Reaction system for micro-nano powder surface deposition coating and operation method

Abstract

The invention discloses a reaction system for micro-nano powder surface deposition coating. The reaction system comprises a fluidized bed reactor, a coil pipe, a supply device, a heating device and a collecting device, the fluidized bed reactor is provided with a reaction cavity, and an input port and an output port communicated with the reaction cavity; the coil pipe is spirally wound in the reaction cavity; the supply device is connected with the coil pipe so as to be suitable for conveying the micro-nano powder, the precursor and the fluidizing gas to the coil pipe; the heating device is arranged on the fluidized bed reactor to heat the fluidized bed reactor; the collecting device is connected with the fluidized bed reactor to be suitable for collecting reacted products. According to the reaction system, the retention time of the micro-nano powder and the precursor in the reaction cavity can be prolonged, so that the deposition coating effect is improved, and the coating uniformity of the surface of the micro-nano powder is better.

Description

Technical Field

[0001] The invention relates to the technical field of micro-nano powder coating, and in particular to a reaction system and an operation method for deposition coating on the surface of micro-nano powder. Background Art

[0002] Particle coating is an effective means to achieve particle dispersion, modification, isolation and transportation. Among the related technologies of particle coating, fluidized bed technology has been widely used in particle coating due to its advantages such as high heat and mass transfer efficiency and uniform reaction. Under the action of fluid, the particles show the properties of fluid, making the contact between particles and fluid more efficient, and it has the characteristics of large-scale production and continuous production process. Chemical vapor deposition is a widely used processing technology that can deposit one or more gaseous substances on the surface of the substrate to form a thin film. According to the fluidization ability of the particles, chemical vapor deposition can be combined with a fluidized bed to form a fluidized bed-chemical vapor deposition technology, which has many advantages, specifically high conversion rate of gaseous precursors to solids, high uniformity of chemical properties, morphology and thickness of the particle coating layer, and low production cost.

[0003] However, in the chemical vapor deposition coating of micro-nano powders, it is difficult to achieve uniform coating due to the small particle size of the powder and poor fluidization state. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to provide a reaction system for deposition coating of micro-nano powder surface, which can increase the residence time of micro-nano powder and precursor in the fluidized bed reactor by setting a coil, thereby improving the deposition coating effect.

[0005] The present invention proposes a reaction system for deposition and coating of micro-nano powder surfaces, the reaction system comprising a fluidized bed reactor, a coil, a supply device, a heating device and a collecting device; the fluidized bed reactor is formed with a reaction chamber and an input port and an output port connected to the reaction chamber; the coil is spirally wound in the reaction chamber; the supply device is connected to the coil to be suitable for conveying micro-nano powders, precursors and fluidizing gas to the coil; the heating device is arranged in the fluidized bed reactor to be suitable for heating the fluidized bed reactor; the collecting device is connected to the fluidized bed reactor to be suitable for collecting the products after the reaction.

[0006] According to an embodiment of the present invention, a coil is provided in the reaction chamber of the fluidized bed reactor, and the micro-nano powder and the precursor move and react in the coil. Since the coil has a large extension length in a limited space, the travel of the micro-nano powder and the precursor in the reaction chamber can be increased, thereby extending the time that the micro-nano powder and the precursor stay in the reaction chamber, thereby improving the deposition coating effect and making the uniformity of the micro-nano powder surface coating better. In addition, since the inner diameter of the coil is small, the gas flow rate in the coil is uniform and stable, which can avoid the occurrence of channel flow, slugging and other phenomena, and can further improve the deposition coating effect.

[0007] According to some embodiments of the present invention, the coil includes a spiral section and a straight pipe section, one end of the straight pipe section is connected to the spiral section, and the other end of the straight pipe section extends out of the reaction chamber through the input port to be suitable for connecting with the supply device; the spiral section is arranged in the reaction chamber.

[0008] According to some embodiments of the present invention, the spiral section is communicated with a collecting device; or the outlet of the spiral section is adjacent to the output port, and the output port is communicated with the collecting device.

[0009] According to some embodiments of the present invention, the helix angle of the coil is α, and satisfies 2°≤α≤15°.

[0010] According to some embodiments of the present invention, the axial length of the coil is L1, the axial length of the reaction chamber is L2, and 0.9≤L1 / L2<1 is satisfied.

[0011] According to some embodiments of the present invention, the diameter of the coil is D, and satisfies 15 mm≤D≤160 mm, and 6≤L1 / D≤12.

[0012] According to some embodiments of the present invention, the reaction system further comprises a gas pipeline, one end of which is connected to the input port, and the other end of which is connected to the supply device so as to be suitable for delivering gas into the reaction chamber.

[0013] According to some embodiments of the present invention, the reaction system further comprises a cooling device, and the cooling device is disposed in the fluidized bed reactor for cooling the fluidized bed reactor.

[0014] According to some embodiments of the present invention, the reaction system is applied to prepare nuclear fuel elements or battery electrode materials.

[0015] The present invention also proposes an operating method of the above-mentioned reaction system for deposition and coating of micro-nano powder surfaces, the operating method comprising the following steps:

[0016] S1: Assemble the reaction system and perform airtightness test;

[0017] S2: Set the temperature environment and gas environment required for the reaction;

[0018] S3: introducing micro-nano powders and precursors into the reaction system for deposition and coating, and collecting the products.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0021] Figure 1 is a schematic diagram of a reaction system for deposition and coating of micro-nano powder surfaces according to some embodiments of the present invention;

[0022] Figure 2 is a schematic diagram of the structure of the coil of the reaction system according to some embodiments of the present invention;

[0023] Figure 3 is a SEM image of the product of Experiment 1 in which the reaction system of the present invention is used for deposition coating;

[0024] Figure 4 is a SEM image of the product of Experiment 2 in which the reaction system of the present invention is used for deposition coating;

[0025] Figure 5 It is a SEM picture of the product of Experiment 3 in which the reaction system of the present invention is used for deposition coating.

[0026] Reference numerals:

[0027] Fluidized bed reactor 10; reaction chamber 11; input port 12; output port 13;

[0028] Coil 20; spiral section 21; straight pipe section 22;

[0029] Supply device 30; solid powder feeder 31; gas transport device 32; transport pipeline 33;

[0030] Heating device 40; collecting device 50; gas pipeline 60. DETAILED DESCRIPTION

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0032] Reference below Figure 1-Figure 2 A reaction system for deposition and coating of micro-nano powder surfaces according to an embodiment of the present invention is described.

[0033] The present invention proposes a reaction system for deposition and coating of micro-nano powder surfaces, the reaction system comprising a fluidized bed reactor 10, a coil 20, a supply device 30, a heating device 40 and a collecting device 50; the fluidized bed reactor 10 is formed with a reaction chamber 11 and an input port 12 and an output port 13 connected to the reaction chamber; the coil 20 is spirally wound in the reaction chamber 11; the supply device 30 is connected to the coil 20 to be suitable for conveying micro-nano powders, precursors and fluidizing gas to the coil 20; the heating device 40 is arranged on the fluidized bed reactor 10 to be suitable for heating the fluidized bed reactor 10; the collecting device 50 is connected to the fluidized bed reactor 10 to be suitable for collecting the products after the reaction.

[0034] According to the reaction system of the present invention, the fluidized bed reactor 10 provides a reaction place with fluidized conditions; the coil 20 is arranged in the reaction chamber 11 of the fluidized bed reactor 10, and the heating device 40 is arranged in the fluidized bed reactor 10, which can heat the fluidized bed reactor 10 to form a temperature environment required for deposition and coating in the reaction chamber 11 and the coil 20; the supply device 30 is connected to the coil 20, and the supply device 30 can provide micro-nano powders, precursors and fluidizing gas to the coil 20. It should be noted that the micro-nano powder materials can be transported by the carrier gas, and the carrier gas can be the same as the fluidizing gas. The precursor is in gaseous state and is transported together with the fluidizing gas; the micro-nano powders and precursors flow and move in the coil 20 driven by the carrier gas and the fluidizing gas, and during the movement, the precursor can react and be deposited and coated on the surface of the micro-nano powder; the collecting device 50 is connected to the fluidized bed reactor 10 to collect the products after the reaction.

[0035] According to an embodiment of the present invention, a coil 20 is provided in the reaction chamber 11 of the fluidized bed reactor 10, and the micro-nano powder and the precursor move and react in the coil 20. Since the coil 20 has a large extension length in a limited space, the travel of the micro-nano powder and the precursor in the reaction chamber 11 can be increased, thereby extending the time for the micro-nano powder and the precursor to stay in the reaction chamber 11, thereby improving the deposition coating effect and making the uniformity of the micro-nano powder surface coating better. In addition, since the inner diameter of the coil 20 is small, the gas flow rate in the coil 20 is uniform and stable, which can avoid the occurrence of channel flow, slugging and other phenomena, and can further improve the deposition coating effect.

[0036] In some embodiments, the input port 12 is disposed at the bottom of the fluidized bed reactor, and the output port 13 is disposed at the top of the fluidized bed reactor, so that the micro-nano powders and precursors continue to move upward driven by the gas to avoid accumulation due to gravity.

[0037] According to some embodiments of the present invention, the coil 20 includes a spiral section 21 and a straight section 22, one end of the straight section 22 is connected to the spiral section 21, and the other end of the straight section 22 extends out of the reaction chamber 11 through the input port 12 to be suitable for connecting with the supply device 30; the spiral section 21 is arranged in the reaction chamber 11. In this embodiment, Figure 1 , Figure 2 As shown, part of the straight pipe section 22 extends out of the reaction chamber 11 through the input port 12, so that the coil 20 is easily connected to the supply device 30, so that the supply device 30 can transport micro-nano powders, precursors and fluidizing gas to the coil 20. In some embodiments, the length of the straight pipe section 22 is 50 mm to 1000 mm.

[0038] According to some embodiments of the present invention, the spiral section 21 is connected to the collecting device 50 through a connecting pipeline; or the outlet of the spiral section 21 is adjacent to the output port 13, and the output port 13 is connected to the collecting device 50. In this embodiment, the spiral section 21 can be connected to the collecting device 50 through a connecting pipeline, and the micro-nano powder and precursor can be directly moved to the collecting device 50 after flowing out of the coil 20 to complete the collection of the product. One end of the spiral section 21 can also be open in the reaction chamber 11, and its outlet is arranged adjacent to the output port 13, and the output port 13 is connected to the collecting device 50. After flowing out of the coil 20, the micro-nano powder and precursor can continue to flow in the reaction chamber 11 until they move to the collecting device 50, and the collecting device 50 completes the collection of the product. Further, the outlet of the spiral section 21 can be directly opposite to and close to the output port 13, and the micro-nano powder and precursor can flow directly to the collecting device 50 after flowing out of the coil 20. In some embodiments, the spiral section 21 can be close to the output port 13 through a transfer pipeline.

[0039] According to some embodiments of the present invention, the helix angle of the coil 20 is α, and satisfies 2°≤α≤15°. In this embodiment, the helix angle of the coil 20 is set to the above angle range, so that the coil 20 can have more winding turns in the limited space of the reaction chamber 11, thereby making the extension length of the coil 20 longer and prolonging the time that the micro-nano powder and precursor stay in the reaction chamber 11.

[0040] According to some embodiments of the present invention, the axial length of the coil 20 is L1, and the axial length of the reaction chamber 11 is L2, and they satisfy 0.9≤L1:L2<1. In this embodiment, the axial length of the coil 20 refers to the length of the coil 20 distributed along the axial direction of the fluidized bed reactor 10, and the ratio of the axial length of the coil 20 to the axial length of the reaction chamber 11 satisfies 0.9≤L1:L2<1, which can make the distribution range of the coil 20 in the reaction chamber 11 larger, and can make the coil 20 have more winding turns in the limited space of the reaction chamber 11, so that the extension length of the coil 20 can be longer, and the residence time of the micro-nano powder and the precursor in the reaction chamber 11 can be extended; at the same time, the coil 20 can be placed in the constant temperature area within the radiation range of the heating device 40 to maintain stable reaction conditions.

[0041] According to some embodiments of the present invention, the diameter of the coil 20 is D, and satisfies 15mm≤D≤160mm, 6≤L1:D≤12. In this embodiment, by limiting the ratio of the diameter of the coil 20 to the axial length, it is possible to ensure that the coil 20 has a sufficient number of winding turns, avoid the problem of insufficient winding turns caused by the excessive diameter of the coil 20 in a limited space, and make the coil 20 have a sufficient extension length to extend the time that the micro-nano powder and precursor stay in the reaction chamber 11. The diameter of the coil 20 can be selected according to the size of the fluidized bed reactor 10 in the actual scene, combined with the actual conditions such as the gas flow rate. In some embodiments, in actual application, the diameter D of the coil 20 satisfies 15mm≤D≤160mm. Further, in some embodiments, the inner diameter D1 and outer diameter D2 of the coil 20 satisfy 2mm≤D1≤15mm, 3mm≤D2≤20mm.

[0042] In some embodiments, the number of coils of the coil 20 is several tens. In some embodiments, the outer walls of two adjacent coils 20 are in close contact.

[0043] It should be noted that, during the deposition coating, in order to improve the reaction effect, a gas atmosphere needs to be maintained in the reaction chamber 11 .

[0044] In view of the above requirements, according to some embodiments of the present invention, the reaction system further includes a gas pipeline 60, one end of which is connected to the input port 12, and the other end of the gas pipeline 60 is connected to the supply device 30, so as to be suitable for conveying gas into the reaction chamber 11. In this embodiment, by providing the gas pipeline 60, the fluidizing gas can be continuously introduced into the reaction chamber 11, and the fluidizing gas can maintain a stable gas atmosphere in the reaction chamber 11, and at the same time, the temperature distribution in the reaction chamber can be made more uniform, which is conducive to improving the reaction effect.

[0045] Furthermore, in the embodiment where one end of the spiral section 21 is open in the reaction chamber 11 near the output port 13, the fluidizing gas has a certain power to drive the micro-nano powders and precursors to flow in a fixed direction, so as to promote the micro-nano powders after deposition and coating to enter the collection device 50 for collection; at the same time, the micro-nano powders and precursors can be prevented from accumulating in the reaction chamber 11. In addition, the fluidizing gas in the reaction chamber 11 is controllable, and its flow rate can be adjusted.

[0046] In some embodiments, the inner diameter of part of the wall of the reaction chamber 11 gradually increases in the vertical direction. According to the basic principles of fluid mechanics, the larger the cross-sectional area of ​​the flow, the smaller the flow rate, so the flow rate of the fluidizing gas can be slowed down to achieve stable delivery.

[0047] In some embodiments, the straight pipe section 22 extends out of the reaction chamber 11 through the input port 12, and the gas pipeline 60 is arranged around the outer circumference of the straight pipe section 22, so as to be suitable for uniformly inputting the fluidizing gas into the reaction chamber 11 in the circumferential direction. In some embodiments, the gas pipeline 60 includes an inner pipe and an outer pipe, the outer pipe is connected to the input port 12 of the fluidized bed reactor 10, the inner pipe is sleeved between the outer pipe and the straight pipe section 22, and the fluidizing gas is transported in the gap channel between the inner pipe and the outer pipe.

[0048] According to some embodiments of the present invention, the reaction system further comprises a cooling device, which is disposed in the fluidized bed reactor 10 for cooling the fluidized bed reactor 10. In this embodiment, the cooling device is disposed in the fluidized bed reactor 10, and the fluidized bed reactor 10 can be cooled in time.

[0049] It should be noted that in the related technology of deposition coating, the supply device 30 needs to transport micro-nano powders and precursors to the fluidized bed reactor 10, and the supply device 30 includes a storage and transportation device for the micro-nano powders and precursors.

[0050] In some embodiments, the supply device 30 includes a solid powder feeder 31 , a gas transport device 32 , and a transport pipeline 33 , and the transport pipeline 33 is in communication with the coil 20 .

[0051] The solid powder feeder 31 includes a turntable, a controller, a powder bin, a pressure gauge, a stepper motor and a quantitative powder feeding device. The solid powder feeder 31 is used to quantitatively transport micro-nano powder materials to the coil 20. The micro-nano powder materials are driven by the carrier gas to move in the transport pipeline 33.

[0052] The gas transport device 32 can provide power for gas transport. On the one hand, the carrier gas is transported from a storage device such as a gas cylinder to flow through the pipeline, valve, flow meter and solid powder feeder 31, and the micro-nano powder material is transported into the transport pipeline 33; on the other hand, the precursor and fluidizing gas are transported from a storage device such as a gas cylinder to enter the transport pipeline 33; on the other hand, the fluidizing gas is transported from a storage device such as a gas cylinder to enter the gas pipeline 60 or the transport pipeline 33. In some embodiments, the gas transport device 32 is provided with a gas drying system and a digital operating system.

[0053] In some embodiments, the collecting device 50 is configured as a cyclone separator and is configured to have upper air intake to collect the deposition and coating products of the micro-nano powders.

[0054] The present invention also proposes an operating method of a reaction system for deposition and coating of micro-nano powder surfaces, the operating method comprising the following steps:

[0055] S1: Assemble the reaction system and perform airtightness test;

[0056] S2: Set the temperature environment and gas environment required for the reaction;

[0057] S3: introducing micro-nano powders and precursors into the reaction system for deposition and coating, and collecting the products.

[0058] According to the operation method of the present invention, step S1 specifically includes: pre-connecting the supply device 30, the gas pipeline 60 and the coil 20, performing an airtightness inspection, and detecting the transportation of the micro-nano powder; after the inspection, installing the gas pipeline 60 and the coil 20 in the fluidized bed reactor 10 to complete the assembly of the reaction system. Step S1 can be used to inspect the structural reliability of the reaction system, troubleshoot problems such as gas leakage, and ensure that the subsequent reaction process proceeds smoothly.

[0059] According to the operating method of the present invention, step S2 specifically includes: using a vacuum pump to evacuate the reaction chamber 11 of the fluidized bed reactor 10 to a vacuum state, inputting fluidizing gas into the transport pipeline 33 and the gas pipeline 60, and adjusting the gas flow rate to maintain a gas atmosphere in the reaction chamber 11 and the coil 20; turning on the heating device 40, adjusting the temperature in the reaction chamber 11 of the fluidized bed reactor 10 and keeping it warm. Step S2 can create the environmental conditions required for the reaction to ensure that the reaction process can proceed stably. It should be noted that in order to improve the safety of the reaction system, the cooling device can be turned on before the start of step S2 so that it remains turned on during the operation.

[0060] According to the operation method of the present invention, step S3 specifically includes: introducing a gaseous precursor and a fluidizing gas into the coil 20; then starting the solid powder feeder, adjusting the powder feeding speed of the quantitative powder feeding device and the gas velocity of the carrier gas to adjust the transport speed of the micro-nano powder material, so that the micro-nano powder material is introduced into the coil 20 through the transport pipeline 33; in the coil 20, the gaseous precursor decomposes and deposits on the surface of the micro-nano powder material under a certain temperature to form a coating layer; after the coating is completed, the gas transport device 32 is operated to stop transporting the gaseous precursor and the micro-nano powder material; the heating device 40 is turned off, and the fluidized bed reactor 10 is cooled by the cooling device, and the product is obtained from the collection device 50 after the temperature of the fluidized bed reactor 10 drops to room temperature. The deposition coating is achieved through step S3 and the coated micro-nano powder product is obtained. After step S3 is completed, the cooling device is turned off.

[0061] In order to achieve long-term reuse of the reaction system, after the deposition coating is completed, the operation method also includes step S4: removing the gas pipeline 60 and the coil 20 from the fluidized bed reactor 10, checking the condition of the product and the coil 20 and other structures, and cleaning the structure to wait for the next experiment.

[0062] When the operating method of the present invention is applied in a specific application, the micro-nano powder, precursor, fluidizing gas, material of carrier gas, reaction temperature and gas transport speed are selected and adjusted according to actual conditions.

[0063] In order to test the performance of the reaction system of the present invention, the following experiment was conducted according to the reaction system and operation method for deposition and coating of micro-nano powder surfaces of the present invention:

[0064] Comparative experiment: Preparation of carbon coating by pyrolysis of propylene gas at 850°C

[0065] The reaction system used in this experiment does not have the coil 20 structure. The silicon dioxide powder used in this experiment has an initial particle size of 10 μm and a quantitative powder delivery rate of 0.7 g / min. The experiment lasted for 60 minutes, of which the heat preservation time was 10 minutes.

[0066] After testing, it was found that due to insufficient residence time of the powder, only about 40% of the silica powder in the product obtained in this experiment obtained a carbon coating layer, with an average particle size of 80 μm, and the carbon content of the successfully coated powder was about 10%.

[0067] Experiment 1: Preparation of carbon coating by pyrolysis of propylene gas at 900°C

[0068] In the reaction system used in this experiment, the inner diameter of the coil 20 is 8 mm, the outer diameter is 10 mm, the helix angle is 6°, and the diameter is 70 mm. The particles to be coated used in this experiment are powdered alumina with an initial particle size of 10 μm, and the powder quantitative delivery speed is 0.6 g / min. The experiment lasted for 50 minutes, of which the insulation time was 5 minutes.

[0069] During the experiment, the coil 20 stably transported gas and powder without any blockage. After cooling to room temperature, the coil 20 was checked and found to be in good structure without obvious deformation. Only a small amount of product appeared near the outlet end, which could be reused after simple polishing. The product obtained in this experiment was a core-shell structure powder, with the core being alumina and the coating being carbon. The SEM image obtained by electron microscopy is shown in the figure below. Figure 3 As shown. According to the test, the average particle size of the core-shell structure powder is 50μm, the carbon coating layer is uniform, and the carbon content is about 8%. Figure 3 It can be seen that the carbon coating layer is uniform and thin, and the powder undergoes secondary agglomeration under the action of gas.

[0070] Experiment 2: Preparation of carbon coating by pyrolysis of propylene gas at 900°C

[0071] In the reaction system used in this experiment, the coil 20 is 4mm, the outer diameter is 6mm, the helix angle is 6°, and the diameter is 40mm. The particles to be coated in this experiment are aluminum oxide powders with an initial particle size of 10μm, and the quantitative powder delivery rate is 0.6g / min. The experiment lasted for 85 minutes, of which the insulation time was 20 minutes.

[0072] During the experiment, the coil 20 stably transported gas and powder without any blockage. After cooling to room temperature, the coil 20 was checked and found to be in good structure without obvious deformation. Only a small amount of product appeared near the outlet end, which could be reused after simple polishing. The product obtained in this experiment was a core-shell structure powder, with the core being aluminum oxide and the coating being carbon. The SEM image obtained by electron microscopy is shown in the figure. Figure 4 As shown. According to the test, the average particle size of the core-shell structure powder is 100μm, the carbon coating layer is uniform, and the carbon content is about 18%. Figure 4 It can be seen that the carbon coating layer is uniform and relatively thick, and the powder undergoes obvious secondary agglomeration under the action of gas.

[0073] Experiment 3: Preparation of carbon coating by pyrolysis of propylene gas at 800°C

[0074] In the reaction system used in this experiment, the coil 20 is 4mm, the outer diameter is 6mm, the helix angle is 6°, and the diameter is 40mm. The particles to be coated in this experiment are silica powders with an initial particle size of less than 30μm, the sphericity of the powder is greater than 95%, and the quantitative powder delivery speed is 1.0g / min. The experiment lasted for 60 minutes, of which the insulation time was 10 minutes.

[0075] During the experiment, the coil 20 stably transported gas and powder without any blockage. After cooling to room temperature, the coil 20 was checked and found to be in good structure without obvious deformation. Only a small amount of product appeared near the outlet end, which could be reused after simple polishing. The product obtained in this experiment was a core-shell structure powder, with the core being silicon dioxide and the coating being carbon. The SEM image obtained by electron microscopy is shown in the figure. Figure 5 As shown. According to the test, the average particle size of the core-shell structure powder is 20μm, the carbon coating layer is uniform, and the carbon content is about 10%. Figure 4 It can be seen that the carbon coating layer is uniform and thin, and the dispersion and sphericity of the original powder are well preserved.

[0076] Experiment 4: Preparation of carbon coating by pyrolysis of propylene gas at 950°C

[0077] In the reaction system used in this experiment, the coil 20 is 4mm, the outer diameter is 6mm, the helix angle is 5°, and the diameter is 50mm. The particles to be coated in this experiment are pure silicon powder with an initial particle size of less than 5μm, and the quantitative powder delivery rate is 0.8g / min. The experiment lasted for 60 minutes, of which the insulation time was 10 minutes.

[0078] During the experiment, the coil 20 stably transported gas and powder without plugging. After cooling to room temperature, the coil 20 was checked and found to be in good structure without obvious deformation. Only a trace amount of product appeared near the outlet end, which could be reused after simple grinding. The product obtained in this experiment was a core-shell structure powder, with silicon as the core and carbon as the coating. After testing, the average particle size of the core-shell structure powder was 20μm, the carbon coating was uniform, and the carbon content was about 12%.

[0079] Experiment 5: Preparation of carbon coating by pyrolysis of propylene gas at 850°C

[0080] In the reaction system used in this experiment, the coil 20 is 6mm, the outer diameter is 8mm, the helix angle is 4°, and the diameter is 30mm. The particles to be coated in this experiment are silica powders with an initial particle size of 20μm, and the quantitative powder delivery rate is 1.0g / min. The experiment lasted for 90 minutes, of which the insulation time was 30 minutes.

[0081] During the experiment, the coil 20 stably transported gas and powder without plugging. After cooling to room temperature, the coil 20 was checked and found to be in good structure without obvious deformation. Only a trace amount of product appeared near the outlet end, which could be reused after simple grinding. The product obtained in this experiment was a core-shell structure powder, with a core of silicon dioxide and a coating of carbon. After testing, the average particle size of the core-shell structure powder was 50μm, the carbon coating was uniform, and the carbon content was about 20%.

[0082] By comparing the above experimental results, it can be proved that the reaction system for deposition coating on the surface of micro-nano powders of the present invention can indeed improve the deposition coating effect on the surface of micro-nano powders, making the uniformity of the micro-nano powder surface coating better; and the reaction system of the present invention has good performance and can realize continuous, long-term and stable preparation of products.

[0083] The reaction system for deposition and coating of micro-nano powder surfaces according to the present invention is mainly used for coating of micro-nano powders, and can also be used for preparing nuclear fuel elements or battery electrode materials.

[0084] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0085] In the description of the present invention, "first feature" or "second feature" may include one or more of the features.

[0086] In the description of the present invention, "plurality" means two or more.

[0087] In the description of the present invention, a first feature being “on” or “under” a second feature may include that the first and second features are directly in contact with each other, or may include that the first and second features are not in direct contact with each other but are in contact with each other via another feature therebetween.

[0088] In the description of the present invention, “on”, “over” and “above” a first feature from a second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0089] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0090] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A reaction system for deposition and coating of micro-nano powder surfaces, characterized in that: include: A fluidized bed reactor, wherein the fluidized bed reactor is formed with a reaction chamber and an input port and an output port communicated with the reaction chamber; A coil, the coil spirally surrounding the reaction chamber; A supply device, the supply device is connected to the coil so as to be suitable for conveying micro-nano powders, precursors and fluidizing gas to the coil; A heating device, the heating device is arranged in the fluidized bed reactor and is suitable for heating the fluidized bed reactor; A collecting device is connected to the fluidized bed reactor to collect the product after the reaction.

2. The reaction system for deposition and coating of micro-nano powder surfaces according to claim 1, characterized in that: The coil comprises: A spiral section and a straight pipe section, one end of the straight pipe section is connected to the spiral section, and the other end of the straight pipe section extends out of the reaction chamber through the input port to be suitable for connecting with the supply device; the spiral section is arranged in the reaction chamber.

3. The reaction system for deposition and coating of micro-nano powder surfaces according to claim 2, characterized in that: The spiral section is connected to the collecting device via a connecting pipeline; or The outlet of the spiral section is adjacent to the output port, and the output port is communicated with the collecting device.

4. The reaction system for deposition and coating of micro-nano powder surfaces according to claim 1, characterized in that: The helix angle of the coil is α, and satisfies 2°≤α≤15°.

5. The reaction system for deposition and coating of micro-nano powder surfaces according to claim 1, characterized in that: The axial length of the coil is L1, the axial length of the reaction chamber is L2, and 0.9≤L1 / L2<1 is satisfied.

6. The reaction system for deposition and coating of micro-nano powder surfaces according to claim 5, characterized in that: The diameter of the coil is D, and satisfies 15mm≤D≤160mm, 6≤L1 / D≤12.

7. The reaction system for deposition and coating of micro-nano powder surfaces according to claim 1, characterized in that: Also includes: A gas pipeline, one end of which is communicated with the input port, and the other end of which is connected to the supply device, so as to be suitable for conveying gas into the reaction chamber.

8. The reaction system for deposition and coating of micro-nano powder surfaces according to claim 1, characterized in that: Also includes: A cooling device is provided in the fluidized bed reactor for cooling the fluidized bed reactor.

9. The reaction system for deposition and coating of micro-nano powder surfaces according to any one of claims 1 to 8, characterized in that: The reaction system is used for preparing nuclear fuel elements or battery electrode materials.

10. An operating method of a reaction system for deposition and coating of micro-nano powder surfaces according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: Assemble the reaction system and perform airtightness test; S2: Set the temperature environment and gas environment required for the reaction; S3: introducing micro-nano powders and precursors into the reaction system for deposition and coating, and collecting the products.

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