Drying device and drying method

Abstract

[Problem] Provided is a drying device and a drying method that convey a material to be processed by sliding it over an opening portion under a warm air atmosphere, and thus, the material to be processed smaller than an opening is caused to pass through the opening and is classified while being continuously dried by a collecting portion. [Solution] A drying device dries a material to be processed by warm air. The drying device includes: a screw blade; an opening portion that is arranged below the screw blade and has an opening; and a collecting portion arranged below the opening portion. Rotation of the screw blade conveys the material to be processed by sliding the material to be processed over the opening portion, and the material to be processed smaller than the opening is caused to pass through the opening and is classified by the collecting portion.

Description

TECHNICAL FIELD

[0001] The present invention relates to a drying device and a drying method that process a material to be processed to be dried through heating and simultaneously classify the material to be processed. More specifically, the present invention relates to a drying device and a drying method that process a material to be dried to be dried through heating using a hot wind or warm water obtained from a biomass boiler or a combined heat and power device of biomass and simultaneously classify the material to be dried, in particular, a drying device and a drying method that produce dried wood chips for biomass gasification power generation.BACKGROUND ART

[0002] In recent years, in order to prevent global warming or effectively utilize local resources, there has been spreading a biomass gasification power generation device that crushes woody biomass, such as thinned wood cut down in mountains and forests, into chips, uses the chips as a biomass fuel and pyrolyzes the chips under a reducing atmosphere to convert the chips into a combustible gas, and drives a gas engine with the combustible gas thus generated to rotate an electric generator, thereby generating electricity.

[0003] Most of such biomass gasification power generation devices can obtain 20% to 30% power generation efficiency despite the compact size and have a power generation capacity of approximately 20 kW to 400 kW (per device). The gasification power generation device is a cogeneration system using a gas engine, and generates warm water at approximately 80°C, which has a heat amount approximately 1.5 times to 2 times the amount of power generation, from waste heat simultaneously with power generation.

[0004] Unseasoned wood or the like used as this woody biomass fuel has a moisture content rate of 50% to 60%, and contains moisture. When a material with a high moisture content rate is used in the gasification power generation device, a heat decomposition temperature of a gasification furnace lowers, and liquid tar as an undecomposed component is generated. As a result, the operation of the gasification power generation device is disrupted, and therefore, gasification manufacturers specify using biomass fuel chips dried to have a moisture content rate of 10% to 15% or less as described in Non-Patent Document 1.

[0005] The biomass fuel chips are difficult to dry to approximately 20% or less, which is an equilibrium moisture content with the humidity in the atmosphere, even when the biomass fuel chips have been dried for several months through sun drying. Therefore, drying by a drying device is necessary in order to obtain the moisture content rate of 10% to 15% or less, which is appropriate for the gasification power generation device.

[0006] In a general manner, business operators that use the biomass gasification power generation devices purchase classified biomass fuel chips, install a drying device before the gasification power generation device, and dry the chips to have a moisture content rate of 10% to 15% or less using warm air using warm water obtained by a cogeneration system.

[0007] Large-sized biomass fuel chips disrupt conveyance in the gasification furnace of the gasification power generation device. On the contrary, those of an excessively small size quickly burn in the gasification furnace, which results in an abnormal temperature rise in the gasification furnace, and therefore, gasification power generation device manufacturers specify the size of chips in detail as described in Non-Patent Document 1.

[0008] Patent Document 1 discloses a rotary drying device that allows continuous drying by, while rotating a material to be dried input into a rotating cylindrical body, drying the material to be dried with warm air fed from a warm air duct.

[0009] Patent Document 2 discloses a configuration including a dryer that dries crushed biomass generated by a crushing machine and a classification machine 32 that classifies the biomass dried by this dryer.CITATION LISTPATENT LITERATURE

[0010] Patent Document 1: JP-A-2012-251699 Patent Document 2: Japanese Patent No. 6245436 NON-PATENT LITERATURE

[0011] Non-Patent Document 1: Volter 40 pamphlet Volter 40 pamphlet [online], VOLTER JAPAN Co., Ltd., [searched on February 13, 2023], Internet <URL: http: / / www.volter.jp / pdf / Volter40_pamphlet.pdf>DISCLOSURE OF THE INVENTIONPROBLEMS TO BE SOLVED BY THE INVENTION

[0012] Thus, the biomass fuel chips need to be dried using a drying device, but drying the biomass fuel chips with the drying device generates a large quantity of fine powder after the drying. In particular, the rotary drying device disclosed in Patent Document 1 processes the biomass fuel chips into fine powder with rotation, thereby having a problem of generating a large quantity of fine powder.

[0013] Therefore, although a power generation business operator purchases already-classified biomass fuel chips, it is necessary to further provide a sieving device and remove the fine powder after the biomass fuel chips are caused to pass through the drying device.

[0014] The present invention has been invented in consideration of the above-described circumstances, and an object of the present invention is to provide a drying device and a drying method that allow processing biomass fuel chips to be dried through heating and simultaneously classify the biomass fuel chips by sieving in the same device.SOLUTIONS TO THE PROBLEMS

[0015] A drying device according to a first invention dries a material to be processed by warm air. The drying device includes: a screw blade; an opening portion that is arranged below the screw blade and has an opening; and a collecting portion arranged below the opening portion. Rotation of the screw blade conveys the material to be processed by sliding the material to be processed over the opening portion, and the material to be processed smaller than the opening is caused to pass through the opening and is classified by the collecting portion.

[0016] In the drying device according to a second invention, which is in the first invention, the screw blade is provided with a stirring blade portion that stirs the material to be processed in at least one position or more.

[0017] In the drying device according to a third invention, which is in the first invention, the screw blade is a shaftless screw blade having no shaft member in a rotational center.

[0018] In the drying device according to a fourth invention, which is in any one of the first invention to the third invention, the opening portion includes a plurality of plate materials having an opening, and shifting a planar arrangement of the plate materials allows a size of the opening to be changed.

[0019] In the drying device according to a fifth invention, which is in any one of the first invention to the third invention, the collecting portion is provided with a collecting screw blade in a parallel direction to the screw blade.

[0020] In the drying device according to a sixth invention, which is in any one of the first invention to the third invention, an exhaust outlet is provided below the opening portion, and a dust collector that removes dust is provided after the exhaust outlet.

[0021] A drying method according to a seventh invention dries a material to be processed by warm air. The method comprises: a conveying step of conveying the material to be processed by rotation of a screw blade; a classifying step of classifying the material to be processed into a collecting portion through an opening portion arranged below the screw blade and having an opening; and a collecting step of collecting the material to be processed from the collecting portion arranged below the opening portion. The classifying step conveys the material to be processed by sliding the material to be processed over the opening portion, and the material to be processed smaller than the opening is caused to pass through the opening and is classified by the collecting portion.EFFECTS OF THE INVENTION

[0022] In the present invention configured as described above, the material to be processed is conveyed by being slid over the opening portion under a warm air atmosphere by the rotation of the screw blade, and thus, the material to be processed smaller than the opening is caused to pass through the opening and is allowed to be classified while being continuously dried by the collecting portion.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Fig. 1(a) is a front cross-sectional view illustrating an exemplary drying device according to a first embodiment. Fig. 1(b) is a left side cross-sectional view illustrating the exemplary drying device according to the first embodiment. Fig. 2(a) is a perspective view illustrating an exemplary screw blade having a shaft member. Fig. 2(b) is a perspective view illustrating an exemplary screw blade having no shaft member. Fig. 2(c) is a perspective view illustrating an exemplary screw blade provided with a stirring blade portion. Fig. 3 is a perspective view illustrating an exemplary blade and opening portion. Fig. 4(a) is a plan view illustrating openings by circular-hole punching. Fig. 4(b) is a plan view illustrating openings by plain weaving. Fig. 4(c) is a perspective view illustrating openings by wedge wires. Fig. 5(a) is a left side cross-sectional view illustrating an exemplary drying device according to a second embodiment. Fig. 5(b) is a front cross-sectional view illustrating the exemplary drying device according to the second embodiment. Fig. 5(c) is a right side cross-sectional view illustrating the exemplary drying device according to the second embodiment. DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] The following describes a drying device and a drying method to which the present invention is applied in detail with reference to the drawings.

[0025] Fig. 1(a) is a front cross-sectional view illustrating an exemplary drying device 1 according to a first embodiment, and Fig. 1(b) is a left side cross-sectional view illustrating the exemplary drying device 1 according to the first embodiment.

[0026] The drying device 1 includes a drying chamber 21, a warm air generator 22 placed on the top of the drying chamber 21, and an exhaust outlet 23 placed on a side surface of the drying chamber 21.

[0027] The drying device 1 includes a screw blade 31 arranged in a horizontal orientation, an opening portion 41 that is arranged below the screw blade 31 and has an opening, and a collecting portion 5 arranged below the opening portion 41. The screw blade 31 is provided with a motor 32 on one end side, and provided with a bearing 33 on the other end side.

[0028] The collecting portion 5 includes a collecting screw blade 61, and a collecting casing 71 arranged below the collecting screw blade 61. The collecting screw blade 61 is provided with a collecting motor 62 on one end side, and provided with a collecting bearing 63 on the other end side.

[0029] The exhaust outlet 23 is arranged below the opening portion 41. The exhaust outlet 23 is connected to a cyclone dust collector 27. The cyclone dust collector 27 is connected to an exhaust fan 28.

[0030] An example of the screw blade 31 is illustrated in Fig. 2(a). This screw blade 31 is formed by arranging a spiral blade 312 around a rotary shaft 311. Another example of the screw blade 31 is illustrated in Fig. 2(b). This screw blade 31 is formed by the spiral blade 312, but is a shaftless screw blade having no shaft member in a space of a rotational center. By thus being shaftless, the screw blade 31 can have a hollow in a region of the rotary shaft, thereby allowing warm air to pass therethrough. Thus, drying efficiency with respect to a material to be processed can be increased.

[0031] Another example in which a stirring blade 313 is further provided for the screw blade 31 is illustrated in Fig. 2(c). The stirring blade 313 is a blade provided in at least one position or more on the blade 312 to stir the material to be processed. For example, the stirring blade 313 is a metal bar of stainless steel, and the stirring blade 313 is bonded to the blade 312 by metal welding. Such a configuration allows the conveyed material to be processed to be stirred and turned over by the rotation of the screw blade 31. This allows the screw blade 31 to invert a side with a high moisture content of the material to be processed to accelerate drying. Here, the stirring blade 313 only needs to be in a shape that can lift and turn over the material to be processed, and any shape is allowed as long as the blade 312 is provided with a hook portion.

[0032] In Fig. 1(b), while the screw blade 31 has three blades of a screw blade 31a (31), a screw blade 31b (31), and a screw blade 31c (31), the screw blade 31 may have four blades or six blades, or the screw blade 31 may have one blade to make the drying device compact.

[0033] Fig. 3 is a perspective view illustrating an example of the blade 312 and the opening portion 41. The motor 32 is connected to the blade 312. The opening portion 41 is arranged below the blade 312. The opening portion 41 is, for example, a screen having openings by circular-hole punching. In Fig. 3, the screen arranged below the blade 312 and having the openings is arranged not only below the blade 312 but also on sides, but the opening portion 41 only needs to be arranged below the blade 312, and the openings on the sides of the blade 312 are not necessary.

[0034] Fig. 4 is examples of the opening portion 41. Fig. 4(a) is a perspective view illustrating the screen by circular-hole punching. The screen by circular-hole punching is manufactured, for example, by punching a stainless steel plate material. Fig. 4(b) is a perspective view illustrating a screen by plain weaving. The screen by plain weaving is manufactured, for example, by plain weaving metal wires vertically and horizontally. Fig. 4(c) is a perspective view illustrating a screen by wedge wires. The wedge wires are a screen that is resistant to clogging by arranging wires having a cross-sectional shape of inverted triangles at equal intervals to form slits. The inverted triangle shape causes the slits to form inverse tapered shapes, and when the material to be processed falls down after passing between the slits, clogging is less likely to occur, and therefore, maintainability is high. The screen by the wedge wires is manufactured, for example, by combining stainless steel wires.

[0035] The opening portion 41 may be constituted by stacking a plurality of plate materials that have openings, and shifting the planar arrangement of the plate materials may allow the size of the openings to be changed. Such a configuration allows changing the size for classification of the material to be processed. Furthermore, the opening portion 41 may have a configuration in which the size of the openings is changed in a rotary shaft direction of the screw blade 31. The opening portion 41 may have a configuration in which, for example, the opening portion 41 has small openings in a region close to an input port 24, and large openings in a region close to an upper outlet 25.

[0036] While the embodiment described above has a configuration in which the opening portion 41 is arranged below the screw blade 31 and the collecting portion 5 is arranged below the opening portion 41, multiple stages of classification may be enabled by repeating two stages or more of one set of the screw blade 31 and the opening portion 41 arranged below the screw blade 31.

[0037] Fig. 5(a) is a left side cross-sectional view illustrating one example of the drying device 1 according to a second embodiment, Fig. 5(b) is a front cross-sectional view illustrating the example of the drying device 1 according to the second embodiment, and Fig. 5( c) is a right side cross-sectional view illustrating the example of the drying device 1 according to the second embodiment. Hereinafter, in the second embodiment, the same reference numerals are attached to the same components and members as those in the first embodiment described above, and thus, their descriptions are omitted below.

[0038] As illustrated in Fig. 5(b), the drying device 1 according to the second embodiment is connected to a feeding machine 8.

[0039] The feeding machine 8 includes an opening and closing door 84 placed on the top of the feeding machine 8, a raw material storage 86, and a feeding screw blade 81 arranged in a horizontal orientation.

[0040] The feeding screw blade 81 is connected to the screw blade 31 via a feeding rotary valve 85. The screw blade 31 is connected to the upper outlet 25 via an upper outlet rotary valve 251.

[0041] The collecting screw blade 61 is connected to a lower outlet 26 via a lower outlet rotary valve 261.

[0042] Next, the operation of the drying device 1 according to the first embodiment will be described.

[0043] The material to be processed is input via the input port 24, and thereafter is conveyed by the screw blade 31. The material to be processed is exposed to warm air generated from the warm air generator 22 in this conveyance process, thereby accelerating drying.

[0044] The material to be processed is conveyed by being slid over the opening portion 41 by the rotation of the screw blade 31. Only the material to be processed smaller than the openings of the opening portion 41 falls down in the openings, and moves to the collecting portion 5.

[0045] The material to be processed that has been conveyed without falling down in the openings of the opening portion 41 is taken out from the upper outlet 25.

[0046] The material to be processed that has moved to the collecting portion 5 is conveyed by the rotation of the collecting screw blade 61 arranged in the collecting portion 5 in a parallel direction to the screw blade 31, and is taken out from the lower outlet 26. That is, the material to be processed can be classified.

[0047] Warm air accelerates the drying of the material to be processed that has passed through the openings of the opening portion 41 and fallen down also when it is conveyed by the collecting screw blade 61.

[0048] By reducing the rotation speed of the screw blade 31, the material to be processed can be left to stand for a long period of time in the warm air in the drying chamber 21. Thus, the drying can be accelerated. Increasing the length in the axial direction of the screw blade 31 allows an increased amount of the material to be processed dried while being conveyed by the screw blade 31.

[0049] Here, while the rotation speeds of the screw blade 31 and the collecting screw blade 61 may be the same, adjustment may be performed in accordance with the amount of the material to be processed after the classification to set the rotation speeds of the screw blade 31 and the collecting screw blade 61 to be different.

[0050] The opening portion 41 having a configuration in which the openings are small in the region close to the input port 24 and the openings are large in the region close to the upper outlet 25 makes it difficult for the material to be processed to fall down through the openings immediately after the input, therefore, the material to be processed is more likely to be exposed to the warm air by the warm air generator 22, and thus, the drying can be accelerated.

[0051] Furthermore, in the configuration in which two stages or more of one set of the screw blade 31 and the opening portion 41 arranged below the screw blade 31 are repeated, setting the size of the openings of the opening portion to be different in each stage enables the multiple stages of classification.

[0052] The warm air used for drying includes fine powder generated from wood chips or the like. Therefore, the exhaust outlet 23 that removes dust is provided below the opening portion 41, and the cyclone dust collector 27 and the exhaust fan 28 that remove dust are arranged after the exhaust outlet, thereby removing dust, and thus, the fine powder is collectable from the cyclone dust collector 27. A gas that does not include the fine powder after the dust removal is dissipated into the atmosphere by the exhaust fan 28. Here, the fine powder collected from the cyclone dust collector 27 can be used again as livestock bedding or an extending agent of a plastic resin.

[0053] Thus, in the present invention, the material to be processed is conveyed by being slid over the opening portion 41 in a warm air atmosphere by the rotation of the screw blade 31, and thus, the material to be processed smaller than the openings of the opening portion 41 is caused to pass through the openings and collected by the collecting portion 5, thereby allowing the material to be processed to be classified while being continuously dried.

[0054] Next, the operation of the drying device 1 according to the second embodiment will be described.

[0055] The material to be processed is input into the raw material storage 86 from the opening and closing door 84. Tightening the open and close door 84 isolates the material to be processed from the external air and stores the material to be processed.

[0056] The feeding screw blade 81 is driven by a feeding motor 82 and rotates. The material to be processed stored in the raw material storage 86 is fed to the feeding screw blade 81, and conveyed by rotary driving of the feeding screw blade 81 based on the feeding motor 82.

[0057] The material to be processed conveyed by the rotation of the feeding screw blade 81 is fed to the screw blade 31 of the drying device 1 via the feeding rotary valve 85. Thus, passing through the feeding rotary valve 85 does not cause the warm air in the drying chamber 21 to return to the feeding machine 8, thereby allowing a stabilized temperature in the drying chamber 21.

[0058] The material to be processed conveyed without falling down in the openings of the opening portion 41 is taken out from the upper outlet 25 via the upper outlet rotary valve 251.

[0059] The material to be processed conveyed by the rotation of the collecting screw blade 61 is taken out from the lower outlet 26 via the lower outlet rotary valve 261.

[0060] Thus, taking out via the upper outlet rotary valve 251 and the lower outlet rotary valve 261 does not cause the warm air in the drying chamber 21 to be discharged into the external air, thereby allowing a stabilized temperature in the drying chamber 21.

[0061] Thus, the drying device 1 according to the second embodiment allows the material to be processed stored in the raw material storage 86 to be classified while being continuously dried.

[0062] The drying method according to the present invention has a conveying step of conveying the material to be processed by the rotation of the screw blade 31. The drying method conveys the material to be processed by sliding the material to be processed over the opening portion 41 in this conveying step, and thus passes the material to be processed smaller than the openings through the openings and classifies it with the collecting portion 5. The drying method has a classifying step of classifying the material to be processed into the collecting portion by the opening portion 41 arranged below the screw blade 31 and having the openings. The drying method has a collecting step of collecting the classified material to be processed from the collecting portion 5 arranged below the opening portion 41. Thus, the drying method according to the present invention allows the material to be processed to be classified while being continuously dried.

[0063] While in the embodiments of the present invention, biomass fuel chips, such as wood chips, have been presented as an example of the material to be processed, the material to be processed is not limited to the biomass fuel chips, and the embodiments of the present invention are applicable to drying and classifying a material obtained by pulverizing plastic or the like.

[0064] While the embodiments of the present invention have been described, the embodiments have been presented as examples, and are not intended to limit the scope of the invention. These novel embodiments can be embodied in a variety of other configurations. Various omissions, substitutions, and changes can be made without departing from the gist of the invention. The embodiments and the modifications thereof are within the scope and the gist of the invention and within the scope of the inventions described in the claims and their equivalents.DESCRIPTION OF REFERENCE SIGNS

[0065] 1:Drying device 21:Drying chamber 22:Hot air generator 23:Exhaust outlet 24:Input port 25:Upper outlet 251:Upper outlet rotary valve 26:Lower outlet 261:Lower outlet rotary valve 27:Cyclone dust collector 28:Exhaust fan 31:Screw blade 311:Rotary shaft 312:Blade 313:Stirring blade 32:Motor 33:Bearing 41:Opening portion 5:Collecting portion 61:Collecting screw blade 62:Collecting motor 63:Collecting bearing 71:Collecting casing 8:Feeding machine 81:Feeding screw blade 82:Feeding motor 83:Feeding bearing 84:Opening and closing door 85:Feeding rotary valve 86:Raw material storage

Claims

1. A drying device that dries a material to be processed by warm air, the drying device comprising: a screw blade; an opening portion that is arranged below the screw blade and has an opening; and a collecting portion arranged below the opening portion, wherein rotation of the screw blade conveys the material to be processed by sliding the material to be processed over the opening portion, and the material to be processed smaller than the opening is caused to pass through the opening and is classified by the collecting portion.

2. The drying device according to claim 1, wherein the screw blade is provided with a stirring blade portion that stirs the material to be processed in at least one position or more.

3. The drying device according to claim 1, wherein the screw blade is a shaftless screw blade having no shaft member in a rotational center.

4. The drying device according to any one of claims 1 to 3, wherein the opening portion includes a plurality of plate materials having an opening, and shifting a planar arrangement of the plate materials allows a size of the opening to be changed.

5. The drying device according to any one of claims 1 to 3, wherein the collecting portion is provided with a collecting screw blade in a parallel direction to the screw blade.

6. The drying device according to any one of claims 1 to 3, wherein an exhaust outlet is provided below the opening portion, and a dust collector that removes dust is provided after the exhaust outlet.

7. A drying method that dries a material to be processed by warm air, the method comprising: a conveying step of conveying the material to be processed by rotation of a screw blade; a classifying step of classifying the material to be processed into a collecting portion through an opening portion arranged below the screw blade and having an opening; and a collecting step of collecting the material to be processed from the collecting portion arranged below the opening portion, wherein the classifying step conveys the material to be processed by sliding the material to be processed over the opening portion, and the material to be processed smaller than the opening is caused to pass through the opening and is classified by the collecting portion.

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