Carbonization furnace

Abstract

To ignite biomass without the use of fossil fuels.SOLUTION: The carbonization furnace 100 comprises a furnace body 1, a hot blast unit 2, and a stirring unit 4. The furnace body 1 contains biomass B. The hot blast unit 2 is provided on one side of the furnace body 1 to send hot blast into the furnace body 1. The stirring unit 4 stirs the biomass B in the furnace body 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a carbonization furnace. [Background technology]

[0002] Conventionally, there is known a carbonization device for carbonizing a biomass fuel such as rice husk. For example, in Patent Document 1, rice husk is ignited and carbonized by an ignition burner.

[0003] Biochar, which is made by carbonizing biomass fuel, is useful as a soil conditioner. Furthermore, when biochar is stored underground in farmland, it is considered to have reduced or absorbed greenhouse gas emissions (see the J-Credit Scheme certified by the Japanese government). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-071712 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a burner is used as in Patent Document 1, the burner generates greenhouse gases such as carbon dioxide by consuming fossil fuels (diesel, kerosene, etc.). Therefore, even if biochar is stored underground, the effect of reducing greenhouse gas emissions is weakened, and there is a risk that the effect may be offset.

[0006] In view of the above circumstances, an object of the present invention is to ignite biomass without using fossil fuels. [Means for solving the problem]

[0007] In order to achieve the above-mentioned objective, a carbonization furnace according to one embodiment of the present invention is configured to comprise a furnace body for accommodating biomass, a hot air unit provided on the side of the furnace body for sending hot air into the furnace body, and a stirring unit for stirring the biomass in the furnace body.

[0008] Further features and advantages of the present invention will become apparent from the following embodiments. Effect of the Invention

[0009] According to the present invention, biomass can be ignited without using fossil fuels. [Brief description of the drawings]

[0010] [Figure 1] Schematic diagram showing an example of the configuration of a carbonization device [Diagram 2] Schematic diagram showing an example of the carbonization furnace configuration [Figure 3A] Cross-sectional view showing a modified example of the outer end shape of the stirring blade [Figure 3B] A top view showing another modified example of the outer end shape of the stirring blade. [Figure 4] A flowchart for explaining an example of a biomass ignition process using a hot air unit and a first temperature rise control process for a furnace body. [Diagram 5] A flowchart for explaining an example of a second temperature rise control process of the furnace body by combustion of biomass itself [Figure 6] Time chart showing an example of charcoal production in a carbonizer DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] In this specification, unless otherwise specified, the direction in which the central axis Jc, which will be described later, extends is referred to as the "vertical direction." Furthermore, the direction perpendicular to the central axis Jc is referred to as the "radial direction," and the direction of rotation about the central axis Jc is referred to as the "circumferential direction." Furthermore, within the radial direction, the direction approaching the central axis Jc is referred to as the "radial inward direction," and the direction away from the central axis Jc is referred to as the "radial outward direction."

[0013] <1. Carbonization device 500> FIG. 1 is a schematic diagram showing a configuration example of a carbonization apparatus 500. The carbonization apparatus 500 produces smoky charcoal C such as biochar from biomass B, and transports the smoky charcoal C to a bag 401 and packs it in the bag. The biomass B is an organic resource derived from a living organism, excluding fossil resources. In this embodiment, rice husks are used as the biomass B. However, the present invention is not limited to this example, and the biomass B may be an organic resource other than rice husk, for example, straw or wood. Biochar is a solid (carbonized material) produced by heating biomass at a temperature of more than 350° C. under an oxygen concentration controlled to a level at which it does not burn. In FIG. 1, the rough dashed line fa indicates the upper surface of the sedimentary layer of the biomass B in the ignition control of the biomass B and the first temperature rise control process in the furnace body 1, which will be described later. The solid line fb indicates the upper surface of the sedimentary layer of the biomass B (or smoky charcoal C) in the second temperature rise control and steady operation process in the furnace body 1, which will be described later.

[0014] As shown in FIG. 1, the carbonization apparatus 500 includes a carbonization furnace 100, a fuel supply device 200, a charcoal transport device 300, and a filling device 400. The carbonization furnace 100 ignites and burns biomass B with hot air exceeding 350° C. to produce smoky charcoal C. The fuel supply device 200 stores biomass B and supplies it to the carbonization furnace 100 as appropriate. The charcoal transport device 300 is, for example, a transport conveyor, and transports the smoky charcoal C discharged from the carbonization furnace 100 to the filling device 400. The smoky charcoal C transported by the charcoal transport device 300 is filled into a bag 401 by the filling device 400. The bag 401 is an example of a storage container for storing the smoky charcoal C.

[0015] The carbonization device 500 further includes a water sprinkler 402 capable of sprinkling water on the charcoal C. When a sensor (not shown) detects the burning or smoking of the charcoal C, the water sprinkler 402 sprinkles water on the charcoal C to prevent ignition of the charcoal C. The sensor may be, for example, a gas sensor that detects gas, smoke, etc. generated from the charcoal C, or an infrared sensor that detects the temperature distribution of the charcoal C in the bag 401. Alternatively, a thermocouple, a thermistor, etc. may be disposed in the bag 401 to detect the temperature of the filled charcoal C. In this embodiment, the water sprinkler 402 is disposed in the filling device 400. However, the present invention is not limited to this example, and the water sprinkler 402 may be disposed in the charcoal conveying device 300 together with the above-mentioned sensor.

[0016] In this embodiment, the gas generated during the production of the smoky charcoal C is exhausted to the outside of the carbonization furnace 100 through a flue 15 described later. However, without being limited to this example, the carbonization apparatus 500 may further include equipment for extracting or inducing a combustible gas (hydrogen, methane, carbon monoxide, etc.) from the gas and generating electricity using the combustible gas.

[0017] <2. Carbonization furnace 100> Next, a configuration example of the carbonization furnace 100 will be described with reference to Fig. 1 and Fig. 2. Fig. 2 is a schematic diagram showing a configuration example of the carbonization furnace 100. Fig. 2 is a plan view of the carbonization furnace 100 viewed downward from the dashed line II-II in Fig. 1. In Fig. 2, the deposition layer of biomass B (and smoky charcoal C) is shown transparently.

[0018] As shown in FIGS. 1 and 2, the carbonization furnace 100 includes a furnace body 1, a hot air unit 2, a fuel supply unit 3, an agitation unit 4, a temperature sensor 5, an upper temperature sensor 6, and a control device 7.

[0019] <2-1. Furnace body 1> The furnace body 1 is a heat-resistant container for burning the biomass B, and accommodates the biomass B. The furnace body 1 has a cylindrical portion 11, a lid portion 12, a bottom portion 13, a rotary valve 14, and a flue 15.

[0020] The tubular portion 11 is tubular and surrounds a central axis Jc extending in the vertical direction. At least the lower portion of the tubular portion 11 is cylindrical and centered on the central axis Jc. A hot air port 111, a supply port 112, a lower air supply port 113, and an upper air supply port 114 are arranged on the inner surface of the tubular portion 11 of the furnace body 1. These penetrate the tubular portion 11 in the radial direction. The carbonization furnace 100 further includes an air supply section 115.

[0021] The hot air unit 2 is connected to the hot air outlet 111. The hot air outlet 111 is an inlet for allowing hot air sent out from the hot air unit 2 to flow into the inside of the furnace body 1, and is arranged at the bottom of the tube part 11. In this embodiment, there are two hot air outlets 111, arranged in the circumferential direction, as shown in FIG. 2. Also, a different hot air unit 2 is connected to each hot air outlet 111. However, this is not limited to the example, and the hot air outlet 111 (and hot air unit 2) may be a single one, or three or more. Also, the vertical positions of the multiple hot air outlets 111 (and hot air units 2) may all be the same, or may be different from each other.

[0022] The fuel supply unit 3 is connected to the supply port 112. The supply port 112 is a fuel inlet for supplying the fuel (i.e., biomass B) transported by the fuel supply unit 3 into the inside of the furnace body 1, and is disposed above the hot air port 111.

[0023] An air supply unit 115 such as a compressor is connected to the lower air supply port 113 and the upper air supply port 114 via valves 1131 and 1141. The air supply unit 115 is controlled by the control device 7 and supplies air to the inside of the furnace body 1. Different air supply units 115 may be connected to the lower air supply port 113 and the upper air supply port 114, respectively, or the same air supply unit 115 may be connected to them. The valve 1131 switches between opening and closing the air supply passage between the air supply unit 115 and the lower air supply port 113 according to the control of the control device 7. The valve 1141 switches between opening and closing the air supply passage between the air supply unit 115 and the upper air supply port 114 according to the control of the control device 7.

[0024] The lower air inlet 113 is located at the bottom of the furnace body 1 (particularly the tube portion 11), and is disposed above the hot air outlet 111 and below the supply port 112. Within the furnace body 1, the space in which the biomass B is accommodated in the vertical direction and the space directly above it are low-oxygen regions where the oxygen concentration is low enough to prevent the biomass B from burning excessively, in order to turn the charcoal C into biochar. The air supplied by the air supply section 115 flows into the lower part of the furnace body 1 (i.e., the low-oxygen region) through the lower air inlet 113. That is, the lower air inlet 113 supplies gas with an appropriate amount of oxygen to the low-oxygen region.

[0025] Moreover, the upper air inlet 114 is disposed above the supply port 112. The space above the low oxygen region of the furnace body 1 (for example, the upper part) is filled with an ascending air current of gas generated by the combustion of the biomass B and heated air. These include combustible fine particles such as graphite and combustible gases. The space above the low oxygen region of the furnace body 1 is a high oxygen region with a high oxygen concentration because these are burned according to the furnace temperature. The air supplied by the air supply section 115 flows into the furnace body 1 (for example, the high oxygen region) through the upper air inlet 114. The upper air inlet 114 supplies gas with an appropriate amount of oxygen to the high oxygen region.

[0026] Next, the cover portion 12 spreads radially inward from the upper end of the tube portion 11 and covers the upper end of the tube portion 11 (i.e., the opening facing upward). An exhaust port 121 is arranged in the cover portion 12. The exhaust port 121 penetrates the cover portion 12 in the vertical direction. Note that, without being limited to this example, the exhaust port 121 may be arranged in the tube portion 11 and penetrate the tube portion 11 in the radial direction. By exhausting at least a part of the ascending air current in the furnace body 1 from the exhaust port 121, the increase in the internal pressure of the furnace body 1 can be suppressed. In addition, the ascending air current also contains gas generated by the combustion of the biomass B. Therefore, exhaust gas containing reusable gas (for example, combustible gas such as hydrogen, methane, carbon monoxide, etc.) can also be taken out from the exhaust port 121.

[0027] The bottom 13 spreads radially inward from the lower end of the tube part 11 and covers the lower end of the tube part 11 (i.e., the opening facing downward). The bottom 13 is provided with a central opening 131 and a discharge port 132. The central opening 131 and the discharge port 132 each penetrate the bottom 13 in the vertical direction. The central opening 131 is formed in the center of the bottom 13 when viewed from the vertical direction. The central axis Jc passes through the center of the central opening 131. The discharge port 132 is a through hole for discharging the smoked charcoal C to the outside of the furnace body 1. Preferably, the discharge port 132 is formed in the same direction as the rotation direction of the stirring unit 4 in the circumferential direction, at a position circumferentially away from the hot air port 111 and the supply port 112 when viewed from the vertical direction. In this way, it is possible to suppress the biomass B that is not sufficiently carbonized from being discharged from the discharge port 132.

[0028] The rotary valve 14 is connected to the discharge port 132, and changes the discharge speed of the contents (biomass B or charcoal C) in the furnace body 1 according to the control of the control device 7. The rotor of the rotary valve 14 stops rotating to prevent the discharge of biomass B (or charcoal C) from the discharge port 132. The rotor of the rotary valve 14 also discharges charcoal C from the discharge port 132 at a discharge speed according to the rotation speed of the rotor. A charcoal conveying device 300 is disposed directly below the discharge port 132. The charcoal C discharged from the discharge port 132 is conveyed by the charcoal conveying device 300 to the filling device 400, where it is stored in a bag 401.

[0029] The flue 15 is a cylindrical body connected to the exhaust port 121, and guides the exhaust gas discharged from the exhaust port 121. The flue 15 may be omitted.

[0030] <2-2. Hot air unit 2> The hot air unit 2 is provided on the side of the furnace body 1. The hot air unit 2 is controlled by the control device 7, heats air to a high temperature, and sends the hot air into the furnace body 1. The hot air is blown onto the biomass B to heat it. The hot air from the hot air unit 2 flows into the inside of the furnace body 1 from the hot air port 111. For example, the hot air unit 2 has a heating section 21, a blowing section 22, and a shutoff valve 23. The heating section 21 is a heater that generates heat using electricity, for example, including an electric heating wire, and heats the air to a high temperature of 350°C or higher and 600°C or lower, for example. The temperature range of the heated air (i.e., the hot air) is not limited to this example. The blowing section 22 sends out the hot air toward the inside of the furnace body 1. The hot air outlet 111 is a valve disposed between the hot air outlet 111 and the heating section 21 and the blower section 22, and opens and closes under the control of the control device 7 to switch between allowing and not allowing the hot air to flow.

[0031] By heating with hot air, the biomass B in the furnace body 1 can be ignited without using fossil fuels, and further, the charcoal C can be produced by burning the biomass B. Therefore, the time required to produce the charcoal C can be shortened compared to a configuration in which the internal temperature of the furnace body 1 is raised by a burner using fossil fuels such as diesel, kerosene, and LPG (liquefied petroleum gas) and then the biomass B is supplied and burned. In addition, the carbonization furnace 100 of this embodiment can reduce the emission of greenhouse gases such as carbon dioxide compared to the above-mentioned configuration using the combustion of fossil fuels. Furthermore, by applying the charcoal C to agricultural land as a soil conditioner, carbon can be stored in the soil, which can contribute to reducing carbon dioxide emissions (see the J-Credit Scheme certified by the Japanese government). Therefore, the fertility of agricultural land can be improved and carbon neutrality can be achieved.

[0032] <2-3. Fuel supply unit 3> The fuel supply unit 3 is controlled by the control device 7, and supplies the fuel (i.e., biomass B) stored in the fuel supply device 200 to the inside of the furnace body 1 from the supply port 112. For example, the amount of fuel supplied per unit time in the fuel supply unit 3 (hereinafter referred to as the "supply rate"), the supply pattern (supply / stop), etc. are controlled by the control device 7.

[0033] As shown in FIG. 2, in this embodiment, the supply port 112 is disposed between two hot air ports 111 in the circumferential direction. That is, the supply port 112 is located at a position shifted from the hot air port 111 in the circumferential direction. However, this is not limited to the example, and the supply port 112 may be located at the same position as any of the hot air ports 111 in the circumferential direction. In this way, the biomass B supplied from the supply port 112 can be piled up in a mountain shape centered around the hot air port 111. By setting the upper surface fa of the piled layer of the biomass B near the hot air port 111 at an appropriate height position with respect to the height position of the hot air port 111, it is possible to prevent an excess supply of the biomass B into the inside of the furnace body 1. Therefore, the biomass B can be burned appropriately.

[0034] <2-4. Mixing unit 4> The stirring unit 4 is attached to the bottom 13 of the furnace body 1 and is rotatable around the central axis Jc. The stirring unit 4 is controlled by the control device 7 and stirs the biomass B in the furnace body 1. Stirring by the stirring unit 4 can prevent local ignition and combustion of the biomass B. Therefore, the ignition time of the entire biomass B can be shortened, and the biomass B in the furnace body 1 can be burned more uniformly.

[0035] The stirring unit 4 has a shaft member 41, a stirring blade 42, a cone portion 43, and a drive portion 44.

[0036] The shaft member 41 is disposed on the bottom surface of the furnace body 1. The shaft member 41 extends in the vertical direction along a central axis Jc passing through the center of the bottom surface of the furnace body 1, and is rotatable around the central axis Jc. The shaft member 41 is inserted into the central opening 131 from the lower side of the bottom 13, and protrudes above the upper surface of the bottom 13.

[0037] The stirring blade 42 extends radially outward from the shaft member 41 with respect to the shaft member 41 as a reference, and is rotatable around the shaft member 41. An end (for example, a radially outer end) of the stirring blade 42 faces the inner surface of the cylindrical portion 11 of the furnace body 1 in the radial direction with a small gap therebetween.

[0038] In this embodiment, four stirring blades 42 are arranged in the circumferential direction around the shaft member 41 (see FIG. 2). However, this is not limited to the example, and the number of stirring blades 42 may be one or more than four. Furthermore, the multiple stirring blades 42 may be arranged at equal intervals in the circumferential direction, or may be arranged at different intervals.

[0039] Preferably, the radially outer end of the agitating blade 42 based on the shaft member 41 is located below the height position of the upper end of the hot air port 111. More preferably, as shown in FIG. 1, the radially outer end of the agitating blade 42 is located below (the height position of the lower end of) the hot air port 111. In this way, it is possible to suppress or prevent the hot air blown out from the hot air port 111 from directly heating the radially outer end of the agitating blade 42 moving in the circumferential direction. Therefore, it is possible to suppress or prevent thermal damage to the radially outer end of the agitating blade 42, backflow of hot air to the hot air port 111, and the like. In addition, since the biomass B moving due to the agitating blade 42 can be efficiently heated by the hot air, it is possible to efficiently ignite the biomass B and increase its temperature.

[0040] Each mixing blade 42 has a blade portion 421 and a gable portion 422. The blade portion 421 extends radially outward from the shaft member 41 and expands in the vertical direction. The gable portion 422 is disposed at the upper end of the blade portion 421 and extends radially. The upper surface of the gable portion 422 has a triangular shape that is pointed upward in a cross-sectional view seen from the radial direction. The arrangement of the gable portion 422 allows the biomass B placed on the upper surface of the mixing blade 42 to fall downward. Therefore, since the accumulation of biomass B at the upper end of the mixing blade 42 can be prevented, the mixing unit 4 can mix the biomass B more uniformly.

[0041] In this embodiment, the vertical width of the agitating blade 42 is uniform in the radial direction. However, the present invention is not limited to this example, and as shown in Fig. 3A, the radial outer end of the agitating blade 42 may taper downward as it moves radially outward. Fig. 3A is a cross-sectional view showing a modified example of the outer end shape of the agitating blade 42. Fig. 3A corresponds to the portion IIIa surrounded by the rough dashed line in Fig. 1.

[0042] Specifically, at least one of the stirring blades 42 (particularly the blade portion 421) may have an upper end that extends downward as it moves radially outward at a radially outer end portion based on the shaft member 41. Preferably, the gable portion 422 is also disposed at the upper end portion of the tapered radially outer end portion of the blade portion 421.

[0043] In this way, for example, it is possible to reduce the vertical width of the radially outer end of the agitating blade 42 without reducing the vertical width of the part radially inward from the radially outer end of the agitating blade 42, thereby making it possible to reduce the opposing area between the radially outer end of the agitating blade 42 and the hot air port 111. Therefore, it is possible to reduce the risk of the tip portion of the agitating blade 42 (i.e., the radially outer end) being deteriorated by heating, without reducing the agitating effect of the agitating blade 42.

[0044] In this embodiment, the circumferential width of the impeller 42 is uniform in the radial direction. However, this is not limited to the example, and as shown in FIG. 3B, the radial outer end of the impeller 42 may be tapered toward the radial outward direction. FIG. 3B is a top view showing another modified example of the outer end shape of the impeller 42. FIG. 3B corresponds to the portion IIIb surrounded by the rough dashed line in FIG. 2.

[0045] In particular, at the radially outer end portion of at least one stirring blade 42 (particularly blade portion 421) relative to the shaft member 41, the circumferential width of the radially outer end portion may decrease radially outward.

[0046] In this way, for example, the circumferential width of the tip of the agitator 42 can be reduced without reducing the circumferential width of the part radially inward from the radial outer end of the agitator 42 (particularly the blade portion 421). When the radial outer end of the agitator 42 moving in the circumferential direction faces the hot air port 111 in the radial direction, the hot air blown out from the hot air port 111 can flow, for example, in one or the other circumferential direction from the radial outer end of the agitator 42. Therefore, an increase in the blowing resistance of the hot air and backflow to the hot air port 111 can be suppressed or prevented without decreasing the rigidity of the agitator 42.

[0047] The configurations described above with reference to FIG. 3A and FIG. 3B may be implemented in combination as long as no particular contradiction occurs.

[0048] The cone portion 43 has a pyramidal or conical shape that points upward, and is fixed to the upper end of the shaft member 41. The arrangement of the cone portion 43 allows the biomass B placed on the upper end of the shaft member 41 to drop downward. Therefore, accumulation of the biomass B at the upper end of the shaft member 41 can be prevented, and the mixing unit 4 can mix the biomass B more uniformly.

[0049] The drive unit 44 includes, for example, a motor disposed at the lower end of the shaft member 41, and rotates the shaft member 41 together with the stirring blade 42 and the cone portion 43 around the central axis Jc under the control of the control device 7.

[0050] <2-5. Temperature sensor 5> The temperature sensor 5 is a first sensor that detects the internal temperature of the lower part of the furnace body 1 and the temperature of the biomass B accumulated in the furnace body 1, and protrudes radially inward from the inner surface of the cylindrical part 11. The temperature sensor 5 also serves as a second sensor for detecting the height position of the upper surfaces fa, fb of the accumulation layer of the biomass B (or charcoal C) in the furnace body 1. The detection result of the temperature sensor 5 is output to the control device 7.

[0051] In this embodiment, the temperature sensor 5 has a first temperature sensor 51, a second temperature sensor 52, a third temperature sensor 53, and a fourth temperature sensor 54. These are arranged in the vertical direction. For example, the first temperature sensor 51 is arranged above the stirring blade 42. The second temperature sensor 52 is arranged above the first temperature sensor 51. The third temperature sensor 53 is arranged above the second temperature sensor 52. The fourth temperature sensor 54 is arranged above the third temperature sensor 53. The height position of the upper surface fa, fb of the biomass B (or smoked charcoal C) can be detected from the difference in detected temperature between the temperature sensors 5 adjacent to each other in the vertical direction.

[0052] In the ignition control and first temperature rise control process of biomass B, the first temperature sensor 51 is disposed below the target height position of the upper surface fa of the deposition layer of biomass B. The second to fourth temperature sensors 52, 53, 54 are disposed above the target height position of the upper surface fa of the deposition layer of biomass B.

[0053] In the second temperature rise control step and steady operation of the furnace body 1, the first to third temperature sensors 51, 52, and 53 are disposed below the target height position of the upper surface fb of the pile layer of the biomass B (or charcoal C). The fourth temperature sensor 54 is disposed above the target height position of the upper surface fb of the pile layer of the biomass B.

[0054] In addition, the number of temperature sensors 5 arranged vertically in the furnace body 1 is four in this embodiment, but is not limited to this example and may be a number other than four. In addition, the second sensor for detecting the pile height of the biomass B may be a means other than the temperature sensor 5.

[0055] <2-6. Upper temperature sensor 6> The upper temperature sensor 6 is disposed above the upper air supply port 114 and protrudes radially inward from the inner surface of the cylindrical portion 11. The upper temperature sensor 6 detects the internal temperature, for example, in the high oxygen region of the furnace body 1, and outputs it to the control device 7.

[0056] <2-7.Control device 7> The control device 7 controls each of the components of the carbonization furnace 100, and also controls the devices 200, 300, 400, and 500 other than the carbonization furnace 100 that constitute the carbonization apparatus 500. The control device 7 has a memory 71 and an input unit 72. The memory 71 is a non-transitory storage medium. The input unit 72 accepts operation inputs from a user. The control device 7 controls the above-mentioned components and devices based on, for example, the programs and information stored in the memory 71, the operation inputs accepted by the input unit 72, the detection results of the temperature sensor 5 and the upper temperature sensor 6, and the like.

[0057] For example, the control device 7 controls the hot air unit 2, for example, driving and stopping the hot air unit 2, the temperature of the hot air to be sent out, the flow rate of the hot air, etc. The control device has a first temperature rise control mode and a second temperature rise control mode. In the first temperature rise control mode, the hot air unit 2 is driven to ignite the biomass B and heat it up to a first target temperature (for example, 600°C: see the detection temperature T5 in FIG. 4 described later). In the second temperature rise control mode, after the hot air unit 2 is stopped, the internal temperature of the furnace body 1 is heated up to a second target temperature by the combustion of the biomass B itself. The second target temperature is, for example, 900°C, which is higher than the first target temperature (for example, see the detection temperature T7 in FIG. 5 described later). In this way, smoky charcoal C can be produced by burning the ignited biomass B.

[0058] The control device 7 also controls the agitation unit 4. Preferably, when starting to drive the hot air unit 2, the control device 7 rotates the radially outer end of the agitation blade 42 to a position circumferentially shifted from the hot air port 111, and then drives the hot air unit 2. This makes it possible to prevent the outer end (i.e., the radially outer end) of the agitation blade 42 from being directly heated by hot air. Therefore, the biomass B can be directly heated and ignited by hot air, and the risk of the outer end of the agitation blade 42 being deteriorated by heating can be reduced.

[0059] Also, preferably, the control device 7 drives the stirring unit 4 intermittently when the rate of temperature rise of the upper surface of the piled layer of biomass B in the furnace body 1 becomes equal to or greater than a predetermined value. The predetermined value is, for example, equal to or greater than 5°C / sec (see ΔT1s in FIG. 4 described later). In this way, the biomass B that has started to burn due to ignition can be moved by stirring. Therefore, an excessive temperature rise in the biomass B due to heating with hot air can be prevented, and other unignited biomass B can be ignited by the hot air. Also, by continuing to locally heat the biomass B with hot air during the stirring stop period, the temperature of the unignited biomass B can be raised to the ignition temperature. Therefore, the biomass B can be ignited and burned more reliably and efficiently.

[0060] Preferably, the control device 7 gradually changes the combustion conditions of the biomass B after the biomass B in the furnace body 1 is ignited. For example, the control device 7 gradually changes at least one of the stirring angle per cycle, the stirring time per cycle, and the stirring stop time per cycle in the intermittently driven stirring unit 4 in response to a temperature rise in the biomass B (see time points P3 to P5 in FIG. 6, which will be described later). In this way, the stirring operation of the stirring unit 4 can be appropriately adjusted in response to the temperature rise of the biomass B (and the charcoal C) (i.e., the progress of combustion).

[0061] However, the above example does not exclude a configuration in which the control device 7 causes the agitation unit 4 to rotate continuously from the start of driving.

[0062] Also, preferably, the control device 7 continuously drives the agitation unit 4 when the temperature of the biomass B exceeds a first predetermined value. For example, as described below, when the temperatures detected by the first temperature sensor 51 to the fourth temperature sensor 54 reach 300° C., the control device 7 continuously rotates the agitation blades 42. In this way, the temperature distribution of the biomass B can be made uniform, while promoting the combustion of the biomass B.

[0063] However, the above example does not exclude a configuration in which, among the combustion conditions, at least the drive of the agitation unit 4 is performed under a certain condition after the biomass B in the furnace body 1 is ignited.

[0064] Furthermore, the control device 7 controls the fuel supply unit 3 based on the detection result of the second sensor (the temperature sensor 5 in this embodiment), for example, controlling the driving and stopping of the fuel supply unit 3, the supply speed and supply time of the biomass B, etc. In this way, the control device 7 controls the accumulation height of the biomass B. For example, when driving the hot air unit 2, the control device 7 sets the height position of the upper surface fa of the biomass B accumulated in the furnace body 1 on the radial outer side of the hot air port 111 to be equal to or lower than the height position of the upper end of the hot air port 111, and higher than the height position of the lower end of the hot air port 111. In this way, the upper layer portion of the accumulated biomass B can be heated by hot air, and the biomass B can be burned appropriately and continuously.

[0065] In addition, the control device 7 adjusts the flow rate of the air supplied into the furnace body 1 according to the internal temperature of the furnace body 1. For example, when the internal temperature of the furnace body 1 exceeds a second predetermined value, the control device 7 stops driving the hot air unit 2 and increases the flow rate V2 of the air flowing into the furnace body 1 from the upper air supply port 114 (see time point P6 in FIG. 6 described later). The second predetermined value is, for example, 600°C, which is higher than the first predetermined value. For example, in this embodiment, the control device 7 keeps the total amount of air supplied into the furnace body 1 per unit time constant, while increasing the number of upper air supply ports 114 that supply air. This makes it possible to increase the flow rate of the air flowing out from each upper air supply port 114. However, this is not limited to this example, and the total amount of air supplied into the furnace body 1 per unit time does not need to be constant as long as the internal temperature in the furnace body 1 does not change significantly.

[0066] When the temperature of the biomass B increases, the resulting rising air current contains more combustibles such as graphite. Therefore, by increasing the flow velocity V2 of the air flowing in from the upper air supply port 114, the combustibles can be efficiently burned in the furnace body 1. Therefore, the amount of combustibles contained in the air discharged to the outside of the furnace body 1 can be reduced or eliminated.

[0067] In this embodiment, the control device 7 is a component of the carbonization furnace 100. However, without being limited to this example, at least a part of the control device 7 may be a component separate from the carbonization furnace 100 in the carbonization apparatus 500. In addition, a part of the control performed by the control device 7 may be performed manually.

[0068] <3. Example of producing charcoal C by burning biomass B> Next, an example of the production of smoky charcoal C in the carbonization apparatus 500 will be described with reference to Figs. 4 to 6. Fig. 4 is a flow chart for explaining an example of the ignition of biomass B using the hot air unit 2 and the first temperature rise control process of the furnace body 1. Fig. 5 is a flow chart for explaining an example of the second temperature rise control process of the furnace body 1 by combustion of the biomass B itself. Fig. 6 is a time chart showing an example of the production of smoky charcoal C in the carbonization apparatus 500. Each step shown in Figs. 4 to 6 is performed based on the control of the control device 7.

[0069] <3-1. Ignition of biomass B using hot air unit 2 and first temperature rise control process> 4, in this step, the carbonization device 500 and the carbonization furnace 100 ignite the biomass B by the hot air unit 2 and expand the ignition range. Then, the carbonization device 500 and the carbonization furnace 100 increase the temperature of the biomass B to a temperature at which combustion can be continued without using the hot air unit 2 by the first temperature increase control.

[0070] First, at time P0 in Fig. 6, it is determined whether the circumferential position of the radially outer end (i.e., the outer end) of at least one of the stirring blades 42 overlaps with the circumferential position of the hot air port 111 (step S101). In other words, it is determined whether the two are radially opposed when viewed from above and below. This determination can be made, for example, by checking whether the rotational angle position of the shaft member 41 is the same as the rotational angle position at which the two are opposed. Alternatively, this determination may be made based on the result of detecting the rotational angle position of the shaft of the motor (i.e., the drive unit 44) that rotates the shaft member 41 using an encoder, a Hall element, or the like.

[0071] If the circumferential positions of the two described above overlap (YES in step S101), the drive unit 44 rotates the shaft member 41 to shift the radial outer end of the mixing blade 42 in the circumferential direction from the hot air port 111 (step S102). Then, proceed to step S103. On the other hand, if the circumferential positions of the two described above do not overlap (NO in step S101), proceed to step S103.

[0072] Next, a predetermined amount of biomass B is supplied into the furnace body 1 by driving the fuel supply unit 3 (step S103). During this initial supply, the supply amount of biomass B is controlled by the supply speed of biomass B by the fuel supply unit 3 and the supply time. The supply amount of biomass B at this time is set to an amount that does not generate too much combustible gas from the ignited biomass B and does not prolong the ignition time of biomass B too much. For example, the supply amount is set to an amount that the upper surface fa of the pile layer of biomass B near the temperature sensor 5 is located above the first temperature sensor 51 and below the second temperature sensor 52. Supply conditions that satisfy this are determined, for example, based on the results of multiple demonstration experiments performed in advance.

[0073] When the initial supply of biomass B is completed, at time P1 in FIG. 6, air supply is started at the lower air supply port 113 and the shutoff valve 23 of the hot air unit 2 is opened (step S104). After that, the hot air unit 2 is started and hot air is supplied into the furnace body 1 (step S105). As a result, the biomass B is locally heated by the hot air blown out from the hot air port 111, and ignition of the biomass B is started. In addition, by starting the hot air unit 2 after an appropriate amount of air is supplied at the lower air supply port 113, the oxygen concentration in the lower part of the furnace body 1 is increased, and the accumulation of combustible gas generated from the ignited biomass B can be suppressed. Therefore, it is possible to prevent the accumulated combustible gas from burning all at once. In addition, the amount of air supplied per unit time at the lower air supply port 113 (hereinafter referred to as the air supply speed) Qa1 in step S104 is set to an amount that does not extinguish the ignited biomass B.

[0074] At this time, the hot air heats the upper layer of the accumulated biomass B, and the biomass B is burned appropriately and continuously. If the middle layer or lower part of the biomass B is heated and burned with hot air, there is a risk that the gas and charcoal C will flow back into the hot air port 111 due to a local temperature rise in the biomass B and gas generation due to combustion. In addition, if a large amount of hot air is blown onto the upper surface fa of the accumulated biomass B, the temperature of the biomass B near the upper surface fa will rise, but the temperature of the biomass B in a portion away from the upper surface fa below is unlikely to rise. Therefore, even if the biomass B near the upper surface fa is ignited, there is a risk that the combustion cannot be continued.

[0075] Next, the first temperature increase control of the furnace body 1 using the hot air unit 2 is carried out. First, it is determined whether or not the temperature increase rate ΔT1 of the first temperature sensor 51 is equal to or greater than a predetermined value ΔT1s (step S106). At this time, preferably, it is determined whether or not the continuous period t1 during which ΔT1≧ΔT1s at the first temperature sensor 51 is equal to or greater than a predetermined period t1s. Note that the first temperature sensor 51 is, at this point, below the upper surface fa of the deposition layer of the biomass B among the temperature sensors 5 and is an example of the temperature sensor closest to the upper surface fa in the vertical direction. Further, the temperature increase rate ΔT1 is the increase rate [°C / second] of the detected temperature T1 per unit time at the first temperature sensor 51 in step S106, and is, for example, several [°C / second]. The predetermined value ΔT1s is a threshold value of the temperature increase rate ΔT1 and is set to, for example, 5 [°C / second] or more. The predetermined period t1s is a threshold value of the continuous period t1 and is, for example, several tens [sec]. By determining the success or failure of ignition based on the continuous period t1, it is possible to suppress an erroneous determination of the detected temperature due to noise at the time of temperature detection.

[0076] Note that if ΔT1<ΔT1s (preferably t1<t1s) (NO in step S106), it is determined that the initial ignition of the biomass B has failed, and the carbonization device 500 including the carbonization furnace 100 is stopped (step S107), and the production of the charcoal C is terminated. Alternatively, when NO in step S106, steps S105 and S106 may be executed again. At this time, when the determination of NO in step S106 continues and reaches a predetermined number of times, it is determined that ignition has failed, and the carbonization device 500 is stopped. Further, when it is determined that ignition has failed, a predetermined message (such as a warning) may be displayed on a monitor (not shown) mounted on the control device 7 or the like, or a warning sound or a predetermined message voice may be output from a speaker mounted on the control device 7 or the like.

[0077] On the other hand, if ΔT1≧ΔT1s (preferably t1≧t1s) (YES in step S106), at the time point P2 in FIG. 6, it is determined that the initial ignition of the biomass B has succeeded, and the supply of the biomass B is restarted. Further, the stirring unit 4 is driven, and the conditions are changed step by step to increase the temperature of the biomass B.

[0078] For example, biomass B is continuously supplied into the furnace body 1 by driving the fuel supply unit 3 (step S108). At this time, the supply rate Qb1 [kg / hr] of the biomass B is set to be less than the supply rate Qb2 in the subsequent second temperature rise control step (see FIG. 5). This makes it possible to prevent the ignited biomass B from being covered with unignited biomass B and being extinguished.

[0079] Further, intermittent driving of the agitation unit 4 is started (step S109). In this embodiment, for example, the agitation unit 4 is driven intermittently, and a driving cycle is repeated in which the agitation unit 4 is driven for several seconds to rotate to a predetermined rotation angle (for example, 72 degrees) and then stopped for several minutes. The rotation angle, driving period, and stop period of the agitation unit 4 (particularly the agitation blade 42) are set to a degree that allows unignited biomass B moved by agitation to be ignited reliably. For example, if the stop period is too short, there is a risk that the biomass B will move by agitation before being ignited. Furthermore, if the rotation angle and driving period are too large, there is a risk that the unignited biomass B will move above the discharge port 132. On the other hand, if the stop period is too long or the rotation angle and driving period are too small, there is a risk that the combustion of the biomass B will proceed too much.

[0080] After the stirring unit 4 starts to be driven, the rotary valve 14 and the charcoal conveying device 300 start to be driven (step S110). As a result, the charcoal C is discharged from the discharge port 132, and is transported by the charcoal conveying device 300 to the filling device 400 and bagged. The discharge amount of the charcoal C by the rotary valve 14 per unit time (hereinafter referred to as the "discharge speed") is appropriately adjusted according to the progress of the combustion of the biomass B. If the discharge speed is too fast, there is a risk that the biomass B that has not been sufficiently burned will be discharged. If the discharge speed is too slow, there is a risk that the charcoal C will be burned excessively. Here, when some biomass B such as rice husk is burned excessively, fine needle-like silica is generated and mixed with the charcoal C. Therefore, the discharge speed of the rotary valve 14 is determined based on the results of, for example, multiple demonstration experiments conducted in advance.

[0081] Next, it is determined whether the detected temperature T2 of the first temperature sensor 51 is equal to or greater than a predetermined value T2s (step S111). At this time, it is preferably determined whether the duration t2 of T2≧T2s is equal to or greater than the predetermined period t2s in the first temperature sensor 51. The first temperature sensor 51 is an example of a temperature sensor that is located below the upper surface fa of the deposition layer of the biomass B at this time and is closest to the upper surface fa in the vertical direction. The detected temperature T2 is the detection result of the first temperature sensor 51 in step S111. The predetermined value T2s is a threshold value of the detected temperature T2, and is, for example, 450° C. The predetermined period t2s is a threshold value of the duration t2, and is, for example, 1 sec or more. By determining whether ignition is successful based on the duration t2, it is possible to suppress erroneous determination of the detected temperature T2 due to noise during temperature detection.

[0082] If T2≧T2s (preferably t2≧t2s) (YES in step S111), the drive conditions of the agitation unit 4 are changed at time point P3 in FIG. 6, and agitation by the agitation blade 42 is promoted (step S112). For example, the rotation angle, drive period, and stop period of the agitation unit 4 (particularly the agitation blade 42) are changed. In this embodiment, the stop period of the intermittently driven agitation unit 4 is shortened, and is made shorter than the stop period in step S109. By promoting agitation, the ignited biomass B can be spread more quickly inside the furnace.

[0083] Next, it is determined whether the temperature T3 detected by the temperature sensor 5 is equal to or greater than a predetermined value T3s (step S113). At this time, it is preferably determined whether the duration t3 of T3≧T3s in the temperature sensor 5 is equal to or greater than the predetermined period t3s. The detected temperature T3 is a detection result of any one of the first to fourth temperature sensors 51, 52, 53, 54 in step S113, and is, for example, the highest temperature among the temperatures detected by the first to fourth temperature sensors 51, 52, 53, 54. The predetermined value T3s is a threshold value of the detected temperature T3, and is, for example, 600° C. The predetermined period t3s is a threshold value of the duration t3, and is, for example, 1 sec or more. By determining based on the duration t3, it is possible to suppress erroneous determination of the detected temperature T3 due to noise during temperature detection.

[0084] If T3≧T3s (preferably t3≧t3s) (YES in step S113), the air supply velocity Qa2 of the lower air supply port 113 is increased at time point P4 in Fig. 6 (step S114). By increasing the oxygen supplied to the low-oxygen region at the bottom of the furnace body 1, the combustion of the biomass B can be further promoted.

[0085] Next, it is determined whether the detected temperature T4 of the first to fourth temperature sensors 51, 52, 53, 54 is equal to or greater than the predetermined value T4s (step S115). At this time, it is preferably determined whether the duration t4 of T4≧T4s is equal to or greater than the predetermined period t4s in the first to fourth temperature sensors 51, 52, 53, 54. The detected temperature T4 is the detection result of the first to fourth temperature sensors 51, 52, 53, 54 in step S115, and includes, for example, all the detected temperatures of the first to fourth temperature sensors 51, 52, 53, 54. The predetermined value T4s is an example of the "first predetermined value" of the present invention, and is a threshold value of the detected temperature T4, and is, for example, 600[°C]. In the present embodiment, T4s=T3s, but is not limited to this example, and may be T4s≠T3s. The predetermined period t4s is a threshold value of the duration t4, and is, for example, 1[sec] or more. By making the determination within the duration t4, it is possible to prevent erroneous determination of the detected temperature T4 due to noise during temperature detection.

[0086] If T4≧T4s (preferably t4≧t4s) (YES in step S115), the agitation unit 4 is continuously driven and constantly rotates at time P5 in Fig. 6 (step S116). This can further promote uniformity of the pile height of biomass B and combustion of biomass B.

[0087] Furthermore, air supply through the upper air supply port 114 is started (step S117). The flow velocity V1 of the air supplied into the furnace body 1 at this time is made faster than that during the second temperature rise control process (see FIG. 5) of the furnace body 1 due to the subsequent combustion of the biomass B itself. For example, the total amount of air supply per unit time through the multiple upper air supply ports 114 in step S117 is made the same as that during the second temperature rise control process, while the number of upper air supply ports 114 supplying air into the furnace body 1 in step S117 is made, for example, two, which is less than the number (for example, four) in the second temperature rise control process. This makes it possible to make the air flow velocity V1 faster at each upper air supply port 114. However, the means for increasing the flow velocity V1 is not limited to the above example. For example, the valve of the upper air supply port 114 may be closed slightly to reduce the cross-sectional area of ​​the air flow path. When the combustion of the biomass B is promoted, the amount of combustible gas and combustible material in the high-oxygen region in the furnace body 1 increases. The total amount of air supplied through the multiple upper air inlets 114 is set to an amount sufficient to maintain the combustion of the combustible gas and combustible materials in the high-oxygen region of the furnace body 1. The flow velocity V1 at each upper air inlet 114 is set to an amount sufficient to sufficiently combust the combustible gas and combustible materials in the high-oxygen region of the furnace body 1, while preventing the internal temperature of the furnace body 1 from decreasing and preventing backflow of gas from the inside of the furnace body 1 to the supply port 112. If the flow velocity V1 is too small, a large amount of combustible gas and combustible materials will be discharged to the outside through the flue 15 due to incomplete combustion. If the flow velocity V1 is too large, the internal temperature of the furnace body 1 will decrease and backflow will occur at the supply port 112.

[0088] Next, it is determined whether the detected temperature T5 of the first temperature sensor 51 is equal to or greater than a predetermined value T5s (step S118). At this time, it is preferably determined whether the duration t5 of T5≧T5s is equal to or greater than the predetermined period t5s in the first temperature sensor 51. The first temperature sensor 51 is an example of a temperature sensor that is located below the upper surface fa of the deposition layer of the biomass B at this time and is the closest to the upper surface fa in the vertical direction. The detected temperature T5 is the detection result of the first temperature sensor 51 in step S118. The predetermined value T5s is an example of the "second predetermined value" of the present invention, and is a threshold value of the detected temperature T5, for example, 900° C. The predetermined period t5s is a threshold value of the duration t5, for example, 1 sec or more. By determining based on the duration t5, it is possible to suppress erroneous determination of the detected temperature T5 due to noise during temperature detection.

[0089] If T5≧T5s (preferably t5≧t5s) (YES in step S118), the shutoff valve 23 is closed and the hot air unit 2 is stopped (step S119). This ends the ignition of biomass B using the hot air unit 2 and the first temperature rise control process of the furnace body 1 in Fig. 4. Then, at time point P6 in Fig. 6, the second temperature rise control process of the furnace body 1 by combustion of the biomass B itself in Fig. 5, which will be described next, is started.

[0090] 4, the agitation unit 4 is intermittently driven during the period from steps S109 to S115 (between time points P2 to P5 in FIG. 6). However, without being limited to this example, the agitation unit 4 may be continuously operated at a low rotation speed at which the biomass B can be ignited by hot air. For example, during the period from steps S109 to S115, the agitation unit 4 may be continuously operated at a rotation speed lower than the rotation speed after step S116 (i.e., after time point P5 in FIG. 6).

[0091] <3-2. Second temperature rise control process of the furnace body 1 by combustion of the biomass B itself> 5, in this process, the carbonization device 500 and the carbonization furnace 100 use heat generated by the combustion of the biomass B (and smoky coal C) to raise and maintain the internal temperature in the furnace body 1 to a target temperature, and produce smoky coal C in a steady operation state. In this process, the stirring unit 4 and the rotary valve 14 are continuously driven at all times.

[0092] 6, the supply rate Qb2 of biomass B in the fuel supply device 200 is increased (step S201), and the air supply rate Qa3 of the lower air supply port 113 is reduced to a level at which the combustion of biomass B is not suppressed (step S202). If the air supply rate Qa3 is too low, the combustion rate of biomass B (and charcoal C) decreases, and the charcoal C remains undercooked for a long period of time.

[0093] Furthermore, the flow velocity V2 of the air supplied from the upper air inlets 114 into the furnace body 1 is slowed down (step S203). For example, the number of upper air inlets 114 supplying air into the furnace body 1 in step S203 is increased to four, which is greater than the number (for example, two) in the first temperature rise control step. This makes it possible to make the air flow velocity V2 in each upper air inlet 114 slower than the flow velocity V1 in the first temperature rise control step, thereby suppressing a drop in the internal temperature of the furnace body 1. However, the means for slowing down the flow velocity V2 is not limited to the above example. For example, the valve of the upper air inlet 114 may be slightly opened to increase the air flow path cross-sectional area. Here, preferably, the total amount of air supplied per unit time at the multiple upper air inlets 114 in step S203 is made the same as that in the first temperature rise step (see FIG. 4). For example, if the total amount of air supplied per unit time is increased, the internal temperature in the furnace body 1 may drop, and the combustion efficiency of the combustible gas and combustibles may decrease. However, this example does not exclude a configuration in which the total amount of air supplied per unit time through the upper air supply ports 114 in step S203 is different from that in the first heating step. For example, the total amount of air supplied per unit time through the upper air supply ports 114 in step S203 may be increased to an extent that does not excessively lower the internal temperature in the furnace body 1, or may be decreased to an extent that does not excessively lower the amount of combustion of combustible gas and combustibles.

[0094] Next, it is determined whether the detected temperature T6 of the first to fourth temperature sensors 51, 52, 53, 54 is equal to or greater than a predetermined value T6s (step S204). At this time, it is preferably determined whether the duration t6 of T6≧T6s is equal to or greater than the predetermined period t6s in the first to fourth temperature sensors 51, 52, 53, 54. The detected temperature T6 is the detection result of the first to fourth temperature sensors 51, 52, 53, 54 in step S204, and includes all the detected temperatures of the first to fourth temperature sensors 51, 52, 53, 54, for example. The predetermined value T6s is a threshold value of the detected temperature T6, and is, for example, 750° C. The predetermined period t6s is a threshold value of the duration t6, and is, for example, 1 sec or more. By determining based on the duration t6, it is possible to suppress erroneous determination of the detected temperature T6 due to noise during temperature detection.

[0095] When the heat storage of the furnace wall of the furnace body 1 progresses, the combustion of the biomass B (and the charcoal C) is further promoted by radiation in the furnace body 1. Therefore, if T6 ≧ T6s (preferably t6 ≧ t6s) (YES in step S204), the air supply to the lower air supply port 113 is stopped at time point P7 in FIG. 6 (step S205). This makes it possible to suppress excessive combustion of the biomass B (and the charcoal C) and improve the yield of the charcoal C. In addition, since the air supply unit 115 connected to the lower air supply port 113 can be stopped, it is possible to save electricity and prevent noise generation in the air supply unit 115. Furthermore, since the internal pressure of the furnace body 1 can be reduced, it is possible to reduce the air supply load on the air supply unit 115 connected to the upper air supply port 114. Therefore, it is possible to reduce the power consumption of the air supply unit 115 connected to the upper air supply port 114. Even if the air supply through the lower air supply port 113 is stopped, the air supplied through the upper air supply port 114 can maintain the combustion of the biomass B (and charcoal C), and the temperature of the biomass B can be maintained by the reaction heat.

[0096] Next, it is determined whether the detected temperature T7 of the upper temperature sensor 6 arranged in the furnace body 1 is equal to or greater than a predetermined value T7s (step S206). At this time, it is preferably determined whether the duration t7 of T7≧T7s in the upper temperature sensor 6 is equal to or greater than the predetermined period t7s. The detected temperature T7 is the detection result of the upper temperature sensor 6 in step S206. The predetermined value T7s is a threshold value of the detected temperature T7, for example, 900° C. The predetermined period t7s is a threshold value of the duration t7, for example, 15 min or more. By determining based on the duration t7, it is possible to suppress erroneous determination of the detected temperature T7 due to noise during temperature detection.

[0097] By stopping the air supply from the lower air supply port 113, the combustible gas and combustible materials generated by the combustion of the biomass B (and the charcoal C) are burned by the air supplied from the upper air supply port 114. Therefore, the temperature inside the furnace body 1 rises sharply. In addition, since the total amount of air supplied to the furnace body 1 decreases, these are likely to be incompletely combusted. Therefore, if T7 ≧ T7s (preferably t7 ≧ t7s) (YES in step S206), at the time point P8 in FIG. 6, temperature adjustment inside the furnace body 1 by the flow velocity V2 of the air supplied from the upper air supply port 114 (and the increase / decrease in the amount of air supplied per unit time) (hereinafter referred to as furnace temperature adjustment control) is started (step S207). As a result, even if the air supply from the lower air supply port 113 is stopped, the temperature inside the furnace body 1 can be controlled, and the concentration of a specific gas (such as carbon monoxide) contained in the exhaust gas from the furnace body 1 to the outside can be controlled so as not to exceed a reference value.

[0098] Furthermore, after a predetermined operating period (e.g., several tens of minutes) has elapsed since the start of the furnace temperature adjustment control (YES in step S208), at time point P9 in Fig. 6, temperature adjustment inside the furnace body 1 by adjusting the supply rate Qb2 of biomass B in the fuel supply device 200 (hereinafter referred to as fuel supply control) is started (step S209). This makes it possible to suppress temperature fluctuations inside the furnace body 1 due to the supply of biomass B into the furnace body 1 and maintain it at the target temperature.

[0099] Then, at time P10 in Fig. 6, steady operation of the carbonization apparatus 500 and the carbonization furnace 100 is started. When the steady operation ends (YES in step S210), the process in Fig. 5 ends (see time PE in Fig. 6). The steady operation of the carbonization apparatus 500 and the carbonization furnace 100 is stopped, for example, when the supply of the fuel (i.e., biomass B) stored in the fuel supply device 200 is completed, or an input to stop operation is received at the input unit 72 of the control device 7.

[0100] <4. Notes> The embodiment of the present invention has been described above. Note that the above embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each process, and that such modifications are within the scope of the present invention.

[0101] <5. Summary> The embodiments described thus far will be summarized below.

[0102] For example, the carbonization furnace 100 disclosed herein may include: A furnace body 1 that accommodates biomass B; A hot air unit 2 provided on a side of the furnace body 1 and sending hot air into the furnace body 1; A stirring unit 4 that stirs the biomass B in the furnace body 1; The configuration is a first configuration.

[0103] The carbonization furnace 100 of the first configuration is as follows: Further comprising a control device 7 for controlling the hot air unit 2, The control device 7 is a first temperature rise control mode in which the biomass B is ignited by driving the hot air unit 2 to raise the temperature to a first target temperature (for example, T5s); a second temperature rise control mode in which, after the hot air unit 2 is stopped, the internal temperature of the furnace body 1 is raised to a second target temperature (e.g., T7s) higher than the first target temperature (e.g., T5s) by combustion of the biomass B itself; The second configuration may be one having the above structure.

[0104] In addition, the carbonization furnace 100 having the first or second configuration has the following features: A control device 7 for controlling the agitation unit 4; A first sensor 5 for detecting the temperature of the biomass B; Further equipped with The control device 7 may be configured (third configuration) to intermittently drive the stirring unit 4 when a temperature rise rate ΔT1 of the upper surface fa of the deposition layer of the biomass B in the furnace body 1 becomes equal to or greater than a predetermined value ΔT1s.

[0105] Moreover, the carbonization furnace 100 having the third configuration is as follows: The control device 7 may be configured (fourth configuration) to change at least one of the stirring angle per cycle, the stirring time per cycle, and the stirring stop time per cycle in the intermittently driven stirring unit 4 in response to the temperature increase of the biomass B.

[0106] Moreover, the carbonization furnace 100 having the third or fourth configuration described above has the following features: The control device 7 may be configured to continuously drive the agitation unit 4 when the temperature T4 of the biomass B exceeds a first predetermined value T4s (a fifth configuration).

[0107] Moreover, the carbonization furnace 100 having the fifth configuration is Further, an air supply part 115 is provided to supply air to the inside of the furnace body 1. A hot air port 111 and an upper air supply port 114 located on the inner surface of the furnace body 1 are arranged, The hot air from the hot air unit 2 flows into the inside of the furnace body 1 through the hot air port 111, The air supplied by the air supply unit 115 flows into the furnace body 1 through the upper air supply port 114, The control device 7 may be configured (sixth configuration) to stop driving the hot air unit 2 and slow down the flow velocity V2 of the air flowing into the inside of the furnace body 1 from the upper air supply port 114 when the temperature T5 of the biomass B exceeds a second predetermined value T5s higher than the first predetermined value T4s.

[0108] In addition, the carbonization furnace 100 having any one of the first to sixth configurations described above has the following features: Further comprising a control device 7 for controlling the stirring unit 4, The stirring unit 4 is A shaft member 41 disposed on the bottom surface of the furnace body 1 and extending in the vertical direction; A stirring blade 42 rotatable around the shaft member 41; having A hot air port 111 through which the hot air from the hot air unit 2 flows into the inside of the furnace body 1 is arranged on the inner surface of the furnace body 1. The control device 7 may be configured (seventh configuration) to rotate the end of the mixing blade 42 to a position circumferentially offset from the hot air port 111 when starting to drive the hot air unit 2, and then drive the hot air unit 2.

[0109] In addition, the carbonization furnace 100 having any one of the first to seventh configurations described above has the following features: The stirring unit 4 is A shaft member 41 disposed on the bottom surface of the furnace body 1 and extending in the vertical direction; A stirring blade 42 rotatable around the shaft member 41; having A hot air port 111 through which the hot air from the hot air unit 2 flows into the inside is arranged on the inner surface of the lower part of the furnace body 1. The end of the stirring blade 42 may be configured to be located lower than the height position of the upper end of the hot air port 111 (eighth configuration).

[0110] In addition, the carbonization furnace 100 having any one of the first to eighth configurations described above has the following features: A fuel supply unit 3 that supplies the biomass B to the inside of the furnace body 1; A second sensor 5 for detecting the height of the upper surface of the deposition layer of the biomass B; a control device (7) for controlling the fuel supply unit (3) based on a detection result of the second sensor (5); Further equipped with A hot air port 111 through which the hot air from the hot air unit 2 flows into the inside of the furnace body 1 is arranged on the inner surface of the furnace body 1. The control device 7 may be configured (9th configuration) to, when driving the hot air unit 2, set the height position of the upper surface fa of the biomass B accumulated in the furnace body 1 on the radially outer side of the hot air outlet 111 below the height position of the upper end of the hot air outlet 111 and above the height position of the lower end of the hot air outlet 111.

[0111] Moreover, the carbonization furnace 100 having the ninth configuration is as follows: The control device 7 may further be configured (tenth configuration) to set the height position of the upper surface fa of the biomass B accumulated in the furnace body 1 on the radially outer side of the hot air port 111 below the height position of the upper end of the hot air port 111 when driving the hot air unit 2.

[0112] In addition, the carbonization furnace 100 having any one of the first to tenth configurations described above has the following features: The furnace further includes a fuel supply unit 3 that supplies the biomass B to the inside of the furnace body 1, A hot air port 111 and a supply port 112 are arranged on the inner surface of the furnace body 1. The hot air from the hot air unit 2 flows into the inside of the furnace body 1 through the hot air port 111, The biomass B is supplied from the supply port 112 into the inside of the furnace body 1, The supply port 112 may be configured to be above the hot air port 111 and at the same position as the hot air port 111 in the circumferential direction (eleventh configuration). [Explanation of symbols]

[0113] 1...furnace body, 11...tube section, 111...hot air port, 112...supply port, 113...lower air inlet, 114...upper air inlet, 1141...valve, 115...air inlet section, 12...lid section, 121...exhaust port, 13...bottom section, 131...central opening, 1311...valve, 132...discharge port, 14...rotary valve, 141...drive section, 15...flue, 2...hot air unit, 21...heat generating section, 22...blower section, 23...shutoff valve, 3...fuel supply unit, 31...supply section, 203...drive section, 4...mixing unit, 41...shaft member, 42...mixing Agitating blade, 421...blade portion, 422...gable portion, 43...cone portion, 44...drive portion, 5...temperature sensor, 51...first temperature sensor, 52...second temperature sensor, 53...third temperature sensor, 54...fourth temperature sensor, 6...upper temperature sensor, 7...control device, 71...memory, 72...input portion, 100...carbonization furnace, 200...fuel supply device, 300...charcoal transport device, 301...transport portion, 302...drive portion, 400...filling device, 401...bag, 402...water spray portion, 500...carbonization device, Jc...central axis, B...biomass, C...smoked charcoal

Claims

1. A furnace body that accommodates biomass; A hot air unit provided on a side surface of the furnace body and sending hot air into the furnace body; A stirring unit that stirs the biomass in the furnace body; A carbonization furnace equipped with:

2. Further comprising a control device for controlling the hot air unit, The control device includes: A first temperature rise control mode in which the hot air unit is driven to ignite the biomass and raise the temperature to a first target temperature; A second temperature rise control mode in which the internal temperature of the furnace body is raised to a second target temperature higher than the first target temperature by combustion of the biomass itself after the hot air unit is stopped. The carbonization furnace according to claim 1 ,

3. A control device for controlling the stirring unit; A first sensor for detecting a temperature of the biomass; Further equipped with The carbonization furnace according to claim 1 , wherein the control device intermittently drives the stirring unit when a rate of temperature increase of an upper surface of the biomass pile layer in the furnace body reaches or exceeds a predetermined value.

4. The carbonization furnace described in claim 3, wherein the control device changes at least one of the stirring angle per cycle, the stirring time per cycle, and the stirring stop time per cycle in the intermittently driven stirring unit in response to a temperature increase of the biomass.

5. The carbonization furnace according to claim 3 , wherein the control device continuously drives the agitation unit when a temperature of the biomass exceeds a first predetermined value.

6. Further, an air supply unit is provided to supply air to the inside of the furnace body, A hot air port and an upper air supply port located in the furnace body are arranged on the inner surface of the furnace body, The hot air from the hot air unit flows into the inside of the furnace body through the hot air port, The air supplied by the air supply unit flows into the furnace body through the upper air supply port, The carbonization furnace described in claim 5, wherein the control device stops driving the hot air unit and slows down the flow rate of air flowing into the inside of the furnace body from the upper air intake port when the temperature of the biomass exceeds a second predetermined value higher than the first predetermined value.

7. A control device for controlling the stirring unit is further provided. The stirring unit comprises: A shaft member disposed on the bottom surface of the furnace body and extending in the vertical direction; A stirring blade rotatable around the shaft member; having A hot air port through which the hot air from the hot air unit flows into the inside of the furnace body is arranged on the inner surface of the furnace body, The carbonization furnace described in claim 1, wherein when the control device starts driving the hot air unit, the control device rotates the end of the stirring blade to a position circumferentially offset from the hot air port, and then drives the hot air unit.

8. The stirring unit comprises: A shaft member disposed on the bottom surface of the furnace body and extending in the vertical direction; A stirring blade rotatable around the shaft member; having A hot air port through which the hot air from the hot air unit flows into the inside is arranged on the inner surface of the lower part of the furnace body, The carbonization furnace according to claim 1 , wherein an end of the stirring blade is located below a height position of an upper end of the hot air port.

9. A fuel supply unit that supplies the biomass to the inside of the furnace body; a second sensor for detecting the height of an upper surface of the biomass layer; a control device that controls the fuel supply unit based on a detection result of the second sensor; Further equipped with A hot air port through which the hot air from the hot air unit flows into the inside of the furnace body is arranged on the inner surface of the furnace body, The carbonization furnace according to claim 1 , wherein the control device, when driving the hot air unit, sets the height position of an upper surface of the biomass accumulated in the furnace body to be higher than the height position of a lower end of the hot air port.

10. The carbonization furnace of claim 9, wherein the control device further sets the height position of the upper surface of the biomass accumulated in the furnace body on the radially outer side of the hot air port below the height position of the upper end of the hot air port when driving the hot air unit.

11. The furnace further includes a fuel supply unit that supplies the biomass to the inside of the furnace body, A hot air port and a supply port are arranged on the inner surface of the furnace body, The hot air from the hot air unit flows into the inside of the furnace body through the hot air port, The biomass is supplied from the supply port into the inside of the furnace body, The carbonization furnace according to claim 1 , wherein the supply port is located above the hot air port and at the same position as the hot air port in the circumferential direction.

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