Method for regenerating carbon fiber bundles and apparatus for regenerating carbon fiber bundles

Abstract

To provide a regeneration method of a carbon fiber bundle and a regenerator of a carbon fiber bundle, capable of heating an intermediate carbon fiber bundle and stably and efficiently decomposing a decomposition residue of a matrix resin.SOLUTION: A regeneration method of a carbon fiber bundle includes: a first heating step of heating a high-pressure hydrogen tank to decompose part of a matrix resin; a rolling-out step of rolling out an intermediate carbon fiber bundle with a decomposition residue of the matrix resin adhered thereto from a carbon fiber-reinforced resin layer that decomposes part of the matrix resin; a second heating step of heating the rolled-out intermediate carbon fiber bundle I using a tubular furnace 40 and decomposing a decomposition residue of the matrix resin to obtain a regenerated carbon fiber bundle R; and a winding-up step of winding up the regenerated carbon fiber bundle R. The tubular furnace 40 includes: a heating wire heater 43 configured to heat the intermediate carbon fiber bundle I; and a heat insulation lid 42 disposed at an inlet and an outlet and have a slit-like through hole that allows a passage of the intermediate carbon fiber bundle I.SELECTED DRAWING: Figure 5

Description

【Technical Field】 【0001】 The present invention relates to a method for recycling carbon fiber bundles and a device for recycling carbon fiber bundles. 【Background Art】 【0002】 In recent years, efforts to significantly reduce the generation of waste have been actively carried out through waste prevention, reduction, recycling, and reuse. Toward this realization, research and development on methods for recovering carbon fibers from carbon fiber reinforced resins have been conducted. 【0003】 Patent Document 1 describes a method for recycling carbon fibers, including a step of thermally decomposing the resin in a carbon fiber reinforced resin molded product by a first heat treatment, and a step of pulling out and winding up the carbon fibers from the carbon fiber reinforced resin molded product after the first heat treatment. At this time, the winding-up step includes a step of thermally decomposing the resin residue adhering to the carbon fibers by a second heat treatment, and a step of applying a sizing agent to the carbon fibers after the second heat treatment. Further, the carbon fiber reinforced resin molded product is a tank including a liner and a carbon fiber reinforced resin layer. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2022 - 15366 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 However, when using the carbon fiber recycling method of Patent Document 1, when thermally decomposing the resin residue adhering to the carbon fibers by a second heat treatment, heat energy is released or outside air is mixed in. Therefore, it is difficult to stably and efficiently thermally decompose the resin residue adhering to the carbon fibers. 【0006】 The present invention aims to provide a method and apparatus for regenerating carbon fiber bundles that can stably and efficiently decompose the decomposition residue of the matrix resin by heating the intermediate carbon fiber bundles. [Means for solving the problem] 【0007】 (1) A method for regenerating carbon fiber bundles from a structure having a hollow substrate and a carbon fiber reinforced resin layer containing a carbon fiber bundle and matrix resin wound around the hollow substrate, comprising: a first heating step of heating the structure to decompose a portion of the matrix resin; an unwinding step of unwinding an intermediate carbon fiber bundle to which the decomposition residue of the matrix resin is attached from the carbon fiber reinforced resin layer from which a portion of the matrix resin has been decomposed; a second heating step of obtaining a regenerated carbon fiber bundle by heating the unwinding intermediate carbon fiber bundle using a tubular furnace to decompose the decomposition residue of the matrix resin; and a winding step of winding up the regenerated carbon fiber bundle, wherein the tubular furnace comprises a heater for heating the intermediate carbon fiber bundle and a lid installed at the inlet and outlet, through which the intermediate carbon fiber bundle can pass. 【0008】 (2) The method for regenerating a carbon fiber bundle according to (1), wherein the tubular furnace has a heating region in which the intermediate carbon fiber bundle is heated and a non-heating region in which the intermediate carbon fiber bundle is not heated, and the non-heating region is located between the heating region and the inlet and / or between the heating region and the outlet. 【0009】 (3) The method for regenerating a carbon fiber bundle according to (2), wherein the tubular furnace further comprises an introduction tube for introducing an oxidizing gas into the heating region. 【0010】 (4) The method for regenerating a carbon fiber bundle according to (3), wherein the oxidizing gas is introduced along the surface of the intermediate carbon fiber bundle. 【0011】 (5) The method for regenerating a carbon fiber bundle according to (3) or (4), wherein the oxidizing gas is introduced from the downstream side to the upstream side of the tubular furnace. 【0012】 (6) The method for regenerating a carbon fiber bundle according to any one of (3) to (5), wherein the introduction pipe is arranged such that the oxidizing gas introduced into the heating region forms turbulence. 【0013】 (7) The method for regenerating a carbon fiber bundle according to any one of (1) to (6), wherein the through hole is slit-shaped and formed in the horizontal direction. 【0014】 (8) The method for regenerating a carbon fiber bundle according to any one of (1) to (7), wherein the lid has a plurality of through holes formed therein. 【0015】 (9) A carbon fiber bundle regeneration apparatus having a hollow substrate and a carbon fiber reinforced resin layer containing a carbon fiber bundle and matrix resin wound around the hollow substrate, comprising: a first heating section that heats the structure to decompose a portion of the matrix resin; an unwinding section that unwinds an intermediate carbon fiber bundle to which the decomposition residue of the matrix resin is attached from the carbon fiber reinforced resin layer from which a portion of the matrix resin has been decomposed; a second heating section that heats the unwinded intermediate carbon fiber bundle to decompose the decomposition residue of the matrix resin to obtain a regenerated carbon fiber bundle; and a winding section that winds up the regenerated carbon fiber bundle, wherein the second heating section is a tubular furnace having a heater for heating the intermediate carbon fiber bundle and a lid installed at the inlet and outlet, through which the intermediate carbon fiber bundle can pass. [Effects of the Invention] 【0016】 According to the present invention, it is possible to provide a method and apparatus for regenerating carbon fiber bundles that can stably and efficiently decompose the decomposition residue of the matrix resin by heating the intermediate carbon fiber bundle. [Brief explanation of the drawing] 【0017】 [Figure 1] It is a cross-sectional view showing an example of a high-pressure hydrogen tank. [Figure 2] It is a view showing an example of the first heating part used in the first heating step. [Figure 3] It is a view showing a rotating part for rotating the high-pressure hydrogen tank in the heat treatment chamber of FIG. 2. [Figure 4] It is a view showing an example of the unwinding part used in the unwinding step. [Figure 5] It is a schematic view showing an example of the second heating part, sizing part and winding part used in the second heating step, sizing step and winding step. [Figure 6] It is a front view showing the heat insulation cover of FIG. 5. [Figure 7] It is a front view showing a modified example of the heat insulation cover of FIG. 6. [Figure 8] It is a partially enlarged cross-sectional view of the tubular furnace of FIG. 5. 【Mode for Carrying Out the Invention】 【0018】 Hereinafter, embodiments of the present invention will be described with reference to the drawings. 【0019】 A method for regenerating a carbon fiber bundle according to an embodiment of the present invention is a method for regenerating a carbon fiber bundle from a structure having a hollow base material, a carbon fiber bundle wound around the hollow base material, and a carbon fiber reinforced resin layer containing a matrix resin. The structure is not particularly limited, and examples thereof include known high-pressure hydrogen tanks (types 2 to 4). 【0020】 The carbon fibers constituting the carbon fiber bundle are not particularly limited, and examples thereof include polyacrylonitrile (PAN)-based carbon fibers and pitch-based carbon fibers. Here, the carbon fibers constituting the carbon fiber bundle are long fibers. The fiber length of the carbon fibers is not particularly limited, but is, for example, 1 m or more. The matrix resin is not particularly limited, and examples thereof include thermosetting resins such as epoxy resins and thermoplastic resins. 【0021】 Figure 1 shows an example of a high-pressure hydrogen tank. 【0022】 The high-pressure hydrogen tank T comprises a liner L as a hollow base material, a carbon fiber reinforced resin layer F containing a carbon fiber bundle and matrix resin wrapped around the liner L, and nozzles C1 and C2 installed at both ends in the longitudinal direction. The material constituting the liner L is not particularly limited, but examples include metals such as aluminum and chromium-molybdenum steel, and resins such as polyamide and polyethylene. 【0023】 The method for manufacturing the high-pressure hydrogen tank T is not particularly limited, but one example is the filament winding method. 【0024】 A carbon fiber bundle regeneration method according to one embodiment of the present invention includes a first heating step of heating a high-pressure hydrogen tank T to decompose a portion of the matrix resin, and an unwinding step of unwinding an intermediate carbon fiber bundle I to which matrix resin decomposition residue is attached from the carbon fiber reinforced resin layer from which a portion of the matrix resin has been decomposed. Furthermore, a carbon fiber bundle regeneration method according to one embodiment of the present invention further includes a second heating step of heating the unwinding intermediate carbon fiber bundle I using a tubular furnace to decompose matrix resin decomposition residue and thereby obtain a regenerated carbon fiber bundle R, and a winding step of winding up the regenerated carbon fiber bundle R. Here, the tubular furnace has a heater for heating the intermediate carbon fiber bundle I, and a lid installed at the inlet and outlet, through which the intermediate carbon fiber bundle I can pass. Therefore, when the intermediate carbon fiber bundle I is heated using the tubular furnace to decompose matrix resin decomposition residue, the release of thermal energy and the mixing of outside air are suppressed, and as a result, matrix resin decomposition residue is decomposed stably and efficiently. 【0025】 The first heating step preferably includes a first step of decomposing the matrix resin at a temperature above the thermal decomposition initiation temperature of the matrix resin and below the flash point of the thermal decomposition gas of the matrix resin, and a second step of decomposing the matrix resin decomposed in the first step at a temperature above the thermal oxidative decomposition initiation temperature of the matrix resin decomposition residue and below the thermal decomposition initiation temperature of the carbon fibers. This suppresses overheating due to combustion of the thermal decomposition gas of the matrix resin and deterioration of the carbon fibers. 【0026】 When the matrix resin is an epoxy resin, for example, in the first step, heating is performed at a temperature of 330°C to 360°C, and in the second step, heating is performed at a temperature of 430°C to 470°C. In this case, examples of pyrolysis gases include bisphenol A and phenol. 【0027】 Furthermore, the heating temperature in the first heating step is not particularly limited, as long as it is possible to unwind the carbon fiber bundles on which the decomposition residue of the matrix resin is attached. 【0028】 Figure 2 shows a heat treatment furnace as an example of the first heating section used in the first heating process. 【0029】 The heat treatment furnace 10 has a heat treatment chamber 11 and a combustion chamber 12. 【0030】 The heat treatment chamber 11 is a sealed space surrounded by an outer wall 11a and an inner wall 11b. In addition, burners 11c are installed in the heat treatment chamber 11 at the top of the left outer wall 11a and at the bottom of the right outer wall 11a, so that combustion gases flow into the inner wall 11b. Therefore, when gas fuel and air are mixed and burned in the burners 11c, the combustion gases circulate within the inner wall 11b, and the temperature inside the inner wall 11b stabilizes. 【0031】 The heat treatment chamber 11 has sealing doors installed on a portion of the outer wall 11a and inner wall 11b to accommodate the high-pressure hydrogen tank T. Here, the high-pressure hydrogen tank T is placed on an insulating material 11d that penetrates the bottom surface of the inner wall 11b. A load cell 11e, which acts as a mass detection unit, is installed between the bottom surface of the outer wall 11a and the insulating material 11d, and detects the mass of the high-pressure hydrogen tank T in real time based on the amount of strain. As a result, the heating conditions in the heat treatment chamber 11 are optimized, so fluctuations in the amount of decomposition of the matrix resin due to individual differences in the materials and shape of the high-pressure hydrogen tank T are suppressed, and the accuracy of control is improved. In addition, since the heating time in the heat treatment chamber 11 does not need to be longer than necessary, it contributes to shortening the heating time and reducing energy consumption. 【0032】 The mass detection unit may also detect the decrease in mass of the high-pressure hydrogen tank T in real time. Furthermore, the mass detection unit may be omitted if necessary. 【0033】 The decomposition gas of the matrix resin generated within the inner wall 11b is discharged from the exhaust port 11f formed at the top of the inner wall 11b in the figure, and then introduced into the combustion chamber 12 via the piping 11g installed through the outer wall 11a. 【0034】 The combustion chamber 12 is a sealed space surrounded by an outer wall 12a and an inner wall 12b. In the combustion chamber 12, a burner 12c is installed in the center of the left outer wall 12a in the figure, so that combustion gases flow into the inner wall 12b. Meanwhile, the piping 11g penetrates the outer wall 12a, then penetrates both the inside and outside of the inner wall 12b within the outer wall 12a, and finally connects to the upper left part of the inner wall 12b in the figure. At this time, the decomposition gas of the matrix resin is heated by the combustion gases flowing within the inner wall 12b while passing through the piping 11g inside the inner wall 12b, and then introduced from the upper left part of the inner wall 12b and comes into contact with the combustion gases. As a result, the decomposition gas of the matrix resin is burned and then exhausted to the outside through the exhaust port 12d. 【0035】 Figure 3 shows an example of a rotating mechanism that rotates the high-pressure hydrogen tank T within the heat treatment chamber 11. Figures 3(a) and 3(b) are a cross-sectional view and a side view, respectively. 【0036】 Since the rotating part 20 has a rotation axis 21 that is roughly horizontal and penetrates the wall W of the heat treatment chamber 11, the temperature distribution of the carbon fiber reinforced resin layer F in the vertical direction is made uniform in the figure. 【0037】 The rotation axis 21 may be in a direction other than substantially horizontal, for example, it may be substantially vertical. When the rotation axis 21 is substantially vertical, the temperature distribution of the carbon fiber reinforced resin layer F in the heat treatment chamber 11 is made uniform to a degree similar to when the rotation axis 21 is substantially horizontal. 【0038】 The high-pressure hydrogen tank T is connected to the rotating shaft 21 via a flanged jig 22 and a rotating shaft flange 23 that utilize the shapes of the nozzles C1 and C2. The flanged jig 22 and the rotating shaft flange 23 are fixed together, for example, with bolts and nuts. The high-pressure hydrogen tank T is placed on a base 24, on which bearings 25 are installed. Furthermore, an insulating material 26 is installed inside the wall W of the heat treatment furnace 10. On the outside of the wall W of the heat treatment furnace 10, a motor is installed to rotate the rotating shaft 21, and a cooling jacket 27 is installed around the rotating shaft 21. 【0039】 Figure 4 shows an example of a winding section used in the winding process. Figures 4(a) and 4(b) are a front view and a side view, respectively. 【0040】 The unwinding section 30 includes a rotating jig 31 that rotatably supports the high-pressure hydrogen tank T1, from which a portion of the matrix resin has decomposed, and a motor 32 that rotates the high-pressure hydrogen tank T1. The rotational power of the motor 32 is transmitted to the rotating jig 31 via a belt 33. As a result, the intermediate carbon fiber bundle I is unwound via rollers 34, 35, and 36. At this time, the roller 34 is positioned so that the intermediate carbon fiber bundle I is unwound outside the tangent to the position where the intermediate carbon fiber bundle I is unwound from the high-pressure hydrogen tank T1. Furthermore, the rollers 34, 35, and 36 have long axes to correspond to the unwinding of the intermediate carbon fiber bundle I in the longitudinal direction of the high-pressure hydrogen tank T1. In addition, a dancer roller 37 is installed to control the unwinding tension in order to absorb the difference in the amount of unwinding per rotation due to hoop winding and helical winding of the intermediate carbon fiber bundle I. 【0041】 Alternatively, a blade may be installed instead of the roller 34. 【0042】 The heating temperature in the second heating step is preferably higher than or equal to the heating temperature in the first heating step. This facilitates the decomposition of matrix resin residues attached to the intermediate carbon fiber bundle I. On the other hand, the heating temperature in the second heating step is preferably lower than or equal to the thermal decomposition start temperature of the carbon fibers. This suppresses the degradation of the carbon fibers. 【0043】 Alternatively, after performing a sizing process to size the recycled carbon fiber bundles R, the sized recycled carbon fiber bundles R may be wound up. 【0044】 Figure 5 shows an example of the second heating section, sizing section, and winding section used in the second heating process, sizing process, and winding process. 【0045】 The tubular furnace 40, which serves as the second heating section, is equipped with an insulating lid 42 (see Figure 6) at its inlet and outlet, i.e., at both ends of the quartz tube 41. The lid 42 has slit-shaped through-holes S through which the intermediate carbon fiber bundle I, to which the decomposition residue of the matrix resin is attached, can pass. Here, the slit-shaped through-holes S are formed horizontally. The tubular furnace 40 also has an electric heating element 43, an insulating material 44, and a protective cover 45 sequentially installed in the center of the quartz tube 41. As a result, the electric heating element 43 heats the intermediate carbon fiber bundle I, decomposing the decomposition residue of the matrix resin, thereby obtaining a recycled carbon fiber bundle R. 【0046】 When heating multiple intermediate carbon fiber bundles I, an insulating lid 42A (see Figure 7) with multiple slit-shaped through holes S can be used. Furthermore, the shape of the through holes formed in the insulating lid is not limited to slits, as long as the intermediate carbon fiber bundles I can pass through. 【0047】 As shown in Figure 8, the tubular furnace 40 has a heating region H in which the intermediate carbon fiber bundle I is heated, and an unheated region N in which the intermediate carbon fiber bundle I is not heated. Specifically, the quartz tube 41 constituting the heating region H has an electric heating wire heater 43 wrapped around it, while the quartz tube 41 constituting the unheated region N does not have an electric heating wire heater 43 wrapped around it. Here, the unheated region N exists between the inlet end of the quartz tube 41 and the heating region H, and between the outlet end of the quartz tube 41 and the heating region H. As a result, the temperature difference between the heating region H and the unheated region N generates a natural convection vortex, and consequently, the atmospheric gas in the heating region H accumulates. 【0048】 The tubular furnace 40 is equipped with an introduction pipe 46 for introducing an oxidizing gas into the heating region H. By introducing a minimum amount of oxidizing gas, carbon dioxide contained in the atmospheric gas in the stagnant heating region H is discharged, thereby maintaining the composition and temperature of the atmospheric gas in the heating region H. The oxidizing gas is also introduced along the surface of the intermediate carbon fiber bundle I. This suppresses the fuzzing of the recycled carbon fiber bundle R. Furthermore, the oxidizing gas is introduced from the downstream side to the upstream side of the tubular furnace 40. This makes it easier to decompose trace amounts of matrix resin decomposition residue attached to the intermediate carbon fiber bundle I on the downstream side of the tubular furnace 40. The introduction pipe 46 is also positioned along the upper surface of the quartz tube 41. As a result, the oxidizing gas introduced into the heating region H forms turbulence. In order for the oxidizing gas introduced into the heating region H to form turbulence, the temperature of the oxidizing gas may be set to room temperature, or the oxidizing gas may be introduced intermittently. 【0049】 The oxidizing gas is not particularly limited as long as it is a gas that promotes the oxidation of the decomposition residue of the matrix resin attached to the intermediate carbon fiber bundle I, but an example is oxygen. 【0050】 The heating region H may be divided into multiple regions. Also, the inlet tube 46 does not have to be positioned along the upper surface of the quartz tube 41. 【0051】 The sizing unit 50 passes the recycled carbon fiber bundle R through the sizing liquid 51. At this time, the heater 52 heats the sizing liquid 51. In addition, the roller 53 prevents excessive application of the sizing liquid 51 to the recycled carbon fiber bundle R. 【0052】 If necessary, a drying oven may be installed to dry the recycled carbon fiber bundles R. 【0053】 The feeding mechanism 60 has feeder rollers 61, 62, and 63, and the friction between the feeder rollers 61, 62, and 63 and the recycled carbon fiber bundle R is used to control the linear speed of the recycled carbon fiber bundle R to a linear speed that is easy to manage in the process. 【0054】 The winding unit 70 includes a winding motor 71 for winding the recycled carbon fiber bundle R onto the paper core P, and a slide roller 72 for traverse winding the recycled carbon fiber bundle R. At this time, the winding tension of the recycled carbon fiber bundle R is controlled by controlling the torque of the winding motor 71. 【0055】 Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and the above embodiments may be modified as appropriate within the scope of the spirit of the present invention. For example, as structures other than the high-pressure hydrogen tank, a propeller shaft, a safety block, a low-friction roll, a spindle shaft, a motor rotor, etc. may be used. [Explanation of Symbols] 【0056】 40 tube furnace 42, 42A Insulated cover 43. Electric heating element heater 46 Introductory tube C1, C2 nozzles F Carbon fiber reinforced resin layer H heating area I. Intermediate carbon fiber bundle L Liner N Non-heated area R Recycled carbon fiber bundle S-shaped through hole T, T1 High-Pressure Hydrogen Tank

Claims

[Claim 1] A method for regenerating carbon fiber bundles from a structure having a hollow substrate and a carbon fiber reinforced resin layer containing a carbon fiber bundle and matrix resin wrapped around the hollow substrate, A first heating step involves heating the structure to decompose a portion of the matrix resin, A winding step in which an intermediate carbon fiber bundle to which decomposition residue of the matrix resin is attached is wound from a carbon fiber reinforced resin layer in which a portion of the matrix resin has decomposed, A second heating step involves using a tubular furnace to heat the unwound intermediate carbon fiber bundle and decompose the decomposition residue of the matrix resin to obtain a regenerated carbon fiber bundle. The process includes winding the recycled carbon fiber bundle, The tubular furnace comprises a heater for heating the intermediate carbon fiber bundle, and a lid installed at the inlet and outlet, through which the intermediate carbon fiber bundle can pass. The tubular furnace has a heating region in which the intermediate carbon fiber bundle is heated, and a non-heating region in which the intermediate carbon fiber bundle is not heated. The unheated region is located between the heated region and the inlet and / or between the heated region and the outlet. The tubular furnace further includes an introduction tube for introducing an oxidizing gas into the heating region, A method for regenerating a carbon fiber bundle, wherein the oxidizing gas is introduced along the surface of the intermediate carbon fiber bundle. [Claim 2] A method for regenerating carbon fiber bundles from a structure having a hollow substrate and a carbon fiber reinforced resin layer containing a carbon fiber bundle and matrix resin wrapped around the hollow substrate, A first heating step involves heating the structure to decompose a portion of the matrix resin, A winding step in which an intermediate carbon fiber bundle to which decomposition residue of the matrix resin is attached is wound from a carbon fiber reinforced resin layer in which a portion of the matrix resin has decomposed, A second heating step involves using a tubular furnace to heat the unwound intermediate carbon fiber bundle and decompose the decomposition residue of the matrix resin to obtain a regenerated carbon fiber bundle. The process includes winding the recycled carbon fiber bundle, The tubular furnace comprises a heater for heating the intermediate carbon fiber bundle, and a lid installed at the inlet and outlet, through which the intermediate carbon fiber bundle can pass. The tubular furnace has a heating region in which the intermediate carbon fiber bundle is heated, and a non-heating region in which the intermediate carbon fiber bundle is not heated. The unheated region is located between the heated region and the inlet and / or between the heated region and the outlet. The tubular furnace further includes an introduction tube for introducing an oxidizing gas into the heating region, A method for regenerating carbon fiber bundles, wherein the oxidizing gas is introduced from the downstream side to the upstream side of the tubular furnace. [Claim 3] The method for regenerating a carbon fiber bundle according to claim 1 or 2, wherein the introduction pipe is arranged such that the oxidizing gas introduced into the heating region forms turbulence. [Claim 4] The method for regenerating a carbon fiber bundle according to claim 1 or 2, wherein the through-hole is slit-shaped and formed in the horizontal direction. [Claim 5] The method for regenerating a carbon fiber bundle according to claim 1 or 2, wherein the lid has a plurality of through holes formed therein. [Claim 6] An apparatus for regenerating carbon fiber bundles from a structure having a hollow substrate and a carbon fiber reinforced resin layer containing a carbon fiber bundle and matrix resin wrapped around the hollow substrate, A first heating unit that heats the structure to decompose a portion of the matrix resin, A winding section for winding an intermediate carbon fiber bundle to which decomposition residues of the matrix resin are attached, from a carbon fiber reinforced resin layer in which a portion of the matrix resin has decomposed, A second heating unit that heats the unwound intermediate carbon fiber bundle to decompose the decomposition residue of the matrix resin, thereby obtaining a regenerated carbon fiber bundle, It has a winding section for winding the recycled carbon fiber bundle, The second heating section is a tubular furnace having a heater for heating the intermediate carbon fiber bundle and a lid installed at the inlet and outlet, the lid having through holes through which the intermediate carbon fiber bundle can pass. The tubular furnace has a heating region in which the intermediate carbon fiber bundle is heated, and a non-heating region in which the intermediate carbon fiber bundle is not heated. The unheated region is located between the heated region and the inlet and / or between the heated region and the outlet. The tubular furnace further includes an introduction tube for introducing an oxidizing gas into the heating region, The oxidizing gas is introduced along the surface of the intermediate carbon fiber bundle in a carbon fiber bundle regeneration device. [Claim 7] An apparatus for regenerating carbon fiber bundles from a structure having a hollow substrate and a carbon fiber reinforced resin layer containing a carbon fiber bundle and matrix resin wrapped around the hollow substrate, A first heating unit that heats the structure to decompose a portion of the matrix resin, A winding section for winding an intermediate carbon fiber bundle to which decomposition residues of the matrix resin are attached, from a carbon fiber reinforced resin layer in which a portion of the matrix resin has decomposed, A second heating unit that heats the unwound intermediate carbon fiber bundle to decompose the decomposition residue of the matrix resin, thereby obtaining a regenerated carbon fiber bundle, It has a winding section for winding the recycled carbon fiber bundle, The second heating section is a tubular furnace having a heater for heating the intermediate carbon fiber bundle and a lid installed at the inlet and outlet, the lid having through holes through which the intermediate carbon fiber bundle can pass. The tubular furnace has a heating region in which the intermediate carbon fiber bundle is heated, and a non-heating region in which the intermediate carbon fiber bundle is not heated. The unheated region is located between the heated region and the inlet and / or between the heated region and the outlet. The tubular furnace further includes an introduction tube for introducing an oxidizing gas into the heating region, The oxidizing gas is introduced from the downstream side to the upstream side of the tubular furnace in a carbon fiber bundle regeneration device.

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