Carbonization furnace and carbonization apparatus

Abstract

To provide a carbonization apparatus capable of suppressing reduction in production efficiency of smoked charcoal and properly implementing steady operation of a carbonization furnace.SOLUTION: A control device for a carbonization furnace that produces smoked charcoal by combusting biomass controls a fuel supply unit that supplies biomass to a furnace body and an air supply part that supplies air to the interior of the furnace body. The control device has a steady operation mode and a cleaning mode. In the steady operation mode, air is supplied to the interior of the furnace body and the supplied biomass is combusted. In the cleaning mode, air is supplied to the interior of the furnace body and soot accumulated on the inner peripheral surface of the furnace body is removed.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

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

[0003] When biomass fuel is burned, it produces soot such as graphite. A part of the produced soot accumulates on the inner wall of the furnace. As the combustion of the biomass fuel progresses, the soot accumulation layer becomes thicker. [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, as the soot deposition layer thickens, the internal space inside the deposition layer narrows, making it difficult for externally supplied biomass fuel and gases generated by the combustion of biomass fuel to pass through. This may result in a decrease in the efficiency of charcoal production or in the inability of the carbonization furnace to operate normally.

[0006] In view of the above circumstances, the present invention aims to suppress a decrease in the production efficiency of charcoal and to normally perform steady-state operation of a carbonization furnace. [Means for solving the problem]

[0007] In order to achieve the above object, a carbonization furnace according to one aspect of the present invention burns biomass to produce smoky charcoal. The carbonization furnace comprises a furnace body, a fuel supply unit, an air intake section, and a control device. The furnace body accommodates the biomass. The fuel supply unit supplies the biomass to the furnace body. The air intake section supplies air to the inside of the furnace body. The control device controls the fuel supply unit and the air intake section. The control device has a steady operation mode and a cleaning mode. In the steady operation mode, air is supplied to the inside of the furnace body and the supplied biomass is combusted. In the cleaning mode, air is supplied to the inside of the furnace body and soot accumulated on the inner circumferential surface of the furnace body is removed.

[0008] In order to achieve the above object, a carbonization apparatus according to one aspect of the present invention includes the above-mentioned carbonization furnace.

[0009] Further features and advantages of the present invention will become apparent from the following embodiments. Effect of the Invention

[0010] According to the present invention, the decrease in the efficiency of charcoal production can be suppressed, and the steady operation of the carbonization furnace can be normally performed. [Brief description of the drawings]

[0011] [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 [Diagram 3] A time chart showing an example of changes in the total air supply volume and the biomass supply rate in each operation mode of the control device. [Figure 4] A flowchart for explaining an example of a process for producing smoked charcoal [Diagram 5] Time chart showing an example of charcoal production in a carbonizer DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] 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."

[0014] <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 non-combustible level. In FIG. 1, the rough dashed line fa indicates the upper surface of the deposition layer of the biomass B in the ignition process of the biomass B described later. The solid line fb indicates the upper surface of the deposition layer of the biomass B (or smoky charcoal C) in the temperature rise control and steady operation process in the furnace body 1 described later.

[0015] 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.

[0016] 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.

[0017] That is, the water sprinkler device 402 is disposed in at least one of the charcoal conveying device 300 and the filling device 400. In this way, smoldering or ignited charcoal C can be extinguished by sprinkling water. Therefore, it is possible to prevent a fire caused by the combustion of the charcoal C filled in the bag 401. In addition, by sprinkling water on the charcoal C discharged from the carbonization furnace 100, it is possible to extinguish the charcoal C without destroying its shape.

[0018] 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.

[0019] <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.

[0020] 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.

[0021] <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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] In this embodiment, four lower air intake ports 113 are arranged at equal intervals in the circumferential direction. However, this is not limited to the example, and the number of lower air intake ports 113 may be one or a multiple number other than four, and the multiple lower air intake ports 113 may be arranged at different intervals in the circumferential direction.

[0028] 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 gas generated by the combustion of the biomass B and an updraft of heated air. These include combustible fine particles such as graphite (hereinafter referred to as soot) and combustible gases. The space above the low-oxygen region of the furnace body 1 is a high-oxygen region with a high concentration of oxygen, in order to burn these particles 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.

[0029] 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.

[0030] 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.

[0031] Preferably, a bottom air supply port 133 is further disposed in the bottom 13. The bottom air supply port 133 is located on the upper surface of the bottom 13 and penetrates the bottom 13 in the up-down direction. The bottom air supply port 133 is connected to the air supply unit 115 via a valve 1331. The valve 1331 switches between opening and closing the air supply passage between the air supply unit 115 and the bottom air supply port 133 in response to the control of the control device 7. However, this example does not exclude a configuration in which the bottom air supply port 133 is not disposed in the bottom 13.

[0032] The rotary valve 14 is a discharge part connected to the discharge port 132, and is controlled by the control device 7 to discharge the smoky charcoal C in the furnace body 1 to the outside. For example, the rotary valve 14 changes the discharge speed of the contents (biomass B or smoky 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 the biomass B (or smoky charcoal C) from the discharge port 132. The rotor of the rotary valve 14 also discharges the smoky 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 smoky 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.

[0033] 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.

[0034] <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.

[0035] 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.

[0036] <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.

[0037] <2-4. Mixing unit 4> The stirring unit 4 is attached to the bottom 13 of the furnace body 1 and is rotatable around a 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. The stirring unit 4 has a shaft member 41, a stirring blade 42, a cone portion 43, and a drive portion 44.

[0038] 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.

[0039] The agitator blades 42 extend radially outward from the shaft member 41 with respect to the shaft member 41, and are rotatable around the shaft member 41. The ends (for example, the radially outer ends) of the agitator blades 42 face the inner surface of the cylindrical portion 11 of the furnace body 1 in the radial direction with a small gap therebetween. In this embodiment, four agitator 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 agitator blades 42 may be a single blade or a plurality other than four. Furthermore, the multiple agitator blades 42 may be arranged at equal intervals in the circumferential direction, or may be arranged at different intervals.

[0040] 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.

[0041] 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.

[0042] <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.

[0043] 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.

[0044] In the ignition 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, and 54 are disposed above the target height position of the upper surface fa of the deposition layer of biomass B.

[0045] In the temperature increasing process and normal operation of the furnace body 1, the first to third temperature sensors 51, 52, 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.

[0046] 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.

[0047] <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.

[0048] <2-7. Control device 7> The control device 7 controls each component 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 device 500. The control device 7 has a memory 71, an input unit 72, and a timing unit 73. The memory 71 is a non-transient storage medium. The input unit 72 accepts operation inputs from a user. The control device 7 controls the above-mentioned components and devices, for example, based on the programs and information stored in the memory 71, the operation inputs accepted by the input unit 72, and the detection results of the temperature sensor 5 and the upper temperature sensor 6. The timing unit 73, for example, times the current time or the period that has elapsed since a point specified by the input unit 72 or the like.

[0049] For example, as shown in FIG. 3, the control device 7 has a normal operation mode and a cleaning mode. FIG. 3 is a time chart showing an example of changes in the total air supply amount and the supply rate of biomass B in each operation mode of the control device 7. The "total air supply amount" in FIG. 3 is the total amount of air supplied from the air supply section 115 into the furnace body 1 through at least one of the lower air supply port 113, the upper air supply port 114, and the bottom air supply port 133. For example, in this embodiment, the air is supplied through the lower air supply port 113. The "supply rate" in FIG. 3 is the supply amount of biomass B per unit time from the fuel supply unit 3 into the furnace body 1. The points P2 to PE in FIG. 3 correspond to the points P2 to PE in FIG. 5, which will be described later. In FIG. 3, the modes in which ignition control and temperature rise control are performed are omitted.

[0050] In the steady operation mode, the control device 7 supplies air into the furnace body 1, combusts the supplied biomass B, and discharges the generated smoky charcoal C. In the steady operation mode, soot generated from the biomass B (or smoky charcoal C) accumulates on the inner circumferential surface of the furnace body 1 and further covers the temperature sensor 5 and the upper temperature sensor 6 protruding from the inner circumferential surface.

[0051] In the cleaning mode, the control device 7 supplies air into the furnace body 1 and removes soot accumulated on the inner peripheral surface of the furnace body 1. For example, in the cleaning mode, the control device 7 first stops the supply of air from the air supply section 115 into the furnace body 1, slows down the supply rate of biomass B compared to the normal operation mode or stops it, and discharges a predetermined amount or more of smoky coal C, as shown in P3a, P6a, and P9a in FIG. 3. Thereafter, the control device 7 slows down or stops the supply rate of biomass B and supplies air into the furnace body 1 in a state in which smoky coal C is discharged. As a result, in the cleaning mode, soot accumulated on the inner peripheral surface of the furnace body 1 is removed.

[0052] By implementing the cleaning mode, the soot accumulated on the inner peripheral surface of the furnace body 1 in the normal operation mode can be removed by combustion. Therefore, the inner space of the furnace body 1 is prevented from narrowing when viewed from the top and bottom, and the blockage of the inner space can be prevented. For example, the supply passage of the biomass B and the circulation passage of the gas generated by combustion can be prevented from narrowing, and the blockage of these passages can be prevented. In addition, the sensors (e.g., the temperature sensor 5, the upper temperature sensor 6) arranged inside the furnace body 1 can be prevented from being covered with a layer of accumulated soot, and thus erroneous detection by the sensors can be prevented. Therefore, the decrease in the production efficiency of the smoky charcoal C can be suppressed, and the normal operation of the carbonization furnace 100 can be performed normally.

[0053] Preferably, in the cleaning mode, the control device 7 stops the supply of the biomass B and discharges all of the charcoal C from the furnace body 1. This can prevent new soot from being generated in the cleaning mode. Therefore, new soot does not accumulate, and there is no need to burn the soot floating inside the furnace body 1. Therefore, in the cleaning mode, the soot accumulation layer can be removed efficiently and quickly.

[0054] However, this example does not exclude a configuration in which the supply of biomass B is not stopped in the cleaning mode, and a configuration in which all of the charcoal C in the furnace body 1 is not discharged in the cleaning mode. For example, the control device 7 may supply a small amount of biomass B to an extent that does not affect the removal of soot in the cleaning mode, or may discharge the charcoal C in the furnace body 1 to an extent that a small amount of charcoal C remains. By leaving a small amount of fuel (i.e., biomass B, charcoal C), the internal temperature of the furnace body 1 in the cleaning mode can be maintained at least at a predetermined temperature (for example, a temperature at which biomass B can spontaneously combust; such as 650°C).

[0055] Also, preferably, the control device 7 starts the cleaning mode when a predetermined first period L1 (e.g., several tens of hours) has elapsed since the start of the steady operation mode. In this way, the soot deposit layer in the furnace body 1 can be removed by the cleaning mode every time the first period L1 has elapsed. Since the soot deposit layer can be removed periodically, it is possible to more reliably suppress a decrease in the production efficiency of the smoked charcoal C, and the steady operation of the carbonization furnace 100 can be normally performed. However, the start of the cleaning mode is not limited to this example. For example, the control device 7 may start the cleaning mode in response to an operation input received by the input unit 72.

[0056] Also, preferably, the control device 7 ends the cleaning mode when a predetermined second period L2 (e.g., several tens of minutes) has elapsed since the start of the cleaning mode. Also, preferably, the control device 7 may end the cleaning mode when the internal temperature of the furnace body 1 falls below a predetermined value (e.g., 650°C). Then, the control device 7 resumes the steady operation mode. In this way, the carbonization furnace 100 can resume the steady operation mode, for example, at the timing when a predetermined amount (or the entire amount) of the deposited layer of soot has been removed. Also, the carbonization furnace 100 can resume the steady operation mode while maintaining the internal temperature of the furnace body 1 at about a desired temperature (e.g., a temperature at which the biomass B can spontaneously ignite and burn). Therefore, the carbonization furnace 100 can efficiently perform steady operation.

[0057] However, the end of the cleaning mode is not limited to this example. For example, the control device 7 may end the cleaning mode in response to an operation input received by the input unit 72. Alternatively, the control device 7 may end the cleaning mode in response to the detection result of the carbon dioxide sensor arranged in the furnace body 1. For example, in the cleaning mode, the detection value of the carbon dioxide sensor rises due to the combustion of soot, but then drops when the amount of soot decreases. The control device 7 may end the cleaning mode when the falling detection value of the carbon dioxide sensor falls below a predetermined value. Also, the cleaning mode may be ended when the detection temperature of the fourth temperature sensor 54 arranged at the top starts to drop.

[0058] More preferably, the control device 7 further has a preliminary combustion mode as shown in Fig. 3. In the preliminary combustion mode, the control device 7 supplies the biomass B into the furnace body 1 at a second supply rate lower than the first supply rate in the steady operation mode during a third period L3 (e.g., several tens of seconds) before the steady operation mode is resumed.

[0059] When the cleaning mode ends, the control device 7 executes the preliminary combustion mode and then resumes the normal operation mode. In this way, when the normal operation mode is resumed, it is possible to prevent the internal temperature of the furnace body 1 from rising rapidly and becoming higher than the target temperature due to the rapid combustion of the biomass B. For example, the cleaning mode causes the oxygen concentration in the lower part (e.g., low-oxygen region) of the furnace body 1 to be higher than when the normal operation mode is performed. Therefore, by consuming oxygen in advance by burning a small amount of biomass B through the execution of the preliminary combustion mode, it is possible to make the oxygen concentration in the lower part of the furnace body 1 an appropriate concentration. Therefore, when the normal operation mode is resumed, it is possible to prevent the biomass B from burning rapidly and to prevent the biomass B from burning at a temperature that is too high compared to the target temperature of the normal operation mode. If the combustion temperature of the biomass B is too high, the amount of soot generated increases and the yield of the smoky charcoal C that can be produced decreases.

[0060] In addition, with some types of biomass B, such as rice husks and straw, there is a risk that unintended impurities such as crystalline silica may be generated if the biomass B is burned at too high a temperature. Therefore, by implementing the pre-combustion mode, the generation of such impurities can be prevented.

[0061] Furthermore, when the control device 7 supplies the biomass B into the furnace body 1, the upper surfaces fa and fb of the biomass deposition layer are positioned below the lower air supply port 113. This makes it possible to prevent the gas generated by the combustion of the biomass B and the burnt biomass B from flowing back into the lower air supply port 113. It is also possible to prevent the biomass B from burning at an excessively high temperature locally. This makes it possible to prevent unintended impurities such as crystalline silica from being generated locally.

[0062] Preferably, at least one of the lower air intakes 113 sends out an airflow in a direction intersecting the radial direction when viewed from the top-bottom direction. For example, in FIG. 2, all of the four lower air intakes 113 arranged in the circumferential direction send out airflow in the above-mentioned direction. In this way, a swirling airflow can be formed that flows along the inner circumferential surface of the furnace body 1 (specifically, the surface of the soot accumulation layer). The swirling airflow can increase the oxygen concentration near the surface of the soot, allowing the soot to be burned efficiently.

[0063] More preferably, at least one of the lower air supply ports 113 has the airflow directed obliquely upward. In this way, the above-mentioned swirling airflow can be made into a spiral airflow that swirls upward. The spiral airflow makes it easier for the soot combustion range to spread upward. In addition, gases such as carbon dioxide generated by the combustion of soot can be moved upward inside the furnace body 1. This prevents the gases from stagnating in the lower part of the furnace body 1, making it easier to increase the oxygen concentration. This makes it possible to burn soot more efficiently. Furthermore, it makes it easier to exhaust gases such as carbon dioxide from the exhaust port 121 on the upper side of the furnace body 1.

[0064] However, the above examples do not exclude a configuration in which the direction in which the airflow is discharged from all lower air intake ports 113 is not obliquely upward, and do not exclude a configuration in which the direction in which the airflow is discharged from all lower air intake ports 113 is not a direction that intersects the radial direction when viewed from the up-down direction. For example, each lower air intake port 113 may discharge an airflow in a direction perpendicular to the up-down direction and intersects the radial direction. Alternatively, each lower air intake port 113 may discharge an airflow radially inward.

[0065] Moreover, 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. Furthermore, a part of the control performed by the control device 7 may be performed manually.

[0066] <3. Example of producing charcoal C by burning biomass B> Next, a manufacturing example of smoked charcoal C will be described with reference to Fig. 3 to Fig. 5. Fig. 4 is a flow chart for explaining an example of a manufacturing process of smoked charcoal C. Fig. 5 is a time chart showing a manufacturing example of smoked charcoal C in the carbonization device 500. Each step shown in Fig. 3 to Fig. 5 is performed based on the control of the control device 7. Also, in Fig. 5, each time point P0 to PE is arranged at equal intervals, but the width of each interval is unrelated to the actual period in each control mode.

[0067] First, between time points P0 and P1 in Fig. 5, the biomass B in the furnace body 1 is ignited by the hot air unit 2 (step S101). For example, the biomass B is supplied up to about the upper surface fa in Fig. 1 and piled up in the furnace body 1. After air supply is started at the lower air supply port 113, the hot air unit 2 starts to be driven and the biomass B is ignited by the hot air flowing into the furnace body 1. Then, the stirring unit 4 starts to be driven, and the ignition range of the biomass B is expanded by stirring. The stirring unit 4 may be driven continuously after being driven intermittently, or may be driven continuously from the beginning.

[0068] Next, it is determined whether the temperature rise rate ΔT1 of the first temperature sensor 51 is equal to or greater than a predetermined value ΔT1s (step S102). At this time, it is preferably determined whether the duration t1 of ΔT1≧ΔT1s in the first temperature sensor 51 is equal to or greater than a predetermined period t1s. 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 point and is the closest to the upper surface fa in the vertical direction. The temperature rise rate ΔT1 is the rise rate [°C / sec] of the detected temperature T1 per unit time in the first temperature sensor 51 in step S102, and is, for example, several [°C / sec]. The predetermined value ΔT1s is a threshold value of the temperature rise rate ΔT1, and is set to, for example, 5 [°C / sec] or more. The predetermined period t1s is a threshold value of the duration t1, and is, for example, several tens [sec]. By determining whether or not ignition has been successful within the duration t1, erroneous determination of the detected temperature due to noise during temperature detection can be suppressed.

[0069] If ΔT1 < ΔT1s (preferably t1 < t1s) (NO in step S102), 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 S103), and the production of the charcoal C ends. Alternatively, when NO in step S102, steps S101 and S102 may be executed again. At this time, when the determination of NO in step S102 continues to reach a predetermined number of times, it is determined that the ignition has failed, and the carbonization device 500 is stopped. Also, when it is determined that the 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.

[0070] On the other hand, if ΔT1 ≥ ΔT1s (preferably t1 ≥ t1s) (YES in step S102), it is determined that the initial ignition of the biomass B has succeeded, and the continuous supply of the biomass B into the furnace body 1 and the operations of the rotary valve 14 and the charcoal conveying device 300 are started (step S104).

[0071] Next, it is determined whether or not the detected temperature T2 of the first temperature sensor 51 is equal to or higher than a predetermined value T2s (step S105). At this time, preferably, it is determined whether or not the duration t2 during which T2 ≥ T2s by the first temperature sensor 51 is equal to or longer than a predetermined period t2s. Note that the first temperature sensor 51 is an example of a temperature sensor that is below the upper surface fa of the deposited layer of the biomass B among the temperature sensors 5 at this point in time and is the closest temperature sensor to the upper surface fa in the vertical direction. Also, the detected temperature T2 is the detection result by the first temperature sensor 51 in step S105. The predetermined value T2s is a threshold value of the detected temperature T2, for example, 900 [°C]. The predetermined period t2s is a threshold value of the duration t2, for example, 1 [sec] or more. By making the determination based on the duration t2, false determination of the detected temperature T2 due to noise at the time of temperature detection can be suppressed.

[0072] If T2≧T2s (preferably t2≧t2s) (YES in step S105), the hot air unit 2 is stopped (step S106) at time point P1 in Fig. 5. This ends the process of igniting biomass B using the hot air unit 2.

[0073] 5, air supply through the upper air supply port 114 is started (step S107). Then, biomass B is continuously supplied into the furnace body 1 at a supply speed such that the upper surface of the piled layer of biomass B reaches the upper surface fb in FIG. 1 (step S108).

[0074] Next, it is determined whether the detected temperature T3 of the first to fourth temperature sensors 51, 52, 53, 54 is equal to or greater than the predetermined value T3s (step S109). At this time, it is preferably determined whether the duration t3 of T3≧T3s is equal to or greater than the predetermined period t3s in the first to fourth temperature sensors 51, 52, 53, 54. The detected temperature T3 is the detection result of the first to fourth temperature sensors 51, 52, 53, 54 in step S109, and includes all the detected temperatures of the first to fourth temperature sensors 51, 52, 53, 54, for example. The predetermined value T3s is a threshold value of the detected temperature T3, and is, for example, 750° 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.

[0075] 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 T3 ≧ T3s (preferably t3 ≧ ts) (YES in step S109), the air supply to the lower air supply port 113 is stopped (step S110). 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.

[0076] Then, the internal temperature of the furnace body 1 is adjusted to a target temperature (for example, 900 to 1000° C.) by adjusting the supply rate of the biomass B in the fuel supply device 200 (step S111).

[0077] 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 a predetermined value T4s (step S112). 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 S112, and includes, for example, all the detected temperatures of the first to fourth temperature sensors 51, 52, 53, 54. The predetermined value T4s is a threshold value of the detected temperature T4, and is, for example, 1000° C. The predetermined period t4s is a threshold value of the duration t4, and is, for example, 1 sec or more. By determining based on the duration t4, it is possible to suppress erroneous determination of the detected temperature T4 due to noise during temperature detection.

[0078] If T4≧T4s (preferably t4≧t4s) (YES in step S112), the steady operation mode of the carbonization furnace 100 is started (step S113), as at points P2, P5, and P8 in Figures 3 and 5, and smoky charcoal C is continuously produced.

[0079] Next, it is determined whether or not the first period L1 (see FIG. 3) has elapsed since the start of the steady operation mode (step S114). If the first period L1 has elapsed (YES in step S114), the cleaning mode is started and the air supply through the upper air supply port 114 is stopped (step S115), as at time points P3, P6, and P9 in FIG. 3 and FIG. 5. Note that the air supply through the lower air supply port 113 remains stopped. Then, the supply of biomass B is stopped, and all of the smoky coal C in the furnace body 1 is discharged (step S116).

[0080] After all the smoky charcoal C is discharged, air supply is started through the lower air supply port 113 (step S117), as shown at times P3a, P6a, and P9a in Fig. 3 and Fig. 5. Air supply at high temperatures in the furnace body 1 burns soot accumulated on the inner peripheral surface of the furnace body 1 during the steady operation mode (step S118). This makes it possible to remove the accumulated soot. Note that air supply in the cleaning mode may be performed through the bottom air supply port 133 formed in the bottom 13 of the furnace body 1.

[0081] Next, it is determined whether the detected temperature T5 of the temperature sensor 5 (for example, the first to fourth temperature sensors 51, 52, 53, 54) is equal to or lower than a predetermined value T5s (step S119). At this time, it is preferably determined whether the duration t5 of T5≧T5s is equal to or longer than the predetermined period t5s in the first to fourth temperature sensors 51, 52, 53, 54. Note that the detected temperature T5 is the detection result in the first to fourth temperature sensors 51, 52, 53, 54 in step S119, and includes, for example, all the detected temperatures of the first to fourth temperature sensors 51, 52, 53, 54. The predetermined value T5s is a threshold value of the detected temperature T5, and is, for example, 650 to 700° C. The predetermined period t5s is a threshold value of the duration t5, and is, for example, 1 sec or longer. 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.

[0082] In step S119, it may be determined whether or not the second period L2 has elapsed since the start of the cleaning mode. In this case, when the second period L2 has elapsed (that is, YES in step S119), the process proceeds to step S120.

[0083] If T5≧T5s (preferably t5≧t5s) (YES in step S119), it is determined whether or not to stop the production of charcoal C (step S120). This determination is made based on, for example, the completion of the supply of fuel (i.e., biomass B) stored in the fuel supply device 200, the receipt of an operation input to stop operation at the input unit 72 of the control device 7, etc.

[0084] If the production of charcoal C is not stopped (NO in step S120), the preliminary combustion mode is started, as at time points P4 and P7 in Fig. 3 and Fig. 5. For example, biomass B is supplied into the furnace body 1 at a supply speed slower than that during normal operation, and the stirring unit 4 is driven (step S121). This causes the biomass B to ignite by natural combustion. At this time, the hot air unit 2 may be driven to ignite the biomass B with hot air. Then, the biomass B is combusted by the combustion heat. By implementing the preliminary combustion mode, it is possible to prevent the biomass B from burning rapidly under high oxygen concentration and high temperature conditions.

[0085] Next, it is determined whether or not a third period L3 (e.g., several tens of seconds; see FIG. 3) has elapsed since the start of the preliminary combustion mode (step S122). If the third period L3 has elapsed (YES in step S122), the process returns to step S113. That is, the continuous supply of the fuel supply unit 3, and the continuous operation of the agitation unit 4, the rotary valve 14, and the coal transport device 300 are started in the steady operation mode.

[0086] On the other hand, when the production of smoky charcoal C is stopped (YES in step S116), the operation of the carbonization device 500 and the carbonization furnace 100 is stopped, and the process of Fig. 3 to Fig. 5 is ended (see time PE in Fig. 3 and Fig. 5). By removing soot in the cleaning mode before stopping the production of smoky charcoal C, it is possible to prevent the soot from adhering to the inner circumferential surface of the furnace body 1. Furthermore, the carbonization furnace 100 of the carbonization device 500 can be operated normally at the next operation without being affected by the accumulation of soot.

[0087] <4. Notes> The above describes the embodiments of the present invention. Note that the above embodiments are merely examples, 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.

[0088] <5. Summary> The embodiments described thus far will be summarized below.

[0089] For example, the carbonization furnace 100 disclosed herein may include: A carbonization furnace 100 for producing charcoal C by burning biomass B, A furnace body 1 that accommodates the biomass B; A fuel supply unit 3 that supplies the biomass B to the furnace body 1; An air supply section 115 for supplying air into the inside of the furnace body 1; A control device 7 for controlling the fuel supply unit 3 and the air supply section 115; Equipped with The control device 7 is A steady operation mode in which air is supplied to the inside of the furnace body 1 and the supplied biomass B is combusted; a cleaning mode in which air is supplied into the inside of the furnace body 1 to remove soot accumulated on the inner circumferential surface of the furnace body 1; The configuration has the above structure (first configuration).

[0090] The carbonization furnace 100 of the first configuration is as follows: The control device 7 may be configured (second configuration) to supply air into the furnace body 1 in the cleaning mode while the supply rate of the biomass B is slower than in the steady operation mode or is stopped.

[0091] The carbonization furnace 100 having the first or second configuration described above has the following features: Further provided is a discharge part 14 for discharging the smoky charcoal C in the furnace body 1 to the outside, The control device 7 is Controlling the discharge unit 14; In the cleaning mode, a configuration (third configuration) in which air is supplied into the furnace body 1 while the smoky coal C is being discharged may also be used.

[0092] Any of the first to third carbonization furnaces 100 described above includes: The control device 7 may be configured to stop the supply of the biomass B and discharge all of the smoky coal C from within the furnace body 1 in the cleaning mode (fourth configuration).

[0093] In addition, the carbonization furnace 100 having any one of the first to fourth configurations described above has the following features: The control device 7 may be configured to start the cleaning mode when a predetermined first period L1 has elapsed since the start of the steady operation mode (a fifth configuration).

[0094] In addition, the carbonization furnace 100 having any one of the first to fifth configurations described above has the following features: The control device 7 may be configured (sixth configuration) to terminate the cleaning mode and resume the steady operation mode when a predetermined second period L2 has elapsed since the start of the cleaning mode or when the internal temperature of the furnace body 1 falls below a predetermined value.

[0095] Moreover, the carbonization furnace 100 having the sixth configuration has the following features: The control device 7 further has a preliminary combustion mode in which the biomass B is supplied into the furnace body 1 at a second supply rate lower than the first supply rate in the steady operation mode during a third period L3 before the steady operation mode is resumed, When the cleaning mode ends, the preliminary combustion mode may be performed, and then the steady operation mode may be resumed (seventh configuration).

[0096] In addition, the carbonization furnace 100 having any one of the first to seventh configurations described above has the following features: Air inlets 113, 133 are arranged on at least one of the inner peripheral surface (i.e., the radially inner surface of the cylindrical portion 11) and the bottom surface (i.e., the upper surface of the bottom 13) of the furnace body 1, The control device 7 may be configured to cause the airflow supplied from the air supply part 115 to flow into the inside of the furnace body 1 from the air supply ports 113, 133 in the cleaning mode (eighth configuration).

[0097] In addition, the carbonization furnace 100 having any one of the first to eighth configurations described above has the following features: An air inlet 113 is arranged on the inner peripheral surface of the lower part of the furnace body 1, At the air inlet 113, the airflow supplied from the air inlet 115 flows into the inside of the furnace body 1, The control device 7 may be configured so that the upper surface of the pile layer of the biomass B is located below the air supply port 113 (ninth configuration).

[0098] Moreover, the carbonization furnace 100 having the ninth configuration is as follows: The air supply port 113 may be one or more. At least one of the air supply ports 113 may be configured to send out the airflow in a direction intersecting the radial direction when viewed from the top-bottom direction (tenth configuration).

[0099] Moreover, the carbonization furnace 100 having the tenth configuration has the following features: In at least any one of the air supply ports 113, the direction in which the airflow is discharged may be further configured to face obliquely upward (eleventh configuration).

[0100] The carbonization apparatus 500 disclosed herein comprises: The carbonization furnace 100 has any one of the first to eleventh configurations (twelfth configuration).

[0101] Moreover, the carbonization apparatus 500 having the twelfth configuration has the following features: A charcoal conveying device 300 for conveying the smoky charcoal C discharged from the carbonization furnace 100; A filling device 400 that fills the transported smoked charcoal C into a storage container 401; A water sprinkler device 402 capable of sprinkling water on the charcoal C; Equipped with The sprinkler device 402 may be configured to be disposed in at least one of the charcoal conveying device 300 and the filling device 400 (thirteenth configuration). [Explanation of symbols]

[0102] 1...furnace body, 11...tube section, 111...hot air port, 112...supply port, 113...lower air inlet, 1131...valve, 114...upper air inlet, 1141...valve, 115...air inlet section, 12...lid section, 121...exhaust port, 13...bottom section, 131...central opening, 132...discharge port, 133...bottom air inlet, 1331...valve, 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, Description of the Drawings 41...shaft member, 42...mixing blade, 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, 73...timer 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 shaft, B...biomass, C...smoked charcoal

Claims

1. A carbonization furnace for burning biomass to produce charcoal, A furnace body that accommodates the biomass; A fuel supply unit for supplying the biomass to the furnace body; An air supply section that supplies air to the inside of the furnace body; a control device for controlling the fuel supply unit and the air supply section; Equipped with The control device includes: A steady operation mode in which air is supplied to the inside of the furnace body and the supplied biomass is combusted; a cleaning mode in which air is supplied into the inside of the furnace body to remove soot accumulated on the inner circumferential surface of the furnace body; A carbonization furnace having a

2. The carbonization furnace according to claim 1 , wherein in the cleaning mode, the control device supplies air into the inside of the furnace body while slowing down the supply rate of the biomass compared to the steady operation mode or stopping the supply rate of the biomass.

3. Further includes a discharge part for discharging the charcoal in the furnace body to the outside, The control device includes: Controlling the discharge section; The carbonization furnace according to claim 1 , wherein in the cleaning mode, air is supplied into the furnace body while the charcoal is being discharged.

4. The carbonization furnace according to claim 1 , wherein the control device, in the cleaning mode, stops the supply of the biomass and discharges all of the smoky charcoal from within the furnace body.

5. The carbonization furnace according to claim 1 , wherein the control device starts the cleaning mode when a predetermined first period has elapsed since the start of the steady operation mode.

6. The carbonization furnace according to claim 1 , wherein the control device terminates the cleaning mode and resumes the steady operation mode when a predetermined second period has elapsed since the start of the cleaning mode or when the internal temperature of the furnace body falls below a predetermined value.

7. The control device further has a preliminary combustion mode in which the biomass is supplied into the furnace body at a second supply rate that is lower than the first supply rate in the steady operation mode during a third period before the steady operation mode is resumed; The carbonization furnace according to claim 6 , wherein when the cleaning mode is completed, the preliminary combustion mode is performed, and then the steady operation mode is resumed.

8. An air inlet is arranged on at least one of the inner circumferential surface and the bottom surface of the furnace body, The carbonization furnace according to claim 1 , wherein in the cleaning mode, the control device causes the airflow supplied from the air supply unit to flow from the air supply port into the inside of the furnace body.

9. An air inlet is arranged on the inner peripheral surface of the lower part of the furnace body, At the air inlet, the airflow supplied from the air inlet section flows into the inside of the furnace body, The carbonization furnace according to claim 1 , wherein the control device positions an upper surface of the biomass pile layer below the air inlet.

10. The air intake port may be one or more, The carbonization furnace according to claim 9 , wherein at least one of the air inlets delivers the airflow in a direction intersecting a radial direction when viewed from above and below.

11. The carbonization furnace according to claim 10 , wherein the direction in which the airflow is discharged from at least any of the air supply ports is further directed obliquely upward.

12. A carbonization apparatus comprising the carbonization furnace according to any one of claims 1 to 11.

13. A charcoal conveying device for conveying the smoky charcoal discharged from the carbonization furnace; A filling device that fills the transported smoked charcoal into a storage container; A water sprinkler device capable of sprinkling water on the charcoal; Equipped with The carbonization apparatus according to claim 12 , wherein the water sprinkler device is disposed in at least one of the charcoal conveying device and the filling device.

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