Thermoelectric power generation device and thermoelectric power generation method

Abstract

To stably prevent the occurrence of electric leakage over a long period of time when thermoelectric power generation is performed in a manufacturing facility line of a steel mill.SOLUTION: A thermoelectric power generation unit used by being attached to a manufacturing facility line of a steel mill, comprises: a heat-receiving plate; a cooling plate opposing the heat-receiving plate; a thermoelectric power generation module arranged between the heat-receiving plate and the cooling plate; and a sealing member annularly arranged between the heat-receiving plate and the cooling plate so as to surround the thermoelectric power generation module, wherein the heat-receiving plate comprises temperature lowering means for relatively lowering a temperature at an outer peripheral part of the heat-receiving plate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermoelectric power generation device that is attached to a line of manufacturing equipment in a steelworks and used, and a thermoelectric power generation method that uses the thermoelectric power generation device. [Background technology]

[0002] It has long been known that when a temperature difference is applied to dissimilar conductors or semiconductors, an electromotive force is generated between the high-temperature and low-temperature parts. This phenomenon is known as the Seebeck effect, and thermoelectric power generation devices that use thermoelectric elements to directly convert heat into electricity have been put into practical use.

[0003] By using a thermoelectric generator, thermal energy that has not been utilized in the past can be effectively utilized as electric power, and therefore the use of thermoelectric generators is being promoted in various fields.

[0004] For example, the present inventors have proposed using thermoelectric power generation devices in the manufacturing equipment rows of steelworks (Patent Documents 1 to 3). Since various processes that are carried out at high temperatures, such as ironmaking, steelmaking, casting, hot rolling, and heat treatment, can be carried out in steelworks, converting the excess heat generated in these processes into electricity would contribute to energy conservation and a reduction in CO2 emissions. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-203301 [Patent Document 2] Japanese Patent Application Publication No. 2018-058082 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-119308 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when thermoelectric power generation is actually attempted in a steelworks manufacturing equipment row, it has been found that there is a problem in that electrical leakage is likely to occur.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to prevent the occurrence of leakage current when thermoelectric power generation is performed in a row of manufacturing equipment in a steelworks. [Means for solving the problem]

[0008] As a result of intensive research to achieve the above object, the inventors have discovered that the cause of the leakage current is the intrusion of moisture and iron powder (including iron oxide powder) into the thermoelectric power generation device, particularly the thermoelectric power generation module.

[0009] In steelworks, not only are various processes carried out at high temperatures, but cooling water is also used to cool the workpieces and manufacturing equipment. For example, in the continuous casting process, cooling water is used to cool the rollers that come into contact with the hot steel slab. In this case, thermoelectric generators installed in the manufacturing equipment rows are exposed to water vapor in addition to high temperatures. As a result, it has been found that moisture can enter the thermoelectric generators, causing short circuits.

[0010] In addition, dust resulting from the manufacturing process is inevitably present around the rows of manufacturing equipment in steelworks. The main component of the dust is iron powder derived from the steel being processed. It was discovered that the iron powder is so fine that it penetrates into the thermoelectric generator and causes a short circuit. Most of the iron powder has been oxidized to form iron oxide. Although iron oxide conducts less electricity than metallic iron, it is not a perfect insulator; for example, wustite has a resistance of 30 Ω. -1 cm -1 250 Ω for magnetite -1 cm -1Iron powder has electrical conductivity of about 1000 kJ / cm. Therefore, if iron powder gets inside a thermoelectric generator, it can cause a current leak. Furthermore, if fine iron powder (iron oxide powder) gets inside a thermoelectric generator, moisture tends to aggregate and be retained around the iron powder, which is thought to synergistically increase the risk of a current leak.

[0011] As such, it was found that the area around the rows of manufacturing equipment in a steelworks is an extremely harsh environment with moisture and fine iron powder present, making it extremely susceptible to electrical leakage.

[0012] The present invention was completed based on the above findings, and the gist of the present invention is as follows.

[0013] 1. A thermoelectric power generation device that is attached to a train of manufacturing equipment in a steelworks, A heat receiving plate; a cooling plate facing the heat receiving plate; a thermoelectric power generation module disposed between the heat receiving plate and the cooling plate; a sealing member annularly disposed between the heat receiving plate and the cooling plate so as to surround the thermoelectric power generation module, The thermoelectric power generation device, wherein the heat receiving plate is provided with a cooling means for relatively lowering the temperature at the outer periphery of the heat receiving plate.

[0014] 2. The thermoelectric power generating device according to item 1 above, wherein the temperature reducing means is configured to relatively lower the emissivity of the outer periphery of the heat receiving plate.

[0015] 3. The thermoelectric power generation device described in 2 above, wherein the temperature reduction means is configured to provide black Ni plating on parts other than the outer periphery of the heat receiving plate, and not provide black Ni plating on the outer periphery, thereby relatively lowering the emissivity of the outer periphery.

[0016] 4. The thermoelectric power generation device according to item 2 above, wherein the temperature reducing means is configured to relatively reduce the emissivity of the outer periphery by relatively reducing the surface roughness of the outer periphery.

[0017] 5. A thermoelectric power generation device described in any one of claims 2 to 4 above, wherein the temperature reduction means is configured to lower the emissivity of the portion of the heat receiving plate where the thermoelectric power generation module is not provided than the portion where the thermoelectric power generation module is provided.

[0018] 6. Installing the thermoelectric power generation device described in 1 or 2 above in a line of manufacturing equipment at a steelworks; A thermoelectric power generation method for converting heat into electric power by the thermoelectric power generation device. [Effects of the Invention]

[0019] According to the present invention, when a thermoelectric power generating device is used in a production line of steelworks, it is possible to prevent leakage of electricity caused by the intrusion of moisture or fine iron powder. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view schematically illustrating a structure of a thermoelectric power generation device according to a first embodiment. [Figure 2] 1 is a schematic diagram showing the overall structure of a thermoelectric power generation device according to a first embodiment. [Figure 3] FIG. 4 is a cross-sectional view schematically illustrating the structure of a thermoelectric power generation device according to a second embodiment. [Figure 4] FIG. 10 is a cross-sectional view schematically illustrating the structure of a thermoelectric power generation device according to a third embodiment. [Figure 5] FIG. 10 is a cross-sectional view schematically illustrating the structure of a thermoelectric power generation device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Next, a method for carrying out the present invention will be specifically described. Note that the following description shows an example of a preferred embodiment of the present invention, and the present invention is not limited to the following description in any way.

[0022] [Thermoelectric power generation device] A thermoelectric power generation device in one embodiment of the present invention is a thermoelectric power generation device that is attached to a row of manufacturing equipment in a steelworks and used, and includes a heat receiving plate, a cooling plate facing the heat receiving plate, a thermoelectric power generation module arranged between the heat receiving plate and the cooling plate, and a sealing member.

[0023] (heat receiving plate) The thermoelectric power generation device of the present invention includes a heat receiving plate for receiving heat from a heat source. When using the thermoelectric power generation device of the present invention, the thermoelectric power generation device is simply installed so that the heat receiving plate is located on the heat source side. After the heat from the heat source is received by the heat receiving plate, it is transferred to one side (high temperature side) of the thermoelectric power generation module.

[0024] The material of the heat receiving plate is not particularly limited, but from the viewpoint of heat resistance, it is preferable to use at least one selected from the group consisting of metal, ceramic, and carbon. The metal is not particularly limited, but it is preferable to use at least one selected from the group consisting of copper, copper alloy, aluminum, aluminum alloy, and steel.

[0025] The heat receiving plate is provided with a cooling means for relatively lowering the temperature at the outer periphery of the heat receiving plate, as will be described later.

[0026] (Cooling plate) The thermoelectric power generation device of the present invention includes a cooling plate facing the heat receiving plate. When using the thermoelectric power generation device of the present invention, the thermoelectric power generation device is simply installed so that the cooling plate is located on the side opposite the heat source. The other surface (low temperature side) of the thermoelectric power generation module is cooled by the cooling plate.

[0027] Any cooling plate can be used as long as it can cool the thermoelectric power generation module. The cooling plate may be, for example, a heat sink or a heat exchanger, but is preferably a heat exchanger from the viewpoint of cooling efficiency. The heat exchanger may be, for example, a water-cooled plate having a cooling water flow path therein. If the cooling plate is a heat sink, it is preferably provided with heat dissipation fins to improve cooling efficiency.

[0028] The material of the cooling plate is not particularly limited, but from the viewpoint of thermal conductivity, it is preferably made of a metal. The metal is not particularly limited, but it is preferable to use at least one selected from the group consisting of copper, copper alloy, aluminum, and aluminum alloy, and among them, aluminum or an aluminum alloy is preferable.

[0029] (Thermoelectric power generation module) The thermoelectric power generation device of the present invention includes a thermoelectric power generation module disposed between the heat receiving plate and the cooling plate, i.e., the heat receiving plate is disposed on the high temperature side of the thermoelectric power generation module, and the cooling plate is disposed on the low temperature side.

[0030] The number of thermoelectric power generation modules per thermoelectric power generation device is not particularly limited, and may be one or more. In other words, one or more thermoelectric power generation modules may be provided between a pair of heat receiving plate and cooling plate. In this case, the thermoelectric power generation modules may be fixed together by a fixing member.

[0031] The thermoelectric power generation module is not particularly limited and any thermoelectric power generation module can be used. An example of the structure of a thermoelectric power generation module that can be suitably used in the present invention will be described below.

[0032] In one embodiment of the present invention, a thermoelectric power generation module including a pair of opposing insulating substrates and a plurality of thermoelectric power generation elements sandwiched between the pair of insulating substrates can be used.

[0033] (insulating substrate) To ensure insulation between the thermoelectric power generation element and the heat receiving plate and cooling plate, the thermoelectric power generation module preferably includes a pair of insulating substrates. The thermoelectric power generation element is sandwiched between the pair of insulating substrates. The insulating substrates also function to absorb differences in thermal expansion in the planar direction between the components (thermoelectric power generation element, heat receiving plate, cooling plate, etc.) in contact with the insulating substrates.

[0034] The insulating substrate may be any substrate having insulating properties. The insulating substrate may be a rigid substrate or a flexible substrate, but is preferably a sheet-like flexible substrate because a thinner substrate is better from the viewpoint of thermal conductivity.

[0035] The insulating substrate may be made of any insulating material, such as ceramic or resin, but is preferably made of resin. Any resin can be used, but from the viewpoint of heat resistance, polyethylene terephthalate (PET) or polyimide is preferred, and polyimide is more preferred.

[0036] (Thermoelectric power generation element) A thermoelectric power generation element, also known as a thermoelectric conversion element, has the function of converting heat into electricity. Specifically, an electromotive force is generated by creating a temperature difference between one side of the thermoelectric power generation element and the other side.

[0037] The thermoelectric power generating element is not particularly limited, and any element capable of generating thermoelectric power can be used. A typical thermoelectric power generating element has a structure in which a pair of p-type and n-type semiconductors are combined. The thermoelectric power generating element can be made of at least one material selected from the group consisting of BiTe, PbTe, Si-Ge, silicide, skutterudite, transition metal oxide, zinc antimony, boron compound, clathrate compound, cluster solid, zinc oxide, and carbon nanotube.

[0038] Generally, multiple thermoelectric generation elements are used in a thermoelectric generation module because the electromotive force per thermoelectric generation element is small. There is no particular limit to the number of thermoelectric generation elements used, and it can be determined according to the required power. If the number of thermoelectric generation elements per thermoelectric generation module is too small, a large number of thermoelectric generation modules will be required to ensure the required amount of power generation. Therefore, it is preferable that the number of thermoelectric generation elements per thermoelectric generation module be 2,000 or more. On the other hand, because there is a risk that the thermoelectric generation module will cease to function if even a portion of the elements contained in the thermoelectric generation module is damaged, it is desirable that the number of thermoelectric generation elements per thermoelectric generation module is not excessively large; specifically, it is preferable that the number be 6,000 or less.

[0039] Furthermore, if the ratio of the area occupied by the thermoelectric element to the area of ​​the thermoelectric power generation module is small, the power generation efficiency will be low. In addition, the heat transfer from the high temperature side to the low temperature side via the thermoelectric element will be reduced, Therefore, the temperature rise on the high-temperature side becomes significant. As a result, the temperature on the high-temperature side exceeds the heat resistance temperature of the thermoelectric element, which may damage the thermoelectric element. Therefore, the ratio of the area occupied by the thermoelectric element to the area of ​​the thermoelectric power generation module is preferably 0.2 or more, and more preferably 0.3 or more.

[0040] (Outer sealing frame) It is preferable to provide an outer sealing frame between the pair of insulating substrates to seal the outer peripheries of the pair of insulating substrates. By sealing the outer peripheries of the insulating substrates in this manner, it is possible to more reliably prevent moisture and iron powder from entering the interior of the thermoelectric power generation module from the outer periphery. The outer sealing frame may be provided near the outer edge of the insulating substrates so as to surround all of the thermoelectric power generation elements provided in the thermoelectric power generation module.

[0041] The shape of the peripheral sealing frame is not particularly limited as long as it is frame-shaped. However, when the insulating substrate is rectangular, it is preferable that the peripheral sealing frame also be rectangular in shape from the viewpoint of widening the space for mounting the thermoelectric power generation element. Note that the shape of the peripheral sealing frame here refers to the shape of the peripheral sealing frame when viewing the thermoelectric power generation module from a direction perpendicular to the insulating substrate.

[0042] The cross-sectional shape of the peripheral sealing frame is not particularly limited and may be any shape. For example, the cross-sectional shape may be rectangular or circular. For example, an O-ring may be used as a peripheral sealing frame having a circular cross-sectional shape.

[0043] The material of the peripheral sealing frame is not particularly limited, and various materials such as resin, ceramic, and metal can be used. When using resin, it is sufficient to use a resin having heat resistance appropriate for the usage environment. Furthermore, it is preferable to use at least one metal selected from the group consisting of copper, copper alloy, aluminum, aluminum alloy, and steel.

[0044] (Sealing member) The thermoelectric power generation device of the present invention includes a sealing member that is annularly disposed between the heat receiving plate and the cooling plate so as to surround the thermoelectric power generation module.

[0045] Without the sealing member, moisture and iron powder would enter the thermoelectric generator through the gap between the heat receiving plate and the cooling plate, making it more likely to cause leakage current. Therefore, in the present invention, an annular sealing member is provided between the heat receiving plate and the cooling plate so as to surround the thermoelectric generation module, thereby preventing moisture and iron powder from entering through the gap between the heat receiving plate and the cooling plate.

[0046] From the viewpoint of sealing performance, it is preferable that the sealing member be in direct contact with the heat receiving plate and the cooling plate.

[0047] The sealing member is preferably, for example, an annular elastic sealing member. The annular elastic sealing member may have any shape, such as a rectangular or circular cross section, but is preferably an O-ring.

[0048] The material of the sealing member is not particularly limited, and any material can be used as long as it can seal the gap and prevent the intrusion of moisture and iron powder. The material of the sealing member is preferably an elastic material, and more preferably an insulating elastic material. Typically, rubber can be used as the insulating elastic material. Note that the rubber also includes elastomers. In particular, from the viewpoint of heat resistance, it is preferable to use fluororubber, and in particular, it is preferable to use perfluoroelastomer.

[0049] In addition, when an outer peripheral sealing frame is provided in the thermoelectric power generation module as described above, the synergistic effect of the sealing member and the outer peripheral sealing frame can more effectively prevent moisture and iron powder from entering the thermoelectric power generation module.

[0050] (thermal conductive sheet) A thermally conductive sheet is preferably provided between the heat receiving plate and the thermoelectric power generation module. Also, a thermally conductive sheet is preferably provided between the cooling plate and the thermoelectric power generation module. By providing a thermally conductive sheet, the thermal contact resistance between the components can be reduced and thermoelectric power generation efficiency can be improved. The thermally conductive sheet may be provided only between the heat receiving plate and the thermoelectric power generation module or between the cooling plate and the thermoelectric power generation module, but it is preferable to provide it on both sides. The thermally conductive sheet also has the function of absorbing the difference in thermal expansion in the thickness direction between the components (thermoelectric power generation module, heat receiving plate, cooling plate, etc.) that are in contact with the thermally conductive sheet.

[0051] The thermally conductive sheet is not particularly limited as long as it can be used in the environment in which the thermoelectric power generation module is used, but from the viewpoint of thermal conductivity, it is preferable to use a graphite sheet.

[0052] (fastening means) The thermoelectric generator of the present invention preferably further comprises a fastening means for fastening the heat receiving plate and the cooling plate together. By fastening the heat receiving plate and the cooling plate together with the fastening means, the adhesion between the components is increased, and as a result, the sealing performance of the sealing member and the peripheral sealing frame described above can be further improved. Note that, here, "fastening the heat receiving plate and the cooling plate" means applying a force in a direction that brings the heat receiving plate and the cooling plate closer to each other to fix them.

[0053] The fastening means may be any means capable of fastening the heat receiving plate and the cooling plate, but typically the fastening means comprises a bolt inserted through the heat receiving plate and the cooling plate. The fastening means preferably also comprises a biasing member that biases the heat receiving plate and the cooling plate in a direction that brings them closer together. A coil spring is preferably used as the biasing member.

[0054] The position where the fastening means is provided is not particularly limited, and the fastening means can be provided at any position. From the viewpoint of avoiding interference with the thermoelectric power generation module, it is preferable to provide the fastening means at a position where no thermoelectric power generation module is present, i.e., outside the thermoelectric power generation module. However, the fastening means can also be provided so as to penetrate the thermoelectric power generation module. In one embodiment of the present invention, the thermoelectric power generation device can include both fastening means (first fastening means) provided outside the thermoelectric power generation module and fastening means (second fastening means) provided so as to penetrate the thermoelectric power generation module.

[0055] When the thermoelectric generator includes a fastening means, the sealing member is preferably arranged in an annular shape outside the fastening means.

[0056] (support member) Furthermore, it is preferable to provide a support member between the heat receiving plate and the cooling plate to support the sealing member. The installation position of the support member is not particularly limited, but it can typically be installed between the insulating substrate on the heat receiving plate side and the heat receiving plate.

[0057] The material of the support member is not particularly limited, but is preferably made of ceramic from the viewpoints of electrical insulation, heat insulation, heat resistance, strength, and the like.

[0058] [Thermoelectric power generation method] In one embodiment of the present invention, a thermoelectric power generation method includes installing the above-described thermoelectric power generation device in a row of manufacturing equipment at a steelworks, and converting heat into electric power using the thermoelectric power generation device. As described above, the surroundings of the rows of manufacturing equipment at a steelworks are an extremely harsh environment, with moisture and fine iron powder present, making electrical leakage highly likely to occur. However, by using a thermoelectric power generation device having the above-described structure, it is possible to prevent moisture and iron powder from entering the thermoelectric power generation device, particularly the thermoelectric power generation module. As a result, electrical leakage is prevented, enabling stable thermoelectric power generation.

[0059] The production line of the steelworks is not particularly limited, and any production line having a heat source can be used. Examples of production line that can be particularly suitably applied include a continuous casting line and a hot rolling line.

[0060] (lower temperature means) As described above, the thermoelectric generator of the present invention includes a sealing member disposed in an annular shape between the heat receiving plate and the cooling plate so as to surround the thermoelectric power generation module. The provision of the sealing member makes it possible to prevent moisture and iron powder from entering through the gap between the heat receiving plate and the cooling plate.

[0061] However, when a thermoelectric power generation device equipped with a sealing member was installed and used in an actual steelworks production line, a problem occurred: although electrical leakage was prevented immediately after the start of use, electrical leakage became more likely as the period of use increased. The inventors investigated the cause and found that, when used for a long period of time in a high-temperature environment, the sealing member deteriorates due to heat, reducing its sealing function, and the thermoelectric power generation module is no longer able to adequately prevent moisture and iron powder from entering the interior. In other words, steelworks have many high-temperature heat sources, such as molten steel and steel slabs in continuous casting processes, compared to general factories and plants. Therefore, when thermoelectric power generation is performed in steelworks, the sealing member deteriorates rapidly.

[0062] Therefore, in the present invention, by using a heat receiving plate equipped with a cooling means for relatively lowering the temperature at the outer periphery, it is possible to prevent deterioration of the sealing member due to heat. That is, since the sealing member is installed so as to surround the thermoelectric power generation module, it comes into contact with the outer periphery of the heat receiving plate. Therefore, by relatively lowering the temperature at the outer periphery of the heat receiving plate using the cooling means, the heat transferred to the sealing member is reduced, and deterioration is suppressed.

[0063] In this way, by using a heat receiving plate equipped with a low-temperature means in combination with a sealing member, it is possible to stably prevent the occurrence of electrical leakage over a long period of time when performing thermoelectric power generation in a steelworks manufacturing equipment row.

[0064] The cooling means may be any means capable of relatively lowering the temperature at the outer periphery of the heat receiving plate. The cooling means may be a means for lowering the temperature at the outer periphery, or a means for relatively lowering the temperature at the outer periphery by increasing the temperature at a region other than the outer periphery (hereinafter referred to as the center for convenience).

[0065] In one embodiment of the present invention, the cooling means may be configured to relatively lower the emissivity of the outer periphery of the heat receiving plate. In this case, the cooling means may be a means for lowering the emissivity of the outer periphery, or a means for relatively lowering the emissivity of the outer periphery by increasing the emissivity of a region other than the outer periphery (central portion).

[0066] By making the emissivity of the outer periphery of the heat receiving plate relatively low, it is possible to suppress the temperature rise of the outer periphery due to radiant heat from the heat source, and as a result, it is possible to suppress the deterioration of the sealing member. .

[0067] If the emissivity of the central portion is increased to relatively decrease the emissivity of the peripheral portion, the heat receiving efficiency of the peripheral portion will be the same as if no cooling means were present. However, because the heat receiving efficiency of the central portion is high, the amount of power generation can be maintained even if the distance from the heat source is increased. Therefore, by increasing the distance from the heat source, the temperature of the peripheral portion can be reduced without reducing the amount of power generation.

[0068] For example, the temperature reducing means is preferably configured to provide black Ni plating on a portion of the heat receiving plate other than the outer periphery, and not to provide black Ni plating on the outer periphery, thereby relatively lowering the emissivity of the outer periphery. In other words, the thermoelectric generator of the present invention preferably includes a heat receiving plate on which black Ni plating is selectively formed on a portion other than the outer periphery.

[0069] In addition to black Ni plating, other methods for increasing emissivity include black painting and black anodizing. However, black Ni plating is extremely suitable because it has superior heat resistance and durability compared to other methods and can be applied regardless of the type of substrate.

[0070] The black Ni plating may be applied at least to the heat source side (opposite the cooling plate) of the heat receiving plate. The side surfaces and the cooling plate side of the heat receiving plate do not necessarily need to be black Ni plated, but they may be. If the side surfaces and the cooling plate side are not black Ni plated, masking of these surfaces is required before plating, and the masking must be removed after plating. However, if black Ni plating is applied to these surfaces, the masking step is not required, making manufacturing easier.

[0071] The method for providing black Ni plating on the portions other than the outer periphery of the heat receiving plate is not particularly limited, and any method can be used. For example, plating may be performed while the outer periphery of the heat receiving plate is masked, and a black Ni plating film may be selectively formed in the center of the heat receiving plate. Alternatively, after black Ni plating is applied to the entire surface of the heat receiving plate, the black Ni plating film on the outer periphery may be removed by a method such as grinding to expose the metal surface of the heat receiving plate, which is the base material.

[0072] The black Ni plating can be formed by any plating method, regardless of whether it is electrolytic plating or electroless plating. When electrolytic plating is used, the black Ni plating film may typically be a Ni-Zn alloy plating. When electroless plating is used, the black Ni plating film may be a Ni-P plating film. After forming a Ni plating film by plating, a blackening treatment can also be performed to form a black Ni plating film. The method of the blackening treatment is not particularly limited, but an oxidation treatment using an acid or the like can be used.

[0073] The thickness of the black Ni plating film is not particularly limited, but is preferably 10 to 20 μm, and more preferably 15±1.5 μm (that is, 13.5 to 16.5 μm).

[0074] In another embodiment, the temperature reducing means may be configured to relatively reduce the emissivity of the outer periphery by relatively reducing the surface roughness of the outer periphery. The method for controlling the surface roughness is not particularly limited, and any method such as shot blasting, polishing, grinding, etc. may be used alone or in combination. For example, to relatively reduce the surface roughness of the outer periphery, the outer periphery may be polished, or conversely, the central portion may be roughened, or both may be performed. Furthermore, if the original surface roughness of the material used to manufacture the heat receiving plate is high, the surface roughness of the outer periphery may be reduced by a process such as blasting. For example, shot blasting may be performed on the outer periphery and the central portion under different conditions to reduce the surface roughness of the outer periphery. The thickness of the upper portion may be smaller than that of the central portion.

[0075] In this embodiment, it is important that the surface roughness of the outer periphery of the heat receiving plate is relatively smaller than the surface roughness of the portion other than the outer periphery (the central portion). Therefore, the surface roughness of each of the outer periphery and the central portion is not particularly limited. For example, if the arithmetic mean roughness Ra of the central portion is 5.0 μm or more, the arithmetic mean roughness Ra of the outer periphery may be less than 5.0 μm. The lower limit of the arithmetic mean roughness Ra of the outer periphery is not particularly limited, but may be, for example, 0.1 μm or more. On the other hand, the upper limit of the arithmetic mean roughness Ra of the central portion is also not particularly limited, but may be, for example, 15 μm or less.

[0076] As an example, two copper heat receiving plates were prepared. One was shot-blasted to an arithmetic mean roughness Ra of 10 μm, and the other was shot-blasted to an arithmetic mean roughness Ra of 1 μm. These heat receiving plates were radiantly heated using the same heat source, and the heat input to each was measured. When measuring the heat input, the surface temperature of the heat receiving plate on the heat source side was measured with a non-contact thermometer, and the temperatures of other parts were measured with thermocouples. As a result, the heat input to the heat receiving plate with an arithmetic mean roughness Ra of 1 μm was approximately 81% of the heat input to the heat receiving plate with an arithmetic mean roughness Ra of 10 μm. This result also demonstrates that emissivity (i.e., thermal absorptivity) can be effectively controlled by adjusting the surface roughness.

[0077] As described above, deterioration of the sealing member can be suppressed by using a temperature-reducing means to reduce the emissivity of the outer periphery of the heat receiving plate. However, if the emissivity is reduced to the portion where the thermoelectric power generation module is installed, the power generation efficiency will decrease. Therefore, it is preferable that the temperature-reducing means is configured to lower the emissivity of the portion of the heat receiving plate where the thermoelectric power generation module is not installed compared to the portion where the thermoelectric power generation module is installed.

[0078] The area of ​​the region where the temperature is relatively lowered by the low-temperature means (hereinafter referred to as the "low-temperature region") is not particularly limited. However, if the area of ​​the low-temperature region is too large, the thermal energy that can be received by the heat receiving plate will decrease, resulting in a significant decrease in power generation efficiency. Therefore, it is preferable that the ratio of the area of ​​the low-temperature region to the area of ​​the heat receiving plate be 40% or less. On the other hand, if the ratio of the area of ​​the low-temperature region to the area of ​​the heat receiving plate is too small, the effect of suppressing deterioration of the sealing member will be reduced. Therefore, from the perspective of further enhancing the effect of suppressing deterioration of the sealing member, it is preferable that the ratio of the area of ​​the low-temperature region to the area of ​​the heat receiving plate be 26% or more, and preferably 36% or more.

[0079] Next, the structure of the thermoelectric power generation device of the present invention will be described in more detail with reference to the drawings. Note that the embodiments described below are all examples of preferred embodiments of the present invention, and the present invention is not limited to these embodiments.

[0080] (First embodiment) 1 is a cross-sectional view showing the structure of a thermoelectric power generation device 1 according to a first embodiment of the present invention. The thermoelectric power generation device 1 includes a heat receiving plate 10 and a cooling plate 20 arranged opposite each other, and a thermoelectric power generation module 30 sandwiched between them.

[0081] The thermoelectric power generation module 30 includes a pair of opposing insulating substrates 31 and a plurality of thermoelectric power generation elements 32 sandwiched between the insulating substrates 31. The plurality of thermoelectric power generation elements 32 are connected to each other by electrodes 33.

[0082] A heat-conducting sheet 40 is provided between the heat-receiving plate 10 and the thermoelectric power generation module 30, and similarly, a heat-conducting sheet 40 is provided between the cooling plate 20 and the thermoelectric power generation module 30. By using the heat-conducting sheet 40 in this way, heat can be easily transferred, thereby This can improve power generation efficiency.

[0083] Furthermore, an annular sealing member 50 is disposed between the heat reception plate 10 and the cooling plate 20. In this embodiment, the sealing member 50 is in direct contact with the upper surface of the heat reception plate 10 and the lower surface of the cooling plate 20, and is provided on the outer edge of the thermoelectric power generation device 1 so as to surround the thermoelectric power generation module 30. By providing the sealing member 50 in this manner, it is possible to prevent moisture and iron powder from entering from the outside.

[0084] The sealing member 50 in this embodiment is an elastic seal member (packing) having a substantially rectangular cross section as shown in Fig. 1, but as mentioned above, it is also preferable to use an O-ring as the sealing member 50. A groove for installing the sealing member 50 may be provided on one or both of the upper surface of the heat receiving plate 10 and the lower surface of the cooling plate 20. The depth of the groove is less than the height of the sealing member 50 (or the diameter in the case of an O-ring).

[0085] FIG. 2 is a schematic diagram showing the entire thermoelectric generator 1 shown in FIG. 1, with the upper part showing the cross-sectional structure and the lower part showing the structure of the lower surface (heat source side surface) of the heat receiving plate 10.

[0086] A cooling means is provided on the underside of the heat receiving plate 10 to relatively lower the temperature of the outer periphery of the heat receiving plate 10. In this example, the central portion 11, which is the area other than the outer periphery of the heat receiving plate, is plated with black Ni, while the outer periphery 12 is not plated with black Ni, leaving the metal base material constituting the heat receiving plate 10 exposed. The sealing member 50 is installed at a position corresponding to the outer periphery 12 of the heat receiving plate 10, and the cooling means prevents deterioration. Meanwhile, the area of ​​the central portion 11 where the black Ni plating is provided is equal to or larger than the area of ​​the thermoelectric power generation module 30. Therefore, the amount of heat transferred from the central portion 11 to the thermoelectric power generation module 30 is not reduced, and therefore power generation efficiency is maintained.

[0087] In this example, the central portion 11 of the heat receiving plate 10 is plated with black Ni, but any other means can be used as the temperature reducing means. For example, as mentioned above, the surface roughness of the peripheral portion 12 may be made lower than that of the central portion 11, thereby reducing the temperature of the peripheral portion 12 relatively.

[0088] 2, the shape of the heat receiving plate 10 is square, but the shape of the heat receiving plate 10 is not particularly limited and may be any shape. However, from the viewpoints of ease of manufacture, ease of installation, and effective use of area, it is preferable that the shape of the heat receiving plate is rectangular.

[0089] 2, the central portion 11 and the peripheral portion 12 are arranged symmetrically with respect to the center of the heat receiving plate 10. In other words, the width of the peripheral portion 12 on each side of the heat receiving plate 10 is equal. However, the dimensions of the peripheral portion 12 can be selected arbitrarily depending on the arrangement of the thermoelectric power generation modules 30. For example, if the thermoelectric power generation modules 30 are arranged asymmetrically with respect to the heat receiving plate 10, the central portion 11 and the peripheral portion 12 can also be arranged asymmetrically accordingly.

[0090] The area of ​​the outer periphery is not particularly limited and may be determined taking into consideration the structure and power generation efficiency of the thermoelectric generator. However, from the viewpoint of further enhancing the effect of preventing thermal degradation of the sealing member, the area of ​​the outer periphery is preferably 20% or more of the area of ​​the heat receiving plate, more preferably 26% or more, and even more preferably 36% or more. On the other hand, if the area of ​​the outer periphery is too large, the heat receiving efficiency of the heat receiving plate decreases, and as a result, the final power generation efficiency also decreases. Therefore, the area of ​​the outer periphery is preferably less than 40%.

[0091] Here, the "area of ​​the outer periphery" refers to the area of ​​the part whose temperature is relatively lowered by the cooling means. For example, if the central part of the heat receiving plate is provided with black Ni plating as the temperature reducing means, this refers to the area of ​​the part where the black Ni plating is not provided. Also, if the surface roughness of the outer periphery is relatively low as the temperature reducing means, this refers to the area of ​​the region where the surface roughness is low.

[0092] To examine the effect of the outer peripheral area ratio, two thermoelectric generators were prepared and the durability of the sealing member was evaluated. Both thermoelectric generators were equipped with a heat receiving plate with black Ni plating in the center as a low-temperature means, and all had the same structure and materials except that the outer peripheral area of ​​one was 74% and the other was 64%. A thermal load test was conducted on the thermoelectric generators, in which the following (1) and (2) were alternately repeated. (1) The temperature of the heat receiving plate is raised to 250°C by radiant heating. (2) The radiation heating was stopped and the device was cooled to room temperature. During the heat load test, cooling water was flowed through the cooling plate at a flow rate of 20 L / min to maintain a low temperature. The power generation output line of the thermoelectric generator was connected to an electronic load device, and the amount of power generated was measured.

[0093] The results of the above tests showed that a thermoelectric generator with an outer peripheral area of ​​74% had a durability equivalent to approximately 10 years, and a thermoelectric generator with an outer peripheral area of ​​64% had a durability equivalent to approximately 20 years. Note that here, taking into consideration the operating rate when thermoelectric power is actually generated at a steelworks, durability was evaluated based on 20,000 cycles as equivalent to 20 years. In the above evaluation, it was determined that the limit had been reached when the output fell below 80% of the initial output.

[0094] On the other hand, when a similar test was conducted using a thermoelectric power generation device that was not equipped with a cooling means, the temperature of the heat-receiving surface of the sealing material reached a high temperature of approximately 290°C, and the sealing material deteriorated one month after use, allowing moisture to penetrate into the thermoelectric power generation module and causing a ground fault. In contrast, in the above thermoelectric power generation device equipped with a cooling means, the temperature of the heat-receiving surface of the sealing material was approximately 230°C when used at the same power generation output (165 W). In this way, by providing a cooling means, the temperature of the sealing material can be lowered and deterioration can be suppressed.

[0095] (Second embodiment) 3 is a cross-sectional schematic diagram showing the structure of a thermoelectric generator 1 according to a second embodiment of the present invention. In addition to the same configuration as the thermoelectric generator according to the first embodiment described above, the thermoelectric generator 1 according to this embodiment further includes an outer periphery sealing frame 34 between a pair of insulating substrates 31 of a thermoelectric power generation module 30, which seals the periphery of the pair of insulating substrates 31. The outer periphery sealing frame 34 is a resin or metal member, and is fixed by being sandwiched between the insulating substrates 31. By providing the outer periphery sealing frame 34 in addition to the sealing member 50 in this way, it is possible to more reliably prevent the intrusion of moisture and iron powder from the outside.

[0096] (Third embodiment) 4 is a cross-sectional view showing a structure of a thermoelectric generator 1 according to a third embodiment of the present invention. The thermoelectric generator 1 according to this embodiment has the same configuration as the thermoelectric generator according to the second embodiment described above, and further includes a support member 60.

[0097] More specifically, the support member 60 is placed between the insulating substrate 31 on the heat receiving plate 10 side and the heat receiving plate 10, with the upper surface of the support member 60 in contact with the lower surface of the insulating substrate 31 on the heat receiving plate 10 side, and the lower surface of the support member 60 in contact with the upper surface of the heat receiving plate 10. By placing the support member 60 in this way and filling the gap between the insulating substrate 31 and the heat receiving plate 10, it becomes easier to apply pressure to the peripheral sealing frame 34, further improving the sealing effect of these members.

[0098] The support member 60 is preferably provided in a frame shape so as to support the outer periphery of the thermoelectric power generation module 30. In particular, both the outer periphery sealing frame 34 and the support member 60 are frame-shaped, It is preferable that they are arranged at corresponding positions on the outer periphery of the thermoelectric power generation module 30 .

[0099] Furthermore, when the support member 60 is used, the heat conduction sheet 40 may be provided in a portion where the support member 60 is not present.

[0100] The structure of the parts not mentioned in the above description can be the same as that of the second embodiment shown in FIG.

[0101] (Fourth embodiment) Next, a fourth embodiment, which is a modification of the third embodiment, will be described with reference to Fig. 5. Note that the structure of parts not mentioned in the following description can be the same as that of the third embodiment shown in Fig. 4.

[0102] In the third embodiment shown in FIG. 4 , the support member 60 has a rectangular cross section. In the fourth embodiment shown in FIG. 5 , however, the support member 60 has a V-shaped cross section. In this example, a rod-shaped member with a V-shaped cross section is placed between the heat receiving plate 10 and the insulating substrate 31 on the heat receiving plate 10 side, with the apex of the V facing upward. This shape reduces the contact area between the support member 60 and the heat receiving plate 10 and the insulating substrate 31, thereby suppressing heat conduction. Furthermore, the V-shape creates an internal space, which further suppresses heat conduction. Specifically, because the peripheral sealing frame 34 is installed above the support member 60, the thermoelectric generating element 32 is not present. Therefore, heat transferred to the insulating substrate 31 through the support member 60 is not effectively utilized. Therefore, by using a support member 60 with a structure as shown in FIG. 5 to suppress heat transfer through the support member 60, the thermal energy transferred to the area where the thermoelectric generating element 32 is located is relatively increased, thereby improving power generation efficiency. [Explanation of symbols]

[0103] 1 Thermoelectric power generation device 10 Heat receiving plate 11 Central area (area other than the outer periphery) 12 Outer periphery 20 Cooling plate 30 Thermoelectric power generation module 31 Insulating substrate 32 Thermoelectric power generation element 33 electrode 34 Peripheral sealing frame 40 Thermal Conduction Sheet 50 Sealing member 60 Support member

Claims

1. A thermoelectric power generation device to be attached to a line of manufacturing equipment in a steelworks, A heat receiving plate; a cooling plate facing the heat receiving plate; a thermoelectric power generation module disposed between the heat receiving plate and the cooling plate; a sealing member annularly disposed between the heat receiving plate and the cooling plate so as to surround the thermoelectric power generation module, the sealing member is made of an insulating elastic material, The thermoelectric power generation device, wherein the heat receiving plate is provided with a cooling means for relatively lowering the temperature at the outer periphery of the heat receiving plate.

2. The thermoelectric power generating device according to claim 1 , wherein the temperature reducing means is configured to relatively lower the emissivity of an outer periphery of the heat receiving plate.

3. 3. The thermoelectric power generation device according to claim 2, wherein the temperature reducing means is configured to provide black Ni plating on a portion other than the outer periphery of the heat receiving plate, and not to provide black Ni plating on the outer periphery, thereby relatively lowering the emissivity of the outer periphery.

4. 3. The thermoelectric power generating device according to claim 2, wherein the temperature reducing means is configured to relatively reduce the emissivity of the outer periphery by relatively reducing the surface roughness of the outer periphery.

5. The thermoelectric power generation device according to any one of claims 2 to 4, wherein the temperature reducing means is configured to lower the emissivity of a portion of the heat receiving plate where the thermoelectric power generation module is not provided than that of a portion where the thermoelectric power generation module is provided.

6. The thermoelectric power generation device according to claim 1 or 2 is installed in a line of manufacturing equipment in a steelworks, A thermoelectric power generation method for converting heat into electric power by the thermoelectric power generation device.

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