Carbonization furnace and control method thereof

Abstract

To provide a carbonization furnace capable of improving energy efficiency by using a combustible exhaust gas discharged from a carbonization furnace.SOLUTION: A carbonization furnace 1A is assembled with a container 5 accommodating a carbonization target W for conducting carbonization, a recirculation pipe 8d for taking the exhaust gas from the inside of the container 5 out from a taking-out port 8a and for feeding the exhaust gas to the inside of the container 5 again from a re-feeding port 8b, and a re-discharge pipe 7 for taking the exhaust gas out from the inside of the container 5 via a re-discharging port 7a provided near the re-feeding port 8b and discharging it to the outside of the container 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a carbonization furnace and a control method thereof. [Background technology]

[0002] It is known to crush organic matter such as wood and carbonize it (Patent Documents 1 and 2). Patent Document 1 describes that the dry distillation gas generated in a carbonization unit is treated in a gas combustion treatment unit and then released into the atmosphere. Patent Document 2 describes that the dry distillation gas generated in a carbonization furnace is rendered harmless by a deodorizing and harmless combustion device and a tertiary combustion device and then released into the atmosphere. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 10-128294 (Fig. 2) [Patent Document 2] JP 2009-19156 A (Fig. 1) Summary of the Invention [Problem to be solved by the invention]

[0004] However, as described in the above-mentioned patent documents, rather than incinerating the combustible gases such as carbon monoxide and hydrogen contained in the exhaust gas (distillation gas) emitted from the carbonization furnace, from the perspective of improving energy efficiency, it is desirable to consume them within the carbonization furnace equipment and recover them as energy as much as possible without releasing them into the atmosphere.

[0005] Furthermore, the above-mentioned patent documents require catalyst equipment, auxiliary fuel supply, combustion equipment, etc., and the auxiliary fuel is consumed as energy, which increases the cost of the equipment or reduces energy efficiency, resulting in problems that are factors that impair economic viability.

[0006] The present disclosure has been made in consideration of these circumstances, and aims to provide a carbonization furnace and a control method thereof that can improve energy efficiency by using combustible exhaust gas emitted from the carbonization furnace. [Means for solving the problem]

[0007] A carbonization furnace according to one embodiment of the present disclosure includes a container in which material to be carbonized is placed and carbonized, a recirculation flow path that extracts exhaust gas from the inside of the container through an outlet and re-introduces the exhaust gas into the container through a re-inlet, and a re-discharge flow path that extracts exhaust gas from the inside of the container through a re-discharge port provided near the re-inlet and discharges it to the outside of the container.

[0008] A method for controlling a carbonization furnace according to one embodiment of the present disclosure includes a recirculation process in which exhaust gas is extracted from the inside of a container in which material to be carbonized is housed and carbonized through an extraction outlet and the exhaust gas is re-introduced into the container through a re-inlet, and a re-discharge process in which exhaust gas is extracted from the inside of the container through a re-discharge outlet provided near the re-inlet and discharged to the outside of the container. [Effects of the Invention]

[0009] The combustible exhaust gases emitted from the carbonization furnace can be used to improve energy efficiency. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram showing a vehicle equipped with a carbonization furnace according to a first embodiment of the present disclosure. [Figure 2] 2 is a front view showing the positional relationship between the re-insertion port and the re-ejection port of FIG. 1. FIG. [Figure 3] FIG. 3 is a front view showing a modification of FIG. 2. [Figure 4] FIG. 3 is a front view showing another modified example of FIG. 2. [Figure 5] FIG. 2 is a schematic diagram showing a modified example of the configuration of FIG. [Figure 6] FIG. 10 is a schematic diagram showing a modified example of the re-discharge pipe. [Figure 7] FIG. 2 is an explanatory diagram showing the draft pressure of the chimney in the configuration of FIG. 1. [Figure 8] FIG. 7 is an explanatory diagram showing the draft pressure of the chimney in the configuration of FIG. 6. [Figure 9] FIG. 4 is a schematic configuration diagram showing a carbonization furnace according to a second embodiment of the present disclosure. [Figure 10] FIG. 10 is a schematic configuration diagram showing a vehicle equipped with a carbonization furnace according to a third embodiment of the present disclosure. [Figure 11] FIG. 11 is a cross-sectional view taken along the line AA in FIG. [Figure 12] FIG. 12 is a cross-sectional view showing a modification of FIG. [Figure 13] FIG. 10 is a schematic configuration diagram showing a vehicle equipped with a carbonization furnace according to a fourth embodiment of the present disclosure. [Figure 14] FIG. 14 is a cross-sectional view taken along the line AA in FIG. [Figure 15] 4 is a timing chart showing the timing of opening and closing a gate valve. [Figure 16] 16 is a timing chart showing a modification of FIG. 15. [Figure 17] FIG. 10 is a vertical cross-sectional view showing the periphery of a recirculation pipe according to a fifth embodiment of the present disclosure. [Figure 18] 18 is a view showing the porous member taken along the CC arrow in FIG. 17. [Figure 19] 18 is a view showing the porous member taken along the CC arrow in FIG. 17. [Figure 20] FIG. 10 is a longitudinal cross-sectional view showing a configuration in which an extension portion is provided in a recirculation pipe. [Figure 21] FIG. 21 is a perspective view showing a porous member used in the extension pipe of FIG. 20. [Figure 22] FIG. 10 is a schematic configuration diagram showing a vehicle equipped with a carbonization furnace according to a sixth embodiment of the present disclosure. [Figure 23] FIG. 23 is a vertical cross-sectional view showing the periphery of the re-insertion port of FIG. 22. [Figure 24] FIG. 23 is a schematic diagram showing a modified example of the configuration of FIG. 22. [Figure 25]FIG. 11 is a schematic configuration diagram showing a vehicle equipped with a carbonization furnace according to a seventh embodiment of the present disclosure. [Figure 26] FIG. 26 is a schematic diagram showing a modified example of the configuration of FIG. [Figure 27] FIG. 13 is a schematic diagram showing a vehicle equipped with a carbonization furnace according to an eighth embodiment of the present disclosure. [Figure 28] FIG. 28 is a schematic diagram showing a modified example of FIG. 27. [Figure 29] FIG. 13 is a schematic configuration diagram showing a vehicle equipped with a carbonization furnace according to a ninth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. [First embodiment] Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. A carbonization furnace 1A according to this embodiment is shown in Figure 1. The carbonization furnace of the present disclosure includes not only a carbonization furnace that produces biochar from biomass raw materials, but also a reactor that produces biofuel from biomass raw materials that has been carbonized to a lesser extent than biochar.

[0012] The carbonization furnace 1A is fixed to the loading platform 3a of the vehicle 3. The carbonization furnace 1A may be detachable from the loading platform 3a.

[0013] The carbonization furnace 1A includes a container 5 capable of forming an airtight space, and a feeding hopper 6 provided on the top of the container 5 and into which a material to be carbonized W, which is a biomass raw material, is fed. The biomass raw material is, for example, wood.

[0014] Inside the container 5, the material to be carbonized W is stacked in order from the bottom up. An ignition unit (not shown) is provided at the bottom (near the bottom) of the container 5. The ignition unit has a burner inserted through one or more insertion openings provided on the side wall surface of the container 5 near the bottom of the container 5. By igniting the material to be carbonized W with the burner, carbonization progresses from the bottom of the material to be carbonized W stacked inside the container 5.

[0015] Carbonizing air A1 is supplied into the container 5. The flow rate of the carbonizing air A1 is adjusted by a flow control valve 11 controlled by a control unit (not shown). The inside of the container 5 is kept in an oxygen-deficient state with an air ratio of, for example, about 0.6 to 0.7, which causes partial combustion of the material to be carbonized W and promotes carbonization. The carbonizing air A1 may be supplied, for example, to the upper part of the container 5 (for example, a gas layer filled with gas). In this case, by supplying the carbonizing air A1 to the upper part of the container 5, the air ratio decreases from the top to the bottom of the container 5. Specifically, the carbonizing air A1 is consumed by combustion in the combustion region in the container 5 described below, and the air ratio below the combustion region is lower than that above. Therefore, carbonization of the material to be carbonized W can be effectively promoted in the lower part of the container 5 where the air ratio is lower. However, this is not limited to this, and as described below, a portion of the carbonizing air A1 may be supplied from the bottom of the container 5. By supplying the carbonization air A1 from above or below in an appropriate proportion, the carbonization of the material to be carbonized can be promoted more effectively.

[0016] Outside the container 5, there is provided a charcoal product removal section 12 that removes the charcoal product (carbonized material) W1 that has been carbonized in the container 5 from the container 5 and stores it.

[0017] A chimney 10 is installed on the loading platform 3a of the vehicle 3. The chimney 10 is erected vertically on the loading platform 3a. A re-discharge pipe (re-discharge flow path) 7 is provided between the chimney 10 and the container 5. The re-discharge pipe 7 is connected to the wall of the container 5 and has a re-discharge port 7a that opens into the container 5. The exhaust gas in the container 5 that flows in from the re-discharge port 7a passes through the re-discharge pipe 7 and is led to the chimney 10.

[0018] A recirculation pipe (recirculation flow path) 8 is provided below the re-discharge pipe 7. The recirculation pipe 8 has an outlet 8a connected to the wall of the container 5 and opening into the container 5, and a re-introduction port 8b connected to the wall of the container 5 above the outlet 8a and opening into the container 5. The exhaust gas in the container 5 that flows in from the outlet 8a passes through the recirculation pipe 8 and is re-introduced into the container 5 from the re-introduction port 8b. A GRF (Gas Recirculation Fan) 9 is provided in the recirculation pipe 8. The rotation speed of the GRF 9 is controlled by a control unit (not shown), thereby recirculating the exhaust gas at a desired flow rate.

[0019] The re-feeding port 8b is provided near the re-discharge port 7a. That is, the combustible exhaust gas re-feeded from the re-feeding port 8b is incinerated in the container 5, and the re-discharge port 7a is provided at a position close enough to allow the combustion gas generated by the incineration process to be preferentially removed.

[0020] The re-feeding port 8b is provided at a height position where the stacked materials W to be carbonized are present inside the container 5. The re-discharge port 7a is also provided at a height position where the stacked materials W to be carbonized are present inside the container 5.

[0021] 2 shows the positional relationship between the re-injection opening 8b and the re-ejection opening 7a. In the figure, the re-injection opening 8b and the re-ejection opening 7a are both circular and have the same area. However, the shapes and areas of the re-injection opening 8b and the re-ejection opening 7a are not limited to this. As shown in Figure 2, if the diameter (hydraulic diameter) of re-inlet 8b is D1, then distance L1 between center 8b1 of re-inlet 8b and center 7a1 of re-discharge outlet 7a is set to 10 times or less of D1. However, distance L1 may be 5 times or less, 3 times or less, or 2 times or less. Furthermore, distance L1 may be set close to 0, so that re-inlet 8b and re-discharge outlet 7a are positioned adjacent to each other.

[0022] The hydraulic diameter is the cross-sectional area of ​​the flow path divided by the wetted perimeter of the flow path cross section and multiplied by 4. If the flow path cross section is circular, it is the diameter of the circle, and if it is square, it is the length of one side of the square.

[0023] FIG. 3 shows an arrangement in which multiple (three in this figure) re-inlet ports 8b are arranged horizontally at a predetermined interval, and multiple (three in this figure) re-discharge ports 7a are arranged above each re-inlet port 8b in pairs at a predetermined interval. In FIG. 3, the re-inlet ports 8b and the re-discharge ports 7a are arranged in a square shape. In this arrangement, it is sufficient that the closest distance L1 between the re-inlet ports 8b and the re-discharge ports 7a is 10 times or less the hydraulic diameter D1 of the re-inlet port 8b. Therefore, the distance L2, which is greater than the closest distance L1, may be greater than or less than 10 times the hydraulic diameter D1 of the re-inlet port 8b.

[0024] Also, as shown in Figure 4, when multiple (four in this figure) re-discharge outlets 7a are provided for one re-inlet 8b, it is preferable to arrange them so that the center 7a1 of each re-discharge outlet 7a is at an equal distance L1 from the center 8b1 of the re-inlet 8b.

[0025] The control unit is composed of, for example, a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium, for example, in the form of a program. The CPU reads this program into RAM and executes information processing and arithmetic operations to realize various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0026] <Control method of carbonization furnace 1A> Next, a method for controlling the carbonization furnace 1A having the above-described configuration will be described. First, the material W to be carbonized is charged into the container 5 from the charging hopper 6. The material W charged into the container 5 from the charging hopper 6 is stacked from the bottom of the container 5. Once a predetermined amount of material W to be carbonized has been stacked, the material W located at the bottom of the container 5 is ignited using an ignition unit (not shown) provided at the bottom of the container. At this time, the air ratio inside the container 5 is set to an oxygen-deficient state, for example, about 0.6 to 0.7. As a result, the ignited material W undergoes partial combustion, and carbonization progresses from the bottom. At this time, the area where partial combustion is taking place is referred to as the combustion area. The combustion heat of the material W at the bottom is transferred to the material W above, and carbonization progresses sequentially from bottom to top.

[0027] After the carbonization of the carbonized material W progresses under conditions of oxygen deficiency after ignition, flammable gases such as carbon monoxide (CO) and hydrogen (H2) are generated. The generated flammable gas (exhaust gas) is extracted from the interior of the container 5 through the outlet 8a by the GRF 9, whose rotation speed is controlled by the control unit, and guided to the recirculation pipe 8. The flammable gas guided to the recirculation pipe 8 is re-introduced into the container 5 through the re-introduction port 8b. At this time, carbonization of the carbonized material W progresses within the container 5, and the flammable gas is released toward the carbonized material W, which has been heated to a high temperature of approximately 1000°C or several hundred degrees Celsius nearby. Because the ignition temperatures of carbon monoxide (CO) and hydrogen (H2) are approximately 500°C to 600°C, the flammable gas is ignited and burned by the heat of the carbonized material W, and the combustible components are incinerated. The post-combustion gas from which the combustible components have been burned is sucked out by the chimney effect of the chimney 10 from the re-discharge outlet 7a located near the re-injection inlet 8b, passes through the re-discharge pipe 7 and is discharged into the atmosphere (outside the container 5) via the chimney 10.

[0028] Carbonization proceeds through the above steps, and the carbonization process ends when all of the material W placed in the container 5 reaches the desired carbonization degree. After that, the temperature of the material W is lowered to a level at which it will not spontaneously combust even when exposed to air, and the material W inside the container 5 is then removed as product charcoal W1. In this way, the carbonization furnace 1A performs carbonization as a so-called batch process.

[0029] The above-described embodiment has the following advantages. The recirculation pipe 8 extracts combustible exhaust gas generated during carbonization from inside the container 5 and reintroduces the exhaust gas into the container 5 through the re-introduction port 8b. The combustible exhaust gas introduced into the container 5 through the re-introduction port 8b diffuses and burns within the container 5, which is maintained at approximately 1,000°C or a few hundred degrees Celsius close to this temperature, and is incinerated. Because the re-exhaust port 7a of the re-exhaust pipe 7 is located near the re-introduction port 8b, the re-introduced and incinerated burned gas is preferentially extracted through the re-exhaust port 7a and discharged to the outside of the container 5 via the re-exhaust pipe 7. In this way, by incinerating the combustible exhaust gas generated inside the container 5 of the carbonization furnace 1A inside the carbonization furnace 1A, environmental standards for exhaust gas discharged to the outside from the container 5 can be met, and the chemical energy of the exhaust gas can be recovered as thermal energy. This improves the energy efficiency of the carbonization furnace 1A.

[0030] Since the re-injection port 8b is provided at a position where the carbonized material W is present, the exhaust gas introduced from the re-injection port 8b penetrates between the carbonized material W while colliding with the carbonized material W. This promotes ignition and combustion of the combustible exhaust gas. In particular, by introducing the exhaust gas into a position where the carbonized material W is undergoing combustion or carbonization reaction, the ignition and combustion of the exhaust gas can be further promoted.

[0031] By positioning the center 7a1 of the re-discharge outlet 7a at a position less than 10 times the hydraulic diameter D1 of the re-injection outlet 8b from the center 8b1 of the re-injection outlet 8b and shortening the distance between the re-injection outlet 8b and the re-discharge outlet 7a, the exhaust gas introduced from the re-injection outlet 8b can be preferentially discharged from the re-discharge outlet 7a after being incinerated.

[0032] 2 and 3, one re-introduction port 8b corresponds to one re-discharge port 7a, so the distance between the re-introduction port 8b and the re-discharge port 7a can be appropriately determined. This allows the exhaust gas introduced from the re-introduction port 8b to be preferentially discharged from the re-discharge port 7a after being incinerated.

[0033] As shown in Fig. 4, since multiple re-discharge ports 7a are provided at equal distances from one re-injection port 8b, the distance between the re-injection port 8b and each re-discharge port 7a can be appropriately determined. This allows the post-combustion gas obtained by incinerating the exhaust gas introduced from the re-injection port 8b to be preferentially discharged from each re-discharge port 7a.

[0034] This embodiment can be modified as follows. As shown in FIG. 5 , an exhaust pipe 14 may be provided upstream of the GRF 9 in the recirculation pipe 8. The downstream end of the exhaust pipe 14 is connected to a chimney 10. The exhaust pipe 14 is provided with an IDF (Induced Draft Fan) 15 controlled by the control unit. In this way, instead of reintroducing the entire amount of exhaust gas into the container 5 through the recirculation pipe 8, only a portion of the exhaust gas may be reintroduced into the container 5. The exhaust pipe 14 may be provided downstream of the GRF 9 in the recirculation pipe 8. In this case, by providing a flow control valve or the like in the exhaust pipe 14 and controlling the opening degree of the flow control valve with the control unit, instead of reintroducing the entire amount of exhaust gas into the container 5 through the recirculation pipe 8, only a portion of the exhaust gas may be reintroduced into the container 5.

[0035] 6, an exhaust fan 17 may be provided in the re-discharge pipe 7. By providing the exhaust fan 17, the exhaust gas is forcibly exhausted to the outside of the container 5. This makes it possible to prevent the exhaust gas from flowing back through the re-discharge pipe 7 and re-entering the inside of the container 5.

[0036] As shown in Figure 1, when exhaust gas is discharged into the atmosphere using the stack effect (draft pressure) of the chimney 10 without installing an exhaust fan 17 in the re-discharge pipe 7, the chimney 10 cannot be made tall enough, and the draft pressure due to the stack effect may be insufficient. Specifically, as shown in the upper diagram of Figure 7, the draft pressure of the exhaust gas depends on the stack effect of the chimney 10, and sufficient buoyancy may not be obtained, as shown in the diagram. In this diagram, the inside of the vessel 5 is maintained at negative pressure, and a pressure drop occurs when the exhaust gas flows through the re-discharge pipe 7. In this case, there is a risk that the exhaust gas will flow back up the re-discharge pipe 7 and flow into the vessel 5 again.

[0037] In response to this, by increasing the pressure with the exhaust fan 17 as shown in FIG. 6, it is possible to assist the draft pressure generated by the chimney 10 as shown in FIG.

[0038] In FIG. 8, the pressure increase caused by the exhaust fan 17 is expressed by the following formula. Boosting pressure with exhaust fan 17 = Total draft pressure loss of stack 10 + Draft pressure loss in the re-exhaust pipe 7 before and after the exhaust fan 17 - draft pressure of vessel 5 In the above formula, the "total draft pressure loss of the chimney 10" is calculated as the value obtained by subtracting the absolute value of buoyancy (stack effect) from the draft loss inside the chimney 10, and is generally a negative value. The "draft pressure of the vessel 5" is generally a negative value, and therefore, combined with the minus sign immediately before it, has a positive effect on the pressure increase caused by the exhaust fan 17.

[0039] [Second embodiment] Next, a second embodiment of the present disclosure will be described. Figure 9 shows a carbonization furnace 1B according to this embodiment. While the carbonization furnace 1A of the first embodiment performed the carbonization process as a batch process, the carbonization furnace 1B of this embodiment differs in that it performs the carbonization process as a continuous process. Therefore, the following description will mainly focus on the differences from the first embodiment, and the same components will be denoted by the same reference numerals and their description will be omitted.

[0040] 9, the carbonization furnace 1B includes a cylindrical container 5 extending in the longitudinal direction x. A charging hopper 6 is provided at one end (left end) of the container 5.

[0041] A screw feeder 22 is provided in the container 5 as a conveying unit that continuously conveys the material to be carbonized W. The screw feeder 22 includes a rotating shaft 22a having an axis extending in the longitudinal direction x, and a spiral blade 22b attached to the rotating shaft 22a. The rotating shaft 22a is rotated by a driving unit (not shown). The rotation speed of the rotating shaft 22a may be variable and is controlled by a control unit.

[0042] The material to be carbonized W is charged from a charging hopper 6 and transported from the upstream side (left side) to the downstream side (right side) by a screw feeder 22. While being transported by the screw feeder 22, carbonization of the material to be carbonized W progresses inside the container 5.

[0043] A re-discharge pipe 7 is provided between the container 5 and the chimney 10. The re-discharge pipe 7 is provided with a re-discharge port 7a, similar to the first embodiment.

[0044] The container 5 is provided with a recirculation pipe 8. The recirculation pipe 8 is provided with a GRF 9. The recirculation pipe 8 has an outlet 8a and a re-inlet 8b, similar to the first embodiment.

[0045] The positional relationship between the re-inlet 8b and the re-ejection outlet 7a is the same as the positional relationship described with reference to FIGS.

[0046] The carbonization furnace 1B for carrying out the carbonization treatment as a continuous type as in this embodiment also provides the same effects as those of the first embodiment. In other words, by using a recirculation pipe 8 to re-introduce combustible exhaust gas into the container 5 for incineration, and then discharging the incinerated combustion gas from the container 5 to the outside using a re-exhaust pipe 7, it is possible to meet environmental standards for exhaust gas and recover the chemical energy contained in the exhaust gas as thermal energy.

[0047] [Third embodiment] Next, a third embodiment of the present disclosure will be described with reference to FIGS. 1 etc., in the configuration of the re-discharge pipe 7 and the recirculation pipe 8. Since other points are the same as those in the first embodiment, the same reference numerals are used and the description thereof will be omitted.

[0048] As shown in FIG. 10, the carbonization furnace 1C of this embodiment includes a re-discharge pipe 7 having a plurality of re-discharge ports 7a in the vertical direction, and a recirculation pipe 8 having a plurality of re-feed ports 8b in the vertical direction.

[0049] The re-discharge pipe 7 has three re-discharge ports 7a-1, 7a-2, and 7a-3 spaced apart in the vertical direction. The number of re-discharge ports 7a-1, 7a-2, and 7a-3 is not limited to three, but may be two or more.

[0050] The re-discharge ports 7a-1, 7a-2, and 7a-3 are connected to branch pipes 7-1, 7-2, and 7-3, respectively. The branch pipes 7-1, 7-2, and 7-3 are joined at a junction pipe 7-X. The downstream end of the junction pipe 7-X is connected to a chimney 10.

[0051] Gate valves (flow rate control valves) 7-1G, 7-2G, and 7-3G are provided on the branch pipes 7-1, 7-2, and 7-3, respectively. The gate valves 7-1V, 7-2V, and 7-3V may be controlled by a control unit or may be manually operated by an operator.

[0052] The recirculation pipe 8 has three re-introduction ports 8b-1, 8b-2, and 8b-3 spaced apart in the vertical direction. The number of re-introduction ports 8b-1, 8b-2, and 8b-3 is not limited to three, but may be two or more.

[0053] The re-injection ports 8b-1, 8b-2, and 8b-3 are connected to branch pipes 8-1, 8-2, and 8-3, respectively. Each branch pipe 8-1, 8-2, and 8-3 branches off from a single main pipe 8-X. The main pipe 8-X is equipped with a GRF 9, and an outlet 8a is provided at the upstream end of the main pipe 8-X.

[0054] The branch pipes 8-1, 8-2, and 8-3 are provided with gate valves (flow rate control valves) 8-1G, 8-2G, and 8-3G, respectively. The gate valves 8-1V, 8-2V, and 8-3V may be controlled by a control unit or may be manually operated by an operator.

[0055] The lower re-inlet port 8b-1 is located below the lower re-discharge port 7a-1, and the gate valves 8-1V and 7-1V are used in correspondence with each other. The middle re-inlet port 8b-2 is located below the middle re-discharge port 7a-2, and the gate valve 8-2V and the gate valve 7-2V are used correspondingly. The upper re-inlet port 8b-3 is located below the upper re-discharge port 7a-3, and the gate valves 8-3V and 7-3V are used correspondingly.

[0056] 11, the re-exhaust ports 7a-1, 7a-2, and 7a-3 and the re-injection ports 8b-1, 8b-2, and 8b-3 may be provided at the same height with a predetermined interval between them, thereby enabling the flammable exhaust gas to be treated uniformly in the horizontal direction.

[0057] The carbonization furnace 1C having the above-described configuration is used as follows. Carbonization of the material W in the container 5 progresses from bottom to top over time. In response to this, while the carbonization of the lower-level material W is progressing (time), the lower-level gate valves 8-1V and 7-1V are opened, and the other gate valves are closed. This allows the heat generated as the carbonization of the lower-level material W progresses to effectively treat flammable exhaust gas.

[0058] After the carbonization of the lower-stage carbonized material W is completed, and while the carbonization of the middle-stage carbonized material W is progressing (time), the middle-stage gate valves 8-2V and 7-2V are opened and the other gate valves are closed. This allows the heat generated as the carbonization of the middle-stage carbonized material W progresses to effectively treat flammable exhaust gas.

[0059] After the carbonization of the middle-stage carbonized material W is completed, and while the carbonization of the upper-stage carbonized material W is progressing (time), the upper-stage gate valves 8-3V and 7-3V are opened and the other gate valves are closed. This allows the heat generated as the carbonization of the upper-stage carbonized material W progresses to effectively treat flammable exhaust gas.

[0060] According to this embodiment, multiple re-discharge ports 7a-1, 7a-2, 7a-3 and re-injection ports 8b-1, 8b-2, 8b-3 are provided in the vertical direction, and by switching between the corresponding re-discharge ports 7a-1, 7a-2, 7a-3 and re-injection ports 8b-1, 8b-2, 8b-3 at each vertical position depending on the progress of carbonization of the carbonized material W in the container 5, flammable exhaust gas can be effectively treated.

[0061] This embodiment can be modified as shown in FIG. In Fig. 11, the re-ejection ports 7a-1, 7a-2, 7a-3 and the re-injection ports 8b-1, 8b-2, 8b-3 are aligned vertically, but as shown in Fig. 12, the re-ejection port 7a-1 and the re-injection port 8b-1 in the lower row may be horizontally shifted relative to the re-ejection port 7a-2 and the re-injection port 8b-2 in the middle row, resulting in a roughly staggered arrangement. Such an arrangement may also be provided between the middle and upper rows.

[0062] With the above configuration, the distance L3 between the re-introduction port 8b-1 in the lower stage and the re-discharge port 7a-1 in the lower stage can also be made equal to the distance L4 between the re-introduction port 7a-1 in the lower stage and the re-introduction port 8b-2 in the middle stage. By making the distances between the re-discharge ports 7a and 8b equal even between different stages (lower, middle, and upper stages) in this way, when, for example, post-combustion gas is re-introduced into the container 5 through the re-introduction port 8b-2 and incinerated, and then released to the outside of the container 5 through both the re-discharge ports 7a-1 and 7a-2 as described below, the amounts of post-combustion gas re-discharged from each of the re-discharge ports 7a-1 and 7a-2 can be planned to be equal, and the post-combustion gas can be effectively released to the outside of the container 5.

[0063] [Fourth embodiment] Next, a fourth embodiment of the present disclosure will be described with reference to FIG. The carbonization furnace 1D of this embodiment differs from the above-described third embodiment in that a temperature sensor is provided inside the container 5. The same components as those in the third embodiment are designated by the same reference numerals and will not be described again.

[0064] 13, three temperature sensors TX1, TX2, and TX3 are provided inside the container 5. The temperature sensors TX1, TX2, and TX3 are spaced apart in the vertical direction and are provided in positions facing the re-inlet ports 8b-1, 8b-2, and 8b-3, respectively. Note that the positions and number of the temperature sensors are not limited to three, and they are provided corresponding to the positions and number of the re-inlet ports 8b.

[0065] In this embodiment, the gate valves 7-1V, 7-2V, and 7-3V and the gate valves 8-1V, 8-2V, and 8-3V are motor-driven electrically operated valves.

[0066] As shown in FIG. 14, the gate valves are controlled synchronously as a set: lower stage G1 (gate valve 7-1V and gate valve 8-2V), middle stage G2 (gate valve 7-2V and gate valve 8-2V), and upper stage G3 (gate valve 7-3V and gate valve 8-3V).

[0067] 15 shows the opening degrees of the gate valves 7-1V, 7-2V, 7-3V, 8-1V, 8-2V, and 8-3V in relation to the measured values ​​of the temperature sensors TX1, TX2, and TX3. Note that in the figure, the gate valves are sometimes referred to as GB.

[0068] As shown in the upper part of Figure 15, the temperature history of the temperature sensor TX1 indicates that when the material to be carbonized W is ignited, its temperature rises rapidly and combustion begins. After that, pyrolysis progresses in the absence of oxygen, and the material is carbonized as a hot ember. The temperature change at this time is slow, and the temperature gradually decreases as carbonization progresses.

[0069] The opening degree of the gate valve is controlled in response to the above temperature changes. As shown in the lower part of Figure 15, when the control unit determines that the lower-stage carbonized material W has transitioned from the combustion process to the carbonization process based on the measurement value of the lower-stage temperature sensor TX1, the control unit commands the gate valves 7-1V and 8-1V of the lower stage G1 to open synchronously. Then, when the measurement value of the lower-stage temperature sensor TX1 falls below a predetermined value and the control unit determines that the lower-stage carbonized material W has been extinguished, the control unit commands the gate valves 7-1V and 8-1V of the lower stage G1 to close synchronously.

[0070] Similarly to the lower stage G1, when the control unit determines based on the measurement value of the middle stage temperature sensor TX2 that the material to be carbonized W in the middle stage has transitioned from the combustion process to the carbonization process, the control unit commands the gate valves 7-2V and 8-2V of the middle stage G2 to open synchronously. When the measurement value of the middle stage temperature sensor TX2 falls below a predetermined value and the control unit determines that the material to be carbonized W in the middle stage has been extinguished, the control unit commands the gate valves 7-2V and 8-2V of the middle stage G2 to close synchronously.

[0071] As with the lower stage G1 and middle stage G2, when the control unit determines based on the measurement value of the upper stage temperature sensor TX3 that the upper stage carbonized material W has transitioned from the combustion process to the carbonization process, the control unit commands the gate valves 7-3V and 8-3V of the upper stage G3 to open synchronously. Then, when the measurement value of the upper stage temperature sensor TX3 falls below a predetermined value and the control unit determines that the middle stage carbonized material W has been extinguished, the control unit commands the gate valves 7-3V and 8-3V of the upper stage G3 to close synchronously.

[0072] The above-described operational effects of this embodiment are in addition to the operational effects of the third embodiment, as follows. By providing temperature sensors TX1, TX2, and TX3 at positions corresponding to the re-injection ports 8b-1, 8b-2, and 8b-3, the control unit can accurately determine the progress of carbonization in the areas where the temperature sensors TX1, TX2, and TX3 are located based on the measurements of the temperature sensors TX1, TX2, and TX3. By controlling the gate valves 7-1V, 7-2V, 7-3V, 8-1V, 8-2V, and 8-3V based on the progress of carbonization, flammable exhaust gas can be effectively combusted with high precision.

[0073] The control of the gate valves 7-1V, 7-2V, 7-3V, 8-1V, 8-2V, and 8-3V can be modified as shown in FIG. As shown in Figure 16, when carbonization of the upper-level carbonized material W is completed and fire extinguishing is determined, the gate valve 8-1V of the re-inlet 8b-1 of the lower-level G1 is closed (thick solid line), while the gate valve 7-1V of the re-discharge outlet 7a-1 of the lower-level G1 is not closed but maintained at an intermediate opening (thin solid line). At the same time, when carbonization of the middle-level carbonized material begins, the gate valve 8-2V of the re-inlet 8b-2 of the middle-level G2 is opened, while the gate valve 7-2V of the re-discharge outlet 7a-2 of the middle-level G2 is not opened but maintained at an intermediate opening. This allows the flammable exhaust gas re-injected from the re-inlet 8b-2 of the middle-level G2 to be discharged through the upper and lower gate valves 7-1V and 7-2V. This allows the post-combustion gas from the incinerated flammable exhaust gas to be effectively discharged outside the container 5.

[0074] Similarly, the gate valve 7-2V of the re-discharge port 7a-2 of the middle stage G2 is controlled to maintain the intermediate opening even when the gate valve 8-2V of the re-injection port 8b-2 of the middle stage G2 is closed.

[0075] [Fifth embodiment] Next, a fifth embodiment of the present disclosure will be described. This embodiment can be applied to each of the first to fourth embodiments described above, and a specific configuration around the re-insertion port 8b will be described. Note that this embodiment can also be applied to the sixth and subsequent embodiments.

[0076] As shown in Fig. 17, the re-feeding port 8b opens flush with the wall of the container 5. At this time, a porous member 25 is provided to prevent the material to be carbonized W present inside the container 5 from entering the inside of the recirculation pipe 8. As the porous member 25, a porous plate as shown in Fig. 18 shown in the CC arrow view of Fig. 17, or a wire mesh as shown in Fig. 19, can be used. The mesh of the porous member 25 is selected to be smaller than the particles of the material to be carbonized W.

[0077] 20, an extension 8c may be provided on the recirculation pipe 8 so that the re-inlet 8b is located inside the container 5. The length L5 of the extension 8c protruding from the inner surface of the container 5 is, for example, several times the hydraulic diameter D1 of the recirculation pipe 8, and is set to be approximately the same as or shorter than the shortest distance L1 between the re-inlet 8b and the re-discharge outlet 7a in terms of their positional relationship, i.e., 10 times or less the hydraulic diameter D1 of the re-inlet 8b. A porous member 25 is provided at the tip of the extension 8c, as shown in FIG. 19. A porous member 25 may also be provided at the re-discharge outlet 7a.

[0078] By providing the re-injection port 8b inside the container 5, the exhaust gas can be injected into a high-temperature region from the re-injection port 8b, thereby facilitating ignition and combustion of the re-injected exhaust gas.

[0079] 21, the entire cylindrical wall of the extension 8c may be formed of a porous member (such as a porous plate or wire mesh), which allows the re-introduced exhaust gas to be diffused over a wide area within the material to be carbonized W, thereby enabling the exhaust gas to be effectively incinerated in a short time.

[0080] [Sixth embodiment] Next, a sixth embodiment of the present disclosure will be described with reference to FIG. 22 and other figures. The carbonization furnace 1E of this embodiment differs from the first embodiment described above in that an oxidizing agent supply unit is provided inside the container 5. The same components as those in the first embodiment are designated by the same reference numerals and will not be described again.

[0081] As shown in Figure 22, carbonization air supply units 27 that supply carbonization air to multiple positions are provided inside the container 5. The carbonization air supply units 27 are preferably provided at equal intervals so that air can be supplied evenly inside the container 5, but they can also be provided at unequal intervals depending on the degree of carbonization of the material W to be carbonized that is progressing inside the container 5. An oxidizer supply unit 28 that supplies air is provided at a position opposite the re-introduction port 8b.

[0082] As shown in FIG. 23, the distance L6 from the inner wall of the container 5 to the center of the oxidizer supply unit 28 is set to, for example, several times the hydraulic diameter D1 of the recirculation pipe 8, and is set to be approximately the same as or shorter than the closest distance L1 (see FIG. 2) in terms of the positional relationship between the re-introduction port 8b and the re-discharge port 7a, i.e., 10 times or less the hydraulic diameter D1 of the re-introduction port 8b.

[0083] According to this embodiment, by injecting air from the oxidizing agent supply unit 28 into the region into which the flammable exhaust gas is introduced, it is possible to promote ignition and combustion of the exhaust gas.

[0084] 24, when multiple stages of re-discharge ports 7a and re-injection ports 8b are provided in the vertical direction (see, for example, FIG. 10), oxidizer supply units 28-1, 28-2, 28-3 are provided corresponding to the re-injection ports 8b-1, 8b-2, 8b-3, respectively. The air flow rates of the oxidizer supply units 28-1, 28-2, 28-3 are controlled by air flow rate adjustment valves 28-1V, 28-2V, 28-3V operated by the control unit according to the progress of carbonization of the material to be carbonized W.

[0085] [Seventh embodiment] Next, a seventh embodiment of the present disclosure will be described with reference to FIG. The carbonization furnace 1F of this embodiment differs from the sixth embodiment (FIG. 22) in that a flow meter and an analyzer are provided in the recirculation pipe 8. The same components as those in the sixth embodiment are designated by the same reference numerals and will not be described again.

[0086] 25, a flow meter 30 and an analyzer 31 are provided in the recirculation pipe 8 downstream of the GRF 9. The flow meter 30 measures the flow rate of the exhaust gas flowing through the recirculation pipe 8 and transmits the measurement value to the control unit. The analyzer 31 measures the combustible components of the exhaust gas flowing through the recirculation pipe 8 and transmits the measurement value to the control unit.

[0087] The control unit calculates the amount of air (amount of oxidizer) required to combustibly treat the combustible components of the exhaust gas based on the measurement values ​​transmitted from the flow meter 30 and the analyzer 31. Based on the calculated required amount of air, the flow rate of air supplied from the oxidizer supply unit 28 is controlled. By controlling the air flow rate in this way, it is possible to supply air at a flow rate appropriate for combusting the exhaust gas.

[0088] Furthermore, as shown in FIG. 26, when oxidant supply units 28-1, 28-2, and 28-3 are provided corresponding to a plurality of re-inlet ports 8b-1, 8b-2, and 8b-3 (see FIG. 24), feedforward control can be performed for each stage by providing a flow meter 30 and an analyzer 31 in each recirculation pipe 8.

[0089] [Eighth embodiment] Next, an eighth embodiment of the present disclosure will be described with reference to FIG. The carbonization furnace 1G of this embodiment differs from the sixth embodiment (FIG. 22) in that a flow meter and an analyzer are provided in the re-discharge pipe 7. The same components as those in the sixth embodiment are designated by the same reference numerals and will not be described again.

[0090] 27, the re-exhaust pipe 7 is provided with a flow meter 32 and an analyzer 33. The flow meter 32 measures the flow rate of the exhaust gas flowing through the recirculation pipe 8 and transmits the measurement value to the control unit. The analyzer 33 measures the combustible components of the exhaust gas flowing through the recirculation pipe 8 and transmits the measurement value to the control unit.

[0091] The control unit calculates the amount of unburned exhaust gas based on the measurement values ​​transmitted from the flow meter 32 and the analyzer 33, and calculates the amount of air (oxidizer amount) required to combust the unburned exhaust gas. The flow rate of air supplied from the oxidizer supply unit 28 is controlled based on the calculated required amount of air. By feedback controlling the air flow rate in this manner, it is possible to supply air at an appropriate flow rate for combusting the exhaust gas.

[0092] Furthermore, as shown in FIG. 28, when oxidant supply units 28-1, 28-2, and 28-3 are provided corresponding to a plurality of re-inlet ports 8b-1, 8b-2, and 8b-3 (see FIG. 24), feedback control can be performed for each stage by providing a flow meter 32 and an analyzer 33 in each recirculation pipe 8.

[0093] [Ninth embodiment] Next, a ninth embodiment of the present disclosure will be described with reference to FIG. The carbonization furnace 1H of this embodiment differs from the first embodiment (FIG. 1) described above in that it is provided with a configuration for preheating the carbonization air. The same components as those in the first embodiment are designated by the same reference numerals and their description will be omitted. This embodiment can be applied to each of the above-described embodiments.

[0094] As shown in Figure 29, a heat exchanger 35 is provided in the re-discharge pipe 7. The heat exchanger 35 exchanges heat between the exhaust gas flowing through the re-discharge pipe 7 and the carbonization air A1. This increases the temperature of the carbonization air, thereby improving the thermal efficiency of the carbonization furnace 1H.

[0095] The carbonization furnace and the control method thereof described in each of the above-described embodiments can be understood, for example, as follows.

[0096] The carbonization furnace (1A) according to the first aspect of the present disclosure comprises a container (5) in which the material to be carbonized (W) is accommodated and carbonized, a recirculation flow path (8) that extracts exhaust gas from the inside of the container through an outlet (8a) and re-introduces the exhaust gas into the container through a re-inlet (8b), and a re-discharge flow path (7) that extracts exhaust gas from the inside of the container through a re-discharge outlet (7a) provided near the re-inlet and discharges it to the outside of the container.

[0097] The recirculation flow path for recirculating the exhaust gas removes flammable exhaust gas generated during carbonization from the inside of the container and reintroduces the exhaust gas into the container through a re-introduction port. The flammable exhaust gas introduced into the container through the re-introduction port diffuses and burns within the container, which is heated to a high temperature, and is incinerated. Because the re-discharge port of the re-discharge flow path is located near the re-introduction port, the burned gas that has been re-introduced and incinerated is preferentially removed from the re-discharge port and discharged to the outside of the container through the re-discharge flow path. In this way, by incinerating the flammable exhaust gas generated inside the container of the carbonization furnace inside the carbonization furnace, environmental standards for exhaust gas released to the outside from the container can be met, and the chemical energy of the exhaust gas can be recovered as thermal energy. This improves the energy efficiency of the carbonization furnace. The exhaust gas recirculated through the recirculation flow path may be all or a portion of the exhaust gas extracted from the outlet. When a portion of the exhaust gas is recirculated, the other portion is sent to a chimney or the like and discharged to the outside of the container.

[0098] The carbonization furnace according to a second aspect of the present disclosure is the carbonization furnace of the first aspect, wherein the re-discharge passage (7) is provided with an exhaust fan (17) that exhausts the exhaust gas to the outside of the container.

[0099] An exhaust fan is installed in the re-exhaust flow path to forcibly exhaust the exhaust gas to the outside of the vessel. This prevents the exhaust gas from flowing back into the vessel by flowing back through the re-exhaust flow path. This is effective, for example, when the chimney height is not large enough and the draft pressure due to the chimney effect is insufficient.

[0100] In the carbonization furnace according to a third aspect of the present disclosure, in the first or second aspect, the re-feeding port (8b) is provided at a position where the material to be carbonized is present.

[0101] The re-injection port is located at the position where the carbonized material is present, so the exhaust gas injected from the re-injection port penetrates between the carbonized material while colliding with the material, thereby promoting the ignition and combustion of the flammable exhaust gas. When the material to be carbonized is undergoing combustion or carbonization reaction, the ignition and combustion of the exhaust gas is further promoted.

[0102] In the carbonization furnace according to the fourth aspect of the present disclosure, in any one of the first to third aspects, the center (7a1) of the re-discharge port (7a) is located at a position that is 10 times or less the hydraulic diameter (D1) of the re-injection port (8b) from the center (8b1) of the re-injection port (8b).

[0103] By locating the center of the re-discharge outlet at a position that is 10 times or less the hydraulic diameter of the re-injection port from the center of the re-injection port and bringing the re-discharge outlet closer to the re-injection port, the post-combustion gas after the exhaust gas introduced from the re-injection port is combusted can be preferentially discharged from the re-discharge port. The distance between the center of the re-discharge port and the center of the re-injection port is preferably 5 times or less, more preferably 3 times or less, and even more preferably 2 times or less, the hydraulic diameter of the re-injection port.

[0104] A carbonization furnace according to a fifth aspect of the present disclosure is provided with one or more combinations in which one re-inlet port (8b) corresponds to one re-discharge port (7a) in any of the first to fourth aspects.

[0105] Since one re-inlet corresponds to one re-discharge port, the distance between the re-inlet and the re-discharge port can be appropriately determined, which allows the post-combustion gas introduced from the re-inlet to be preferentially discharged from the re-discharge port after combustion. The combination of re-inlet and re-ejection ports may be one or more.

[0106] The carbonization furnace according to a sixth aspect of the present disclosure is the carbonization furnace of any one of the first to fourth aspects, wherein a plurality of the re-discharge ports (7a) are provided equidistantly from one of the re-feed ports (8b).

[0107] Since multiple re-exhaust ports are provided at equal distances from one re-inlet, the distance between the re-inlet and each re-exhaust port can be appropriately determined, allowing the post-combustion gas after combustion of the exhaust gas introduced from the re-inlet to be preferentially discharged from each re-exhaust port.

[0108] The carbonization furnace according to the seventh aspect of the present disclosure is, in any one of the first to sixth aspects, such that the inlet (8b) is provided in multiple locations in the stacking direction of the material to be carbonized stacked in the container, and the re-discharge outlet (7a) is provided in multiple locations corresponding to the multiple re-inlet ports (8b).

[0109] The carbonization reaction of the materials stacked in the container progresses in the stacking direction. Therefore, multiple re-feeding ports and re-discharge ports are provided in the stacking direction of the materials to be carbonized, so that the re-feeding ports and re-discharge ports can be used according to the progress of the carbonization reaction.

[0110] The carbonization furnace according to the eighth aspect of the present disclosure, in any one of the first to seventh aspects, is provided with recirculation flow control valves (8-1V, 8-2V, 8-3V) provided in each of the recirculation flow paths (8), re-discharge flow control valves (7-1V, 7-2V, 7-3C) provided in each of the re-discharge flow paths (7), and a control unit that controls the recirculation flow control valves and the re-discharge flow control valves.

[0111] The recirculation flow path and the re-discharge flow path are each provided with a flow control valve, and the timing of flow rate adjustment by the flow control valve can be controlled by the control unit, thereby enabling switching between the recirculation flow path and the re-discharge flow path depending on the progress of the carbonization reaction.

[0112] The carbonization furnace according to the ninth aspect of the present disclosure, in any one of the first to eighth aspects, is provided with temperature sensors (TX1, TX2, TX3) arranged at predetermined positions inside the container so as to correspond to the re-inlet ports (8b) of each of the recirculation flow paths, and the control unit controls the recirculation flow control valves (8-1V, 8-2V, 8-3V) and the re-discharge flow control valves (7-1V, 7-2V, 7-3C) by determining the progress of carbonization of the material to be carbonized based on the measurement values ​​of the temperature sensors.

[0113] By installing temperature sensors at positions corresponding to each re-inlet, the progress of carbonization in the area where the temperature sensors are located can be determined from the measured values ​​of the temperature sensors. By controlling the recirculation flow control valve and the re-exhaust flow control valve based on the progress of carbonization, flammable exhaust gas can be appropriately combusted. For example, the control unit opens the recirculation flow rate adjustment valve and the re-discharge flow rate adjustment valve corresponding to the position where it has determined that carbonization has started, and closes the other recirculation flow rate adjustment valves and re-discharge flow rate adjustment valves. Even if the corresponding recirculation flow rate adjustment valve is closed, the re-discharge flow rate adjustment valve may be controlled to be open while the nearby recirculation flow rate adjustment valve is open.

[0114] A carbonization furnace according to a tenth aspect of the present disclosure is, in any one of the first to ninth aspects, characterized in that the recirculation flow path (8) has an extension portion (8c) arranged so that the re-injection port (8b) is located inside the container.

[0115] By providing the re-injection port inside the container, the exhaust gas can be injected from the re-injection port into a high-temperature region, thereby facilitating ignition and combustion of the re-injected exhaust gas.

[0116] The carbonization furnace according to the eleventh aspect of the present disclosure is the tenth aspect, wherein the length (L5) by which the tip of the extension portion (8c) located inside the container (5) protrudes from the inner surface of the container is equal to or less than the distance (L1) between the center (7a1) of the re-discharge port (7a) and the center (8b1) of the re-injection port (8b).

[0117] By providing a re-injection port inside the container and, in addition, limiting the length that the extension portion protrudes from the inner surface of the container, it is possible to promote ignition and combustion of the re-injected exhaust gas while effectively discharging the post-combustion gas outside the container.

[0118] A carbonization furnace according to a twelfth aspect of the present disclosure is the carbonization furnace of the tenth or eleventh aspect, wherein the extension portion (8c) is formed of a porous member.

[0119] By forming the extension portion from a porous member, exhaust gas can be supplied from inside the container while preventing the carbonized material from entering the recirculation flow path.

[0120] A carbonization furnace according to a thirteenth aspect of the present disclosure is any one of the first to twelfth aspects, and is provided with an oxidant supply section (28) that supplies an oxidant to the area where exhaust gas is introduced from the re-introduction port (8b).

[0121] The oxidizer is injected into the area where the exhaust gas is injected from the re-injection port, which promotes the ignition and combustion of the exhaust gas.

[0122] A carbonization furnace according to a fourteenth aspect of the present disclosure is the thirteenth aspect, wherein a distance (L6) from the inner wall of the container (5) to the center of the oxidant supply section (28) is equal to or less than a distance (L1) between a center (7a1) of the re-discharge port (7a) and a center (8b1) of the re-injection port (8b).

[0123] By limiting the distance from the inner wall of the container to the center of the oxidizer supply section, it is possible to promote ignition and combustion of the re-introduced exhaust gas, while at the same time effectively discharging the post-combustion gas outside the container.

[0124] The carbonization furnace according to a fifteenth aspect of the present disclosure is the one in the thirteenth or fourteenth aspect, and includes regulating valves (28-1, 28-2, 28-3) that regulate the flow rate of the oxidant supplied from the oxidant supply unit (28), and a control unit that controls the regulating valves based on the flow rate and / or components of the exhaust gas introduced from the re-introduction port (8b).

[0125] The flow rate of the oxidizer is adjusted by feedforward control of the adjustment valve based on the flow rate and / or components of the exhaust gas injected from the re-injection port, which allows the supply of an oxidizer at an appropriate flow rate for the combustion of the exhaust gas.

[0126] The carbonization furnace according to a sixteenth aspect of the present disclosure is the one in the thirteenth or fourteenth aspect, and includes regulating valves (28-1, 28-2, 28-3) that regulate the flow rate of the oxidant supplied from the oxidant supply unit (28), and a control unit that controls the regulating valves based on the flow rate and / or components of the exhaust gas discharged from the re-discharge flow path (7).

[0127] The flow rate of the oxidizer is adjusted by feedback controlling the adjustment valve based on the flow rate and / or components of the exhaust gas discharged from the re-discharge flow path, which allows the oxidizer to be supplied at an appropriate flow rate for the combustion of the exhaust gas.

[0128] The carbonization furnace according to the 17th aspect of the present disclosure, in any one of the first to 16th aspects, is provided with a heat exchanger (35) that exchanges heat between the exhaust gas flowing through the re-discharge flow path (7) and the carbonization air supplied to the inside of the container.

[0129] A heat exchanger is installed to heat the carbonization air with exhaust gas, which increases the temperature of the carbonization air and improves the thermal efficiency of the carbonization furnace.

[0130] The carbonization furnace according to an eighteenth aspect of the present disclosure is capable of being attached to a vehicle (3) in any one of the first to seventeenth aspects.

[0131] The control method for a carbonization furnace (1A) according to the first aspect of the present disclosure includes a recirculation process in which exhaust gas is extracted from the inside of a container (5) in which material to be carbonized is stored and carbonized through an extraction outlet (8a) and the exhaust gas is re-introduced into the container through a re-introduction port (8b), and a re-discharge process in which exhaust gas is extracted from the inside of the container through a re-discharge port (7a) provided near the re-introduction port and discharged to the outside of the container. [Explanation of symbols]

[0132] 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H Carbonization furnace 3 vehicles 3a Cargo bed 5 containers 6 Feeding hopper 7 Re-discharge pipe (re-discharge flow path) 7a Re-discharge port 7-1 Lower re-discharge port 7-2 Middle re-discharge port 7-3 Upper re-discharge outlet 7-1V Lower gate valve (flow control valve) 7-2V Middle gate valve (flow control valve) 7-3V Upper gate valve (flow control valve) 8 Recirculation pipe (recirculation flow path) 8a Outlet 8b Reloading port 8b-1 Lower re-entry port 8b-2 Middle re-entry port 8b-3 Upper re-entry port 8-1V Lower gate valve (flow control valve) 8-2V Middle gate valve (flow control valve) 8-3V Upper gate valve (flow control valve) 8c extension 9 GRF 10 Chimney 11 Flow control valve 12 Product charcoal removal section 14 Exhaust pipe 15 IDF 17 Exhaust fan 22 Screw feeder 22a Rotation axis 22b Feather 25 Porous material 27 Carbonization air supply section 28 Oxidant supply section 28-1 Oxidant supply section 28-2 Oxidant supply section 28-3 Oxidant supply section 28-1V Air flow regulator valve 28-2V Air flow regulator 28-3V Air flow regulator 30 Flow meter 31 Analyzer 32 Flow meter 33 Analyzer 35 Heat exchanger A1 Carbonization air D1 Hydraulic diameter (of re-entry inlet) L1 distance W Carbide W1 Product carbon (carbide)

Claims

1. a container in which the material to be carbonized is accommodated and carbonized; a recirculation flow path that extracts exhaust gas from the inside of the container through an outlet and reintroduces the exhaust gas into the inside of the container through a reintroduction port; a re-discharge flow path that extracts exhaust gas from the inside of the container through a re-discharge port provided near the re-introduction port and discharges the exhaust gas to the outside of the container; A carbonization furnace equipped with:

2. The carbonization furnace according to claim 1 , wherein the re-discharge flow path is provided with an exhaust fan for facilitating the exhaust of the exhaust gas to the outside of the container.

3. 2. The carbonization furnace according to claim 1, wherein the re-feeding port is provided at a position where the material to be carbonized is present.

4. 2. The carbonization furnace according to claim 1, wherein the center of the re-discharge port is located at a position 10 times or less hydraulic diameter from the center of the re-injection port.

5. The carbonization furnace according to claim 1 , wherein one or more combinations of one re-inlet and one re-discharge outlet are provided.

6. 2. The carbonization furnace according to claim 1, wherein a plurality of said re-discharge ports are provided equidistantly from one said re-injection port.

7. The re-feeding ports are provided in a plurality in the stacking direction of the materials to be carbonized stacked in the container, The carbonization furnace according to claim 1 , wherein a plurality of the re-discharge ports are provided corresponding to a plurality of the re-feed ports.

8. a recirculation flow rate adjustment valve provided in each of the recirculation flow paths; a re-discharge flow rate adjusting valve provided in each of the re-discharge flow paths; a control unit that controls the recirculation flow rate adjustment valve and the re-discharge flow rate adjustment valve; The carbonization furnace according to claim 1, comprising:

9. a temperature sensor provided at a predetermined position inside the container so as to correspond to the re-inlet of each of the recirculation flow paths; The carbonization furnace according to claim 8, wherein the control unit controls the recirculation flow rate adjustment valve and the re-discharge flow rate adjustment valve by determining the progress of carbonization of the material to be carbonized based on the measurement value of the temperature sensor.

10. 2. The carbonization furnace according to claim 1, wherein the recirculation flow path has an extension portion provided so that the reintroduction port is located inside the container.

11. A carbonization furnace as described in claim 10, wherein the length by which the tip of the extension portion located inside the container protrudes from the inner surface of the container is equal to or less than the distance between the center of the re-discharge port and the center of the re-injection port.

12. The carbonization furnace according to claim 10 , wherein the extension portion is formed of a porous member.

13. The carbonization furnace according to claim 1, further comprising an oxidizer supplying section that supplies an oxidizer to a region where the exhaust gas is introduced from the reintroduction port.

14. The carbonization furnace according to claim 13, wherein the distance from the inner wall of the container to the center of the oxidant supply section is equal to or less than the distance between the center of the re-discharge port and the center of the re-injection port.

15. an adjusting valve for adjusting the flow rate of the oxidant supplied from the oxidant supply unit; a control unit that controls the regulating valve based on the flow rate and / or components of the exhaust gas introduced through the reintroduction port; The carbonization furnace according to claim 13 or 14, comprising:

16. an adjusting valve for adjusting the flow rate of the oxidant supplied from the oxidant supply unit; a control unit that controls the regulating valve based on the flow rate and / or components of the exhaust gas discharged from the re-discharge flow path; The carbonization furnace according to claim 13 or 14, comprising:

17. 2. The carbonization furnace according to claim 1, further comprising a heat exchanger for exchanging heat between the exhaust gas flowing through the re-discharge flow path and the carbonization air supplied to the inside of the container.

18. 2. The carbonization furnace according to claim 1, which is mountable on a vehicle.

19. a recirculation step of extracting exhaust gas from an outlet from the inside of a container in which the material to be carbonized is accommodated and carbonized, and reintroducing the exhaust gas into the container from a re-introduction port; a re-discharge step of removing exhaust gas from the inside of the container through a re-discharge port provided near the re-introduction port and discharging the exhaust gas to the outside of the container; A method for controlling a carbonization furnace having the above structure.

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