CN114234614B - Nano powder drying device and method based on electrofluid and ultrasonic technology - Google Patents
Nano powder drying device and method based on electrofluid and ultrasonic technology Download PDFInfo
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- CN114234614B CN114234614B CN202111540946.3A CN202111540946A CN114234614B CN 114234614 B CN114234614 B CN 114234614B CN 202111540946 A CN202111540946 A CN 202111540946A CN 114234614 B CN114234614 B CN 114234614B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
- F26B17/02—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by belts carrying the materials; with movement performed by belts or elements attached to endless belts or chains propelling the materials over stationary surfaces
- F26B17/04—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by belts carrying the materials; with movement performed by belts or elements attached to endless belts or chains propelling the materials over stationary surfaces the belts being all horizontal or slightly inclined
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B23/00—Heating arrangements
- F26B23/04—Heating arrangements using electric heating
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00
- F26B25/001—Handling, e.g. loading or unloading arrangements
- F26B25/002—Handling, e.g. loading or unloading arrangements for bulk goods
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B25/00—Details of general application not covered by group F26B21/00 or F26B23/00
- F26B25/04—Agitating, stirring, or scraping devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B5/00—Drying solid materials or objects by processes not involving the application of heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B5/00—Drying solid materials or objects by processes not involving the application of heat
- F26B5/02—Drying solid materials or objects by processes not involving the application of heat by using ultrasonic vibrations
Abstract
A nanometer powder drying method and device based on electrofluid and ultrasonic technology belongs to the technical field of nanometer powder drying, and comprises a drying chamber, a gas-powder micro-separation device lifting mechanism and a gas-powder micro-separation device fixing mechanism which are positioned at the top of the drying chamber, a plurality of gas-powder micro-separation devices which are positioned inside the drying chamber and fixedly connected with the gas-powder micro-separation device fixing mechanism, and an ultrasonic conveyor belt drying mechanism which is positioned inside the drying chamber and below the gas-powder micro-separation devices, wherein the ultrasonic conveyor belt drying mechanism comprises a conveyor belt and an ultrasonic generator which is positioned below a conveying surface on the conveyor belt, and a ground plate is arranged on the conveying surface of the conveyor belt; the gas-powder micro-separation device comprises a separation cavity with a cyclone structure, a discharge port and a plurality of needle electrodes are arranged at the bottom of the separation cavity, and the needle electrodes are connected with the positive electrode of a high-voltage power supply and are positioned above the conveyor belt.
Description
Technical Field
The invention belongs to the technical field of nano powder drying, and particularly relates to a nano powder drying device and method based on electrofluid and ultrasonic technology.
Background
The nano powder is a micro particle between 1 and 100 nanometers. It has a series of excellent physical, chemical and surface and interface characteristics. In recent years, a large number of novel functional materials are prepared by utilizing nano powder, and various properties of the materials can be obviously enhanced.
The wet chemical synthesis method is a common method for preparing nano powder at present, and the method can lead the nano powder to contain more organic solvent, and meanwhile, the serious agglomeration phenomenon can be formed among the nano powder, so the nano powder needs to be quickly and effectively dried to remove the organic solvent, and the nano powder with good dispersibility is formed. However, in the process of drying the nano powder, along with the temperature change and the evaporation of moisture, chemical reaction is very easy to occur on the surface of the powder slurry to generate bonding aggregates such as oxygen bridges, salt bridges or organic bridges, namely hard aggregates, and the reaction is usually irreversible to form the hard aggregates of the powder, thereby seriously affecting the preparation quality of the nano powder. The higher the drying temperature and the longer the time, the more serious the agglomeration. The structure of the hard aggregate is not easy to be damaged in the application process of the powder, so that the superiority of the nano powder cannot be fully reflected, and the unique function of the nano powder is lost, thereby greatly limiting the application of the nano powder. The agglomeration problem of the nano powder in the drying process seriously troubles the development of powder engineering. Therefore, it is necessary to find a method for suppressing and eliminating powder agglomeration in the drying stage of the nano-powder preparation.
Common methods for drying the nano powder include vacuum freeze drying, microwave drying, hot air drying and the like. The vacuum freeze drying is to separate the adjacent particles by using the expansion force of water in the phase change process, and the formation of solid ice prevents the re-aggregation of the particles, thereby avoiding the generation of hard agglomeration. Microwave drying is to utilize microwave energy to penetrate into the heated object instantly, and the microwave can be converted into heat energy of the substance within a few minutes, thereby reducing the possibility of particle growth and agglomeration, but microwave drying energy consumption is high, and the phenomenon of nonuniform drying of powder due to nonuniform heating field can occur. The hot air drying is a mode of blowing hot air into a drying chamber by using a fan to transfer heat to powder, and drying the powder, but chemical reaction is easy to occur on the surface along with the temperature change and the evaporation of moisture, bonding aggregates such as oxygen bridges, salt bridges or organic bridges are generated, and the agglomeration phenomenon of the powder is aggravated.
Patent CN108557860A discloses a method for preparing inorganic powder by ultrasonic-assisted drying and calcining, which synthesizes a precursor of the inorganic powder in an ultrasonic vibration environment, dries the precursor by resistance heating in the ultrasonic vibration environment, and controls agglomeration of the powder by using cavitation effect of the ultrasonic wave. However, this method requires introduction of ultrasonic waves at multiple stages, and has problems of long powder drying time, extremely low drying efficiency, complicated flow, complicated operation, and the like.
Patent CN107101469A discloses a drying system for nano-powder, which mainly adopts a spray drying system and a hot air system to dry the nano-powder, and collects the dried nano-powder through a separation and collection device. However, the method introduces a hot air system, which causes agglomeration of the powder, and the system has complex design and complex operation flow.
Disclosure of Invention
Aiming at the problems of easy agglomeration of powder, high drying energy consumption, low drying efficiency, discontinuous drying process and the like in the current nano powder drying process, the invention provides a nano powder drying device and method based on electrofluid and ultrasonic technology, and the device and method can realize the continuous drying operation with good nano powder dispersibility, low energy consumption, high efficiency.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
the utility model provides a nanometer powder drying device based on electrofluid and ultrasonic wave technique, includes the drying chamber, is located the gas powder micro-separation device elevating system and the gas powder micro-separation device fixed establishment at drying chamber top, a plurality of gas powder micro-separation device that are located the inside and fixed connection of drying chamber in gas powder micro-separation device fixed establishment and be located the inside and supersound conveyer belt drying mechanism that is located gas powder micro-separation device below of drying chamber.
Specifically, ultrasonic conveyer belt drying mechanism passes through conveyer belt support fixed connection in the bottom of drying chamber, ultrasonic conveyer belt drying mechanism includes the conveyer belt and is located the supersonic generator of conveyer belt top transport face below, and ultrasonic conveyer belt drying mechanism still sets up the adjusting part who is used for driving supersonic generator to carry out the position removal, adjusting part includes the hydraulic stem and the hydraulic stem fixed platform of the vertical setting of ultrasonic drying platform, axis. The conveying belt support is fixedly connected with the hydraulic rod fixing platform, the hydraulic rod is fixedly arranged at the upper end of the hydraulic rod fixing platform, the top of the hydraulic rod is fixedly connected with the ultrasonic drying table, the upper surface of the ultrasonic drying table is provided with a plurality of ultrasonic generators, the distance between the conveying surface of the conveying belt and the ultrasonic generators can be adjusted through the hydraulic rod, and the range of the adjusting distance can reach 50-200mm.
Preferably, the distance between the conveying surface of the conveying belt and the ultrasonic generator is adjusted within the range of 0-50mm, so that the action strength of ultrasonic waves on the nano powder on the conveying belt can be adjusted, the normal operation of the conveying belt can be ensured, the ultrasonic generator does not contact and rub with the conveying belt, and the drying process of the nano powder is ensured.
Preferably, the ultrasonic generator has a frequency in the range of 18kHz-26kHz and can be adjusted in real time.
Preferably, the conveyor belt support is fixedly provided with material baffles on two sides of the conveyor belt, and the material baffles can limit the working interval of drying the nano powder and prevent the nano powder from shaking off the conveyor belt.
Furthermore, the gas-powder micro-separation device comprises a separation cavity of a cyclone structure, a discharge hole is formed in the bottom of the separation cavity, a tangential inlet for enabling mixed powder gas to enter the separation cavity tangentially is formed in one side of the upper portion of the separation cavity, and an air outlet is formed in the top of the separation cavity and extends out of the top of the drying chamber. And mixed powder gas in the drying chamber enters the separation cavity from the tangential inlet, the powder particles rotate at a high speed in the separation cavity, then the powder particles fall along the inside of the separation cavity, the separated nano powder is continuously conveyed onto the conveyor belt from the discharge port for secondary drying, and gas without powder is discharged from the gas outlet.
Preferably, photosensitive resin is selected for the material of separation cavity, adopts 3D printing technology preparation, carries out structure lightweight design to it, alleviates the weight of whole mechanism.
The electrode distribution plate is arranged at the discharge port of the separation cavity, a threaded hole is formed in the middle of the electrode distribution plate, threads are formed in the outer wall of the gas outlet of the separation cavity, and the electrode distribution plate is fixedly connected with the gas outlet of the separation cavity through the threads. The outer wall of the air outlet of the separation cavity is provided with a groove, the groove is used for installing an electrode buckle, and the electrode arrangement plate is electrically connected with the electrode buckle through a high-voltage power supply positive wire. Furthermore, the electrode arrangement board is provided with electrode jacks for inserting the needle electrodes outside the threaded holes, and the needle electrodes are connected with the positive pole of the high-voltage power supply through the electrode arrangement board, the positive lead of the high-voltage power supply and the electrode buckles, so that the needle electrodes obtain high-voltage power supply signals.
Furthermore, the needle electrode is positioned above the conveyor belt, the conveying surface of the conveyor belt is provided with a grounding plate, the grounding plate is grounded, and a high-voltage electric field can be formed between the needle electrode and the conveyor belt, so that the electrofluid drying of the nano-powder on the conveyor belt is realized. Preferably, the high-voltage power supply of the needle electrode adopts 3-10kV high-voltage alternating current and can be adjusted in real time.
Furthermore, the electrode jacks are annularly distributed outside the threaded holes by taking the threaded holes as centers, and the needle electrodes can achieve the maximum efficiency of drying powder. The number of the electrode jacks is even, the number of the pin electrodes is also even, and the number of the pin electrodes can be increased according to the drying requirement.
Furthermore, the drying chamber is provided with an air inlet device, a feeding device and a discharging device.
Specifically, the air inlet device comprises a dry air inlet pipe, the included angle between the central line direction of the dry air inlet pipe and the vertical direction of the drying chamber ranges from 50 degrees to 80 degrees, and a plurality of dry air inlet pipes can be arranged according to the drying requirement. The dry air inlet pipe is provided with a one-way valve which can realize one-way air flow and is used for supplementing a dry air medium required by electrofluid ionization. In the present invention, the moisture content of the dry air medium is less than 0.03%.
Furthermore, the feeding device comprises a powder slurry feeding pipe, a feeding butterfly valve is arranged on the powder slurry feeding pipe, and the feeding butterfly valve can control the blanking speed and the blanking switch of the powder slurry.
Further, discharging device includes hopper, powder finished product discharging pipe, ejection of compact butterfly valve and pneumatic diaphragm pump, the feed end of powder finished product discharging pipe sets up the hopper, set up ejection of compact butterfly valve and pneumatic diaphragm pump on the powder finished product discharging pipe, the ejection of compact butterfly valve is located the upper reaches of pneumatic diaphragm pump, and the ejection of compact butterfly valve is used for the speed of the feeding and the ejection of compact of automatic control nanometer powder, and pneumatic diaphragm pump is used for carrying the inside nanometer powder of powder finished product discharging pipe. The invention automatically controls the speed of feeding and discharging the nano powder by automatically controlling the opening and closing of the discharging butterfly valve of the feeding device and the pneumatic diaphragm pump, and when a certain amount of nano powder is accumulated in the discharging pipe of the finished powder product, the nano powder is conveyed by the pneumatic diaphragm pump.
Furthermore, a discharge port of a powder slurry feeding pipe in the feeding device extends to the upper part of the feeding end of the conveying belt, and is used for uniformly conveying the nano powder slurry to the conveying belt. And the feeding end of a finished powder discharging pipe in the discharging device is positioned below the discharging end of the conveying belt, and after the materials on the conveying belt are completely dried, the materials can be automatically conveyed from the drying chamber through the finished powder discharging pipe according to the required flow velocity.
Preferably, the gas-powder micro-separation device fixing mechanism comprises a gas-powder micro-separation device fixing mechanism and a sliding block, the gas-powder micro-separation device fixing mechanism is fixedly connected with the gas-powder micro-separation device, the gas-powder micro-separation device fixing mechanism is in sliding connection with the gas-powder micro-separation device lifting mechanism in the vertical direction through the sliding block, and the sliding block is used for adjusting the height of the gas-powder micro-separation device fixing mechanism and further adjusting the distance between an electrode needle at the bottom of a separation cavity in the gas-powder micro-separation device and the conveyor belt. According to the invention, the number of the lifting mechanisms of the gas-powder micro-separation device is two, the lifting mechanisms of the gas-powder micro-separation device are symmetrically and fixedly arranged above the drying chamber, and the fixing mechanism of the gas-powder micro-separation device is positioned between the two lifting mechanisms of the gas-powder micro-separation device.
Furthermore, a plurality of clamping rings for clamping the air outlet part of the gas-powder micro-separation device are arranged on the gas-powder micro-separation device fixing mechanism. The position of the clamping ring corresponds to the position of the gas-powder micro-separation device. In the invention, the number of the gas-powder micro-separation devices can be set according to requirements, the arrangement interval between the gas-powder micro-separation devices can be adjusted, and the arrangement interval can be between 20mm and 60 mm. The arrangement intervals among the gas-powder micro-separation devices are determined by controlling the gas-powder micro-separation devices to clamp positions on a gas-powder micro-separation device fixing mechanism.
In the invention, the clamping rings are connected in a ring form through bolts and can be opened, thereby facilitating the adjustment of the position of the gas-powder micro-separation device.
The invention also provides a nano powder drying method based on the nano powder drying device and based on the electrofluid and ultrasonic technology, and the nano powder drying method comprises the following steps:
s1: feeding the synthesized nano powder slurry into a conveyor belt in a drying chamber through a powder slurry feeding pipe in a feeding device, adjusting the feeding flow by controlling a feeding butterfly valve, and simultaneously opening the conveyor belt for conveying movement until the nano powder slurry is uniformly distributed on the upper conveying surface of the conveyor belt;
s2: after the blanking is finished, closing a feeding butterfly valve, stopping conveying of the conveying belt, and moving the ultrasonic generator to the lower edge of the conveying belt by controlling the ultrasonic drying platform to move;
s3: firstly, uniformly spreading nano powder slurry with the water content of 80-90% on the conveyor by using the high-frequency vibration of ultrasonic waves, then repeatedly stretching the nano powder at high frequency by using the high-frequency vibration waves generated by the ultrasonic waves, vibrating water molecules in the nano powder along with the high frequency, and separating the water molecules from the nano powder and flying out when the water molecules are positioned at the wave crest position to achieve the drying effect; meanwhile, the local high temperature, high pressure, strong shock wave, micro jet and the like generated in the ultrasonic cavitation process are utilized to greatly weaken the function energy among the particles, effectively prevent the micro-agglomeration of the nano powder and eliminate the agglomeration phenomenon of the powder;
s4: after the nano powder is subjected to ultrasonic drying, the water content can be reduced to be within the range of 10% -15%, the air inlet device is opened at the moment, high-voltage electricity is applied to the needle electrode, a high-voltage electric field is generated between the needle electrode and the conveyor belt, water molecules in the nano powder are quickly evaporated by utilizing ion wind generated by the high-voltage electric field, the purpose of quick drying is achieved, secondary drying is formed, and the water content of the nano powder is reduced to be below 0.5%; meanwhile, the high-voltage electric field can enable the nano powder to carry the same charge, the nano powder has the phenomenon of like charges repelling each other, and the agglomeration phenomenon is overcome;
meanwhile, mixed powder gas in the drying chamber flows into the separation cavity from the tangential inlet, powder particles rotate at a high speed in the separation cavity and fall along the inner wall of the separation cavity, finally the powder particles fall onto the conveying surface of the conveying belt from the discharge port, and the gas and water gas which do not contain powder escape from the gas outlet;
s5: after the drying of high-voltage electric field is accomplished, the high-voltage electricity of disconnection needle electrode controls the ultrasonic drying platform, makes it remove initial position, waits for the little separator of gas powder to finish the whole separations of nanometer powder in the drying chamber, opens the conveyer belt, and the nanometer powder on the conveyer belt gets into discharging device's hopper in, through pneumatic diaphragm pump, and the nanometer powder after the powder finished product discharging pipe will dry is automatic to be carried away.
Compared with the prior art, the invention has the beneficial effects that:
1. the device and the method for drying the nano powder improve the drying efficiency and save the energy consumption through the combined action of ultrasonic drying and electrofluid drying. The traditional powder drying method has the disadvantages of complex process control, high control cost, complex drying process and long drying time. The invention connects the ultrasonic drying and the electrofluid series drying in series, firstly utilizes the mechanical effect and the cavitation effect of the ultrasonic to quickly reduce the water content of the nano powder, then closes the ultrasonic generator, connects the high voltage electricity of the needle electrode, generates a high voltage electric field between the needle electrode and the grounding plate, and the air and other media near the electrode can be punctured under the high voltage electric field to form ion wind which can quickly evaporate the water in the nano powder and enhance the heat and mass transfer of the nano powder. The electrofluid drying efficiency is high, and drying time is short, can compensate the shortcoming that ultrasonic drying is poor in drying effect under the condition that the water content is lower to can practice thrift the energy consumption, obtain outstanding comprehensive drying effect.
2. The gas-powder micro-separation device is designed in the drying chamber of the nano powder drying device, so that the gas containing moisture in the drying chamber is quickly separated from the nano powder, the effective drying of the nano powder is realized, and meanwhile, the nano powder cannot escape along with airflow. In the electrofluid drying process, but a plurality of gas powder micro-separation device in the drying chamber automatic collection is because the undulant nanometer powder of influence of air current to continue drying on sending to the conveyer belt with it is automatic, can discharge the hydromolecular of evaporation smoothly simultaneously, guarantee drying effect, the function is practical.
3. The nanometer powder drying device is provided with the gas-powder micro-separation device lifting mechanism and the ultrasonic drying platform, and can adjust the distance between the needle electrode and the transmission belt and the distance between the transmission belt and the ultrasonic generator, so that parameters during powder drying can be automatically adjusted and controlled according to different nanometer powders, and the nanometer powder drying device is good in applicability. In addition, the nanometer powder drying device can adjust the drying efficiency in real time by adjusting a plurality of technical parameters such as electrode distance, voltage, the number of electrodes, ultrasonic frequency, dry air flow rate and the like.
4. The device and the method for drying the nano powder utilize the combined action of the ultrasonic wave and the electrofluid, can effectively depolymerize the nano powder, and improve the quality of the dried powder. The nano powder drying device disclosed by the invention utilizes the ultrasonic cavitation effect of ultrasonic drying to generate high temperature and high pressure, so that the evaporation rate of water molecules is increased, and the agglomeration caused by hydrogen bonds can be effectively prevented; in order to ensure that the drying effect is better and prevent the powder from reuniting after the ultrasonic wave stops, the electrofluid is adopted for drying, the particles are charged to the maximum extent with the same charge by a corona charging method, the repulsion is increased to control the reunion, and the powder reuniting phenomenon is avoided probably.
5. The drying chamber of the nano powder drying device is provided with the feeding device and the discharging device, so that continuous and rapid feeding can be realized, continuous and rapid discharging can also be realized after the nano powder is automatically dried, continuous drying operation of the nano powder can be realized, and the efficiency is high.
Drawings
FIG. 1 (a) is a schematic front sectional view of the nano-powder drying apparatus;
FIG. 1 (b) is a schematic side sectional view of the nano-powder drying apparatus;
fig. 2 is a schematic structural diagram of a grounding plate of the nano powder drying device;
FIG. 3 is a sectional view of the gas-powder micro-separation device of the nano-powder drying device;
FIG. 4 is a schematic structural diagram of a clamping ring in the clamping device of the gas-powder micro-separation device of the nano-powder drying device;
fig. 5 is a schematic structural diagram of an electrode arrangement disc of the nano powder drying device.
1 gas-powder micro-separation device lifting mechanism, 2 gas-powder micro-separation device fixing mechanism, 21 gas-powder micro-separation device clamping device, 211 clamping ring, 212 bolts, 22 sliding blocks, 3 drying chamber, 31 air inlet device, 311 one-way valve, 312 dry air inlet pipe, 32 feeding device, 321 feeding butterfly valve, 322 powder slurry feeding pipe, 33 discharging device, 331 hopper, 332 powder finished product discharging pipe, 333 discharging butterfly valve, 334 pneumatic diaphragm pump, 4 ultrasonic conveyor belt drying mechanism, 41 ultrasonic generator, 42 ultrasonic drying platform, 43 hydraulic rod, 44 hydraulic rod fixing platform, 45 material baffle, 46 grounding plate, 47 conveyor belt, 5 needle electrode, 6 electrode arrangement disk, 61 electrode jack, 62 threaded hole, 7 gas-powder micro-separation device, 71 discharging port, 72 tangential inlet, 73 groove, 74 gas outlet, 75 separation cavity, 76 conical thread, 8 electrode buckle and 9 high-voltage power supply positive electrode lead.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples.
Example 1
Referring to fig. 1 (a) and 1 (b), a nano powder drying device based on electrofluid and ultrasonic technology comprises a drying chamber 3, a gas-powder micro-separation device lifting mechanism 1 and a gas-powder micro-separation device fixing mechanism 2 which are positioned at the top of the drying chamber 3, a plurality of gas-powder micro-separation devices 7 which are positioned inside the drying chamber 3 and fixedly connected to the gas-powder micro-separation device fixing mechanism 2, and an ultrasonic conveyor belt drying mechanism 4 which is positioned inside the drying chamber 3 and below the gas-powder micro-separation devices 7.
Wherein, ultrasonic conveyer belt drying mechanism 4 passes through conveyer belt support fixed connection in the bottom of drying chamber 3, ultrasonic conveyer belt drying mechanism 4 includes conveyer belt 47 and is located the supersonic generator 41 of conveyer belt 47 upper run below, and ultrasonic conveyer belt drying mechanism 4 still sets up the adjusting part that is used for driving supersonic generator 41 to carry out position shift, adjusting part includes ultrasonic drying platform 42, the vertical hydraulic stem 43 and the fixed platform 44 of hydraulic stem that sets up of axis. The hydraulic rod fixing platform 44 is fixedly connected with the conveyor belt support, the hydraulic rod 43 is fixedly arranged at the upper end of the hydraulic rod fixing platform 44, the top of the hydraulic rod 43 is fixedly connected with the ultrasonic drying table 42, the upper surface of the ultrasonic drying table 42 is provided with the ultrasonic generators 41, the distance between the conveying surface of the conveyor belt 47 and the ultrasonic generators 41 can be adjusted through the hydraulic rod 43, and the range of the adjusting distance can reach 50-200mm.
In this embodiment, the adjustment range of the distance between the conveying surface of the conveying belt 47 and the ultrasonic generator 41 is 0-50mm, so as to adjust the action intensity of the ultrasonic waves on the nano-powder on the conveying belt 47, ensure the normal operation of the conveying belt 47, prevent the ultrasonic generator 41 from contacting and rubbing the conveying belt 47, and ensure the drying process of the nano-powder.
In the embodiment, the frequency range of the ultrasonic generator is 18kHz-26kHz, and the ultrasonic generator can be adjusted in real time.
In this embodiment, the material baffle 45 is fixedly arranged on the two sides of the conveyor belt 47 of the conveyor belt bracket, and the material baffle 45 can limit the working interval of the drying of the nano-powder and prevent the nano-powder from shaking off from the conveyor belt 47.
Further, referring to fig. 3, the gas-powder micro-separation device 7 includes a separation chamber 75 of a cyclone structure, and the inner diameter of the separation chamber 75 is 3-5mm. The bottom of the separation cavity 75 is provided with a discharge port 71, and one side of the upper part of the separation cavity 75 is provided with a tangential inlet 72 for tangentially introducing mixed powder gas into the separation cavity 75, so as to introduce powder particles involved by the gas flow into the separation cavity 75 of the gas-powder micro-separation device 7. The top of the separation chamber 75 protrudes from the top of the drying chamber 3 and is provided with an air outlet 74. The mixed powder gas in the drying chamber 3 enters the separation cavity 75 from the tangential inlet 72, the powder particles rotate at a high speed in the separation cavity 75, then the powder particles fall down along the inside of the separation cavity 75, the separated nano powder is continuously conveyed to the conveyor belt 47 from the discharge port 71 for secondary drying, and the gas without powder is discharged from the gas outlet 74.
In this embodiment, photosensitive resin is selected for the material of separation cavity 75, adopts 3D printing technology preparation, carries out structure lightweight design to it, alleviates the weight of whole mechanism.
The discharge port 71 of the separation cavity 75 is provided with the electrode distribution plate 6, referring to fig. 5, the middle part of the electrode distribution plate 6 is provided with the threaded hole 62, the outer wall of the gas outlet 74 of the separation cavity 75 is provided with threads, and the electrode distribution plate 6 is fixedly connected with the gas outlet 74 of the separation cavity 75 through the threads. The outer wall of the air outlet 74 of the separation cavity 75 is provided with a groove 73, the groove 73 is used for mounting an electrode buckle 8, and the electrode distribution plate 6 is electrically connected with the electrode buckle 8 through a high-voltage power supply positive electrode lead 9. Further, the electrode arrangement board 6 is provided with a plurality of electrode insertion holes 61 for inserting the pin electrodes 5 outside the threaded holes 61, and the diameter of each electrode insertion hole 61 is 1mm; the needle electrode 5 is connected with the anode of the high-voltage power supply through the electrode arrangement plate 6, the anode lead 9 of the high-voltage power supply and the electrode buckle 8, so that the needle electrode 5 obtains a high-voltage power supply signal, and meanwhile, the needle electrode 5 is prevented from directly penetrating through the internal disturbance flow field of the gas-powder micro-separation device 7.
Further, the needle electrode 5 is located above the conveyor belt 47, referring to fig. 2, a grounding plate 46 is disposed on a conveying surface of the conveyor belt 47, the grounding plate 46 is grounded, and a high-voltage electric field can be formed between the needle electrode 5 and the conveyor belt 47, so that electrofluid drying of the nano-powder on the conveyor belt 47 is realized. Preferably, the high-voltage power supply of the needle electrode adopts 3-10kV high-voltage alternating current and can be adjusted in real time.
Furthermore, the electrode insertion holes 61 are annularly distributed outside the threaded holes 61 by taking the threaded holes 61 as centers, and the needle electrode 5 can achieve the maximum efficiency of drying powder. The number of the electrode insertion holes 61 and the number of the needle electrodes 5 in the present invention are even numbers, and may be added according to the drying requirement.
Further, an air inlet device 31, a feeding device 32 and a discharging device 33 are arranged in the drying chamber 3.
Specifically, the air inlet device 31 includes a dry air inlet pipe 312, an included angle between a center line direction of the dry air inlet pipe 312 and a vertical direction of the drying chamber is 50-80 °, and a plurality of dry air inlet pipes 312 may be arranged according to drying requirements. The dry air inlet pipe 312 is provided with a check valve 311, and the check valve 311 can realize one-way air flow to supplement a dry air medium required by electrofluid ionization. In the present invention, the moisture content of the dry air medium is less than 0.03%.
Further, the feeding device 32 includes a powder slurry feeding pipe 322, a feeding butterfly valve 321 is disposed on the powder slurry feeding pipe 322, and the feeding butterfly valve 321 can control the blanking speed and the blanking switch of the powder slurry.
Further, discharge device 33 includes hopper 331, powder finished product discharging pipe 332, ejection of compact butterfly valve 333 and pneumatic diaphragm pump 334, the feed end of powder finished product discharging pipe 332 sets up hopper 331, set up ejection of compact butterfly valve 333 and pneumatic diaphragm pump 334 on the powder finished product discharging pipe 332, ejection of compact butterfly valve 333 is located the upper reaches of pneumatic diaphragm pump 334, and ejection of compact butterfly valve 333 is used for the feeding of automatic control nanometer powder and the speed of ejection of compact, and pneumatic diaphragm pump 334 is used for carrying the inside nanometer powder of powder finished product discharging pipe 332. The invention automatically controls the speed of feeding and discharging the nano powder by automatically controlling the opening and closing of the discharging butterfly valve 333 and the pneumatic diaphragm pump 334 of the feeding device 33, and when a certain amount of nano powder is accumulated in the powder finished product discharging pipe 332, the nano powder is conveyed by the pneumatic diaphragm pump 334.
Further, the discharge port of the powder slurry feeding pipe 322 in the feeding device 32 extends to the upper side of the feeding end of the conveyor belt 47, so as to uniformly convey the nano powder slurry onto the conveyor belt. The feeding end of the finished powder product discharging pipe 332 in the discharging device 33 is located below the discharging end of the conveyor belt 47, and after all the materials on the conveyor belt 47 are dried, the materials can be automatically conveyed from the drying chamber 3 through the finished powder product discharging pipe 332 according to the required flow rate.
In this embodiment, the gas-powder micro-separation device fixing mechanism 2 includes a gas-powder micro-separation device fixing mechanism 21 and a slider 22, the gas-powder micro-separation device fixing mechanism 21 is fixedly connected with the gas-powder micro-separation device 7, the gas-powder micro-separation device fixing mechanism 21 is connected with the gas-powder micro-separation device lifting mechanism 1 in a sliding manner in the vertical direction through the slider 22, and the slider 22 is used for adjusting the height of the gas-powder micro-separation device fixing mechanism 21, and further adjusting the distance between the electrode needle 5 at the bottom of the separation cavity 75 and the conveyor belt 47 in the gas-powder micro-separation device 7. In this embodiment, the number of the gas-powder micro-separation device lifting mechanisms 1 is two, the gas-powder micro-separation device lifting mechanisms 1 are symmetrically and fixedly installed above the drying chamber 3, and the gas-powder micro-separation device fixing mechanism 21 is located between the two gas-powder micro-separation device lifting mechanisms 1.
Further, the fixing mechanism 21 of the gas-powder micro-separation device is provided with a plurality of clamping rings 211 for clamping the air outlet part of the gas-powder micro-separation device 7. The position of the clamping ring 211 corresponds to the position of the gas powder micro-separation device 7. In the invention, the number of the gas-powder micro-separation devices 7 can be set according to the requirement, the arrangement interval between the gas-powder micro-separation devices 7 can be adjusted, and the arrangement interval can be between 20mm and 60 mm. The arrangement interval between the gas-powder micro-separation devices 7 is determined by controlling the clamping position of the gas-powder micro-separation devices 7 on the gas-powder micro-separation device fixing mechanism 21.
In the present embodiment, referring to fig. 4, the clamping ring 211 is connected in a ring shape by the bolts 212, the diameter of the clamping ring 211 in the present embodiment is 1mm, the clamping force of 34N can be achieved at most by tightening the bolts 212 to fix the clamping ring 211, and thus the outside of the air outlet 74 of the gas-powder micro-separation device 7 with a mass of 0.5kg can be clamped. The clamping ring 211 can be opened to facilitate the adjustment of the position of the gas-powder micro-separation device 7.
Example 2
The present embodiment is a drying method based on the nano powder drying apparatus in embodiment 1, including the following steps:
the method comprises the following steps: before drying, assembling of a nano powder drying device needs to be completed, and specifically the assembling comprises assembling of a gas-powder micro-separation device lifting mechanism 1, a gas-powder micro-separation device fixing mechanism 2, a drying chamber 3, an ultrasonic conveyor belt drying mechanism 4, a needle electrode 5, an electrode arrangement disc 6, a gas-powder micro-separation device 7, an electrode buckle 8 and a high-voltage power supply positive electrode lead 9, and performing air tightness test in the drying chamber 3.
Step two: the synthesized nano powder slurry is fed into the conveyor belt 47 in the drying chamber 3 through the powder slurry feeding pipe 322 in the feeding device 32, the feeding flow rate is adjusted by controlling the feeding butterfly valve 321, and the conveyor belt 47 is opened to carry out conveying movement until the nano powder slurry is uniformly distributed on the upper conveying surface of the conveyor belt 47.
Step three: after the blanking is finished, the feeding butterfly valve 321 is closed, the conveying of the conveying belt 47 is stopped, at this time, the ultrasonic drying platform is controlled to move, the ultrasonic generator 41 is moved to the lower edge of the conveying belt 27, and the ultrasonic drying is started.
Step four: adjusting the frequency of the ultrasonic generator 41 to 26kHz, and uniformly spreading the synthesized nano powder slurry on a conveyor belt 47 by utilizing ultrasonic vibration; after the spreading is finished, the frequency of the ultrasonic generator 41 is adjusted to 22kHz, the nano powder slurry is dried by utilizing the mechanical effect and the cavitation effect of ultrasonic waves, meanwhile, the agglomeration phenomenon of the nano powder is eliminated, and after the ultrasonic drying, the water content of the nano powder can be reduced to be within 10% -15% from 80% -90%.
Step five: the check valve 311 of the dry air inlet device 31 is opened to make the dry air flow into the drying chamber 3 in one direction for supplementing the air medium required for the electro-fluid drying. The high voltage of 8kV is applied to the pin electrode 5, the water in the nano powder is quickly evaporated by utilizing the ionic wind generated by the high voltage electric field, the water content of the nano powder is reduced to be within 0.5 percent, and the high voltage of the pin electrode 5 is cut off at the moment. Meanwhile, the high-voltage electric field generated by the needle electrode 5 is utilized to enable the nano powder to carry the same charge, and the agglomeration phenomenon of the nano powder is overcome due to the physical phenomenon that like charges repel.
Meanwhile, the mixed powder gas in the drying chamber 3 flows into the separation chamber 75 from the tangential inlet 72, the powder particles rotate at a high speed in the separation chamber 75 and fall along the inner wall of the separation chamber 75, and finally fall onto the conveying surface of the conveyor belt 47 from the discharge port 71, and the gas and water gas without powder escape from the gas outlet 74.
Step six: and controlling the hydraulic rod 43 to move the ultrasonic drying platform 42 to the initial position, starting the conveyor belt 47 after the gas-powder micro-separation device 7 completely separates the nano powder, and automatically conveying the dried nano powder out through the discharging device 33 of the drying chamber 3.
The nano powder in the embodiment is silicon powder particles with the average median particle size of 85nm, the ultrasonic generator with the frequency range of 18kHz-26kHz is selected as the ultrasonic generator, the power supply of the electrofluid selects 3-10kV high-voltage alternating current, the nano powder with the water content within 0.5 percent can be obtained through the combined drying of the ultrasonic and the electrofluid, the relative standard deviation is about 10.8 percent, the drying efficiency is high, the drying effect is stable, and the repeatability is good.
The scope of the present invention is not limited to the above embodiments, and any modifications, equivalents, improvements and the like which can be made by those skilled in the art within the spirit and principle of the inventive concept should be included in the scope of the present invention.
Claims (6)
1. A nanometer powder drying device based on electrofluid and ultrasonic technology is characterized by comprising a drying chamber (3), a gas-powder micro-separation device lifting mechanism (1) and a gas-powder micro-separation device fixing mechanism (2) which are positioned at the top of the drying chamber (3), a plurality of gas-powder micro-separation devices (7) which are positioned inside the drying chamber (3) and fixedly connected to the gas-powder micro-separation device fixing mechanism (2), and an ultrasonic conveyor belt drying mechanism (4) which is positioned inside the drying chamber (3) and below the gas-powder micro-separation devices (7);
the ultrasonic conveyor belt drying mechanism (4) comprises a conveyor belt (47) and an ultrasonic generator (41) positioned below a conveying surface on the conveyor belt (47), wherein a grounding plate (46) is arranged on the conveying surface of the conveyor belt (47);
the gas-powder micro-separation device (7) comprises a separation cavity (75) with a cyclone structure, a discharge hole (71) and a plurality of needle electrodes (5) are arranged at the bottom of the separation cavity (75), a tangential inlet (72) for mixed powder gas to enter the separation cavity (75) tangentially is arranged on one side of the upper part of the separation cavity (75), the top of the separation cavity (75) extends out of the top of the drying chamber (3) and is provided with a gas outlet (74), and the needle electrodes (5) are connected with the positive pole of a high-voltage power supply and are positioned above the conveyor belt (47);
the drying chamber (3) is provided with an air inlet device (31), a feeding device (32) and a discharging device (33), a discharging hole of a powder slurry feeding pipe (322) in the feeding device (32) extends to the upper part of the feeding end of the conveyor belt (47), and a feeding end of a powder finished product discharging pipe (332) in the discharging device (33) is positioned below the discharging end of the conveyor belt (47);
the gas-powder micro-separation device fixing mechanism (2) comprises a gas-powder micro-separation device clamping device (21) and a sliding block (22), the gas-powder micro-separation device clamping device (21) is connected with a gas-powder micro-separation device lifting mechanism (1) in a sliding mode in the vertical direction through the sliding block (22), and a plurality of clamping rings (211) used for clamping a separation cavity (75) are arranged on the gas-powder micro-separation device clamping device (21);
the ultrasonic conveyor belt drying mechanism (4) further comprises an ultrasonic drying table (42), a hydraulic rod (43) and a hydraulic rod fixing platform (44), wherein the axes of the hydraulic rod (43) and the hydraulic rod fixing platform are vertically arranged, the hydraulic rod (43) is fixedly arranged at the upper end of the hydraulic rod fixing platform (44), the top of the hydraulic rod (43) is fixedly connected with the ultrasonic drying table (42), and a plurality of ultrasonic generators (41) are arranged on the upper surface of the ultrasonic drying table (42);
a groove (73) for mounting an electrode buckle (8) is formed in the outer wall of an air outlet (74) of the separation cavity (75), an electrode distribution plate (6) is arranged at a discharge hole (71) of the separation cavity (75), and the electrode distribution plate (6) is electrically connected with the electrode buckle (8) through a high-voltage power supply positive wire (9);
the middle part of the electrode arrangement plate (6) is provided with a threaded hole (62) which is used for forming threaded connection with the outside of the discharge hole (71), and the electrode arrangement plate (6) is provided with an electrode jack (61) of the plug-in pin electrode (5) outside the threaded hole (62).
2. The nanopowder drying apparatus of claim 1, wherein material baffles (45) are arranged at two sides of the conveyor belt (47).
3. The nanopowder drying device of claim 1, wherein the electrode insertion holes (61) are annularly distributed outside the threaded holes (62) with the threaded holes (62) as a center, and the number of the electrode insertion holes (61) is even.
4. The nano powder drying device according to claim 1, wherein the air inlet device (31) comprises a dry air inlet pipe (312), an included angle between the direction of the central line of the dry air inlet pipe (312) and the vertical direction of the drying chamber is 50-80 degrees, and a check valve (311) is arranged on the dry air inlet pipe (312).
5. The nanopowder drying device of claim 4, wherein the discharging device (33) comprises a hopper (331), a finished powder product discharging pipe (332), a discharging butterfly valve (333) and a pneumatic diaphragm pump (334), the hopper (331) is arranged at the feeding end of the finished powder product discharging pipe (332), the discharging butterfly valve (333) and the pneumatic diaphragm pump (334) are arranged on the finished powder product discharging pipe (332), and the discharging butterfly valve (333) is positioned at the upstream of the pneumatic diaphragm pump (334).
6. A nano powder drying method based on the nano powder drying device of claim 4 or 5, comprising the steps of:
step A1: the nano powder slurry enters the upper conveying surface of the conveying belt (47) through a powder slurry feeding pipe (322);
step A2: processing the nano powder slurry on the conveying surface of the conveying belt (47) by using an ultrasonic generator (41), wherein the nano powder slurry is uniformly spread by using ultrasonic vibration of ultrasonic waves at first and is dried by using mechanical effect and cavitation effect of the ultrasonic waves at later, and the agglomeration phenomenon of powder is eliminated in the drying process;
step A3: when the water content of the nano powder is reduced to 10-15%, dry air enters the drying chamber (3) through a dry air inlet pipe (312), and the dry air forms ionic wind through a high-voltage electric field generated by the needle electrode (5) to accelerate drying of the nano powder, so that the water content is reduced to be within 0.5%; meanwhile, the high-voltage electric field generated by the needle electrode (5) enables the nano powder to carry the same charge, the physical phenomenon that the nano powder has the same charges and repels each other is generated, and the agglomeration phenomenon of the nano powder is further improved;
meanwhile, mixed powder gas in the drying chamber (3) flows into the separation cavity (75) from the tangential inlet (72), powder particles rotate at a high speed in the separation cavity (75) and fall along the inner wall of the separation cavity (75), finally fall onto a conveying surface on a conveyor belt (47) from a discharge hole (71), and gas and water gas which do not contain powder escape from a gas outlet (74);
step A4: when the nanometer powder is dried by the high-voltage electric field, the gas-powder micro-separation device (7) completely separates the nanometer powder, the conveyor belt (47) brings the nanometer powder to the discharging device (33), and the finished powder discharging pipe (332) automatically conveys the dried nanometer powder out.
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