A staggered double-channel atomization feeding device for preparing carbon nanotube fibers by floating catalyst chemical vapor deposition method

Abstract

A staggered dual-channel atomizing feed device for preparing carbon nanotube fibers using a float-catalyst chemical vapor deposition method includes a central guide pipe, a feed pipe for the reactor, a flange structure, and a temperature testing pipe. The outer circumference of the temperature testing pipe is equally spaced at 120° intervals around its axis, with a first liquid injection pipe, a second liquid injection pipe, and a carrier gas delivery pipe. The inner ports of the first and second liquid injection pipes are respectively equipped with conical atomizing nozzles, and the two conical atomizing nozzles are staggered along the axial direction of the central guide pipe. This invention enables continuous and uniform replenishment of liquid-phase catalyst and liquid-phase carbon source, improving carbon source conversion rate and effectively solving problems such as fiber breakage, poor continuity, low yield and purity during carbon nanotube fiber preparation. The device has a stable and reliable structure and is suitable for continuous industrial production of carbon nanotube fibers.

Description

Technical Field

[0001] This invention belongs to the field of carbon nanotube fiber preparation technology, specifically relating to a staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by floating catalyst chemical vapor deposition. Background Technology

[0002] The information disclosed in this background section is intended only to enhance some understanding of the overall background of this disclosure and is not necessarily to be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art.

[0003] Carbon nanotube fibers, as a one-dimensional carbon-based composite material with high strength, high modulus, high thermal conductivity, and good flexibility, have broad application prospects in aerospace, electronics, new energy, and biomedicine. Currently, the main methods for preparing carbon nanotube fibers include wet spinning, vapor phase growth, and chemical vapor deposition with a floating catalyst. Among these, chemical vapor deposition with a floating catalyst has become one of the mainstream technologies for large-scale industrial production due to its advantages such as continuous preparation, high fiber purity, and uniform structure.

[0004] However, existing flotation catalyst chemical vapor deposition methods still face many technical bottlenecks in practical applications: First, carbon source materials are usually injected into the pyrolysis chamber through a single-diameter inlet, which easily leads to problems such as discontinuous material supply and uneven local concentration distribution, resulting in interruption and breakage of carbon nanotube fiber growth and poor continuity; Second, the pyrolysis efficiency of carbon source with a single-diameter inlet is low, causing material waste and limiting the increase in fiber production yield; Third, the poor matching degree between material supply and pyrolysis reaction makes it impossible to replenish carbon source in real time according to the pyrolysis process, further exacerbating the problems of low yield, poor purity, and unstable fiber performance.

[0005] To address the aforementioned issues, there is an urgent need to develop an imported device capable of continuous and precise replenishment of carbon sources. This would solve the problems of poor continuity, easy breakage, low yield, and low carbon source conversion rate in the preparation of carbon nanotube fibers using the flotation catalyst chemical vapor deposition method, thereby promoting the industrial production of carbon nanotube fibers. Summary of the Invention

[0006] This invention discloses a staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition, aiming to solve the problems of poor continuity, low purity, low yield and low carbon source conversion rate in the preparation of carbon nanotube fibers by flotation catalyst chemical vapor deposition as mentioned in the background art.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition includes a central guide pipe, a reactor feed pipe, and two liquid injection lines. One end of the central guide pipe is connected to the reactor feed pipe port via a flange structure, and the other end of the central guide pipe is closed, with a temperature testing pipe running through it along the axis of the closed end. The temperature testing pipe has a probe for a temperature sensor to pass through, and the probe is used to detect the temperature inside the reactor feed pipe cavity. The outer circumference of the temperature testing pipe has secondary atomizing lines evenly spaced at 120° intervals around its axis. The reactor includes a first liquid injection pipeline, a second liquid injection pipeline, and a carrier gas delivery pipeline. The inner ports of the first liquid injection pipeline, the second liquid injection pipeline, and the carrier gas delivery pipeline extend into the inner cavity of the feed pipe of the reactor along a direction parallel to the axis of the central guide pipe. The first liquid injection pipeline and the second liquid injection pipeline are used to transport a mixed solution of liquid carbon source and liquid catalyst precursor. The carrier gas delivery pipeline is used to transport one or more of the following mixed gases: argon, nitrogen, and hydrogen. The inner ports of the first liquid injection pipeline and the second liquid injection pipeline are respectively equipped with conical atomizing nozzles. The two conical atomizing nozzles are staggered along the axial direction of the central guide pipe.

[0008] Preferably, the axes of the first liquid injection pipeline, the second liquid injection pipeline, and the carrier gas delivery pipeline are at the same distance from the axis of the temperature testing pipeline.

[0009] Preferably, the inner ports of the first injection pipeline and the second injection pipeline are respectively equipped with a first connecting pipe and a second connecting pipe, and the first connecting pipe and the second connecting pipe are respectively equipped with swirl flow stabilizers.

[0010] Preferably, the conical atomizing nozzle of the first injection pipeline is the first atomizing nozzle, and the conical atomizing nozzle of the second injection pipeline is the second atomizing nozzle. The first atomizing nozzle is located on the side of the second atomizing nozzle facing the closed end, and the distance between the two is 30~150 mm.

[0011] Preferably, the inner ports of the carrier gas delivery pipeline and the temperature test pipeline are both located on the side of the second connector away from the closed end.

[0012] Preferably, the number of blades in the swirl stabilizer is 1 to 5.

[0013] Preferably, the ratio of the inner diameter of the nozzle of the first atomizing nozzle and the inner diameter of the first liquid injection pipe and the second liquid injection pipe is 1:2~3.

[0014] Preferably, the inner cavity of the central guide pipe and the inner cavity of the feed pipe of the reactor are respectively sealed and fixedly connected with a first support plate and a second support plate. The first support plate is provided with guide holes for the first liquid injection pipe, the second liquid injection pipe, the carrier gas delivery pipe, and the temperature test pipe to pass through. The second support plate is provided with through holes for the first connecting pipe, the second connecting pipe, the carrier gas delivery pipe, and the temperature test pipe to pass through. The first connecting pipe, the second connecting pipe, the carrier gas delivery pipe, and the temperature test pipe are respectively sealed and fixedly connected to the through holes.

[0015] The beneficial effects of the staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition of the present invention are as follows: This invention enables continuous and uniform replenishment of liquid-phase catalysts and liquid-phase carbon sources, improves carbon source conversion rate, and effectively solves problems such as easy fiber breakage, poor continuity, low yield and purity in the preparation of carbon nanotube fibers. The structure is stable and reliable, and it is suitable for continuous industrial production of carbon nanotube fibers. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by floating catalyst chemical vapor deposition according to the present invention. Figure 2 This is an axial view of the front end of the liquid injection port of a staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition according to the present invention. Figure 3 This is a cross-sectional view along the first and second liquid injection lines of a staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by floating catalyst chemical vapor deposition according to the present invention. Figure 4 This is a cross-sectional view along the first liquid injection pipe and the temperature test pipe of the present invention for a staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by floating catalyst chemical vapor deposition (B in the figure is an enlarged view of point A). Reference numerals in the attached drawings: 1-First injection pipeline; 2-Second injection pipeline; 3-Temperature test pipeline; 4-Carrier gas delivery pipeline; 5-Central guide pipe; 6-Flange plate; 7-First atomizing nozzle; 8-Second atomizing nozzle; 9-Swirl stabilizer; 10-Feed pipe of the reactor; 11-Closed end; 12-First support plate; 13-Second support plate; 14-Second connecting pipe; Figure 5 This invention provides a comparison of the graphitization degree and resistivity of carbon nanotube fibers prepared by a staggered dual-channel atomization feeding device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition, with the graphitization degree and resistivity of carbon nanotube fibers prepared by single-channel liquid injection under the same preparation conditions. Figure 6This invention provides a comparison of the yield and carbon conversion rate of carbon nanotube fibers prepared by a staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition with the yield and carbon conversion rate of carbon nanotube fibers prepared by single-channel liquid injection under the same preparation conditions. Figure 7 This invention provides a comparison of the catalyst residue in carbon nanotube fibers prepared by a staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition with the catalyst residue in carbon nanotube fibers prepared by single-channel liquid injection under the same preparation conditions. Figure 8 This is a schematic diagram illustrating the working principle of the present invention; reference numerals: 01-single injection pipeline; 02-the staggered dual-channel injection pipeline of the present invention; 03-raw material; 04-direction of raw material movement. Detailed Implementation

[0017] The following description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0018] The following embodiments can be understood as illustrating a part of the structure or method of the present invention individually, or as combining the embodiments to explain the broader structure or method of the present invention.

[0019] Example 1: A staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition, such as Figure 1-4 As shown, the reactor includes a central guide pipe 5 and a feed pipe 10. One end of the central guide pipe 5 is connected to the feed pipe 10 of the reactor via a flange structure. The flange structure is a common mechanical structure, such as... Figure 1 As shown, it includes two flange plates 6, which are fixed together by a bolt and nut assembly. A sealing gasket is also provided between the two flange plates 6 to achieve a sealing effect. The feed pipe 10 of the reactor is the inlet end of the reactor body. The carbon source and carrier gas come out from the first liquid injection pipe 1, the second liquid injection pipe 2, and the carrier gas delivery pipe 4 in this area, and the reaction begins. This is the beginning of the entire flotation catalyst chemical vapor deposition reaction.

[0020] like Figure 1-4As shown, the other end of the central guide pipe 5 is closed, and a temperature testing pipe 3 runs through it along the axis of the closed end 11. The temperature testing pipe 3 is used to allow the probe of a temperature sensor (a common structure, not shown in the figure) to pass through. The probe is used to detect the temperature inside the feed pipe of the reactor. Around the outer periphery of the temperature testing pipe 3, at 120° intervals, are distributed a first liquid injection pipe 1, a second liquid injection pipe 2, and a carrier gas delivery pipe 4. The inner ports of the feed pipe 4 extend parallel to the axis of the central guide pipe to the inner cavity of the feed pipe 10 of the reactor. Both the first injection pipe 1 and the second injection pipe 2 are used to transport a mixed solution of liquid carbon source and liquid catalyst precursor. The carrier gas supply pipe 4 is used to transport one or more of the following mixed gases (as carrier gas and protective gas): argon, nitrogen, and hydrogen. The inner ports of the first injection pipe 1 and the second injection pipe 2 are respectively equipped with conical atomizing nozzles, and the two conical atomizing nozzles are staggered along the axial direction of the central guide pipe 5. This embodiment provides a case where there are two injection pipes.

[0021] Example 2: Furthermore, such as Figure 2 As shown, the axes of the first injection pipeline 1, the second injection pipeline 2, and the carrier gas delivery pipeline 4 are all at the same distance from the axis of the temperature testing pipeline 3. The axes of the first injection pipeline 1, the second injection pipeline 2, and the carrier gas delivery pipeline 4 can be connected to form an equilateral triangle perpendicular to the axis of the central guide pipe 5, ensuring the stable delivery of the mixed solution of carrier gas, liquid catalyst, and liquid carbon source.

[0022] Furthermore, such as Figure 3 As shown, the inner ports of the first injection line 1 and the second injection line 2 are respectively equipped with a first connecting pipe (not marked in the figure) and a second connecting pipe 14. A swirl stabilizer 9 is installed inside the first connecting pipe and the second connecting pipe 14. The swirl stabilizer can adopt existing technology structures, such as the swirl stabilizer of a fuel injector. The appendix of this invention... Figure 4 Point B shows a schematic diagram of the swirl stabilizer 9, which has multiple spirally arranged blades with a fixed plate rotatably connected in the middle. The fixed plate is fixedly connected to the inner wall of the first or second connecting pipe via a connecting rod. When the first or second atomizing nozzle sprays high-pressure atomized gas, the atomized gas impacts the blades and causes them to rotate. During this process, the atomized gas is further impacted into finer atomized particles, achieving high-pressure and fine atomization, thereby improving the liquid phase precursor pyrolysis efficiency and carbon source utilization.

[0023] Furthermore, such as Figure 3As shown, the conical atomizing nozzle of the first injection pipeline 1 is the first atomizing nozzle 7, and the conical atomizing nozzle of the second injection pipeline 2 is the second atomizing nozzle 8. The first atomizing nozzle 7 is located on the side of the second atomizing nozzle 8 facing the closed end 11, and the distance between the two is 30~150 mm. This staggered structure can realize segmented continuous feeding along the airflow direction, so that the carbon source concentration in the pyrolysis zone is always maintained in a stable range, avoiding fiber breakage and growth interruption caused by local material shortage, and ensuring timely replenishment of raw materials in the mixed solution of liquid carbon source and liquid catalyst precursor.

[0024] Example 3: like Figure 1 As shown, the inner ports of the carrier gas delivery pipeline 4 and the temperature test pipeline 3 are both located on the side of the second connector 14 away from the closed end 11.

[0025] like Figure 3 As shown, the number of blades of the swirl stabilizer 9 is 1 to 5, which are used to form a weak swirling flow field, improve the uniformity of the distribution of liquid phase precursor on the cross section of the reaction tube, and avoid local concentrations that are too high or too low.

[0026] like Figure 1-4 As shown, the ratio of the inner diameter of the nozzle of the first atomizing nozzle 7 and the second atomizing nozzle 8 to the inner diameter of the first liquid injection line 1 and the second liquid injection line 2 is 1:2~3.

[0027] like Figure 3 As shown, the inner cavity of the central guide pipe 5 and the inner cavity of the feed pipe 10 of the reactor are respectively sealed and fixedly connected to a first support plate 12 and a second support plate 13. The first support plate 12 is provided with guide holes for the first liquid injection pipe 1, the second liquid injection pipe 2, the carrier gas delivery pipe 4, and the temperature testing pipe 3 to pass through. The second support plate 13 is provided with through holes for the first connecting pipe 14, the second connecting pipe 14, the carrier gas delivery pipe 4, and the temperature testing pipe 3 to pass through. The first connecting pipe 14, the second connecting pipe 14, the carrier gas delivery pipe 4, and the temperature testing pipe 3 are respectively sealed and fixedly connected to the through holes. The fixation of each pipe is achieved by setting the first support plate, the second support plate, and the closed end together.

[0028] Working principle of the invention: The device is installed at the front end of the feed pipe 10 of the reactor via flange plate 6; a mixed solution of liquid carbon source and liquid catalyst precursor is simultaneously pumped in through the first liquid injection pipe 1 and the second liquid injection pipe 2; carrier gas is continuously introduced through carrier gas delivery pipe 4; the two liquids are atomized by the first atomizing nozzle 7 and the second atomizing nozzle 8 and sprayed out after being stabilized by the swirl flow stabilizer plate 9; due to the axial misalignment of the two nozzles, continuous feeding and gradient supply along the airflow direction are achieved; the temperature sensor extends into the cavity of the feed pipe 10 of the reactor through the temperature testing pipe 3 to monitor the temperature of the pyrolysis zone in real time; the atomized droplets enter the high-temperature pyrolysis zone of the reactor under the carrying of the carrier gas, where the carbon source is fully catalyzed and pyrolyzed, and assembled and grown into carbon nanotube fibers under the traction of continuous airflow, realizing continuous, stable, high-purity and high-yield preparation.

[0029] The principle behind the "misaligned structure mentioned in this invention enables segmented continuous feeding along the airflow direction, maintaining the carbon source concentration in the pyrolysis zone within a stable range, avoiding fiber breakage and growth interruption due to localized material shortages, and ensuring timely replenishment of the liquid carbon source and liquid catalyst precursor mixed solution" is as follows: Figure 8 As shown, during the rapid flow of carrier gas into the reactor along the feed pipe, a negative pressure is generated around the carrier gas, which in turn exerts a pulling force on the raw material transported by the liquid injection pipeline, causing the originally continuously transported atomized gas to be broken, resulting in uneven distribution. Traditional methods using a single liquid injection pipeline cannot effectively solve the problem of uneven dispersion of the raw material due to the negative pressure. This invention designs a first liquid injection pipeline and a second liquid injection pipeline that are staggered in the feeding direction and have an angular difference in the radial direction within the inner cavity of the reactor's feed pipe, as shown... Figure 8 As shown, although the raw materials output from the two injection lines may also be broken by negative pressure, the broken materials complement each other, filling the gaps at the break points. This ensures uniform material distribution and prevents fiber breakage and growth interruption caused by localized material shortages. The principle of this complementarity at the break points is as follows: the raw materials output from the first or second injection line have a certain degree of swirling flow. When adjacent raw materials are broken, the swirling material can quickly fill the gaps due to centrifugal force and the decrease in air pressure at the break point, maintaining a continuous and uniform material delivery. The slightly offset design at certain angles makes this gap-filling effect even easier to achieve.

[0030] Experimental verification: As attached Figure 5 Appendix Figure 6 Appendix Figure 7 As shown, carbon nanotube fibers prepared using a staggered dual-channel atomization feeding device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition show improvements compared to traditional single-channel feeding: 1) Higher degree of graphitization, lower resistivity, and more complete fiber structure; 2) Production and carbon source conversion rate have been significantly improved, and raw material waste has been reduced; 3) Lower catalyst residue, higher fiber purity, and more stable continuity and mechanical properties.

[0031] As can be seen, the remarkable effects of the present invention as designed above have been fully verified by experimental data.

[0032] Understandably, as needed, two or more injection pipelines can be arranged in a staggered sequence, with a set spacing between each pipeline along the axial direction of the reactor's feed pipe and an angular offset along the radial direction of the reactor's feed pipe. The principle for improving the raw material supply effect is the same as above.

[0033] The above embodiments are preferred embodiments of this disclosure, but the embodiments of this disclosure are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of this disclosure shall be considered equivalent substitutions and shall be included within the protection scope of this disclosure.

Claims

1. A staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition, characterized in that, The system includes a central guide pipe, a reactor feed pipe, and two liquid injection lines. One end of the central guide pipe is connected to the reactor feed pipe port via a flange. The other end of the central guide pipe is closed, and a temperature testing pipe runs through it along the axis of the closed end. The temperature testing pipe allows a temperature sensor probe to pass through, which detects the temperature inside the reactor feed pipe. Around the outer circumference of the temperature testing pipe, a first liquid injection line, a second liquid injection line, and a carrier gas delivery line are distributed at 120° intervals along the axis. The inner ports of the first liquid injection pipeline, the second liquid injection pipeline, and the carrier gas delivery pipeline extend to the inner cavity of the feed pipe of the reactor along a direction parallel to the axis of the central guide pipe. The first liquid injection pipeline and the second liquid injection pipeline are used to transport a mixed solution of liquid carbon source and liquid catalyst precursor. The carrier gas delivery pipeline is used to transport one or more of the following mixed gases: argon, nitrogen, and hydrogen. The inner ports of the first liquid injection pipeline and the second liquid injection pipeline are respectively provided with conical atomizing nozzles. The two conical atomizing nozzles are staggered along the axial direction of the central guide pipe.

2. The staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition as described in claim 1, characterized in that, The axes of the first injection pipeline, the second injection pipeline, and the carrier gas delivery pipeline are all at the same distance from the axis of the temperature testing pipeline.

3. The staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition as described in claim 2, characterized in that, The inner ports of the first and second injection lines are respectively equipped with a first connector and a second connector, and the first and second connectors are respectively equipped with swirl flow stabilizers.

4. The staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition as described in claim 3, characterized in that, The conical atomizing nozzle of the first injection pipeline is the first atomizing nozzle, and the conical atomizing nozzle of the second injection pipeline is the second atomizing nozzle. The first atomizing nozzle is located on the side of the second atomizing nozzle facing the closed end, and the distance between the two is 30~150 mm.

5. The staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition as described in claim 4, characterized in that, The inner ports of the carrier gas delivery pipeline and the temperature test pipeline are both located on the side of the second connector away from the closed end.

6. The staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition as described in claim 5, characterized in that, The swirl stabilizer has 1 to 5 blades.

7. The staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition as described in claim 6, characterized in that, The ratio of the inner diameter of the first atomizing nozzle and the second atomizing nozzle to the inner diameter of the first liquid injection pipe and the second liquid injection pipe is 1:2~3.

8. The staggered dual-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition as described in claim 7, characterized in that, The inner cavity of the central guide pipe and the inner cavity of the feed pipe of the reactor are respectively sealed and fixedly connected with a first support plate and a second support plate. The first support plate is provided with guide holes for the first liquid injection pipe, the second liquid injection pipe, the carrier gas delivery pipe, and the temperature test pipe to pass through. The second support plate is provided with through holes for the first connecting pipe, the second connecting pipe, the carrier gas delivery pipe, and the temperature test pipe to pass through. The first connecting pipe, the second connecting pipe, the carrier gas delivery pipe, and the temperature test pipe are respectively sealed and fixedly connected to the through holes.

9. A staggered multi-channel atomizing feed device for preparing carbon nanotube fibers by flotation catalyst chemical vapor deposition, characterized in that, The difference between the multi-channel atomizing feed device and the staggered dual-channel atomizing feed device as described in any one of claims 1-8 is that: there are two or more liquid injection pipelines, and the inner ends of each pipeline have a set spacing along the axial direction of the feed pipe of the reactor, and the adjacent pipelines are angularly staggered in the radial direction of the feed pipe of the reactor.

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