0091] Figure 9C Structure schematic view of another catalyst screw feeding bin without stirring of the utility model;

[0092] Figure 9D Sectional view of catalyst screw feeding bin of Figure 9C ;

[0093] Figure 10A Structure schematic view of cyclone collector of the utility model;

[0094] Figure 10B FIG. 2 is a cross-sectional view of a cyclone collector according to the present application; Figure 10A

[0095] Figure 11 FIG. 6 is a schematic diagram of a gas distribution ring structure according to the present application;

[0096] Figure 12 FIG. 9 is a schematic diagram of a Raman diffraction detection result of single-walled carbon nanotubes prepared in Example 1 according to the present application;

[0097] Figure 13 FIG. 11 is a schematic diagram of a prior art carbon nanotube preparation system according to the present application. DETAILED DESCRIPTION

[0098] The embodiments of the present application will be described in detail with specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the specification. The present application can also be implemented or applied through specific embodiments, and each detail in the specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present application.

[0099] It should be noted that, in the present application, up, down, left and right are set for convenience of description, and the directions are based on the numbers or words in the drawings, with the upper part of the numbers being up and the lower part of the numbers being down, and the like. Non-transferred arc plasma generator, plasma generator and non-transferred arc fluidized bed plasma generator all refer to devices capable of generating plasma.

[0100] As Figure 1 ​​As shown, the non-transferred arc fluidized bed continuous preparation system of carbon nanotubes of the utility model has a plasma furnace 1, a condenser 2, a collecting device 3 and an air induction system 4, wherein the condenser 2 has a condenser feed inlet and a condenser discharge outlet, and the collecting device 3 has a collecting feed inlet and a collecting discharge outlet. The condenser 2 and the collecting device 3 are of a conventional structure, as long as they can play a role of cooling and collecting carbon nanotubes, for example, the condenser 2 can be of a water cooling structure, or can be the carbon nanotube powder material intermediate transfer cooling device disclosed in CN220892639U. The collecting device 3 can be a cyclone collector or a cloth bag collector, and is generally of a stainless steel cylindrical tank structure. The air induction system 4 also has an air inlet and an air outlet. The condenser feed inlet of the condenser 2 is communicated with the material outlet 16 of the non-transferred arc fluidized bed plasma furnace 1, and the condenser discharge outlet of the condenser 2 is communicated with the collecting feed inlet of the collecting device 3, and the collecting discharge outlet of the collecting device 3 is also communicated with the air inlet of the air induction system 4, that is, the carbon nanotubes generated in the non-transferred arc fluidized bed plasma furnace 1 are first discharged from the carbon nanotube and tail gas material outlet 16 of the non-transferred arc fluidized bed plasma furnace 1, then cooled by the condenser 2, collected by the collecting device 3, and the tail gas is continuously discharged to the outside through the air outlet of the air induction system 4, and then discharged into the atmosphere after reaching the recycling system or reaching the emission standard. And the condenser 2 is a sealed container, and the condenser 2 has water or a water solution containing a surfactant in the condenser tube, which is to quickly cool the passing carbon nanotubes.

[0101] In one example, the collecting device 3 adopts a cyclone collector, as shown in Figure 10A and Figure 10B , which is of a stainless steel structure, and the internal structure can produce a spiral flow effect, and the tail gas and carbon nanotubes in the material outlet 16 can be helically settled or spirally coiled in the cyclone collector, and then collected by the collecting tank at the bottom of the collecting device 3, and the tail gas is discharged from the discharge outlet of the collecting device 3. Compared with the traditional cloth bag collector, the cyclone collector can collect more carbon nanotubes, and can also separate and collect products of different particle sizes. In addition, the air volume of the air induction system 4 can be adjusted and controlled, which can not only discharge the waste gas generated in the system, but also further effectively prevent or reduce the carbon nanotube product from being sucked out. The above air induction system can select the air induction fan produced by Chengdu Jiangbei General Mechanical Manufacturing Co., Ltd., which has a maximum air induction volume of 1659m 3 / h, and the model is 4-72-28, or can also select the 2BV-6110 water ring vacuum pump produced by Sichuan Huaxin Nanjing Vacuum Equipment Co., Ltd.

[0102] In the example, as shown in Figure 1As shown in the figure, the plasma furnace 1 for carbon nanotube preparation comprises, from inside to outside, a plasma generator, a heat preservation layer 13 and an outer shell 14, that is, the plasma generator is arranged in the heat preservation layer 13, and the heat preservation layer 13 is arranged in the outer shell 14. The heat preservation layer 13 is made of high-temperature-resistant material, in this example, zirconia corundum, alumina hollow ball sintering preform and glass fiber filling body, and the outer shell 14 adopts a double-layer water-cooling stainless steel coil pipe structure to prevent the outer part of the furnace body from overheating.

[0103] Continuing as Figure 1 As shown in the figure, the plasma generator comprises an anode 11 and a cathode assembly 12, wherein the cathode assembly 12 has a cathode rod 121. The anode 11 has a cylindrical longitudinal hollow cavity inside, and the cathode rod 121 is coaxially arranged in the cylindrical hollow cavity of the anode 11 and spaced apart from the anode 11. The cathode rod 121 is made of high-temperature-resistant graphite, and has a solid cylindrical structure with a diameter of 60mm-100mm and a length of 400mm-1200mm. The material of the anode 11 can be high-temperature-resistant graphite, or can be a high-temperature-resistant alloy material composed of refractory metal and metal with catalytic effect, wherein the refractory metal can be selected from one or more of tungsten, molybdenum and tantalum, and the metal with catalytic effect can be selected from one or more of iron, cobalt and nickel, which can further improve the catalytic reaction efficiency. The inner diameter of the anode 11 is 65mm-120mm, the length is 400mm-1250mm, and the wall thickness of the single side of the anode 11 is 80mm-150mm, preferably 100mm-120mm. The hollow cavity of the anode 11 is sequentially divided into a cylindrical non-reaction cavity section and a reaction cavity section from top to bottom, and the cathode rod 121 coaxially arranged in the hollow cavity is also correspondingly divided into a non-reaction rod section and a reaction rod section from top to bottom. In this example, continuing as Figure 1 As shown in the figure, the inner wall of the non-reaction cavity section of the hollow cavity and the non-reaction rod section of the cathode rod 121 arranged in the non-reaction cavity section form an annular reaction auxiliary ring cavity 111, wherein one side of the annular reaction auxiliary ring cavity 111 is communicated with the catalyst inlet 15, and the other side is communicated with the material outlet 16, that is, the catalyst first passes through the catalyst inlet 15 on one side of the reaction auxiliary ring cavity 111, then passes through the reaction auxiliary ring cavity 111, and finally enters the reaction cavity section of the anode 11. The generated carbon nanotubes are discharged upward through the material outlet 16 on the other side of the reaction auxiliary ring cavity 111, and finally condensed by the condenser 2 and collected by the collecting device 3. In the present application, since the density of the catalyst is greater than that of the carbon nanotubes, the catalyst can be made to move from top to bottom by controlling the gas flow speed, the generated carbon nanotubes can be made to move from bottom to top, and the carbon nanotubes can be made to leave the plasma furnace 1 from the material outlet 16 located at the upper part of the plasma furnace 1.

[0104] Similarly, the inner wall of the reaction cavity section below the non-reaction cavity section of the hollow cavity and the reaction rod section of the cathode rod 121 coaxially arranged in the reaction cavity section form a non-transferred arc discharge zone, i.e., a non-transferred arc discharge annular cavity 112. The non-transferred arc discharge annular cavity 112 is the core reaction zone for the non-transferred arc ionization for preparing carbon nanotubes, and the catalyst enters the non-transferred arc discharge annular cavity 112 from top to bottom to participate in the catalytic ionization reaction. Moreover, the non-transferred arc discharge annular cavity has equal radial spacing at different axial positions, i.e., the spacing between the reaction rod section of the cathode rod 121 and the inner wall of the reaction cavity section 112 of the anode 11 is equal from top to bottom, so that a very stable non-transferred arc can be generated. In addition, as shown in Figure 1 the reaction auxiliary annular cavity 111 formed above the non-transferred arc discharge annular cavity 112 has a cross-sectional shape that is wide at the top and narrow at the bottom, i.e., the radial spacing of the reaction auxiliary annular cavity 111 is greater than that of the non-transferred arc discharge annular cavity 112. Since the radial spacing of the reaction auxiliary annular cavity 111 at the upper segment of the hollow cavity of the anode 11 is larger, the gas flow speed is smaller, and the catalyst feeding is more convenient. At the same time, the generated carbon nanotubes can be better separated from the catalyst in this area, resulting in higher purity of the obtained carbon nanotubes. The smaller radial spacing of the non-transferred arc discharge annular cavity 112 is more conducive to the generation of plasma discharge, and the smaller spacing requires lower specifications for the matching power supply, and the energy consumption required for the reaction process and the cost of manufacturing the plasma furnace 1 are both lower. The radial spacing of the non-transferred arc discharge annular cavity 112 is 2.5 mm to 20 mm, such as 3 mm, 5 mm, 15 mm, 18 mm, etc., and is preferably 8 mm to 13 mm, such as 10 mm, 12 mm, etc. The axial length of the non-transferred arc discharge annular cavity 112 is 200 mm to 1000 mm, such as 300 mm, 400 mm, 800 mm, 900 mm, etc., and is preferably 500 mm to 700 mm.

[0105] In this example, as shown in Figures 9A-9D the catalyst is introduced into the hollow cavity of the anode 11 from top to bottom through the catalyst spiral feed bin 19, while the carrier gas, carbon source gas, and hydrogen gas are introduced into the hollow cavity of the anode 11 from bottom to top. The rising gas can provide a certain buoyancy to the descending catalyst, which forms a catalyst powder slow-settling zone in the hollow cavity of the anode 11, thereby prolonging the time of the catalyst participating in the reaction.

[0106] To increase the reaction time of the catalyst, the catalyst in this invention can be a powdered catalyst, preferably a nano-sized catalyst. The catalyst powder settling zone is composed of the reaction-aiding annular cavity 111 and the non-transfer arc discharge annular cavity 112 within the aforementioned hollow cavity. Furthermore, in this example, the catalyst in the catalyst powder settling zone is in a fluidized state; that is, the plasma furnace 1 provided by this invention is a fluidized bed. Compared to the fixed bed in the prior art, such as... Figure 13 As shown, the catalyst is loaded into a crucible to participate in the reaction. The catalyst in the fluidized bed can fully contact other reactants, such as carbon sources, and is heated more uniformly. Simultaneously, the solid catalyst does not use other supports, such as crucibles, which minimizes the quantity and types of impurities introduced into the reaction system and further effectively promotes the formation of high-quality carbon nanotubes from the carbon source, resulting in more consistent product quality. Therefore, further, in this example, the plasma generator includes an anode 11, an inlet channel 131, a catalyst inlet 15, and a cathode assembly 12. The plasma furnace includes a plasma generator, a catalyst spiral feed chamber 19, a material outlet 16, a carrier gas inlet 17, and a carbon source inlet 18. In addition, in this example, continuing as... Figure 9A and Figure 9B As shown, to facilitate better catalyst feeding, a stirring device is also provided at the upper end of the catalyst screw feed hopper 19. Alternatively, a stirring device can be directly installed... Figure 9C and Figure 9D The catalyst spiral feed bin shown.

[0107] In other examples, continue as follows Figures 2A-3 As shown, the cathode assembly 12, such as a spin cathode assembly, includes, in addition to the cathode rod 121, a cathode mounting base 122 for mounting and fixing the entire cathode assembly 12, a cathode water-cooling jacket 123 for cooling the cathode rod and preventing excessive heat conduction, a magnetohydrodynamic seal 124 for sealing the cathode mounting base 122 and mounting the cathode water-cooling jacket 123, a shaft end seal 125 for sealing the cathode water-cooling jacket 123, and a rotary drive mechanism 126 for driving the cathode rod 121 to rotate and discharge. The cathode mounting base 122 is a raised hollow flange structure, fixedly mounted on the upper end face of the outer casing 14. Its flange face has several through holes, threaded holes, and sealing grooves for mounting the cathode water-cooling jacket 123. The cathode water-cooling jacket 123 passes through the cathode mounting base 122, and its first end is threadedly connected to one end of the cathode rod 121, indirectly allowing the cathode rod 121 to also be mounted on the cathode mounting base 122.

[0108] In other examples, such as Figure 2B , Figure 6A , Figure 6BAs shown, the cathode water cooling jacket 123 includes a water cooling inner tube 1231, a water cooling outer tube 1232, a water inlet 1233, a water outlet 1234 and a water circulation ring 1235. The water cooling inner tube 1231 is a hollow tubular structure of 304 stainless steel material with open ends, with a wall thickness of 1.5mm-2.5mm, and the water cooling outer tube 1232 is a hollow tubular structure with one open end and one closed end, and the water cooling inner tube 1231 is arranged in the water cooling outer tube 1232. The water cooling inner tube 1231 and the water cooling outer tube 1232 both include a first end and a second end, wherein the first end of the water cooling inner tube 1231 is an open end, and the first end of the water cooling outer tube 1232 is a closed end, and the end face of the closed end of the water cooling outer tube 1232 is inwardly recessed and has an internal thread, and the end face of the cathode rod 121 connected to the end face of the closed end of the water cooling outer tube 1232 is inwardly convex and has an external thread, and the internal and external threads of the two end faces make the cathode rod 121 tightly connected to the first end of the water cooling outer tube 1232. In addition, the open end of the water cooling inner tube 1231 and the closed end of the water cooling outer tube 1232 have a certain spacing, so that the inner cavity of the water cooling inner tube 1231 and the inner cavity of the water cooling outer tube 1232 form a continuous cold water circulation passage. At the same time, a water inlet 1233 is arranged at the second end of the water cooling inner tube 1231, which is in communication with the inner cavity of the water cooling inner tube 1231, and a water outlet 1234 is arranged at a position slightly lower than the height of the water inlet 1233, which is in communication with the inner cavity of the water cooling outer tube 1232, so that the cooling water first enters the water cooling inner tube 1231 through the water inlet 1233, then flows through the cold water circulation passage to the water cooling outer tube 1232, and cools the discharge heating cathode rod 121 connected to the lower end of the water cooling outer tube 1232, and finally flows out from the water outlet 1234 connected to the water cooling outer tube 1232, which can further prevent the heat from being conducted to the outside to cause damage to other components or affect their use efficiency. Of course, in order to uniformly distribute the water in the flow channel without forming an air zone, the cooling effect is improved.

[0109] As Figure 7A and Figure 7BAs shown, the sealing seat for sealing the cathode water cooling jacket is provided with a water passing gap outside the second end of the water cooling inner tube 1231, and the water passing ring 1235 is sleeved outside the second end of the water cooling inner tube 1231 and clamped at the water passing gap of the sealing seat, one end of the water passing ring 1235 is communicated with the water inlet nozzle 1233, and the other end is communicated with the inner cavity of the water cooling inner tube 1231. Specifically, the water passing ring 1235 is a hollow cylinder as a whole, and a plurality of ring holes are arranged on the annular circumferential surface thereof, and the water cooling inner tube 1231 is further provided with a plurality of pipe holes corresponding to the ring holes on the pipe wall of the circumferential surface of the water cooling inner tube 1231 sleeved with the water passing ring 1235, the diameter of the pipe holes is 6mm-10mm, and the number is 4-8. That is, the cooling water enters through the ring holes on the water passing ring 1235 after entering through the water inlet nozzle 1233, and then flows into the water cooling inner tube 1231, and then flows out through the water outlet nozzle 1234 through the cold water circulation passage between the water cooling outer tube 1232 and the water cooling inner tube 1231 to achieve the circulation cooling effect.

[0110] In other examples, as shown in Figure 2C , Figure 4 and Figure 5 , the magnetic fluid sealing element 124 and the shaft end sealing element 125 are respectively sealingly arranged at the outer periphery of the middle and lower segments of the water cooling outer tube 1232 and the second end of the cathode water cooling jacket 123, that is, the upper segments and top ends of the water cooling inner tube 1231 and the water cooling outer tube 1232. The magnetic fluid sealing element 124 includes a hollow magnetic fluid 1241, a hollow insulation seat 1242, a hollow magnetic fluid cover 1243, and a plurality of insulation pads 1244, and the magnetic fluid 1241 and the insulation seat 1242 are coaxially sleeved outside the water cooling outer tube 1232. The magnetic fluid 1241 can be directly used in the standard dynamic sealing structure on the market, and the insulation seat 1242 is a hollow boss cylindrical structure, which is made of polytetrafluoroethylene or other insulation materials with good insulation performance. The insulation seat 1242 plays a sealing role on the one hand, and isolates the external air from the plasma furnace 1, and on the other hand, also plays an insulation effect, avoids the conduction of the current generated by the plasma generator to the outside of the plasma furnace 1, and plays a role in preventing the staff from being electrocuted. The insulation seat 1242 is also coaxially installed in the cathode mounting seat 122, that is, the coaxially installed insulation seat 1242 simultaneously isolates the magnetic fluid 1241 and the water cooling outer tube 1232 from the cathode mounting seat 122. Continue as Figure 4As shown, the boss cylindrical insulation seat 1242 has a thick section and a thin section, the thick section of the boss insulation seat separates the first end of the magnetic fluid 1241 from the cathode mounting seat 122, and the thin section of the boss insulation seat separates the water-cooled outer tube 1232 of the cathode water-cooled jacket 123 from the cathode mounting seat 122, to avoid short circuit between the two electrodes, and at the same time to accurately position the cathode rod 121 after placement to ensure that the gap between the cathode rod 121 and the anode 11 forms a uniform non-transferred arc discharge ring cavity 112. At the same time, through bolts, the cathode mounting seat 122, the insulation seat 1242 and the magnetic fluid 1241 are coaxially sleeved on the water-cooled outer tube 1232. In addition, at the second end of the magnetic fluid 1241, an insulation pad 1244 and a magnetic fluid cover 1243 are sequentially arranged, wherein the insulation pad 1244 is made of polytetrafluoroethylene or other materials with insulation properties, and the magnetic fluid cover 1243 is a hollow recessed boss structure made of 304 stainless steel, coaxially sleeved outside the water-cooled outer tube 1232, and one of the recessed boss structures is fastened by bolts at the second end of the magnetic fluid 1241 to protect the magnetic fluid 1241, and the other side is provided with a number of countersunk holes made of 304 stainless steel matched with the fixing bolts. And continue as Figure 2B 、 Figure 6A and Figure 6BAs shown, the second end of the cathode water cooling jacket 123 is provided with an end seal 125, which comprises a seal seat 1251, at least one first shaft seal ring 1252, at least one second shaft seal ring 1253, at least one third shaft seal ring 1254, a first shaft seal cover 1255, a second shaft seal cover 1256, a hollow small shaft positioning cover 1257 and a solid fixed small shaft 1258. The seal seat 1251 is a hollow circular truncated cone structure made of 304 stainless steel, which is sleeved outside the second end of the cathode water cooling jacket 123. The circular truncated cone surface of the seal seat 1251 is provided with a plurality of bolt hole positions and a plurality of threaded holes for mounting the driving mounting plate 1261 and the bearing cover; the circumferential surface of the seal seat 1251 is also provided with cooling water inlet and outlet holes, which are integrally welded with the water inlet nozzle 1233 and the water outlet nozzle 1234, respectively. In order to fully guarantee the sealing effect of the cathode water cooling jacket 123 sleeved by the seal seat 1251, the hollow interior of the seal seat 1251 has a first inwardly recessed step, a second step and a third step at the first end, and a fourth inwardly recessed step at the second end. The second end of the water cooling outer pipe 1232 is inserted into the cavity formed by the first step at the first end of the seal seat 1251; the first shaft seal ring 1253 is tightly sleeved outside the second end of the water cooling outer pipe 1232 and tightly pressed against the second step at the first end of the seal seat 1251 and the inner wall of the cavity formed by the second step to guarantee the sealing of the second end of the water cooling outer pipe 1232. The first shaft seal cover 1255 is sleeved on the second end of the water cooling outer pipe 1232 and is located in the cavity formed by the third step at the first end of the seal seat 1251 and tightly covers one side of the first shaft seal ring 1252 to limit and press the first shaft seal ring 1252, so that the first shaft seal ring 1252 maintains the inwardly shrinking pressure to realize sealing. The second shaft seal ring 1253 and the third shaft seal ring 1254 are both tightly sleeved outside the second end of the water cooling inner pipe 1231 and are located at both ends of the water passage ring 1235 of the cathode water cooling jacket 123. That is, the water passage ring 1235 is installed in the seal seat 1251 and is located between the second shaft seal ring 1253 and the third shaft seal ring 1254, which can guarantee the sealing performance of the cooling water passing through the water passage ring 1235. The second shaft seal ring 1253 is also tightly pressed against the fourth step at the second end of the seal seat 1251 and the inner wall of the cavity formed by the fourth step. In order to press and tightly press the second shaft seal ring 1253 in the fourth step cavity of the seal seat 1251, the first side of the second shaft seal cover 1256 tightly covers the second shaft seal ring 1253, and the second shaft seal cover 1256 is a hollow cylindrical boss structure made of 304 stainless steel, which is provided with a plurality of bolt holes at the outer edge of the flat surface, and the boss surface is used to press the second shaft seal ring 1253. At the same time, the first side of the second shaft seal cover 1256 is provided with bolt holes at the outer edge, which can be directly fixed to the side of the second end of the seal seat 1251 by bolts. The third shaft seal ring 1254 is installed below the water passage ring 1235 and tightly pressed in the seal seat 1251.

[0111] In addition, in the present example, as shown in Figures 8A-8C the second end of the seal seat 1251 is provided with a threaded hole, and the shaft positioning cover 1257 and the second shaft seal cover 1256 are fixed to the side of the second end of the seal seat 1251 through the threaded hole and bolts in sequence, wherein the shaft positioning cover 1257 is installed on the second side of the second shaft seal cover 1256. The shaft positioning cover 1257 is also a hollow cylindrical boss structure made of 304 stainless steel, and a plurality of waist-shaped holes are provided on the cylindrical plane, the number of which is 3-6, and the diameter is 6-10 mm, and the inner surface is provided with a key groove mounting hole for positioning installation. The fixed shaft 1258 is a solid cylindrical structure, and a threaded hole is provided at the central axis of one end face, and the fixed shaft 1258 is fixed in the shaft positioning cover 1257 through the bolt and the gasket ring pad provided in the threaded hole and fixed in the second end face of the shaft positioning cover 1257. At the same time, the fixed shaft 1258 is provided with a boss outwardly protruding on the circumferential surface of 2mm close to one end of the water-cooled inner tube 1231, which is used for coaxial installation with the shaft positioning cover 1257. The outer surface of the shaft positioning cover 1257 is also provided with a key groove mounting hole, which coincides with the key groove mounting hole of the fixed shaft, which is used for positioning the water-cooled inner tube 1231 installed at one end of the fixed shaft 1258, and at the same time, the key groove mounting hole is used to effectively prevent the fixed shaft 1258 from rotating. At the same time, a reverse mouth groove is also provided at the contact between the first end of the fixed shaft 1258 and the end face of the second end of the water-cooled inner tube 1231, and the water-cooled inner tube 1231 is welded and fixed on the fixed shaft 1258 through the reverse mouth groove, so as to realize the fixation of the water-cooled inner tube 1231 without rotating. As shown in Figure 2B In the present example, the above-mentioned first shaft seal ring 1252 is two spaced parallel first shaft seal rings, and the two spaced parallel first shaft seal rings have a shaft seal gasket therebetween. Of course, the above-mentioned second shaft seal ring 1253 and the third shaft seal ring 1254 can also be two spaced parallel second shaft seal rings and third shaft seal rings, and the two spaced second shaft seal rings and the two spaced third shaft seal rings also have corresponding shaft seal gaskets (not shown in the figure). At the same time, the above-mentioned first, second and third shaft seal rings are standard sealing elements, and the materials thereof are nitrile rubber or fluorine rubber. In addition, the above-mentioned first shaft seal cover 1255 and the second shaft seal cover 1256 can be hollow structures.

[0112] In the present example, as shown in Figure 2AAs shown, the water-cooled outer tube 1232 of the cathode water-cooled jacket 123 is also drivingly connected with the rotary driving mechanism 126, and the first end of the water-cooled outer tube 1232 is threadedly fixedly connected with one end of the cathode rod 121, and the rotary driving mechanism 126 is drivingly connected with the water-cooled outer tube 1232 through the gear assembly 127, that is, the rotary driving mechanism 126 indirectly drives the cathode rod 121 to rotate through the gear assembly 127 and the water-cooled outer tube 1232. The rotary driving mechanism 126 further comprises a driving motor, a driving mounting seat 1261, a driven gear positioning ring 1262 and a driven gear locking nut 1263, and the gear assembly 127 comprises a driving gear disc 1271 and a driven gear disc 1272. The driving mounting seat 1261 is a flat plate structure, one side of which is provided with a plurality of bolt holes for mounting the driving motor, and the other side is also provided with a plurality of bolt mounting holes for fixing the driving mounting seat 1261 on the sealing seat 1251 to provide a working platform when the motor rotates. The driving gear disc 1271 is drivingly connected with the rotary driving mechanism 126, that is, the motor shaft of the driving motor of the driving mechanism, that is, the central hole of the driving gear disc 1271 is coaxially mounted with the driving motor mounted on the driving mounting seat 1261 and is connected by bolts. The rotational speed of the driving motor is usually set to 1-20 r / min, and the driven gear disc 1272 is a standard gear structure made of ordinary carbon steel and is installed on the water-cooled outer tube 1232 by interference fit. The driving gear disc 1231 and the driven gear disc 1232 are installed on the same plane, and the driving gear disc 1231 is meshingly connected with the driven gear disc 1232, so that the water-cooled outer tube 1232 is driven by the rotary driving mechanism 126, and the cathode rod 121 is further driven to rotate, so that the cathode rod 121 can discharge more uniformly in the hollow cavity of the anode 11, which is beneficial to the uniform ablation of the graphite cathode rod 121 and improves the uniformity of plasma discharge and temperature, effectively controls the morphology, size and structure of carbon nanotubes, and further avoids the occurrence of local ablation pits and local ablation of the cathode rod 121. At the same time, as shown, the driven gear positioning ring 1262 and the driven gear locking nut 1263 are coaxially fixedly installed on the water-cooled outer tube 1232 by interference fit, and are located at the lower end and the upper end of the driven gear disc 1272, respectively. The driven gear positioning ring 1262 is a hollow cylindrical structure made of 304 stainless steel, and is internally provided with threads and is coaxially fixedly installed on the magnetic fluid cover 1243 of the above-mentioned magnetic fluid seal 124 by threads. The driven gear locking nut 1263 is a hollow circular table structure made of 304 stainless steel, and the inner surface is provided with internal threads and is connected with the water-cooled outer tube 1232 by threads on the driven gear disc 1272, so as to tighten the driven gear disc 1272 and prevent loosening during rotation.

[0113] Continuing as Figure 2A and Figure 2BAs shown, the water-cooling outer tube 1232 will also be driven to rotate by the rotating driving mechanism 126. In order to keep the sealing seat 1251 and the water-cooling inner tube 1231 from rotating, a bearing 1264 of the rotating driving mechanism 126 is arranged in the cavity formed by the third step at the first end of the sealing seat 1251, so that the driving motor of the rotating driving mechanism drives the water-cooling outer tube 1232 to rotate while the sealing seat 1251 and the water-cooling inner tube 1231 do not rotate. In order to further improve the utilization of the space of the device and make the device relatively compact so as to facilitate the scale-up and optimization of the process, the above-mentioned bearing 1264 is directly arranged at the lower part of the first shaft seal cover 1255. In addition, a bearing cover is arranged at one side end of the bearing 1264, which is a 304 stainless steel hollow circular truncated cone structure, and a plurality of bolt mounting holes are arranged on one table surface, which are coaxially connected with the sealing seat 1251 by bolts for fastening the bearing 1264 which is coaxially arranged on the water-cooling outer tube 1232 by interference.

[0114] In addition, an electric brush assembly 128 is arranged at one side end of the above-mentioned magnetic fluid 125, which is a copper electric brush standard part for current transmission, and a cathode lug is arranged at one side end of the electric brush assembly 128, which is integrally welded with the shell of the electric brush assembly 128. A plurality of insulating pads 1244 are arranged between the electric brush assembly 128 and the sealing seat 1251, which can separate the electric brush assembly 128 from the magnetic fluid 125 to achieve electrical insulation between the two, and the material of the insulating pad 1244 is polytetrafluoroethylene or other materials with good insulating properties.

[0115] In addition, as shown in Figure 1 In addition, as shown in Figure 2A and Figure 11As shown, a gas distribution ring 132 is also arranged in the gas inlet channel 131, and the carrier gas inlet and the carbon source gas inlet can be mixed uniformly by the gas distribution ring 132, and then the mixed gas is sent into the hollow cavity of the anode 11, wherein the carrier gas is any one of nitrogen, argon and helium, or a mixture of two or more kinds of gases in any mixing ratio. Figures 9A-9D As shown, a catalyst spiral feeding bin 19 is also arranged in communication above the catalyst feeding port 15, the catalyst spiral feeding bin 19 is a prior art, the catalyst spiral feeding bin 19 is arranged above the hollow cavity of the anode 11, and the bottom of the catalyst spiral feeding bin 19 is in communication with the catalyst feeding port 15, and the bottom of the catalyst spiral feeding bin 19 is provided with a screw rod type structure for spiral feeding, so that the catalyst feeding is more uniform and continuous.

[0116] Continuing as Figure 1 Another purpose of the utility model is to provide a method for continuously preparing carbon nanotubes by a non-transferred arc fluidized bed, which specifically comprises the following steps.

[0117] In step S1, the hollow cavity of the anode of the plasma furnace is first evacuated to a vacuum state, such as 50 kPa, and the catalyst is placed in the catalyst spiral feeding bin 19, wherein the catalyst is selected from one or more combinations of elemental powders of iron, cobalt and nickel, and is ready for use.

[0118] In step S2, a starting flow of inert gas is introduced into the hollow cavity of the anode 11 from the bottom to the top through the carrier gas inlet 17 and the gas inlet channel 131 to form an inert gas atmosphere, preferably, the starting flow of the introduced inert gas is 50 slm~100 slm; at the same time, the starting current is set to open the power supply and adjust the current to the arc ignition success, preferably, the starting current of the plasma is 50A~100A; then the inert gas is adjusted to the working flow and the current of the plasma is adjusted to the working current to heat the plasma furnace; wherein the working flow of the inert gas is 100 slm~500 slm, preferably 300 slm, and the working current of the plasma is 300A~1500A.

[0119] Step S3, when the plasma furnace is heated to 1500℃-3000℃, the carbon source and hydrogen are introduced into the longitudinal hollow cavity of the anode 11 from bottom to top, and the volume fractions of the carbon source, hydrogen and inert gas are adjusted, wherein the volume fraction of the carbon source is 10%-50%; the volume fraction of hydrogen is 1%-60%, and the rest is inert gas, preferably, the gas volume ratio of the above-mentioned carbon source gas, hydrogen and inert gas is adjusted to 20%:40%:40%; wherein the carbon source gas is C1-C4 alkane, preferably methane, ethane, ethylene, acetylene, propylene and / or propane, and the inert gas is any one, two or three of nitrogen, argon and helium, preferably argon. Hydrogen can be introduced into the longitudinal hollow cavity of the anode from the bottom to the top together with the inert gas from the carrier gas inlet, or hydrogen can be introduced into the longitudinal hollow cavity of the anode from the bottom to the top together with the carbon source from the carbon source gas inlet, while the catalyst is injected into the longitudinal hollow cavity of the anode 11 from the bottom to the top in a spiral feeding manner by opening the catalyst spiral feeding bin 19, and the feeding rate of the catalyst is adjusted to 1 g / min-100 g / min. The carbon source gas and hydrogen react with the suspended catalyst in the non-transferred arc discharge ring cavity 112 formed between the anode and the cathode rod for 0.1 s-10 s to generate carbon nanotubes, preferably the residence time of the catalyst is 0.3 s-8 s, more preferably 0.6 s-6 s, and further preferably 1 s-4 s. Wherein, the radial spacing of the non-transferred arc discharge ring cavity 112 is 2.5 mm-20 mm, such as 3 mm, 5 mm, 15 mm, 18 mm, etc., preferably 8 mm-13 mm, such as 10 mm, 12 mm, etc.; the axial length of the non-transferred arc discharge ring cavity 112 is 200 mm-1000 mm, such as 300 mm, 400 mm, 800 mm, 900 mm, etc., preferably 500 mm-700 mm, preferably 500 mm-700 mm.

[0120] Step S4, the generated gaseous carbon nanotubes and tail gas are discharged from the material outlet 16 on one side of the top of the plasma furnace. The carbon nanotubes are collected by the collection device 3 after rapid cooling by the condenser 2, and the tail gas is discharged from the system after passing through the induced draft system 4, and then enters the recycling device or is discharged into the atmosphere after treatment. This method can realize the continuous preparation of carbon nanotubes.

[0121] Example 1

[0122] Step S1, first, the hollow cavity of the anode of the plasma furnace is evacuated to a vacuum state, such as 50 kPa, and then the iron powder catalyst is placed in the catalyst spiral feeding bin 19.

[0123] In step S2, argon gas with a starting flow rate of 60 slm is introduced into the hollow cavity of the anode 11 from bottom to top through the carrier gas inlet 17 and the inlet channel 131 to form an inert gas atmosphere; at the same time, the starting current is set to 80A, the power is turned on and the current is adjusted to successfully ignite the arc; then the inert gas flow rate is adjusted to 300 slm and the plasma current is adjusted to 1200A to heat the plasma furnace.

[0124] In step S3, when the plasma furnace is heated to approximately 1600°C, methane and hydrogen are introduced from bottom to top into the longitudinal hollow cavity of the anode 11, and the volume ratio of methane, hydrogen, and inert gas is adjusted to 20%:40%:40%. Hydrogen can be introduced from bottom to top into the longitudinal hollow cavity of the anode along with the inert gas through the carrier gas inlet, or hydrogen can be introduced from bottom to top into the longitudinal hollow cavity of the anode along with the carbon source gas through the carbon source inlet. At this time, the total gas flow rate of the carbon source gas, hydrogen, and inert gas is 400 slm. Simultaneously, the catalyst spiral feed chamber 19 is opened to inject the catalyst from top to bottom into the longitudinal hollow cavity of the anode 11 using a spiral feed method, and the catalyst feed rate is adjusted to 80 g / min. The carbon source gas and catalyst reside in the non-transfer arc discharge annular cavity 112 for 3 seconds, and the reaction continues for 6 hours.

[0125] In step S4, the generated carbon nanotubes and exhaust gas are both discharged from the carbon material outlet 16 on one side of the top of the non-transfer arc plasma furnace. The carbon nanotubes are rapidly cooled by the condenser 2 and then collected by the collection device 3, while the exhaust gas is discharged from the system via the induced draft system 4.

[0126] The prepared carbon nanotubes were analyzed by Raman Roman diffraction, such as... Figure 12 As shown, at 1000cm -1 ~3000cm -1 The presence of characteristic peaks of single-walled carbon nanotubes at the specified location, along with IG / ID=63, indicates that the single-walled carbon nanotubes prepared using the equipment and method provided in this invention have high crystallinity and good morphology.

[0127] Of course, the plasma furnace and preparation system provided by this invention can also be used to prepare other carbon nanotubes, such as graphene, by adjusting the corresponding reaction, which will not be elaborated here.

[0128] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A fluidized bed plasma furnace for continuous production of carbon nanotubes, characterized by, The fluidized bed plasma furnace comprises a fluidized bed plasma generator, which comprises: an anode with a longitudinal hollow cavity inside; an air inlet channel communicating with a lower port of the hollow cavity of the anode; a catalyst feeding port communicating with one side of an upper port of the hollow cavity of the anode, so that the hollow cavity of the anode forms a catalyst powder slow-settling zone.

2. The fluidized bed plasma furnace of claim 1, wherein, The fluidized bed plasma generator further comprises: a cathode assembly having a cathode rod arranged in the hollow cavity of the anode.

3. The fluidized bed plasma furnace according to claim 2, wherein the fluidized bed plasma furnace comprises a catalyst screw feeding bin arranged above the fluidized bed plasma generator, a bin bottom of the catalyst screw feeding bin communicating with the catalyst feeding port; preferably, the bin bottom of the catalyst screw feeding bin is provided with a screw rod type structure capable of screw feeding.

4. The fluidized bed plasma furnace of claim 1, wherein The fluidized bed plasma furnace further comprises: carrier gas inlets and carbon source inlets arranged at the bottom of the fluidized bed plasma furnace and communicating with the inlet of the air inlet channel; preferably, a gas distribution ring is further arranged in the air inlet channel, so that the working gas entering the carrier gas inlets and the carbon source gas entering the carbon source inlets are mixed uniformly by the gas distribution ring and then fed into the catalyst powder slow-settling zone; material outlets arranged at the top of the fluidized bed plasma furnace and communicating with the other side of the upper port of the hollow cavity of the anode.

5. The fluidized bed plasma furnace of claim 2, wherein The cathode assembly further comprises: a rotating driving mechanism directly or indirectly connected with the cathode rod to drive the cathode rod to rotate in the hollow cavity of the anode; a cathode water cooling jacket fixedly connected with the cathode rod at a lower end, and the rotating driving mechanism is drivingly connected with an upper section of the cathode water cooling jacket, preferably, the rotating driving mechanism and the upper section of the cathode water cooling jacket are drivingly connected by means of a gear assembly, more preferably, a driving gear disc is arranged on a shaft of the rotating driving mechanism, and a driven gear disc is arranged on the cathode water cooling jacket, and the driving gear disc and the driven gear disc are meshingly connected.

6. The fluidized bed plasma furnace of claim 5, wherein The cathode water cooling jacket comprises: a water cooling outer tube, a first end of the water cooling outer tube fixedly connected with one end of the cathode rod, and the driving mechanism drivingly connected with the water cooling outer tube by means of a gear assembly, so as to drive the cathode rod to rotate; a water cooling inner tube arranged in the water cooling outer tube, so that a cold water circulation passage is formed between an inner cavity of the water cooling inner tube and an inner cavity of the water cooling outer tube; a cathode mounting seat mounted on one end face of the plasma generator, and the cathode water cooling jacket arranged in the cathode mounting seat, so that the cathode rod is indirectly mounted on the cathode mounting seat.

7. The fluidized bed plasma furnace according to claim 6, wherein the first end of the water cooling outer tube is a closed end, and an outer side of the closed end of the water cooling outer tube is fixedly connected with one end of the cathode rod; the first end of the water cooling inner tube is an open end, and the open end of the water cooling inner tube is spaced apart from the closed end of the water cooling outer tube, so that a cold water circulation passage is formed between the inner cavity of the water cooling inner tube and the inner cavity of the water cooling outer tube. Preferably, the cathode water cooling jacket further comprises: a water inlet communicating with the inner cavity of the water cooling inner tube; preferably, the water cooling inner tube is provided with a water passing ring, one end of the water passing ring communicates with the water inlet, and the other end of the water passing ring communicates with the inner cavity of the water cooling inner tube, more preferably, the pipe wall of the water cooling inner tube is provided with a plurality of pipe holes, and the ring of the water passing ring is provided with a plurality of ring holes communicating with the corresponding pipe holes; a water outlet communicating with the inner cavity of the water cooling outer tube.

8. The fluidized bed plasma furnace of claim 6, wherein The cathode assembly further comprises a shaft end sealing member, a sealing cover is arranged at the second end of the cathode water cooling jacket, and the shaft end sealing member comprises: a hollow sealing seat arranged outside the second end of the cathode water cooling jacket; two first shaft sealing rings arranged in parallel and tightly arranged outside the second end of the water cooling outer tube and tightly arranged in the first end of the sealing seat; at least one second shaft sealing ring tightly arranged outside the second end of the water cooling inner tube and tightly arranged in the second end of the sealing seat; at least one third shaft sealing ring tightly arranged outside the second end of the water cooling inner tube and tightly arranged in the sealing seat; the second end of the water cooling inner tube is provided with a water passing ring communicating with the water inlet, and the water passing ring is arranged in the sealing seat and located between the second shaft sealing ring and the third shaft sealing ring.

9. The fluidized bed plasma furnace of claim 8, wherein The hollow interior of the sealing seat has a first step, a second step and a third step at the first end, and a fourth step at the second end; the end of the second end of the water cooling outer tube is inserted into the cavity formed by the first step of the first end of the sealing seat; the first shaft sealing ring is tightly arranged outside the second end of the water cooling outer tube, and tightly arranged on the second step of the first end of the sealing seat and the inner wall of the cavity formed by the second step; the shaft end sealing member further comprises a hollow first shaft sealing gland, the first shaft sealing gland is arranged outside the second end of the water cooling outer tube and arranged in the cavity formed by the third step of the first end of the sealing seat and tightly arranged on one side of the first shaft sealing ring; the second shaft sealing ring is tightly arranged outside the second end of the water cooling inner tube, and tightly arranged on the fourth step of the second end of the sealing seat and the inner wall of the cavity formed by the fourth step; the shaft end sealing member further comprises a second shaft sealing gland, the outer edge of the first side surface of the second shaft sealing gland is fixed, preferably by bolts, on the side surface of the second end of the sealing seat, and the first side surface of the second shaft sealing gland is tightly arranged on the second shaft sealing ring; Preferably, the rotary drive mechanism further comprises: a drive mounting seat fixedly arranged on one side of the sealing seat, and a drive motor mounted on the drive mounting seat; a bearing arranged in the cavity formed by the third step of the first end of the sealing seat, so that the drive motor of the drive mechanism drives the water cooling outer tube of the cathode water cooling jacket to rotate while the sealing seat and the water cooling inner tube of the cathode water cooling jacket do not rotate, preferably, the bearing is located on one side of the first shaft sealing gland.

10. The fluidized bed plasma furnace of claim 9, wherein the second shaft sealing gland is a hollow second shaft sealing gland arranged outside the second end of the water cooling inner tube; the shaft end sealing member further comprises: A hollow small shaft positioning cover is located on the second side of the second shaft seal cover and is fixed to the side of the second end of the sealing seat, preferably by bolts; A solid fixed small shaft is fixed in the small shaft positioning cover through a bolt and a gasket, and is fixed in the small shaft positioning cover through a compression ring gasket on the second end face of the small shaft positioning cover. The first end of the fixed small shaft is fixedly connected with the end face of the second end of the water-cooled inner tube through a reverse opening groove welding to fix the water-cooled inner tube.

11. A carbon nanotube production system, comprising: a carbon nanotube production chamber; a carbon nanotube production source; and a carbon nanotube production control system. Comprise: The fluidized bed plasma furnace of any one of claims 1-10; A condenser having a condenser inlet and a condenser outlet, the condenser inlet being in communication with the material outlet of the fluidized bed plasma furnace; A collection device for collecting the condensed product, having a collection inlet and a collection outlet, the collection inlet being in communication with the condenser outlet; An air induction system having an air inlet and an air outlet, the air inlet being in communication with the collection outlet.

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