JP5831413B2 - Microwave drying apparatus and microwave drying method - Google Patents

Description

  The present invention relates to a microwave drying apparatus and a microwave drying method.

  As the production of steel materials by electric furnaces becomes popular, the demand for scrap, which is the main raw material, is tightened, and the demand for reduced iron is increasing due to the demand for high-grade steel production in electric furnaces.

  As one of the methods for producing reduced iron, iron oxide raw materials such as powdered iron ore and iron-making dust are mixed with carbonaceous materials such as powdered coal and coke, for example, a lump such as pellets and briquettes. There is a method in which an agglomerated material is obtained, and this agglomerated material is charged into a reduction furnace such as a rotary hearth furnace and heated to a high temperature to reduce the iron oxide raw material to obtain solid metallic iron. In such a method, it is important to adjust the moisture content of the agglomerated material containing the iron oxide raw material and the carbonaceous material in order to increase the reduction rate of the agglomerated material.

  In the manufacturing process of reduced iron as described above, as a device for adjusting the moisture content of agglomerates, etc., a tunnel-shaped furnace for drying the material to be dried placed on a wire mesh conveyor by hot air (For example, refer to Patent Document 1 below.) Such a drying furnace dries the material to be dried by passing hot air from the top to the bottom of the furnace.

  Since the drying furnace as disclosed in Patent Document 1 is hot air drying by supplying hot air upward, the lower layer portion of the raw material to be dried (portion close to the wire mesh conveyor) Drying is delayed, and drying of the small block raw material located in the lower layer portion becomes insufficient. If the drying of the small block material is insufficient, the strength of the small block material is insufficient, and in the next step, the small block material is pulverized, resulting in a reduction in production yield. In addition, in order to prevent such a reduction in production yield, it is necessary to add various binders to be mixed with the small mass raw material, resulting in an increase in manufacturing cost.

  In addition, since the small lump material contains carbonaceous materials such as coal and coke, if the small lump material is heated too much, there is a risk of ignition, and it is difficult to improve the drying efficiency by raising the temperature of the hot air. is there. Therefore, from the viewpoint of preventing ignition, it is required to selectively heat the lower layer portion where moisture remains rather than the upper layer portion that is sufficiently dried.

  In addition to the drying furnace using hot air as described above, there has been proposed a drying furnace that irradiates microwaves into the free space of the drying chamber from the outside of the workpiece in order to assist drying by the heater ( For example, see the following Patent Document 2.)

JP-A-2005-113197 JP-A-6-347165

  In the manufacturing process of reduced iron as described above, the layer thickness of the agglomerated material to be dried in the drying furnace is as thick as about 200 mm or more. Therefore, as described in Patent Document 2, when microwaves are applied to the free space in the furnace, it is possible to cause the microwaves to act on the upper layer portion of the agglomerate layer. As will be described in detail, as a result of investigations by the present inventors, it has become clear that microwaves cannot be applied to the lower layer portion of the agglomerated material.

  In addition, since the conveyor for transporting the heavy agglomerate is a metal wire mesh, even if microwaves are irradiated from the back surface of the conveyor to the lower part of the agglomerate, the microwave is transmitted by the metal conveyor. Is reflected, and microwaves cannot be applied to the lower layer portion of the agglomerated material.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to selectively select a lower layer portion of an object to be dried charged in a drying furnace using a microwave. An object of the present invention is to provide a microwave drying apparatus and a microwave drying method that can be heated.

In order to solve the above-described problem, according to a certain aspect of the present invention, when the object to be dried is transported by a conveyor, moisture contained in the object to be dried is reduced by blowing hot air against the object to be dried. A microwave drying apparatus installed in a hot-air drying furnace, comprising: a microwave oscillator that oscillates a microwave used for drying the object to be dried; and the object to be dried being conveyed. A heating range in which the object to be dried is heated by the microwave is inserted to a depth including the lowermost layer of the object to be dried, and the microwave is applied to the object to be dried. A plurality of waveguides to be irradiated and a plurality of openings provided on the upper surface of the waveguide that guides the microwaves provided directly above the conveyor, and from the plurality of openings to the object to be dried On the other hand, Includes a plurality of slits antenna for irradiating the black waves, and, before Kishirubeha tubes each of the heating range, and such that the opening of the slit antenna to cover the furnace entire width direction of the drying furnace as a whole A microwave drying apparatus is provided that is arranged at a regular interval .

Moreover, in order to solve the said subject, according to another viewpoint of this invention, when conveying a to-be-dried object with a conveyor, the moisture contained in the to-be-dried object by spraying a hot air with respect to the to-be-dried object A microwave drying apparatus installed in a hot-air drying furnace for reducing the temperature, a microwave oscillator for oscillating a microwave used for drying the object to be dried, and the object to be dried being conveyed A heating range in which the object to be dried is heated by the microwave is inserted to a depth including the lowermost layer of the object to be dried, with respect to the object to be dried. A plurality of coaxial antennas for irradiating microwaves and a plurality of openings on an upper surface of a waveguide that is provided directly above the conveyor and that guides the microwaves. To things And a plurality of slits antennas irradiating the microwave to the heating range of each of the coaxial antenna, and the opening of the slit antenna to cover the furnace entire width direction of the drying furnace as a whole A microwave drying apparatus arranged at such intervals is provided.

  At least two of the plurality of waveguides or coaxial antennas are arranged at different positions in the furnace width direction of the drying furnace, and the waveguides or coaxial antennas adjacent to each other in the furnace width direction are arranged. The positions in the transport direction are preferably different from each other.

Wherein the plurality of waveguides, the end portion facing the front Kiko conveyors the waveguide when inserted into the material to be dried layer may be an opening.

  The plurality of waveguides are formed on the layer to be dried so that a separation distance between a front end portion of the waveguide and the conveyor is equal to or more than a quarter of a wavelength of the microwave in free space. It is preferably inserted.

  The plurality of waveguides are provided with a notch on at least a side surface that is parallel to the drying object layer transport direction of the drying furnace when the waveguide is inserted into the drying object layer. The microwave may be irradiated from the notch.

  The plurality of waveguides are preferably inserted into the material to be dried such that an upper end in the height direction of the material layer to be dried is not more than a height of the material layer to be dried. .

  In the plurality of waveguides, a distance between an upper end in a height direction of the layer to be dried of the notch and the conveyor is equal to or more than a quarter of the wavelength of the microwave in free space. It is preferable to be inserted into the dried material layer.

  The slit antenna may be arranged so that a straight axis direction of the slit antenna is parallel to the drying furnace width direction.

  The slit antenna may be arranged such that a straight axis direction of the slit antenna is inclined with respect to the drying furnace width direction.

The waveguide, the shape of the cross section perpendicular to the traveling direction of the microwave is rectangular, the short sides of the rectangular front Kidan surfaces are perpendicular to the conveying direction, the rectangular the long side of the cross-sectional surface may be parallel to the conveying direction.

  The coaxial antenna has a center conductor that is a hollow or solid metal tube, and an outer peripheral conductor that is a hollow metal tube provided further outside the center conductor, and the layer to be dried of the center conductor The end on the side protrudes by a length corresponding to one-fourth of the wavelength of the microwave propagated in the coaxial antenna from the end on the layer to be dried side of the outer conductor. Is preferred.

  It is preferable that the positional relationship between the central conductor and the outer conductor of the coaxial antenna is fixed by a spacer formed of an inorganic material ceramic having a dielectric loss coefficient of less than 0.02.

  The tip or notch of the waveguide or the tip of the coaxial antenna and at least the opening of the slit antenna are formed of an inorganic material ceramic having a dielectric loss coefficient of less than 0.02. A ceramic cover is preferably provided.

  It is preferable to provide a vibration mitigation mechanism for mitigating vibrations that occur as the object to be dried is conveyed with respect to the waveguide or the coaxial antenna and the slit antenna.

  As the vibration relaxation mechanism, a slide waveguide having a slide mechanism that enables axial sliding between the waveguide, the coaxial antenna or the slit antenna, and the microwave oscillator, or It is preferable to dispose at least one of the flexible waveguides having a metal bellows portion.

  As the vibration relaxation mechanism, it is preferable that an elastic member is provided on a part of the support body that supports the waveguide or the coaxial antenna and the slit antenna.

  It is preferable that the waveguide or the coaxial antenna and the slit antenna are arranged side by side in the transport direction so that the heating range is continuous in the transport direction.

  The waveguide may be branched so that the heating range is continuous in the transport direction.

  A dustproof gas is introduced into the waveguide or the coaxial antenna and the slit antenna, and a positive pressure is applied to the waveguide or the coaxial antenna and the slit antenna. It is preferable that

  A taper portion having a cross-sectional area that is perpendicular to the transport direction may be provided at the upstream end of the waveguide or the coaxial antenna in the transport direction.

  A tapered portion having a height that decreases toward the upstream side in the transport direction may be provided at an end of the slit antenna on the upstream side in the transport direction.

  One or a plurality of rollers may be further provided for the tapered portion of the slit antenna.

  The microwave drying apparatus includes: an impedance of the microwave oscillated from the microwave oscillator between the microwave oscillator and the plurality of waveguides or the plurality of coaxial antennas; It is preferable to further include an automatic matching unit that performs matching with the impedance of the microwave reflected at the microwave oscillator.

  The inorganic material ceramics may be selected from the group consisting of alumina, silicon nitride, sialon, aluminum nitride, boron nitride, and mixtures thereof.

Moreover, in order to solve the said subject, according to another viewpoint of this invention, when conveying a to-be-dried object with a conveyor, it is contained in the to-be-dried object by spraying a hot air with respect to the to-be-dried object. A microwave drying method carried out for a hot-air drying furnace for reducing moisture, wherein a microwave used for drying the object to be dried is oscillated and the object to be dried is conveyed. A plurality of waveguides each having a heating range in which the object to be dried is heated by the microwave to a depth including the lowermost layer of the object to be dried, and the conveyor A plurality of slit antennas provided directly above and having a plurality of openings on the top surface of the waveguide for guiding the microwave, and irradiating the object to be dried from each of the plurality of openings Each of the objects to be dried is irradiated with the microwave, and the heating range of each of the waveguides and the opening of the slit antenna as a whole are the furnaces of the drying furnace. A microwave drying method is provided which is arranged at intervals so as to cover the entire width direction.

Moreover, in order to solve the said subject, according to another viewpoint of this invention, when conveying a to-be-dried object with a conveyor, it is contained in the to-be-dried object by spraying a hot air with respect to the to-be-dried object. A microwave drying method carried out for a hot-air drying furnace for reducing moisture, wherein a microwave used for drying the object to be dried is oscillated and the object to be dried is conveyed. A plurality of coaxial antennas each having a heating range in which the object to be dried is heated by the microwave to a depth including the lowermost layer of the object to be dried with respect to the inside of the dried object layer, and immediately above the conveyor And a plurality of slits for irradiating the object to be dried with the microwaves from each of the plurality of openings. The microwave is applied to the layer to be dried from each of the tenors, and the heating range of each of the coaxial antennas and the opening of the slit antenna are in the furnace width direction of the drying furnace as a whole. A microwave drying method is provided that is spaced apart to cover the whole.

  As described above, according to the present invention, the microwave irradiation member is inserted from the upper part of the layer to be dried to a predetermined position and the microwave irradiation member provided directly above the conveyor is microwaved. , It becomes possible to selectively heat the lower layer portion of the material to be dried charged in the drying furnace.

It is explanatory drawing shown about the flow of the manufacturing method of a general reduced iron. It is explanatory drawing for demonstrating the state of the agglomerate in a drying furnace. It is explanatory drawing which showed the outline of the microwave drying method which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the examination result regarding the heating method using a microwave. It is explanatory drawing for demonstrating the examination result regarding the heating method using a microwave. It is explanatory drawing which showed the structure of the microwave drying apparatus which concerns on embodiment of this invention. It is explanatory drawing shown about the microwave irradiation member which concerns on the 1st reference form of this invention. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the 2nd reference form of this invention. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the 3rd reference form of this invention. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the modification of the microwave irradiation member which concerns on the reference form. It is explanatory drawing shown about the microwave irradiation member which concerns on the 1st Embodiment of this invention. It is explanatory drawing shown about the 1st modification of the microwave irradiation member which concerns on the embodiment. It is explanatory drawing shown about the microwave irradiation member which concerns on the same embodiment. It is explanatory drawing shown about the microwave irradiation member which concerns on the same embodiment. It is explanatory drawing shown about the microwave irradiation member which concerns on the same embodiment.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(About manufacturing process of reduced iron)
Prior to describing the microwave drying apparatus and the microwave drying method according to the embodiment of the present invention, first, the manufacturing process of reduced iron will be described in detail with reference to FIG. Drawing 1 is an explanatory view for explaining the manufacturing process of reduced iron.

  First, iron oxide raw materials such as iron dust (iron oxide powder), iron ore, and powder ore, and reducing materials such as coal, coke, and fine carbon are stored in the hopper 1 and the like in advance. The iron oxide raw material and the reducing material are blended so as to have a preset blending ratio and charged into the pulverizer 2.

  A crusher 2 typified by a vibration mill such as a ball mill crushes the charged iron oxide raw material and the reducing material to a predetermined particle size while mixing them. The particle diameters of the iron oxide raw material and the reducing material after pulverization can be set to values suitable for a solid reduction furnace such as a rotary hearth furnace, a fluidized bed furnace, and a shaft furnace used for producing reduced iron. The mixture of the pulverized iron oxide raw material and the reducing material is conveyed to the kneader 3.

  The kneader 3 kneads the mixture pulverized to a predetermined particle size by the pulverizer 2. Moreover, the kneading machine 3 may perform a humidity control process for adding water to the mixture until the water content is suitable for a solid reduction furnace used for producing reduced iron. As an example of the kneading machine 3, for example, a mix muller can be cited. The mixture kneaded by the kneader 3 is conveyed to the molding machine 4.

  A molding machine 4 such as a pan pelletizer (dish granulator), a double roll compressor (briquette making machine), and an extrusion molding machine molds a mixture containing an iron oxide raw material and a reducing material, and agglomerates such as pellets. It is a chemical. Here, the agglomerated material refers to pellets, briquettes, extruded products that have been cut by extrusion molding, and granular materials / agglomerated materials such as mass-adjusted agglomerated materials. When the molding machine 4 is dried and heat-reduced, which will be described later, for example, when charged into the melting furnace 7 in the hot state, the above mixture is adjusted so as to have a size larger than the particle size so as not to be scattered by the rising gas flow in the furnace. Agglomerates. The produced agglomerated material is charged into the drying furnace 5.

  The drying furnace 5 dries the agglomerated material and has a moisture content suitable for the heating and reducing process described later (in other words, a moisture content suitable for each solid reduction furnace used for producing reduced iron: for example, 1% And so on. The agglomerated product having a predetermined moisture content is conveyed to a solid reduction furnace 6 to be described later.

  For example, the solid reduction furnace 6 such as a rotary hearth furnace (RHF), a fluidized bed furnace, a shaft furnace, etc., heats the agglomerate charged in a heating atmosphere such as an LNG burner or a COG burner. Reduce to iron reduced. The solid reduction furnace heats the agglomerate to, for example, about 1000 to 1300 ° C. to reduce the agglomerate and produce reduced iron. The manufactured reduced iron is conveyed to the melting furnace 7. In the melting furnace 7, the reduced iron produced in the solid reduction furnace 6 is melted to produce hot metal. The produced hot metal is processed into various steel products through a desulfurization / decarburization process, a secondary refining process, a continuous casting process, a rolling process, and the like.

(Outline of drying method using microwaves)
In the manufacturing process of reduced iron as described above, the drying furnace 5 is usually a tunnel-shaped furnace that dries the agglomerated material using hot air. Inside the drying furnace 5, normally, agglomerates such as briquettes are charged until the height reaches, for example, about 250 mm, and the inside of the furnace is conveyed by a mesh-like metal conveyor. Each agglomerated material to be conveyed has various sizes depending on the type of the reduction furnace or melting furnace, for example, a roughly spherical shape of about 10φ to 20φ, or 30φ to 50φ × thickness of about 25 mm. The load is about 300 kg / m ^{2 on} the mesh conveyor by being stacked up to about 250 mm in height. In the course of this conveyance, the moisture in the agglomerated material is removed by hot air, and the moisture content of the agglomerated material is controlled to a desired value. In addition, as described above, in order to prevent ignition of coal components contained in the agglomerated material, there is a restriction that the hot air used is about 200 ° C. or less.

  However, as a result of investigating the remaining state of moisture in the drying furnace by the present inventors, as schematically shown in FIG. 2, in the drying with hot air from above, the upper layer part of the agglomerate layer is dried. In the lower layer portion (portion close to the mesh conveyor), it was revealed that the residual amount of water is large, and the agglomerated material in the lower layer portion is often poorly dried. Due to such factors, the yield of the average drying rate of the agglomerated material decreases, and the drying time must be lengthened to increase the degree of drying.

  Therefore, the present inventors have intensively studied a method for selectively heating the lower layer portion of the agglomerate layer. For example, the following are the events that have become a concern in this study.

In other words, the floor surface of the drying furnace is a mesh-like conveyor using metal, so if microwaves are simply irradiated from below the conveyor, the irradiated microwaves are reflected by the conveyor and agglomerated. The chemical cannot be heated. It is also conceivable to change the material of the conveyor to a material that absorbs less microwaves, such as Teflon (registered trademark) or nylon, but such a material is more expensive than a metal mesh belt, The cost is high and the load of about 300 kg / m ² cannot be withstood. In addition, even when microwaves are irradiated from above, the agglomerate previously located in the lower layer may be heated by inverting the agglomerate layer in the drying furnace. However, if such an upside down is carried out, the agglomerated product may be crushed by colliding with each other, and the agglomerated product may be pulverized.

  Therefore, in order to sufficiently dry the agglomerated material under the condition that the material to be dried such as agglomerated material is moving in the furnace (that is, the material to be dried is not stationary). In addition, it is necessary to study a method that can efficiently irradiate the lower part of the agglomerate with high-power microwave of kW class, for example, while maintaining the wear resistance of the microwave irradiation member. It was.

  As a result, as schematically shown in FIG. 3, the agglomerate located in the lower layer by microwave heating is supplied to the lower layer part of the agglomerate layer without passing through the mesh conveyor. The inventors have conceived four types of methods capable of selectively heating the above.

  By using the drying method schematically shown in FIG. 3, the drying progress of the lower layer portion of the agglomerated layer is improved, the average drying rate of the agglomerated material is improved, and the drying time is shortened. As a result, productivity of the drying process can be improved.

  Prior to describing the microwave drying apparatus and the microwave drying method according to the embodiment of the present invention, various examination results on the method for drying an agglomerate using microwave heating by the present inventors will be described with reference to FIGS. This will be specifically described with reference to FIG.

<Examination of the range covered by microwave heating>
The present inventors conducted the following experiment in order to examine the range covered by microwave heating. FIG. 4 schematically shows an experimental apparatus for verifying the range covered by microwave heating when the agglomerate (briquette) is irradiated with microwaves from above.

  As shown in FIG. 4, the present inventors laminated an undried briquette (used in actual operation) of about 40φ × 20 mm on a metal container and placed it in the chamber. At this time, a thermocouple is inserted into a briquette located at a substantially central portion of the metal container, and between each layer (for example, between layer A and layer B, between layer B and layer C in the lower diagram of FIG. 4). ... etc.) was also equipped with a thermocouple to monitor the temperature rise. In addition, a 3.0 kW microwave oscillator capable of radiating a 2.45 GHz microwave, a power monitor capable of measuring the incident microwave output and reflected microwave output to the chamber, and reducing the reflected microwave For this purpose, a microwave output from the automatic aligner was irradiated from above the chamber through the waveguide. In this experiment, the microwave incident power was 600 W, and the microwave irradiation time was 60 seconds.

  As a result, in the thermocouple inserted in the briquette located in the layer A shown in the lower diagram of FIG. 4 and the thermocouple inserted between the layers A and B, a clear temperature rise was confirmed, and the briquette located in the layer B was confirmed. However, although it was not as high as the briquette located in the layer A, an increase in temperature was confirmed. However, in the briquettes located below the layer C, no temperature increase could be confirmed. This experimental result indicates that when microwaves are irradiated from above the agglomerated material, the range of heating by microwaves is at most from the outermost layer to the second layer.

By the way, the microwave energy P _abs per unit volume absorbed by the substance is expressed as the following Expression 11. As can be seen by referring to Equation 11 below, the microwave energy P _abs per unit volume absorbed by the substance to be heated (substance to be heated) depends on the conductivity, dielectric constant and permeability of the substance to be heated. You can see that Therefore, it can be said that P _abs represented by the following formula 11 is an amount related to the microwave absorption efficiency of the heated material.

Here, in Equation 11 above,
σ: Conductivity of heated material [S / m]
f: Microwave frequency [Hz]
ε ₀ : dielectric constant in vacuum [F / m]
ε ″: Imaginary part of relative permittivity of heated material μ ₀ : Permeability in vacuum [H / m]
μ ”: Imaginary part of relative permeability of heated material E: Electric field strength formed by microwave [V / m]
H: intensity of magnetic field formed by microwave [A / m]
π: Pi ratio.

  The values of the imaginary part ε ″ of the relative dielectric constant are collectively shown below for the iron oxide and carbon material (reducing material) that are the raw materials of the agglomerated material and the refractory furnace materials that are generally used.

Imaginary part of dielectric constant ε ”
Alumina, which is a typical refractory furnace material: 0.004 to 0.01
・ Powdered carbon powder: 10-50
・ Iron oxide: 0.1-10

  As is clear from the above, the iron oxide and carbon material used as the raw material for the agglomerate have a large value of the imaginary part ε ″ of the relative dielectric constant relative to the refractory furnace material generally used in a drying furnace or the like, The oxide and carbon material (reducing material) can absorb more microwave energy, and the value of alumina, which is a typical refractory furnace material, compared to the values of iron oxide and carbon powder, The value is about 1/1000, and it can be seen that the refractory furnace material does not absorb much microwave energy, so when the microwave is irradiated in the furnace in which the agglomerates are inserted, There is little energy supply to the furnace wall etc. which are coat | covered with the furnace material, and it becomes possible to raise only the temperature of the agglomerate which is a raw material efficiently, suppressing the raise in furnace temperature.

  However, in the experimental situation where the microwave as shown in FIG. 4 is irradiated to the free space in the furnace due to the characteristics as described above, the microwave irradiated from above is agglomerated in the upper layer region. It is considered that the microwave does not penetrate into the lower layer portion that needs to be supplied with heat to promote drying and is absorbed by the chemicals very well. Therefore, the present inventors, as in the prior art, heat the agglomerate located in the lower layer part when microwaves are irradiated from the furnace ceiling, side walls, or furnace bottom toward the space in the furnace. Judged that it is not possible.

  By the way, when the microwave is absorbed by the material due to dielectric loss, the energy of the microwave is converted into heat, and as a result, the material that has absorbed the microwave is heated. At this time, how much the microwave penetrates into the substance can be calculated by the following equation 12.

Here, in the above equation 12,
δ: microwave penetration depth [cm]
λ: wavelength of microwave in free space [cm]
ε ': relative permittivity of the substance (real part)
tan δ: the dielectric loss tangent of the substance.
Further, tan δ can be calculated by (ε _r ′ / ε _r ″) using the dielectric constant ε _r ′ and the dielectric loss coefficient ε _r ″ of the substance.

As a result of further experiments by the present inventors, the briquette is a lump of 30φ to 50φ × thickness 25 mm, and there is a gap between each briquette, and in the briquette being transported, the gap between each briquette Since the state changes, the microwave heating range is expanded, and the range up to 10 times the penetration depth δ obtained by Equation 12 is an effective heating range (hereinafter also referred to as δ _eff ). It became clear. When the penetration depth δ is calculated from the physical property values of the briquette, the magnitude is about 1 cm, so the effective heating range δ _eff by microwave heating is about 10 cm. Therefore, it was also clarified that microwave irradiation from the side face cannot heat the entire lower layer of the drying furnace having a width of about 2 to 2.5 m and a transport distance of about 20 to 30 m used in the operation.

  Therefore, as a result of further studies based on the knowledge obtained by the experiments as described above, the present inventors have come up with a microwave irradiation method capable of heating the entire lower layer portion of the drying furnace. The inventors have arrived at a microwave drying apparatus and a microwave drying method as described below.

  FIG. 5 is a graph schematically showing the relationship between the moisture content (%) after drying the agglomerated material and the crushing strength of the agglomerated material. In producing the agglomerated material, starch-based paste such as corn starch is used as a binder to achieve the required strength. The starch-based paste increases in strength as it is dried as illustrated in FIG. . Therefore, the crushing strength of the agglomerated product can be increased without changing the binder amount by improving the drying rate of the entire agglomerated product by the method described below. As a result, it is possible to reduce the amount of agglomerated material that cannot be used by being crushed during transportation, and the yield can be improved. Further, by improving the drying rate, it is possible to reduce the amount of the binder to be added in order to obtain the same strength, and thus it is possible to reduce the manufacturing cost.

(About the microwave used)
Next, a microwave used in the microwave drying apparatus and the microwave drying method according to the embodiment of the present invention will be briefly described.

  The microwave generally refers to an electromagnetic wave having a wavelength of 1 mm to 1 m and a frequency of 300 MHz to 300 GHz. However, as noted in the method for heating an agglomerate according to the present embodiment, when microwaves are used as heating means (so-called microwave heating is performed), microwaves are so-called ISM (Industry- Science-Medical) refers to an electromagnetic wave in a frequency band belonging to the band.

  In the embodiment of the present invention described below, there is no particular limitation as long as the electromagnetic wave has a frequency belonging to the IMS band. For example, a 2.45 GHz band (2.40 GHz to 2.50 GHz), a 5.8 GHz band (5. 725 GHz to 5.875 GHz) and frequencies belonging to the 24 GHz band (24.0 GHz to 24.25 GHz) can be selected as appropriate. However, since the penetration of microwaves into the object to be heated is proportional to the wavelength of the microwaves as represented by the above equation 12, the penetration depth δ in the 2.45 GHz band is one for the microwaves in the ISM band. The raw material briquette can be heated over the entire number of coaxial antennas or waveguides and the entire width of the drying furnace. In addition, 2.45 GHz is widely used for microwave ovens and other microwave heating applications, and the device is inexpensive, and it is possible to radiate high power up to several tens of kW with one oscillator. Also, the equipment cost of the present invention that requires a large output of kW class can be introduced at a lower cost than the other two frequency devices. For this reason, the ISM band microwave device used in the present invention is preferably capable of oscillating 2.45 GHz microwave.

(About the configuration of the microwave dryer)
Next, the configuration of the microwave drying apparatus according to the embodiment of the present invention will be described in detail with reference to FIG. FIG. 6 is an explanatory diagram for explaining the configuration of the microwave drying apparatus according to the embodiment of the present invention.

  The microwave drying apparatus 10 according to the present embodiment blows hot air from above the raw material and passes the hot air from the upper side to the lower side of the raw material in the process of conveying the powder or small block raw material by a mesh conveyor. Thus, it is used for a hot-air type tunnel drying furnace that reduces moisture contained in the raw material.

  As shown in FIG. 6, the microwave drying apparatus 10 according to the present embodiment mainly includes a microwave oscillator 101, a circulator 103, an automatic matching unit 107, and a microwave irradiation member 109. Are connected by a waveguide 111. In FIG. 6, a support mechanism for supporting each member such as the microwave guiding member 109 and the waveguide 111 is not shown.

  The microwave oscillator 101 is a device that oscillates a microwave having a frequency belonging to, for example, an ISM band. The microwave oscillator 101 is preferably a device capable of oscillating microwaves having a kW class output. For example, a microwave having a frequency belonging to a 2.45 GHz band is output to the circulator 103 described later by the microwave oscillator 101. As this microwave oscillator 101, a publicly known one can be appropriately selected and used.

  The circulator 103 performs a microwave progress control using, for example, a magnet, so that the microwave input to the circulator 103 is changed from the incident wave output from the microwave oscillator 101 to the automatic matching unit 107 described later. It separates into the reflected wave that has returned. The circulator 103 guides the separated incident microwave toward the automatic matching unit 107 described later, and guides the reflected microwave toward the isolator 105 side. Thereby, the reflected microwave can be absorbed by a dummy load (for example, water) provided in the isolator 105 and can be prevented from returning to the microwave oscillator 101 side. By providing such a circulator 103, the microwave drying apparatus 10 according to the present embodiment can output a stable microwave. As this circulator 103, a known circulator can be appropriately selected and used.

  The automatic matching unit 107 reduces the reflected wave from the load side by matching the impedance on the incident side with the impedance on the load side (that is, the raw material layer side made of agglomerated material), and the reflected wave is almost zero. It is a device. The automatic matching unit 107 measures the phase and intensity of the reflected electric field and automatically performs impedance matching, thereby realizing the reduction of the reflected wave as described above.

  The object to be dried by the microwave drying apparatus 10 according to the present embodiment is a small lump raw material such as an agglomerated material being conveyed in the drying furnace 5. Therefore, the contact state between the moving small lump material and the microwave irradiation member 109 to be described later constantly changes, and the impedance on the load side changes, so that the microwave irradiation efficiency changes. By providing an automatic matching unit 107 and realizing automatic matching processing according to the impedance on the load side, it is possible to stably and efficiently irradiate the raw material layer with microwave energy from the microwave irradiation member 109 described later. It becomes.

  The microwave irradiation member 109 is a member that irradiates the microwave to the lower layer portion of the raw material layer in order to selectively heat the lower layer portion of the raw material layer made of agglomerated material in the hot air drying furnace 5. The configuration of the microwave irradiation member 109 will be described in detail later.

  The waveguide 111 is a tube that guides a microwave to a desired location. The shape of the waveguide 111 may be appropriately determined in consideration of the waveguide characteristics of the microwave, etc., and the waveguide 111 itself also depends on the frequency and output intensity of the microwave to be used. A well-known thing can be selected suitably.

(First reference form)
<Configuration of microwave irradiation member>
Then, the structure of the microwave irradiation member which concerns on the 1st reference form of this invention is demonstrated in detail, referring FIGS. 7-12. 7-12 is explanatory drawing shown about the microwave irradiation member which concerns on this reference form.

  As illustrated in FIG. 7, in the present embodiment, the waveguide 111 that is a hollow metal tube is used as the microwave irradiation member 109 and is formed of an agglomerated material that is conveyed in the depth direction of the paper in FIG. 7. A waveguide 111 is inserted into the raw material layer from above the drying furnace 5. In FIG. 7, only one of the waveguides 111 inserted into the drying furnace 5 is shown for easy understanding, but the drying furnace 5 includes a plurality of waveguides. 111 is inserted from above. The waveguide 111 is inserted so as to be substantially perpendicular to the bottom surface of the drying furnace 5 formed of a mesh conveyor.

  The cross-sectional shape of the waveguide 111 used as the microwave irradiation member 109 (cross-sectional shape in a direction parallel to the conveying direction of the raw material layer) and the size of the cross-section guide microwaves having a desired frequency and intensity. For example, the cross-sectional shape is preferably rectangular (rectangular waveguide) or circular (circular waveguide).

  In particular, in a rectangular waveguide, when the wavelength in a free space of a microwave that can be transmitted is λ and the length of the long side of the rectangular waveguide is a, the relationship expressed by the following Expression 13 is satisfied. For example, transmission in the TE10 mode, which is a fundamental wave of microwaves, is possible. At this time, the short side b of the rectangular waveguide has no restriction on microwave transmission, and the short side b is reduced under the condition that the electric field strength in the waveguide does not exceed the dielectric breakdown voltage of the internal medium (internal gas). can do. Therefore, in the rectangular waveguide, it is possible to make the width of the waveguide corresponding to the short side installed substantially perpendicular to the conveying direction when inserted into the drying furnace sufficiently smaller than that of the cylindrical waveguide. . That is, in the rectangular waveguide, the influence on the conveyance of the briquette due to the waveguide insertion can be reduced. In the present embodiment, it is preferable to use the rectangular waveguide rather than the cylindrical waveguide. .

    λ / 2 <a <λ (Formula 13)

  Since the agglomerated material is moving in the transport direction inside the drying furnace 5, the waveguide 111 is not resistant to the agglomerated material flow (i.e., the agglomerated material flow is not corrected). Inserted in the raw material layer (so that the area with respect to it is reduced). For example, when the cross-sectional shape of the waveguide 111 is rectangular, the long side of the rectangular shape is substantially parallel to the transport direction, and the short side of the rectangular shape is substantially orthogonal to the transport direction. Inserted into the raw material layer. Moreover, in order to reduce the conveyance resistance of the agglomerated material, the waveguide 111 may be inclined so that the lower end faces the downstream side in the conveyance direction of the raw material layer.

  In addition, the waveguide 111 takes into consideration the load per unit surface that is received from the agglomerated material being transferred, so that the cross-sectional shape has a strength that prevents buckling deformation due to the load. Manufactured using various metals such as aluminum (Al), nonmagnetic austenitic stainless steel (SUS), and alloys containing these. Further, when the waveguide 111 itself is fixed to the upper part (for example, the ceiling) of the place where the drying furnace 5 is installed, the waveguide itself receives a load from the agglomerated material and buckles and deforms. However, it is preferable to have strength that does not bend in the transport direction.

  The inside of the raw material layer of the drying furnace 5 has a temperature of about 80 ° C. or higher at the lower layer portion and is in a high temperature and high humidity state having a humidity close to about 100%, and the agglomerated material is moving under such conditions. . Therefore, in order to prevent the occurrence of arcing due to moisture entering the inside of the waveguide 111 and to prevent the intrusion of dust into the inside of the waveguide 111, dry air, dry nitrogen, dry argon, etc. It is preferable to introduce dustproof gas into the hollow waveguide so that a positive pressure is applied to the waveguide 111.

Further, a ceramic cover 113 is provided at the tip of the waveguide 111 used as the microwave irradiation member 109, and microwaves are radiated from the periphery of the ceramic cover, thereby widening the heating range around the waveguide. It is preferable to do so.
Here, as shown in FIG. 7, the shape of the ceramic cover 113 is a rectangular parallelepiped when the cross-sectional shape of the waveguide 109 is rectangular, and is cylindrical when the cross-sectional shape of the waveguide 109 is circular. It is preferable to do.

The ceramic cover 113 is made of an inorganic material ceramic that has a low absorption of microwaves as a heating source, can be used even in a high temperature and high humidity state, and has strength, wear resistance, and workability that can withstand contact with an agglomerated material. It is formed. The inorganic material ceramic used for the ceramic cover 113 preferably has a dielectric loss coefficient ε _r ″ related to microwave absorption characteristics of less than 0.02. The dielectric loss coefficient ε _r ″ is less than 0.02. This makes it possible to suppress self-heating of the inorganic material ceramics due to microwave absorption.

Examples of such inorganic material ceramics include alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), sialon (SiAlON, chemical formula: Si ₃ N ₄ · Al ₂ O ₃ ), aluminum nitride (AlN), Examples include boron nitride (BN). The ceramic cover 113 may be manufactured by using these inorganic material ceramics alone, or the ceramic cover 113 may be manufactured by mixing these inorganic material ceramics.

  In the present embodiment, the waveguide 111 is inserted from above the drying furnace 5 to such a depth that the heating range of the waveguide 111 reaches the lowest layer of the raw material layer. By inserting the waveguide 111 into the raw material layer in this way, it is possible to selectively heat the agglomerate located in the lower layer portion of the raw material layer by the microwave energy irradiated from the tip of the waveguide 111. It becomes.

At this time, if the separation distance between the tip of the waveguide 111 and the mesh conveyor becomes too small, microwave radiation from the tip of the waveguide cannot be performed. Therefore, as shown in FIG. 8 for example, it is preferable that the distance L ₁ between the waveguide tip and reticulated conveyor, more than a quarter of the wavelength of the microwaves λ utilized as a heat source .

Result of studies by the present inventors, by setting the distance L ₁ lambda / 4 or more, the proportion of the microwave radiated from the waveguide tip can be 70% excess, from reticulated conveyor It has been found that the proportion of reflected microwaves can be less than 30%. When the ratio of the reflected microwaves is large, the oscillation wavelength of the microwaves is disturbed due to interference, so that the operation of the automatic matching unit 107 may become unstable. On the other hand, if the ratio of the reflected microwave is about 30%, the reflected microwave can be made almost zero by phase matching using the automatic matching unit 107. In addition, when the ratio of reflected microwaves is large, microwaves are radiated by pushing back a large reflected power, which may cause abnormal heating in parts that are not normally heated, such as the joints of waveguides. There is a possibility that the operational stability of the microwave drying apparatus 10 may be reduced.

Furthermore, even when providing a ceramic cover 113 to the distal end of the waveguide 111, distance L ₁ is preferably a lambda / 4 or more. Furthermore, if the tip of the waveguide 111 providing a ceramic cover 113, as shown in FIG. 9, the distance L ₂ between the tip and the mesh-like conveyor ceramic cover 113, the degree of agglomerate does not enter It is preferable to set it as the magnitude | size (For example, magnitude | size about the average height of an agglomerate).

  In this reference embodiment, when a plurality of waveguides 111 as the microwave irradiation members 109 are arranged in the width direction of the drying furnace 5, the agglomerated material is removed from the furnace of the drying furnace 5 by the plurality of arranged waveguides 111. In order to heat uniformly in the width direction, at least two of the plurality of waveguides 111 are arranged at different positions in the furnace width direction of the drying furnace.

  In addition, in order to prevent the arranged plurality of waveguides 111 from resisting the flow of the agglomerated material, for example, as shown in FIG. 10, in the projection view shown in FIG. The conveyance direction position of the waveguide should not be the same. That is, in the view of the drying furnace 5 shown in FIG. 10, the width direction of the drying furnace 5 is divided into five regions A to E for convenience, the conveying direction of the raw material layer is the X direction, and the drying furnace. The width direction is defined as the Y direction. In this case, in this reference embodiment, the waveguides 111 are distributed and arranged so that the X-direction positions of the waveguides 111 belonging to adjacent regions (for example, the region A and the region B) are not the same. .

  Further, for example, as shown in the projection view shown in FIG. 11, when the drying furnace 5 is viewed in the conveyance direction, the range heated by each waveguide 111 (heating range) is the width direction of the drying furnace 5. It is preferable to arrange the waveguides 111 at intervals so as to cover substantially the whole. At this time, it is preferable to determine the arrangement interval of the waveguides 111 so that the heating ranges of the respective waveguides 111 overlap each other. In other words, the maximum width of the heating range by the single waveguide 111 is L, the width of the drying furnace 5 is W, and the number of waveguides in the width direction of the drying furnace 5 in the projection view shown in FIG. When N is N, it is preferable to determine the maximum number of waveguides in the width direction of the drying furnace 5 so as to satisfy L × N ≧ W.

Specifically, when 10 times the microwave penetration depth δ shown in Equation 12 is considered as the effective heating range δ _eff , the maximum width L of the heating range by the single waveguide 111 is 2 × [delta] _eff becomes, so that the width direction distance between the respective waveguides adjacent in the width direction is less than L, and preferably to determine the arrangement interval in the width direction of the waveguide 111. By arranging the waveguides 111 at such intervals, the agglomerated material for the entire width of the drying furnace can be heated without unevenness.

  When the interval between the plurality of waveguides is larger than the above L, the heating range by the microwave does not reach the entire width of the furnace, and uneven heating of the agglomerated raw material can be performed in the width direction of the furnace. It is not preferable to lead to. However, since the drying of the raw material is improved in the portion heated by the microwave, the drying as the average value of the entire raw material is improved according to the number of inserted waveguides.

  Also, if the efficiency of hot air drying in the furnace width direction is different as a characteristic of the drying furnace, a waveguide is inserted only in the part where drying efficiency is inferior and drying of the agglomerated raw material is delayed, and microwave irradiation is performed It is also effective to do.

  Further, how to arrange each waveguide 111 is not particularly limited. For example, based on knowledge about the uneven state of residual moisture in the drying furnace 5, the unevenness can be eliminated. What is necessary is just to determine the arrangement | positioning position of a waveguide. Therefore, for example, in FIG. 11, a plurality of waveguides 111 may be disposed in the same region.

  For example, as shown in FIG. 12, a tapered portion 115 whose width becomes narrower toward the upstream side in the transport direction may be provided on the upstream side in the transport direction of the short side of the waveguide 111. By providing such a tapered portion 115, it is possible to further reduce the agglomerated material transport resistance by the waveguide 111. Further, the tapered portion 115 may be provided not only on the upstream side in the transport direction of the short side of the waveguide 111 but also on the downstream side in the transport direction.

  The microwave drying apparatus 10 and the microwave drying method according to the first reference embodiment of the present invention have been described in detail above with reference to FIGS.

<Modification of the first reference embodiment>
Next, a modification of the microwave irradiation member according to the first reference embodiment of the present invention will be described with reference to FIGS. 13A to 18B. FIG. 13A to FIG. 18B are explanatory views for explaining a modification of the microwave irradiation member according to the first reference embodiment of the present invention.

[Microwave irradiation from the side of the waveguide]
The waveguide 111 in the above description has an opening at the end (that is, the bottom surface of the waveguide 111 in FIG. 7 or the like) facing the mesh conveyor when the waveguide 111 is inserted into the raw material layer. The microwave was irradiated from this bottom surface. When an opening is provided in the bottom surface of the waveguide 111, the waveguide 111 is formed in order to prevent the agglomerates and the like from entering the waveguide 111 while expanding the heating range around the waveguide 111. It was preferable to provide a ceramic cover 113 made of an inorganic material ceramic at the tip of the ceramic.

  Since such inorganic material ceramics has a hardness that can withstand the friction of the agglomerated material, it takes time to process the ceramic cover 113. Therefore, for example, as shown in FIG. 12, when performing shape processing into a tapered shape or the like for reducing resistance so as not to hinder the transportation of the agglomerated material, the manufacturing costs of the waveguide and the ceramic cover increase. End up.

  Therefore, in this modification, not the bottom surface of the waveguide 111 but the side surface of the waveguide 111 (more specifically, when the waveguide 111 is inserted into the material layer, it becomes parallel to the material layer transport direction. A method of forming a notch on the side surface and irradiating microwaves from the side surface will be described.

  FIG. 13A schematically shows the distal end portion of the waveguide 111 according to this modification. In the waveguide 111 shown in FIG. 13A, a tapered portion 115 is provided on the upstream side in the transport direction of the raw material layer. Further, as shown in the diagram on the left side of FIG. 13A, when the waveguide 111 is inserted into the raw material layer, the side surface that is parallel to the raw material layer transport direction of the drying furnace (that is, parallel to the paper surface of FIG. 13A). On the side surface, a notch 151 is formed.

  By forming such a notch 151 on the side surface of the waveguide 111, the notch 151 becomes a microwave radiation window, and the microwave is irradiated from the notch 151 to the raw material layer. Become.

In order to prevent the agglomerate from entering the inside of the waveguide 111 from the notch 151, as shown in the diagram on the right side of FIG. 13A, a plate-like ceramic formed of the inorganic material ceramic as described above It is preferable to cover the notch 151 with the cover 153 .

  In the drying furnace 5, since the agglomerated material constituting the raw material layer is dried by supplying hot air from above the raw material layer, more moisture remains as it goes to the lower layer of the laminated agglomerated material. Become. Therefore, in order to further improve the drying effect by microwave irradiation, it is preferable to irradiate the raw material layer with microwaves as much as possible, and the cutout portion 151 is guided near the lower layer portion as shown in FIG. 13B. It is desirable to provide up to the tip of the tube. Further, since the metal portion 111a on the bottom surface of the waveguide 111 is a microwave reflector, the distribution of the emitted microwaves is changed by changing the width A of the metal portion 111a on the bottom surface shown in FIG. 13C. Will be.

  More specifically, by reducing the width A of the bottom surface portion of the waveguide 111 as shown in FIG. 13D, compared to the case shown in FIG. It is also possible to do so. However, since the width of the bottom metal portion 111a affects the impedance of the microwave radiating portion, it is desirable that the width of the metal portion 111a be an appropriate width so that the reflection of the microwave to the waveguide does not become so large. It is desirable to design the width A so that the amount of reflected microwaves is reduced according to the electromagnetic property values (dielectric constant, magnetic permeability, conductivity, etc.) of the chemicalizing raw material, the size of the agglomerated raw material, the packing density, etc. .

  Note that a member made of a material that does not absorb microwaves may be present on the bottom surface of the waveguide 111. Therefore, as shown in FIGS. 13C and 13D, a ceramic cover 153a may be provided for dust prevention. Further, as shown in FIG. 13D, when the width A of the metal portion 111a on the bottom surface is narrowed, it is preferable to provide a ceramic cover 153a on the bottom surface of the waveguide 111.

  Further, as shown in the schematic cross-sectional view taken along the line BB shown in FIG. 13E, the ceramic cover 153 is formed in the notch 151 with a jig using a known material that can be used even inside the drying furnace. Fix it.

  The width W of the cutout portion 151 in the raw material layer conveyance direction is not particularly limited, and may be determined as appropriate according to the size of the waveguide 111, the frequency of the microwave used, the output intensity, and the like. .

  Next, a method for inserting the waveguide 111 according to the present modification into the raw material layer will be described with reference to FIG. FIG. 14 is an explanatory view schematically showing a state in which the waveguide 111 according to this modification is inserted from above the drying furnace 5 when viewed from the side of the drying furnace 5. In FIG. 14, for convenience, the plate-like ceramic cover 153 is omitted.

  When the notch 151 is provided on the side surface of the waveguide 111, the radiation of the notch 151 close to the microwave oscillator 101 (that is, the upper end of the notch 151 in the height direction of the raw material layer). Strength increases. On the other hand, in the drying furnace 5, since the agglomerated material constituting the raw material layer is dried by supplying hot air from above the raw material layer, more moisture remains as it goes to the lower layer of the laminated agglomerated material. It will be. Therefore, in order to further improve the drying effect by the microwave irradiation, it is preferable to irradiate the raw material layer with the microwave as much as possible.

Therefore, in this modification, the thickness of the raw material layer to be heated by the microwave is represented by L, and the position of the upper end of the cutout portion 151 in the raw material layer height direction (that is, the mesh conveyor and the cutout portion 151 in FIG. When the separation distance from the upper end is expressed as L ₃ , it is preferable to insert the waveguide 111 so as to satisfy the relationship L ₃ ≦ L. By setting the thickness L of the raw material layer to be heated by the microwave to a thickness corresponding to the lowermost layer of the raw material layer, the lowermost layer of the raw material layer can be effectively heated by the microwave.

  The method for selecting the thickness L is not particularly limited, and may be appropriately selected based on knowledge obtained from past operation results.

Also, increasing the proportion of the microwave radiated from the cutout portion 151, and, in order to reduce the proportion of the reflected microwaves from the reticulated conveyor, the wavelength of the microwaves utilizing distance L _3, as a heat source ( It is preferable that the wavelength is equal to or more than a quarter of the wavelength (λ) in free space.

On the other hand, in order to prevent an agglomerate from entering between the distal end portion of the waveguide 111 and the mesh container, the separation distance between the distal end portion of the waveguide and the mesh container shown in FIG. L ₄ is preferably set to such a size that the agglomerated material does not enter (for example, the size of the average height of the agglomerated material).

The configuration of the waveguide 111 according to this modification has been described in detail above with reference to FIGS. 13A to 14.
The notch 151 may be formed only on one of the side surfaces parallel to the material layer transport direction of the drying furnace when the waveguide 111 is inserted into the material layer. It is preferable to form both. In addition to the side surface parallel to the material layer conveyance direction of the drying furnace, a notch 151 may be formed on the side surface of the waveguide 111 on the downstream side in the material layer conveyance direction.

[Method of disposing the waveguide in the material layer transport direction]
Next, with reference to FIGS. 15 to 17B, a method of arranging the waveguide according to this modification in the raw material layer transport direction will be described.

  The time t during which the agglomerated material transported inside the drying furnace 5 is heated by the microwave irradiated from one waveguide 111 according to this modification is the notch 151 of the waveguide 111. When the width in the raw material layer transport direction is W [mm] and the transport speed of the agglomerated material is V [mm / sec], it is approximately (W / V) seconds.

  On the other hand, when a microwave is guided using a waveguide, the width of the waveguide is guided in order to prevent a plurality of propagation modes from occurring inside the waveguide and to maintain the transmission efficiency of the microwave. It is often less than the microwave wavelength. For example, when a 2.45 GHz microwave is used, the maximum width of the waveguide in the conveyance direction is about 120 mm. Therefore, when the maximum width of one waveguide is about 120 mm, the time t is extremely short considering the transport speed of a normal mesh conveyor.

  In order to sufficiently dry the agglomerate with microwaves in such a short time, it is conceivable to use microwaves with high output intensity as one of the measures. However, the agglomerates that exist around the waveguide and are heated by microwaves are not necessarily heated uniformly because of differences in heating depending on the position of the agglomerates. In addition, when trying to obtain drying in a short time using a high-power microwave, some agglomerates may be overheated and the volatile components contained in the agglomerates may ignite. is there. Therefore, in order to sufficiently dry the agglomerate by microwave, the microwave is used so that the agglomerate does not overheat, and the microwave action time is lengthened to promote drying. It is important to plan.

  Therefore, in this modification, for example, as shown in FIG. 15, the waveguides 111 are arranged side by side in the material layer conveyance direction so that the heating range of the waveguide 111 is continuous in the material layer conveyance direction. . By adopting such a waveguide arrangement method, it is possible to lengthen the section where the microwave is irradiated, and in turn, it is possible to lengthen the action time of the microwave on the agglomerated material. Become.

  Here, the arrangement method of the waveguides 111 in the transport direction is not particularly limited as long as the heating ranges of the waveguides 111 adjacent to each other in the transport direction are continuous. 111 may be in contact with each other or may be separated from each other. When the adjacent waveguides 111 are arranged apart from each other, it is preferable to provide a cover or the like so that the agglomerated material is not clogged in the space between the adjacent waveguides 111.

  Further, FIG. 15 illustrates the case where two waveguides 111 are continuously arranged in the carrying direction, but three or more waveguides 111 may be arranged continuously in the carrying direction. Needless to say, it is good.

  When arranging the plurality of waveguides 111 in contact with each other, for example, as shown in FIG. 16A and FIG. 16B which is a schematic cross-sectional view taken along the line AA of FIG. The notch 151 may be provided continuously so as to extend over the wave tube 111. In this case, the thickness of the partition d shown in FIG. 16B can be reduced as long as the microwave can be guided.

  Note that the waveguide arrangement method as shown in FIG. 15 is not limited to the waveguide 111 according to the present modification, but also to the waveguide 111 according to the first reference embodiment illustrated in FIG. It goes without saying that it is also possible to apply.

  Moreover, in order to lengthen the action time of the microwave, for example, as shown in FIGS. 17A and 17B, the end of the waveguide is branched to widen the waveguide and the microwave is irradiated. The area may be increased. In this case, a known microwave branching technique such as providing a matching pin 155 and a branch plate 157 for impedance matching inside the waveguide 111 can be applied. In this case, since the microwave guided through one waveguide is guided to each of the two waveguides, the waveguide is guided while satisfying the condition that the width of the waveguide is less than the wavelength of the microwave. It becomes possible to lengthen the heating range of the tube 111. In addition, since the number of the waveguides 111 protruding above the drying furnace 5 can be reduced while expanding the microwave heating range, it is possible to save the space for the equipment.

[Vibration relaxation mechanism]
Next, with reference to FIGS. 18A and 18B, a technique for mitigating vibrations that occur in the waveguide 111 as the agglomerated material is conveyed will be described.

  In the microwave drying apparatus 10 according to the first embodiment of the present invention and the modification thereof, the agglomerated material is stacked on a mesh conveyor to form a raw material layer, and then conveyed from the upper part to the lower part of the raw material layer. Corresponding by inserting the waveguide 111 from above the drying furnace and irradiating the raw material layer lower layer with the microwave to the drying furnace that dries the agglomerate by passing hot air toward it. It is a device that promotes drying of the part.

  At this time, a stress that fluctuates with the transport of the agglomerated material acts on the waveguide 111 inserted from above the drying furnace 5. The stress acting on the waveguide fluctuates because the conveyance speed by the mesh conveyor is not constant but slightly fluctuates, and the density of the agglomerates is not strictly uniform, so it contacts the waveguide. It is conceivable that the state of the agglomerated material changes from moment to moment with the conveyance. When such a fluctuating stress acts on the waveguide 111, the waveguide 111 is vibrated in the direction in which the raw material layer is conveyed. When considering long-term use of the waveguide under such circumstances, there is a concern that such vibration may cause fatigue fracture of the waveguide.

  Therefore, in the microwave drying apparatus 10 according to the present modification, a vibration mitigation mechanism that mitigates vibrations generated along with the transportation of the agglomerated material is installed in the waveguide 111. Examples of such a vibration relaxation mechanism include the following two types of mechanisms.

  As a first vibration mitigating mechanism, a waveguide having a mechanism for mitigating vibration is provided in a portion of the waveguide 111 that guides the microwave generated by the microwave oscillator 101 as close as possible to the vibration generating portion. Is mentioned.

  As a waveguide including a mechanism for reducing vibration, for example, a waveguide having a slide mechanism that enables sliding in the central axis direction of the waveguide (hereinafter referred to as a slide waveguide), or a microwave. For example, a waveguide having a bellows portion formed of a metal material capable of being guided (more preferably, a metal material similar to the waveguide) (hereinafter referred to as a flexible waveguide).

  Since the slide waveguide has a slide mechanism, it can expand and contract in the central axis direction of the waveguide, so that vibration substantially parallel to the central axis direction of the waveguide can be mitigated. In addition, since the flexible waveguide has a metal bellows portion, it can be bent in a direction substantially orthogonal to the central axis direction of the waveguide. On the other hand, it is possible to mitigate vibration in a direction substantially orthogonal to the direction.

  Further, as the second vibration relaxation mechanism, an elastic member may be provided on a part of the support that supports the waveguide 111 that is a microwave irradiation member. By providing an elastic member such as a spring mechanism or a rubber member in a part of the support, vibration generated in the waveguide 111 supported by the support can be reduced by the elastic member.

  By providing the vibration mitigating mechanism as described above, it is possible to mitigate vibrations that occur with the transportation of the agglomerated material, and it is possible to prevent the waveguide 111 from being fatigued.

  In FIG. 18A, a flexible waveguide 161 is installed as a first vibration relaxation mechanism with respect to the waveguide 111, and an elastic member made of, for example, a spring mechanism as a second vibration relaxation mechanism is formed on a part of the support 163. An example in which 165 is provided is shown.

  In the example shown in FIG. 18A, among the waveguides 111 extending from the microwave oscillation mechanism such as the microwave oscillator 101, the circulator 103, and the automatic matching unit 107, a part of the waveguide extending in the vertical direction is used. A flexible waveguide 161 is installed. As described above, the flexible waveguide 161 relieves vibration in a direction substantially orthogonal to the axial direction of the waveguide, and therefore is inserted into the drying furnace 5 as shown in FIG. 18A. Therefore, it is preferable to be installed in a part of the waveguide 111 provided in a substantially vertical direction.

  In FIG. 18A, an elastic member 165 including a spring mechanism is provided on a part of a support 163 that supports the waveguide 111 and extends in the horizontal direction. The spring mechanism is a mechanism that relieves stress by expanding and contracting the spring in the direction of the central axis of the spring.

  As shown in FIG. 18A, the ends of the microwave oscillation mechanism and the support 163 are fixed to a strong member such as a wall. In addition, by installing the flexible waveguide 161 and the elastic member 165 as described above, the waveguide 111 positioned downstream of the flexible waveguide 161 and ahead of the elastic member 165 is structurally separated. It is possible to move freely to some extent. In addition, it is preferable to provide an embedding material 167 for maintaining the hermeticity of the drying furnace 5 while allowing the waveguide 111 to move to some extent while inserting the waveguide 111 into the drying furnace 5. .

  FIG. 18B shows an example in which a slide waveguide 169 is installed instead of the flexible waveguide 161 shown in FIG. 18A. As described above, the slide waveguide 169 relaxes vibrations in the axial direction of the waveguide. Therefore, as shown in FIG. 18B, one of the waveguides 111 extending in the substantially horizontal direction. It is preferable to be installed in the section.

  18A and 18B illustrate the case where one of the flexible waveguide 161 and the slide waveguide 169 is provided for one waveguide 111, the flexible waveguide 161 and the slide are illustrated. A waveguide 169 may be used in combination. 18A and 18B illustrate the case where one flexible waveguide 161, elastic member 165, and slide waveguide 169 are used, a plurality of these members are provided for one waveguide 111. May be installed.

  18A and 18B illustrate the case where the flexible waveguide 161 or the slide waveguide 169 and the elastic member 165 are used together, but depending on the transport speed of the agglomerated material, the elastic member Instead of using 165, only the flexible waveguide 161 or the slide waveguide 169 may be provided.

  18A and 18B, the mechanism for structurally separating the waveguide subjected to fluctuating stress has been described. However, the entire waveguide 111 including the microwave oscillation mechanism is made movable so that vibration can be generated. It may be possible to relax.

  In the above, the modification of the microwave irradiation member which concerns on the 1st reference form of this invention was demonstrated, referring FIG. 13A-FIG. 18B.

(Second reference form)
The microwave drying apparatus 10 according to the first embodiment of the present invention uses the waveguide 111 that is a hollow metal tube as the microwave irradiation member 109, but as the microwave irradiation member 109, It is also possible to use a coaxial antenna. Hereinafter, a microwave drying apparatus and a microwave drying method according to the second reference embodiment of the present invention using a coaxial antenna as a microwave irradiation member will be described in detail with reference to FIGS.

  In addition, since the whole structure of the microwave drying apparatus 10 which concerns on this reference form is the same as that of the microwave drying apparatus 10 which concerns on embodiment of this invention shown in FIG. 6, detailed description is abbreviate | omitted below. To do.

<Configuration of microwave irradiation member>
Below, the structure of the microwave irradiation member which concerns on this reference form is demonstrated in detail, referring FIGS. 19-23. FIGS. 19-23 is explanatory drawing shown about the microwave irradiation member which concerns on this reference form.

  As shown in FIG. 19, in the present embodiment, as the microwave irradiation member 109, the converter 121 connected by the automatic matching device 107 and the waveguide 111, the coaxial antenna 123 connected to the converter 121, Is used.

  The converter 121 is a device that converts the microwave guided in the waveguide 111 so as to propagate through the coaxial antenna 123. The converter 121 can be used by appropriately selecting a known device.

  The coaxial antenna 123 is inserted from above the drying furnace 5 with respect to the raw material layer made of agglomerated material conveyed in the depth direction of the drawing in FIG. In FIG. 19, only one of the coaxial antennas 123 inserted into the drying furnace 5 is shown for easy understanding, but the drying furnace 5 includes a plurality of coaxial antennas 123. Inserted from above. The coaxial antenna 123 is inserted so as to be substantially perpendicular to the bottom surface of the drying furnace 5 formed of a mesh conveyor. Moreover, in order to reduce the conveyance resistance of the agglomerated material, the coaxial antenna 123 may be inclined and installed so that the lower end is directed to the downstream side in the conveyance direction of the raw material layer.

FIG. 20 is an explanatory diagram for explaining the coaxial antenna 123 according to the present embodiment.
As shown in FIG. 20, the coaxial antenna 123 has a two-layer structure including a central conductor 123a and an outer peripheral conductor 123b surrounding the central conductor 123a. Here, as is clear from the cross-sectional view taken along the line AA in FIG. 20, the center conductor 123a is formed using a solid rod-shaped metal, and the outer peripheral conductor 123b is a hollow metal tube. Formed. The central conductor 123a may be formed using a hollow metal tube instead of a solid rod-like metal. Further, as is clear from the cross-sectional view taken along the line BB in FIG. 20, a spacer that holds the center conductor 123a and fixes the positional relationship between the center conductor 123a and the outer conductor 123b in a part of the outer conductor 123b. 123c is provided.

Further, coaxial antenna 123, the tip of the center conductor 123a is formed so as to protrude from the tip of the outer peripheral conductor 123b by a distance _{L 3.} The length of the protrusion distance L _{3 is} a length represented by λ ′ / 4 when the wavelength of the microwave propagated in the coaxial antenna 123 is λ ′. Microwaves propagated in the coaxial antenna 123 are radiated from the periphery of the protruding portion.

  Since the microwave is guided inside the coaxial antenna 123, the cross-sectional shape and the cross-sectional size of the central conductor 123a have a shape and size capable of guiding a microwave having a desired frequency and intensity. For example, it is preferable that the cross-sectional shape is a rectangular shape or a circular shape as shown in FIG. Further, the cross-sectional shape of the outer peripheral conductor 123b is not particularly limited, but is preferably a circular shape as shown in FIG. 14 in order to reduce the conveyance resistance of the agglomerated material.

  The coaxial antenna 123 (especially the outer conductor 123b) is made of copper so that the cross-sectional shape is strong enough to prevent buckling deformation due to the load in consideration of the load per unit surface received from the agglomerated material being conveyed. It is manufactured using various metals such as (Cu), aluminum (Al), nonmagnetic austenitic stainless steel (SUS), and alloys containing these. Further, when the coaxial antenna 123 itself is fixed to the upper part (for example, the ceiling) of the place where the drying furnace 5 is installed, the coaxial antenna itself undergoes a buckling deformation under the load from the agglomerate, It is preferable to have strength that does not bend in the transport direction. The central conductor 123a of the coaxial antenna 123 can be formed using the same metal as that of the outer peripheral conductor 123b.

In addition, since the microwave output from the coaxial antenna 123 is set to be in the order of kW, if a substance having a high electrolytic density and a dielectric loss is used as the material of the spacer 123c, the spacer 123c becomes a microwave. May absorb and self-heat. Moreover, since the use atmosphere of the coaxial antenna 123 is assumed to be 100 ° C. to 200 ° C., a support plate made of Teflon (registered trademark) or the like cannot be used. Therefore, the spacer 123c is preferably formed using a ceramic having a low dielectric loss (for example, a ceramic having a dielectric loss coefficient ε _r ″ of less than 0.02). As an example of such a ceramic, alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), sialon (SiAlON, chemical formula: Si ₃ N ₄ .Al ₂ O ₃ ), aluminum nitride (AlN), boron nitride (BN), etc. The spacer 123c may be manufactured by using alone, or the spacer 123c may be manufactured by mixing these ceramics.

  The inside of the raw material layer of the drying furnace 5 has a temperature of about 80 ° C. or higher at the lower layer portion and is in a high temperature and high humidity state having a humidity close to about 100%, and the agglomerated material is moving under such conditions. . Therefore, in order to prevent the occurrence of arcing due to moisture entering the inside of the coaxial antenna 123, and to prevent the dust from entering the inside of the coaxial antenna 123, a dust-proof gas such as dry air, dry nitrogen or dry argon is used. Is preferably introduced into the hollow coaxial antenna 123 (the central conductor 123a and the outer conductor 123b) so that a positive pressure is applied to the coaxial antenna 123.

  Moreover, since the front-end | tip part (especially protrusion part of the center conductor 123a) of the coaxial antenna 123 collides with what agglomerated material and the agglomerated material pulverized, and friction arises between these, it protects It is preferable to do. Accordingly, as shown in FIGS. 19 and 20, it is preferable to provide a ceramic cover 125 at the tip of the coaxial antenna 123 to protect the tip of the coaxial antenna 123.

The ceramic cover 125 uses an inorganic material ceramic that has a low absorption of microwaves as a heating source, can be used even in a high temperature and high humidity state, and has strength, wear resistance, and workability that can withstand contact with the agglomerated material. It is formed. The inorganic material ceramic used for the ceramic cover 125 preferably has a dielectric loss coefficient ε _r ″ related to microwave absorption characteristics of less than 0.02. The dielectric loss coefficient ε _r ″ is less than 0.02. This makes it possible to suppress self-heating of the inorganic material ceramics due to microwave absorption.

Examples of such inorganic material ceramics include alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), sialon (SiAlON, chemical formula: Si ₃ N ₄ · Al ₂ O ₃ ), aluminum nitride (AlN), Examples include boron nitride (BN). The ceramic cover 125 may be manufactured by using these inorganic material ceramics alone, or the ceramic cover 125 may be manufactured by mixing these inorganic material ceramics.
Here, the shape of the ceramic cover 125 may be a half dome shape as shown in FIG. 19, or may be a cylindrical shape as in the case of the waveguide 109 shown in FIG.

  In this reference embodiment, the coaxial antenna 123 is inserted from above the drying furnace 5 to such a depth that the heating range of the coaxial antenna 123 reaches the lowest layer of the raw material layer. By inserting the coaxial antenna 123 into the raw material layer in this way, it is possible to selectively heat the agglomerate located in the lower layer portion of the raw material layer by the microwave energy irradiated from the tip of the coaxial antenna 123. Become.

  In this reference embodiment, when a plurality of coaxial antennas 123 that are the microwave irradiation members 109 are arranged in the width direction of the drying furnace 5, the agglomerated material is disposed in the furnace width direction of the drying furnace 5 by the plurality of arranged coaxial antennas 123. In order to heat uniformly, at least two of the plurality of coaxial antennas 123 are arranged at different positions in the furnace width direction of the drying furnace.

  In addition, in order to prevent the arranged coaxial antennas 123 from becoming a resistance to the flow of the agglomerated material, for example, as shown in FIG. 21, the conveyance of coaxial antennas at positions adjacent to each other in the projection view shown in FIG. The direction position should not be the same. That is, in the view of the drying furnace 5 shown in FIG. 21, the width direction of the drying furnace 5 is divided into five regions A to E for convenience, the conveying direction of the raw material layer is the X direction, The width direction is the Y direction. In this case, in the present embodiment, the coaxial antennas 123 are arranged in a distributed manner so that the X-direction positions of the coaxial antennas 123 belonging to adjacent regions (for example, the region A and the region B) are not the same.

  Further, in the present embodiment, when a plurality of coaxial antennas 123 are arranged in the width direction of the drying furnace 5, for example, when the drying furnace 5 is viewed in the transport direction as shown in the projection view of FIG. The coaxial antennas 123 are preferably arranged at intervals such that the ranges (heating ranges) heated by the respective coaxial antennas 123 cover substantially the entire width of the drying furnace 5. At this time, it is preferable to determine the arrangement interval of the coaxial antennas 123 so that the heating ranges of the coaxial antennas 123 overlap each other. In other words, the maximum width of the heating range of the single coaxial antenna 123 is L, the width of the drying furnace 5 is W, and the number of coaxial antennas in the width direction of the drying furnace 5 in the projection view shown in FIG. In this case, it is preferable to determine the maximum number of coaxial antennas in the width direction of the drying furnace 5 so as to satisfy L × N ≧ W.

Specifically, when 10 times the microwave penetration depth δ shown in the above equation 12 is considered as the effective heating range δ _eff , the maximum width L of the heating range by the single coaxial antenna 123 is 2 ×. It is preferable to determine the arrangement interval in the width direction of the coaxial antenna 123 so that δ _{eff and} the distance between the respective coaxial antennas adjacent in the width direction is L or less. By arranging the coaxial antennas 123 at such intervals, the agglomerated material for the entire width of the drying furnace can be heated evenly.

  When the interval between the plurality of coaxial antennas is larger than L, the heating range by the microwave does not reach the entire width of the furnace, and heating unevenness of the agglomerated raw material is generated in the width direction of the furnace. It is not desirable to be connected. However, since the drying of the raw material is improved in the portion heated by the microwave, the drying as the average value of the entire raw material is improved according to the number of inserted coaxial antennas.

  Also, if the efficiency of hot air drying in the furnace width direction is different as the characteristics of the drying furnace, insert a coaxial antenna only in the part where drying efficiency is inferior and drying of the agglomerated raw material is delayed, and microwave irradiation Is also effective.

  Further, how the coaxial antennas 123 are arranged is not particularly limited. For example, the coaxial antennas 123 are coaxial so that the deviation can be eliminated based on knowledge about the residual moisture unevenness in the drying furnace 5. What is necessary is just to determine the arrangement | positioning position of an antenna. Therefore, for example, in FIG. 21, a plurality of coaxial antennas 123 may be disposed in the same region.

  For example, as shown in FIG. 23, a tapered portion 127 whose width becomes narrower toward the upstream side in the transport direction may be provided on the end of the coaxial antenna 123 on the upstream side in the transport direction. By providing such a tapered portion 127, it becomes possible to further reduce the agglomerated material transport resistance by the coaxial antenna 123. Further, the tapered portion 127 may be provided not only on the end portion on the upstream side in the transport direction of the coaxial antenna 123 but also on the end portion on the downstream side in the transport direction.

  The microwave drying apparatus 10 and the microwave drying method according to the second reference embodiment of the present invention have been described in detail above with reference to FIGS.

<Modification of second reference embodiment>
Next, a modification of the microwave irradiation member according to the second reference embodiment of the present invention will be described with reference to FIGS. 24 to 25B. FIGS. 24-25B is explanatory drawing for demonstrating the modification of the microwave irradiation member which concerns on the 2nd reference form of this invention.

[Method of disposing the coaxial antenna in the material layer conveying direction]
First, a method of arranging the coaxial antenna according to the present modification in the raw material layer transport direction will be described with reference to FIG.

The time t during which the agglomerated material transported inside the drying furnace 5 is heated by the microwaves radiated from one coaxial antenna 123 according to this modification is the heating range (2 × δ) of the coaxial antenna 123. _eff ) is W (mm) and the agglomerated material transport speed is V [mm / sec], which is approximately (W / V) seconds.

  On the other hand, when a microwave is guided using a coaxial antenna, the diameter of the coaxial antenna is set to be small so that a plurality of propagation modes do not occur inside the antenna and the microwave transmission efficiency is maintained. Often accompanied by conditions related to the wavelength of the wave. As a result, it is difficult to set the diameter of the coaxial antenna 123 to an arbitrary size. Therefore, it is conceivable that the heating time t becomes a certain value.

  In order to sufficiently dry the agglomerate with microwaves during such a predetermined time, it is conceivable to use a microwave with a high output intensity as one of the measures. However, the agglomerates that exist around the coaxial antenna and are heated by microwaves are not necessarily heated uniformly because of differences in heating depending on the position of the agglomerates. In addition, when trying to obtain drying in a short time using a high-power microwave, some agglomerates may be overheated and the volatile components contained in the agglomerates may ignite. is there. Therefore, in order to sufficiently dry the agglomerate by microwave, the microwave is used so that the agglomerate does not overheat, and the microwave action time is lengthened to promote drying. It is important to plan.

  Therefore, in the present modification, for example, as shown in FIG. 24, the coaxial antenna 123 is arranged side by side in the conveyance direction of the raw material layer so that the heating range of the coaxial antenna 123 continues in the conveyance direction of the raw material layer. By adopting such an arrangement method of the coaxial antenna, it is possible to lengthen the section where the microwave is irradiated, and thus, it is possible to lengthen the action time of the microwave on the agglomerated material. .

  Here, the arrangement method of the coaxial antennas 123 in the transport direction is not particularly limited as long as the heating ranges of the coaxial antennas 123 adjacent to each other in the transport direction are continuous. They may be in contact or separated from each other. In addition, when arrange | positioning adjacent coaxial antenna 123 apart, it is preferable to provide a cover etc. so that an agglomerate may not block in the space between adjacent coaxial antennas 123. FIG.

  FIG. 24 illustrates the case where two coaxial antennas 123 are continuously arranged in the conveyance direction. However, three or more coaxial antennas 123 may be arranged continuously in the conveyance direction. Needless to say.

[Vibration relaxation mechanism]
Next, with reference to FIGS. 25A and 25B, a technique for mitigating vibration generated in the coaxial antenna 123 as the agglomerated material is conveyed will be described.

  In the microwave drying apparatus 10 according to the second embodiment of the present invention and its modification, the agglomerated material is stacked on a mesh conveyor to form a raw material layer, and then conveyed from the upper part to the lower part of the raw material layer. For the drying furnace that dries the agglomerate by passing hot air toward the same, insert the coaxial antenna 123 from above the drying furnace and irradiate the raw material layer lower layer with microwaves, and the corresponding part It is a device that promotes drying.

  At this time, the coaxial antenna 123 inserted from above the drying furnace 5 is subjected to a stress that varies as the agglomerated material is conveyed. The stress acting on the coaxial antenna fluctuates because the transport speed by the mesh conveyor is not constant but slightly fluctuates, and the density of the agglomerates is not strictly uniform, so the agglomeration contacting the coaxial antenna It is conceivable that the state of the chemical compound changes from moment to moment with the conveyance. When such fluctuating stress acts on the coaxial antenna 123, the coaxial antenna 123 is vibrated in the raw material layer conveyance direction. When considering long-term use of the coaxial antenna under such circumstances, there is a concern that such vibration may cause fatigue damage of the waveguide 111 and the coaxial antenna 123.

  Therefore, in the microwave drying apparatus 10 according to the present modification, a vibration mitigation mechanism for mitigating vibrations generated along with the transportation of the agglomerated material is installed in the waveguide 111 located on the upstream side of the converter 121. To do. Examples of such a vibration relaxation mechanism include the following two types of mechanisms.

  As a first vibration mitigation mechanism, a waveguide having a mechanism for mitigating vibration may be provided in the waveguide 111 that guides the microwave generated by the microwave oscillator 101.

  As a waveguide including a mechanism for reducing vibration, for example, a waveguide having a slide mechanism that enables sliding in the central axis direction of the waveguide (hereinafter referred to as a slide waveguide), or a microwave. For example, a waveguide having a bellows portion formed of a metal material capable of being guided (more preferably, a metal material similar to the waveguide) (hereinafter referred to as a flexible waveguide).

  Since the slide waveguide has a slide mechanism, it can expand and contract in the central axis direction of the waveguide, so that vibration substantially parallel to the central axis direction of the waveguide can be mitigated. In addition, since the flexible waveguide has a metal bellows portion, it can be bent in a direction substantially orthogonal to the central axis direction of the waveguide. On the other hand, it is possible to mitigate vibrations in a direction substantially perpendicular to the direction.

  Further, as the second vibration relaxation mechanism, an elastic member may be provided on a part of the support that supports the coaxial antenna 123 that is a microwave irradiation member. By providing an elastic member such as a spring mechanism or a rubber member on a part of the support, vibration generated in the coaxial antenna 123 supported by the support can be reduced by the elastic member.

  By providing the vibration mitigation mechanism as described above, it becomes possible to mitigate vibrations generated along with the transportation of the agglomerated material, and to prevent the waveguide 111 and the coaxial antenna 123 from being fatigued. it can.

  FIG. 25A shows that a flexible waveguide 161 is installed as a first vibration mitigating mechanism with respect to the waveguide 111 located on the upstream side of the converter 121, and one of the supports 163 is used as a second vibration mitigating mechanism. An example in which an elastic member 165 made of, for example, a spring mechanism is provided in the part is shown.

  In the example shown in FIG. 25A, the waveguide 111 extending from the microwave oscillation mechanism such as the microwave oscillator 101, the circulator 103, and the automatic matching unit 107 is located upstream of the converter 121. In addition, a flexible waveguide 161 is installed in a part of the waveguide extending in the vertical direction. As described above, the flexible waveguide 161 relieves vibration in a direction substantially perpendicular to the axial direction of the waveguide, and therefore is inserted into the drying furnace 5 as shown in FIG. 25A. Therefore, it is preferable to be installed in a part of the waveguide 111 provided in a substantially vertical direction.

  In FIG. 25A, an elastic member 165 including a spring mechanism is provided on a part of a support 163 that supports the coaxial antenna 123 and extends in the horizontal direction. The spring mechanism is a mechanism that relieves stress by expanding and contracting the spring in the direction of the central axis of the spring.

  As shown in FIG. 25A, the ends of the microwave oscillation mechanism and the support 163 are fixed to a strong member such as a wall. In addition, by installing the flexible waveguide 161 and the elastic member 165 as described above, the converter 121 and the coaxial antenna 123 positioned downstream of the flexible waveguide 161 and in front of the elastic member 165 are structured. Separated and can move freely to some extent. In addition, it is preferable to provide an embedding material 167 for maintaining the airtightness of the drying furnace 5 while allowing the coaxial antenna 123 to move to some extent while inserting the coaxial antenna 123 into the drying furnace 5.

  FIG. 25B shows an example in which a slide waveguide 169 is installed instead of the flexible waveguide 161 shown in FIG. 25A. As described above, the slide waveguide 169 relaxes vibrations in the axial direction of the waveguide. Therefore, as shown in FIG. 25B, the slide waveguide 169 extends in a substantially horizontal direction on the upstream side of the converter 121. It is preferable to be installed in a part of the waveguide 111.

  25A and 25B illustrate the case where one of the flexible waveguide 161 and the slide waveguide 169 is provided for one waveguide 111, the flexible waveguide 161 and the slide are illustrated. A waveguide 169 may be used in combination. 25A and 25B illustrate the case where one flexible waveguide 161, elastic member 165, and slide waveguide 169 are used, these members are illustrated as one waveguide 111 and coaxial antenna 123. A plurality of them may be installed.

  25A and 25B illustrate the case where the flexible waveguide 161 or the slide waveguide 169 and the elastic member 165 are used together, but depending on the agglomerated material transport speed, the elastic member Instead of using 165, only the flexible waveguide 161 or the slide waveguide 169 may be provided.

  In FIGS. 25A and 25B, the mechanism for structurally separating the coaxial antenna that receives the fluctuating stress has been described. However, the entire coaxial antenna 123 including the microwave oscillation mechanism is made movable to reduce vibration. It is also possible to do so.

  In the above, the modification of the microwave irradiation member which concerns on the 2nd reference form of this invention was demonstrated, referring FIGS. 24-25B.

(Third reference form)
The microwave drying apparatus 10 according to the first reference embodiment and the second reference embodiment of the present invention inserts the microwave irradiation member 109 from above the drying furnace 5 so that the lower layer portion of the raw material layer made of an agglomerated material. Was selectively heated. The microwave drying apparatus 10 according to the third embodiment of the present invention selectively inserts a slit antenna as a microwave irradiation member 109 from the side wall of the drying furnace 5 to selectively select a lower layer portion of the raw material layer made of agglomerated material. Heat to. Hereinafter, a microwave drying apparatus and a microwave drying method using a slit antenna as a microwave irradiation member will be described in detail with reference to FIGS. 26 to 31.

  In addition, since the whole structure of the microwave drying apparatus 10 which concerns on this reference form is the same as that of the microwave drying apparatus 10 which concerns on embodiment of this invention shown in FIG. 6, detailed description is abbreviate | omitted below. To do.

<Configuration of microwave irradiation member>
Below, the structure of the microwave irradiation member which concerns on this reference form is demonstrated in detail, referring FIGS. 26-31. 26 to 31 are explanatory views showing the microwave irradiation member according to the present embodiment.

  As shown in FIG. 26, in this embodiment, a slit antenna (also referred to as a slot antenna) 131 is used as the microwave irradiating member 109, and this slit antenna 131 is conveyed in the depth direction in FIG. It inserts into the raw material layer which consists of an agglomerated material from the side wall of the drying furnace 5 located in the immediate vicinity of a mesh conveyor. In FIG. 26, the slit antenna 131 is illustrated as being inserted so as to penetrate the drying furnace 5 in the width direction, but the end of the slit antenna 131 in the drying furnace width direction penetrates the drying furnace 5. You don't have to. Further, in FIG. 26, only one of the slit antennas 131 inserted into the drying furnace 5 is shown for easy understanding, but the drying furnace 5 includes a plurality of slit antennas 131. It is inserted from the side wall of the drying furnace 5.

  FIG. 27 is an explanatory diagram for explaining the configuration of the slit antenna 131 used as the microwave irradiation member 109. The figure shown in the upper part of FIG. 27 is a view when the slit antenna 131 is viewed from above, and the figure shown in the lower part of FIG. 27 is a cross section when the slit antenna 131 shown in the upper part is cut along the AA cutting line. Is schematically shown.

  As shown in FIG. 27, the slit antenna 131 according to the present embodiment has a rectangular metal tube and a plurality of openings (slits) 133 provided on the upper surface of the metal tube. The opening 133 is provided on the upper surface of the rectangular metal tube so that the distance between the openings 133 adjacent to each other corresponds to half the wavelength of the microwave propagating inside the metal tube. . The number of openings 133 provided in the metal tube may be appropriately determined according to the width of the drying furnace 5 and is not particularly limited. The shape and size of the opening 133 may be determined so as to have a shape and size capable of guiding a microwave having a desired frequency and intensity.

A terminal reflector (termination) 135 is provided at the end of the slit antenna 131 in the drying furnace width direction. The terminal reflector 135 is a member that totally reflects electromagnetic waves belonging to the microwave band. By finely adjusting the installation position of the end reflector 135 in the width direction of the drying furnace, the portion corresponding to the peak of the intensity distribution of the microwave propagating through the slit antenna 131 is adjusted to match the position of the opening 133. It can be performed. By performing such adjustment, the intensity of the microwave radiated from the opening 133 can be maximized.

  As shown in FIG. 26, the weight of the raw material layer made of agglomerated material is superimposed on the surface of the slit antenna 131 where the opening 133 is provided. Accordingly, the slit antenna 131 takes into consideration the load per unit surface received from the agglomerated material being transferred, so that the cross-sectional shape has a strength that prevents buckling deformation due to the load. It is manufactured using various metals such as (Al), nonmagnetic austenitic stainless steel (SUS), and alloys containing these.

  The inside of the raw material layer of the drying furnace 5 has a temperature of about 80 ° C. or higher at the lower layer portion and is in a high temperature and high humidity state having a humidity close to about 100%, and the agglomerated material is moving under such conditions. . Therefore, in order to prevent the occurrence of arcing due to moisture entering the inside of the slit antenna 131 and to prevent dust from entering the inside of the slit antenna 131, a protective gas such as dry air or dry nitrogen is applied to the slit antenna. It is preferable that the slit antenna 131 is introduced into the inside of 131 so that a positive pressure is applied.

  In order to protect the opening 133 of the slit antenna 131, it is preferable that a ceramic cover 137 is provided at least directly above the opening 133. The ceramic cover 137 preferably has the same plane projection size as the slit antenna 131 itself and covers the entire upper surface of the slit antenna 131 including the opening 133.

The ceramic cover 137 is made of inorganic material ceramics that absorb less microwaves as a heating source, can be used even in a high temperature and high humidity state, and have strength, wear resistance, and workability that can withstand contact with agglomerated materials. It is formed. The inorganic material ceramic used for the ceramic cover 137 preferably has a dielectric loss coefficient ε _r ″ relating to microwave absorption characteristics of less than 0.02. The dielectric loss coefficient ε _r ″ is less than 0.02. This makes it possible to suppress self-heating of the inorganic material ceramics due to microwave absorption.

Examples of such inorganic material ceramics include alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), sialon (SiAlON, chemical formula: Si ₃ N ₄ · Al ₂ O ₃ ), aluminum nitride (AlN), Examples include boron nitride (BN). The ceramic cover 137 may be manufactured using these inorganic material ceramics alone, or the ceramic cover 137 may be manufactured by mixing these inorganic material ceramics.

  In the present embodiment, as shown in FIG. 28, a plurality of such slit antennas 131 are arranged across the transport direction of the drying furnace so that the major axis direction of the slit antenna 131 is substantially parallel to the drying furnace width direction. . At this time, as shown in FIG. 28, each slit antenna 131 is inserted from the side wall of the drying furnace 5 so as to be positioned almost immediately above the mesh conveyor. As a result, the agglomerated material in the drying furnace 5 is transported so as to get over the slit antenna 131 and is heated by the microwave while getting over the slit antenna 131.

  Moreover, in this reference form, the slit antenna 131 is installed so that the heating range (namely, slit opening part) of the several slit antenna 131 whole covers substantially the whole width direction of the drying furnace 5. FIG.

  At this time, as shown in FIG. 28, the position of the opening 133 of the slit antenna 131 is shifted between the adjacent slit antennas 131 in the transport direction so as to complement each other's heating range. .

  When the openings of the plurality of slit antennas do not cover substantially the entire width of the drying furnace 5, the heating range of the microwave radiated from the slit antenna does not reach the entire width of the furnace, and agglomerates in the width direction of the furnace. Since uneven heating of the chemical conversion raw material is possible, it leads to uneven drying of the raw material, which is not preferable. However, since the drying of the raw material is improved in the portion heated by the microwave, the drying as an average value as the whole raw material is improved according to the number of the inserted waveguides.

  Also, if the efficiency of hot air drying in the furnace width direction is different as a characteristic of the drying furnace, the slit antenna opening is provided only in the portion where the drying efficiency is inferior and the drying of the agglomerated raw material is delayed, and microwave irradiation It is also effective to do.

  Further, how to arrange each slit antenna 131 is not particularly limited to the example shown in FIG. 28, and for example, this bias is based on the knowledge about the residual moisture unevenness in the drying furnace 5. The arrangement position of the slit antenna 131 may be determined so that the above can be eliminated.

  Here, FIG. 28 shows the case where the slit antenna 131 is arranged so that the major axis direction of the slit antenna 131 is substantially parallel to the width direction of the drying furnace 5, but as shown in FIG. 29, for example. The slit antenna 131 may be disposed obliquely. By performing such an arrangement, it is possible to further widen the range in the furnace width direction in which each slit antenna 131 can be heated, and it is possible to heat a wider range of agglomerates. 29 shows a case where the angle (tilt angle) formed between the major axis direction of the slit antenna 131 and the drying furnace width direction is constant, the tilt angles of the slit antennas 131 are different from each other. In addition, a slit antenna 131 may be provided.

  In order to make it easy for the agglomerated material conveyed in the drying furnace 5 to get over the slit antenna 131, for example, as shown in FIG. May be provided.

  Specifically, as shown in the upper part of FIG. 30, a tapered portion 139a whose height decreases toward the upstream side in the transport direction may be provided on the side surface of the slit antenna 131 on the upstream side in the transport direction. Good. Further, as shown in the lower part of FIG. 30, a tapered portion is provided on the side surface on the upstream side in the transport direction of the slit antenna 131 so that the height decreases toward the upstream side in the transport direction. Alternatively, a roller portion 139b may be provided. By providing such a tapered portion 139a or roller portion 139b, the agglomerated material can easily get over the slit antenna 131, and the conveyance resistance of the agglomerated material by the slit antenna 131 can be further reduced. Further, not only the upstream end portion of the slit antenna 131 in the transport direction but also the end portion on the downstream side in the transport direction may be provided with the tapered portion 139a or the roller portion 139b having a roller in the tapered portion.

  Further, as shown in FIG. 31, the slit antenna 131 may be disposed not only near the mesh conveyor but also above the mesh conveyor so as to be separated from the mesh conveyor surface. By disposing the slit antenna 131 vertically in the height direction of the drying furnace 5, various portions of the raw material layer conveyed in the drying furnace 5 can be heated by microwaves.

  The microwave drying apparatus 10 and the microwave drying method according to the third reference embodiment of the present invention have been described in detail above with reference to FIGS.

<Modification of third reference embodiment>
Next, a modification of the microwave irradiation member according to the third embodiment of the present invention will be described with reference to FIGS. 32A to 33B. FIGS. 32A to 33B are explanatory views for explaining a modification of the microwave irradiation member according to the third embodiment of the present invention.

[Method of disposing the slit antenna in the material layer conveying direction]
Next, with reference to FIGS. 32A and 32B, a method of arranging the slit antenna according to this modification in the raw material layer transport direction will be described.

  The time t during which the agglomerated material transported inside the drying furnace 5 is heated by the microwave irradiated from one slit antenna 131 according to this modification is the width of the slit antenna 131 (width in the transport direction). ) Is W [mm], and the agglomerated material transport speed is V [mm / sec], approximately (W / V) seconds.

  On the other hand, when a microwave is guided using a slit antenna, a microwave that guides the width of the slit antenna is used in order to prevent a plurality of propagation modes from occurring inside the slit antenna and to maintain the transmission efficiency of the microwave. It is often less than the wavelength of. For example, when a microwave of 2.45 GHz is used, the maximum width in the conveyance direction of the slit antenna is about 120 mm. Therefore, when the maximum width of one slit antenna is about 120 mm, the time t is extremely short considering the transport speed of a normal mesh conveyor.

  In order to sufficiently dry the agglomerate with microwaves in such a short time, it is conceivable to use microwaves with high output intensity as one of the measures. However, the agglomerates that are present above the slit antenna and are heated by the microwaves are not necessarily heated uniformly because of differences in heating depending on the position of the agglomerates. In addition, when trying to obtain drying in a short time using a high-power microwave, some agglomerates may be overheated and the volatile components contained in the agglomerates may ignite. is there. Therefore, in order to sufficiently dry the agglomerate by microwave, the microwave is used so that the agglomerate does not overheat, and the microwave action time is lengthened to promote drying. It is important to plan.

  Therefore, in this modification, for example, as shown in FIGS. 32A and 32B, the slit antenna 131 is arranged in the material layer transport direction so that the heating range of the slit antenna 131 is continuous in the material layer transport direction. To do. By adopting such an arrangement method of the slit antenna, it is possible to lengthen the section where the microwave is irradiated, and in turn, it is possible to lengthen the action time of the microwave on the agglomerated material. .

  Here, the arrangement method of the slit antennas 131 in the transport direction is not particularly limited as long as the heating ranges of the slit antennas 131 adjacent to each other in the transport direction are continuous. They may be in contact or separated from each other. In the case where the adjacent slit antennas 131 are spaced apart from each other, it is preferable to provide a cover or the like so that the space between the adjacent slit antennas 131 is not clogged.

  32A and 32B show the case where two slit antennas 131 are continuously arranged in the transport direction, but three or more slit antennas 131 are continuously arranged in the transport direction. Needless to say.

[Vibration relaxation mechanism]
Next, with reference to FIGS. 33A and 33B, a technique for mitigating vibrations that occur in the slit antenna 131 as the agglomerated material is conveyed will be described.

  In the microwave drying apparatus 10 according to the third embodiment of the present invention and its modification, the agglomerated material is stacked on a mesh conveyor to form a raw material layer, and then conveyed from the upper part to the lower part of the raw material layer. For the drying furnace that dries the agglomerate by passing hot air toward the slit, the slit antenna 131 is inserted from the side wall of the drying furnace and the lower layer portion of the raw material layer is irradiated with microwaves, so that the corresponding part It is a device that promotes drying.

  At this time, the slit antenna 131 inserted from the side wall of the drying furnace 5 is subjected to a stress that varies as the agglomerated material is conveyed. The reason why the stress acting on the slit antenna 131 fluctuates is that the conveyance speed by the mesh conveyor fluctuates slightly, and the density of the agglomerated material is not strictly uniform, so that it contacts the slit antenna 131. It is conceivable that the state of the agglomerated material changes from moment to moment with the conveyance. When such a fluctuating stress acts on the slit antenna 131, the slit antenna 131 will vibrate in the material layer transport direction. When considering long-term use of the slit antenna under such circumstances, there is a concern that such vibration may cause fatigue failure of the waveguide 111 and the slit antenna 131.

  Therefore, in the microwave drying apparatus 10 according to the present modification, a vibration mitigation mechanism that mitigates vibrations generated along with the transport of the agglomerated material is installed in the waveguide 111 connected to the slit antenna 131. . Examples of such a vibration relaxation mechanism include the following two types of mechanisms.

  As a first vibration mitigation mechanism, a waveguide having a mechanism for mitigating vibration may be provided in the waveguide 111 that guides the microwave generated by the microwave oscillator 101.

  As a waveguide including a mechanism for reducing vibration, for example, a waveguide having a slide mechanism that enables sliding in the central axis direction of the waveguide (hereinafter referred to as a slide waveguide), or a microwave. For example, a waveguide having a bellows portion formed of a metal material capable of being guided (more preferably, a metal material similar to the waveguide) (hereinafter referred to as a flexible waveguide).

  Since the slide waveguide has a slide mechanism, it can expand and contract in the central axis direction of the waveguide, so that vibration substantially parallel to the central axis direction of the waveguide can be mitigated. In addition, since the flexible waveguide has a metal bellows portion, it can be bent in a direction substantially orthogonal to the central axis direction of the waveguide. On the other hand, it is possible to mitigate vibration in a direction substantially orthogonal to the direction.

  In addition, as the second vibration relaxation mechanism, an elastic member may be provided on a part of the support that supports the slit antenna 131 that is a microwave irradiation member. By providing an elastic member such as a spring mechanism or a rubber member on a part of the support, vibration generated in the slit antenna 131 supported by the support can be reduced by the elastic member.

  By providing the vibration mitigating mechanism as described above, it is possible to mitigate vibrations generated along with the transportation of the agglomerated material, and to prevent the waveguide 111 and the slit antenna 131 from being fatigued. it can.

  FIG. 33A shows an example in which a flexible waveguide 161 is installed as a first vibration relaxation mechanism with respect to the waveguide 111.

  In the example shown in FIG. 33A, a part of the waveguide extending in the vertical direction among the waveguides 111 extending from the microwave oscillation mechanism such as the microwave oscillator 101, the circulator 103, and the automatic matching unit 107 is used. A flexible waveguide 161 is installed. As described above, the flexible waveguide 161 relieves vibration in a direction substantially orthogonal to the axial direction of the waveguide, and therefore is inserted into the drying furnace 5 as shown in FIG. 33A. Therefore, it is preferable to be installed in a part of the waveguide 111 provided in a substantially vertical direction.

  FIG. 33B shows an example in which a slide waveguide 169 is installed instead of the flexible waveguide 161 shown in FIG. 33A. FIG. 33B shows an example in which an elastic member 165 made of, for example, a spring mechanism is provided on a part of the support 163 as the second vibration relaxation mechanism.

  As described above, the slide waveguide 169 relieves vibrations in the axial direction of the waveguide. Therefore, as shown in FIG. 33B, one of the waveguides 111 extending in a substantially horizontal direction. It is preferable to be installed in the section.

  In FIG. 33B, an elastic member 165 including a spring mechanism is provided on a part of a support 163 that supports the slit antenna 131 and extends in the horizontal direction. The spring mechanism is a mechanism that relieves stress by expanding and contracting the spring in the direction of the central axis of the spring.

  As shown in FIGS. 33A and 33B, the ends of the microwave oscillation mechanism and the support 163 are fixed to a strong member such as a wall. In addition, by installing the flexible waveguide 161 or the slit waveguide 169 or the elastic member 165 as described above, the downstream side of the flexible waveguide 161 or the slit waveguide 169 and the front side of the elastic member 165. The slit antenna 131 located at is separated structurally and can move freely to some extent. In addition, it is preferable to provide an embedded material for maintaining the airtightness of the drying furnace 5 while allowing the slit antenna 131 to move to some extent while the slit antenna 131 is inserted into the drying furnace 5.

  33A and 33B illustrate the case where one of the flexible waveguide 161 and the slide waveguide 169 is provided for one waveguide 111, the flexible waveguide 161 and the slide are illustrated. A waveguide 169 may be used in combination. 33A and 33B illustrate the case where one flexible waveguide 161, elastic member 165, and slide waveguide 169 are used, these members are illustrated as one waveguide 111 and slit antenna 131. A plurality of them may be installed.

  In FIG. 33A, the support 163 and the elastic member 165 are not shown for convenience of illustration, but it goes without saying that the support 163 and the elastic member 165 may be used in addition to the flexible waveguide 161. Conversely, in FIG. 33B, the case where the slide waveguide 169 and the elastic member 165 are used together is shown, but depending on the agglomerated material transport speed and the like, the flexible guide may be used without using the elastic member 165. Only the wave tube 161 or the slide waveguide 169 may be provided.

  In FIGS. 33A and 33B, the mechanism for structurally separating the slit antenna that receives the fluctuating stress has been described. However, the entire slit antenna 131 including the microwave oscillation mechanism is made movable to reduce vibration. It is also possible to do so.

  In the above, the modification of the microwave irradiation member which concerns on the 3rd reference form of this invention was demonstrated, referring FIG. 32A-FIG. 33B.

(First embodiment)
In the first to third reference embodiments described above, the case where the waveguide 111, the coaxial antenna 123, or the slit antenna 131 is used as the microwave irradiation member 109 has been described. It is also possible to use the microwave irradiation member 109 in combination. Hereinafter, a first embodiment of the present invention in which different types of microwave irradiation members 109 are used in combination will be described with reference to FIGS. 34 to 37B.

  In addition, since the whole structure of the microwave drying apparatus 10 which concerns on this embodiment is the same as that of the microwave drying apparatus 10 which concerns on embodiment of this invention shown in FIG. 6, detailed description is abbreviate | omitted below. To do.

<Configuration of microwave irradiation member>
Below, the structure of the microwave irradiation member which concerns on this embodiment is demonstrated in detail, referring FIGS. 34-37B. 34 to 37B are explanatory views showing the microwave irradiation member according to the present embodiment.

34 and 35 are explanatory views showing an example of the microwave irradiation member 109 according to the present embodiment.
As shown in FIG. 34, as the microwave irradiation member 109 according to this embodiment, the waveguide 111 described in the first reference embodiment and the slit antenna 131 described in the third reference embodiment are used in combination. Is possible. As shown in FIG. 35, as the microwave irradiation member 109 according to this embodiment, the coaxial antenna 123 described in the second reference form and the slit antenna 131 described in the third reference form are used in combination. It is possible.

  The detailed configuration of the waveguide 111, the coaxial antenna 123, and the slit antenna 131 and the method of installing the slit antenna 131 in the drying furnace are the same as those in the reference embodiments described above and the modifications thereof, and thus have the same effects. Detailed description will be omitted below.

  Here, the arrangement position of the waveguide 111 or the coaxial antenna 123 and the slit antenna 131 is, for example, as shown in FIG. 36, the heating range of each irradiation member as a whole is the width direction of the drying furnace 5. At least one of the waveguide 111 or the coaxial antenna 123 and the slit antenna 131 are disposed so as to cover substantially the entire area.

  Further, how to arrange the waveguide 111, the coaxial antenna 123, and the slit antenna 131 is not limited to the case shown in FIG. 36, for example, and the residual moisture unevenness in the drying furnace 5, for example, Based on the knowledge and the like, the arrangement position of each irradiation member may be determined so that this bias can be eliminated. In addition, as shown in the modification of the first reference embodiment to the modification of the third reference embodiment, the heating range of the waveguide 111, the coaxial antenna 123, and the slit antenna 131 is continuous in the transport direction. These microwave irradiation members may be arranged side by side in the transport direction.

  36 shows a case where the waveguide 111 and the slit antenna 131 are used together, but three types of irradiation members of the waveguide 111, the coaxial antenna 123, and the slit antenna 131 may be used together.

  In the drying furnace 5 which is the object of the present invention, as described above, drying is mainly performed by hot air from above, so that the lower layer of the raw material layer made of an agglomerated material such as a laminated briquette tends to have moisture deficiency as drying failure. In the environment. Here, in the microwave irradiation to the lower layer portion of the raw material layer by the waveguide 111 or the coaxial antenna 123, as shown in FIGS. 37A and 37B, the microwave electric field near the exit of the waveguide 111 or the coaxial antenna 123 is changed. The intensity of the microwave electric field in the vicinity of the lowermost layer of the raw material layer is slightly lower than that in the vicinity of the exit. As a result, the agglomerate in the vicinity of the region A surrounded by the solid line in FIGS. 34 and 35 is likely to be heated, and the heating efficiency to the agglomerate located in the lowermost layer (near the region B surrounded by the dotted line) tends to decrease. It becomes.

  On the other hand, in the slit antenna 131, in FIG. 34 and FIG. 35, heating to the lowermost agglomerate (near the region B surrounded by the dotted line in FIG. 34 and FIG. 35) immediately above the slit that is the microwave outlet. Efficiency is maximized.

  Therefore, when the waveguide 111 or the coaxial antenna 123 is used alone, a sufficient number of the waveguides 111 or the coaxial antennas 123 in the portion indicated as “slightly reduced” in FIGS. 37A and 37B. Installation is required, but by combining the waveguide 111, the coaxial antenna 123, and the slit antenna 131, the heating range in the agglomerate laminating direction (the height direction of the drying furnace) is expanded, and in the laminating direction It is possible to improve the progress of drying by heating the agglomerated material in a wider range.

  Further, regarding the heating in the width direction of the drying furnace 5, the slit antenna 131 is configured so that the interval between the openings 133 that radiate microwaves is ½ of the in-tube wavelength of the microwaves propagating through the antenna. Is efficiently performed. In a waveguide that guides a microwave with a frequency of 2.45 GHz, for example, in the case of the WRI-22 waveguide of the EIAJ standard, the wavelength in the tube is 14.8 cm, and the interval between the slits is 7.4 cm. The interval between the openings 133 is about 7 cm at the shortest, and microwaves can be emitted at a relatively narrow interval. Therefore, when the slit antenna 131 is used, it is possible to uniformly heat a wide range in the width direction of the conveyor.

  Therefore, by using the slit antenna 131 in combination with the waveguide 111 and the coaxial antenna 123, the number of the waveguide 111 or the coaxial antenna 123 inserted into the raw material layer for heating the drying furnace 5 as a whole can be reduced. It becomes possible, and reduction of equipment cost can be realized.

  In this embodiment, by radiating microwaves inside the raw material layer (lower layer part), most of the radiated microwave energy is absorbed by the raw material around the radiation point and used for heating the raw material. Yes, it is a heating method with high energy efficiency of heating.

  The microwave drying apparatus 10 and the microwave drying method according to the first embodiment of the present invention have been described above with reference to FIGS. 34 to 37B.

  In the above description, the microwave irradiation member according to the first reference embodiment or the second reference embodiment and the microwave irradiation member according to the third reference embodiment are used in combination. In the form, the method of combining the microwave irradiation members is not limited to the above case. That is, the microwave irradiation member according to the modification of the first reference embodiment or the modification of the second reference embodiment and the microwave irradiation member according to the third reference embodiment may be combined, or the first You may combine the microwave irradiation member which concerns on a reference form or a 2nd reference form, and the microwave irradiation member which concerns on the modification of a 3rd reference form. Moreover, you may combine the microwave irradiation member which concerns on the modification of a 1st reference form or the modification of a 2nd reference form, and the microwave irradiation member which concerns on the modification of a 3rd reference form.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Microwave dryer 101 Microwave oscillator 103 Circulator 105 Isolator 107 Automatic matching device 109 Microwave irradiation member 111 Waveguide 113,125,137,153 Ceramic cover 115,127,139a Tapered part 121 Converter 123 Coaxial antenna 123a Central conductor 123b Outer peripheral conductor 123c Spacer 131 Slit antenna 133 Opening part 135 End reflector 139b Roller part 151 Notch part 155 Alignment pin 157 Branching plate 161 Flexible waveguide 163 Support body 165 Elastic member 167 Embedding material 169 Slide waveguide

Claims (27)

A microwave drying apparatus installed in a hot-air drying furnace that reduces moisture contained in the material to be dried by transporting the material to be dried by hot air when the material is conveyed by a conveyor. And
A microwave oscillator that oscillates a microwave used to dry the object to be dried;
A heating range in which the object to be dried is heated by the microwave is inserted into the inside of the object layer to be dried that is transported to a depth including the lowest layer of the object to be dried, and A plurality of waveguides for irradiating the microwave with the microwave;
A plurality of openings provided directly on the conveyor and having a plurality of openings on an upper surface of a waveguide for guiding the microwaves, and the microwaves are irradiated to the object to be dried from each of the plurality of openings. The slit antenna,
With
The heating range of each of the waveguides and the opening of the slit antenna are arranged at intervals so as to cover the entire furnace width direction of the drying furnace as a whole. , Microwave drying equipment. A microwave drying apparatus installed in a hot-air drying furnace that reduces moisture contained in the material to be dried by transporting the material to be dried by hot air when the material is conveyed by a conveyor. And
A microwave oscillator that oscillates a microwave used to dry the object to be dried;
A heating range in which the object to be dried is heated by the microwave is inserted into the inside of the object layer to be dried that is transported to a depth including the lowest layer of the object to be dried, and A plurality of coaxial antennas for irradiating the microwaves with respect to the dry matter;
A plurality of openings provided directly on the conveyor and having a plurality of openings on an upper surface of a waveguide for guiding the microwaves, and the microwaves are irradiated to the object to be dried from each of the plurality of openings. The slit antenna,
With
The heating range of each of the coaxial antennas and the opening of the slit antenna are arranged at intervals so as to cover the entire furnace width direction of the drying furnace as a whole. Microwave dryer. At least two of the plurality of waveguides or coaxial antennas are arranged at different positions in the furnace width direction of the drying furnace,
The microwave drying apparatus according to claim 1 or 2, wherein the positions of the waveguides or the coaxial antennas adjacent to each other in the furnace width direction are different from each other. Wherein the plurality of waveguides, and an end portion facing the front Kiko conveyors the waveguide when inserted into the material to be dried layer is in the open, to claim 1 or 3 The microwave drying apparatus as described. The plurality of waveguides are formed on the layer to be dried so that a separation distance between a front end portion of the waveguide and the conveyor is equal to or more than a quarter of a wavelength of the microwave in free space. The microwave drying apparatus according to claim 4, wherein the microwave drying apparatus is inserted. The plurality of waveguides are provided with a notch on at least a side surface that is parallel to the drying object layer transport direction of the drying furnace when the waveguide is inserted into the drying object layer. The microwave drying apparatus according to claim 1, wherein the microwave is irradiated from the cutout portion. The plurality of waveguides are inserted into the material layer to be dried so that an upper end of the cutout portion in a height direction of the material layer to be dried is equal to or less than a height of the material layer to be dried. The microwave drying apparatus according to claim 6. In the plurality of waveguides, a distance between an upper end in a height direction of the layer to be dried of the notch and the conveyor is equal to or more than a quarter of the wavelength of the microwave in free space. The microwave drying apparatus according to claim 6, wherein the microwave drying apparatus is inserted into the layer to be dried. The microwave according to any one of claims 1 to 8, wherein the slit antenna is disposed so that a perpendicular axis direction of the slit antenna is parallel to the drying furnace width direction. Drying equipment. The microwave according to any one of claims 1 to 8, wherein the slit antenna is disposed so that a perpendicular axis direction of the slit antenna is inclined with respect to the drying furnace width direction. Drying equipment. The waveguide has a rectangular cross-sectional shape perpendicular to the traveling direction of the microwave,
Short side of the rectangular front Kidan surfaces are perpendicular to the conveying direction, wherein the long side of the rectangular cross section is parallel to the transport direction, claim 1,3 The microwave drying apparatus of any one of 10-10. The coaxial antenna is
A central conductor which is a hollow or solid metal tube;
An outer peripheral conductor which is a hollow metal tube provided further outside the central conductor;
Have
The end portion of the center conductor on the object layer side is one fourth of the wavelength of the microwave propagated in the coaxial antenna than the end portion of the outer conductor on the object layer side. The microwave drying apparatus according to claim 2, wherein the microwave drying apparatus protrudes by a corresponding length. The center conductor and the outer peripheral conductor of the coaxial antenna are fixed to each other by a spacer formed of an inorganic material ceramic having a dielectric loss coefficient of less than 0.02. 12. The microwave drying apparatus according to 12. The tip or notch of the waveguide or the tip of the coaxial antenna and at least the opening of the slit antenna are formed of an inorganic material ceramic having a dielectric loss coefficient of less than 0.02. A microwave drying apparatus according to any one of claims 1 to 13, wherein a ceramic cover is provided. 15. A vibration mitigation mechanism for mitigating vibration generated with the conveyance of the object to be dried is provided for the waveguide or the coaxial antenna and the slit antenna. The microwave drying apparatus of any one of Claims. As the vibration relaxation mechanism, a slide waveguide having a slide mechanism that enables axial sliding between the waveguide, the coaxial antenna or the slit antenna, and the microwave oscillator, or The microwave drying apparatus according to claim 15, wherein at least one of the flexible waveguides having a metal bellows portion is disposed. 17. The micro of claim 15, wherein an elastic member is provided as a part of a support body that supports the waveguide or the coaxial antenna and the slit antenna as the vibration relaxation mechanism. Wave drying equipment. The waveguide or the coaxial antenna and the slit antenna are arranged side by side in the conveyance direction so that the heating range is continuous in the conveyance direction. The microwave drying apparatus as described in 2. The microwave drying apparatus according to claim 1, wherein the waveguide is branched so that the heating range is continuous in the transport direction. A dustproof gas is introduced into the waveguide or the coaxial antenna and the slit antenna, and a positive pressure is applied to the waveguide or the coaxial antenna and the slit antenna. The microwave drying apparatus according to any one of claims 1 to 19, wherein the microwave drying apparatus is configured. The end of the waveguide or the coaxial antenna on the upstream side in the transport direction is provided with a tapered portion in which the area of the cross section perpendicular to the transport direction becomes smaller toward the upstream side in the transport direction. The microwave drying apparatus of any one of Claims 1-20. The taper portion whose height decreases toward the upstream side in the transport direction is provided at an end of the slit antenna on the upstream side in the transport direction, according to any one of claims 1 to 21. Microwave drying equipment.   23. The microwave drying apparatus according to claim 22, wherein one or more rollers are further provided for the tapered portion of the slit antenna. Between the microwave oscillator and the plurality of waveguides or the plurality of coaxial antennas, the impedance of the microwave oscillated from the microwave oscillator and the microwave oscillation reflected in the drying furnace The microwave drying apparatus according to any one of claims 1 to 23, further comprising an automatic matching unit that performs matching with an impedance of the microwave toward the machine. The microwave drying apparatus according to claim 13 or 14 , wherein the inorganic material ceramic is selected from the group consisting of alumina, silicon nitride, sialon, aluminum nitride, boron nitride, and a mixture thereof. This is a microwave drying method implemented in a hot-air drying furnace that reduces moisture contained in the material to be dried by conveying the material to be dried with hot air when the material to be dried is conveyed by a conveyor. And
Oscillates a microwave used to dry the object to be dried;
A plurality of heating ranges in which the object to be dried is heated by the microwave are inserted to the depth including the lowermost layer of the object to be dried, with respect to the inside of the object to be dried composed of the object to be dried being conveyed. Each of the waveguides is provided directly above the conveyor and has a plurality of openings on the top surface of the waveguide that guides the microwave, and each of the plurality of openings is directed to the object to be dried. Irradiating the microwave to the layer to be dried from each of a plurality of slit antennas that irradiate the microwave,
The heating range of each of the waveguides and the opening of the slit antenna are arranged at intervals so as to cover the entire furnace width direction of the drying furnace as a whole. , Microwave drying method. This is a microwave drying method implemented in a hot-air drying furnace that reduces moisture contained in the material to be dried by conveying the material to be dried with hot air when the material to be dried is conveyed by a conveyor. And
Oscillates a microwave used to dry the object to be dried;
A plurality of heating ranges in which the object to be dried is heated by the microwave are inserted to the depth including the lowermost layer of the object to be dried, with respect to the inside of the object to be dried composed of the object to be dried being conveyed. Each of the coaxial antennas is provided directly above the conveyor and has a plurality of openings on the top surface of the waveguide that guides the microwave, and the plurality of openings are connected to the object to be dried from each of the plurality of openings. Irradiating the microwave to the layer to be dried from each of a plurality of slit antennas that irradiate microwaves,
The heating range of each of the coaxial antennas and the opening of the slit antenna are arranged at intervals so as to cover the entire furnace width direction of the drying furnace as a whole. Microwave drying method.

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