Carbon nanotube generation apparatus

Abstract

A carbon nanotube production apparatus includes a first reaction tube to which a raw material gas for carbon nanotubes is supplied, a second reaction tube through which the raw material gas passes, and a heating chamber that heats the first reaction tube and the second reaction tube, the first reaction tube and the second reaction tube being arranged in a straight line, and an end portion of the first reaction tube and an end portion of the second reaction tube being connected.

Description

Technical Field

[0001] This invention relates to a carbon nanotube generating apparatus. Background Technology

[0002] Carbon nanotubes (hereinafter sometimes referred to as "CNTs") possess excellent properties such as electrical conductivity, thermal conductivity, and mechanical strength, making them a promising new material attracting attention in many fields. As for CNT manufacturing apparatus, Patent Document 1 discloses a chemical vapor deposition (CVD) method that uses the thermal decomposition of carbon-containing raw materials (carbon source) to generate CNTs.

[0003] In a CNT manufacturing method using chemical vapor deposition, for example, CNT feedstock and carrier gas are supplied to the interior of a reaction tube heated to a high temperature, and the feedstock passes through the interior of the reaction tube for a certain period of time, thereby generating CNTs. The generated CNTs are discharged from the end of the reaction tube opposite to the feedstock supply side.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 2019-064918 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] To reduce the cost of manufacturing CNTs, it is necessary to increase the amount of CNTs produced per unit time to improve manufacturing efficiency. One method to increase the amount of CNTs produced per unit time is, for example, to increase the feedstock supply to the reaction tube.

[0009] However, if the amount of CNTs generated increases with the increase of the feedstock supply, CNT blockage is likely to occur in the reaction tube. Therefore, in order to suppress CNT blockage, it is necessary to increase the flow rate of the carrier gas while increasing the feedstock supply.

[0010] On the other hand, in order to control the quality of CNTs within the target range, it is necessary to perform CNT generation processing for an appropriate time within an atmosphere set to suitable conditions. However, if the carrier gas flow rate is increased within the existing reaction tube length, it is difficult to achieve suitable processing conditions within the reaction tube. In other words, if the carrier gas flow rate is increased in the conventional device configuration, CNTs of the target quality cannot be obtained. Therefore, in order to obtain CNTs of the target quality even with an increased carrier gas flow rate, it is necessary to extend the reaction tube length according to the carrier gas flow rate.

[0011] However, reaction tube manufacturers produce several common sizes of reaction tubes, and manufacturing reaction tubes that deviate from these specifications incurs significant costs. Specifically, using reaction tubes that are longer than the standard specifications leads to a substantial increase in the cost of the CNT generation apparatus. Therefore, there is room for improvement in conventional CNT generation apparatuses from the perspective of increasing the CNT production rate per unit time while ensuring CNT quality.

[0012] The present invention was made in view of the above circumstances, and its object is to provide a carbon nanotube generating apparatus that increases the amount of carbon nanotubes generated per unit time while ensuring the quality of carbon nanotubes.

[0013] Solution for solving the problem

[0014] The following describes the technical solution of the present invention for solving the above problems.

[0015] (1) A carbon nanotube generating device, wherein,

[0016] This carbon nanotube generation device has the following features:

[0017] The first reaction tube is supplied with the raw material gas for the carbon nanotubes;

[0018] The second reaction tube through which the raw material gas passes; and

[0019] A heating chamber that heats the first reaction tube and the second reaction tube.

[0020] The first reaction tube and the second reaction tube are arranged in a straight line.

[0021] The end of the first reaction tube is connected to the end of the second reaction tube.

[0022] (2) The carbon nanotube generating apparatus according to (1), wherein,

[0023] The carbon nanotube generating apparatus includes a connecting member that connects the end of the first reaction tube and the end of the second reaction tube.

[0024] The connecting member has a first insertion port for inserting the end of the first reaction tube, a second insertion port for inserting the end of the second reaction tube, and an intermediate wall portion disposed between the first insertion port and the second insertion port.

[0025] The intermediate wall portion has a first surface facing and parallel to the end face of the first reaction tube, a second surface facing and parallel to the end face of the second reaction tube, and a through hole extending along the tube axis of the first reaction tube.

[0026] (3) The carbon nanotube generating apparatus according to (2), wherein,

[0027] A sealing element is provided between one or both of the end face of the first reaction tube and the intermediate wall portion and between the end face of the second reaction tube and the intermediate wall portion.

[0028] (4) The carbon nanotube generating apparatus according to (1), wherein,

[0029] The end of the first reaction tube on the second reaction tube side has a first outer diameter portion and a cylindrical second outer diameter portion with an outer diameter smaller than the first outer diameter portion.

[0030] The end of the second reaction tube on the first reaction tube side has a first inner diameter portion and a cylindrical second inner diameter portion with an inner diameter larger than the first inner diameter portion.

[0031] The second outer diameter portion is inserted into the inside of the second inner diameter portion.

[0032] (5) The carbon nanotube generating apparatus according to (4), wherein,

[0033] A sealing element is provided between the end face of the first outer diameter portion and the end face of the second inner diameter portion.

[0034] (6) The carbon nanotube generating apparatus according to (3) or (5), wherein,

[0035] The seal is made of graphite.

[0036] (7) The carbon nanotube generating apparatus according to any one of (3), (5), and (6), wherein,

[0037] The carbon nanotube generating device has a pressing mechanism that brings the first reaction tube and the second reaction tube relatively close together and seals them together through the sealing element.

[0038] (8) The carbon nanotube generating apparatus according to (7), wherein,

[0039] The end of the first reaction tube opposite to the side of the second reaction tube is located outside the heating chamber.

[0040] The pressing mechanism has:

[0041] A spring that extends and retracts in a direction parallel to the axis of the first reaction tube;

[0042] The first component, which has one end of the spring fixed thereon; and

[0043] The second component has the other end of the spring fixed to it.

[0044] The first component is fixed relative to the first reaction tube.

[0045] The second component is fixed relative to the heating chamber.

[0046] The spring is fixed to the second member in a state of contraction compared to its natural length in a region opposite to the region on the side of the second reaction tube, relative to the first member.

[0047] (9) The carbon nanotube generating apparatus according to (8), wherein,

[0048] The second component is a rod that passes through the inside of the spring.

[0049] (10) The carbon nanotube generating apparatus according to (8) or (9), wherein,

[0050] The carbon nanotube generating device has an adjustment mechanism for adjusting the amount of contraction of the spring.

[0051] (11) The carbon nanotube generating apparatus according to (9), wherein,

[0052] The bar has an external threaded portion.

[0053] A nut is installed on the external threaded portion.

[0054] The spring is disposed between the nut and the first member.

[0055] The carbon nanotube generating device has a structure that allows the amount of spring contraction to be adjusted by rotating the nut.

[0056] (12) The carbon nanotube generating apparatus according to any one of (1) to (11), wherein,

[0057] The arithmetic mean roughness Ra of the end face of the first reaction tube and the end face of the second reaction tube at the connection between the first reaction tube and the second reaction tube is 0.2 μm to 6.3 μm.

[0058] Invention Effects

[0059] According to the present invention, a carbon nanotube generating apparatus is provided that increases the amount of carbon nanotubes generated per unit time while ensuring the quality of carbon nanotubes. Attached Figure Description

[0060] Figure 1 This is an explanatory diagram showing the schematic structure of a carbon nanotube manufacturing apparatus according to an embodiment.

[0061] Figure 2This is an explanatory diagram showing the schematic structure of the carbon nanotube generation apparatus according to the embodiment.

[0062] Figure 3 This is a perspective view showing the connection between the first reaction tube and the second reaction tube.

[0063] Figure 4 This is a diagram used to illustrate the connection structure between the first reaction tube and the second reaction tube.

[0064] Figure 5 This is an explanatory diagram showing the schematic structure of the pressing mechanism that presses the first reaction tube downwards.

[0065] Figure 6 This is an explanatory diagram showing another example of the connection structure between the first reaction tube and the second reaction tube.

[0066] Figure 7 This is an explanatory diagram showing another example of the connection structure between the first reaction tube and the second reaction tube.

[0067] Figure 8 This is an explanatory diagram showing another example of the connection structure between the first reaction tube and the second reaction tube. Detailed Implementation

[0068] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in this specification and the accompanying drawings, elements having substantially the same functional structure are omitted from repeated description by using the same reference numerals.

[0069] Figure 1 This is an explanatory diagram showing the schematic structure of the CNT manufacturing apparatus 1 for manufacturing carbon nanotubes (hereinafter, sometimes referred to as "CNTs") according to this embodiment. In this specification, CNT refers to a tubular carbon allotrope (represented by a cylindrical structure with a graphite structure), including so-called single-walled CNTs, multi-walled CNTs, or carbon nanotubes with angular tips. The CNT manufacturing apparatus 1 is particularly suitable for manufacturing single-walled CNTs.

[0070] CNT manufacturing apparatus 1 includes a CNT generation apparatus 10 for generating CNTs and a recycling apparatus 60 for recycling CNTs.

[0071] The recycling device 60 is connected to the lower end of the CNT generating device 10. The recycling device 60 includes a recycling chamber 61, a roller 62 disposed within the recycling chamber 61, and a motor 63 that rotates the roller 62. The CNTs generated by the CNT generating device 10 are wound into a block-shaped coil by the rotating roller 62. The coil, now of a predetermined size, falls from the roller 62 into the recycling chamber 61 via a separation mechanism (not shown) and is then recycled.

[0072] <Carbon Nanotube Generation Device>

[0073] Figure 2 This is an explanatory diagram showing the schematic structure of the CNT generation apparatus 10 according to this embodiment. The CNT generation apparatus 10 is an apparatus for generating CNTs using a chemical vapor deposition (CVD) method, which generates CNTs by thermally decomposing a raw material such as a catalyst metal or a catalyst metal compound. Furthermore, when supplying the raw material for CNTs to the CNT generation apparatus 10, a carrier gas (e.g., hydrogen) is also supplied along with the raw material. In this specification, the raw material supplied along with the carrier gas is referred to as the raw material gas.

[0074] The CNT generating apparatus 10 includes a first reaction tube 11 to which the raw material gas for CNTs is supplied, a second reaction tube 12 connected to the lower end of the first reaction tube 11, and a heating chamber 13 for heating the first reaction tube 11 and the second reaction tube 12.

[0075] The tube axes of the first reaction tube 11 and the second reaction tube 12 are along the vertical direction, and these first reaction tubes 11 and second reaction tubes 12 are arranged in a straight line. In this embodiment, each reaction tube 11 and 12 is arranged such that the tube axis direction of the first reaction tube 11 is consistent with the tube axis direction of the second reaction tube 12.

[0076] The upper end of the first reaction tube 11 is located outside the heating chamber 13, and a raw material supply port (not shown) for supplying raw material gas for CNTs is formed at the upper end of the first reaction tube 11. The lower end of the first reaction tube 11 is connected to the upper end of the second reaction tube 12, and the raw material gas for CNTs supplied to the first reaction tube 11 flows into the second reaction tube 12 through the first reaction tube 11.

[0077] The connection structure between the first reaction tube 11 and the second reaction tube 12 will be described in detail later. However, the arithmetic mean roughness Ra of the lower end face of the first reaction tube 11 and the upper end face of the second reaction tube 12, as specified in JIS B 0601:2001, is preferably 0.2 μm to 6.3 μm. This improves the sealing performance at the connection between the first reaction tube 11 and the second reaction tube 12.

[0078] Each reaction tube 11 and 12 is a straight tubular body, but the shape of each reaction tube 11 and 12 is not particularly limited. Furthermore, the shape of the cross-section of each reaction tube 11 and 12 perpendicular to the tube axis can be circular, elliptical, oval, or other shapes with arcs, or polygonal. The material of each reaction tube 11 and 12 is selected with appropriate consideration of heat resistance, thermal shock resistance, weather resistance, and corrosion resistance relative to the heating temperature during CNT formation, as well as the atmospheric gas at that temperature. Materials such as alumina (Al2O3), mullite, silicon carbide (SiC), quartz glass, cantal (iron-chromium-aluminum alloy), chromium-nickel-iron alloy, and carbon are used.

[0079] The length of each reaction tube 11 and 12 is, for example, 0.5 to 4.0 m, preferably 1.0 to 3.0 m, and more preferably 2.0 to 2.5 m. Furthermore, the inner diameter of each reaction tube 11 and 12 is, for example, 10 to 300 mm, preferably 50 to 200 mm, and more preferably 80 to 120 mm. Moreover, the number of reaction tubes is not limited to two, and can be three or more. When there are three or more reaction tubes, they are arranged in a straight line.

[0080] The heating chamber 13 is, for example, a cylindrical shell, and an insulating material 14 is provided on the inner side of the wall of the heating chamber 13. A space 15 is formed inside the insulating material 14 and around each reaction tube 11, 12. A heater 16 for heating each reaction tube 11, 12 is provided in this space 15.

[0081] The shape and heating method of heater 16 are not particularly limited as long as they can heat each reaction tube 11 and 12 to a temperature suitable for CNT generation. For example, a tungsten heater capable of heating each reaction tube 11 and 12 to 500°C to 2000°C, or a carbon heater or silicon carbide heater (SiC heater) capable of heating to 600°C to 1600°C can be used as heater 16.

[0082] A thermocouple 17 for measuring the temperature within the space 15 is provided on the side wall of the heating chamber 13. Multiple thermocouples 17 are spaced apart along the height of the heating chamber 13, thereby enabling the measurement of the temperature distribution along the tube axis of each reaction tube 11, 12.

[0083] A protective gas supply pipe 18, communicating with the aforementioned space 15, is provided on the bottom wall of the heating chamber 13. An inert gas, for example, is supplied to the protective gas supply pipe 18 as a protective gas, creating an inert gas atmosphere within space 15 during CNT generation. An exhaust pipe 19, communicating with space 15, is provided on the top wall of the heating chamber 13, and is connected, for example, to the factory's exhaust system. The supply and discharge of the inert gas occur during CNT generation, and if the raw material gas leaks from the gap between the first reaction tube 11 and the second reaction tube 12, the raw material gas is discharged through the exhaust pipe 19.

[0084] (Connection structure of the reaction tube)

[0085] Figure 3 This is a perspective view showing the connection between the first reaction tube 11 and the second reaction tube 12. Figure 4 This is a diagram used to illustrate the connection structure between the first reaction tube 11 and the second reaction tube 12. Figure 4 (a) is an exploded view of the connection structure, showing the cross section when the connection of reaction tubes 11 and 12 is cut along the vertical direction. Figure 4(b) is a diagram showing the connection state of the first reaction tube 11 and the second reaction tube 12, showing the end face when the connection part of the reaction tubes 11 and 12 is cut along the vertical direction.

[0086] A connecting retainer 20 is provided between the lower end of the first reaction tube 11 and the upper end of the second reaction tube 12 as a connecting member to connect the first reaction tube 11 and the second reaction tube 12.

[0087] The connecting retainer 20 has a cylindrical sidewall portion 21, a first insertion port 22 for inserting the end of the first reaction tube 11, and a second insertion port 23 for inserting the second reaction tube 12.

[0088] The inner diameter of the side wall portion 21 is slightly larger than the outer diameter of each reaction tube 11, 12, and the outer peripheral surface of the end of each reaction tube 11, 12 inserted into the connecting retainer 20 is supported by the inner peripheral surface of the side wall portion 21.

[0089] Between the first insertion port 22 and the second insertion port 23, there is a middle wall portion 24 protruding inward from the inner circumferential surface of the side wall portion 21. The middle wall portion 24 has an upper surface (first surface) facing and parallel to the lower end face of the first reaction tube 11 and a lower surface (second surface) facing and parallel to the upper end face of the second reaction tube 12. The middle wall portion 24 is located at the center of the side wall portion 21 in the vertical direction, but its position in the vertical direction is not particularly limited as long as it can support each reaction tube 11, 12.

[0090] A through hole 25 is formed at the center of the intermediate wall portion 24 in the radial direction, extending along the tube axis of the first reaction tube 11. The diameter of the through hole 25 is smaller than the inner diameter of each reaction tube 11, 12, so that the lower end face of the first reaction tube 11 is supported by the upper surface of the intermediate wall portion 24, and the lower surface of the intermediate wall portion 24 is supported by the upper end face of the second reaction tube 12.

[0091] Furthermore, if the size of the through hole 25 is too small, the flow of the raw material gas will be obstructed by the intermediate wall portion 24, which may lead to the accumulation of CNTs on the upper surface of the intermediate wall portion 24 and blockage of the through hole 25 caused by CNTs. Therefore, the size of the through hole 25 is preferably as large as possible within a range that can maintain the stable posture of each reaction tube 11, 12 inserted into the connecting retainer 20. Specifically, the diameter A of the through hole 25, the inner diameter B of the first reaction tube 11, and the inner diameter C of the second reaction tube 12 are preferably in the relationship that A≥B=C.

[0092] The material of the connecting retainer 20 described above can be any material with heat resistance relative to the heating temperature during CNT formation; there are no particular limitations. For example, carbon or silicon carbide (SiC) can be used. Furthermore, since external gas can flow into the protective gas supplied... Figure 2 As shown in space 15, the atmosphere within space 15 contains oxygen due to the low purity of the protective gas. Therefore, for example, if the connection retainer 20 is made of carbon, it is easily oxidized by contact with oxygen that may be present in space 15 at high temperatures. On the other hand, if the connection retainer 20 is made of silicon carbide, such oxidation can be suppressed, enabling a longer lifespan for the connection retainer 20.

[0093] Furthermore, for example, if the thermal expansion rate of the connecting retainer 20 is too small relative to the thermal expansion rates of the reaction tubes 11 and 12, the expansion rate of the reaction tubes 11 and 12 during heating in the heating chamber is faster than that of the connecting retainer 20. Therefore, the reaction tubes 11 and 12 may expand further while their outer peripheral surfaces are in contact with the inner peripheral surfaces of the sidewall portion 21 of the connecting retainer 20. Conversely, for example, if the thermal expansion rate of the connecting retainer 20 is too large relative to the thermal expansion rates of the reaction tubes 11 and 12, the contraction rate of the connecting retainer 20 during cooling in the heating chamber is faster than that of the reaction tubes 11 and 12. Therefore, the connecting retainer 20 may contract further while its outer peripheral surfaces are in contact with the inner peripheral surfaces of the sidewall portion 21 of the connecting retainer 20.

[0094] In any of the above situations, damage to the reaction tubes 11, 12 or the connecting retainer 20 may occur. Therefore, the material of the connecting retainer 20 is preferably a material having a thermal expansion coefficient that is approximately the same as that of the materials of the reaction tubes 11, 12, and more preferably the material of the connecting retainer 20 is the same as that of the materials of the reaction tubes 11, 12.

[0095] Annular sealing gaskets 30 are provided as sealing elements between the lower end face of the first reaction tube 11 and the upper surface of the intermediate wall portion 24, and between the upper end face of the second reaction tube 12 and the lower surface of the intermediate wall portion 24. By providing these sealing gaskets 30, leakage of raw material gas from the gap between the first reaction tube 11 and the connecting retainer 20, or from the gap between the second reaction tube 12 and the connecting retainer 20, can be suppressed.

[0096] The material of the sealing gasket 30 is not particularly limited as long as it ensures the desired sealing performance. For example, metal oxides and carbon-based materials can be used, specifically alumina and graphite. While carbon-containing components may deteriorate upon contact with the CNT feed gas at high temperatures, the sealing gasket 30 is kept in a state where it is not easily exposed to the feed gas atmosphere because the intermediate wall 24 of each reaction tube 11, 12 and the connecting retainer 20 are tightly sealed. Therefore, even when the sealing gasket 30 is made of graphite, long-term stable sealing performance can be ensured.

[0097] The sealing gasket 30 is formed of a material that deforms under load, thereby expecting to achieve high sealing performance. Furthermore, when the sealing gasket 30 is a laminated structure formed by overlapping multiple such materials, the sealing performance is further improved. As a laminated structure, a laminated structure of sheet-like graphite films is preferred, for example.

[0098] In addition, Figure 4 In the example shown, gaskets 30 are provided between the first reaction tube 11 and the intermediate wall portion 24, and between the second reaction tube 12 and the intermediate wall portion 24. However, as long as the required sealing performance can be ensured, gaskets 30 may be provided only in either one. Alternatively, gaskets 30 may not be provided as long as the required sealing performance can be ensured.

[0099] The above describes the connection structure between the first reaction tube 11 and the second reaction tube 12. Furthermore, the shape of the connecting retainer 20 and the sealing gasket 30 are appropriately modified according to the horizontal cross-sectional shape of the reaction tubes 11 and 12.

[0100] (Pressing mechanism)

[0101] Next, the pressing mechanism 40, which is preferably provided to improve the sealing of the connection between the first reaction tube 11 and the second reaction tube 12, will be described. Figure 5 This is an explanatory diagram showing the schematic structure of the pressing mechanism 40 that presses the first reaction tube 11 downwards.

[0102] The pressing mechanism 40 has: an annular plate 41 fixed to the upper end of the first reaction tube 11 located outside the heating chamber 13; an annular plate 42 fixed to the lower surface of the plate 41; and an annular plate 43 fixed to the lower surface of the plate 42.

[0103] In addition, the pressing mechanism 40 has: an annular plate 44, which is fixed to the top wall 13a of the heating chamber 13; a cylindrical wall 45, which is fixed to the inner circumferential end of the plate 44; and an annular plate 46, which is fixed to the upper end of the cylindrical wall 45.

[0104] A corrugated pipe 47 is provided between plate 43 and plate 46 as a flexible member. The corrugated pipe 47 is configured with its extension and contraction direction parallel to the tube axis of the first reaction tube 11. The upper end of the corrugated pipe 47 is fixed to plate 43, and the lower end of the corrugated pipe 47 is fixed to plate 46.

[0105] The upper end of the first reaction tube 11 is surrounded by plates 41-43, a cylindrical wall portion 45, a plate 46, and a bellows 47 to form a space 48. A protective gas supply pipe (not shown) supplies a non-reactive gas to the space 48, creating a non-reactive gas atmosphere within the space 48 during CNT generation. Additionally, the non-reactive gas filling the space 48 flows into the heating chamber 13 through a through-hole 13b formed in the top wall portion 13a of the heating chamber 13, and exits through an exhaust pipe (e.g., not shown) Figure 2 Exhaust is discharged through the exhaust pipe 19 shown. In addition, seals are appropriately provided on the contact surfaces of the plates to prevent the protective gas from leaking from space 48 to the outside.

[0106] When the heating chamber 13 heats up, the first reaction tube 11 and the second reaction tube 12 elongate along the tube axis due to thermal expansion, but in this case, the bellows 47 also elongates. On the other hand, when the heating chamber 13 cools down, the expanded first reaction tube 11 contracts, so the first reaction tube 11 contracts along the tube axis, but in this case, the bellows 47 also contracts.

[0107] That is, the corrugated pipe 47 extends or contracts according to the elongation or contraction of the first reaction pipe 11. Therefore, when the first reaction pipe 11 expands or contracts, it can prevent the components such as plates 41 to 43, which are directly or indirectly fixed to the upper end of the first reaction pipe 11, as well as the reaction pipes 11 and 12 themselves, from breaking.

[0108] Furthermore, the pressing mechanism 40 preferably has a structure in which the bellows 47 extends or contracts according to the length change of the first reaction tube 11 in the tube axis direction as described above, but this structure may also be set as a mechanism independent of the pressing mechanism 40.

[0109] A spring 49 is provided above the plate 43 on the side of the bellows 47. The spring 49 is arranged so that its extension direction is parallel to the tube axis of the first reaction tube 11, and the lower end 49a of the spring 49 is fixed to the upper surface of the plate 43.

[0110] A rod 50 is inserted through the inner side of the spring 49, passing through the plate 43, and its lower end is fixed to the upper surface of the plate 46. The rod 50 can be a hollow or solid part, such as a tube. The upper end of the rod 50 is externally threaded, and a nut 51 is installed on the externally threaded part.

[0111] The lower surface of the nut 51 contacts the upper end 49b of the spring 49. By tightening the nut 51, the upper end 49b of the spring 49 moves downward, and the spring 49 contracts. That is, the upper end 49b of the spring 49 is fixed relative to the rod 50 by the nut 51. In other words, the spring 49 is located between the nut 51 and the plate 43, and the upper end 49b of the spring 49 is fixed relative to the rod 50 in the region of the plate 43 opposite to the side of the second reaction tube 12.

[0112] Multiple structures are provided, consisting of the aforementioned spring 49, rod 50, and nut 51. Here, if the component that fixes one end of the spring 49, i.e. the lower end 49a, is called the first component, and the component that fixes the other end of the spring 49, i.e. the upper end 49b, is called the second component, then the first component is equivalent to the plate 43, and the second component is equivalent to the rod 50.

[0113] As described above, plate 43 is fixed to plate 42, which is fixed to plate 41, which is fixed to the upper end of the first reaction tube 11. That is, plate 43, as the first component, is in a state where it is indirectly fixed to the upper end of the first reaction tube 11 by means of other components.

[0114] On the other hand, the rod 50, which is the second component, is fixed to the plate 46. The plate 46 is fixed to the cylindrical wall portion 45, which is fixed to the plate 44, which is fixed to the top wall portion 13a of the heating chamber 13. That is, the rod 50, which is the second component, is indirectly fixed to the heating chamber 13 via other components.

[0115] The spring 49, which is fixed to the plate 43 and the rod 50, is fixed to the plate 43 and the rod 50 in a state of contraction compared to its natural length by means of a fastening nut 51. Therefore, the spring 49 generates a restoring force in the contracted state, but the rod 50, which is fitted with the nut 51, is fixed relative to the heating chamber 13 by means of the plate 46, the cylindrical wall portion 45, and the plate 44, so the rod 50 is in a constrained state.

[0116] Therefore, the restoring force of the spring 49 acts in the direction toward the lower end 49a of the spring 49, applying a downward load to the upper surface of the plate 43. The plate 43 is fixed relative to the upper end of the first reaction tube 11 via the plates 42 and 41, so by inputting a downward load to the plate 43, the first reaction tube 11 is pressed downward.

[0117] Along with this, Figure 4The lower end face of the first reaction tube 11 is pressed against the upper surface of the intermediate wall portion 24 of the connecting retainer 20, and the lower surface of the intermediate wall portion 24 is pressed against the upper end face of the second reaction tube 12. This improves the sealing performance of the gasket 30 by enhancing the tightness between the lower end face of the first reaction tube 11 and the upper surface of the intermediate wall portion 24, as well as the tightness between the lower surface of the intermediate wall portion 24 and the upper end face of the second reaction tube 12.

[0118] Furthermore, the amount of spring 49 contraction can be adjusted by the tightening pressure of nut 51. However, if the tightening pressure of nut 51 is too high, it will hinder the extension of bellows 47. Therefore, the tightening pressure of nut 51 should also be set appropriately in consideration of the extension of bellows 47, for example, 6~50MPa.

[0119] The above describes the pressing mechanism 40 that presses the first reaction tube 11 downwards, but the pressing mechanism 40 is not limited to... Figure 5 The structure is shown. For example, the plate 43, which is the first member at one end of the fixing spring 49, can also be directly fixed relative to the first reaction tube 11. Similarly, the rod 50, which is the second member at the other end of the fixing spring 49, can also be directly fixed relative to the heating chamber 13.

[0120] Alternatively, for example, the rod 50 disposed inside the spring 49 can also be disposed outside the spring 49. In this case, by providing a plate (not shown) that connects the upper end 49b of the spring 49 to the rod 50, the upper end 49b of the spring 49 can be fixed relative to the rod 50 in a state of retraction beyond its natural length. However, from the viewpoint of reducing the number of parts and miniaturizing the pressing mechanism 40, it is preferable to dispose of the rod 50 inside the spring 49.

[0121] The mechanism for adjusting the amount of spring 49 contraction by rotating nut 51 is provided as needed, and the adjustment mechanism is not limited to the structure using nut 51.

[0122] Furthermore, the pressing mechanism 40 is not limited to a structure that presses the first reaction tube 11 downward; for example, it could also be a structure that pushes the second reaction tube 12 upward. That is, the pressing mechanism 40 only needs to have a structure that brings the first reaction tube 11 and the second reaction tube 12 relatively close together.

[0123] The CNT generation apparatus 10 of this embodiment has been described above. In this CNT generation apparatus 10, the first reaction tube 11 and the second reaction tube 12 are arranged in a straight line, and in this state, the lower end of the first reaction tube 11 and the upper end of the second reaction tube 12 are connected by a connecting retainer 20.

[0124] Therefore, by increasing the supply rate of the raw material gas to the first reaction tube 11, the raw material gas can be sufficiently heated in the second reaction tube 12 to generate CNTs. Furthermore, by making the flow path of the raw material gas longer than in the case of a single reaction tube, even when the supply rate of the raw material gas is increased, it is easier to control the processing conditions within each reaction tube 11 and 12 to be suitable for CNT generation, thus maintaining the quality of the CNTs. Therefore, the CNT generation apparatus 10 according to this embodiment can increase the amount of CNTs generated per unit time while ensuring the quality of the CNTs.

[0125] In addition, the connection retainer 20 is provided in the above embodiment, but the first reaction tube 11 and the second reaction tube 12 can also be connected without the connection retainer 20, as will be explained below.

[0126] (Other examples of join construction)

[0127] The following is for reference Figures 6-8 Other examples of connection structures are illustrated below. Figure (a) is an exploded view of the connection structure, showing the cross-section when the connection between reaction tubes 11 and 12 is cut vertically. Figure (b) shows the connection state between the first reaction tube 11 and the second reaction tube 12, showing the end face when the connection between reaction tubes 11 and 12 is cut vertically.

[0128] Figure 6 This diagram shows the connection structure of the reaction tubes 11 and 12, whose ends have been stepped. (See diagram below.) Figure 6 As shown, the lower end of the first reaction tube 11 is composed of a first outer diameter portion 11a and a cylindrical second outer diameter portion 11b with an outer diameter smaller than that of the first outer diameter portion 11a. The second outer diameter portion 11b is located below the first outer diameter portion 11a. On the other hand, the upper end of the second reaction tube 12 is composed of a first inner diameter portion 12a and a cylindrical second inner diameter portion 12b with an inner diameter smaller than that of the first inner diameter portion 12a. The second inner diameter portion 12b is located above the first inner diameter portion 12a. When connecting the first reaction tube 11 and the second reaction tube 12, the second outer diameter portion 11b is inserted inside the second inner diameter portion 12b.

[0129] An annular sealing gasket 31 is provided as a sealing element between the lower end face of the first outer diameter portion 11a and the first inner diameter portion 12a. The sealing gasket 31 is made of the same material as the sealing gasket 30 described in the above embodiment.

[0130] exist Figure 6 In the connection structure shown, since the sealing gasket 31 is not exposed to the inner circumferential surface of each reaction tube 11, 12 through which the raw material gas passes, the deterioration of the sealing gasket 31 can be suppressed. In addition, when the above-mentioned pressing mechanism 40 is applied to this connection structure, the sealing performance can be improved.

[0131] Furthermore, the outer diameter and inner diameter of the first outer diameter portion 11a and the outer diameter and inner diameter of the first inner diameter portion 12a are related to... Figure 4 Given that the outer and inner diameters of the reaction tubes 11 and 12 shown are the same, the area of ​​the sealing gasket 31 must be smaller than the area of ​​the sealing gasket 30. Therefore, from the viewpoint of sealing, a... Figure 4 The connection retainer 20 shown has excellent sealing performance.

[0132] Figure 7 Is Figure 6 The example shown is a connection structure without a sealing gasket 31. In this example, a liquid sealant is applied between the outer peripheral surface of the second outer diameter portion 11b and the inner peripheral surface of the second inner diameter portion 12b, thereby bonding the second outer diameter portion 11b and the second inner diameter portion 12b together. Therefore, Figure 7 The connection structure of the reaction tubes 11 and 12 shown has excellent sealing performance. In addition, this connection structure does not have a sealing gasket or other sealing element, so the pressing mechanism 40 mentioned above is not required, which simplifies the structure of the CNT generating device 10.

[0133] Figure 8 This diagram shows the connection structure of the reaction tubes 11 and 12, whose ends have been tapered. (See diagram below.) Figure 8 As shown, a first conical portion 11c with an outer diameter that gradually decreases downward is formed at the lower end of the first reaction tube 11, and a second conical portion 12c with an inner diameter that gradually increases upward is formed at the upper end of the second reaction tube 12.

[0134] The first reaction tube 11 and the second reaction tube 12 are connected by inserting the first conical portion 11c into the inside of the second conical portion 12c. The outer peripheral surface of the first conical portion 11c and the inner peripheral surface of the second conical portion 12c are bonded together by applying a liquid sealant. Therefore, Figure 8 The connection structure of the reaction tubes 11 and 12 shown has excellent sealing performance. In addition, this connection structure does not have a sealing gasket or other sealing element, so the pressing mechanism 40 mentioned above is not required, which simplifies the structure of the CNT generating device 10.

[0135] In addition, Figures 6-8 In the examples shown, the ends of reaction tubes 11 and 12 all require machining, but in the setup Figure 4 In the case of the connecting retainer 20 shown, end processing is not required. That is, in the connection structure using the connecting retainer 20, for example, commercially available tubes without end processing can be used directly as reaction tubes 11 and 12, which is also an advantageous structure from the point of view of cost reduction.

[0136] (Regarding the orientation of the reaction tube axis)

[0137] In the above examples, the tube axis direction of each reaction tube 11, 12 is vertical, but the tube axis direction can also be horizontal or other directions. When the tube axis direction is not vertical, for example, by replacing "the upper end of the first reaction tube 11" with "the end of the first reaction tube 11 on the side opposite to the second reaction tube 12", replacing "the lower end of the first reaction tube 11" with "the end of the first reaction tube 11 on the side of the second reaction tube 12", replacing "the upper end of the second reaction tube 12" with "the end of the second reaction tube 12 on the side of the first reaction tube 11", and replacing "the lower end of the second reaction tube 12" with "the end of the second reaction tube 12 on the side opposite to the first reaction tube 11", a CNT generating device that achieves the same effect as the CNT generating device 10 described in the above examples can be obtained.

[0138] The embodiments of the present invention have been described above, but the present invention is not limited to the examples described. Those skilled in the art will be able to conceive of various modifications or alterations within the scope of the technical concept described in the claims, which is obvious, and such modifications or alterations are naturally also considered to fall within the protection scope of the present invention.

[0139] For example, the structural elements of the above embodiments can be arbitrarily combined. Based on this arbitrary combination, the functions and effects of each structural element related to the combination can be obtained, and other functions and effects that are self-evident to those skilled in the art as described in this specification can also be obtained.

[0140] Example

[0141] In the CNT generation apparatus of an embodiment of the present invention, a performance test was performed to evaluate the airtightness of the connection between the first reaction tube and the second reaction tube.

[0142] The CNT generation apparatus of the embodiment has Figures 2-4 The structure shown depicts a first reaction tube and a second reaction tube connected by a connecting retainer. Each reaction tube is 1 m long. Additionally, sealing gaskets are provided as seals on the lower end face of the first reaction tube and the upper end face of the second reaction tube. A protective gas supply space is formed around each reaction tube, and a heater is installed within this space.

[0143] In the CNT generating apparatus constructed above, the heater temperature is set to 1200°C, and hydrogen gas, used as a carrier gas, is supplied from the upper end of the first reaction tube at a flow rate of 50 L / min. The internal pressure (gauge pressure) of the reaction tube and the hydrogen concentration in the protective gas supply space are measured at this time to evaluate the airtightness of the reaction tube.

[0144] In addition, as a conventional CNT device, a performance test was conducted under the same temperature and gas supply conditions as the embodiment in a device in which a 2m reaction tube is provided instead of the first reaction tube, the second reaction tube and the connecting retainer described above.

[0145] The results of the above performance tests show that in both the CNT apparatus of the embodiments and the CNT apparatus of the comparative examples, the internal pressure of the reaction tube is 0~2 kPaG, and the hydrogen concentration in the protective gas supply space is 0 ppm. That is, even the CNT generating apparatus with the first and second reaction tubes connected together has the same airtightness as the existing single-tube CNT generating apparatus, and can perform CNT generation processing.

[0146] Furthermore, the effects described in this specification are merely illustrative or exemplary and not limiting. That is to say, the technology disclosed herein can achieve the aforementioned effects and other effects that are self-evident to those skilled in the art based on the description in this specification, or substitute for the aforementioned effects to achieve other effects that are self-evident to those skilled in the art based on the description in this specification.

[0147] Industrial availability

[0148] This invention can be applied to devices for generating carbon nanotubes.

[0149] Explanation of reference numerals in the attached figures

[0150] 1. CNT manufacturing apparatus (carbon nanotube manufacturing apparatus); 10. CNT generation apparatus (carbon nanotube generation apparatus); 11. First reaction tube; 12. Second reaction tube; 13. Heating chamber; 13a. Top wall; 13b. Through hole; 14. Insulation material; 15. Space; 16. Heater; 17. Thermocouple; 18. Protective gas supply pipe; 19. Exhaust pipe; 20. Connecting and retaining member; 21. Side wall; 22. First insertion port; 23. Second insertion port ; 24. Intermediate wall section; 25. Through hole; 30. Sealing gasket; 40. Pressing mechanism; 41. Plate; 42. Plate; 43. Plate; 44. Plate; 45. Cylindrical wall section; 46. Plate; 47. Bellows; 48. Space; 49. Spring; 49a. Lower end of spring; 49b. Upper end of spring; 50. Rod; 51. Nut; 60. CNT recycling device (carbon nanotube recycling device); 61. Recycling chamber; 62. Roller; 63. Motor.

Claims

1. A carbon nanotube generating apparatus, wherein, This carbon nanotube generation device has the following features: The first reaction tube is supplied with the raw material gas for the carbon nanotubes; The second reaction tube through which the raw material gas passes; and A heating chamber that heats the first reaction tube and the second reaction tube. The first reaction tube and the second reaction tube are arranged in a straight line. The end of the first reaction tube is connected to the end of the second reaction tube.

2. The carbon nanotube generation apparatus according to claim 1, wherein, The carbon nanotube generating apparatus includes a connecting member that connects the end of the first reaction tube and the end of the second reaction tube. The connecting member has a first insertion port for inserting the end of the first reaction tube, a second insertion port for inserting the end of the second reaction tube, and an intermediate wall portion disposed between the first insertion port and the second insertion port. The intermediate wall portion has a first surface facing and parallel to the end face of the first reaction tube, a second surface facing and parallel to the end face of the second reaction tube, and a through hole extending along the tube axis of the first reaction tube.

3. The carbon nanotube generation apparatus according to claim 2, wherein, A sealing element is provided between one or both of the end face of the first reaction tube and the intermediate wall portion and between the end face of the second reaction tube and the intermediate wall portion.

4. The carbon nanotube generation apparatus according to claim 1, wherein, The end of the first reaction tube on the second reaction tube side has a first outer diameter portion and a cylindrical second outer diameter portion with an outer diameter smaller than the first outer diameter portion. The end of the second reaction tube on the first reaction tube side has a first inner diameter portion and a cylindrical second inner diameter portion with an inner diameter larger than the first inner diameter portion. The second outer diameter portion is inserted into the inside of the second inner diameter portion.

5. The carbon nanotube generation apparatus according to claim 4, wherein, A sealing element is provided between the end face of the first outer diameter portion and the end face of the second inner diameter portion.

6. The carbon nanotube generation apparatus according to claim 3, wherein, The seal is made of graphite.

7. The carbon nanotube generation apparatus according to claim 3, wherein, The carbon nanotube generating device has a pressing mechanism that brings the first reaction tube and the second reaction tube relatively close together and seals them together through the sealing element.

8. The carbon nanotube generation apparatus according to claim 7, wherein, The end of the first reaction tube opposite to the side of the second reaction tube is located outside the heating chamber. The pressing mechanism has: A spring that extends and retracts in a direction parallel to the axis of the first reaction tube; The first component, which has one end of the spring fixed thereon; and The second component has the other end of the spring fixed to it. The first component is fixed relative to the first reaction tube. The second component is fixed relative to the heating chamber. The spring is fixed to the second member in a state of contraction compared to its natural length in a region opposite to the region on the side of the second reaction tube, relative to the first member.

9. The carbon nanotube generating apparatus according to claim 8, wherein, The second component is a rod that passes through the inside of the spring.

10. The carbon nanotube generation apparatus according to claim 8, wherein, The carbon nanotube generating device has an adjustment mechanism for adjusting the amount of contraction of the spring.

11. The carbon nanotube generating apparatus according to claim 9, wherein, The bar has an external threaded portion. A nut is installed on the external threaded portion. The spring is disposed between the nut and the first member. The carbon nanotube generating device has a structure that allows the amount of spring contraction to be adjusted by rotating the nut.

12. The carbon nanotube generation apparatus according to claim 1, wherein, The arithmetic mean roughness Ra of the end face of the first reaction tube and the end face of the second reaction tube at the connection between the first reaction tube and the second reaction tube is 0.2 μm to 6.3 μm.

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