Apparatus and method for preparing single-walled carbon nanotubes

Abstract

The application discloses a kind of single-walled carbon nanotube preparation device and method, belong to carbon nanotube technical field, wherein preparation device includes the heating bin for heating and gasification of solid catalyst, heating bin is fixed with gas inlet pipe and gas outlet pipe, gas inlet pipe is used to pass into carrier gas in heating bin, gas outlet pipe is used to deliver the mixed gas of gaseous catalyst and carrier gas to reactor, the top of heating bin is fixed with transfer bin, transfer bin is provided with feed inlet, discharge port and first air hole, transfer bin is also provided with sealing assembly for sealing feed inlet and discharge port, first air hole is connected with vacuum pump by pipeline;The preparation device provided in the embodiment of the application, by setting transfer bin, catalyst is added to transfer bin first, all air in transfer bin is extracted by vacuum pump, then solid catalyst is added to heating bin by opening discharge port, ensure continuous production, avoid the entry of external air during catalyst adding process.

Description

Technical Field

[0001] This invention relates to the field of carbon nanotube technology, and specifically discloses an apparatus and method for preparing single-walled carbon nanotubes. Background Technology

[0002] Carbon nanotubes, also known as buckytubes, are one-dimensional quantum materials with a special structure. They possess extremely high strength, excellent electrical and thermal conductivity, and good chemical stability, and are widely used in materials science and electronic technology. Carbon nanotubes include single-walled carbon nanotubes and multi-walled carbon nanotubes. Their preparation methods include arc discharge, laser evaporation, and chemical vapor deposition. Floating catalyst chemical vapor deposition (FCCVD) is a special chemical vapor deposition (CVD) process. The preparation process can be roughly divided into catalyst preparation, vapor deposition, carbon nanotube collection, and carbon nanotube purification. The catalyst needs to be introduced into the reaction chamber in a gaseous or vaporized form.

[0003] For example, patent CN218200074U, published on January 3, 2023, discloses a quantitative conveying device for carbon nanotube catalysts, including: a quantitative mechanism and a conveying mechanism. The quantitative mechanism includes a hopper, which has interconnected inner chambers. The bottom opening of the inner chambers is movably connected to a hopper door via an opening and closing component. Weighing components are symmetrically arranged on both sides of the outer wall of the hopper. The weighing components include a support rod with an open top groove. A pressure sensor is slidably connected in the groove. A connecting rod is detachably connected above the pressure sensor. The connecting rod is slidably connected in the groove, and the top of the connecting rod extends out of the groove and is fixedly connected to a support plate. The support plate is fixedly connected to the outer wall of the hopper. The conveying mechanism includes a conveying cylinder located below and connected to the hopper. The bottom end of the support rod is fixedly connected to the conveying cylinder. A push plate is slidably connected in the conveying cylinder. This device can improve the quantitative accuracy of the catalyst raw materials, reduce errors, reduce dust diffusion, and improve production efficiency.

[0004] In actual production, during the process of gasifying the catalyst, it is necessary to replenish the catalyst to the heating device periodically to ensure continuous production. However, since the heating device needs to be sealed, outside air can easily enter the heating device during the catalyst addition process, leading to an increase in by-products and a decrease in yield and quality. Summary of the Invention

[0005] The purpose of this invention is to provide an apparatus and method for preparing single-walled carbon nanotubes.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An apparatus for preparing single-walled carbon nanotubes includes a heating chamber for heating and gasifying a solid catalyst. An inlet pipe and an outlet pipe are fixedly connected to the heating chamber. The inlet pipe is used to introduce carrier gas into the heating chamber, and the outlet pipe is used to transport a mixture of gaseous catalyst and carrier gas to a reactor. A transfer chamber is fixedly connected to the top of the heating chamber. The transfer chamber is provided with an inlet, an outlet, and a first vent. The transfer chamber is also provided with a sealing assembly for sealing the inlet and outlet. The first vent is connected to a vacuum pump through a pipe.

[0008] The above-mentioned preparation apparatus includes a crucible and a heating component for heating the crucible in the heating chamber.

[0009] In the above-mentioned preparation device, the transfer chamber is vertically installed on the top of the heating chamber, and the lower end of the transfer chamber extends into the heating chamber. The sealing assembly includes an upper cover hinged to the feed inlet of the transfer chamber and a lower cover hinged to the discharge outlet. The upper cover is driven to rotate to cover the feed inlet, and the lower cover is driven to rotate to cover the discharge outlet.

[0010] In the above-mentioned preparation device, the transfer chamber is fixed to the edge of the upper surface of the heating chamber, and a receiving hopper is fixed to the heating chamber below the discharge port. A guide trough is inclinedly arranged below the receiving hopper, and the end of the guide trough away from the receiving hopper extends to one side above the crucible.

[0011] In the aforementioned preparation apparatus, a locking element is provided on the transfer chamber at the position corresponding to the lower cover. The locking element is used to lock the lower cover to maintain a seal against the discharge port.

[0012] The preparation device described above has a disc-shaped lower cover and a locking element including a stop block arranged radially along the lower cover. The stop block is driven to move radially along the lower cover and has an extended state that can prevent the lower cover from rotating.

[0013] The aforementioned preparation device, the locking component also includes an airbag fixed to the transfer chamber. The airbag expands or contracts along the moving direction of the stop block. The stop block is fixedly connected to one end of the airbag. A spring is installed inside the airbag. When the spring is in its natural state, the airbag is filled with gas and the pin is kept in the extended state. The airbag is connected to the internal space of the transfer chamber. The end of the stop block away from the airbag is wedge-shaped.

[0014] The aforementioned preparation apparatus also has a second air hole on the side wall of the transfer chamber. The second air hole is used to introduce carrier gas into the transfer chamber after the space inside the transfer chamber is evacuated in order to balance the gas pressure.

[0015] In the aforementioned preparation apparatus, both the first and second air holes are located on the upper part of the transfer chamber. A valve stem is rotatably mounted on the side wall of the transfer chamber. The valve stem has a first hole that can communicate with the first air hole and a second hole that can communicate with the second air hole. During the rotation stroke of the first valve stem, only one of the first and second air holes is always connected to the interior of the transfer chamber.

[0016] A method for preparing single-walled carbon nanotubes using the above-described preparation apparatus comprises the following steps:

[0017] S1: Place the solid catalyst into the heating chamber and heat it to vaporize;

[0018] S2: Carrier gas is introduced into the heating chamber through the air inlet pipe, so that the carrier gas is mixed with the gaseous catalyst produced by gasification;

[0019] S3: The mixture of carrier gas and gaseous catalyst is introduced into the reactor through the outlet pipe. At the same time, hydrocarbon gas is introduced into the reactor as a carbon source. The carbon source is deposited into single-walled carbon nanotubes under the action of the gaseous catalyst.

[0020] In the above technical solution, the preparation device provided in the embodiments of the present invention sets up a transfer chamber and sets up sealing components corresponding to the feed inlet and discharge outlet of the transfer chamber, and sets up a first air hole for vacuuming on the transfer chamber. After the catalyst is added to the transfer chamber, the air in the transfer chamber is first completely extracted by a vacuum pump, and then the discharge outlet is opened to add the solid catalyst to the heating chamber, which ensures continuous production while avoiding the entry of outside air during the catalyst addition process. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0022] Figure 1 This is a schematic diagram of the overall structure provided in an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the internal structure of the heating chamber provided in an embodiment of the present invention;

[0024] Figure 3 This is a top view showing the positional relationship between the crucible, receiving hopper, and guide trough provided in an embodiment of the present invention.

[0025] Figure 4 A cross-sectional view of a transit warehouse provided in an embodiment of the present invention;

[0026] Figure 5 Provided for embodiments of the present invention Figure 4 Enlarged view of point A in the middle;

[0027] Figure 6 This is a schematic diagram of the valve stem provided in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Heating chamber; 11. Air inlet pipe; 12. Air outlet pipe; 13. Crucible; 14. Receiving hopper; 15. Guide trough; 16. Induction coil; 2. Transfer chamber; 21. Feed inlet; 22. Discharge outlet; 23. First air hole; 24. Top cover; 25. Bottom cover; 26. Sealing ring; 27. Housing cavity; 28. Connecting hole; 29. ​​Second air hole; 3. Locking element; 31. Stop block; 32. Airbag; 33. Spring; 4. Valve stem; 41. First hole; 42. Second hole; 43. Third hole. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," and "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] like Figures 1 to 6 As shown in the figure, an apparatus for preparing single-walled carbon nanotubes provided in this embodiment of the invention includes a heating chamber 1 for heating and gasifying a solid catalyst. An inlet pipe 11 and an outlet pipe 12 are fixedly connected to the heating chamber 1. The inlet pipe 11 is used to introduce carrier gas into the heating chamber 1, and the outlet pipe 12 is used to transport the mixture of gaseous catalyst and carrier gas to a reactor. A transfer chamber 2 is fixedly connected to the top of the heating chamber 1. The transfer chamber 2 is provided with an inlet 21, an outlet 22 and a first vent 23. The transfer chamber 2 is also provided with a sealing assembly for sealing the inlet 21 and the outlet 22. The first vent 23 is connected to a vacuum pump through a pipe.

[0033] Specifically, this device is used for the preheating and gasification of solid catalysts during the preparation of carbon nanotubes, and for conveying the gasified catalysts to a reactor. Its main structure is a heating chamber 1, which is cylindrical with diameters at its upper and lower ends larger than its outer diameter in the middle. The inner cavity of the heating chamber 1 (hereinafter referred to as the main cavity) is cylindrical. The heating chamber 1 is equipped with an inlet pipe 11 and an outlet pipe 12. Figure 1 As shown, both the inlet pipe 11 and the outlet pipe 12 are fixed to the top of the heating chamber 1. Preferably, the inlet pipe 11 and the outlet pipe 12 are symmetrically arranged on the top of the heating chamber 1 to ensure that the carrier gas has sufficient time to mix with the gaseous catalyst in the heating chamber 1. The inlet pipe 11 is connected to a carrier gas tank containing inert gas, while the outlet pipe 12 is connected to the reactor. In addition, a transfer chamber 2 is also installed on the heating chamber 1. The transfer chamber 2 is fixed to the top of the heating chamber 1 and is provided with an inlet 21 and an outlet 22. The inlet 21 is connected to the external space to facilitate the addition of solid catalyst to the transfer chamber 2, while the outlet 22 is connected to the internal space of the heating chamber 1 to facilitate the removal of solid catalyst from the transfer chamber 2. The solid catalyst is added to the heating chamber 1 for vaporization. To prevent outside air from entering the heating chamber 1 when the solid catalyst is replenished, sealing components are installed at the inlet 21 and the outlet 22. The sealing components are used to close the inlet 21 or the outlet 22, or both at the same time. The sealing components can be existing electrically controlled gate valves (not shown in the figure). The transfer chamber 2 is also provided with a first air hole 23, which is connected to the vacuum pump. Electrically controlled valves (not shown in the figure) are installed at the inlet pipe 11, the outlet pipe 12 and the first air hole 23. Using electrically controlled gate valves to seal the inlet 21 or the outlet 22, and using electrically controlled valves to seal the inlet pipe 11, the outlet pipe 12 and the first air hole 23 are all existing technologies and can be directly applied without further explanation.

[0034] During production preparation, the inlet 21 of the transfer chamber 2 is first sealed with a sealing assembly, while the outlet 22 remains connected to the heating chamber 1. The first vent 23 and the electric control valve at the outlet pipe 12 are opened, while the electric control valve at the inlet pipe 11 is closed. The vacuum pump is then started to evacuate the space inside the heating chamber 1 and the reactor. Next, the electric control valve at the outlet pipe 12 is closed, and the outlet 22 is sealed with the sealing assembly. The inlet 21 is then opened to add solid catalyst to the transfer chamber 2. After the solid catalyst is added to the transfer chamber 2, the inlet 21 is sealed with the sealing assembly, the vacuum pump is started again to evacuate the space inside the transfer chamber 2, and finally the outlet 22 is opened to add the solid catalyst from the transfer chamber 2 to the heating chamber 1. Obviously, to facilitate precise temperature adjustment inside the heating chamber 1, an infrared temperature sensor (not shown in the figure) is also installed inside the heating chamber 1 to monitor the temperature inside the heating chamber 1.

[0035] During production, the heating chamber 1 is first heated. The heating method for the heating chamber 1 can be either existing resistance heating or electromagnetic induction heating. Then, the electrically controlled valves at the inlet pipe 11 and outlet pipe 12 are opened, allowing inert carrier gas to enter the heating chamber 1 through the inlet pipe 11. The carrier gas can be inert gases such as nitrogen or argon, with argon being the preferred option. After mixing with the gaseous catalyst, the carrier gas reaches the reactor through the outlet pipe 12. Obviously, to prevent the gaseous catalyst from condensing during its passage into the reactor, the connection between the outlet pipe 12 and the reactor needs to be insulated. Insulating the pipe to prevent the condensation of the gas passing through it is existing technology and can be directly applied without further explanation. To facilitate the control of the temperature of the heating chamber 1, the flow of the carrier gas, and the operation of the vacuum pump based on the infrared temperature sensor measurement results, the preparation device also includes a PLC controller. Using the controller to control the opening and closing of the resistance heater (or electromagnetic induction heater) and the vacuum pump is existing technology and can be directly applied without further explanation.

[0036] The preparation apparatus provided in this embodiment of the invention, by setting up a transfer chamber 2 and setting sealing components corresponding to the inlet 21 and outlet 22 of the transfer chamber 2, and setting a first air hole 23 for vacuuming on the transfer chamber 2, after the catalyst is added to the transfer chamber 2, firstly, the air in the transfer chamber 2 is completely removed by a vacuum pump, and then the outlet 22 is opened to add the solid catalyst to the heating chamber 1, ensuring continuous production while preventing the entry of outside air during the catalyst addition process.

[0037] Furthermore, the heating chamber 1 is provided with a crucible 13 and a heating assembly for heating the crucible 13.

[0038] Specifically, in the above embodiments, the solid catalyst inside the transfer chamber 2 is vaporized by heating the entire transfer chamber 2. However, due to the large space inside the transfer chamber 2, energy consumption is high, and centralized heating is not possible, resulting in low efficiency in the vaporization of the solid catalyst. In this embodiment, as... Figure 2 As shown, the heating chamber 1 is equipped with a crucible 13 and a heating assembly. The crucible 13 is made of graphite. The heating assembly includes an induction coil 16 fitted around the crucible 13, as well as a medium-frequency power supply and a water cooling system (not shown in the figure). This is existing technology and can be directly applied. In this embodiment, medium-frequency induction heating is used to heat the graphite crucible 13, which has the advantages of high heating efficiency, fast speed and high precision, and is beneficial for temperature control during solid catalyst gasification.

[0039] In another embodiment of the present invention, the transfer chamber 2 is vertically installed on the top of the heating chamber 1, and the lower end of the transfer chamber 2 extends into the heating chamber 1. The sealing assembly includes an upper cover 24 hinged to the feed inlet 21 of the transfer chamber 2 and a lower cover 25 hinged to the discharge outlet 22. The upper cover 24 is driven to rotate to cover the feed inlet 21, and the lower cover 25 is driven to rotate to cover the discharge outlet 22.

[0040] Specifically, in the above embodiment, an electrically controlled gate valve is used for sealing at the inlet 21 and outlet 22. During the opening and closing process, the sealing ring 26 of the electrically controlled gate valve is easily damaged due to friction with the solid catalyst. In this embodiment, the transfer chamber 2 is vertically installed on top of the heating chamber 1, such as... Figure 1 and Figure 2 As shown, a cylindrical cavity (hereinafter referred to as the transfer chamber) extends vertically through the transfer chamber 2. The inlet 21 is the upper opening of the transfer chamber, and the outlet 22 is the lower opening. The lower end of the transfer chamber 2 extends into the heating chamber 1, so that the lower opening can be located within the heating chamber 1. The sealing assembly includes an upper cover 24 and a lower cover 25 hinged to the transfer chamber 2. The upper cover 24 is positioned corresponding to the inlet 21 and can completely cover the inlet 21. The lower cover 25 is positioned corresponding to the outlet 22 and can completely cover the outlet 22. The sealing assembly also includes components connected to the upper cover 24 or the lower cover 25. The two sealing rings 26 that fit the cover 25 are preferably fixed to the upper and lower end faces of the transfer chamber 2, and the sealing rings 26 are coaxially arranged with the transfer cavity inside the transfer chamber 2. This arrangement ensures that the surface of the lower cover 25 is flat when it is opened, thereby preventing solid catalyst residue from remaining on the lower cover 25 and affecting the seal. Obviously, in order to ensure that the solid catalyst in the transfer chamber 2 can be smoothly put into the crucible 13, in this embodiment, the transfer chamber 2 is located directly above the crucible 13, and the lower end of the transfer chamber 2 needs to extend as far as possible to the crucible 13 to avoid spillage.

[0041] The transfer chamber 2 is also equipped with driving components corresponding to the upper cover 24 and the lower cover 25. These driving components are used to rotate the upper cover 24 or the lower cover 25, so that the upper cover 24 can block the feed inlet 21 and the lower cover 25 can block the discharge outlet 22. The driving components can use a motor and gears to drive the upper cover 24 or the lower cover 25. Using a motor to drive the upper cover 24 or the lower cover 25 is existing technology and can be directly applied without further explanation. Obviously, to ensure that the motor driving the lower cover 25 can be installed in the heating chamber 1... Externally, to prevent damage to the motor from high-temperature environments, a rotating shaft can be rotatably mounted on the transfer chamber 2. The shaft is vertically mounted, with its upper end extending through to the outside of the heating chamber 1 and connected to the motor drive. Its lower end is inside the heating chamber 1 and connected to the hinge shaft of the lower cover 25 via a gear set. This is existing technology and can be directly applied. The transmission relationship between the motor, gears, shaft, and the lower cover 25 is not shown in the diagram. It should be noted that the shaft and the heating chamber 1 need to be dynamically sealed to ensure a sealed environment inside the heating chamber 1.

[0042] In this embodiment, the upper cover 24 and the lower cover 25 are hinged to the transfer compartment 2, and driving components are provided for the upper cover 24 and the lower cover 25. During the opening or closing of the upper cover 24 and the lower cover 25, the sealing ring 26 will not be worn, thus extending the service life of the sealing ring 26.

[0043] Furthermore, the transfer chamber 2 is fixed to the edge of the upper surface of the heating chamber 1. A receiving hopper 14 is fixed inside the heating chamber 1 at a position below the discharge port 22. A guide trough 15 is inclinedly arranged below the receiving hopper 14. The end of the guide trough 15 away from the receiving hopper 14 extends to one side above the crucible 13.

[0044] Specifically, in the above embodiment, the transfer chamber 2 extends towards the crucible 13. On the one hand, this affects the rise of the gaseous particles after the solid catalyst is vaporized. On the other hand, the sealing ring 26 located on the lower end face of the transfer chamber 2 is close to the crucible 13, and the location of the crucible 13 is a high-temperature area in the heating chamber 1, making the sealing ring 26 prone to overheating and failure. In this embodiment, the transfer chamber 2 is fixed to the edge of the upper surface of the heating chamber 1, such as... Figure 2 and Figure 3 As shown, to ensure that the solid catalyst in the transfer chamber 2 can be smoothly added to the crucible 13, a receiving hopper 14 is fixedly connected to the heating chamber 1 below the discharge port 22. A guide trough 15 is inclinedly arranged below the receiving hopper 14. The guide trough 15 is fixedly connected to the inner wall of the heating chamber 1. The higher end of the guide trough 15 is below the receiving hopper 14, and the lower end of the guide trough 15 is on one side above the crucible 13. This minimizes the obstruction to the rising gaseous particles and keeps the sealing ring 26 at the lower end of the transfer chamber 2 away from the high-temperature area where the crucible 13 is located.

[0045] In another embodiment of the present invention, a locking member 3 is provided on the transfer chamber 2 at the position corresponding to the lower cover 25. The locking member 3 is used to lock the lower cover 25 so that it keeps the discharge port 22 sealed.

[0046] Furthermore, the lower cover 25 is disc-shaped, and the locking member 3 includes a stop 31 arranged radially along the lower cover 25. The stop 31 is driven to move radially along the lower cover 25, and the stop 31 has an extended state that can block the lower cover 25 from rotating.

[0047] Specifically, to prevent outside air from entering the heating chamber 1 and disrupting the protective atmosphere inside, the lower cover 25 must be opened only after vacuuming. However, in actual production, operators may mistakenly issue the instruction to open the lower cover 25 before vacuuming the transfer chamber 2. In this embodiment, a locking element 3 is provided on the transfer chamber 2 corresponding to the position of the lower cover 25. The lower cover 25 is disc-shaped, and the locking element 3 includes a stop 31 arranged radially along the lower cover 25, such as... Figure 4 and Figure 5 As shown, the lower part of the transfer chamber 2 protrudes downward along its own axis on the other side of the hinge position relative to the lower cover 25. A stop block 31 is slidably installed at this protruding position, and the stop block 31 slides radially along the transfer cavity within the transfer chamber 2. When the lower cover 25 maintains a sealed state over the discharge port, the stop block 31 is driven to extend downwards from the lower cover 25 and block the rotation of the lower cover 25 (this is the extended state of the stop block 31), thus maintaining the seal of the discharge port over the lower cover 25. In this embodiment, the drive of the stop block 31 can be achieved using an existing linear drive mechanism such as an electric push rod (not shown in the figure). Preferably, the electric push rod is horizontally fixed to the side wall of the heating chamber 1, and the stop block 31 is far from... One end of the block 31, located away from the central axis of the transfer chamber, passes through the side walls of the transfer chamber 2 and the heating chamber 1 in sequence, and is fixedly connected to the output end of the electric push rod. The block 31 is dynamically sealed to the heating chamber 1 to ensure a sealed environment inside the heating chamber 1. A pressure sensor (not shown in the figure) is also installed inside the transfer chamber 2. The pressure sensor monitors the pressure inside the transfer chamber 2 and feeds it back to the controller. The controller controls the electric push rod according to the feedback result of the pressure sensor, so that the electric push rod drives the block 31 to move to release the lock on the lower cover 25. With this configuration, the block 31 blocks the lower cover 25 to prevent the lower cover 25 from being opened by personnel due to accidental contact before the transfer chamber 2 is vacuumed.

[0048] Furthermore, the locking component 3 also includes an airbag 32 fixed to the transfer compartment 2. The airbag 32 expands or contracts along the moving direction of the stop block 31. The stop block 31 is fixedly connected to one end of the airbag 32. A spring 33 is provided inside the airbag 32. When the spring 33 is in its natural state, the airbag 32 is filled with gas and the pin is kept in the extended state. The airbag 32 communicates with the internal space of the transfer compartment 2. The end of the stop block 31 away from the airbag 32 is wedge-shaped.

[0049] Specifically, in the above embodiment, an electric push rod is used to drive the stop 31 to move radially along the transfer chamber to block the lower cover 25. Although this can prevent the operator from accidentally opening the lower cover 25 prematurely, the control of the electric push rod still relies on the cooperation of the controller and the air pressure sensor. When the controller malfunctions or the air pressure sensor fails, it may still cause the transfer chamber of the transfer compartment 2 to connect with the heating chamber 1 without being evacuated, resulting in a large amount of air in the transfer compartment 2 entering the heating chamber 1. In this embodiment, the locking member 3 also includes an airbag 32 disposed on the transfer compartment 2. The airbag 32 is made of a high-temperature resistant material such as flexible ceramic fiber and is coated with an airtight coating. A cylindrical placement cavity 27 is horizontally opened in the protruding position at the lower part of the transfer compartment 2. The airbag 32 is horizontally disposed in the placement cavity 27. The airbag 32 expands or contracts along the moving direction of the stop block 31 (i.e., the axial direction of the mounting cavity 27). The stop block 31 is fixedly connected to one end of the airbag 32 so that the stop block 31 can slide when the airbag 32 expands or contracts. The airbag 32 communicates with the internal space of the transfer chamber 2 through the connecting hole 28 opened on the side wall of the transfer chamber 2. In addition, a spring 33 is also provided inside the airbag 32. When the spring 33 is in its natural state, the airbag 32 is filled with gas, and the plug pin is in the above-mentioned extended state. In this state, if the lower cover 25 is closed at the discharge port 22, the lower cover 25 will be blocked by the plug pin and cannot be opened. Obviously, in specific implementation, a piston can also be installed in the mounting cavity 27 by dynamic sealing, and the piston can replace the airbag 32. The stop block 31 is fixedly connected to the piston, which can also achieve the effect of the airbag 32.

[0050] In this embodiment, by connecting the airbag 32 to the transfer chamber in the transfer compartment 2, the airbag 32 will remain in an inflated state when the transfer chamber in the transfer compartment 2 is not evacuated. At this time, the insertion pin remains in an extended state. When the lower cover 25 is driven to close to the discharge port 22, the edge of the lower cover 25, upon contacting the wedge-shaped portion on the stop block 31, can push the stop block 31 to move towards the side where the airbag 32 is located. The stop block 31 compresses the airbag 32 to contract while simultaneously compressing the spring 33 to deform and store force. When the lower cover 25 is completely closed, the stop block 31 is unobstructed, and the airbag 32 will expand again under the action of the spring 33, adjusting the stop block 31 to the aforementioned extended state to lock the lower cover 25. In the transfer chamber... During the vacuuming process, the air in the airbag 32 is also drawn out, forcibly causing the airbag 32 to contract. When the airbag 32 contracts, it drives the stop block 31 to move synchronously, causing the stop block 31 to contract into the interior of the protruding position at the bottom of the transfer chamber 2, no longer blocking the rotation of the lower cover 25. With this setting, while the vacuum pump is evacuating the transfer chamber in the transfer chamber 2, it can also drive the airbag 32 to contract, thereby passively driving the stop block 31 to move and release the obstruction of the lower cover 25. It can also ensure that the lower cover 25 will only be unlocked after the transfer chamber is evacuated. During this process, the gas in the airbag 32 is constantly replaced, and the heat at the airbag 32 is also constantly carried away with the gas replacement, thereby protecting the airbag 32.

[0051] In another embodiment of the present invention, the side wall of the transfer chamber 2 is also provided with a second air hole 29, which is used to introduce carrier gas into the transfer chamber 2 after the space inside the transfer chamber 2 is evacuated in order to balance the air pressure.

[0052] Specifically, since the lower cover 25 opens by rotation, and opening the lower cover 25 requires evacuation of the transfer chamber, the air pressure inside the heating chamber 1 is much higher than that inside the transfer chamber, resulting in significant resistance when opening the lower cover 25, which may even prevent the lower cover 25 from being driven open. In this embodiment, a second air hole 29 is provided on the side wall of the transfer chamber 2 to facilitate pipe connection, such as... Figure 1 and Figure 2 As shown, the positions of the first air hole 23 (second air hole 29) on the outer wall of the transfer chamber 2 are all protruding outward along the axial direction of the first air hole 23 (second air hole 29). The second air hole 29 is connected to the carrier gas tank storing inert gas through a pipe. A valve is installed on the pipe. When the transfer chamber is evacuated, the electric control valve at the first air hole 23 is closed, and the valve on the pipe connected to the second air hole 29 is opened. Inert gas is introduced into the transfer chamber through the pipe to balance the air pressure, thereby reducing the pressure difference between the transfer chamber and the main cavity of the heating chamber 1 (it can even make the air pressure of the transfer chamber and the main cavity equal). This reduces the resistance when the lower cover 25 is opened.

[0053] Furthermore, both the first air hole 23 and the second air hole 29 are located on the upper part of the transfer chamber 2. A valve stem 4 is rotatably installed on the side wall of the transfer chamber 2. The valve stem 4 has a first hole 41 that can communicate with the first air hole 23 and a second hole 42 that can communicate with the second air hole 29. During the rotation stroke of the first valve stem 4, only one of the first air hole 23 and the second air hole 29 is always connected to the interior of the transfer chamber 2.

[0054] Specifically, in actual operation, to avoid wasting inert gas, the first vent 23 and the second vent 29 cannot be simultaneously open (i.e., in communication with the transfer chamber). Using two sets of electrically controlled valves for separate control inevitably leads to accidental opening of both vents due to misoperation. In this embodiment, both the first vent 23 and the second vent 29 are located at the upper part of the transfer chamber 2, such as... Figure 1 , Figure 2 and Figure 4 As shown, a valve stem 4 is rotatably mounted on the side wall of the transfer chamber 2. The valve stem 4 is dynamically sealed to the side wall of the transfer chamber 2. The rotation of the valve stem 4 can be driven by a motor (not shown in the figure). Using a motor to drive the rotation of a cylinder is existing technology and can be directly applied, so it will not be elaborated further. The valve stem 4 has a first hole 41 and a second hole 42. Preferably, both the first hole 41 and the second hole 42 are radially arranged along the valve stem 4, and the first hole 41 and the second hole 42 are perpendicular to each other. During the rotation stroke of the valve stem 4, the valve stem 4 has a first angle and a second angle:

[0055] When at the first angle, such as Figure 1 As shown, the first air hole 23 is connected to the first hole 41. At this time, the first air hole 23 is connected to the transfer chamber 2 (transfer cavity) through the first hole 41, while the second air hole 29 is blocked by the valve stem 4, that is, the second air hole 29 is not connected to the transfer chamber 2 (transfer cavity).

[0056] When in the second angle, the first air hole 23 is blocked by the valve stem 4, that is, the first air hole 23 is not connected to the transfer chamber 2 (transfer cavity), while the second air hole 29 is connected to the second hole 42. At this time, the second air hole 29 is connected to the transfer chamber 2 (transfer cavity) through the second hole 42.

[0057] With this configuration, during the rotation stroke of the valve stem 4, only one of the first vent 23 and the second vent 29 can communicate with the transfer chamber, thereby avoiding the waste of inert gas caused by the first vent 23 and the second vent 29 being simultaneously connected to the transfer chamber.

[0058] Furthermore, the second air hole 29 is opened above the first air hole 23, and the valve stem 4 has a third hole 43 opened along its own axial direction. The end of the connecting hole 28 away from the air bag 32 is connected to the third hole 43, and the third hole 43 is connected to the first hole 41.

[0059] Specifically, in the above embodiment, the change in air pressure inside the airbag 32 during vacuuming causes the airbag 32 to contract, thereby causing the stop block 31 to contract into the side wall of the transfer chamber 2, so that it no longer obstructs the opening of the lower cover 25. However, during pressure balancing, when inert gas is introduced into the transfer chamber, since the airbag 32 remains in communication with the transfer chamber (so that the gas in the airbag 32 can be extracted together), the inert gas will also enter the airbag 32 through the connecting hole 28. As a result, the airbag 32 expands under the push of the spring 33, and drives the stop block 31 to move, so that the stop block 31 is adjusted to the extended state again. At this time, the lower cover 25 is still not opened. This will cause the lower cover 25 to be locked again by the stop block 31 after the transfer chamber is filled with inert gas and cannot be opened. In this embodiment, the second air hole 29 is opened above the first air hole 23, such as Figure 4 As shown, a third hole 43 is also provided on the valve stem 4 along its own axial direction. The end of the aforementioned connecting hole 28 away from the air bag 32 is connected to the third hole 43, and the end of the third hole 43 away from the connecting hole 28 is connected to the first air hole 23. With this configuration, before vacuuming, the valve stem 4 is adjusted to the aforementioned first angle. At this time, the air bag 32 is connected to the first air hole 23 through the connecting hole 28 and the third hole 43. During vacuuming, the gas in the transfer chamber and the air bag 32 will be extracted together. After vacuuming is completed, the valve stem 4 is driven to rotate to the second angle. At this time, the first air hole 23 is blocked by the valve stem 4, that is, the first hole 41 is offset from the first air hole 23. This causes the third hole 43 to no longer be connected to the first air hole 23, and the inert gas filled into the transfer chamber by the second air hole 29 cannot enter. In the airbag 32, the airbag 32 remains in a contracted state, causing the stop block 31 to retract into the side wall of the transfer chamber 2. At this time, the rotation of the lower cover 25 is not blocked by the stop block 31. After the solid catalyst is added, the lower cover 25 closes again. Since solid catalyst needs to be added to the transfer chamber 2 at this time, the upper cover 24 needs to be rotated to open the feed port 21 of the transfer chamber 2. However, before this, the valve stem 4 needs to be rotated to the first angle mentioned above. On the one hand, this avoids leakage of inert gas. On the other hand, it reconnects the airbag 32 with the first air hole 23, allowing outside air to enter the airbag 32. The airbag 32 will then expand under the action of the spring 33 and push the stop block 31 to move to adjust the stop block 31 to the extended state, and lock the lower cover 25 again.

[0060] The present invention also proposes a method for preparing single-walled carbon nanotubes using the above-mentioned preparation apparatus, the steps of which are as follows:

[0061] First, following the steps above, first evacuate the heating chamber 1, then fill the heating chamber 1 with carrier gas through the air inlet pipe 11, heat the crucible 13 through the heating component, then place the solid catalyst into the crucible 13 in the heating chamber 1. The solid catalyst is first added to the transfer chamber 2 according to the above operation, then the transfer chamber 2 is evacuated, then carrier gas is introduced into the transfer chamber to balance the gas pressure, and finally the solid catalyst is placed into the receiving hopper 14. The solid catalyst falls from the receiving hopper 14 into the guide trough 15 and is guided by the guide trough 15 into the crucible 13.

[0062] The second step is to continue to introduce carrier gas into the heating chamber 1 through the air inlet pipe 11, so that the carrier gas is mixed with the gaseous catalyst generated by gasification.

[0063] In the third step, the mixed gas of carrier gas and gaseous catalyst is introduced into the reactor through the gas outlet pipe 12. At the same time, hydrocarbon gas is introduced into the reactor as a carbon source. The carbon source is deposited into single-walled carbon nanotubes under the action of the gaseous catalyst.

[0064] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An apparatus for preparing single-walled carbon nanotubes, comprising a heating chamber for heating and vaporizing a solid catalyst, characterized in that, The heating bin is fixed with an air inlet pipe and an air outlet pipe. The air inlet pipe is used for introducing carrier gas into the heating bin. The air outlet pipe is used for conveying the mixed gas of gaseous catalyst and carrier gas to the reactor. The top of the heating bin is fixed with a transfer bin. The transfer bin is provided with a feeding port, a discharging port and a first air hole. The transfer bin is further provided with a sealing assembly for sealing the feeding port and the discharging port. The first air hole is connected with a vacuum pump through a pipeline. The transfer bin is vertically installed on the top of the heating bin and the lower end of the transfer bin penetrates into the heating bin. The sealing assembly comprises an upper cover hinged to the feeding port of the transfer bin and a lower cover hinged to the discharging port. The upper cover is driven to rotate to cover the feeding port. The lower cover is driven to rotate to cover the discharging port. The transfer bin is provided with a locking piece at a position corresponding to the lower cover. The locking piece is used for locking the lower cover to keep the sealing of the discharging port. The lower cover is disc-shaped. The locking piece comprises a stopper arranged in the radial direction of the lower cover. The stopper is driven to move in the radial direction of the lower cover. The stopper has an extended state capable of blocking the lower cover to prevent the rotation of the lower cover. The locking piece further comprises an air bag fixed to the transfer bin. The air bag is inflated or deflated along the moving direction of the stopper. The stopper is fixedly connected with one end of the air bag. The air bag is provided with a spring. When the spring is in a natural state, the air bag is filled with gas and the stopper is kept in the extended state. The air bag is in communication with the inner space of the transfer bin through a communication hole formed in the side wall of the transfer bin. The other end of the stopper is wedge-shaped. The side wall of the transfer bin is further provided with a second air hole. The second air hole is used for introducing carrier gas into the transfer bin to balance the air pressure after the inner space of the transfer bin is vacuumized. The first air hole and the second air hole are both formed in the upper part of the transfer bin. The side wall of the transfer bin is rotatably provided with a valve rod. The valve rod is provided with a first hole capable of being in communication with the first air hole. The valve rod is further provided with a second hole capable of being in communication with the second air hole. In the rotating stroke of the first valve rod, only one of the first air hole and the second air hole is in communication with the inner space of the transfer bin at all times. The second air hole is formed above the first air hole. The valve rod is further provided with a third hole in the axial direction of the valve rod. The other end of the communication hole is connected with the third hole. The other end of the third hole is in communication with the first air hole.

2. The apparatus according to claim 1, wherein The heating bin is provided with a crucible and a heating assembly for heating the crucible.

3. The apparatus according to claim 2, wherein The transfer bin is fixed to the edge position of the upper surface of the heating bin. A receiving hopper is fixed to the position below the discharging port in the heating bin. A guide chute is obliquely arranged below the receiving hopper. The other end of the guide chute extends to a position above the crucible.

4. A method for preparing single-walled carbon nanotubes by using the device for preparing single-walled carbon nanotubes according to any one of claims 1-3. S1: solid catalyst is put into the heating bin to be heated and gasified; S2: carrier gas is introduced into the heating bin through the air inlet pipe to mix with the gasified gaseous catalyst; S3: the mixed gas of carrier gas and gaseous catalyst is introduced into the reactor through the air outlet pipe. Hydrocarbon gas is introduced into the reactor as carbon source. The carbon source is deposited into single-walled carbon nanotubes under the action of gaseous catalyst.

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