Material receiving device and material receiving method for preparing carbon nanotubes

Abstract

The invention relates to a material receiving device and a material receiving method for preparing a carbon nano tube, and belongs to the technical field of carbon nano tube aggregate preparation and high-temperature chemical process equipment. The invention provides a material receiving device for preparing a carbon nano tube. The material receiving device mainly comprises a bin body, and a clean gas chamber, a dirty gas chamber and other structures which are arranged in the bin body. The invention aims to overcome the defects in the prior art and provides an integrated material receiving device special for preparing the carbon nanotube aggregate under the conditions of high temperature and high flow. According to the invention, a low-efficiency multi-stage series connection mode with potential safety hazards is abandoned, cooling, filtering, unloading and safety monitoring functions are integrated in a single pressure container through a highly integrated design, and continuous, safe and efficient material receiving under the protection of a fully-closed inert atmosphere in the whole process is realized.

Description

Technical Field

[0001] This invention relates to a material collection device and method for preparing carbon nanotubes, belonging to the technical field of carbon nanotube aggregate preparation and high-temperature chemical process equipment. Background Technology Currently, most carbon nanotube fabrication processes generate high temperatures (typically exceeding 1000°C), utilizing hydrocarbons, hydrogen, catalysts, and argon to prepare carbon nanotubes. Due to their high energy consumption and vigorous reactions, these processes place extremely stringent requirements on the subsequent product collection system, and traditional powder collection methods have significant shortcomings. 1) Unique product properties: The generated carbon nanotubes are lightweight, one-dimensional fibrous, easily aggregate, and have a very large surface area. Traditional mechanical separation equipment (such as cyclone separators) has low separation efficiency, and high-speed airflow and mechanical collisions can easily cause the brittle carbon nanotubes to break and the structure to be damaged, which seriously affects the product quality.

[0002] 2) Extremely high safety risks: The main components of the reaction tail gas are high-temperature hydrogen and unreacted methane, along with carbon nanoparticles. Hydrogen has an extremely wide explosion limit (4%-75%), and carbon nanoparticles can also form explosive mixtures in air. Carbon nanotubes are flammable upon contact with oxygen at high temperatures; therefore, the entire material collection process must be carried out under an absolutely reliable inert atmosphere.

[0003] 3) Process continuity requirements: Industrial production requires equipment to operate stably and continuously for extended periods. Traditional collection methods are mostly intermittent operations, which cannot meet the demand for continuous output, thus becoming a bottleneck in the production process.

[0004] Currently, common collection schemes often employ a series collection mode of "water quenching + cyclone separation + bag filter". This mode has inherent drawbacks: water quenching can cause carbon nanotubes to agglomerate, increasing subsequent drying costs and process complexity; cyclone separators have low collection efficiency for nanomaterials; and the increased number of connecting pipes between multiple devices not only increases system resistance but also raises the risk of leakage and oxygen infiltration.

[0005] Therefore, there is an urgent need in this field to develop a dedicated material collection device that can fundamentally solve the above problems and achieve efficient collection, intrinsic safety, continuous operation, and guaranteed product quality. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an integrated material collection device specifically designed for the preparation of carbon nanotube aggregates under high temperature and high flow conditions. This invention abandons the inefficient and unsafe multi-stage series mode, and through a highly integrated design, integrates cooling, filtration, unloading, and safety monitoring functions into a single pressure vessel, achieving continuous, safe, and efficient material collection under a fully enclosed inert atmosphere throughout the entire process.

[0007] In a first aspect, the present invention provides a receiving apparatus for preparing carbon nanotubes, comprising: The chamber has a purification gas pipe and a nitrogen main pipeline connected to its top, and a process gas inlet is provided on its side. A clean air chamber is provided in the upper part of the inner cavity of the chamber body, and a jet blowing component is provided in the clean air chamber; The dirty air chamber is located in the lower part of the inner cavity of the chamber body. The dirty air chamber is equipped with a filter element group connected to the blowing assembly, and a cooling coil is provided at the bottom of the filter element group. The clean air chamber and the dirty air chamber are separated by a perforated plate, the air intake assembly can pass through the perforated plate, and the perforated plate is equipped with a differential pressure sensor; The discharge hopper is connected to the bottom of the dirty air chamber.

[0008] Furthermore, an explosion-proof membrane is installed on the top of the silo.

[0009] Furthermore, the injection assembly includes a main injection pipe connected to the main nitrogen pipeline and multiple injection pipe branches located at the end of the main injection pipe.

[0010] Furthermore, each of the blowpipe branch pipes is equipped with a Venturi tube.

[0011] Furthermore, the filter element group includes multiple filter elements arranged parallel to each other along the height direction of the chamber. Each filter element has a hollow channel and multiple air holes that connect to the hollow channel, and the hollow channel connects to the clean air chamber.

[0012] Furthermore, the filter element is a sintered metal filter element.

[0013] Furthermore, the cooling coil has a spiral structure and is laid in the lower space of the filter element group in the dirty air chamber.

[0014] Furthermore, the discharge hopper has a funnel-shaped structure, with a two-stage rotary star-shaped discharge valve at its bottom, and an explosion-proof sight glass is provided on the side of the discharge hopper.

[0015] Furthermore, a cooling jacket is provided on the outside of the chamber.

[0016] Secondly, the present invention provides a material receiving method, which utilizes the aforementioned material receiving device, comprising: The high-temperature process gas used to prepare the carbon nanotube furnace is introduced into the dirty gas chamber through the process gas inlet. The process gas is cooled by the cooling coil. The process gas comes into contact with the filter element group from the outside to the inside and is filtered to obtain purified gas. The purified gas moves sequentially from bottom to top through the filter group into the clean gas chamber, and is then drawn away through the purified gas pipe. The differential pressure sensor on the tube sheet detects the differential pressure value and transmits it to the PLC. The PLC then controls the opening and closing of the purified air pipe and triggers the explosion-proof pulse valve.

[0017] The beneficial effects of this invention are: Extremely high collection efficiency: The final filtration is achieved by using a precision metal sintered filter element, which has a collection efficiency of >99.9% for carbon nanotube agglomerates, far exceeding that of cyclone separators, and avoids structural damage to the product caused by mechanical collision.

[0018] Intrinsically safe: The entire system is designed to be sealed, integrating real-time oxygen content monitoring and automatic inert gas protection interlock, completely eliminating the risk of explosion and oxidation from both hardware and control system levels.

[0019] Continuous automated operation: Based on differential pressure-triggered automatic pulse backflushing and two-stage sealed unloading, a fully automatic continuous cycle of "filtration-cleaning-unloading" is realized, meeting the requirements of industrial continuous production.

[0020] Superior product quality: Dry indirect cooling avoids product contamination, agglomeration, and complex subsequent drying processes caused by water quenching, resulting in carbon nanotube aggregates with higher purity and better dispersibility.

[0021] Compact structure and high reliability: The integrated design reduces connection points such as pipes and flanges, lowers leakage rate and system resistance, and improves the overall reliability and lifespan of the equipment. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure in one embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the filter element in one embodiment of the present invention.

[0024] In the diagram, 1. Purification gas pipe; 2. Explosion-proof membrane; 31. Nitrogen main pipe; 32. Main jet pipe; 33. Branch jet pipe; 4. Clean gas chamber; 5. Venturi tube; 6. Tube plate; 7. Cooling jacket; 8. Filter element; 81. Hollow channel; 82. Air hole; 9. Inspection port; 10. Dirty gas chamber; 11. Process gas inlet; 12. Cooling coil; 13. Explosion-proof sight glass; 14. Two-stage rotary star valve. Detailed Implementation

[0025] 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.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] In this invention, the terms "first" and "second" are used only to distinguish similar components / parts in different positions or with different characteristics, and have no other limiting meaning; "upper" refers to the direction in which each component is away from the ground, and "lower" refers to the direction in which each component is away from the ground.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] In a first aspect, the present invention provides a receiving device for preparing carbon nanotubes, mainly comprising a chamber, and structures such as a clean air chamber and a dirty air chamber disposed within the chamber, specifically: In some embodiments, the top of the chamber is connected to a purification gas pipe 1 and a nitrogen main pipe 31, wherein the purification gas pipe 1 is used to export the filtered clean gas, and the nitrogen main pipe 31 can be supplied with high-pressure nitrogen to cooperate with the spraying assembly to clean the filter element 8; the side of the chamber is provided with a process gas inlet 11 for receiving high-temperature process gas from the carbon nanotube preparation furnace.

[0030] In some embodiments, the clean air chamber 4 is located in the upper part of the inner cavity of the chamber body as a temporary storage space for the filtered clean gas. The clean air chamber 4 is equipped with a blowing assembly to completely shake the carbon nanotube agglomerates to the discharge hopper at the bottom of the chamber, so as to avoid the filter element 8 from being clogged due to excessive carbon nanotube powder.

[0031] In some embodiments, the dirty gas chamber 10 is located in the lower part of the inner cavity of the chamber body, serving as the main space for filtering process gas containing carbon nanotube powder. The dirty gas chamber 10 is equipped with a filter element group connected to the jetting assembly. The filter element group uses its own porous structure to trap carbon nanotube powder in the process gas. A cooling coil 12 is provided at the bottom of the filter element group to cool the high-temperature process gas entering the dirty gas chamber 10, and at the same time reduce the agglomeration of powder caused by temperature changes during the filtration process.

[0032] In some embodiments, the clean air chamber 4 and the dirty air chamber 10 are separated by a perforated plate 6. The perforated plate 6 serves both as structural support and partial obstruction, and also ensures that the gas between the two chambers flows only through the filter element group. Part of the structure of the jet blowing assembly can penetrate the perforated plate 6 to ensure that the jet blowing airflow acts precisely on the filter element 8. The perforated plate 6 is equipped with a differential pressure sensor to detect the pressure difference between the clean air chamber 4 and the dirty air chamber 10 in real time, thereby determining the degree of clogging of the filter element group.

[0033] In some embodiments, the discharge hopper is a conical hopper structure connected to the bottom of the dirty air chamber 10, used to collect the carbon nanotube powder trapped by the filter cartridge group, so as to realize the centralized recovery of the powder.

[0034] In some embodiments, an explosion-proof membrane 2 is provided on the top of the chamber. When the pressure inside the chamber suddenly increases due to an unexpected situation, the explosion-proof membrane 2 can rupture on its own to release the pressure, preventing the chamber from exploding due to overpressure and improving the safety of the device operation.

[0035] In some embodiments, the blowing assembly includes a main blowing pipe 32 connected to the main nitrogen pipeline 31 and multiple blowing pipe branches 33 disposed at the end of the main blowing pipe 32. The main blowing pipe 32 diverts the high-pressure nitrogen from the main nitrogen pipeline 31 to each blowing pipe branch 33. The multi-branch design can achieve uniform blowing of the filter element group, ensuring that each filter element 8 can be effectively cleaned.

[0036] In some embodiments, each of the blowpipe branch pipes 33 is provided with a Venturi tube 5. The throttling effect of the Venturi tube 5 is used to make the high-pressure nitrogen gas form a high-speed airflow when it is sprayed out, and at the same time, it drives the gas in the surrounding clean air chamber 4 into the filter element 8, thereby enhancing the backflushing force and improving the removal effect of powder on the surface of the filter element 8.

[0037] In some embodiments, the filter element group includes multiple filter elements 8 arranged parallel to each other along the height direction of the chamber. Increasing the number of filter elements 8 can increase the filtration area and improve the processing efficiency of the device. Each filter element 8 has a hollow channel 81 and is provided with multiple air holes 82 that connect to the hollow channel 81. Carbon nanotube powder in the process gas is trapped on the outer surface of the filter element 8, while clean gas enters the hollow channel 81 through the air holes 82. The hollow channel 81 connects to the clean gas chamber 4, allowing the clean gas to enter the clean gas chamber 4 smoothly.

[0038] In some embodiments, the filter element 8 is a sintered metal filter element 8, which has the characteristics of high temperature resistance, high strength and wear resistance, can adapt to the high temperature environment of process gas in the carbon nanotube preparation process, and is not easily damaged by powder friction, thus extending its service life.

[0039] In some embodiments, the cooling coil 12 has a spiral structure and is laid in the lower space of the filter element group in the dirty gas chamber 10. The spiral structure can increase the contact area between the coil and the process gas, improve the heat exchange efficiency, and ensure that the high-temperature process gas is reduced to a suitable temperature before reaching the filter element group. At the same time, the coil is laid in the lower part of the filter element group, which allows the process gas to fully contact the coil during the rising process, thereby achieving gradual cooling.

[0040] In some embodiments, the discharge hopper has a funnel-shaped structure, which facilitates the accumulation of carbon nanotube powder at the bottom by gravity. A two-stage rotary star-shaped discharge valve 14 is provided at the bottom. Through the coordinated action of the two-stage valve, the powder can be discharged smoothly while effectively preventing external air from entering the dirty air chamber 10 and maintaining the pressure stability inside the chamber. An explosion-proof sight glass 13 is provided on the side of the discharge hopper, which makes it easy for operators to observe the powder accumulation in the discharge hopper and keep track of the discharge progress in a timely manner.

[0041] In some embodiments, a cooling jacket 7 is provided on the outside of the chamber. By introducing a cooling medium (such as cooling water) into the jacket, the overall temperature of the chamber can be reduced, and the cooling coil 12 can further reduce the gas temperature in the dirty gas chamber 10. At the same time, it can prevent the outer wall of the chamber from overheating due to the high internal temperature, thus ensuring operational safety.

[0042] Secondly, the present invention provides a material receiving method, which utilizes the aforementioned material receiving device, comprising: The high-temperature process gas used to prepare the carbon nanotube furnace is introduced into the dirty gas chamber 10 through the process gas inlet 11. After entering, the high-temperature process gas first comes into contact with the spiral cooling coil 12 at the bottom. Through the cooling medium in the coil, heat exchange occurs between the process gas and the cooling medium, causing the gas temperature to drop from high temperature to a temperature range suitable for filtration by the filter element 8 (usually 100-200℃). This reduces the risk of damage to the filter element 8 and powder agglomeration caused by high temperature. The cooled process gas flows upward under the action of pressure difference, contacting the filter element group from the outside to the inside. The carbon nanotube agglomerates are precisely intercepted on the outer surface of the filter element 8, resulting in purified gas.

[0043] In some embodiments, the purified gas enters the hollow channel 81 through the pores 82 on the filter element 8, and moves upward along the hollow channel 81 into the clean air chamber 4. At this point, it is drawn away by the exhaust fan at the rear end through the outlet of the purified gas pipe 1. The outlet temperature of the purified gas pipe can be stably controlled below 250°C by the cooling system, forming a stable airflow circulation to ensure continuous filtration.

[0044] In some implementations, the differential pressure sensor on the tube sheet 6 monitors the pressure difference between the clean air chamber 4 and the dirty air chamber 10 in real time. When the differential pressure sensor before and after the tube sheet 6 detects a pressure difference of 12 kPa, a signal is transmitted to the PLC. The PLC first closes the shut-off valve at the purified gas outlet, and then sequentially triggers each explosion-proof pulse valve. High-pressure nitrogen (0.6 MPa) is instantaneously released from the external gas tank, passes through the main nitrogen pipeline 31, and is injected into the interior of each filter element 8 via the main blowpipe 32, the branch blowpipe 33, and the venturi tube 5, respectively, completely shaking off the carbon nanotube agglomerates on their outer surface to the bottom cone hopper. After the cleaning is completed, the outlet shut-off valve opens, and the system resumes filtration.

[0045] In some implementations, the carbon nanotube aggregates accumulated in the discharge hopper at the bottom of the silo are discharged through a two-stage rotary star-shaped discharge valve 14. The host computer sets the discharge time interval, and the impellers of the two-stage dischargers operate alternately, always keeping the system isolated from the atmosphere. The entire discharge process can be observed through an explosion-proof sight glass 13.

[0046] For safety, an oxygen analyzer is installed in the clean air chamber 4 to continuously monitor the atmosphere. Once the oxygen concentration exceeds 1% VOL (alarm value), the PLC will immediately issue an audible and visual alarm and open the solenoid valve on the protection pipeline to purge the chamber with nitrogen. If the concentration continues to rise to 2% VOL (interlock value), the PLC will execute an emergency shutdown procedure: closing the process gas inlet valve, initiating emergency nitrogen purging, stopping the induced draft fan, and triggering an alarm. The explosion-proof membrane 2 installed on the top of the chamber provides final safety relief. Any problems with the entire equipment can be addressed through the reserved inspection port 9.

[0047] The device of this invention is particularly suitable for plasma pyrolysis devices with a gas volume of 50-500 Nm³ / h, and the carbon nanotube aggregate collection efficiency is stable at over 99.95%, realizing safe, efficient and continuous industrial production.

[0048] Example 1 The present invention relates to a process with a gas throughput of 50-200 Nm³ / h. The chamber is a vertical pressure vessel with a diameter of 1.2 meters and a height of 3.5 meters, made of 310S stainless steel. Cooling is achieved using a combination of a jacket 7 and cooling coils 12, both circulated with heat transfer oil. High-temperature process gas enters the dirty gas chamber 10 at the bottom of the chamber through the process gas inlet 11. The gas rises within the chamber and comes into contact with the filter element 8. The gas passes through the filter element 8 from the outside in, where carbon nanotube aggregates are precisely intercepted on the outer surface. The purified gas then enters the hollow channel 81 inside the filter element 8 through the pores 82. From there, the gas enters the clean gas chamber 4 and is drawn away by a fan at the rear end via the purified gas pipe 1. The temperature of the purified gas pipe is stably controlled below 250℃ by the cooling system. The filtration system consists of twelve vertically suspended sintered 316L stainless steel filter elements 8 with a filtration accuracy of 5 microns, and is backflushed and cleaned by a nitrogen pulse system with a pressure ≥0.6MPa. The sealed unloading system employs a two-stage rotary star-shaped unloader 14. The control system, centered on a PLC, integrates differential pressure (set value 12kPa) and oxygen content (alarm value 1%) monitoring, achieving fully automated continuous operation of filtration, cleaning, and unloading. It is particularly suitable for pilot-scale or small-scale industrial production lines.

[0049] Example 2 The present invention relates to a process for handling gas volumes of 300-500 Nm³ / h. The chamber, constructed of high-temperature resistant alloy, has a diameter of 2.5 meters and multiple tangential inlets at the top for uniform airflow distribution. The cooling system utilizes a multi-layered, built-in coil with 12 channels of high-pressure softened water for efficient cooling. The filtration system comprises 36 sintered 310S stainless steel filter elements (1-micron precision), with a pulse backflushing design using a zoned control mode to minimize airflow fluctuations. The unloading system employs a pneumatic double-gate flap valve to ensure reliable sealing under high flow rates. The monitoring and safety control system has been upgraded to a DCS system, featuring redundant oxygen content monitoring and rapid interlock response (<1 second), ensuring long-term stable and safe operation of the equipment under high loads.

[0050] Example 3 The present invention relates to a current process for handling gas volumes of 5-20 Nm³ / h. The chamber is a small 316L stainless steel container with a simplified structure, using only a cooling jacket 7 for basic cooling. The filtration system consists of four filter elements 8 (10-micron precision), coupled with a single-pipe pulse backflushing system that supports manual or timed triggering. Discharge is achieved using a miniature two-stage rotary valve. The control system is a simple PLC or microcontroller, equipped with basic differential pressure monitoring and oxygen content alarm functions. This embodiment is compact, low-cost, and flexible in operation, perfectly suited to the needs of laboratory research and development or small-batch pilot production, while ensuring operational safety under a fully inert atmosphere.

[0051] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A material collection device for preparing carbon nanotubes, characterized in that, include: The chamber has a purification gas pipe and a nitrogen main pipeline connected to its top, and a process gas inlet is provided on its side. A clean air chamber is provided in the upper part of the inner cavity of the chamber body, and a jet blowing component is provided in the clean air chamber; The dirty air chamber is located in the lower part of the inner cavity of the chamber body. A filter element group connected to the blowing assembly is installed in the dirty air chamber. A cooling coil is installed at the bottom of the filter element group. The clean air chamber and the dirty air chamber are separated by a perforated plate, the air intake assembly can pass through the perforated plate, and the perforated plate is equipped with a differential pressure sensor; The discharge hopper is connected to the bottom of the dirty air chamber.

2. The receiving device according to claim 1, characterized in that, The top of the chamber is equipped with an explosion-proof membrane.

3. The receiving device according to claim 1, characterized in that, The jetting assembly includes a main jetting pipe connected to the main nitrogen pipeline and multiple jetting pipe branches located at the end of the main jetting pipe.

4. The receiving device according to claim 2, characterized in that, The ends of the blowpipe branches are all equipped with Venturi tubes.

5. The receiving device according to claim 1, characterized in that, The filter element group includes multiple filter elements arranged parallel to each other along the height of the chamber. Each filter element has a hollow channel and multiple air holes that connect to the hollow channel. The hollow channel connects to the clean air chamber.

6. The receiving device according to claim 5, characterized in that, The filter element is a sintered metal filter element.

7. The receiving device according to claim 6, characterized in that, The cooling coil has a spiral structure and is laid in the dirty air chamber in the lower space of the filter element group.

8. The receiving device according to claim 1, characterized in that, The discharge hopper has a funnel-shaped structure and a two-stage rotary star-shaped discharge valve at its bottom. An explosion-proof sight glass is installed on the side of the discharge hopper.

9. The receiving device according to claim 1, characterized in that, The outer side of the chamber is equipped with a cooling jacket.

10. A method for collecting materials for preparing carbon nanotubes, characterized in that, The receiving device according to any one of claims 1-9 comprises: The high-temperature process gas used to prepare the carbon nanotube furnace is introduced into the dirty gas chamber through the process gas inlet. The process gas is cooled by the cooling coil. The process gas comes into contact with the filter element group from the outside to the inside and is filtered to obtain purified gas. The purified gas moves sequentially from bottom to top through the filter group into the clean gas chamber, and is then drawn away through the purified gas pipe. The differential pressure sensor on the tube sheet detects the differential pressure value and transmits it to the PLC. The PLC then controls the opening and closing of the purified air pipe and triggers the explosion-proof pulse valve.

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