JP2012169109A - Porous heating body, porous heating element, and gas decomposition element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous heating body, a porous heating element, and a gas decomposition element capable of efficiently heating flowing gas, performing thermal decomposition on the gas, and being used independently or in combination with another gas decomposition device.SOLUTION: A porous heating body 1 is made up of a metal porous body including continuous pores 1b, and in the porous heating body 1, a frame 10 that includes an outer shell made up of a heating material and a core part made up of a hollow and/or a conductive material has integrally continuous three-dimensional network structures.

Description

  The present invention relates to a porous heating element, a porous heating element, and a gas decomposition element. Specifically, the present invention relates to a porous heating element, a porous heating element, and a gas decomposition element suitable for a gas decomposition apparatus that thermally decomposes by flowing a gas.

  For example, ammonia is an indispensable compound for agriculture and industry, but is harmful to humans, so various methods for decomposing ammonia in water and air are known. In order to decompose and remove ammonia from water containing a high concentration of ammonia, a method has been proposed in which ammonia water is sprayed and contacted with an air stream to separate ammonia in the air and contacted with hypobromous acid solution or sulfuric acid. (Patent Document 1). In addition, a method of separating ammonia in the air by the same process as the above method and burning it with a catalyst (Patent Document 2) and a method of decomposing ammonia-containing wastewater into nitrogen and water using a catalyst have been proposed. (Patent Document 3). Furthermore, the waste gas of the semiconductor manufacturing apparatus often contains ammonia, hydrogen, etc., and in order to completely remove the odor of ammonia, it is necessary to remove it to the ppm order. For this purpose, many methods have been used in which harmful gas is absorbed in water containing chemicals through a scrubber when the waste gas of the semiconductor device is released. On the other hand, in order to decompose harmful gases at a low running cost without input of energy, chemicals, etc., a waste gas treatment method in a semiconductor manufacturing apparatus or the like that decomposes ammonia with a phosphoric acid fuel cell has been proposed (patent) Reference 4).

JP-A-7-31966 Japanese Patent Laid-Open No. 7-116650 Japanese Patent Laid-Open No. 11-347535 JP 2003-45472 A Japanese Patent No. 3238086

  A method using a chemical such as a neutralizing agent as described in Patent Document 1, a method of burning as described in Patent Document 2, and a thermal decomposition using a catalyst as described in Patent Document 3 Ammonia can be decomposed by a reaction method. However, these methods require chemicals and external energy (fuel), and further require periodic replacement of the catalyst, resulting in increased running costs.

  In addition, since the apparatus becomes large, it is difficult to secure a space when it is additionally provided in existing facilities. In addition, for the device that uses phosphoric acid fuel cells to remove ammonia in the exhaust gas from the production of compound semiconductors, the electrolyte is liquid, so the partition between the air side and the ammonia side cannot be made compact, and the size of the device is reduced. There was a problem that was difficult.

  In order to solve the above problem, as described in Patent Document 5, a cylindrical solid electrolyte layer, and a first electrode layer and a second electrode layer formed so as to sandwich the solid electrolyte layer from inside and outside A cylindrical MEA (Membrane Electrode Assembly) configured with the above can be employed. A gas containing a gas to be decomposed is caused to flow in the axial direction in the inner space of the cylindrical MEA.

  In order to decompose the gas, it is preferable that the temperature of the gas containing the gas is increased as much as possible to act on the first electrode layer (fuel electrode) of the cylindrical MEA. In order to obtain high gas decomposition performance, it is necessary to keep the cylindrical MEA at a high temperature, for example, 800 ° C. or higher. For this reason, the cylindrical MEA is accommodated in a heating container, and the entire cylindrical MEA is heated.

  However, since the surface area of the inner electrode of the cylindrical MEA is limited, it is difficult to process a large amount of gas, and the gas decomposition efficiency decreases when the gas flow rate is increased. In addition, when the gas flow rate is increased, the temperature of the gas in the cylindrical MEA decreases, and the decomposition efficiency further decreases.

  Further, when the flow rate is increased, the time during which the gas stays in the cylindrical MEA is reduced. For this reason, after the said gas is fully heated, the problem that it cannot make it act on the said cylindrical MEA also arises.

  The present invention provides a porous heating element, a porous heating element, and a gas that can efficiently heat and thermally decompose a gas, and can be used alone or in combination with another gas decomposition apparatus. It is an object to provide a decomposition element.

  The invention described in claim 1 of the present application is a porous heating element made of a metal porous body having continuous pores, and has a skeleton having an outer shell made of a heating material and a core made of a hollow or conductive material. However, it relates to what constitutes an integrally continuous three-dimensional network structure.

  Since the heating element according to the present invention is formed in a porous shape having continuous pores, the gas can flow in the pores and can be efficiently heated.

  In addition, since the porous heating element has a three-dimensional network structure, the porosity can be set extremely high. Thereby, the flow resistance of the gas in the pores is reduced, and a large amount of gas can be flowed and heated. Further, the skeleton is formed so as to be continuously integrated. Therefore, unlike a porous heating element configured by filling a fibrous heating element, contact resistance between adjacent fibers does not occur, and the electrical resistance in each part of the porous heating element changes greatly. There is no. Therefore, the current flow in the porous heating element is less unevenly distributed, and the entire porous heating element can be heated uniformly.

  The method for forming the skeleton is not particularly limited. For example, as in the invention described in claim 3, the skeleton can be formed by providing a plating layer or a metal coating layer on the surface of a three-dimensional network resin and eliminating the resin. By forming the outer shell of the skeleton from a metal plating layer or a metal coating layer, the thickness of the skeleton can be set very thin and uniform. Thereby, it becomes possible to form a porous heating element having a large porosity.

  The said core part is comprised including a hollow or / and electroconductive material according to a manufacturing method. For example, as described above, when the skeleton is formed by providing a plating layer on the surface of a three-dimensional network resin and erasing the resin, the portion where the resin has disappeared becomes hollow. In addition, when the surface of the three-dimensional network resin is coated with a conductive material to conduct the conductive treatment in order to provide the plated layer, the surface conductive layer made of the conductive material has a hollow core portion. It may remain on the inner peripheral surface. Furthermore, when a heat treatment or the like is performed after the plating treatment, the outer shell may shrink and the hollow portion may disappear. In addition, the structure of the said core part does not need to be uniform in the whole heat generating body, and may differ according to parts. For example, the conductive material constituting the core part may be melted by a subsequent heat treatment and unevenly distributed in the heat generating body, or a part of the hollow part may be lost. In addition, the thickness etc. of the said surface conductive layer are set so that the required heat generation performance of a porous heat generating body may not be inhibited.

  As in the invention described in claim 2, the three-dimensional network structure in the porous heating element has a plurality of branch portions constituting the skeleton gathered together at a knot portion and integrally continuous. It is preferable that the thickness of the outer shell of each branch portion gathered at the nodule portion is substantially constant. Since the current from each skeleton (branch part) concentrates in the above-mentioned nodal part, if the electric resistance of each branch part gathering in one nodule part is different, an excessive current flows in some of the branch parts around the nodule part. As a result, the temperature rises and the skeleton may melt or deteriorate. By setting the thickness of the outer shells of the branches that gather in one nodule part to be almost constant, there is no significant difference in the electrical resistance of each skeleton that gathers in one nodule part. An excessive current does not flow through some skeletons. Thereby, it becomes possible to prevent fusing and deterioration of the skeleton.

  The thickness of the outer shell of the branch portion gathering at one nodule portion of the porous heating element only needs to be substantially constant, and it is not required until the thickness of the outer shell of the entire heating element is constant. For example, depending on the manufacturing method, the thickness of the outer shell may be different between the surface layer portion of the heating element and the inside. In this case, the outer shell thickness of each branch portion gathering at the nodal portion of the surface layer portion and the outer shell thickness of the branch portion gathering at the inner nodal portion are different. However, if the thickness of the skeleton gathered at each nodule portion is substantially constant, an excessive current will not flow through some branches, and the skeleton near the nodule portion can be prevented from fusing. Moreover, since the skeleton around the nodule portion has an equal strength, the strength can be ensured.

  Further, when the outer shell is formed from a plating layer or a coating layer by the method described in claim 3, the thickness of the outer shell of the skeleton gathered at one nodule portion can be formed almost constant. Thereby, a big difference does not arise in the electrical resistance of the outer shell around one nodule, and the entire region of the porous heating element can be heated uniformly.

  The material which comprises the said outer shell which is a heat generating body is not specifically limited. For example, as in the invention described in claim 4, it is preferable to form an alloy containing 67 to 95% of Ni and 5 to 33% of Cr. By setting the blending amount within the above range, the porous heating element can be efficiently heated. Other components may be blended while maintaining the blending ratio of Ni and Cr.

  When the outer shell is formed from a coating layer, a porous heating element can be formed by directly coating and firing a material containing Ni and Cr constituting the heating element on the surface of the three-dimensional network resin. On the other hand, it is difficult to directly form a Ni—Cr alloy plating layer. In a fifth aspect of the present invention, the porous heating element is alloyed by diffusing Cr in a metallic porous body mainly composed of Ni.

  The invention described in claim 5 is a Ni-Cr alloy that first forms a porous body from Ni and diffuses Cr from the surface of Ni constituting the porous body to function as a heating element. is there.

  Since Ni is easily plated, the skeleton can be easily formed. Also, various metal porous bodies having different skeleton thicknesses and porosity can be easily configured. And by making this Ni porous body into a Cr alloy, various heating elements having required electrothermal characteristics can be configured.

  The method for forming the Ni porous body into a Cr alloy is not particularly limited. For example, the Ni porous body is made into a Ni-Cr alloy by heat-treating the Ni porous body in a mixed gas of a diffusion permeation component gas generated by heating the Cr source powder and a reducing dilution gas. Can do.

  Further, as in the invention described in claim 6, the second outer shell made of Cr is laminated on the first outer shell made of Ni, and a predetermined heat treatment is performed, whereby the first outer shell is formed. One outer shell and the second outer shell are diffused and alloyed with each other to form the porous heating element.

  In order to generate heat in the porous heating element, it is necessary to energize the porous body. On the other hand, when the porosity is high, it is difficult to connect the wiring via a sufficient connection area. It is also difficult to ensure the connection strength of the wiring. If the connection area between the current-carrying wiring and the porous heating element is small, the current value in the vicinity of the wiring will increase locally and the amount of heat generated in that area will increase, which may damage the porous heating element and wiring. There is sex.

  In order to avoid the inconvenience, as in the invention described in claim 7, a heat generating part is formed using the porous heat generating element described in claims 1 to 6, and the heat generating part has a predetermined area. It is preferable to form a porous heating element by providing a lead portion that is connected and introduces a current.

  By providing the lead portion connected to the porous heating element through a sufficient connection area, the entire porous heating element can be energized to generate heat. Moreover, since the porous heating element can be efficiently energized only by connecting the wiring to the lead portion, the handleability is also improved. The form of the lead part and the connection area can be set according to the form and dimensions of the porous heating element. For example, the lead portion can be provided by pressure-welding or welding a conductive metal plate having a predetermined area over a predetermined area of the porous heating element.

  Further, the lead portion can be configured by including a conductive metal porous body connected to the porous heating element. For example, a porous metal body having a porosity similar to that of the porous heating element is connected over a predetermined area of the porous heating element, and wiring is connected to the porous metal body. A current can be smoothly supplied into the heat generating body. The metallic porous body can be connected to the porous heating element by bringing it into contact with or welding at a predetermined pressure over a predetermined area of the porous heating element.

  The metal porous body constituting the lead portion is preferably formed of a conductive material that does not generate heat even when energized. For example, the lead portion can be formed from a metal porous body having a low electrical resistance such as Ni or copper. Further, when the lead portion is formed from the metal porous body, a cooling effect in the lead portion can be expected. This makes it possible to reduce the amount of heat conducted from the porous heating element to the wiring or the like, and to reduce the temperature acting on the wiring or the like. In addition, it is possible to easily connect a wiring or the like to the lead portion, and the handleability of the porous heating element is improved.

  As in the ninth aspect of the invention, the heat generating portion and the lead portion can be integrally formed by alloying the intermediate portion of the porous metal body constituting the lead portion. For example, Ni is used to form a common skeleton constituting the porous heating element and the lead portion as a plating layer on the surface of the porous resin. Next, masking or the like is performed on the portion constituting the lead portion, and a Cr plating layer is formed only on the portion corresponding to the heat generating portion. Thereafter, by removing the porous resin and performing heat treatment, a part of the Ni skeleton can be made into a Cr alloy and the lead portion can be integrally formed.

  By adopting the above configuration, it is possible to form a porous heating element in which the same skeleton constituting the porous body is continuous and a required portion can be heated. In addition, it is possible to efficiently energize the heat generating part, and since the lead part has heat dissipation, it is possible to reduce the temperature acting on the wiring and the like. In addition, the lead portion can have the same air permeability as the heat generating portion, and a gas decomposition element suitable for a gas decomposition element or the like can be configured.

  According to a tenth aspect of the present invention, there is provided the porous heating element according to any one of the first to sixth aspects, a container filled with the porous heating element, the heating element connected to the heating element in a predetermined area, and the container A gas decomposing element comprising: a lead part having a wiring led out to the outside; and a gas to be decomposed flowing in the porous heating element set at a predetermined temperature by energizing through the lead part It is.

  Since the gas decomposition element according to the present invention is configured such that the gas used for decomposition flows in the porous heating element that generates heat by itself, it is possible to efficiently heat and decompose the gas. . The gas decomposition device according to the present invention can constitute a gas decomposition apparatus alone or in combination with other gas decomposition devices. For example, an efficient gas decomposition apparatus can be configured in combination with a gas decomposition element including a cylindrical MEA.

  Since the porous heating element can be heated uniformly, a large amount of gas can be efficiently heated and decomposed.

It is an electron micrograph which shows the external appearance structure of the porous heat generating body which concerns on this invention. It is a figure which shows typically the cross-sectional structure of the nodule part vicinity of the porous heat generating body which concerns on this invention. It is sectional drawing which follows the III-III line in FIG. It is a schematic sectional drawing of the porous heat generating element comprised by providing a lead part in the porous heat generating body which concerns on this invention. It is a schematic sectional drawing of the porous heat generating element which concerns on 2nd Embodiment. It is a figure which shows the manufacturing process of the porous heat generating element shown in FIG. It is a figure which shows the manufacturing process of the porous heat generating element shown in FIG. It is a figure which shows the manufacturing process of the porous heat generating element shown in FIG. It is a figure which shows the manufacturing process of the porous heat generating element shown in FIG. It is a figure which shows the manufacturing process of the porous heat generating element shown in FIG. It is a figure which shows the manufacturing process of the porous heat generating element shown in FIG. It is a figure which shows the manufacturing process of the porous heat generating element shown in FIG. It is sectional drawing which accommodated the porous heat generating body in the container, and comprised the gas decomposition | disassembly element. It is the schematic of the gas decomposition apparatus comprised combining the gas decomposition element shown in FIG. 13, and another gas decomposition element.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

  FIG. 1 is an electron micrograph showing the external structure of a porous heating element 1 according to the present invention. The porous heating element 1 has a three-dimensional network structure having continuous pores 1b. As shown in FIG. 2, the three-dimensional network structure has a form in which triangular prism-like skeletons 10 are continuously connected in three dimensions, and a plurality of branch parts 12 constituting the skeleton are gathered at a nodule part 11. It has an integrally continuous form. Each part of the skeleton 10 includes an outer shell 10a and a hollow core part 10b as shown in FIG. In the embodiment shown in FIGS. 2 and 3, in the outer shell 10a, as will be described later, the plating layer 12a and the surface conductive layer 12b are integrally alloyed to function as a heating element. It is configured.

  Since the porous heating element 1 is formed in a porous shape having continuous pores 1b, the gas can flow in the pores 1b and can be efficiently heated. In addition, the porous heating element 1 can have a very high porosity by adopting a three-dimensional network structure. For this reason, the flow resistance of the gas in the pores is low, and a large amount of gas can be flowed and heated.

  In addition, as shown in FIG. 2, the thickness t of the outer shell 10a of the branch portion 12 gathering at one nodule portion 11 in the three-dimensional network structure is formed to be substantially constant. Since the thickness t of the outer shells of the branches (skeleton) gathering at one nodule is substantially constant, there is no significant difference in the electrical resistance of each branch 12 gathering at one nodule. An excessive current does not flow through some branches gathering at the nodule. Thereby, it becomes possible to prevent fusing and deterioration of the skeleton.

  It should be noted that the thickness of the outer shell 10a of the branch portion 12 (skeleton) that gathers at one node portion 11 of the porous heating element 1 only needs to be substantially constant, and the thickness of the outer shell of the entire heating element is constant. It is not required. For example, depending on the manufacturing method, the thickness of the outer shell may be different between the surface layer portion of the heating element and the inside. In this case, the outer shell thickness of each skeleton gathering at the nodal portion of the surface layer portion is different from the outer shell thickness of the skeleton gathering at the inner nodal portion. However, if the thickness of the outer shells of the branches gathering at one nodule is almost constant, an excessive current will not flow through at least some branches around each nodule, and the skeleton near the nodule It can prevent fusing or deterioration.

  The porous heating element 1 according to this embodiment is formed of an alloy containing at least Ni and Cr. The blending amount of Ni and Cr can be set according to the required calorific value. For example, the outer shell 10 of the porous heating element 1 can be formed from an alloy containing 67 to 95% Ni and 5 to 33% Cr.

  The porous heating element 1 can be formed using various methods. For example, the porous heating element can be formed by directly coating the material constituting the porous heating element on the surface of the three-dimensional network resin and baking it. Further, when the skeleton is formed by plating, the method includes a step of conducting a conductive treatment on the three-dimensional network resin, a step of metal plating the three-dimensional network resin, and a step of removing the three-dimensional network resin. Can consist of

  As a form of the three-dimensional network resin, a resin foam, a nonwoven fabric, a felt, a woven fabric, or the like can be used. Although the raw material which comprises the said three-dimensional network resin is not specifically limited, It is preferable to employ | adopt what can be lose | disappeared by heating etc. after metal plating etc. Moreover, in order to ensure workability and handling property, it is preferable to employ a flexible one. In particular, it is preferable to employ a resin foam as the three-dimensional network resin. The resin foam may be a porous material having continuous pores, and a known one can be adopted. For example, a foamed urethane resin, a foamed styrene resin, or the like can be used. There are no particular limitations on the pore shape, porosity, dimensions, and the like of the foamed resin, and they can be set as appropriate according to the application.

  In the case where a porous heating element is formed by plating, the treatment for making the three-dimensional network resin conductive is performed for providing a metal plating layer constituting the skeleton on the surface of each pore. If surface conductive layer 12b in 2 can be provided, it will not be limited in particular. For example, when nickel is used, an electroless plating process, a sputtering process, or the like can be employed. In addition, when adopting metals such as titanium and stainless steel, carbon black, graphite, etc., it is possible to employ a treatment of impregnating and applying the mixture obtained by adding a binder to these fine powders to the three-dimensional network resin. it can.

  The plating treatment is not particularly limited, and the treatment can be performed by a known plating method. For example, when nickel plating is employed, it is preferable to employ an electroplating method from the viewpoint of productivity, cost, and the like. A well-known or commercially available thing can be employ | adopted as a plating bath used for electroplating.

The thickness (weight per unit area) of the plating layer is not particularly limited. It can be set in consideration of the required porosity and strength. For example, it is possible to employ a unit weight of ^{100g / m 2 ~2000g / m 2} .

  After the plating layer is formed, a step of removing the three-dimensional network resin is performed. The step of removing the three-dimensional network resin may be performed by, for example, heat-treating the porous body provided with the plating layer at 600 ° C. to 800 ° C. in an oxidizing atmosphere such as air in a stainless muffle. Dimensional network resin can be removed by incineration.

  In order to obtain high heat generation performance, it is preferable to form the porous heating element from a Ni alloy having a large amount of Cr component. It is difficult to directly form the plating layer from an alloy material of Ni—Cr. For this reason, for example, it is possible to employ a technique in which a Ni plating layer and a Cr plating layer are separately formed and then alloyed. That is, a Ni plating layer is first formed on the three-dimensional network resin by the above-described method, and a Cr plating layer is laminated thereon. Thereafter, the three-dimensional network resin is removed and further heat-treated at a predetermined temperature, whereby the Cr plating layer and the Ni plating layer can be diffused and alloyed.

The thickness of the Cr plating layer (basis weight) also is not particularly limited, for example, can be set in a range of ^{10g / m 2 ~1000g / m 2} .

The Cr plating is performed by heat-treating the porous body in which the Cr plating layer and the Ni plating layer are laminated in a stainless steel muffle at 800 ° C. to 1000 ° C. in a reducing gas atmosphere such as CO or H _2. The Ni—Cr alloy layer can be formed by diffusing the layer and the Ni plating layer. Further, in an inert gas atmosphere such as N ₂ or Ar, an alloy layer can be formed from the Cr plating layer and the Ni plating layer by heating to 1000 ° C. to 1500 ° C. in a carbon muffle. When the surface conductive layer 12b shown in FIG. 2 and FIG. 3 is provided by Ni, the surface conductive layer 12b is also Ni—Cr alloyed in the alloying step, and the whole becomes a heating element.

  By adopting the above steps, it is possible to form a porous heating element having little variation in chromium concentration in the outer shell, high corrosion resistance and high heat generation characteristics. Further, since the outer shell is constituted by the plating layer, the thickness (cross-sectional area) of the outer shell can be set almost uniformly in the porous body. For this reason, the dispersion | variation in the electrical resistance in a porous body decreases, and the whole porous body can be heated uniformly by supplying with electricity. In the above-described embodiment, the skeleton is formed by plating a three-dimensional network resin. However, the skeleton may be formed by coating a powder metal and then performing a heat treatment. In this case, a Ni—Cr alloy can be formed at a time by coating a powder containing Ni powder and Cr powder and then firing.

  As shown in FIG.2 and FIG.3, although the said core part which concerns on this embodiment is formed in hollow shape, it is not limited to this. That is, in the above-described embodiment, the surface conductive layer 12b formed of Ni is integrated with the outer shell because the Cr alloy is formed. However, when the surface conductive layer is formed of another conductive material, the core It may remain as a part. For example, when the surface conductive layer is formed of titanium, carbon, or the like, and the skeleton is formed by Ni plating and then Cr alloyed, the surface conductive layer 10c remains as a core without being alloyed. Become. Further, in the heat treatment step of forming the Ni plating layer into a Cr alloy, the outer shell may shrink and the hollow core portion may disappear. In addition, the thickness etc. of the said surface conductive layer are set so that the required heat generation performance of a porous heat generating body may not be inhibited.

  As shown in FIG. 1, the porous heating element 1 according to the present embodiment has a very high porosity, so it is difficult to connect a wiring for energization. That is, if the connection area of the portion for introducing current to the porous heating element 1 is small, the current value in the vicinity of the introduction portion is locally increased to increase the amount of heat generation, which may damage the wiring and the like. In order to avoid the above inconvenience, it is preferable to provide a lead portion connected to the porous heating element 1 in a wide area. For example, a conductive metal plate with a predetermined area can be welded to a porous heating element, and a wiring can be connected to the metal plate to energize.

  In the embodiment shown in FIG. 4, the porous heat generating element 2 is configured by providing lead portions 3 and 4 in the porous heat generating portion 2a. The porous heating element 2 includes a long porous heating element 2a having a predetermined cross-sectional area, metal porous bodies 3a and 4a having one end connected to the end face of the porous heating element 2a, It comprises electrode plates 3b and 4b connected to the other ends of the metal porous bodies 3a and 4a. By connecting the wiring 5 to the electrode plates 3b and 4b, the porous heating element 2a is energized through the lead portions 3 and 4.

  The metal porous bodies 3a and 4a are preferably formed from a material having a low electric resistance such as Ni or Cu. Moreover, the form of the metal porous bodies 3a and 4a is not particularly limited. For example, it can also be comprised from the metal porous body formed by the same method as the said porous heat generating body 2a, and can also be comprised from the metal porous body of another form.

  The connection form between the porous heating element 2a and the metal porous bodies 3a and 4a is not particularly limited. For example, a predetermined pressure can be applied for pressure contact. It can also be connected by welding. The connection area can be set according to the density of the porous heating element, the flowing current value, and the like.

  There are no particular limitations on the materials and connection methods of the electrode plates 3b and 4b. For example, a Ni plate or a Cu plate can be connected to the metal porous bodies 3a and 4a by welding.

  By providing the lead portions 3 and 4, it is possible to secure a connection area with respect to the porous heating element 2a, and to energize the porous heating element 2a through a wide area. For this reason, a large current does not flow locally, and the porous heating element can be heated uniformly.

  On the other hand, the metal porous bodies 3a and 4a are preferably configured so as not to generate heat by setting the electric resistance to be small. Moreover, since it is porous, it can also be expected to dissipate heat transmitted from the porous heating element 2a. As a result, it is possible to set the electrode plates 3b and 4b so that a high temperature does not act on the electrode plates 3b and 4b. 4b can be easily connected.

  FIG. 5 shows a schematic structure of the porous heating element 202 according to the second embodiment. In the porous heating element 202 according to this embodiment, the metal porous body 203a, 204a constituting the lead portions 203, 204 and the porous portion are formed by forming a Cr alloy at the intermediate portion of the metal porous body formed of Ni. The heat generating part 202a is integrally formed, and electrode plates 203b and 204b similar to the embodiment shown in FIG. 2 are provided at both ends.

  By adopting the above configuration, it is not necessary to connect a separately formed metal porous body to the porous heat generating portion 2a. Moreover, the metal porous bodies 203a and 204a and the porous heat generating portion 202a constituting the lead portions 203 and 204 are configured to have the same skeleton structure and are integrally continuous. For this reason, the connection resistance of these members does not occur, and the porous heat generating portion 202a can be energized efficiently.

  The porous heating element 202 having the above configuration can be formed by, for example, the method shown in FIGS. 6 to 12 schematically show a method for manufacturing the porous heating element 202. First, in order to form a common skeleton of the metal porous bodies 203a and 204a and the porous heating element 202a constituting the lead portions 203 and 204, a three-dimensional network resin 210 shown in FIG. 6 is prepared. The three-dimensional network resin 210 includes a portion 210a corresponding to the hollow core portion constituting the skeleton and the continuous pores 210b. For example, the urethane resin is foamed with a predetermined porosity. Can be formed.

As shown in FIG. 7, the surface of the three-dimensional network resin 210 is subjected to a conductive treatment by the above-described method, and then a Ni plating layer 211 is formed. The Ni plating layer 211, as described above, can be formed by unit weight of ^{100g / m 2 ~2000g / m 2} . Thereafter, as shown in FIG. 8, a masking layer 212 for the Cr plating treatment is formed on the portion 204a constituting the lead portion. The masking layer 212 can be formed of, for example, an epoxy resin.

  Next, as shown in FIG. 9, a Cr plating layer 213 is provided on the porous body provided with the masking layer 212 by the method described above. Since the masking layer 212 is provided, the Cr plating layer 213 is formed only in a region corresponding to the porous heat generating portion 202a. As a result, a composite plating layer 220 in which a Ni plating layer and a Cr plating layer are laminated is formed in a portion constituting the heat generating portion 202a.

  After removing the masking layer 212 (FIG. 10), the above-described step of removing the three-dimensional network resin is performed, and as shown in FIG. 11, a composite plating layer comprising a Ni plating layer 211 and a Cr plating layer 213 is provided. A three-dimensional network porous metal body 214 made of 220 is formed.

  The metal porous body 214 including the composite plating layer 220 is heat-treated at 800 ° C. to 1000 ° C. in a reducing gas atmosphere such as CO or H 2 in a stainless steel muffle, whereby the Ni plating layer 211 and the above The components constituting the Cr plating layer 213 can be diffused to form an Ni—Cr alloy to form the metal porous body shown in FIG. As shown in FIG. 12, the metal porous body has a skeleton composed of a hollow core portion 201c and an outer shell 201a.

  By adopting the above-mentioned method, the intermediate part of the metal porous body formed of Ni is Ni-Cr alloyed, and the heat generating part 202a and the metal porous bodies 203a and 204a not Cr alloyed on both sides are provided. The porous metal body can be formed integrally. By providing the electrode plates 203b and 204b on both sides of the metal porous bodies 203a and 204a, the porous heating element 202 shown in FIG. 10 is formed.

  In the porous heating element 202, the lead portion including the metal porous body is formed. However, only the heating portion 202a is formed without forming the metal porous bodies 203a and 204a, and the heating portion 202a is configured. The lead portions may be provided by welding the electrode plates 203b and 204b directly to the porous body.

  FIG. 13 schematically shows a cross section of a gas decomposition element formed using the porous heating element according to the present invention.

  The gas decomposition element 310 is configured by filling a porous heating element 320 inside a long cylindrical container 309. The cylindrical container 309 is configured such that at least the inner surface has electrical insulation. For example, a cylindrical container made of ceramic can be employed.

  The porous heating element 320 according to the present embodiment includes a porous heating element 302 and lead portions 303 and 304 provided on both sides. The porous heating element 302 is formed in the same manner as in the first embodiment, and includes a three-dimensional network skeleton 302a formed of a Ni—Cr alloy and continuous pores 302b. .

  The lead portions 303 and 304 are metal porous bodies 303a and 304a connected to both ends of the porous heating element 302, and an annular shape disposed so as to surround the outer peripheral portions of the metal porous bodies 303a and 304a. It comprises an electrode part 303b, 304b.

  The metal porous bodies 303a and 304a are pressure-welded or welded to the end face of the porous heating element 302. The electrode parts 303b and 304b are also pressed or welded to the outer peripheral parts of the metal porous bodies 303a and 304a.

  A wiring 305 connected to the electrode portions 303b and 304b is drawn from the container 309 and connected to a power source 306. The wiring 305 energizes the porous heating element 320.

  The porous heat generating element 320 according to the present embodiment has high air permeability because the entire structure including the lead portions 303 and 304 is porous. The electrode portions 303b and 304b are also arranged so as to be attached to the inner peripheral surface of the end portion so as not to hinder the flow of gas in the cylindrical container. For this reason, the gas is introduced into the cylindrical container via the gas inlet 307 of the cylindrical container 309, the inside of the porous heating element 320 is caused to flow in the axial direction, and is discharged from the gas outlet 308. be able to. Further, since the porous heating element 302 is heated almost uniformly, the flowing gas can be heated uniformly. For this reason, gas can be decomposed | disassembled very efficiently. In addition, since it is not necessary to provide a heat source outside, the energy efficiency is very high.

  FIG. 14 is a schematic cross-sectional view of a gas decomposition apparatus 600 configured by combining a first gas decomposition element 410 and a second gas decomposition element 520 including a cylindrical MEA 510. The first gas decomposition element 410 has the same configuration as the gas decomposition element shown in FIG.

  The second gas decomposing element 520 includes a cylindrical MEA 510 that causes the inner gas to flow and decomposes, and a cylindrical container 509 that holds the cylindrical MEA 510 and allows air to flow to the outer peripheral portion of the cylindrical MEA. And is configured.

  The cylindrical MEA 510 includes a cylindrical solid electrolyte layer (not shown), a first electrode layer formed on the inner periphery of the solid electrolyte layer, and a second electrode formed on the outer periphery of the solid electrolyte layer. The electrode layer is provided.

  The cylindrical MEA 510 is held in the cylindrical container 509 so as to be connected between the gas inlet 507 and the gas outlet 508 of the cylindrical container 509. The outer periphery of the cylindrical container 509 is provided with an air inlet 517 for introducing air and an outlet 518 for discharging the air that has flowed through the outer periphery of the cylindrical MEA 510.

  A heater (not shown) is provided on the outer periphery of the gas decomposition element 520 so that the space in which the cylindrical MEA 510 and the air flow can be heated to a predetermined temperature. Further, a wiring (not shown) is provided between the first electrode layer and the second electrode layer of the cylindrical MEA 510, and a load device (not shown) is provided in the wiring.

  The first gas decomposing element 410 and the second gas decomposing element 520 are connected to each other via a connection portion 500, and the gas to be decomposed is the first gas decomposing element 410 and the second gas. It is made to flow sequentially to the decomposition element 520.

  The gas decomposition apparatus 600 having the above configuration decomposes gas by heating in the first gas decomposition element 410, while the gas that cannot be decomposed by the first gas decomposition element 410 in the second gas decomposition element 520. Is configured to be decomposed electrochemically.

For example, when decomposing ammonia gas, the ammonia gas is thermally decomposed in the first gas decomposing element, as in 2NH ₃ → N ₂ + 3H ₂ .

In the first electrode layer (anode) of the cylindrical MEA 510,
(Anode reaction) “2NH ₃ + 3O ^{2 −} → N ₂ + 3H ₂ O + 6e ⁻ ”
The reaction of More specifically, a reaction of 2NH ₃ → N ² + 3H ₂ occurs in a part of ammonia, and this 3H ₂ reacts with oxygen ions 3O ²⁻ to generate 3H ₂ O.
On the other hand, in the second electrode layer (cathode) of the cylindrical MEA,
(Cathode reaction) “O ₂ + 4e ⁻ → 2O ²⁻ ”
The reaction of
As a result of the electrochemical reaction, electric power is generated, a potential difference is generated between the first electrode layer and the second electrode layer, and current flows through the wiring. Thereby, electric power can be supplied to a load such as a heater connected in the wiring.

  By configuring the gas decomposition apparatus 600 by combining the first gas decomposition element 410 and the second gas decomposition element 520, the gas can be decomposed with high accuracy.

  The scope of the present invention is not limited to the embodiment described above. The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  In a gas decomposition apparatus or the like, gas can be efficiently heated and thermally decomposed.

DESCRIPTION OF SYMBOLS 1 Porous heating element 10 Skeleton 10a Outer shell 1b Continuous pore 2 Porous heating element 2a Heat generating part 3 Lead part 3a Metal porous body 3b Electrode plate 4a Metal porous body 4b Electrode plate 5 Wiring 11 Knot part 12 Branch part 202 Porous Heat generating element 202a Heat generating part 203 Lead part 203a Metal porous body 203b Electrode plate 204a Metal porous body 204b Electrode plate 205 Wiring

Claims (10)

A porous heating element comprising a porous metal body having continuous pores,
A porous heating element in which a skeleton having an outer shell made of a heat generating material and a hollow or / and a core made of a conductive material constitutes an integrally continuous three-dimensional network structure.   In the three-dimensional network structure, a plurality of branches constituting the skeleton gather together at a knot and are integrally continuous, and the thickness of the outer shell of each branch gathered at one knot is substantially equal. The porous heating element according to claim 1, which is constant.   The porous structure according to any one of claims 1 and 2, wherein the skeleton is formed by providing a plating layer or a metal coating layer on a surface of a three-dimensional network resin and eliminating the resin. Quality heating element.   The porous heating element according to any one of claims 1 to 3, wherein the outer shell is made of an alloy containing 67 to 95% of Ni and 5 to 33% of Cr.   The porous heating element according to any one of claims 1 to 4, wherein the outer shell is alloyed by diffusing Cr in a metal porous body mainly composed of Ni. .   The outer shell is formed by laminating a second outer shell made of Cr on a first outer shell made of Ni, and then performing a predetermined heat treatment to thereby form the first outer shell and the first outer shell. The porous heating element according to any one of claims 2 to 5, wherein the porous outer heating element is formed by diffusing and alloying two outer shells. A heating part formed from the porous heating element according to claim 1;
A porous heating element, wherein the heating part is connected with a predetermined area and is provided with a lead part for introducing a current.   The porous heating element according to claim 7, wherein the lead portion includes a conductive metal porous body connected to the porous heating element.   The porous part according to claim 7 or 8, wherein the heat generating part and the lead part are integrally formed by alloying an intermediate part of the metal porous body constituting the lead part. Quality heating element. The porous heating element according to any one of claims 1 to 6,
A container filled with the porous heating element;
A lead part having a wiring connected to the heating element with a predetermined area and drawn out of the container;
A gas decomposing element for flowing a gas to be decomposed into the porous heat generating body set to a predetermined temperature by energizing through the lead portion.

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