Fluidized bed vapor deposition furnace

Abstract

The present invention discloses a fluidized bed vapor deposition furnace, comprising a furnace body with a closed furnace and a heating device for heating the closed furnace, the furnace body is connected with a feeding device for feeding materials into the closed furnace, a discharging device for discharging materials from the closed furnace, and an exhaust device for discharging gas from the closed furnace, and a gas nozzle for spraying gas into the furnace to blow the materials upward is provided at the bottom of the closed furnace. The fluidized bed vapor deposition furnace has the advantages of simple structure, low cost, easy operation, convenient maintenance, high coating efficiency, good coating effect, etc.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment kilns, and in particular to a fluidized bed vapor deposition furnace. Background Art

[0002] Silicon-based negative electrode materials are considered to be the most promising negative electrode materials for the next generation of lithium-ion batteries due to their high capacity, low lithium desorption potential, and low cost. However, there are still some problems in the large-scale application of silicon-based negative electrode materials, one of which is how to solve the problem of particle pulverization, shedding, and electrochemical performance failure caused by volume expansion and contraction of silicon-based negative electrode materials when lithium is inserted and removed during the charging and discharging process of lithium-ion batteries.

[0003] In order to improve the cycle performance of silicon-based negative electrode materials and enhance the structural stability of materials during the cycle, the production of silicon-carbon negative electrode materials by vapor deposition is currently generally considered to be the most likely method to achieve industrialization. That is, in a high temperature environment, nitrogen is used as a protective gas, and methane or other hydrocarbon gases decompose carbon atoms, which are deposited on the surface of micron-sized silicon oxide particles to form a carbon coating layer.

[0004] At present, the equipment used for producing materials by vapor deposition is a rotary vapor deposition furnace, which is essentially a rotary kiln, and has the problems of long coating time, uneven coating, and low efficiency. The above problems are particularly prominent when the matrix such as micron-sized silicon oxide is an ultrafine powder that is prone to inter-particle agglomeration. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a boiling vapor deposition furnace with a simple structure, low cost, easy operation, convenient maintenance, high coating efficiency and good coating effect.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A boiling vapor deposition furnace comprises a furnace body with a closed furnace chamber and a heating device for heating the closed furnace chamber. The furnace body is connected to a feeding device for feeding materials into the closed furnace chamber, a discharging device for discharging materials from the closed furnace chamber and an exhaust device for discharging gases from the closed furnace chamber. The bottom of the closed furnace chamber is provided with a gas nozzle for spraying gas into the furnace chamber to blow the materials upwards.

[0008] As a further improvement of the above technical solution:

[0009] A material guide pipe is installed in the closed furnace, and an annular material drop space is formed between the material guide pipe and the inner wall of the closed furnace. The material guide pipe has a material guide channel that runs through the upper and lower parts to allow the material blown by the air nozzle to pass through. The lower end of the material guide channel is located directly above the air nozzle, and a distance is left between the upper end of the material guide channel and the top surface of the furnace.

[0010] The material guiding channel is cylindrical.

[0011] The surface of the air nozzle is provided with a central area and an annular area surrounding the central area, the central area is provided with more than one first nozzle, the annular area is provided with multiple second nozzles, and the air flow velocity ejected from the first nozzle is greater than the air flow velocity ejected from the second nozzle.

[0012] The air nozzle has an air cavity with an air inlet, all the first ejection ports and all the second ejection ports are connected to the air cavity, and an opening area of ​​the first ejection port is smaller than an opening area of ​​the second ejection port.

[0013] The communication port between the exhaust device and the closed furnace is located above the upper port of the material guiding channel.

[0014] The gas nozzle is located in the middle of the bottom surface of the closed furnace, and the bottom surface of the closed furnace is inclined and extends upward in a direction away from the gas nozzle.

[0015] The feeding device is a pneumatic feeding device, which includes a positive pressure sending bin, which is connected to a gas source pipeline for connecting to a pressure gas source, and the positive pressure sending bin is connected to a closed furnace through a feeding pipeline. A feeding control valve for controlling the on-off of the feeding pipeline is provided on the feeding pipeline, and the positive pressure sending bin is also provided with an openable and closable feeding port for feeding.

[0016] The discharging device includes a receiving silo and a negative pressure blower connected to the receiving silo. The receiving silo is connected to the closed furnace through a discharging pipeline. A discharging control valve for controlling the on-off of the discharging pipeline is provided on the discharging pipeline.

[0017] The gas nozzle is connected to an air supply device, which includes a first air intake pipeline for introducing reaction gas and a second air intake pipeline for introducing replacement gas. The first air intake pipeline is provided with a first air intake control valve for controlling the on-off of the first air intake pipeline, and the second air intake pipeline is provided with a second air intake control valve for controlling the on-off of the second air intake pipeline.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] The fluidized bed vapor deposition furnace of the present invention adopts a closed furnace chamber that is statically arranged, and is provided with a feeding device for feeding materials into the closed furnace chamber, a discharging device for discharging materials from the closed furnace chamber, and an exhaust device for discharging gas from the closed furnace chamber. At the same time, a gas nozzle is arranged at the bottom of the closed furnace chamber, and exhaust is performed in cooperation with the exhaust device. The gas nozzle sprays gas into the furnace chamber to blow the materials upward. On the one hand, the materials will be scattered after being blown upward by the sprayed gas, and some materials will be suspended in the closed furnace chamber, and some materials will fall to the bottom of the closed furnace chamber and be blown upward again by the gas sprayed by the gas nozzle. The materials are repeatedly blown up in the closed furnace chamber to form a boiling effect, so that the materials can be uniformly and fully contacted with the reaction gas to form a uniform coating layer, thereby greatly improving the coating efficiency and coating effect; on the other hand, the sprayed gas forms an impact on the materials, which can blow the materials away, avoid material agglomeration, and can further improve the coating efficiency and coating effect. The fluidized bed vapor deposition furnace does not need to be provided with a precision structure such as a rotating drive device, and has the advantages of simple structure, low cost, easy operation, and convenient maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a structural schematic diagram of a boiling vapor deposition furnace.

[0021] Figure 2 This is a schematic diagram of the structure in which the first spray outlet and the second spray outlet are arranged on the surface of the air nozzle.

[0022] Legend:

[0023] 1. Furnace body; 11. Furnace chamber; 2. Heating device; 3. Feeding device; 31. Positive pressure sending bin; 32. Gas source pipeline; 33. Feeding pipeline; 34. Feeding control valve; 35. Openable and closable feeding port; 4. Discharging device; 41. Receiving bin; 42. Negative pressure blower; 43. Discharging pipeline; 44. Discharging control valve; 5. Exhaust device; 6. Gas nozzle; 601. First air inlet pipeline; 602. Second air inlet pipeline; 603. First air inlet control valve; 604. Second air inlet control valve; 605. First gas supply pipeline; 606. Second gas supply pipeline; 607. First mass flow meter; 608. Second mass flow meter; 609. Mixing tank; 61. First spray port; 62. Second spray port; 7. Feed guide pipe. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1As shown, the boiling vapor deposition furnace of this embodiment includes a furnace body 1 with a closed furnace chamber 11 and a heating device 2 for heating the closed furnace chamber 11, the furnace body 1 is connected with a feeding device 3 for feeding materials into the closed furnace chamber 11, a discharging device 4 for discharging the materials from the closed furnace chamber 11 and an exhaust device 5 for discharging the gas in the closed furnace chamber 11, and a gas nozzle 6 for spraying gas into the furnace chamber 11 to blow the materials upwards is provided at the bottom of the closed furnace chamber 11. The boiling vapor deposition furnace adopts a statically set closed furnace chamber 11, and is provided with a feeding device 3 for feeding materials into the closed furnace chamber 11, a discharging device 4 for discharging materials from the closed furnace chamber 11 and an exhaust device 5 for discharging gases in the closed furnace chamber 11. At the same time, a gas nozzle 6 is provided at the bottom of the closed furnace chamber 11, and exhaust is performed in cooperation with the exhaust device 5. The gas nozzle 6 sprays gas into the furnace chamber 11 to blow the materials upward. On the one hand, the materials will be scattered after being blown upward by the sprayed gas, part of the materials will be suspended in the closed furnace chamber 11, and part of the materials will fall to the bottom of the closed furnace chamber 11 and will be blown upward again by the gas sprayed from the gas nozzle 6. The materials are repeatedly blown up in the closed furnace chamber 11 to form a boiling effect, so that the materials can be evenly and fully contacted with the reaction gas to form a uniform coating layer, thereby greatly improving the coating efficiency and coating effect, with high reaction efficiency and good reaction effect; on the other hand, the sprayed gas has an impact on the materials, which can blow the materials away and avoid material agglomeration, which can further improve the coating efficiency and coating effect. The boiling vapor deposition furnace does not require the installation of precise structures such as a rotating drive device, and has the advantages of simple structure, low cost, easy operation and convenient maintenance.

[0026] In this embodiment, a guide pipe 7 is installed in the closed furnace 11, and an annular material drop space is formed between the guide pipe 7 and the inner wall of the closed furnace 11. The guide pipe 7 has a guide channel that is connected from top to bottom so that the material blown by the gas nozzle 6 can pass through. The lower end of the guide channel is located directly above the gas nozzle 6, and a gap is left between the upper end of the guide channel and the top surface of the furnace 11. The gas ejected from the gas nozzle 6 will carry the material into the guide channel of the guide pipe 7, and the material will rise along the guide channel and diffuse from the upper end of the guide pipe 7 to the surroundings, and then slowly fall from the annular material drop space between the guide pipe 7 and the closed furnace 11, which prolongs the movement path of the material in the closed furnace 11, and also makes the material more evenly distributed in the entire closed furnace 11, and less likely to agglomerate, which can further improve the coating efficiency and coating effect.

[0027] In this embodiment, the material guiding channel is cylindrical, and the cylindrical material guiding channel enables the material to be more evenly diffused to the surroundings from the upper port of the material guiding pipe 7 (that is, the upper opening of the material guiding channel).

[0028] In this embodiment, the surface of the air nozzle 6 is provided with a central area and an annular area surrounding the central area, the central area is provided with more than one first ejection port 61, and the annular area is provided with a plurality of second ejection ports 62, and the airflow velocity ejected from the first ejection port 61 is greater than the airflow velocity ejected from the second ejection port 62. Since the airflow velocity ejected from the first ejection port 61 is greater than the airflow velocity ejected from the second ejection port 62, the airflow ejected from the second ejection port 62 will gather toward the airflow ejected from the first ejection port 61, and then the blown material will gather toward the middle, so that more material passes through the material guide channel of the material guide tube 7, thereby further improving the coating efficiency and coating effect. Preferably, the central area and the annular area are both centered on the center line of the material guide tube 7, so that the material can more easily enter the material guide channel of the material guide tube 7.

[0029] In this embodiment, the air nozzle 6 has an air cavity with an air inlet, all the first ejection ports 61 and all the second ejection ports 62 are connected to the air cavity, and the opening area of ​​the first ejection port 61 is smaller than the opening area of ​​the second ejection port 62. Figure 2 When connected to the same air source, the opening area of ​​the first nozzle 61 is smaller than the opening area of ​​the second nozzle 62, so that the air flow velocity ejected from the first nozzle 61 is greater than the air flow velocity ejected from the second nozzle 62, which not only makes the air nozzle 6 simple in structure, low in cost, and easy to manufacture, but also only requires one air source to supply air to the air nozzle 6, thereby simplifying the air supply device.

[0030] In this embodiment, the communication port between the exhaust device 5 and the closed furnace 11 is located above the upper port of the material guide channel. When the exhaust device 5 is exhausting, the gas in the closed furnace 11 flows upward toward the communication port between the exhaust device 5 and the closed furnace 11, which is not only conducive to the upward movement of the material, but also can slow down the falling speed of the material, so that more material can be suspended, which can further improve the coating efficiency and coating effect. At the same time, after the material flows out from the upper port of the material guide channel, it can be more dispersed and more uniform under the action of the upward airflow, which is also conducive to improving the coating efficiency and coating effect.

[0031] In this embodiment, the air nozzle 6 is located in the middle of the bottom surface of the closed furnace 11, and the bottom surface of the closed furnace 11 is arranged to extend upwardly and obliquely away from the air nozzle 6, that is, the bottom surface of the closed furnace 11 extends from the surroundings in an oblique downward direction to the air nozzle 6. After the material falls, it will slide downward along the bottom surface of the closed furnace 11 and gather above the air nozzle 6, so as to be blown up again. Preferably, the bottom surface of the closed furnace 11 is in an inverted cone shape.

[0032] In this embodiment, the feeding device 3 is a pneumatic feeding device, which includes a positive pressure sending bin 31, which is connected to a gas source pipeline 32 for connecting to a pressure gas source, and the positive pressure sending bin 31 is connected to the closed furnace 11 through a feeding pipeline 33, and a feeding control valve 34 for controlling the on-off of the feeding pipeline 33 is provided on the feeding pipeline 33, and the positive pressure sending bin 31 is also provided with an openable and closable feeding port 35 for feeding. The openable and closable feeding port 35 can be a cover plate connected to the positive pressure sending bin 31 by bolts and sealing the inlet of the positive pressure sending bin 31, or can be an openable and closable valve, etc. After adding the material into the positive pressure sending bin 31 from the openable and closable feeding port 35, the feeding control valve 34 is opened to connect the feeding pipeline 33, and the pressure gas source passes the pressure gas into the positive pressure sending bin 31 through the gas source pipeline 32. The material in the positive pressure sending bin 31 will enter the closed furnace 11 through the feeding pipeline 33 under the conveying effect of the gas, thereby realizing the feeding of the material into the closed furnace 11. After the predetermined amount of material is fed into the closed furnace 11, the feeding control valve 34 is closed to disconnect the feeding pipeline 33 to avoid affecting the subsequent processing. This feeding device 3 has the advantages of simple structure, low cost and simple control.

[0033] In this embodiment, the discharge device 4 includes a receiving silo 41 and a negative pressure blower 42 connected to the receiving silo 41. The receiving silo 41 is connected to the closed furnace 11 through a discharge pipeline 43. The discharge pipeline 43 is provided with a discharge control valve 44 for controlling the on-off of the discharge pipeline 43. When discharge is required, the discharge control valve 44 is opened to connect the discharge pipeline 43, and the negative pressure blower 42 is turned on, so that the material in the closed furnace 11 can enter the receiving silo 41 through the discharge pipeline 43 to realize the discharge of the material. After the discharge is completed, the discharge control valve 44 is closed to disconnect the discharge pipeline 43 to avoid affecting the subsequent processing. The discharge device 4 has the advantages of simple structure, low cost and simple control.

[0034] In this embodiment, the gas nozzle 6 is connected to a gas supply device, which includes a first gas inlet pipeline 601 for introducing reaction gas and a second gas inlet pipeline 602 for introducing replacement gas. The gas supply device includes a first gas inlet control valve 603 for controlling the on-off of the first gas inlet pipeline 601 provided on the first gas inlet pipeline 601, and a second gas inlet control valve 604 for controlling the on-off of the second gas inlet pipeline 602 provided on the second gas inlet pipeline 602. The first gas inlet pipeline 601 can be used to introduce an inert gas (such as nitrogen) for replacement into the closed furnace 11, and the second gas inlet pipeline 602 can be used to supply the reaction gas of the blowing material to the gas nozzle 6. By opening and closing the first gas inlet control valve 603 and the second gas inlet control valve 604, the first gas inlet pipeline 601 and the second gas inlet pipeline 602 can be controlled to work independently without interfering with each other. This gas supply device can supply two different gases to meet the needs of supplying different gases at different stages, and has a simple structure, low cost, and is easy to control.

[0035] In this embodiment, the second air inlet pipeline 602 is also connected to a gas mixing device, which includes a mixing tank 609 connected to the second air inlet pipeline 602, the mixing tank 609 is connected to the first gas supply pipeline 605 and the second gas supply pipeline 606, the first gas supply pipeline 605 is provided with a first mass flow meter 607, and the second gas supply pipeline 606 is provided with a second mass flow meter 608, which can pass two gases (such as hydrocarbon gas and nitrogen) into the mixing tank 609 after proportioning, and then pass to the gas nozzle 6 through the second air inlet pipeline 602. The gas mixing device is provided to facilitate gas supply to the gas nozzle 6.

[0036] In this embodiment, the exhaust device 5 is connected to the closed furnace 11 by a cooler and a dust collector connected to the cooler. The gas exhausted from the closed furnace 11 is cooled by the cooler, and then enters the dust collector for dust removal before being discharged. It works stably and reliably, has a long service life, and can meet environmental protection requirements. The dust collector preferably adopts a sintered plate dust collector with a pulse backflush system. In other embodiments, the exhaust device 5 also refers to the exhaust system used for exhaust in the existing heat treatment kiln.

[0037] In this embodiment, the furnace body 1 and the heating device 2 can be configured with reference to existing heat treatment kilns. Preferably, the furnace body 1 includes a cover shell and a heat-insulating layer arranged in the cover shell, the heat-insulating layer surrounds a closed furnace 11, the cover shell is made of stainless steel material, the heat-insulating layer is made of polycrystalline fiber material, which has good heat-insulating performance and high reflectivity, and the heating device 2 is an alloy resistance wire, which is arranged on the heat-insulating layer.

[0038] When the fluidized bed vapor deposition furnace of this embodiment is used for carbon coating of silicon-carbon negative electrode materials of lithium-ion batteries, the specific steps and working principle are as follows:

[0039] 1. Close the feed control valve 34, the discharge control valve 44, and the second air intake control valve 604, open the first air intake control valve 603, and introduce nitrogen into the closed furnace 11 through the first air intake pipeline 601 to replace the air in the closed furnace 11, so that the nitrogen concentration in the closed furnace 11 reaches 99.99%.

[0040] 2. Close the first air intake control valve 603 , open the second air intake control valve 604 , and introduce a mixed gas of hydrocarbon gas and nitrogen in a preset ratio into the closed furnace 11 through the second air intake pipeline 602 .

[0041] 3. Open the feed control valve 34, and the feed device 3 feeds the lithium-ion battery silicon-carbon negative electrode material into the closed furnace 11. After the material is added, close the feed control valve 34.

[0042] 4. Turn on the heating device 2, then open the second air intake control valve 604, and introduce a mixed gas of hydrocarbon gas and nitrogen in a preset ratio into the closed furnace 11 through the second air intake pipeline 602. The mixed gas is sprayed into the closed furnace 11 through the gas nozzle 6, so that the silicon-carbon negative electrode material of the lithium-ion battery reacts with the mixed gas in the closed furnace 11.

[0043] 5. After the reaction is completed, the mixed gas flow rate is adjusted, the discharge control valve 44 is opened, and the negative pressure blower 42 is turned on to suck the reacted material into the receiving silo 41 to complete the discharge.

[0044] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and changes obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A fluidized bed vapor deposition furnace, characterized in that: The invention comprises a furnace body (1) having a closed furnace chamber (11) and a heating device (2) for heating the closed furnace chamber (11); the furnace body (1) is connected to a feeding device (3) for feeding materials into the closed furnace chamber (11), a discharging device (4) for discharging materials from the closed furnace chamber (11), and an exhaust device (5) for discharging gas from the closed furnace chamber (11); a gas nozzle (6) for injecting gas into the closed furnace chamber (11) to blow the materials upward is provided at the bottom of the closed furnace chamber (11); A material guide pipe (7) is installed in the closed furnace (11), an annular material drop space is formed between the material guide pipe (7) and the inner wall of the closed furnace (11), the material guide pipe (7) has a material guide channel which is connected from top to bottom so that the material blown by the air nozzle (6) can pass through, the lower end of the material guide channel is located directly above the air nozzle (6), and a distance is left between the upper end of the material guide channel and the top surface of the closed furnace (11); the material guide channel is cylindrical; The surface of the air nozzle (6) is provided with a central area and an annular area surrounding the central area, the central area is provided with more than one first ejection outlet (61), the annular area is provided with a plurality of second ejection outlets (62), and the velocity of the air flow ejected from the first ejection outlet (61) is greater than the velocity of the air flow ejected from the second ejection outlet (62).

2. The fluidized bed vapor deposition furnace according to claim 1, characterized in that: The air nozzle (6) has an air cavity with an air inlet, all the first ejection ports (61) and all the second ejection ports (62) are connected to the air cavity, and the opening area of ​​the first ejection ports (61) is smaller than the opening area of ​​the second ejection ports (62).

3. The fluidized bed vapor deposition furnace according to claim 1, characterized in that: The communication port between the exhaust device (5) and the closed furnace (11) is located above the upper port of the material guiding channel.

4. The fluidized bed vapor deposition furnace according to claim 1, characterized in that: The gas nozzle (6) is located in the middle of the bottom surface of the closed furnace (11), and the bottom surface of the closed furnace (11) is arranged to extend upwardly and obliquely in a direction away from the gas nozzle (6).

5. The fluidized bed vapor deposition furnace according to any one of claims 1 to 4, characterized in that: The feeding device (3) is a pneumatic feeding device, comprising a positive pressure sending bin (31), the positive pressure sending bin (31) being connected to a gas source pipeline (32) for connecting to a pressure gas source, the positive pressure sending bin (31) being connected to the closed furnace (11) via a feeding pipeline (33), the feeding pipeline (33) being provided with a feeding control valve (34) for controlling the on-off of the feeding pipeline (33), and the positive pressure sending bin (31) being further provided with an openable and closable feeding port (35) for feeding.

6. The fluidized bed vapor deposition furnace according to any one of claims 1 to 4, characterized in that: The discharge device (4) comprises a receiving bin (41) and a negative pressure blower (42) connected to the receiving bin (41); the receiving bin (41) is connected to the closed furnace (11) via a discharge pipeline (43); and a discharge control valve (44) for controlling the on-off of the discharge pipeline (43) is provided on the discharge pipeline (43).

7. The fluidized bed vapor deposition furnace according to any one of claims 1 to 4, characterized in that: The gas nozzle (6) is connected to a gas supply device, the gas supply device comprising a first gas inlet pipeline (601) for introducing a reaction gas and a second gas inlet pipeline (602) for introducing a replacement gas, the first gas inlet pipeline (601) being provided with a first gas inlet control valve (603) for controlling the on-off of the first gas inlet pipeline (601), and the second gas inlet pipeline (602) being provided with a second gas inlet control valve (604) for controlling the on-off of the second gas inlet pipeline (602).

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