A method and apparatus for pneumatic dispersion of ultrafine powders

Abstract

This invention provides a pneumatic dispersion method and apparatus for ultrafine powders, relating to the field of powder mechanical dispersion technology. The pneumatic dispersion apparatus comprises a powder silo, nozzles, an expansion pipe, an impact plate, a separation chamber, a powder feeding pipe, and a return gas pipe. High-pressure gas is injected through the nozzles to form a high-speed jet. Ultrafine powder is conveyed into the jet's negative pressure zone via the powder feeding pipe using a dense-phase pneumatic conveying method, forming a high-speed airflow mixing powder and gas. Under the action of airflow shearing and wall collision mechanisms, powder dispersion and agglomeration breakup are achieved. Well-dispersed particles / small agglomerates are carried out with the airflow, while large, unbroken agglomerates undergo secondary separation and return to the nozzle's jet negative pressure zone until complete dispersion. This apparatus has a simple structure, high powder dispersion efficiency, and can obtain a high-concentration, high-dispersion gas-solid two-phase flow of ultrafine powders.

Description

Technical Field

[0001] This invention relates to the field of powder mechanical dispersion technology, and in particular to a pneumatic dispersion method and apparatus for ultrafine powders. Background Technology

[0002] Gas-solid reactions play a very important role in industrial production. Many common industrial products are produced through gas-solid reactions, such as chemical looping combustion of metal oxygen carriers, hydrogen production by iron-steam process, combustion of metal micron particles, and direct nitriding of silicon powder.

[0003] Traditional gas-solid reactions are mainly achieved through fixed-bed and fluidized-bed reactors. Fixed-bed reactors suffer from low gas-solid contact efficiency, reactant agglomeration, and low reaction efficiency, and are difficult to operate continuously. Fluidized-bed reactors offer high gas-solid contact efficiency and high reaction efficiency, but for micro- and nano-sized ultrafine powders, they are prone to agglomeration, forming channels or surges. Therefore, traditional gas-solid fluidized-bed reactors still struggle to achieve efficient continuous gas-solid reactions and industrial applications. Patent CN112794295A and others have proposed a method for achieving continuous gas-solid reactions based on pneumatic conveying, where the powder is conveyed by the gas flow while simultaneously reacting fully with the gas. To ensure production efficiency and reaction rate, the gas flow in the pneumatic conveying gas-solid reaction process must contain a high concentration of powder, and the powder must be in a well-dispersed state.

[0004] Micro- and nano-sized ultrafine particles belong to class C particles. Their small size and large specific surface area make them difficult to exist stably alone, leading to a tendency for them to aggregate. Interparticle forces include liquid bridging forces, van der Waals forces, electrostatic forces, and magnetic forces, which can cause adhesion and aggregation under certain conditions. Researchers are seeking various methods to prevent particle aggregation or to break up agglomerates, enabling ultrafine particles to be fluidized or transported as single particles / small clusters. Commonly used dispersion methods include: particle pretreatment, such as drying, surface coating modification, and mechanochemical surface modification, to eliminate the influence of liquid bridging forces; and the application of mechanical forces, such as vibration, stirring, acoustic fields, and magnetic fields, to counteract the adhesion between microparticles and weaken particle aggregation.

[0005] Mechanical dispersion uses mechanical force to break up particle agglomerates, offering advantages such as high strength and low pollution, making it an effective method for dispersing ultrafine powders. A necessary condition for mechanical dispersion is that the mechanical force must exceed the interparticle adhesion. Utilizing high-speed airflow jets and impact turbulence to break up agglomerates is one of the most effective methods; however, detailed research reports on this topic are relatively rare.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a pneumatic dispersion method and apparatus for ultrafine powders, thereby alleviating the technical problem of easy agglomeration of ultrafine powders in the prior art. Using this method and apparatus, high-concentration, high-dispersion gas-solid two-phase flow of ultrafine powders can be obtained.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, a pneumatic dispersion method for ultrafine powder is provided, wherein high-pressure gas is injected to form a supersonic airflow, the supersonic airflow forms a negative pressure zone, and ultrafine powder is drawn into the negative pressure zone under the negative pressure and mixed with the supersonic airflow, moving at high speed. After mixing and high-speed movement, the supersonic airflow becomes a decelerating airflow, and the ultrafine powder is dispersed through the action of airflow shearing and collision. In this method, the dispersed ultrafine powder is carried out with the decelerating airflow, while the undispersed ultrafine powder is separated and returns to the negative pressure zone to mix with the newly injected supersonic airflow, moving at high speed until it is completely dispersed, ultimately obtaining pneumatically dispersed ultrafine powder.

[0010] Furthermore, the separation method includes one or more of gravity separation and cyclone separation;

[0011] And / or, the ultrafine powder is conveyed to the negative pressure zone by dense-phase pneumatic conveying and mixed with the supersonic airflow, moving at high speed; further, the gas used for dense-phase pneumatic conveying is derived from the dispersion airflow of the supersonic airflow and / or additional supplementary airflow.

[0012] Furthermore, the pressure of the high-pressure gas is 0.1–5 MPa;

[0013] And / or, the speed of the supersonic airflow reaches 500 m / s or more;

[0014] And / or, the negative pressure of the negative pressure zone is 500–2000 Pa;

[0015] And / or, the flow rate of the ultrafine powder in the dense phase pneumatic conveying is 3-30 kg / h;

[0016] And / or, the flow rate of the gas used for dense-phase pneumatic conveying is 1–100 Nm³. 3 / h;

[0017] And / or, the high-pressure gas and the gas used for dense-phase pneumatic conveying are both air or inert gases.

[0018] Furthermore, the ultrafine powder is pre-dried to obtain better dispersion.

[0019] And / or, the high-pressure gas is injected using a Laval nozzle to obtain a supersonic gas flow; further, the high-pressure gas before entering the Laval nozzle is heated or pressurized to obtain a higher jet velocity.

[0020] Secondly, a pneumatic dispersion device for ultrafine powder includes a hopper, a nozzle, an expansion tube, an impact plate, a separation chamber, and a powder feeding pipe. The nozzle, expansion tube, and impact plate are located on the same axis and are arranged sequentially from the bottom to the top of the separation chamber. A gap is left at the connection between the nozzle and the expansion tube for the powder feeding pipe to feed powder. One end of the powder feeding pipe is connected to the connection between the nozzle and the expansion tube, and the other end is connected to the hopper. The expansion tube is provided with a reflux hole for the return of undispersed ultrafine powder for further dispersion.

[0021] Furthermore, the pneumatic dispersion device includes a return air pipe, one end of which is connected to a powder feeding pipe and the other end of which is connected to a separation chamber. When the return air pipe is connected to the separation chamber, it is used to introduce the dispersing airflow in the separation chamber to promote the conveying of ultrafine powder.

[0022] Furthermore, the return air pipe is inclined;

[0023] And / or, the powder feeding pipe is inclined.

[0024] Furthermore, a regulating valve is provided on the separation chamber near one end of the reflux orifice to regulate the opening and closing of the reflux orifice.

[0025] Furthermore, the end of the separation chamber furthest from the nozzle is a cylindrical section, and the end closer to the nozzle is a conical converging section. Even further, the conical converging section has a cone angle of 40 to 80°.

[0026] And / or, the end of the expansion tube near the nozzle is a cylindrical section, and the end away from the nozzle is a tapered expansion section. Furthermore, the cone angle of the tapered expansion section is 15 to 30°.

[0027] Furthermore, the nozzle is a tapered nozzle or a Laval nozzle;

[0028] And / or, the expansion tube and the impact plate are made of heat-resistant and wear-resistant material, and the impact plate is connected to the expansion tube by a heat-resistant and wear-resistant connecting rod;

[0029] And / or, the gas entering the nozzle is a high-pressure gas, and the pressure of the high-pressure gas is 0.1 to 5 MPa;

[0030] And / or, the gas passing through the nozzle is a supersonic gas flow with a velocity of 500 m / s or higher;

[0031] And / or, the gap is an annular negative pressure zone, and the negative pressure of the negative pressure zone is 500 to 2000 Pa;

[0032] And / or, the flow rate of ultrafine powder in the powder feeding pipe is 3-30 kg / h;

[0033] And / or, the flow rate of the gas conveyed in the powder feeding pipe is 1–100 Nm³. 3 / h;

[0034] And / or, the gas entering the nozzle and the conveying gas in the powder delivery pipe are both air or inert gases.

[0035] Furthermore, the separation chamber employs gravity separation and / or cyclone separation to achieve separation;

[0036] And / or, both the powder feeding pipe and the air return pipe are equipped with a vibration motor to facilitate the vibration conveying of powder and prevent blockage;

[0037] And / or, the hopper is equipped with a stirring rod;

[0038] And / or, a vibration motor is installed on the wall surface of the silo and the separation chamber.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] 1. The pneumatic dispersion method for ultrafine powders of the present invention utilizes a supersonic airflow formed by high-pressure gas injection for dispersion, and employs gravity separation and other methods to separate and recirculate undispersed powders for further dispersion by the supersonic airflow until the powders are completely dispersed. Specifically, the supersonic airflow can form a negative pressure zone to promote mixing and high-speed movement of ultrafine powders (which may include powder agglomerates). During the mixing and high-speed movement, the powders and agglomerates are dispersed and broken up under the action of airflow shearing, wall collision, and other mechanisms. The airflow decelerates and carries out well-dispersed powders (which may contain smaller agglomerates broken down from large agglomerates). The powders and agglomerates that do not flow out are separated under gravity and / or other actions and return to the negative pressure zone for secondary pneumatic dispersion. Well-dispersed powders are carried out by the decelerating airflow, and the remaining powders are separated and return to the negative pressure zone for a third pneumatic dispersion. This process is repeated multiple times until all ultrafine powders are dispersed, ultimately obtaining a high-concentration, high-dispersion ultrafine powder gas-solid two-phase flow. After processing ultrafine silicon powder using the method of this invention, a powder-to-air ratio as high as 0.5 kg / m³ can be achieved. 3 High-concentration, highly dispersed airflow.

[0041] 2. In the pneumatic dispersion device for ultrafine powder of the present invention, the nozzle, the expansion tube, and the impact plate are located on the same axis and arranged sequentially from the bottom to the top of the separation chamber. The nozzle orifice is inserted into the expansion tube, and the two form an annular gap around them to form a negative pressure zone for the entry of ultrafine powder. The expansion tube can diffuse the supersonic airflow ejected from the nozzle to avoid impact, while separating the settled and refluxed powder and agglomerates. The impact plate can disperse the powder and prevent the powder from impacting upward and forming agglomerates. In addition, the expansion tube is provided with a return hole, which allows the refluxed powder and agglomerates to enter the negative pressure zone for secondary or even multiple crushing, dispersing and separation, which greatly improves the crushing effect and efficiency of ultrafine powder agglomeration.

[0042] 3. The ultrafine powder pneumatic dispersion device of the present invention can be further provided with a return air pipe connecting the separation chamber and the powder feeding pipe. The dispersion airflow generated by the supersonic airflow is drawn out from the separation chamber through the return air pipe to the powder feeding pipe to promote the conveying of ultrafine powder, reduce the connection with external connections such as the connection of additional airflow used for conveying gas in the powder feeding pipe, increase the overall sealing of the device, and promote the dispersion of ultrafine powder. Furthermore, the separation chamber can be further configured with a cylindrical outlet end and a conical constriction at the inlet end to facilitate the sieving of ultrafine powder that has undergone dispersion and crushing treatment. Furthermore, the expansion pipe can be further configured with a conical expansion at the outlet end and a cylindrical inlet end to facilitate the smooth settling of large particles or agglomerates to the lower part, and facilitate dispersion and circulation through the return hole, etc. Attached Figure Description

[0043] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is the pneumatic dispersion device for ultrafine powder provided in Embodiment 1 of the present invention;

[0045] Figure 2 This is the pneumatic dispersion device for ultrafine powder provided in Embodiment 2 of the present invention.

[0046] Icons: 1-hopper; 2-nozzle; 3-expansion pipe; 4-impact plate; 5-separation chamber; 6-powder feeding pipe; 7-air return pipe; 8-stirring rod; 9-motor; 10-regulating valve; 11-return hole. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0048] In the description of this invention, the terms "opposite," "vertical," "upper," "lower," "parallel," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention. The terms "connected," "linked," and "set up" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a direct connection or an indirect connection through intermediate components; a wired connection, a radio connection, or a wireless communication signal connection. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0049] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0050] According to a first aspect of the present invention, a pneumatic dispersion method for ultrafine powder is provided, wherein a high-pressure gas is injected to form a supersonic airflow, the supersonic airflow forms a negative pressure zone, the ultrafine powder is drawn into the negative pressure zone under the negative pressure and mixes with the supersonic airflow and moves at high speed, the supersonic airflow becomes a decelerating airflow after mixing and high-speed movement, and the ultrafine powder is dispersed by the action mechanism of airflow shearing and collision, wherein the dispersed ultrafine powder is carried out with the decelerating airflow, while the undispersed ultrafine powder is separated and returns to the negative pressure zone to mix with the newly injected supersonic airflow and move at high speed until it is completely dispersed, and finally, pneumatically dispersed ultrafine powder is obtained.

[0051] In this invention, powder with a particle size of less than 10 micrometers is called ultrafine powder. Because ultrafine powder has a small particle size and a large specific surface area, it is easy to form agglomerates / clusters. In the pneumatic dispersion method of this invention, high-pressure gas is injected to form a supersonic airflow. The supersonic airflow can form a negative pressure zone around the side of the injection port. After the negative pressure zone draws in ultrafine powder (which may include powder agglomerates), the ultrafine powder and the supersonic airflow mix and move at high speed. The powder and agglomerates are dispersed and broken up under the action of airflow shearing, wall collision and other mechanisms. The supersonic airflow decelerates and carries out well dispersed powder (which may contain small agglomerates that have been broken down from large agglomerates). The powder and agglomerates that do not flow out are separated under gravity and / or other actions and return to the negative pressure zone for secondary pneumatic dispersion. The well dispersed powder is carried out by the decelerating airflow. The remaining powder is separated and returns to the negative pressure zone for a third time for pneumatic dispersion. This process is repeated many times until all ultrafine powder is dispersed, and finally a high-concentration, high-dispersion ultrafine powder gas-solid two-phase flow is obtained.

[0052] The pneumatic dispersion method of this invention mainly relies on the high velocity gradient of the supersonic airflow itself. By shearing the powder agglomerates through the large gradient velocity difference, the agglomerates are dispersed and broken up. At the same time, the powder agglomerates, especially large agglomerates, will also be impacted under the action of pneumatic force, such as impact with the container wall, or impact with other agglomerates or particles. The impact force overcomes the cohesive force of the powder agglomerates, which can also achieve agglomerate dispersion and breakup.

[0053] The method of this invention can further achieve different dispersion effects and yields by adjusting the pressure, and / or flow rate, and / or injection angle of the high-pressure gas, and / or powder feed concentration, and / or vacuum parameters of the negative pressure zone, specifically achieving a powder-to-gas ratio as high as 0.5 kg / m³. 3 The high-concentration, highly dispersed gas flow. The aforementioned high-pressure gas adjustment parameters can be achieved using existing technologies / devices. For example, by changing the nozzle, the flow rate of the high-pressure gas after injection (also known as the ejector gas flow or high-speed jet) can be adjusted to achieve different powder-carrying gas ratios.

[0054] As an optional embodiment of the pneumatic dispersion method of the present invention, the separation method includes one or more of gravity separation and cyclone separation;

[0055] And / or, the ultrafine powder is conveyed to the negative pressure zone by dense-phase pneumatic conveying and mixed with the supersonic airflow, moving at high speed; further, the gas used for dense-phase pneumatic conveying is derived from the dispersion airflow of the supersonic airflow and / or additional supplementary airflow.

[0056] In the pneumatic dispersion method of this invention, ultrafine powder is fed through dense-phase pneumatic conveying to form a dense-phase gas-solid two-phase flow, thereby promoting the feeding of ultrafine powder and enabling pneumatic dispersion. Because ultrafine powder has a small particle size and a large specific surface area, it is prone to agglomeration during conveying. Therefore, this invention further promotes its flow through dense-phase pneumatic conveying. The flowing dense-phase gas-solid two-phase flow is highly likely to contain ultrafine powder agglomerates, which may be formed before or during the flow process.

[0057] In the pneumatic dispersion method of this invention, high-pressure gas is injected to form a supersonic airflow. The supersonic airflow can form a negative pressure zone around the side of the injection port. After the negative pressure zone draws in the flowing dense phase gas-solid two-phase flow, the ultrafine powder (which may include powder agglomerates) in the dense phase gas-solid two-phase flow moves at high speed during the mixing and merging of the transport gas and the supersonic airflow. The powder and agglomerates are dispersed and broken up under the action of airflow shearing, wall collision and other mechanisms. After the transport gas and supersonic airflow in the dense phase gas-solid two-phase flow merge, they decelerate and carry out well dispersed powder (which may contain small agglomerates that have been broken down from large agglomerates). The powder and agglomerates that do not flow out are separated under gravity and / or other actions and return to the negative pressure zone for secondary pneumatic dispersion. The well dispersed powder is carried out by the decelerating airflow. The remaining powder is separated and returns to the negative pressure zone for a third time for pneumatic dispersion. This process is repeated many times until all ultrafine powder is dispersed, and finally a high-concentration, high-dispersion ultrafine powder gas-solid two-phase flow is obtained.

[0058] As an optional embodiment of the pneumatic dispersion method of the present invention, the pressure of the high-pressure gas is 0.1 to 5 MPa.

[0059] In the above technical solutions, the higher the pressure, the better the spraying effect, but the greater the wear on the equipment, and the higher the overall pressure resistance rating of the equipment also needs to be. Taking all factors into consideration, the pressure of the high-pressure gas is 0.1 to 5 MPa, and typical but non-limiting options include 0.2 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 4.7 MPa, and 4.9 MPa.

[0060] As an optional embodiment of the pneumatic dispersion method of the present invention, the speed of the supersonic airflow reaches 500 m / s or more (such as 501 m / s, 505 m / s, 510 m / s, 530 m / s, 550 m / s, 570 m / s, 590 m / s, 610 m / s, 630 m / s, 650 m / s);

[0061] And / or, the negative pressure of the negative pressure zone is 500 to 2000 Pa (e.g., 550 Pa, 600 Pa, 800 Pa, 1000 Pa, 1200 Pa, 1400 Pa, 1600 Pa, 1800 Pa, 1950 Pa);

[0062] And / or, the flow rate of the ultrafine powder in the dense phase pneumatic conveying is 3 to 30 kg / h (e.g., 4 kg / h, 5 kg / h, 6 kg / h, 7 kg / h, 8 kg / h, 9 kg / h, 10 kg / h, 15 kg / h, 20 kg / h, 25 kg / h, 29 kg / h);

[0063] And / or, the flow rate of the gas used for dense-phase pneumatic conveying is 1–100 Nm³. 3 / h (e.g., 2Nm) 3 / h、3Nm 3 / h、4Nm 3 / h、5Nm 3 / h、6Nm 3 / h、7Nm 3 / h、8Nm 3 / h、9Nm 3 / h, 10Nm 3 / h, 20Nm 3 / h, 30Nm 3 / h, 40Nm 3 / h, 50Nm 3 / h、60Nm 3 / h, 70Nm 3 / h, 80Nm 3 / h、90Nm 3 / h、99Nm 3 / h);

[0064] And / or, the high-pressure gas and the gas used for dense-phase pneumatic conveying are both air or inert gases, typically but not limited to nitrogen and inert gases.

[0065] As an optional embodiment of the pneumatic dispersion method of the present invention, the ultrafine powder is pre-dried to obtain a better dispersion effect;

[0066] And / or, the high-pressure gas is injected using a Laval nozzle to obtain a supersonic gas flow; further, the high-pressure gas entering the Laval nozzle is heated or pressurized to obtain a higher jet velocity.

[0067] In the above technical solutions, to achieve better dispersion and breakup of ultrafine powders and their agglomerations, on the one hand, the ultrafine powders can be pre-dried. The drying temperature will vary depending on the powder, but the moisture content after drying should be controlled to be less than 5%. On the other hand, a Laval nozzle can be used to increase the gas velocity to obtain a supersonic airflow. Furthermore, the higher the pressure and / or temperature of the gas before entering the nozzle, the higher the outlet velocity and the better the dispersion effect. It should be noted that different nozzle outlet sizes correspond to different minimum pressures that can achieve supersonic speeds.

[0068] According to a second aspect of the present invention, a pneumatic dispersion device for ultrafine powder includes a hopper, a nozzle, an expansion tube, an impact plate, a separation chamber, and a powder feeding pipe, wherein the nozzle, expansion tube, and impact plate are located on the same axis and are arranged sequentially from the bottom to the top of the separation chamber; a gap is left at the connection between the nozzle and the expansion tube for the powder feeding pipe to feed powder, one end of the powder feeding pipe is connected to the connection between the nozzle and the expansion tube, and the other end is connected to the hopper; the expansion tube is provided with a reflux hole for undispersed ultrafine powder to be refluxed for further dispersion.

[0069] The pneumatic dispersion device of the present invention can realize the pneumatic dispersion method described in the first aspect.

[0070] As an optional embodiment of the pneumatic dispersion device of the present invention, the device further includes a return air pipe, one end of which is connected to a powder feeding pipe and the other end of which is connected to a separation chamber. When the return air pipe is connected to the separation chamber, it is used to introduce the dispersion airflow in the separation chamber to promote the conveying of ultrafine powder.

[0071] In the pneumatic dispersion device of the present invention, the return gas pipe is used to guide gas from the separation chamber to the powder delivery pipe to promote the flow and conveying of ultrafine powder in the powder delivery pipe. Furthermore, the return gas pipe and / or the powder delivery pipe can be inclined to facilitate the conveying of gas and / or powder.

[0072] The working process of the ultrafine powder pneumatic dispersion device of the present invention includes the following steps:

[0073] S1, load the ultrafine powder into the hopper and close the hopper cover. The ultrafine powder can enter the inclined powder feeding pipe under the action of gravity.

[0074] S2, high-pressure gas is introduced from the bottom of the nozzle and ejected to form a supersonic airflow (Mach number M>1). The supersonic airflow forms a jet negative pressure zone (negative pressure zone) in the gap between the nozzle and the end of the expansion tube near the nozzle.

[0075] S3. Airflow is introduced into the powder feeding pipe. The ultrafine powder is fluidized in the pipe to form a dense phase gas-solid two-phase flow. It flows along the inclined powder feeding pipe by dense phase pneumatic conveying and reaches the powder feeding pipe port. The airflow introduced into the powder feeding pipe can be the airflow introduced into the separation chamber through the return air pipe or an additional supplementary airflow. If the negative pressure generated in the negative pressure zone and the gravity of the ultrafine powder itself are sufficient to maintain the flow of the ultrafine powder in the powder feeding pipe, this step can be omitted, that is, no airflow is introduced into the powder feeding pipe.

[0076] S4, the supersonic airflow draws ultrafine powder and / or dense gas-solid two-phase flow containing ultrafine powder into the ejector negative pressure zone, causing the powder and its agglomerates to move at high speed under the drag of the airflow. The powder agglomerates are broken up by both shearing and collision mechanisms. The supersonic airflow itself has a high velocity gradient, and the large gradient velocity difference shears the powder agglomerates, achieving agglomerate dispersion and breakup. Large agglomerates impact the sides of the expansion tube and the impact plate, and the impact force overcomes the cohesive force of the powder agglomerates, achieving agglomerate dispersion and breakup.

[0077] S5, after the ultrafine powder or dense gas-solid two-phase flow mixed with the supersonic airflow passes through the end of the expansion tube near the impact plate, it is dispersed by the impact plate (the impact plate can prevent the powder from impacting upward and forming agglomerates), and enters the separation chamber. The powder and powder agglomerates are separated by gravity in the separation chamber. The dispersed particles and small agglomerates flow out from the top of the separation chamber with the airflow, while the large agglomerates settle downward and fall back to the bottom.

[0078] S6, the falling powder (unseparated dispersed powder and / or unbroken agglomerates) is ejected by supersonic airflow through the return orifice, repeating S4-S5 until it is completely dispersed and broken up.

[0079] As an optional embodiment of the pneumatic dispersion device of the present invention, an adjusting valve is provided on the separation chamber near one end of the return hole to adjust the opening and closing of the return hole.

[0080] In this invention, the regulating valve is used to adjust the flow area formed between the expansion tube and the separation chamber. The flow area refers to the cross-sectional area of ​​the reflux hole through which gas and / or powder can pass. The regulating valve adjusts the flow area between the expansion tube and the separation chamber, which in effect adjusts the flow area between the negative pressure zone and the reflux zone: when the regulating valve is closed, powder that has not been dispersed after dispersion and / or powder that has not been separated after separation, as well as agglomerates and refluxed ultrafine powder, cannot enter the negative pressure zone and can only deposit in the lower part of the separation chamber (i.e., the reflux zone). The powder that will undergo high-speed dispersion can only come from the powder feeding pipe. When the regulating valve is opened, the ultrafine powder and agglomerates in the reflux zone can enter the negative pressure zone to undergo high-speed movement again, and are then dispersed and broken up, thus performing a normal cycle of crushing and dispersion, separation, crushing and dispersion, and separation. However, at this time, the negative pressure in the negative pressure zone obtained by the powder feeding pipe decreases, and the amount of powder drawn into the negative pressure zone by the powder feeding pipe decreases.

[0081] In addition, during operation, the negative pressure generated by the supersonic airflow ejection can be adjusted by regulating the opening of the regulating valve. When the negative pressure is sufficient, the supplementary airflow into the powder delivery pipe is shut off, and airflow is introduced from the separation chamber through the ejection negative pressure to achieve pneumatic powder conveying in the powder delivery pipe.

[0082] In this invention, the number of regulating valves and reflux orifices is consistent to ensure matching and use, but there are no specific requirements for the number of each; each must be at least one, or multiple, depending on actual needs.

[0083] As an optional embodiment of the pneumatic dispersion device of the present invention, the end of the separation chamber away from the nozzle is a cylindrical structure section, and the end closer to the nozzle is a conical contraction section. Further, the cone surface inclination angle of the conical contraction section is 40-80° (e.g., 41°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 79°).

[0084] In the above technical solution, the separation chamber is configured with a cylindrical outlet and a conical constriction at the inlet to facilitate the sieving of ultrafine powders that have undergone dispersion and crushing. Further research revealed that different conical inclination angles result in different gravity dispersion and reflux effects. Based on the flow characteristics of different ultrafine particles, the conical inclination angle of the conical constriction section is set to 40–80°, which has universal applicability and good sieving and reflux effects for different ultrafine powders.

[0085] In this invention, the cone inclination angle refers to the angle between the cone surface and the longitudinal axis.

[0086] In this invention, the two ends of the separation chamber can be the same or different (e.g., both ends can be cylindrical, or the outlet end can be cylindrical and the inlet end can be conical and constricted). The overall structure of the separation chamber can be integrally formed or segmented and spliced, as long as the overall structure of the separation chamber and the pneumatic dispersion device can form a sealed space.

[0087] As an optional embodiment of the pneumatic dispersion device of the present invention, the end of the expansion tube near the nozzle is a cylindrical structure, and the end away from the nozzle is a conical expansion section. Further, the cone surface inclination angle of the conical expansion section is 15 to 30° (e.g., 16°, 18°, 20°, 22°, 24°, 26°, 28°).

[0088] In the above technical solution, by setting the expansion tube to a conical shape at the outlet end and a cylindrical shape at the inlet end, large particles or agglomerates can be smoothly deposited to the lower part and easily enter the negative pressure zone through the reflux hole. In particular, the conical shape at the outlet end facilitates the upward spraying of diffused airflow and separates the refluxed powder, preventing upward impact and agglomeration. In this invention, more preferably, the end of the expansion tube near the nozzle is configured such that the outer surface can be formed as a cylindrical structure and the inner surface can be formed as a conical structure.

[0089] As an optional embodiment of the pneumatic dispersion device of the present invention, the nozzle is a tapered nozzle or a Laval nozzle.

[0090] In the above technical solution, when high-pressure gas with a pressure of 0.1 to 5 MPa (such as 0.2 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 4.7 MPa, 4.9 MPa) passes through the Laval nozzle, a supersonic airflow (Mach number M>1, velocity reaching 500 m / s or more) can be formed. The supersonic airflow itself has a high velocity gradient, and the large gradient velocity difference shears the powder agglomerates, realizing agglomerate dispersion and breakup. In addition, the supersonic airflow forms an annular negative pressure zone in the gap of the device. The negative pressure of the negative pressure zone is 500-2000 Pa (e.g., 550 Pa, 600 Pa, 800 Pa, 1000 Pa, 1200 Pa, 1400 Pa, 1600 Pa, 1800 Pa, 1950 Pa). The gap includes annular gaps as small as the one between the expansion tube and the nozzle, and annular gaps as large as the one between the hopper and the nozzle. The annular gap (annular gap) between the nozzle and the expansion tube is preferably 1-2 mm (e.g., 1.1 mm, 1.3 mm, 1.5 mm, 1.7 mm, 1.9 mm). It is necessary to avoid an annular gap that is too large, which would result in a low powder flow rate and be unfavorable for dispersion, and also to avoid an annular gap that is too small, which would result in severe wear.

[0091] As an optional embodiment of the pneumatic dispersion device of the present invention, the expansion tube and the impact plate are made of heat-resistant and wear-resistant materials, and the impact plate is connected to the expansion tube by a heat-resistant and wear-resistant connecting rod.

[0092] As an optional embodiment of the pneumatic dispersion device of the present invention, the separation chamber adopts gravity separation and / or cyclone separation to achieve separation;

[0093] And / or, both the powder feeding pipe and the return gas pipe are equipped with vibrating motors to facilitate the vibration conveying of powder and prevent clogging; furthermore, the flow rate of ultrafine powder in the powder feeding pipe is 3-30 kg / h (e.g., 4 kg / h, 5 kg / h, 6 kg / h, 7 kg / h, 8 kg / h, 9 kg / h, 10 kg / h, 15 kg / h, 20 kg / h, 25 kg / h, 29 kg / h), and the gas flow rate is 1-100 Nm³. 3 / h (e.g., 2Nm) 3 / h、3Nm 3 / h、4Nm 3 / h、5Nm 3 / h、6Nm 3 / h、7Nm 3 / h、8Nm 3 / h、9Nm 3 / h, 10Nm 3 / h, 20Nm 3 / h, 30Nm 3 / h, 40Nm 3 / h, 50Nm 3 / h、60Nm 3 / h, 70Nm 3 / h, 80Nm 3 / h、90Nm 3 / h、99Nm 3 / h);

[0094] And / or, the gas entering the nozzle and the conveying gas in the powder delivery pipe are both air or inert gases.

[0095] And / or, the hopper is equipped with a stirring rod, which is driven to rotate by a motor, thereby promoting the ultrafine powder in the hopper to enter the powder feeding pipe;

[0096] And / or, a vibration motor is installed on an optional wall surface of the silo and separation chamber. The installation of the vibration motor causes the ultrafine powder to detach from the wall surface during the conveying process, thereby preventing the ultrafine powder from remaining on the wall surface.

[0097] The present invention will now be described in further detail with reference to specific embodiments and comparative examples.

[0098] Example 1

[0099] A pneumatic dispersion device for ultrafine powders, used for dispersing ultrafine silicon powder and its agglomerates, such as... Figure 1 As shown, the dispersing device includes a hopper 1, a nozzle 2, an expansion pipe 3, an impact plate 4, a separation chamber 5, a powder feeding pipe 6, and a return air pipe 7, wherein...

[0100] The hopper 1 has a diameter of 300mm and a stirring rod 8 is installed in the center. The stirring rod 8 is driven by a motor 9.

[0101] Nozzle 2 is a Laval nozzle with an inner diameter of 24mm, an outlet diameter of 6mm, and a throat diameter of 4mm;

[0102] The lower part of the expansion tube 3 is a straight tube (the lowest end has a certain inner conical surface), with an inner diameter of 10mm and a length of 50mm. The upper part is conical and has an inclination angle of 20° with the axial direction.

[0103] The impact plate 4 is a circular plate with a diameter of 40mm, and is placed at the center of the expansion tube 3;

[0104] The upper part of the separation chamber 5 is a cylindrical cavity with a diameter of 500 mm; the lower part is conical, with an inclination angle of 60-70° with the longitudinal axis, so that the powder settles and flows back through gravity separation.

[0105] The powder feeding pipe 6 is a straight pipe section with an inner diameter of 10mm and an inclination angle of 30-60° with the longitudinal axis.

[0106] The return air pipe 7 is a straight pipe section with an inner diameter of 20mm and an inclination angle of 30-60° with the longitudinal axis.

[0107] A 5mm reflux hole 11 is formed on the side of the expansion tube 3, and a regulating valve 10 is provided on the conical side of the separation chamber 5 to regulate the flow rate through the reflux hole 11.

[0108] The nozzle 2, expansion tube 3, impact plate 4, and separation chamber 5 are installed on the same vertical axis (i.e., longitudinal axis). The nozzle 2 is installed at the bottom of the separation chamber 5 to spray airflow into the separation chamber 5. The expansion tube 3 is installed inside the separation chamber 5 near the upper end of the nozzle 2. The nozzle orifice of the nozzle 2 is inserted into the straight section of the expansion tube 3, forming a 1-2 mm annular slit around it. The expansion tube can diffuse the sprayed airflow to avoid impact and agglomeration, while separating the settled and refluxed powder. The impact plate 4 is located at the upper end of the expansion tube 3 and is connected to the expansion tube 3 through a high-temperature and wear-resistant connecting rod to disperse the powder and prevent the powder from impacting upwards and forming agglomerates. The expansion tube 3 and impact plate 4 are made of high-temperature and wear-resistant material, and the wall surface is coated with a high-temperature and wear-resistant coating.

[0109] The hopper 1 is connected to the outside of the separation chamber 5 via the powder feeding pipe 6 and the air return pipe 7. The outlet of the powder feeding pipe 6 is connected to the annular seam of the nozzle 2 and the expansion pipe 3. One end of the air return pipe 7 is connected to the upper part of the separation chamber 5, i.e., the cylindrical cavity, and the other end is connected to the connection between the powder feeding pipe 6 and the hopper 1, so as to introduce the dispersed airflow in the separation chamber 5 into the powder feeding pipe 6 to promote powder feeding and at the same time promote powder discharge from the hopper 1. The powder feeding pipe 6 and the air return pipe 7 are equipped with a vibration motor (not shown in the figure, this is a non-essential device, but its installation helps the powder flow).

[0110] This embodiment provides the working principle and process of dispersing the ultrafine silica powder agglomerates in a dispersion device, i.e., the dispersion method, including the following steps:

[0111] S1, nozzle 2 is connected to a nitrogen cylinder, and high-pressure nitrogen gas of 1 to 2.5 MPa is introduced. After the high-pressure nitrogen gas is injected through the Laval nozzle, it forms a supersonic airflow with a speed of more than 500 m / s and has high kinetic energy. The supersonic airflow forms a negative pressure zone at the annular gap between nozzle 2 and expansion tube 3.

[0112] S2, change the opening of regulating valve 10 to make the negative pressure in the negative pressure zone about 500~2000Pa;

[0113] S3, put ultrafine silicon powder into the silo 1, turn on the motor 9 of the silo, and after stirring by the stirring rod 8, the silicon powder flow rate of the silo is 3-30 kg / h;

[0114] S4, introduce nitrogen gas into powder feeding pipe 6 at a flow rate of 5 Nm. 3 / h, forming a dense gas-solid two-phase flow of "nitrogen + silicon powder";

[0115] S5, turn on the excitation motor on the powder feeding pipe 6 and the return gas pipe 7 to prevent silicon powder from depositing on the pipe wall;

[0116] S6, silicon powder flows to the outlet of powder feeding pipe 6 under the action of nitrogen gas flow and excitation force;

[0117] S7, the continuously injected supersonic airflow draws in silicon powder. The silicon powder agglomerates are broken and dispersed under the shearing action of the airflow and during the collision with the side wall of the expansion tube 3 and the impact plate 4, forming silicon powder particles and small agglomerates.

[0118] S8, the airflow flows upward along the expander 3 and enters the separation chamber 5, where the velocity decreases;

[0119] S9, the unbroken large agglomerates settle to the bottom of separation chamber 5 under the action of gravity and flow back to the negative pressure zone of the ejector along the conical wall;

[0120] S10, after the silicon powder is ejected, it is dispersed again, that is, the process from S7 to S9 is repeated;

[0121] S11, after the silicon powder is well dispersed, it flows out from the top outlet of separation chamber 5 with the decelerated airflow and enters the subsequent process.

[0122] After the above steps, a powder-to-air ratio as high as 0.5 kg / m³ can be achieved. 3 High-concentration, highly dispersed airflow.

[0123] Example 2

[0124] An ultrafine powder pneumatic dispersion device, such as Figure 2As shown, the device consists of a hopper 1, a nozzle 2, an expansion pipe 3, an impact plate 4, a separation chamber 5, a powder feeding pipe 6, and a return air pipe 7. The main difference from Embodiment 1 is that the upper and lower parts of the separation chamber 5 are both cylindrical structures. Other configurations are the same as or similar to Embodiment 1, as detailed below:

[0125] The hopper 1 is equipped with a stirring rod 8, which is driven by a motor 9.

[0126] The nozzle 2, the expansion tube 3 and the impact plate 4 are located on the same axis and are arranged sequentially from the bottom of the separation chamber 5 upwards.

[0127] A gap is left at the connection between the nozzle 2 and the expansion tube 3 for powder feeding by the powder feeding tube 6;

[0128] The nozzle 2 is a reducing nozzle or a Laval nozzle to obtain supersonic airflow, and the expansion tube 3 and the impact plate 4 are made of heat-resistant and wear-resistant materials.

[0129] The lower part of the expansion tube 3 is a cylindrical structure, and the upper part is a tapered expansion section. The angle between the tapered surface and the axial direction is 15-30°. A reflux hole 11 is opened on the lower side. The size of the reflux hole 11 can be adjusted by the regulating valve 10.

[0130] One end of the powder feeding pipe 6 is located at the connection between the nozzle 2 and the expansion pipe 3, and the other end is connected to the hopper 1 and the return air pipe 7. The other end of the return air pipe 7 is connected to the separation chamber 5.

[0131] The powder feeding pipe 6 and the air return pipe 7 are installed at an angle; a vibrating motor is installed on the powder feeding pipe 6 and the air return pipe 7, and the powder is conveyed by vibration to prevent powder blockage.

[0132] The separation chamber 5 adopts gravity separation, cyclone separation and other forms (the cyclone separation device is not shown in the figure, but is used as an optional device. If selected, an existing cyclone separation device that can achieve separation can be directly installed).

[0133] Vibration motors are installed on the walls of the silo 1 and the separation chamber 5.

[0134] Example 3

[0135] An ultrafine powder pneumatic dispersion device, such as Figure 1 As shown, the device consists of a hopper 1, a nozzle 2, an expansion pipe 3, an impact plate 4, a separation chamber 5, a powder feeding pipe 6, and a return air pipe 7. Similar to Example 1... Figure 1The main difference is that no port for supplementary airflow is provided at the powder feeding pipe 6. That is, the gas used in the dense phase gas-solid two-phase flow in the powder feeding pipe 6 comes entirely from the return gas pipe 7. The dispersed airflow is drawn out from the separation chamber 5 by the ejector negative pressure generated by the supersonic airflow and sent to the powder feeding pipe 6 through the return gas pipe 7 to promote the transport of ultrafine powder. Compared with the device in Example 1, the device in this example has higher sealing performance and is more conducive to efficiently obtaining high-concentration, high-dispersion ultrafine powder gas-solid two-phase flow.

[0136] The working process of the ultrafine powder pneumatic dispersion device, i.e., the ultrafine powder pneumatic dispersion method, includes the following steps:

[0137] S1. The ultrafine powder is pre-dried to obtain better dispersion and crushing effect. Then the ultrafine powder is loaded into the hopper 1 and the hopper cover is closed.

[0138] S2, turn on motor 9 and vibrating motor on hopper, stir rod 8 rotates, ultrafine powder enters powder feeding pipe 6;

[0139] S3, heated high-pressure gas with a pressure of more than 1.0 MPa is introduced from the bottom of nozzle 2 to obtain a higher jet velocity; after the gas passes through the Laval nozzle, a supersonic airflow with a Mach number of M>1 is formed, and the supersonic airflow forms a negative pressure zone at the annular gap between nozzle 2 and expansion tube 3.

[0140] S4, the return pipe 7 is connected to the separation chamber 5 and the powder delivery pipe 6 to form a gas channel, so that the dispersed airflow in the separation chamber 5 is introduced into the powder delivery pipe 6 by negative pressure injection, and the vibration motor on the powder delivery pipe 6 is turned on. The powder vibrates and fluidizes in the pipe, forming a dense phase gas-solid two-phase flow, which flows along the inclined powder delivery pipe and reaches the nozzle injection negative pressure zone.

[0141] S5, the supersonic airflow draws the two-phase flow containing powder into the ejector airflow, and the powder agglomerates obtain high-speed motion under the drag force of the airflow;

[0142] S6, powder agglomerates break up under both shearing and collision mechanisms. The supersonic airflow itself has a high velocity gradient, and the large gradient velocity difference shears the powder agglomerates, thus achieving agglomerate dispersion and breakup.

[0143] Large agglomerates impact the sides of the expansion tube 3 and the impact plate 4. The impact force overcomes the cohesive force of the powder agglomerates, thus achieving agglomerate dispersion and breakage.

[0144] S7, the airflow decelerates after passing through the conical expander 3 and enters the separation chamber 5;

[0145] S8, powder and powder agglomerates undergo gravity separation in separation chamber 5. Dispersed particles and small agglomerates flow out from the top of separation chamber 5 with the airflow, while large agglomerates settle downwards and fall back to the bottom along the lower conical section of separation chamber 5.

[0146] S9, the falling powder is guided by the airflow and repeats S5-S8 until it is completely dispersed and broken.

[0147] During operation, the negative pressure generated by the ejector can be adjusted by regulating the opening of valve 10. When the negative pressure is sufficient, the ejector negative pressure introduces airflow from the separation chamber 5 to achieve powder conveying in the powder delivery pipe 6.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pneumatic dispersion device for ultrafine powders, characterized in that: The ultrafine powder is a powder with a particle size of less than 10 micrometers. The device includes a hopper (1), a nozzle (2), an expansion tube (3), an impact plate (4), a separation chamber (5), and a powder feeding pipe (6). The nozzle (2), expansion tube (3), and impact plate (4) are located on the same axis and are arranged sequentially from the bottom to the top of the separation chamber (5). A gap is left at the connection between the nozzle (2) and the expansion tube (3) for the powder feeding pipe (6) to feed powder. The annular gap between the nozzle (2) and the expansion tube (3) is 1-2 mm. One end of the powder feeding pipe (6) is connected to the connection between the nozzle (2) and the expansion tube (3), and the other end is connected to the hopper (1). The expansion tube (3) is provided with a return hole (11) for the return of undispersed ultrafine powder for further dispersion. A regulating valve (10) is provided on the separation chamber (5) near one end of the reflux hole (11) to regulate the opening and closing of the reflux hole (11).

2. The pneumatic dispersion device as described in claim 1, characterized in that: Includes a return air pipe (7), one end of which is connected to a powder feeding pipe (6) and the other end is connected to a separation chamber (5). When the return air pipe (7) is connected to the separation chamber (5), it is used to introduce the dispersed airflow in the separation chamber (5) to promote the conveying of ultrafine powder. The return air pipe (7) is inclined. And / or, the powder feeding pipe (6) is inclined.

3. The pneumatic dispersion device as described in claim 1, characterized in that: The separation chamber (5) is a cylindrical section at the end away from the nozzle (2) and a conical constriction section at the end near the nozzle (2). The conical constriction section has a cone inclination angle of 40~80°. And / or, the end of the expansion tube (3) near the nozzle (2) is a cylindrical structure section, and the end away from the nozzle (2) is a conical expansion section, and the conical surface inclination angle of the conical expansion section is 15~30°.

4. The pneumatic dispersion device according to claim 1, characterized in that: The nozzle (2) is a tapered nozzle or a Laval nozzle; And / or, the expansion tube (3) and the impact plate (4) are made of heat-resistant and wear-resistant materials, and the impact plate (4) is connected to the expansion tube (3) by a heat-resistant and wear-resistant connecting rod; And / or, the gas entering the nozzle is a high-pressure gas, and the pressure of the high-pressure gas is 0.1~5MPa; And / or, the gas passing through the nozzle is a supersonic gas flow with a velocity of 500 m / s or higher; And / or, the gap is an annular negative pressure zone, and the negative pressure of the negative pressure zone is 500~2000 Pa; And / or, the flow rate of ultrafine powder in the powder feeding pipe (6) is 3~30 kg / h; And / or, the flow rate of the gas conveyed in the powder feeding pipe (6) is 1~100 Nm. 3 / h; And / or, the gas entering the nozzle and the conveying gas in the powder delivery pipe (6) are both air or inert gas.

5. The pneumatic dispersion device according to claim 1, characterized in that: The separation chamber (5) achieves separation by gravity separation and / or cyclone separation. And / or, both the powder feeding pipe (6) and the air return pipe (7) are equipped with a vibration motor to facilitate the vibration conveying of powder and prevent blockage; And / or, the hopper (1) is equipped with a stirring rod (8); And / or, a vibration motor is installed on the wall surface of the silo (1) and the separation chamber (5).

6. A method for pneumatic dispersion of ultrafine powder, characterized in that: Using the pneumatic dispersion device for ultrafine powder as described in claim 1, high-pressure gas is injected to form a supersonic airflow. The supersonic airflow forms a negative pressure zone. Under the negative pressure of the negative pressure zone, the ultrafine powder is drawn into the negative pressure zone and mixed with the supersonic airflow, moving at high speed. After mixing and high-speed movement, the supersonic airflow becomes a decelerating airflow. The ultrafine powder is dispersed through the shearing and collision mechanism of the airflow. The dispersed ultrafine powder is carried out with the decelerating airflow, while the undispersed ultrafine powder is separated and returns to the negative pressure zone to mix with the newly injected supersonic airflow, moving at high speed until it is completely dispersed, ultimately obtaining pneumatically dispersed ultrafine powder.

7. The pneumatic dispersion method according to claim 6, characterized in that: The separation method includes one or more of gravity separation and cyclone separation; And / or, the ultrafine powder is conveyed to the negative pressure zone by dense-phase pneumatic conveying and mixed with the supersonic airflow, moving at high speed; the gas used for dense-phase pneumatic conveying is derived from the dispersion airflow of the supersonic airflow and / or additional supplementary airflow.

8. The pneumatic dispersion method according to claim 7, characterized in that: The pressure of the high-pressure gas is 0.1~5MPa; And / or, the speed of the supersonic airflow reaches 500 m / s or more; And / or, the negative pressure of the negative pressure zone is 500~2000 Pa; And / or, the flow rate of the ultrafine powder in the dense phase pneumatic conveying is 3~30 kg / h; And / or, the flow rate of the gas used for dense-phase pneumatic conveying is 1~100 Nm³. 3 / h; And / or, the high-pressure gas and the gas used for dense-phase pneumatic conveying are both air or inert gases.

9. The pneumatic dispersion method according to claim 6, characterized in that: The ultrafine powder is pre-dried to obtain better dispersion. And / or, using a Laval nozzle to inject the high-pressure gas to obtain a supersonic gas flow; heating or pressurizing the high-pressure gas before it enters the Laval nozzle to obtain a higher jet velocity.

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