Detoxification processing device

Abstract

To more reduce use of combustion aid gas and effectively utilize energy of exhaust gas, in rendering the exhaust gas from an atmosphere furnace harmless.SOLUTION: A detoxification processing device that renders exhaust gas of an atmosphere furnace harmless in the atmosphere furnace that processes a workpiece by filling the furnace with atmosphere gas comprises: a fuel cell that generates power by using fuel gas and oxidant gas; an exhaust gas supply line that supplies the exhaust gas of the atmosphere furnace to the fuel cell as at least a part of fuel gas; and a combustion chamber that burns off-gas discharged from the fuel cell.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This specification discloses a detoxification treatment device. [Background technology]

[0002] Conventionally, as atmospheric furnaces in which atmospheric gas is filled in the furnace to heat-treat workpieces, hydrogen atmosphere furnaces, carburizing furnaces, nitriding furnaces, etc. are known. In such atmospheric furnaces, the amount of atmospheric gas consumed by reaction with the workpieces is small, and most of the atmospheric gas is discharged outside the furnace. The exhaust gas discharged outside the furnace contains hydrogen in a hydrogen atmosphere furnace, carbon monoxide and hydrogen in a carburizing furnace, and hydrogen and ammonia in a nitriding furnace, and it is environmentally undesirable to discharge it directly into the atmosphere. For this reason, the exhaust gas from the atmospheric furnace is usually burned in a combustor to make it harmless, and then discharged into the atmosphere. However, it is difficult to completely burn the exhaust gas from the atmospheric furnace alone, and the exhaust gas is usually burned using a combustion supporting gas such as methane or propane.

[0003] Furthermore, as a technology for effectively utilizing the energy of exhaust gas discharged from an industrial furnace, Patent Document 1 discloses a system that is combined with an industrial heat treatment furnace equipped with a blower that introduces air, and includes a gas turbine generator that expands the exhaust gas from the industrial heat treatment furnace as working gas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-57508 A Summary of the Invention [Problem to be solved by the invention]

[0005] When exhaust gas from an atmospheric furnace is burned using a supporting gas, the carbon dioxide generated by the combustion of methane, propane, or the like used as the supporting gas is also released into the atmosphere, which causes global warming. In addition, although Patent Document 1 discloses a system for converting the energy of exhaust gas from an industrial furnace into electrical energy using a gas turbine generator, this system is a technology that is applied to industrial heat treatment furnaces equipped with a blower that introduces air, and cannot be applied to atmospheric furnaces that do not normally introduce air.

[0006] The main purpose of the detoxification treatment device disclosed herein is to provide a detoxification treatment that can effectively utilize the energy of exhaust gas while further reducing the use of supporting gas when detoxifying exhaust gas from an atmospheric furnace. [Means for solving the problem]

[0007] The detoxification treatment device of the present disclosure employs the following means to achieve the above-mentioned main object.

[0008] The detoxification treatment device of the present disclosure includes: A detoxification treatment device that detoxifies exhaust gas from an atmospheric furnace in which an atmospheric gas is filled in the furnace to treat a workpiece, comprising: a fuel cell that generates electricity using a fuel gas and an oxidant gas; an exhaust gas supply line that supplies exhaust gas from the atmospheric furnace to the fuel cell as at least a part of the fuel gas; a combustor that combusts a fuel off-gas discharged from the fuel cell; The gist of the invention is to provide the following:

[0009] In the detoxification treatment device disclosed herein, exhaust gas from the atmospheric furnace is supplied to the fuel cell as at least a part of the fuel gas, and off-gas discharged from the fuel cell is combusted in a combustor. By using the exhaust gas from the atmospheric furnace as the fuel gas, it is possible to achieve a detoxification treatment that can further reduce the use of supporting gas and effectively utilize the energy of the exhaust gas. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of a detoxification treatment device according to a first embodiment. [Diagram 2] FIG. 13 is a schematic diagram of a detoxification treatment device according to another embodiment. [Diagram 3] FIG. 11 is a schematic configuration diagram of a detoxification treatment device according to a second embodiment. [Figure 4] FIG. 13 is a schematic diagram of a detoxification treatment device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described with reference to the drawings.

[0012] FIG. 1 is a schematic diagram of a detoxification treatment device according to the first embodiment. The detoxification treatment device 10 according to the first embodiment converts the energy of the exhaust gas from a carburizing furnace 1 into electric energy and detoxifies harmful components contained in the exhaust gas. In the carburizing furnace 1, carbon monoxide (CO) generated from a hydrocarbon gas using a converted gas generator 2 is introduced into the furnace as an atmospheric gas, and the workpiece W is heated in the furnace to cause carbon (C) to penetrate and diffuse into the workpiece W. Here, the atmospheric gas is generated by reaction according to the following formula (1), for example, by passing a heated nickel catalyst using propane gas as a raw material. The composition of the exhaust gas discharged from the carburizing furnace 1 includes hydrogen (H2) by-produced during the generation of converted gas, nitrogen (N2) in the air, carbon dioxide (CO2) generated in the carburizing furnace 1, and unreacted carbon monoxide (residual CO) during gas carburization. The detoxification treatment device 10 according to the first embodiment detoxifies the residual CO and H2 contained in the exhaust gas.

[0013] C3H8+3 / 2(O2+6.76N2)→3CO+4H2+5.64N2…(1)

[0014] The detoxification treatment device 10 of the first embodiment comprises a fuel cell module 20, an exhaust gas pipe 31 connecting the exhaust port of the carburizing furnace 1 and the fuel gas pipe 22 of the fuel cell module 20, and a combustor 34 connected to the fuel off-gas pipe 33 of the fuel cell module 20.

[0015] The fuel cell module 20 has a fuel cell stack 21 in which a plurality of unit cells are stacked. In the first embodiment, the fuel cell module 20 is configured as a solid oxide fuel cell (SOFC). Each unit cell includes an electrolyte 21a, an anode 21b (fuel electrode) disposed on one side of the electrolyte 21a, and a cathode 21c (oxidizer electrode) disposed on the other side of the electrolyte 21a. One end of a fuel gas pipe 22 is connected to an inlet of the anode 21b, and a fuel off-gas pipe 33 is connected to the other end of the fuel gas pipe 22. A fuel blower (not shown) is provided in the fuel gas pipe 22. When the fuel blower is operated, the exhaust gas discharged from the carburizing furnace 1 to the exhaust gas pipe 31 is supplied to the anode 21b from the exhaust gas pipe 31 through the fuel gas pipe 22. Furthermore, one end of a fuel off-gas pipe 33 is connected to an outlet of the anode 21b, and a combustor 34 is connected to the other end of the fuel off-gas pipe 33. One end of an air pipe 24 is connected to the inlet of the cathode 21c, and a filter and an air blower (not shown) are provided on the air pipe 24. When the air blower is operated, air is sucked into the air pipe 24 through the filter, and the air is supplied to the cathode 21c through the air pipe 24.

[0016] The combustor 34 introduces the fuel off-gas through the fuel off-gas piping 33 and also introduces a combustion supporting gas such as methane or propane as necessary, and combusts them. The combustion exhaust gas generated by the combustion of the fuel off-gas and the combustion supporting gas in the combustor 34 is discharged into the atmosphere.

[0017] In the detoxification treatment device 10 of the first embodiment thus configured, the exhaust gas discharged from the carburizing furnace 1 to the exhaust gas pipe 31 is supplied to the anode 21b of the fuel cell stack 21 via the fuel gas pipe 22. Meanwhile, air is introduced as an oxidizing gas to the cathode 21c of the fuel cell stack 21 via the air pipe 24. Then, oxide ions (O 2- ) is generated, and the oxide ions permeate the electrolyte 22a and react with hydrogen at the anode 21b to obtain electric energy. The fuel off-gas not used in the electrochemical reaction (power generation) at the anode 21b of each unit cell is a combustible gas containing hydrogen (H2) and carbon monoxide (CO), and is supplied to the combustor 34 via the fuel off-gas piping 33. The fuel off-gas is then burned together with a supporting gas in the combustor 34, rendered harmless, and then discharged into the atmosphere. This makes it possible to convert the energy of the exhaust gas from the carburizing furnace 1 into electric energy and render harmful components contained in the exhaust gas harmless. In addition, since the power generation reaction of a solid oxide fuel cell is an exothermic reaction, the generated heat can also be recovered and reused.

[0018] As described above, the carbon monoxide (residual CO) and hydrogen (H2) contained in the exhaust gas from the carburizing furnace 1 are used as fuel gas for the fuel cell stack 21, so that the amounts of carbon monoxide (CO) and hydrogen (H2) in the exhaust gas can be significantly reduced. Therefore, the amount of supporting gas used in the combustor 34 when burning the exhaust gas in the combustor 34 can be reduced, and the generation of greenhouse gases (carbon dioxide) due to the use of supporting gas can be suppressed.

[0019] In the above-described first embodiment, the detoxification treatment device 10 supplies the exhaust gas discharged from the carburizing furnace 1 directly to the anode 21b of the fuel cell stack 21 through the exhaust gas piping 31. However, since the fuel cell stack 21 is a solid oxide fuel cell stack that operates at high temperatures and the exhaust gas discharged from the carburizing furnace 1 contains hydrogen (H2) and carbon monoxide (CO), carbon may be deposited (caulking) in the anode 21b or in the piping depending on the exhaust gas composition, temperature, pressure, and other conditions. For this reason, water vapor may be added to the exhaust gas to prevent caulking.

[0020] In the first embodiment described above, the fuel cell module 20 is configured as a solid oxide fuel cell (SOFC), but is not limited thereto and may be configured as, for example, a polymer electrolyte fuel cell (PEFC). Fig. 2 is a schematic diagram of a detoxification treatment device 10B of another embodiment. The detoxification treatment device 10B of the other embodiment differs from the detoxification treatment device 10 of the first embodiment in that the fuel cell module 20B is configured as a polymer electrolyte fuel cell (PEFC) and in that the device includes a filter unit 32 that reduces the amount of carbon monoxide (residual CO) contained in the exhaust gas from the carburizing furnace 1 and increases the amount of hydrogen (H2).

[0021] The filter unit 32 is installed in the exhaust gas pipe 31. The filter unit 32 is a shift reactor that generates hydrogen (H2) and carbon dioxide (CO2) by a reaction (carbon monoxide shift reaction) between carbon monoxide (residual CO) contained in the exhaust gas and the water vapor by adding water vapor. The hydrogen (H2) generated in the filter unit 32 is supplied to the anode 21b through the fuel gas pipe 22. In another embodiment, the fuel cell module 20B is configured as a polymer electrolyte fuel cell (PEFC) using a platinum catalyst in the anode 21b, and when carbon monoxide (CO) is supplied to the anode 21b, the performance of the fuel cell stack 21 decreases (voltage decrease) due to CO poisoning of the anode 21b. Therefore, the amount of carbon monoxide (CO) supplied to the anode 21b by the filter unit 32 can be reduced, thereby suppressing the performance decrease of the fuel cell stack 21.

[0022] In the detoxification treatment device 10 of the first embodiment, the fuel cell module 20 is configured as a solid oxide fuel cell (SOFC) in which a metal catalyst such as nickel is used in the anode 21b, and is not easily affected by carbon monoxide, so the filter unit 32 (shift reactor) is omitted, but the filter unit 32 may be provided. The water vapor added to the filter unit 32 can suppress carbon deposition (caulking) in the anode 21b and piping.

[0023] Next, the detoxification treatment device 110 of the second embodiment will be described. FIG. 3 is a schematic diagram of the detoxification treatment device 110 of the second embodiment. The detoxification treatment device 110 of the second embodiment converts the energy of the exhaust gas of the nitriding furnace 101 into electric energy and detoxifies harmful components contained in the exhaust gas. In the nitriding furnace 101, for example, ammonia gas (NH3) as an atmospheric gas is introduced from the ammonia tank 102 into the furnace, the workpiece W is heated in the furnace, and the ammonia that comes into contact with the workpiece W is decomposed into nitrogen (N2) and hydrogen (H2), and the nitrogen is allowed to permeate and diffuse into the inside of the workpiece W. Here, the composition of the exhaust gas discharged from the nitriding furnace 101 includes hydrogen (H2), nitrogen (N2), and ammonia (residual NH3) that is by-produced in the nitriding furnace 101 and unreacted during nitriding. The detoxification treatment device 110 of the second embodiment detoxifies the residual NH3 and hydrogen contained in the exhaust gas.

[0024] In the detoxification treatment device 110 of the second embodiment, the fuel cell module 20 is configured as a solid oxide fuel cell (SOFC), and ammonia (NH3) can also be used as a fuel gas, making it possible to efficiently convert the energy of the exhaust gas into electrical energy. In addition, by consuming the residual NH3 contained in the exhaust gas as fuel gas, the amount of residual NH3 in the exhaust gas can be significantly reduced. Therefore, the amount of supporting gas used in the combustor 34 when combusting the exhaust gas in the combustor 34 can be reduced, and the generation of greenhouse gas (carbon dioxide) due to the use of supporting gas can be suppressed.

[0025] In the second embodiment, the fuel cell module 20 is configured as a solid oxide fuel cell (SOFC), but is not limited thereto, and may be configured as a polymer electrolyte fuel cell (PEFC), for example. In a polymer electrolyte fuel cell (PEFC), performance degradation occurs when ammonia (NH3) is supplied to the anode 21b. For this reason, as shown in the detoxification treatment device 110B according to another embodiment of FIG. 4, when a fuel cell module 20B configured by a polymer electrolyte fuel cell (PEFC) is provided, it is desirable to provide a filter unit 132 in the exhaust gas piping 31 and remove ammonia (NH3) contained in the exhaust gas by the filter unit 132. In the second embodiment, the fuel cell module 20 is configured as a solid oxide fuel cell (SOFC), and the filter unit 132 is omitted, but the filter unit 132 may be provided.

[0026] In addition, in the nitriding furnace 101, in addition to ammonia gas (NH3) as the atmospheric gas, nitrogen gas (N2) may be mixed in order to adjust the nitriding speed. In this case, the hydrogen concentration in the exhaust gas from the nitriding furnace 101 decreases, resulting in a decrease in the hydrogen utilization rate of the fuel cell stack 21. For this reason, the filter unit 132 may be configured as a hydrogen enrichment device that separates nitrogen and hydrogen in the exhaust gas to enrich the exhaust gas in hydrogen.

[0027] In the above-described first and second embodiments and other embodiments, the exhaust gas from the exhaust gas pipe 31 is supplied as the fuel gas to the anode 21b. However, it is also possible to adopt a configuration in which a fuel supply source such as a hydrogen tank is connected to the other end of the fuel gas pipe 22, a mixer is provided in the fuel gas pipe 22, and the other end of the exhaust gas pipe 31 is connected to the mixer, thereby mixing the exhaust gas with the fuel gas from the fuel supply source and supplying the resulting mixture to the anode 21b.

[0028] In the above-described first and second embodiments and other embodiments, the carburizing furnace 1 and the nitriding furnace 101 are used as the atmosphere furnace, but the present invention is not limited to these. For example, the present invention may be applied to any atmosphere furnace, such as a hydrogen atmosphere furnace, as long as it uses an atmosphere gas that can also be used as a fuel gas for a fuel cell.

[0029] The above describes the form for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms without departing from the gist of the present disclosure. [Industrial Applicability]

[0030] The present disclosure can be used in the manufacturing industry of detoxification treatment devices, etc. [Explanation of symbols]

[0031] 1 carburizing furnace (atmosphere furnace), 10, 10B, 110, 110B harmless treatment device, 21 fuel cell stack (fuel cell), 31 exhaust gas piping (exhaust gas supply line), 32, 132 filter section, 34 combustor, 101 nitriding furnace (atmosphere furnace).

Claims

1. A detoxification treatment device that detoxifies exhaust gas from an atmospheric furnace in which an atmospheric gas is filled in the furnace to treat a workpiece, comprising: a fuel cell that generates electricity using a fuel gas and an oxidant gas; an exhaust gas supply line that supplies exhaust gas from the atmospheric furnace to the fuel cell as at least a part of the fuel gas; a combustor that combusts a fuel off-gas discharged from the fuel cell; A detoxification treatment device comprising:

2. The detoxification treatment device according to claim 1, A filter unit is provided in the exhaust gas supply line and reduces some of the components of the exhaust gas. Detoxification treatment device.

3. The detoxification treatment device according to claim 2, The atmospheric furnace is a carburizing furnace, The filter unit reduces carbon monoxide contained in the exhaust gas from the carburizing furnace. Detoxification treatment device.

4. The detoxification treatment device according to claim 2, The atmospheric furnace is a nitriding furnace, The filter unit reduces ammonia contained in the exhaust gas from the nitriding furnace. Detoxification treatment device.

5. The detoxification treatment device according to claim 1, The atmospheric furnace is a carburizing furnace, The detoxification treatment device adds water vapor to the exhaust gas from the carburizing furnace so as to suppress carbon deposition in a high-temperature environment. Detoxification treatment device.

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