Heat accumulating focusing fixed bed reactor for carbon nanotube production

Abstract

This invention provides a regenerative focusing fixed-bed reactor for carbon nanotube preparation, comprising a furnace body, a furnace chamber, and a control center. The furnace body is fitted outside the furnace chamber, and the control center is connected to the furnace chamber. The furnace body includes an outer shell module and a heat insulation module. The furnace chamber includes a focusing cavity module, a composite heat source module, a gas passage module, and a material reaction module. The control center includes a temperature sensing module, a main control module, a power adjustment module, and a display module. The focusing cavity module includes a cavity shell unit and an inner lining reflector unit. The composite heat source module includes a heat storage unit, an electric heating unit, and a conductive unit. The material reaction module includes a furnace tube unit, a sample carrying unit, and a support unit. The electric heating unit heats the heat storage unit, and the radiation from the heat storage unit is reflected by the inner lining reflector unit and focused onto the furnace tube unit. The temperature sensing module detects the temperature of the furnace tube unit and transmits it to the main control module, and the power adjustment module adjusts the power of the electric heating unit. This invention solves the problem of heating power fluctuations affecting carbon nanotube growth.

Description

Technical Field

[0001] This invention relates to the field of carbon nanotube preparation technology, and more particularly to a regenerative focusing fixed-bed reactor for carbon nanotube preparation. Background Technology

[0002] Carbon nanotubes, due to their excellent mechanical, electrical, and thermal properties, have broad application prospects in composite materials, electronic devices, and energy storage materials, and have become one of the hot topics in nanomaterials research. Currently, the preparation of carbon nanotubes mainly relies on chemical vapor deposition, among which fixed-bed reactors are widely used in the production and research of carbon nanotubes due to their advantages such as simple structure, convenient operation, and low cost.

[0003] However, the growth process of carbon nanotubes is extremely sensitive to temperature, and the temperature stability of the growth region directly determines key quality indicators such as the diameter, length, purity, and degree of graphitization of the carbon nanotubes. In existing fixed-bed reactors, resistance wires are commonly used as heating elements. The heating mode is as follows: the furnace temperature is monitored in real time by a temperature sensor. When the temperature reaches the set value, the control system cuts off the power to the resistance wire to stop heating; after the temperature drops to the set lower limit, the power is turned on again to resume heating. This intermittent "on-off" control mode causes the temperature of the resistance wire itself to fluctuate drastically during the heating and stopping cycles, which is then directly transferred to the reactor tubes through thermal radiation and heat conduction, making it difficult to obtain a continuous and stable temperature field in the carbon nanotube growth region.

[0004] Temperature instability can cause fluctuations in catalyst activity and uneven carbon source cracking rates, leading to uneven carbon nanotube growth, increased defects, and decreased yield, severely restricting the controllable preparation of high-quality carbon nanotubes. To compensate for these fluctuations, existing technologies often rely on more complex PID feedback control or more frequent on / off switching. Some reactors have also attempted to incorporate insulation layers to reduce heat loss, but none of these methods include a dedicated heat storage buffer structure. Therefore, they cannot fundamentally eliminate the drastic fluctuations in the radiated energy of the resistance wire itself, and the reaction zone still experiences radiated energy disturbances at the same frequency as the heating power.

[0005] Meanwhile, existing reactors mostly use direct radiation heating from a single heat source, which has low heat utilization efficiency, high energy consumption, and lacks a precise energy-concentrating mechanism, making it difficult to form a stable high-temperature focusing area in the furnace tube, resulting in poor temperature field uniformity in the reaction zone.

[0006] In summary, the goal is to develop a fixed-bed reactor that combines heat storage and buffering with heat focusing functions to address the problems of unstable temperature, high energy consumption, and uneven product quality in the existing carbon nanotube preparation process. Summary of the Invention

[0007] This invention provides a regenerative focusing fixed-bed reactor for carbon nanotube preparation, to solve the problem of heating power fluctuations affecting the growth stability of carbon nanotubes in prior art.

[0008] To solve the above-mentioned technical problems, the present invention is implemented as follows: This invention provides a regenerative focusing fixed-bed reactor for carbon nanotube preparation, used to absorb and stabilize the influence of heating power fluctuations on the carbon nanotube growth region, including a furnace body, a furnace chamber, and a control center; the furnace body is fitted outside the furnace chamber, and the control center is connected to the furnace chamber.

[0009] The furnace body includes an outer shell module and a heat preservation module; the furnace chamber includes an energy-concentrating cavity module, a composite heat source module, a gas passage module, and a material reaction module; the control center includes a temperature sensing module, a main control module, a power adjustment module, and a display module; the energy-concentrating cavity module includes a cavity shell unit and an inner lining reflection unit; the composite heat source module includes a heat storage unit, an electric heating unit, and a conductive unit; the gas passage module includes an inlet unit, an outlet unit, a furnace plug unit, and a sealing unit; the material reaction module includes a furnace tube unit, a sample carrying unit, and a support unit.

[0010] The composite heat source module generates energy through the electric heating unit, which raises and stabilizes the temperature of the heat storage unit; the radiant energy emitted by the heat storage unit is reflected by the inner lining reflector and focused onto the furnace tube unit; the temperature sensing module detects the temperature of the furnace tube unit in real time and transmits the temperature signal to the main control module; the main control module adjusts the power of the electric heating unit through the power adjustment module according to the deviation between the set temperature and the detected temperature.

[0011] The cross-section of the energy-concentrating cavity module is a bilaterally symmetrical double-elliptical composite surface, including a first ellipse and a second ellipse; the foci of the first ellipse include foci F1 and foci O, and the foci of the second ellipse include foci F2 and foci O, and the first ellipse and the second ellipse share the same foci O; the composite heat source module is simultaneously located at foci F1 and foci F2, and the material reaction module is located at foci O.

[0012] The first ellipse receives radiant energy emitted from the composite heat source module located at focal point F1, which is reflected by the inner wall of the double elliptical composite surface and converges at the common focal point O. Similarly, the second ellipse receives radiant energy emitted from the composite heat source module located at focal point F2, which is also reflected by the inner wall of the double elliptical composite surface and converges at focal point O. Through the symmetrical structure of the double elliptical composite surface, dual focusing heating of the furnace tube unit from two different directions is achieved, ensuring efficient superposition of radiant energy at focal point O. This results in a stable and uniform banded temperature zone formed in the furnace tube unit at focal point O within a certain axial range, ensuring consistent heating of the catalyst during carbon nanotube growth and resulting in a narrower distribution of carbon nanotube growth length.

[0013] The inner lining reflective unit is a high infrared reflective coating applied to the inner wall of the cavity shell unit, used to focus the radiant energy of the heat storage unit onto the furnace tube unit.

[0014] The gas inside the furnace tube unit is supplied by the gas passage module, while the gas between the cavity shell unit and the furnace tube unit is in communication with the external environment.

[0015] The heat storage unit is made of a material with high heat capacity and high infrared emissivity, which is used to absorb and stabilize the heating power fluctuations of the electric heating unit and maintain stable radiant energy.

[0016] The electric heating unit is embedded inside the heat storage unit and is arranged in a spiral shape to ensure that the heat storage unit is heated evenly; the conductive unit is connected to the electric heating unit and extends to the outside of the furnace body to supply power to the electric heating unit.

[0017] The high heat capacity of the heat storage unit acts as a low-pass filter, which can filter out the high-frequency heating power disturbance caused by the intermittent "on-off" control mode of the electric heating unit, and provide a stable thermodynamic environment for the fine structure control of carbon nanotubes.

[0018] The gas inlet unit and the gas outlet unit are respectively connected to both ends of the furnace tube unit, and are used to deliver carbon source gas and protective gas to the area where carbon nanotubes grow and to discharge reaction tail gas; the furnace plug unit is disposed at both ends of the furnace tube unit; the sealing unit includes a sealing flange and a high-temperature resistant sealing ring, which are used to ensure the sealing of the gas passage of the furnace tube unit and prevent oxygen from entering from the external environment.

[0019] The furnace tube unit is arranged along the axial direction of the furnace chamber. The sample carrier unit includes at least a ceramic boat, which is placed inside the furnace tube unit to carry the catalyst for carbon nanotube growth. The support unit is used to fix the furnace tube unit to the focal point O of the energy-concentrating cavity module.

[0020] The support unit is designed with a multi-point support structure to ensure that the furnace tube unit does not deviate from the focal point O when the support unit and the furnace tube unit are heated and expanded at high temperature.

[0021] The insulation module is filled between the outer shell module and the furnace chamber to reduce energy loss and maintain the temperature stability of the furnace tube unit.

[0022] The temperature sensing module's measuring end is in close contact with the outer wall of the furnace tube unit, and is used to detect the temperature of the carbon nanotube growth region.

[0023] The temperature sensing module detects the temperature of the furnace tube unit in real time and transmits an electrical signal containing temperature information to the main control module; the main control module adjusts the power of the heating unit according to the electrical signal.

[0024] In this invention, by setting a heat storage unit in the composite heat source module, the high heat capacity of the unit is used to physically buffer the power fluctuations of the heating unit during switching on and off, converting the energy fluctuations generated by intermittent heating into continuous and stable radiant energy output. This effectively shields the interference of the inherent radiant energy fluctuations of the resistance wire heating mode on the growth of carbon nanotubes. Based on the double elliptical composite surface of the energy-concentrating cavity module, the radiant energy emitted by the composite heat source module is precisely focused on the focal point of the furnace tube unit, enabling the growth area to obtain an efficient and uniform temperature field. By setting a temperature sensing module and a main control module, the real-time detected temperature signals are processed and analyzed, which is beneficial to achieving precise control of the carbon nanotube growth process. By setting a power adjustment module, the power output of the electric heating unit is matched with the temperature deviation, further ensuring the temperature stability of the growth area. Through the synergistic effect of heat storage and focusing, this invention can precisely maintain the stable high-temperature environment required for carbon nanotube growth, which is beneficial to improving the uniformity of carbon nanotube diameter, structural integrity, and batch consistency, thereby improving product quality. At the same time, a stable temperature field can extend the service life of the catalyst and improve the conversion rate of carbon source gas, which is of great significance for reducing production costs and promoting the large-scale application of carbon nanotubes. This invention effectively solves the problem in the prior art that the fluctuation of heating power seriously affects the growth stability of carbon nanotubes, making it difficult to control the quality of carbon nanotubes. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1This diagram illustrates the connection relationships of the regenerative focusing fixed-bed reactor for carbon nanotube preparation provided in this embodiment of the invention. Figure 2 This is a schematic diagram of the furnace design in the regenerative focusing fixed-bed reactor for carbon nanotube preparation provided in an embodiment of the present invention; Figure 3 This diagram illustrates the overall design of a regenerative focusing fixed-bed reactor for carbon nanotube fabrication provided in an embodiment of the present invention. Figure 4 This diagram illustrates the design of the energy-concentrating cavity module in a regenerative focusing fixed-bed reactor for carbon nanotube preparation, as provided in an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 10. Furnace body; 20. Furnace chamber; 30. Control center; 11. Outer shell module; 12. Insulation module; 21. Energy-concentrating cavity module; 22. Composite heat source module; 23. Gas passage module; 24. Material reaction module; 31. Temperature sensing module; 32. Main control module; 33. Power regulation module; 34. Display module; 211. Cavity shell unit; 212. Liner reflection unit; 221. Heat storage unit; 222. Electric heating unit; 223. Conductive unit; 231. Air inlet unit; 232. Air outlet unit; 233. Furnace plug unit; 234. Sealing unit; 241. Furnace tube unit; 242. Sample carrying unit; 243. Support unit; F1, F2, and O are all focal points. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0030] See Figures 1 to 4The present invention provides a regenerative focusing fixed bed reactor for carbon nanotube preparation, which is used to absorb and stabilize the influence of heating power fluctuations on carbon nanotube growth, including a furnace body (10), a furnace chamber (20) and a control center (30); the furnace body (10) is sleeved outside the furnace chamber (20), and the control center (30) is connected to the furnace chamber (20).

[0031] Preferably, the regenerative focusing fixed-bed reactor for carbon nanotube preparation is a laboratory or pilot-scale reactor, with a heating power fluctuation range of 200~5000 W.

[0032] The furnace body (10) includes an outer shell module (11) and a heat preservation module (12); the furnace chamber (20) includes an energy-concentrating cavity module (21), a composite heat source module (22), a gas passage module (23), and a material reaction module (24); the control center (30) includes a temperature sensing module (31), a main control module (32), a power adjustment module (33), and a display module (34); the energy-concentrating cavity module (21) includes a cavity shell unit (211) and an inner lining reflection unit (212); the composite heat source module (22) includes a heat storage unit (221), an electric heating unit (222), and a conductive unit (223); the gas passage module (23) includes an air inlet unit (231), an air outlet unit (232), a furnace plug unit (233), and a sealing unit (234); the material reaction module (24) includes a furnace tube unit (241), a sample carrying unit (242), and a support unit (243).

[0033] The composite heat source module (22) generates energy through the electric heating unit (222), which raises and stabilizes the temperature of the heat storage unit (221); the radiant energy emitted by the heat storage unit (221) is reflected by the inner lining reflector (212) and focused on the furnace tube unit (241); the temperature sensing module (31) detects the temperature of the furnace tube unit (241) in real time and transmits the temperature signal to the main control module (32); the main control module (32) adjusts the power of the electric heating unit (222) through the power adjustment module (33) according to the deviation between the set temperature and the detected temperature.

[0034] The cross-section of the energy-concentrating cavity module (21) is a double-elliptical composite surface that is symmetrical from left to right, including a first ellipse and a second ellipse; the foci of the first ellipse include foci F1 and foci O, the foci of the second ellipse include foci F2 and foci O, and the first ellipse and the second ellipse share the same foci O.

[0035] The composite heat source module (22) is simultaneously located at both focal points F1 and F2, and the material reaction module (24) is located at focal point O.

[0036] Preferably, the first ellipse and the second ellipse have the same eccentricity to ensure the symmetry of the radiation energy transfer path; the eccentricity is set between 0.6 and 0.8.

[0037] Preferably, the energy-concentrating cavity module (21) focuses radiant energy, thereby increasing the heat utilization rate by more than 30%.

[0038] The inner lining reflective unit (212) is a high infrared reflective coating applied to the inner wall of the cavity shell unit (211) to focus the radiant energy of the heat storage unit (221) onto the furnace tube unit (241).

[0039] Preferably, the temperature of the furnace tube unit (241) is 600~1000 ℃, which is capable of growing carbon nanotubes.

[0040] Preferably, the furnace tube unit (241) is made of high-purity quartz glass, which has excellent light transmittance in the infrared band (transmittance ≥90%), ensuring that the infrared radiation emitted by the heat storage unit (221) can efficiently penetrate the furnace tube wall and directly act on the catalyst and carbon source gas inside the furnace tube unit (241), reducing energy loss during the energy transfer process.

[0041] Preferably, the coating material includes a metal reflective layer and / or a dielectric reflective layer; the metal reflective layer is selected from at least one of gold, silver, aluminum, and copper; the dielectric reflective layer is composed of alternating layers of high-refractive-index materials and low-refractive-index materials, wherein the high-refractive-index material is selected from at least one of hafnium dioxide, titanium dioxide, zirconium dioxide, and zinc sulfide, and the low-refractive-index material is selected from at least one of silicon dioxide and magnesium fluoride.

[0042] The heat storage unit (221) is made of a material with high heat capacity and high infrared emissivity, which is used to absorb and stabilize the heating power fluctuations of the electric heating unit (222) and maintain stable radiation energy.

[0043] Preferably, the material of the heat storage unit (221) includes, but is not limited to, silicon carbide, mullite, high-alumina materials, cordierite, corundum, and rare earth silicate ceramics or composite materials with high infrared emissivity.

[0044] The electric heating unit (222) is embedded inside the heat storage unit (221), and the electric heating unit (222) is arranged in a spiral shape to ensure that the heat storage unit (221) is heated evenly.

[0045] The conductive unit (223) is connected to the heating unit (222) and extends to the outside of the furnace body (10) to supply power to the heating unit (222).

[0046] Preferably, the electric heating unit (222) is spirally distributed, including at least one of single spiral and double spiral structures, the bending path includes at least S-shape, the pitch is 10~50 mm, and the spiral diameter is 0.6~0.9 times the width of the heat storage unit (221).

[0047] Preferably, the heating unit (222) is made of resistance wire with a power density of 5~15 W / cm2.

[0048] Preferably, the electric heating unit (222) and the heat storage unit (221) can be filled with a thermally conductive medium or be tightly bonded to reduce contact thermal resistance.

[0049] Preferably, through the heat buffering effect of the heat storage unit (221), the temperature fluctuation of the furnace tube unit (241) can be controlled within ±1 ℃.

[0050] The inlet unit (231) and outlet unit (232) are respectively connected to both ends of the furnace tube unit (241) to deliver carbon source gas and protective gas to the carbon nanotube growth area and discharge reaction tail gas.

[0051] The furnace plug unit (233) is disposed at both ends of the furnace tube unit (241).

[0052] The sealing unit (234) includes a sealing flange and a high-temperature resistant sealing ring, which are used to ensure the sealing of the gas passage of the furnace tube unit (241) and prevent oxygen from entering from the external environment.

[0053] Preferably, the carbon source gas includes at least one of methane, ethylene, and propylene; the protective gas includes at least one of nitrogen and argon; the gas supplied by the intake unit also includes a reducing gas, which includes at least hydrogen, for activating the catalyst before supplying the carbon source gas.

[0054] It should be noted that the furnace plug unit (233) is located at both ends of the furnace tube unit (241) and is made of high-temperature resistant heat-insulating materials such as porous ceramics or quartz fiber. It is used to thermally isolate the internal area of ​​the furnace tube unit (241) from the external environment, reduce the heat loss at the end of the furnace tube unit (241), and maintain the temperature stability of the reaction area. The porous structure of the furnace plug unit (233) allows the gas to pass through evenly, which plays a role in stabilizing the airflow and avoiding turbulence. It ensures that the carbon source gas and the protective gas flow smoothly over the catalyst surface, which is conducive to the uniform and stable growth of carbon nanotubes.

[0055] The furnace tube unit (241) is arranged along the axial direction of the furnace chamber (20), and the sample carrier unit (242) includes at least a ceramic boat placed inside the furnace tube unit (241) to carry the catalyst for carbon nanotube growth.

[0056] The support unit (243) is used to fix the furnace tube unit (241) at the focal point O of the energy-concentrating cavity module (21).

[0057] Preferably, the catalyst carried by the sample carrier unit (242) is a supported transition metal catalyst, including at least one of iron, cobalt, and nickel, and is supported on an alumina, magnesium oxide, or molecular sieve support, for catalyzing the cracking of carbon source gas to generate carbon nanotubes.

[0058] The heat preservation module (12) is filled between the outer shell module (11) and the furnace chamber (20) to reduce energy loss and maintain the temperature stability of the furnace tube unit (241).

[0059] The temperature sensing module (31) has its measuring end in close contact with the outer wall of the furnace tube unit (241) to detect the temperature of the carbon nanotube growth area.

[0060] Preferably, at least four temperature measuring ends are used, evenly distributed on the outer wall of the furnace tube unit (241); the temperature measuring ends are thermocouples, including at least one type K thermocouple or one type S thermocouple.

[0061] It should be noted that the display module (34) is electrically connected to the main control module (32) and is used to display operating parameters such as current temperature, set temperature, and heating power in real time, so as to facilitate monitoring by operators.

[0062] It should be noted that the main control module (32) has preset temperature control curves for different growth stages of carbon nanotubes, including at least a heating stage, an activation stage, a growth stage, and a cooling stage; the heating stage is used to raise the temperature to the growth temperature of carbon nanotubes; the activation stage is used to activate the activity of the catalyst; the growth stage is used for the growth of carbon nanotubes; and the cooling stage is no longer heated and is cooled to the ambient temperature.

[0063] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0064] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0065] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A regenerative focusing fixed-bed reactor for carbon nanotube preparation, characterized in that, The furnace body (10), furnace chamber (20), and control center (30) are used to absorb and stabilize the influence of heating power fluctuations on carbon nanotube growth. The furnace body (10) is fitted outside the furnace chamber (20), and the control center (30) is connected to the furnace chamber (20). The furnace body (10) includes an outer shell module (11) and a heat preservation module (12); the furnace chamber (20) includes an energy-concentrating cavity module (21), a composite heat source module (22), a gas passage module (23), and a material reaction module (24); the control center (30) includes a temperature sensing module (31), a main control module (32), a power adjustment module (33), and a display module (34); the energy-concentrating cavity module (21) includes a cavity shell unit (211) and an inner lining reflection unit (212); the composite heat source module (22) includes a heat storage unit (221), an electric heating unit (222), and a conductive unit (223); the gas passage module (23) includes an air inlet unit (231), an air outlet unit (232), a furnace plug unit (233), and a sealing unit (234); the material reaction module (24) includes a furnace tube unit (241), a sample carrying unit (242), and a support unit (243). The composite heat source module (22) generates energy through the electric heating unit (222), which raises and stabilizes the temperature of the heat storage unit (221); the radiant energy emitted by the heat storage unit (221) is reflected by the inner lining reflector (212) and focused on the furnace tube unit (241); the temperature sensing module (31) detects the temperature of the furnace tube unit (241) in real time and transmits the temperature signal to the main control module (32); the main control module (32) adjusts the power of the electric heating unit (222) through the power adjustment module (33) according to the deviation between the set temperature and the detected temperature.

2. The regenerative focusing fixed-bed reactor for carbon nanotube preparation according to claim 1, characterized in that, The cross-section of the energy-concentrating cavity module (21) is a double-elliptical composite surface with left and right symmetry, including a first ellipse and a second ellipse; the foci of the first ellipse include foci F1 and foci O, the foci of the second ellipse include foci F2 and foci O, and the first ellipse and the second ellipse share the same foci O; the composite heat source module (22) is simultaneously located at foci F1 and foci F2, and the material reaction module (24) is located at foci O.

3. The regenerative focusing fixed-bed reactor for carbon nanotube preparation according to claim 1, characterized in that, The inner lining reflective unit (212) is a high infrared reflective coating applied to the inner wall of the cavity shell unit (211) to focus the radiant energy of the heat storage unit (221) onto the furnace tube unit (241).

4. The regenerative focusing fixed-bed reactor for carbon nanotube preparation according to claim 1, characterized in that, The heat storage unit (221) is made of a material with high heat capacity and high infrared emissivity, which is used to absorb and stabilize the heating power fluctuations of the electric heating unit (222) and maintain stable radiation energy.

5. The regenerative focusing fixed-bed reactor for carbon nanotube preparation according to claim 1, characterized in that, The electric heating unit (222) is embedded inside the heat storage unit (221), and the electric heating unit (222) is arranged in a spiral shape to make the heat storage unit (221) heat evenly; the conductive unit (223) is connected to the electric heating unit (222) and extends to the outside of the furnace body (10) to supply power to the electric heating unit (222).

6. The regenerative focusing fixed-bed reactor for carbon nanotube preparation according to claim 1, characterized in that, The inlet unit (231) and the outlet unit (232) are respectively connected to both ends of the furnace tube unit (241) to deliver carbon source gas and protective gas to the carbon nanotube growth area and discharge reaction tail gas; the furnace plug unit (233) is disposed at both ends of the furnace tube unit (241); the sealing unit (234) includes a sealing flange and a high temperature resistant sealing ring to ensure the sealing of the gas passage of the furnace tube unit (241) and prevent oxygen from entering from the external environment.

7. The regenerative focusing fixed-bed reactor for carbon nanotube preparation according to claim 1, characterized in that, The furnace tube unit (241) is arranged along the axial direction of the furnace chamber (20). The sample carrier unit (242) includes at least a ceramic boat, which is placed inside the furnace tube unit (241) to carry the catalyst for carbon nanotube growth. The support unit (243) is used to fix the furnace tube unit (241) to the focal point O of the energy-concentrating cavity module (21).

8. The regenerative focusing fixed-bed reactor for carbon nanotube preparation according to claim 1, characterized in that, The heat preservation module (12) is filled between the outer shell module (11) and the furnace chamber (20) to reduce energy loss and maintain the temperature stability of the furnace tube unit (241).

9. The regenerative focusing fixed-bed reactor for carbon nanotube preparation according to claim 1, characterized in that, The temperature sensing module (31) has its measuring end in close contact with the outer wall of the furnace tube unit (241) to detect the temperature of the carbon nanotube growth area.

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