CN106766689B - Microwave material drying device - Google Patents
Microwave material drying device Download PDFInfo
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- CN106766689B CN106766689B CN201710035016.XA CN201710035016A CN106766689B CN 106766689 B CN106766689 B CN 106766689B CN 201710035016 A CN201710035016 A CN 201710035016A CN 106766689 B CN106766689 B CN 106766689B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
- F26B3/34—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects
- F26B3/347—Electromagnetic heating, e.g. induction heating or heating using microwave energy
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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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
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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
- F26B2200/00—Drying processes and machines for solid materials characterised by the specific requirements of the drying good
- F26B2200/06—Grains, e.g. cereals, wheat, rice, corn
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
- Y02P60/80—Food processing, e.g. use of renewable energies or variable speed drives in handling, conveying or stacking
- Y02P60/85—Food storage or conservation, e.g. cooling or drying
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Microbiology (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Biotechnology (AREA)
- Molecular Biology (AREA)
- Drying Of Solid Materials (AREA)
Abstract
The invention relates to a microwave material drying device, which is used for drying a water-containing material at a low temperature based on a microwave technology, wherein a heating device comprises a microwave generator, a microwave heating bin, a tempering bin, a conveying mechanism and ventilation equipment; the microwave heating bin comprises a material container, a feed inlet, a discharge outlet, a microwave antenna and a blade set, wherein an input port of the microwave antenna is connected with a microwave generator, and a radiation port faces towards rice in the container; at least part of the surface of the blade is covered by rice in the container, the direction of the rice flow from the feed inlet to the discharge outlet is taken as the reference direction, and the absolute value of the included angle between the normal direction of the surface of the blade covered by the rice and the reference direction is larger than 0 degree. The invention adopts microwave energy to realize low-temperature drying of rice, has uniform heating, low crushing rate, high energy utilization rate, no pollution discharge, energy conservation and environmental protection.
Description
Technical Field
The invention belongs to the technical field of microwave energy application, and particularly relates to a microwave material drying device.
Background
Drying of rice is the primary link of storage and processing after harvesting. With the continuous improvement of the rice yield in China, the mildew loss caused by untimely drying treatment is increased, so that a great amount of waste is caused, and the problem of high yield and urgent income of agriculture is solved.
The rice belongs to heat-sensitive materials, the temperature of the materials must be strictly controlled (generally not more than 40 ℃) in the drying process, otherwise, the problems of quality reduction and high waist bursting rate are brought. The most widely used rice drying equipment at present adopts a circulating drying process, and the principle block diagram of the circulating drying process is shown in figure 1. The fuel (common coal, biomass, etc.) is burned in the hot blast stove PR1, and the generated heat energy is exchanged to the heat transfer medium-air through the heat exchanger to form hot air; the hot air obtains enough wind pressure under the action of the hot air blower PR2, and then a proper amount of cold air is mixed by the valve PR3 to obtain the required wind temperature. The mixed hot air enters a hot air duct in the heating bin PR4, passes through rice in the heating bin under the action of wind pressure, exchanges heat energy carried by the hot air to rice to be dried, takes away moisture on the surfaces of rice particles, and finally becomes waste gas to be discharged from an air outlet. The rice in the heating bin is discharged into a screw conveyor PR6 under the action of a grain separating mechanism PR5, and is sent to a lifting machine PR7 by the screw conveyor PR 6. The lifting machine PR7 conveys the rice to the tempering warehouse PR8 and enters the tempering process. In the tempering process, water molecules with internal energy obtained migrate from the inside of the rice grains to the surface. Along with the discharge of the rice in the heating bin 4, the rice in the tempering bin PR8 is supplemented to flow into the heating bin, so that a drying process of heating tempering alternate circulation is formed. According to the initial water content of the rice, the times of circulation are different.
Although the above conventional dryer can solve the problems of drying speed, crushing rate, etc., the disadvantages are also apparent.
Firstly, during the heating process, the rice absorbs heat energy from the hot air in a heat conduction mode, and the heat energy is transferred in the rice particles in a conduction mode. Because air and rice are both poor heat conductors, the rice grains are subjected to larger temperature gradient in the heat conduction process, so that the rice grains are easy to crush, the conduction speed is low, the heat transfer time is long, and the heat loss in the heat transfer process is increased, so that the energy consumption is increased. Second, the temperature of the exhaust gas discharged by the hot air heating mode is higher than the temperature of the rice, and the heat energy with a larger proportion is still carried, so that the energy utilization efficiency of the whole machine is further reduced. Finally, the flue gas generated by the combustion of the hot blast stove contains more pollution emission, and serious environmental pollution can be caused by a large amount of use.
The microwave heating has the advantages of high speed and large penetration depth, and has more application in the fields of food, metallurgy, chemical industry, environmental protection and the like. However, in a substantial number of industrial applications, the microwave applicator may be sized to several or even tens of wavelengths, and the microwave field distribution may have a strong non-uniformity, resulting in a spatially non-uniform temperature distribution of the material, which is unsuitable for heating temperature sensitive materials. The microwave is used for rice drying, which has a lot of published research results, but is limited to laboratories and adopts a 2.4GHz household microwave oven as an experimental means, and the results cannot be popularized to actual industrial production, and one main reason is that the uniformity problem of microwave heating cannot be well solved. The rice is used as a temperature sensitive material, the highest temperature is strictly limited in the drying process, if the highest temperature in the whole space is controlled not to exceed the limit, a large amount of distributed rice in a low temperature area cannot obtain enough heat energy, and the heating speed and efficiency are limited, so that the special advantage of microwaves is lost. Up to now, no microwave rice drying device is available for practical industrial production.
Disclosure of Invention
In order to solve the technical problems in the industrial application of material drying in the prior art, the invention provides a microwave material drying device, which can realize high-efficiency, energy-saving and environment-friendly industrial rice drying production by utilizing microwave energy by designing a microwave heating bin and optimizing the structural composition of the whole drying device, and has the following specific scheme:
the microwave material drying device is characterized by comprising a microwave generator, a microwave heating bin, a tempering bin, a conveying mechanism and ventilation equipment; the microwave generator is connected with the microwave heating bin; the conveying mechanism is connected between the tempering bin and the microwave heating bin; the ventilation equipment comprises a fan and an air duct, and the air duct is used for communicating an outlet of the fan with the microwave heating bin and the buffer Su Canglian; the microwave heating bin comprises a material container, a feed inlet and a discharge outlet, wherein materials enter the microwave heating bin from the feed inlet, are filled into the material container, and move from the feed inlet to the discharge outlet under the pushing of the conveying mechanism; the microwave heating bin further comprises a microwave antenna and a blade group, an input port of the microwave antenna is connected with the microwave generator, and a radiation port of the microwave antenna faces the material container; at least part of the surfaces of the blades in the blade group are covered by the materials to be dried in the material container, the direction from the feeding hole to the discharging hole in which the rice flows is taken as a reference direction, and an included angle is formed between the normal direction of the surfaces of the blades covered by the rice and the reference direction.
Preferably, the microwave heating bin further comprises a plurality of independent power distributors, input ports of the power distributors are connected with the microwave generator, the number of output ports of the power distributors is the same as that of the independent microwave antennas, and each output port is connected with one independent microwave antenna.
Preferably, the microwave antenna comprises a rectangular waveguide, a plurality of gaps are formed in the wide side surface of the rectangular waveguide, and an insulating dielectric plate is covered on the gap surface.
Further, a distance is reserved between the wide edge of the rectangular waveguide with the gap and the material.
Further, the microwave antenna further comprises a conical horn, the conical horn is provided with a small-caliber end face and a large-caliber end face, the small-caliber end face is fixedly connected with the wide edge of the rectangular waveguide, which is provided with a gap, so that electric contact is formed, and the large-caliber end face faces the material container.
Preferably, the microwave heating bin comprises a plurality of metal shafts, wherein the metal shafts are positioned in a material container of the microwave heating bin, and the axial direction of the metal shafts is consistent with the flow direction of materials in the material container; blades in the microwave heating bin are arranged on the metal shaft and distributed in a spiral line.
Preferably, the material container is cylindrical, and the axis of the material container is placed in a horizontal direction; the blades are arranged on the inner wall of the material container and are spirally distributed along the axis; the microwave antenna is inserted into the upper space of the material container from one end face of the material container.
Preferably, the microwave heating bin comprises a tunnel-shaped container and a plurality of conveyor belts horizontally arranged in the tunnel-shaped container, and the materials are positioned on the conveyor belts; the microwave antenna is positioned above the conveyor belt; the blade portion is located above the conveyor belt, and the blade portion extends into the material on the conveyor belt.
Preferably, the tempering bin comprises a pipeline in the left-right direction or the front-back direction; the cross section of the pipeline is polygonal, two ends of the pipeline are fixed with the wall of the tempering bin, and small holes are densely distributed on the surface of the pipeline; the pipeline is distributed with a plurality of layers in the height direction of the tempering bin, and if one end of one layer of pipeline is connected with the air duct of the ventilation equipment and the other end is closed, one end of two adjacent layers of pipelines is open to the outside and the other end is closed.
Preferably, the microwave generator is connected with the microwave heating bin through a microwave transmission line.
The invention has the beneficial effects that:
1. the microwave is used as a heat source for industrially drying materials, the advantages of high microwave heating speed and large action depth are fully exerted on the premise of ensuring that the temperature of the rice is not exceeded, and the energy-saving and environment-friendly drying process of the rice which can be used for industrial production is realized.
2. The efficient air supply channel is designed, ventilation air is used for replacing hot air, the temperature gradient between materials and air is reduced, the quality of the dried materials is improved, meanwhile, the emission of hot air is reduced, and the energy is saved.
3. The microwave antenna is used for transmitting microwave energy radiation generated by the microwave generator to rice to be dried, and a group of blades with normal directions not parallel to the flowing direction of the rice are used for generating space position exchange when the rice flows through the surfaces of the blades, so that the problem of uneven heating caused by uneven microwave field distribution in a general microwave applicator is solved.
Drawings
The following describes the embodiments of the present invention in further detail with reference to the drawings;
FIG. 1 is a schematic diagram of a conventional hot air rice dryer;
FIG. 2 is a schematic diagram of the working principle of an embodiment of the present invention;
FIG. 3 (a) is a cross-sectional view of a blade arrangement provided by one embodiment of the present invention;
FIG. 3 (b) is a top view of a blade arrangement provided by one embodiment of the present invention;
FIG. 4 is a schematic diagram of a microwave antenna according to an embodiment of the present invention;
fig. 5 is an enlarged view, partially in section, of a microwave antenna provided in one embodiment of the invention;
FIG. 6 is a schematic diagram of a cross section of a tempering bin wind channel according to an embodiment of the present invention;
FIG. 7 (a) is a side view of a microwave heating cartridge provided in one embodiment of the invention;
FIG. 7 (b) is a schematic cross-sectional view of a microwave heating chamber according to an embodiment of the invention;
FIG. 8 (a) is a side view of a microwave heating cartridge provided in one embodiment of the invention;
fig. 8 (b) is a top view of a microwave heating cartridge provided in one embodiment of the invention.
Reference numerals referred to in the drawings of the specification are explained as follows:
the device comprises a wave generator-1, a microwave heating bin-2, a tempering bin-3, a conveying mechanism-4 and ventilation equipment-5; the device comprises a material container-21, a feed inlet-22, a discharge outlet-23, a microwave antenna-24, blades-25, a shaft-26 and a driving wheel-27; rectangular waveguide-241, cone-shaped horn-242, gap-243, insulating dielectric plate-244; pipeline I-31, pipeline II-32; the grain separating wheel-41, the sloping plate-42 and the lifter-43; the air draft fan-51 and the air duct-52.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
The material in the invention refers to the material to be dried, and specifically, the material can comprise grains such as rice, wheat and the like with certain water content to be dried; nuts such as melon seeds, peanuts, pistachios and pine nuts which need to be dried and stored; dried fruits such as raisin, banana chips and dried mango, feed for drying and transportation, sea-tangle and other marine products for drying; not limited to agricultural byproducts, sand, soil, wood dust and the like which need to remove water also belong to the category of materials in the embodiment; in summary, the present example is not limited to a specific type of material, which is a product or living goods that requires a drying process.
Embodiments of the present invention are described in detail below with reference to the attached drawings, as follows:
the embodiment provides a microwave material drying device, which comprises a microwave generator 1, a microwave heating bin 2, a tempering bin 3, a conveying mechanism 4 and ventilation equipment 5 as shown in fig. 2. The microwave generator 1 is connected with the microwave heating bin, and microwave energy generated by the microwave generator is transmitted into the microwave heating bin; the tempering bin 3 is positioned at the upper part of the microwave heating bin; the conveying mechanism is positioned between the microwave heating bin and the tempering bin and pushes materials to circularly flow; the ventilation equipment 5 forms air flow in the materials to be dried in the microwave heating bin and the tempering bin through the combined action of the fan and the air duct, and takes away moisture on the surfaces of the material particles.
As shown in fig. 2, a microwave heating bin 2 of an embodiment 1 of a microwave material drying apparatus according to the present invention includes a container 21 for holding materials at a lower portion of a bin body, a feed port 22 at one side of the bin body, a discharge port 23 at the opposite side of the feed port, a microwave antenna 24 on the container 21, a set of blades 25, and a shaft 26 for mounting the blades and a driving wheel 27 for driving the shaft 26 to rotate.
Wherein the input port of the microwave antenna 24 is connected with the output end of the microwave generator 1, and the radiation port faces to the materials in the container 21 below; the blades 25 are covered by the material in the container 21.
In one example, the blade 25 is made of a plurality of metal sheets fixed to the surface of the shaft 26, arranged in a spiral (dotted line on the surface of the shaft 26 in fig. 2); one end of the shaft 26 is provided with a driving wheel 27, and the external power machine drives the driving wheel 27 so as to drive the shaft 26 to rotate; the direction of rotation of the shaft 26 ensures that the spiral line in which the blades 25 are arranged is moved from the inlet 22 to the outlet 23.
In one example, as shown in fig. 3 (a), there are three blades in one circumference, with an included angle of 120 ° between the blades, seen in a cross section facing the driving wheel 27. As shown in fig. 3 (b), an included angle is formed between the normal direction 292 of the vane 25 and the axial direction 291 of the shaft 26, in the arrangement mode of the vanes in fig. 3 (b), the driving wheel needs to rotate in the direction shown by the arrow 28, so that the shaft 26 drives the vane 25 to move, and an axial (291) pushing effect is generated on the material, so that the material moves from the feed inlet to the discharge outlet, and meanwhile, the material is stirred to generate radial and tangential movements, thereby realizing the position exchange of the material in three dimensions in the heating bin and overcoming the problem of uneven distribution of microwave fields. In particular, the angle may take different angles, for example 30 °,35 °,40 °,45 °,50 °, etc., which may be chosen between 0 ° (excluding 0 °) and 90 ° depending on the material and on the drying setting. The direction of the rice flow from the feed inlet to the discharge outlet is used as a reference direction, and the absolute value of the included angle between the normal direction of the surface of the rice covered part of the blade and the reference direction is larger than 0 degree.
In one example, the area of the blades 25, the pitch of the helix along which they are distributed, is related to the size of the microwave heating chamber, the thickness of the material in the container 21, and the rotational speed of the shaft 26. Generally, the greater the blade area, the greater the pitch, the faster the material flows in the heating chamber and the shorter the heating time, when the rotational speed is fixed. When the cross section of the microwave heating bin is larger, a plurality of shafts provided with blades can be used in parallel, so that the effect of the blades is ensured to be fully and uniformly.
Preferably, the microwave antenna 24 of the present embodiment adopts a waveguide slot antenna, as shown in fig. 4, and includes a rectangular waveguide 241, where one port 2411 of the rectangular waveguide is an input port of the antenna, and the other port 2412 is short-circuited. The microwave antenna 24 is divided into a plurality of regions along the axis direction of the rectangular waveguide 241, each region has a similar structural form and only has a difference in size so as to ensure that the radiation power value of each region is the same. In this example, the microwave antenna is divided into five areas, denoted as A1 to A5, respectively, and a specific embodiment will be described below with reference to fig. 6 by taking the area A1 as an example. On the broad side of the waveguide in each region, a set of slits 243 are provided, which connect the interior and exterior spaces of the waveguide 241. The position, shape and area of the gap can be simulated according to the required radiation power, and are not taken as technical characteristics of the invention. In this embodiment, the slit is a rectangular slit, and the width of the slit is perpendicular to the axial direction of the waveguide 241. An insulating dielectric plate 244 is covered on the outer surface of the slot 243 to prevent dust and moisture outside the waveguide from entering the waveguide, and reduce the power capacity of the waveguide. As a technical feature of the present invention, a mesa-cone horn 242 is mounted on the slit-opened wide side of the rectangular waveguide, and the small opening surface of the mesa-cone horn is fixed to the waveguide wide side
The electrical contact is defined with the large mouth surface facing the material as the radiation mouth surface. The cone horn 242 has a certain convergence effect on the microwave radiation field of the gap 243, so that the microwave radiation field is concentrated to act on the material below the large opening surface of the cone. The height and the large opening surface size of the conical horn are designed according to the cross section size of the microwave heating bin, so that the field intensity in the material distribution area below the conical horn is ensured to be as uniform as possible. The discoidal horn may be made of, for example, a metallic material.
In one example, the tempering bin 3 of the microwave oven includes a first set of pipes i 31 with polygonal cross sections and a second set of pipes II32 with polygonal cross sections. The shape and the size of the pipeline I31 and the pipeline II32 are the same, and the pipeline I and the pipeline II are placed in parallel; both ends of the pipe I31 and the pipe II32 are respectively fixed to the buffer Su Cangbi. One end of the pipe I31 shown in FIG. 2 is open to the outside space, and the other end is closed; the pipe II32 is closed at the side of the open end of the pipe I31, and is communicated with the air duct 52 at the side of the closed end of the pipe I31, and is further connected with the air draft fan 51. Small holes are densely distributed on the surfaces of the pipeline I31 and the pipeline II 32; the pipes I31 and II32 are staggered in layers, and if the pipe I31 occupies an odd layer, the pipe II32 occupies an even layer, and vice versa. The cross-sectional profiles of the pipe I31 and the pipe II32 are shown in FIG. 6. When the air draft fan 51 works, negative pressure is formed in the air duct 51 and the pipeline 32, and air in the material is pumped out, so that negative pressure is generated in the material; external air enters the material through the small holes on the surface of the pipeline I31 to form air flow so as to take away water vapor on the surface of the material particles.
In one example, as shown in fig. 2, a microwave material drying apparatus is provided, which includes a conveying mechanism, wherein the conveying mechanism includes a grain separating wheel 41, an inclined plate 42 and a lifter 43 below the tempering bin; the grain separating wheel dials the materials in the tempering bin onto the inclined plate 42 through rotation, the inclination angle of the inclined plate 42 and the horizontal plane can be more than 45 degrees, so that the materials flow into the feed inlet 21 of the microwave heating bin under the action of gravity, or the materials can flow into the feed inlet 21 of the microwave heating bin by adopting an inclination angle less than 45 degrees and by means of a conveying belt or a scraper conveying mechanism; the material flowing out of the microwave heating bin discharge port 23 enters a lifting machine 43, and the lifting machine conveys the material to the top of the tempering bin to complete circulation.
In one example, the ventilation device 5 includes an induced draft fan 51, an air duct 52, a blow fan 53, and an air duct 54. Wherein the air draft fan 51 is connected with the tempering bin through an air duct 52; the densely distributed small holes on the surface of the air duct 54 communicate the interior of the air duct with the microwave heating bin, the air blower 53 generates positive pressure in the air duct, and air enters the microwave heating bin through the small holes and passes through the material layer.
In one embodiment, as shown in fig. 7 (a) and 7 (b), the microwave heating cartridge comprises a cylindrical container 71, the two end faces 711 and 722 of which are stationary, and the intermediate portion is rotatable about its own axis. The cylinder 71 axis is placed horizontally or nearly horizontally. The feed port 72 is located on the fixed end face 711; the discharge port is positioned on the fixed end surface 712; the material is contained in the lower space of the container 71. The microwave antenna 74 is inserted into the upper space of the container 71 from the fixed end face 711, and the radiation port faces the material in the lower part of the container. The microwave antenna 74 may also have a fixed end surface 712 that extends into the microwave container 71 in a direction that is not a feature of the present invention. A set of blades 75 made of a plurality of metal sheets are mounted on the inner surface of the container 71 in a standing position, and the blades are arranged in accordance with a spiral line 76 on the inner surface of the container 71, and the important technical feature of the blades is that the angle θ between the surface normal direction and the container axis direction is not zero, i.e. the blade surface normal direction is not parallel to the axis direction. The direction of travel of the spiral 76, along which the blades are aligned as the container 71 rotates, is from the inlet 72 to the outlet 73. The above embodiment ensures that when the container 71 rotates, the blades inside the material will generate axial propelling force to push the material to move from the feed inlet to the discharge outlet, and meanwhile, because the surface normal of the blades is not parallel to the axial direction, radial and tangential propelling forces are generated to drive the material to move radially and tangentially, and meanwhile, the friction force of the inner wall of the cylindrical container can also drive the material to move tangentially, so that the spatial position exchange of the material in three dimensions in the microwave field is finally realized. The specific shape and size of the vane 75 in this embodiment 2 can be designed according to the rotational speed of the container, the material capacity and the drying process, and are not a technical feature of the present invention. In addition, the power mechanical system for driving the container to rotate belongs to the mature technology, and the details of the power mechanical system are not described in the embodiment.
In another embodiment, as shown in fig. 8 (a) and 8 (b), the specific structure of the microwave heating cartridge is different from the previous embodiment. The microwave heating chamber in this embodiment includes a tunnel-type container 81, a conveyor belt 82 is provided at the lower portion of the container 81, a feed inlet 83 is provided at one end of the container 81, and a discharge outlet 84 is provided at the other end. The materials enter the container from the feeding hole 83 and form a pile height with a certain thickness on the conveyor 82; the conveyer belt is driven by the external power mechanical structure to move from the feed inlet to the discharge outlet, so that the material is brought from the feed inlet to the discharge outlet. A microwave antenna 85 is located in the upper space of the container 81 with its radiation opening facing down towards the material on the conveyor belt. The present embodiment also includes a set of blades 86 consisting of a plurality of thin metal sheets; the blades are fixed with the bin wall of the container 81 through connecting rods; the blades are partially or fully embedded in the material on the conveyor belt 82; as shown in fig. 8 (a), the material flow direction flows from the feed inlet (left end face) to the discharge outlet (right end face), i.e. x direction, and the important technical feature of the present invention is that the surface normal direction of each blade forms an angle θ with the material flow direction in the vertical plane (XOZ plane), and θ is not 0; as shown in fig. 8 (b), as an important technical feature of the present invention, the surface normal direction of each blade forms an angle phi with the material flow direction in the horizontal plane (XOY plane), and phi is not 0. Under the condition of the blade installation, when the conveyor belt drives the material to flow, the material moves relative to the surface of the blade, so that the movement direction of the material can be changed by the surface of the blade, and the movement in the Y and Z directions is generated, thereby generating the exchange of the space positions.
In one example, to achieve a sufficient position exchange effect within the vessel, the present embodiment preferably employs a blade arrangement as shown in fig. 8 (b), i.e., the blades 86 are divided into two groups, the normal direction of the first group of blades 861 forming an angle phi with the material flow direction in the XOY plane, and the normal direction of the second group of blades 862 forming an angle-phi with the material flow direction in the XOY plane; in each group of blades, a plurality of blades are fixed on a connecting rod 863 to form a row; the connecting rod 863 is fixed with the bin wall of the container 81; preferably, the first set of blades 861, if arranged in odd columns, the second set of blades 862, if arranged in even columns, and vice versa; preferably, the position of the first set of blades 861 in the Y direction is staggered from the position of the second set of blades 862 in the Y direction.
In one embodiment, a microwave material drying method is provided, and the method uses a microwave material drying device, and specifically comprises the following steps:
step 1, carrying out impurity removal treatment on the materials, and loading the materials into a material drying device through a material conveying device.
In the step 1, the material is subjected to impurity removal treatment by using a mode such as screening or magnetic separation. Taking the material as an example, the screening mode can remove large particles in the material, and the magnetic separation can remove heavy metal impurities in the material. According to the rated power and the volume of the microwave heating bin, the amount of the added material is different, and in one example, the material loading amount in the microwave heating bin is in the range of 6-10 kg/kW, and the material loading amount in the tempering bin is 8-10 times that in the microwave heating bin.
And 2, starting the material conveying device so that after the materials continuously circulate between the microwave heating bin and the tempering bin, starting microwave power, and fully stirring the materials in the microwave heating bin to ensure that the materials are heated uniformly.
In the step 2, the materials in the material conveying device circulate in the microwave heating bin and the tempering bin, are heated in the microwave heating bin, then are gradually cooled in the tempering bin, and moisture is taken away along with air flow, so that the purpose of drying the materials is achieved.
Step 3, measuring the water content of the materials at the grain inlet of the microwave heating bin and the temperature of the materials at the grain outlet of the microwave heating bin in real time; controlling the temperature of the grain outlet of the microwave heating bin in a preset temperature range in real time; if the water content of the materials at the grain inlet of the microwave heating bin is lower than or equal to the standard water content, the following steps are carried out;
if the temperature of the materials heated in the microwave heating bin is too high, the high 'bursting rate' can be caused, and the drying quality of the materials is seriously affected. The temperature in the microwave heating bin can be controlled by controlling the power of the microwaves, and besides the power control, the temperature control can be realized by controlling the time of the materials passing through the microwave heating bin.
Taking the material heated by microwaves as rice, controlling the temperature to be a proper temperature between 38 and 40 ℃, measuring the temperature of a grain outlet of a microwave heating bin, and reducing the microwave heating time if the temperature of the material at the grain outlet of the microwave heating bin exceeds 40 ℃; if the temperature of the materials at the grain outlet of the microwave heating bin is lower than 38 ℃, the microwave heating time is increased. Measuring the water content of the rice while controlling the heating temperature, and continuing the subsequent steps if the water content is less than or equal to the preset water content.
In the step 3, different air supply modes are adopted for the tempering bin and the microwave heating bin, according to the example of taking the material to be dried as rice, an air blower is adopted for the microwave heating bin to ventilate the rice in the microwave heating bin according to the air flow of 2.4m < 3 >/h.kg; and (3) for the tempering bin, an exhaust fan is adopted to exhaust the rice in the tempering bin according to the air flow of 1.8m < 3 >/h.kg. And measuring the water content of the rice at the feeding port of the microwave heating bin in real time, and executing the following steps when the water content is less than or equal to 15%.
And 4, closing microwave power, opening a grain discharging outlet of the microwave material drying device, and keeping the materials in the microwave material drying device to move until the grain discharging is finished.
Table 1 below shows the measurement results of the technical parameters using the method of this example:
table 1 measurement results of technical parameters of microwave drying apparatus
Based on the method, the water content of the rice reaches the drying requirement below 15%, the increase value of the crushing rate is only 0.1%, and the severe crack rate is only 1.8%, so that the rice meets the drying requirement of the rice.
Referring to table 2, table 2 is a comparison table of parameters of the grain drying apparatus of the present invention and the conventional hot air drying apparatus.
Table 2 comparison of grain drying apparatus and Hot air drying Equipment parameters
As shown in Table 2, the grain drying device of the invention utilizes the penetrability heating of microwaves to increase the temperature of the materials, so that the moisture in the materials is vaporized and evaporated, and the vaporized water vapor is discharged by a moisture discharging system to achieve the purpose of drying grains. The microwave drying device has the characteristics of high drying speed, high efficiency, environmental protection, energy conservation, uniform and consistent internal and external heating of grains and the like, and is novel equipment for responding to low carbon economy.
Compared with the existing material drying method, the method has the advantages that the traditional hot air is replaced by the microwave energy, the method is environment-friendly and pollution-free, the heating process is quick, the penetration depth is large, the energy consumption is low, and uniform, quick and high-efficiency heating can be realized by combining full stirring. And on the premise of keeping the microwave power unchanged, the material flow speed is controlled to control the temperature of the heated material, so that the maximum energy production is realized.
It should be understood that references herein to "a plurality" are to two or more. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a exists alone, A and B exist together, and B exists alone. The character "/" generally indicates that the context-dependent object is an "or" relationship.
The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (7)
1. The microwave material drying device is characterized by comprising a microwave generator (1), a microwave heating bin (2), a tempering bin (3), a conveying mechanism and ventilation equipment (5); the microwave generator (1) is connected with the microwave heating bin (2);
the tempering bin (3) comprises a pipeline I (31) and a pipeline II (32) in the left-right direction or the front-back direction; the cross sections of the pipeline I (31) and the pipeline II (32) are polygonal, two ends of the pipeline I (31) and the pipeline II (32) are fixed with the bin wall of the tempering bin (3), and small holes are densely distributed on the surfaces of the pipeline I (31) and the pipeline II (32); the pipeline I (31) and the pipeline II (32) are distributed in a plurality of layers in the height direction of the tempering bin (3), one end of the pipeline II (32) is connected with an air duct of the ventilation equipment, the other end of the pipeline II is closed, the pipeline I (31) is adjacent to the pipeline II (32), the pipeline I (31) is closed at one end of the pipeline II (32) connected with the ventilation equipment, and the pipeline I (31) is open to an external space at one closed end of the pipeline II (32);
the conveying mechanism is connected between the tempering bin (3) and the microwave heating bin (2);
the ventilation equipment (5) comprises an air draft fan (51) and an air duct (52), and the air draft fan is connected with the tempering bin (3) through the air duct; the microwave heating bin (2) comprises a material container (21), a feed inlet (22) and a discharge outlet (23), and the material to be dried enters the microwave heating bin (2) from the feed inlet (22), is filled into the material container (21) and moves from the feed inlet (22) to the discharge outlet (23) under the pushing of the conveying mechanism; the microwave heating bin (2) further comprises a microwave antenna (24) and a blade group, an input port of the microwave antenna (24) is connected with the microwave generator (1), and a radiation port of the microwave antenna (24) faces the material container (21); at least part of the surfaces of the blades (25) in the blade group are covered by the materials in the material container, and the direction from the feeding hole (22) to the discharging hole (23) of the rice flow is taken as a reference direction, and an included angle is formed between the normal direction of the surfaces of the blades covered by the rice and the reference direction; the microwave heating bin (2) comprises a tunnel-shaped container (81) and a plurality of conveyor belts (82) horizontally arranged in the tunnel-shaped container (81), and the materials are positioned on the conveyor belts (82); the blades (25) in the microwave heating bin (2) are divided into two groups, the included angle between the normal direction of the first group of blades (861) and the material flow direction in the XOY plane is phi, and the included angle between the normal direction of the second group of blades (862) and the material flow direction in the XOY plane is-phi; the first set of blades (861) are arranged in odd columns and the second set of blades (862) are arranged in even columns.
2. The apparatus according to claim 1, characterized in that the microwave heating cabinet (2) further comprises a plurality of individual power splitters, the input ports (2411) of which are connected to the microwave generator (1), the number of output ports of which is the same as the number of individual microwave antennas (24), each output port being connected to one individual microwave antenna.
3. The device according to claim 1 or 2, characterized in that the microwave antenna (24) comprises a rectangular waveguide (241) with a plurality of slots (243) open on the broadside surface of the rectangular waveguide, and an insulating dielectric plate (244) is covered on the surface of the slots (243).
4. A device according to claim 3, characterized in that the rectangular waveguide (241) has a gap (243) with a distance from the material.
5. A device according to claim 3, characterized in that the microwave antenna further comprises a conical horn (242), the conical horn (242) having a small-bore end face and a large-bore end face, the small-bore end face being fixedly connected to the slotted (243) broadside of the rectangular waveguide (241) for making electrical contact, the large-bore end face being directed towards the material container (21).
6. The apparatus of claim 1, wherein the microwave antenna (24) is located above the conveyor belt (82); the blade (25) is located above the conveyor belt, the blade (25) extending partially into the material on the conveyor belt (82).
7. The device according to claim 1, characterized in that the microwave generator (1) is connected to the microwave heating chamber (2) by means of a microwave transmission line.
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| CN107281531A (en) * | 2017-06-16 | 2017-10-24 | 西安因变光电科技有限公司 | A kind of high efficiency microwave excitation electrodeless ultraviolet lamp array 1 system |
| CN109900102B (en) * | 2019-04-04 | 2024-01-23 | 湖南郴州粮油机械有限公司 | Sectional drying equipment |
| CN115288798B (en) * | 2022-08-25 | 2023-10-27 | 保银信科信息技术(湖北)有限公司 | Tunnel maintenance intelligent monitoring platform based on sensor acquisition and analysis |
| CN115479450B (en) * | 2022-09-26 | 2023-08-22 | 安徽金锡机械科技有限公司 | Microwave continuous drying system |
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