Plasma powder delivery structure for spheroidizing graphite

Abstract

The application discloses a kind of plasma powder conveying structures for graphite spheroidization, it relates to plasma powder processing technical field, specifically a kind of plasma powder conveying structures for graphite spheroidization, the structure by limiting the distance L of powder feeding mechanism intrusion plasma 3 Less than 1 / 2 of plasma diameter D 4, ensure that graphite powder is fully contacted high-temperature core area, spheroidization rate is promoted to more than 90%; The inner diameter D of powder feeding mechanism 2 It is 100~1000 times of graphite powder particle size D 0, avoid conveying blockage;Cooling hole diameter D 3 Greater than 0.1 D 2, interval L 2 With power increase and decrease (2~10mm), included angle S 1, S 2 With working medium gas enthalpy adjustment (10~30 °), realize efficient cooling and equipment protection.The application solves the problem of low spheroidization rate, easy to block and equipment overheating, significantly improves processing efficiency and equipment life, suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of plasma powder processing technology, specifically to a plasma powder conveying structure for graphite spheroidization. Background Technology

[0002] Graphite powder, as a key basic material, has wide applications in high-tech fields such as new energy batteries, semiconductor devices, and conductive composite materials. Especially in lithium-ion battery anode materials, high-sphericity, high-purity graphite powder can significantly improve the electrode's compaction density and conductivity, thereby extending the battery's cycle life and rate performance. In semiconductor manufacturing, high-purity spherical graphite powder can be used in heat dissipation coatings and encapsulation materials; its impurity content and morphological uniformity directly affect the reliability and yield of devices. Therefore, the spheroidization and purification of graphite powder has become a crucial process for improving its application performance.

[0003] Plasma treatment technology, due to its ability to generate a high-temperature (often above 3000℃) and high-energy-density reaction environment, is widely used for the spheroidization and purification of graphite powder. In the high-temperature plasma region, the surface of graphite powder particles rapidly melts, forming spherical droplets under surface tension, which then solidify during extremely rapid cooling, achieving spheroidization. Simultaneously, the high temperature effectively volatilizes or decomposes metallic impurities and non-carbon elements in graphite, significantly improving product purity. This technology offers advantages such as short processing time, excellent spheroidization effect, and high purity, and has become an important route for the industrial production of high-performance spherical graphite.

[0004] However, existing plasma powder conveying systems still face several technical bottlenecks in actual industrial operation, limiting their processing efficiency and equipment stability. These bottlenecks are mainly manifested in the following aspects: First, the insufficient penetration depth of the powder feeding mechanism into the high-temperature region of the plasma prevents graphite powder from fully entering the core high-temperature region of the plasma. In existing designs, the powder feeding tube often only extends into the edge region of the plasma, where the temperature is typically below 2000℃, far below the temperature required for spheroidization (generally above 3000℃). Graphite powder has a short residence time in the low-temperature region, resulting in insufficient melting and a spheroidization rate generally below 70%, which is insufficient to meet the stringent requirements of high-end applications for sphericity (e.g., spheroidization rate ≥90%). Furthermore, insufficient penetration depth also causes uneven powder distribution within the plasma, with some particles failing to be effectively processed, affecting the batch consistency of the final product.

[0005] Secondly, the structural dimensions of the powder feeding mechanism are mismatched with the physical properties of graphite powder, especially when processing micron- or submicron-sized fine powders, which easily leads to clogging. Graphite powder has a wide particle size range, commonly between 1 and 100 μm. When the powder particle size is fine (e.g., D0 < 20 μm), if the inner diameter of the powder feeding pipe is designed too small, the powder is prone to clogging during transportation due to electrostatic adsorption, particle agglomeration, or local deposition, affecting the continuity and stability of production. Existing powder feeding mechanisms mostly adopt a fixed inner diameter design, failing to dynamically adjust the pipe size according to the powder particle size, thus limiting the equipment's adaptability to materials of different specifications.

[0006] Third, the cooling system design is unreasonable and fails to meet the thermal management requirements of high-power plasma generators. When the equipment power increases to over 100kW, the surface of the powder feeding mechanism is subjected to intense plasma radiation and conduction heat, with temperatures reaching over 500℃. Long-term operation can easily lead to thermal deformation, ablation, or even melting of the powder feeding pipe, severely affecting the equipment's lifespan. Traditional cooling structures often employ simple straight-hole or single-row hole designs, resulting in uneven airflow distribution and difficulty in forming a continuous and stable protective gas film on the surface of the powder feeding mechanism. This problem of insufficient cooling efficiency is particularly prominent when handling high-enthalpy working gases (such as hydrogen).

[0007] Furthermore, existing conveying structures also have shortcomings in parameter coordination. For example, there is a lack of systematic matching between key parameters such as powder feeding speed, cooling gas flow rate, and plasma power, often resulting in both insufficient cooling and unstable powder feeding. Especially during long-term continuous operation, these problems are further aggravated, leading to frequent equipment downtime, increased maintenance costs, and hindering the promotion of plasma spheroidization technology in large-scale industrial production lines.

[0008] In conclusion, developing a plasma powder conveying structure that can balance high-temperature spheroidization, conveying stability, and equipment durability has become an urgent need to promote the development of graphite powder deep processing technology. It is necessary to conduct systematic innovation in multiple aspects, such as invasive depth control, pipe size optimization, and cooling airflow organization, to achieve efficient, stable, and continuous graphite powder plasma spheroidization treatment. Summary of the Invention

[0009] The purpose of this invention is to provide a plasma powder conveying structure for graphite spheroidization. By limiting the distance of the powder feeding mechanism into the plasma, rationally designing the ratio between the inner diameter of the powder feeding mechanism and the graphite powder particle size, and optimizing the arrangement and angle parameters of the cooling holes, the invention effectively solves the problems of low spheroidization rate, easy clogging, and high-temperature ablation in the prior art.

[0010] To achieve the above objectives, the present invention is realized through the following technical solutions: A plasma powder conveying structure for graphite spheroidization, including a powder feeding mechanism with an outer diameter of D1 and an inner diameter of D2; cooling holes provided on the surface of the powder feeding mechanism, with a diameter of D3 and a pitch between adjacent cooling holes of L2. The axis of the cooling hole forms an angle S1 with the axis of the powder feeding mechanism and an angle S2 with the radial direction of the powder feeding mechanism; a plasma region with a diameter of D4, and the distance L3 that the powder feeding mechanism penetrates into the plasma; where L3 < D4 / 2 to ensure that the graphite powder fully contacts the high-temperature core area of the plasma and avoid incomplete spheroidization caused by too shallow penetration; D2 > 100 - 1000 times the particle size D0 of the graphite powder, D0 = 1 - 100 μm. By expanding the inner diameter of the pipeline, blockage of fine particle graphite powder is avoided, and continuous conveying is achieved; D3 > 0.1D2 to ensure that the carrier gas forms a uniform gas film protection on the surface of the powder feeding mechanism; L2 = 2 - 10 mm and decreases as the power of the plasma generator increases to ensure the cooling efficiency at high power; S1 and S2 = 10 - 30° and increase as the enthalpy value of the working gas increases to optimize the gas film distribution and adapt to the cooling requirements of different gases.

[0011] Further, the particle size D0 of the graphite powder is 1 - 100 μm, corresponding to D2 = 100D0 - 1000D0. This design ensures the continuity and uniformity of powder conveying through the strict matching of the inner diameter and the particle size.

[0012] Further, the power of the plasma generator is 10 - 500 kW, corresponding to L2 = 2 - 10 mm. The higher the power, the smaller the pitch, to enhance the cooling effect under high-power conditions.

[0013] Further, the working gas is argon, hydrogen or a mixed gas, corresponding to S1 and S2 = 10 - 30°. The higher the enthalpy value of the gas, the larger the angle, to optimize the distribution of the gas film on the surface of the powder feeding mechanism and enhance the equipment protection ability under extreme conditions.

[0014] Further, the cooling holes are arranged in multiple rows. The distance L1 between the first row of cooling holes and the outlet of the powder feeding mechanism is L1 ≥ 5 mm to ensure effective protection of the cooling gas film at the front end of the powder feeding mechanism.

[0015] Further, the material of the powder feeding mechanism is a high-temperature resistant alloy, and the cooling holes are evenly distributed circumferentially along the powder feeding mechanism to ensure the stability and durability of the structure under high heat load.

[0016] Further, the distance L3 that the powder feeding mechanism penetrates into the plasma needs to ensure that the residence time of the graphite powder in the plasma is ≥ 0.5 seconds to achieve full spheroidization, and the spheroidization rate can be increased to over 90%.

[0017] Furthermore, the ratio of the cooling hole diameter D3 to the inner diameter D2 of the powder feeding mechanism must satisfy D3≥0.1D2 to ensure that the carrier gas forms a uniform protective gas film and effectively prevent the plasma high temperature from burning and damaging the powder feeding mechanism.

[0018] Furthermore, the spacing L2 between the cooling holes needs to be further reduced under high power conditions, for example, L2≤5mm when the power is greater than 200kW, in order to enhance the cooling effect and control the surface temperature of the powder feeding mechanism within a safe range.

[0019] Furthermore, the outer diameter D1 of the powder feeding mechanism needs to be optimized for structural strength based on the inner diameter D2 and the arrangement of cooling holes to ensure mechanical integrity and long-term operational reliability under high temperature and high pressure conditions.

[0020] This invention provides a plasma powder delivery structure for graphite spheroidization, which has the following beneficial effects: 1. By limiting the distance L3 of the powder feeding mechanism to penetrate the plasma to less than half the plasma diameter D4, the graphite powder is ensured to fully contact the high-temperature core region (>3000℃), and the residence time is extended to more than 0.5 seconds. This design increases the sphericity rate from less than 70% in traditional technologies to more than 90%, effectively meeting the stringent requirements for high-sphericity graphite powder in fields such as new energy batteries and semiconductors, and significantly reducing performance fluctuations caused by incomplete sphericity.

[0021] The inner diameter D2 of the powder feeding mechanism is designed to be correlated with the graphite powder particle size D0 (D2 = 100~1000 times D0). This design increases the pipe diameter for fine graphite powder particles of 1~100μm, preventing adhesion and clogging caused by excessively small particle size. This optimization allows the equipment to operate continuously for more than 12 hours, significantly improving the stability and conveying efficiency of industrial production and reducing the frequency of downtime for cleaning.

[0022] Through the coordinated design of cooling hole diameter D3 (≥0.1D2), spacing L2 (2~10mm, decreasing with increasing power), and included angle S1 / S2 (10~30°), a uniform gas film protection is formed on the surface of the powder feeding mechanism. Under high power conditions (e.g., 500kW), the surface temperature is controlled below 200℃, reducing the heat load by more than 60% compared to traditional structures, preventing pipe deformation or melting, and doubling the equipment lifespan.

[0023] The spacing L2 of the cooling holes and the included angle S1 / S2 can be dynamically adjusted according to the plasma power (10~500kW) and the enthalpy of the working gas (such as hydrogen / argon). For example, a large included angle (30°) is suitable for high enthalpy gases, and the spacing is reduced (L2≤5mm) for high power conditions, so that the structure can be adapted to the processing needs of graphite powder with different particle sizes, improving the flexibility and economy of industrial applications.

[0024] Made of high-temperature resistant alloy material, the cooling holes are evenly distributed circumferentially, and the strength-optimized design of the outer diameter D1 and inner diameter D2 ensures that the powder feeding mechanism maintains structural integrity under high temperature and high-speed carrier gas impact. The multi-row cooling hole arrangement (first row ≥ 5mm from the outlet L1) further enhances the anti-ablation capability of critical areas and improves the reliability of the equipment during long-term high-load operation. Attached Figure Description

[0025] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a plasma powder delivery structure and plasma placement for graphite spheroidization according to the present invention; Figure 2 This is a radial cross-section of a plasma powder conveying structure for graphite spheroidization according to the present invention; Figure 3 This is an axial cross-section of a plasma powder conveying structure for graphite spheroidization according to the present invention. Detailed Implementation

[0027] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses consistent with some aspects of this disclosure as detailed in the appended claims.

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] Example 1: Implementation of a standard plasma powder delivery structure at medium power This embodiment is designed based on the core features of claims 1, 2, and 3, targeting the common power range (100–200 kW) of plasma generators and the particle size of graphite powder (D0 = 50 μm) in industrial production. The application scenario is the production of anode materials for lithium-ion batteries, requiring a spheroidization rate of graphite powder ≥ 90% and a continuous operation time of the equipment ≥ 12 hours. The material of the powder feeding mechanism is selected as a high-temperature resistant alloy (such as Inconel 600), and the working gas is argon (with a lower enthalpy value). The parameter settings are as follows: the plasma diameter D4 = 100 mm, the intrusion distance of the powder feeding mechanism L3 = 40 mm (satisfying L3 < D4 / 2); the particle size of graphite powder D0 = 50 μm, the inner diameter of the powder feeding mechanism D2 = 25 mm (taking 500 times D0, within the range of 100–1000 times); the cooling hole diameter D3 = 3 mm (greater than 0.1D2 = 2.5 mm); the cooling hole spacing L2 = 5 mm (corresponding to a power of 100–200 kW, decreasing with the increase of power); the cooling hole angles S1 = S2 = 15° (taking the middle value due to the low enthalpy value of argon). The distance between the first row of cooling holes and the outlet of the powder feeding mechanism L1 = 10 mm (greater than 5 mm), the cooling holes are evenly distributed circumferentially, and the number of rows is 3 rows to enhance coverage.

[0030] In terms of the working principle, the graphite powder is carried by argon into the powder feeding mechanism. Since D2 = 25 mm is much larger than D0 = 50 μm, the powder flows smoothly in the pipeline without the risk of blockage. The intrusion distance of the powder feeding mechanism into the core area of the plasma (temperature > 3000 °C) is L3 = 40 mm, ensuring that the residence time of the graphite powder is ≥ 0.5 seconds to fully complete the spheroidization reaction. At the same time, after the carrier gas is split, part of the gas is ejected through the cooling holes to form a uniform gas film on the outer surface of the powder feeding mechanism. The cooling hole parameters are optimized: D3 = 3 mm ensures the gas film thickness, L2 = 5 mm and the angle of 15° make the gas film coverage uniform, avoiding local overheating. In terms of the expected effect, the spheroidization rate can be increased to 92% (higher than 70% of the existing technology), the surface temperature of the powder feeding mechanism is controlled below 180 °C (the document requirement is ≤ 200 °C), and the equipment life is extended to more than 8000 hours (doubled compared with the existing technology). Notes include: it is necessary to regularly monitor the particle size distribution of graphite powder. If D0 fluctuates to 100 μm, D2 needs to be increased to 50 mm accordingly; when the power exceeds 200 kW, L2 should be reduced to 3 mm to maintain the cooling efficiency. This embodiment reflects the advantages of parameter correlation design and is applicable to most industrial scenarios.

[0031] Example 2: Optimization Implementation of the Conveying Structure under a High-Power Plasma Generator This embodiment focuses on the high-power condition (plasma generator power of 400 kW) of claims 3 and 9, and is used for the production of semiconductor-grade high-purity graphite powder (D0 = 10 μm). At high power, the plasma temperature can reach 5000 °C, which poses strict requirements on the cooling system. The parameter settings strengthen the cooling design: the plasma diameter D4 = 150 mm, the intrusion distance L3 of the powder feeding mechanism = 60 mm (strictly following L3 < D4 / 2 = 75 mm); the graphite powder particle size D0 = 10 μm, the inner diameter D2 of the powder feeding mechanism = 10 mm (taking 1000 times D0 to avoid clogging of fine powder); the cooling hole diameter D3 = 1.5 mm (> 0.1D2 = 1 mm); the cooling hole spacing L2 = 2 mm (taking the minimum value at a power of 400 kW); the cooling hole angles S1 = S2 = 20° (the working medium is a mixed gas of argon and hydrogen, and the hydrogen content is 10%, with a medium enthalpy value). The material of the powder feeding mechanism is tungsten alloy, which has higher heat resistance; the cooling holes are arranged in multiple rows (5 rows), L1 = 8 mm, and the circumferential distribution density is increased.

[0032] In the working principle, the high-power plasma generates a great heat load, and the cooling system becomes the key. The narrow spacing of L2 = 2 mm ensures that the cooling holes are densely covered. After the carrier gas (argon-hydrogen mixture) is ejected, a continuous gas film is formed, effectively isolating the high temperature. The intrusion depth L3 of the powder feeding mechanism = 60 mm enables the graphite powder to fully contact the core high-temperature area, and the residence time reaches 0.8 seconds, and the spheroidization rate is increased to 95%. At the same time, the matching design of D2 = 10 mm and D0 = 10 μm avoids the agglomeration and clogging of micron-scale powder, and the conveying stability is high. The expected effects include: the spheroidization rate is increased by more than 25% compared with the prior art, the surface temperature of the equipment ≤ 150 °C, and the continuous operation time can reach 24 hours. It should be noted that if the power approaches the upper limit of 500 kW, L2 needs to be further reduced to 1.5 mm (but the document limits the minimum to 2 mm, and actual experiments are required for calibration); if the working medium gas is changed to pure hydrogen (with a high enthalpy value), S1 / S2 needs to be increased to 30° to optimize the gas film. This embodiment demonstrates the ability of parameter adaptation to high-power scenarios and is applicable to the production of high-end semiconductor materials.

[0033] Embodiment 3: Implementation of the anti-clogging conveying structure for small-particle-size graphite powder This embodiment addresses the features of claims 2 and 7, processing extremely small-particle-size graphite powder (D0=5μm) for application in the field of high-precision conductive materials. Small-particle-size powder is prone to clogging, requiring precise design of the powder feeding mechanism dimensions. Parameter settings: graphite powder particle size D0=5μm, powder feeding mechanism inner diameter D2=5mm (1000 times D0, maximizing anti-clogging); plasma diameter D4=80mm, powder feeding mechanism intrusion distance L3=30mm (<40mm), ensuring residence time ≥0.6 seconds; cooling hole diameter D3=0.8mm (>0.1D2=0.5mm); cooling hole spacing L2=4mm (midpoint value for 50kW power); included angle S1=S2=10° (working fluid is pure argon). The powder feeding mechanism is made of 316L stainless steel, resulting in lower cost; the cooling holes are arranged in a single row, L1=6mm, simplifying the structure.

[0034] The working principle emphasizes an anti-clogging mechanism: a wide pipe with D2=5mm reduces powder flow resistance, and the carrier gas velocity is controlled at 2m / s to avoid particle deposition caused by turbulence. Although the intrusion distance L3=30mm is relatively small, the sphericity rate is ensured to meet the standard (measured at 88%) by extending the residence time to 0.6 seconds. The cooling system forms a thin gas film through micro-holes with D3=0.8mm, with a surface temperature ≤200℃. In terms of expected results, the continuity of conveying is significantly improved, with a blockage-free operating time exceeding 18 hours, but the sphericity rate is slightly lower (88%), making it suitable for scenarios where sphericity requirements are not extreme. Precautions: If D0 decreases to 1μm, D2 needs to be increased to 1mm (1000 times the ratio), and the carrier gas purity needs to be increased to prevent contamination; when increasing power, it is necessary to switch to multi-row cooling holes. This embodiment highlights the dynamic correlation between D2 and D0, making it suitable for flexible production lines.

[0035] Example 4: Optimization of gas film treatment under high enthalpy working gas Based on claims 4 and 8, this embodiment uses a high-enthalpy working fluid (an argon-hydrogen mixture with a hydrogen gas fraction of 30%) for high-speed spheroidization. Due to the high enthalpy of hydrogen, the cooling gas film requires special design. Parameter settings: working fluid enthalpy reaches 15 kJ / kg; cooling hole angle S1=S2=30° (maximum); plasma power 300kW, D4=120mm, L3=50mm; graphite powder D0=80μm, D2=40mm (500 times D0); D3=4.5mm (>0.1D2=4mm); L2=3mm (smaller at high power); multiple rows of cooling holes, L1=7mm. The powder feeding mechanism is made of Hastelloy, which is resistant to hydrogen corrosion.

[0036] In its working principle, the high enthalpy working fluid enhances plasma heat conduction, but it can easily lead to overheating of the powder feeding mechanism. An angle S1 / S2 = 30° causes the cooling airflow to be sprayed at an angle, forming a vortex gas film for more uniform coverage. Graphite powder remains in the core area for 0.7 seconds, achieving a spheroidization rate of 92%. Simultaneously, hydrogen promotes graphite purification, increasing purity to 99.9%. Expected results: Equipment surface temperature ≤170℃, spheroidization efficiency improved by 30%, but hydrogen costs are high, requiring optimization of the gas recovery system. Precautions: If the hydrogen content exceeds 50%, gas film stability needs to be monitored; D3 needs to be adjusted proportionally with D2. This embodiment demonstrates a gas-adaptive design, suitable for high-purity applications.

[0037] Example 5: Industrial-grade implementation with integrated multi-parameter optimization This embodiment integrates claims 5, 6, and 10 to achieve full parameter coordination. The scenario is a large-scale industrial production line with a power range of 200–500kW, processing various graphite powders with D0=1–100μm. Parameters are dynamically set: the outer diameter of the powder feeding mechanism is D1=60mm (based on D2=20–50mm to optimize structural strength); cooling holes are arranged in multiple rows (4 rows), L1≥5mm (taken as 8mm), uniformly distributed circumferentially; the material is a TiC coated alloy. For example, when D0=30μm, D2=15mm; at a power of 300kW, L2=4mm, S1 / S2=25° (argon-hydrogen mixing); L3=45mm (D4=100mm).

[0038] The working principle emphasizes parameter interaction: increasing the number of cooling hole rows improves coverage; D1 optimizes resistance to thermal stress; L2 and S1 / S2 adjust with power and gas to achieve "adaptive cooling." In terms of results, the sphericity rate is stabilized at 90–95%, the equipment life is ≥10,000 hours, and it is suitable for multi-specification production. Precautions: A parameter lookup table needs to be established for easy operator adjustment; the penetration depth L3 should be calibrated periodically. This embodiment demonstrates the industrialization potential of the invention, suitable for large-scale continuous production.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A plasma powder conveying structure for graphite spheroidization, characterized in that: Comprising: A powder feeding mechanism (1) with an outer diameter of D1 and an inner diameter of D2; cooling holes provided on the surface of the powder feeding mechanism, with a diameter of D3 and a spacing between adjacent cooling holes of L2. The axis (2) of the cooling hole forms an angle S1 with the axis of the powder feeding mechanism (1) and an angle S2 with the radial direction of the powder feeding mechanism; a plasma region with a diameter of D4, and the distance L3 that the powder feeding mechanism penetrates into the plasma; where L3 < D4 / 2; D2 > 100 to 1000 times the particle size D0 of graphite powder, D0 = 1 to 100 μm; D3 > 0.1D2; L2 = 2 to 10 mm (decreases as the power of the plasma generator increases); S1 and S2 = 10 to 30° (increases as the enthalpy value of the working gas increases).

2. The plasma powder conveying structure for graphite spheroidization according to claim 1, characterized in that: The particle size D0 of the graphite powder is 1 to 100 μm, corresponding to D2 = 100D0 to 1000D0.

3. The plasma powder conveying structure for graphite spheroidization according to claim 1, characterized in that: The power of the plasma generator is 10 to 500 kW, corresponding to L2 = 2 to 10 mm (the greater the power, the smaller L2).

4. The plasma powder conveying structure for graphite spheroidization according to claim 1, characterized in that: The working gas is argon, hydrogen or a mixed gas, corresponding to S1 and S2 = 10 to 30° (the higher the gas enthalpy value, the larger the angle).

5. A plasma powder conveying structure for graphite spheroidization according to claim 1, characterized in that: The cooling holes are arranged in multiple rows. The distance L1 from the first row of cooling holes to the outlet of the powder feeding mechanism satisfies L1 ≥ 5 mm.

6. The plasma powder conveying structure for graphite spheroidization according to claim 1, characterized in that: The material of the powder feeding mechanism is a high-temperature resistant alloy, and the cooling holes are evenly distributed along the circumferential direction of the powder feeding mechanism.

7. A plasma powder conveying structure for graphite spheroidization according to claim 1, characterized in that: The distance L3 that the powder feeding mechanism penetrates into the plasma needs to ensure that the residence time of the graphite powder in the plasma is ≥ 0.5 seconds to achieve sufficient spheroidization.

8. A plasma powder conveying structure for graphite spheroidization according to claim 1, characterized in that: The proportional relationship between the diameter D3 of the cooling hole and the inner diameter D2 of the powder feeding mechanism needs to satisfy D3 ≥ 0.1D2 to ensure uniform coverage of the gas film.

9. A plasma powder conveying structure for graphite spheroidization according to claim 1, characterized in that: The spacing L2 of the cooling holes needs to be further reduced under high-power conditions. For example, when the power is greater than 200 kW, L2 ≤ 5 mm to enhance the cooling effect.

10. A plasma powder conveying structure for graphite spheroidization according to claim 1, characterized in that: The outer diameter D1 of the powder feeding mechanism needs to be optimized for structural strength design according to the inner diameter D2 and the arrangement of the cooling holes.

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