JP5765664B2 - Gas decomposition apparatus and power generation apparatus - Google Patents

Description

  The present invention relates to a gas decomposition apparatus and a power generation apparatus. Specifically, the present invention relates to a gas decomposition apparatus capable of efficiently decomposing a predetermined gas and a power generation apparatus including the gas decomposition apparatus.

  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. For this reason, the heater which heats the whole said cylindrical MEA is provided.

  In the conventional cylindrical MEA, a connection member is connected to both ends so that gas flows in one direction in the internal space of the cylindrical MEA. However, as described above, since the entire tubular MEA is kept at a high temperature, the sealing performance between the both ends of the tubular MEA and the connecting member is likely to be lowered, and the connection reliability is low. was there.

  Moreover, since the whole gas decomposition element containing the said cylindrical MEA will be provided in the heating container provided with the said heater, high heat resistance is requested | required also for the said connection member and the connection piping connected to this. Will be. For this reason, it is necessary to form the sealing structure and connection piping between these with expensive heat-resistant material, and increase the manufacturing cost of an apparatus.

  According to the present invention, the temperature of the gas flowing in the cylindrical MEA can be increased to further improve the decomposition efficiency, and the external piping, the connecting member connecting the external piping, and the seal structure provided therebetween are damaged by heat. It is an object of the present invention to provide a gas decomposition apparatus that can prevent the above-described problem and further reduce the manufacturing cost.

The present invention includes a cylindrical solid electrolyte layer, a first electrode layer formed on the inner periphery of the solid electrolyte layer, and a second electrode layer formed on the outer periphery of the solid electrolyte layer. A gas decomposition apparatus configured using a tubular MEA (Membrane Electrode Assembly) having a connecting member that allows a first gas to enter and exit the tubular MEA, and accommodates and heats the tubular MEA In addition, a heating container that allows the second gas to flow , and one end of the cylindrical MEA are provided sealed, a sealing part that is disposed in the heating container, and an internal space of the cylindrical MEA. A gas induction pipe that is inserted and forms a cylindrical flow path between the inner peripheral surface of the cylindrical MEA, and a cooling means that cools the connecting member and / or the protruding portion. , Gas induction above A gas introduction part that communicates with the pipe, and an annular exhaust space that surrounds an outer peripheral part of the gas induction pipe and has a gas discharge part on a side part; The gas introduced into the pipe is caused to flow toward the sealing portion, and is caused to flow reversely by flowing out of the induction pipe in the vicinity of the sealing portion, so that the cylindrical flow path is formed in the gas induction pipe. The first electrode layer is decomposed by being caused to flow in the direction opposite to the direction of the flow and discharged through the connecting member.

In the gas decomposition apparatus according to the present invention, 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 more. For this reason, while the said heating container is provided, cylindrical MEA is accommodated in the said heating container.

  In the present invention, the cylindrical MEA is provided with a protruding portion that protrudes downward and outward from the heating container, and the connecting member is provided at the tip of the protruding portion. That is, the connection member is provided outside the heating container and at a position away from the heating container. With this configuration, the temperature conducted from the cylindrical MEA in the heating container to the connecting member is lowered. Moreover, in the present invention, since the connecting member is provided below the heating container, it is not exposed to high-temperature air that convects the outside of the heating container. Therefore, it is possible to prevent the sealing performance between the cylindrical MEA and the connecting member from being lowered and to prevent gas leakage and the like. In addition, high heat resistance is not required for the connecting member and the pipe connected thereto, so that the connection reliability is increased and the manufacturing cost can be reduced.

The configuration of the protruding portion is not particularly limited . The protruding portion can be configured by protruding a part of the cylindrical MEA from the heating container.

Moreover , a part or all of the projecting part can be formed from the cylindrical MEA and a separate member. For example, a cylindrical ceramic member continuous with the cylindrical MEA can be connected to an end of the cylindrical MEA to form the protruding portion.

It is preferable that the separate member constituting the protruding portion is formed of a material having heat resistance and heat insulation. However, heat insulation is not essential. That is, various materials can be employed as long as the temperature acting on the connecting member can be reduced. For example, a ceramic having high heat resistance and high heat insulation can be employed. Further, when the protruding portion is formed of a metal material such as nickel, the heat transmitted from the cylindrical MEA is released at the protruding portion, and the temperature acting on the connecting member or the piping member is reduced. You can also

Further, a cooling means for cooling the protruding portion is provided . The configuration of the cooling means is not particularly limited. For example, a radiating fin or the like can be provided on the protruding portion. In addition, cooling can be performed by using cooling air or cooling water in the protruding portion.

Moreover , the said cooling means can be comprised so that the said connection member and / or the said protrusion part may be cooled using the 2nd gas before flowing in into the said heating container. In many cases, air is used as the second gas, and the air is introduced into the heating container by a fan, suction means, or the like, and is allowed to flow at a predetermined flow rate. For this reason, a very efficient cooling means can be comprised by utilizing the said 2nd gas.

  The structure of the cooling means using the second gas is not particularly limited. For example, the flow path of the second gas can be arranged around the connecting member and / or the protruding portion, and these portions can be configured to be exposed to the second gas that is allowed to flow at the outside air temperature. .

  In particular, when the projecting portion is formed of a separate member from the cylindrical MEA, the cooling fin and the second gas flow path can be integrally formed with the projecting portion.

The temperature of the upper Symbol projecting tip, preferably set to 260 ° C. or less. The means for setting the temperature range is not particularly limited. For example, the temperature can be controlled by providing a temperature sensor in the projecting portion or the connecting member and providing the cooling means that can be controlled by the control means. Moreover, the said temperature can also be set by adjusting the length of the said protrusion part according to the temperature of a heating container, or ambient temperature. The set temperature can be set according to the heat resistance of the seal structure between the connection members and the heat resistance of the connection members and the connection pipes.

  By adopting the above configuration, it is possible to reliably prevent the sealing structure between the cylindrical MEA and the connection member and the connection member itself from being damaged by heat. Moreover, it becomes possible to employ | adopt a member with low heat resistance for the said connection member or piping member, and can reduce manufacturing cost.

By providing the protrusion and the cooling means, the temperature acting on the connecting member can be greatly reduced. Thereby , the connection member can be formed from a resin material. The kind of the resin material is not particularly limited. For example, a fluororesin can be used. In addition, by forming the connecting member from a resin material, it is possible to easily perform processing and the like, and the manufacturing cost can be reduced.

In the present invention, the cylindrical MEA is provided with one end sealed, and is inserted into the sealing portion disposed in the heating container and the internal space of the cylindrical MEA. A gas guide pipe that forms a cylindrical flow path between the inner peripheral surface of the MEA and the gas introduced into the gas guide pipe via the connection member is directed toward the sealing portion. The first electrode while flowing in the direction opposite to the flow in the gas induction pipe by causing it to flow reversely by flowing out of the induction pipe in the vicinity of the sealing portion. It is configured to be decomposed by acting on the layer and to be discharged through the connecting member .

By adopting the above configuration, it is possible to provide a connecting member for allowing gas to enter and exit only on one side, and the sealing structure between the cylindrical MEA and the connecting member may be provided in one place. Therefore, the reliability of connection is increased. In addition, the number of parts and processing steps can be reduced.

  In addition, by adopting the above configuration, the gas flowing through the cylindrical MEA can flow a distance twice as long as the cylindrical length of the cylindrical MEA. For this reason, after raising the temperature of gas in the said gas induction pipe, it can be made to act on the said cylindrical MEA. Therefore, it is possible to increase the gas decomposition efficiency, and it is possible to increase the gas throughput by increasing the gas flow rate.

  The structure which seals the one end part of the said cylindrical MEA is not specifically limited. For example, one end of the cylindrical MEA can be sealed with a bottom formed by integrally extending the solid electrolyte layer. Since the bottom part is integrally formed with the cylindrical MEA in the molding and sintering steps, there is no risk of gas leakage, and one end of the cylindrical MEA can be reliably sealed.

  Further, one end of the cylindrical MEA can be sealed by fitting a sealing member to the end of the cylindrical MEA. By adopting this configuration, the present invention can be applied to a conventional cylindrical MEA having both ends opened.

A connecting member having a double structure is provided at the gas inlet / outlet of the cylindrical MEA so that the gas before decomposition and the gas after decomposition do not mix. The connecting member is provided with a gas inlet communicating with the gas conducting pipe surrounds the outer periphery of the gas introduction pipe is configured with an exhaust annular space having a gas outlet on the side. By adopting the connection member, it is possible to introduce a gas containing a gas to be decomposed and discharge a gas containing the decomposed gas from one side of the cylindrical MEA.

  The gas induction pipe can be used as a current collector for the first electrode layer. That is, the gas induction pipe can be made of a conductive material and can be made to function as a current collector of the first electrode layer by being conducted to the first electrode layer.

  By using the gas induction pipe as a current collector for the first electrode layer, not only the gas decomposition efficiency can be increased, but also the space in the cylindrical MEA can be effectively utilized. In addition, a wiring conducting to the gas induction pipe can be provided in the protruding portion.

  Although the material which comprises the said gas induction pipe is not specifically limited, It is necessary to form with the material which corrosion etc. do not produce by the gas to decompose | disassemble. For example, it can be formed using a material made of a nickel alloy such as stainless steel, nickel, or Inconel (registered trademark of Special Metal Co.).

  The method for electrically connecting the first electrode layer and the gas induction pipe is not particularly limited. For example, a porous metal body having conductivity is inserted into a cylindrical flow path formed between the inner peripheral surface of the cylindrical MEA and the outer peripheral surface of the gas induction pipe, and the first electrode layer and the above The gas induction pipe can be conducted. Further, by providing the porous metal body, it is possible to secure a cylindrical flow path between the inner peripheral surface of the first electrode layer and the outer peripheral surface of the gas induction pipe, and the gas induction pipe. Can be positioned and held in the cylindrical MEA.

The materials constituting the first electrode layer and the second electrode layer are not particularly limited. For example , the first electrode layer and / or the second electrode layer may be a fired body including a metal particle chain body mainly composed of nickel (Ni) and an ion conductive ceramic. The metal particle chain refers to a bead-like elongated metal body formed by connecting metal particles. Ni, Fe-containing Ni, or Ni, Fe-containing Ni may be a metal containing a small amount of Ti. In a state where Ni or the like is oxidized, the surface of the metal particle chain is oxidized, and the contents (portion inside the surface layer) are not oxidized and retain the conductivity of the metal.

For this reason, for example, when the ion moving in the solid electrolyte layer is an anion (in some cases, it is a cation), the following effects are produced.
(A1) When a metal particle chain is contained in the first electrode layer (anode), in the first electrode layer (anode), the anion moving from the solid electrolyte layer and the first electrode layer ( The chemical reaction with the gas molecules in the gas led from the outside of the anode) to the first electrode layer (anode) is promoted by the oxidation layer of the metal particle chain (catalysis), and an anion is added. The chemical reaction in the first electrode layer (anode) is promoted (acceleration effect by electric charge). And as a result of the chemical reaction, the conductivity of the generated electrons can be ensured by the metal portion of the metal particle chain. As a result, the electrochemical reaction involving charge transfer in the first electrode layer (anode) can be accelerated as a whole. When the metal particle chain is contained in the first electrode layer (anode), a cation, for example, a proton is generated in the first electrode layer (anode), and the second electrode layer (cathode) is generated in the solid electrolyte layer. The cation can be moved to the surface, and the above-mentioned promoting action by the charge can be obtained similarly.
However, the oxide layer of the metal particle chain is surely formed by firing before use, but the oxide layer is often lost due to a reduction reaction during use. Even if the oxide layer disappears, the above-described catalytic action may or may not be reduced. In particular, Ni containing Fe or Ti has high catalytic action even without an oxide layer.
(A2) When the second electrode layer (cathode) contains a metal particle chain in the second electrode layer (cathode), the second electrode layer (cathode) from the outside of the second electrode layer (cathode). The chemical reaction of gas molecules in the gas led to gas) is promoted by the oxidation layer of the metal particle chain (catalysis), and the conductivity of the electrons from the external circuit is improved and the electrons are allowed to participate. The chemical reaction at the second electrode layer (cathode) is promoted (acceleration effect by electric charge). Then, anions can be efficiently generated from the molecules and delivered to the solid electrolyte layer. As in (A1), in the case of (A2), the electrochemical reaction between the cation that has moved through the solid electrolyte layer, the electrons that have flowed through the external circuit, and the second gas can be promoted. For this reason, the electrochemical reaction accompanied by transfer of electric charge in the second electrode layer (cathode) can be accelerated as a whole, as in the case of being included in the first electrode layer (anode). In what case, the metal particle chain is included in the second electrode layer (cathode) depending on the gas to be decomposed.
(A3) When the metal particle chain is contained in the first electrode layer (anode) and the second electrode layer (cathode), the effects (A1) and (A2) can be obtained.

  In many cases, the electrochemical reaction is limited by the moving speed or moving time of the solid electrolyte layer of ions. In order to increase the moving speed of ions, the gas decomposing apparatus generally includes a heating device that can accommodate the entire cylindrical MEA, such as a heater, and is usually set to a high temperature, for example, 600 ° C to 1000 ° C. By raising the temperature, not only the ion transfer speed but also a chemical reaction accompanied by charge transfer in the electrode layer is promoted.

  When the ions moving through the solid electrolyte layer are anions, they are generated and supplied by a chemical reaction at the second electrode layer (cathode) as described above. Molecules in the fluid and electrons introduced in the second electrode layer (cathode) react to generate anions. The generated anion moves in the solid electrolyte layer to the first electrode layer (anode). The electrons participating in the reaction at the second electrode layer (cathode) include an external circuit (capacitor, power source, and power consuming device) that connects the first electrode layer (anode) and the second electrode layer (cathode). ) Comes in. When the ions moving through the solid electrolyte layer are cations, they are generated by an electrochemical reaction in the first electrode layer (anode) and move through the solid electrolyte layer to the second electrode layer (cathode). Electrons are generated at the first electrode layer (anode) and flow through an external circuit to the second electrode layer (cathode) to participate in the electrochemical reaction at the second electrode layer (cathode). The electrochemical reaction may be a power generation reaction as a fuel cell, or may be an electrolysis reaction.

The solid body electrolyte layer can have a structure having oxygen ion conductivity or proton conductivity. When an oxygen ion conductive solid electrolyte is used, for example, electrons and oxygen molecules are reacted in the second electrode layer (cathode) to generate oxygen ions, which are then moved in the solid electrolyte layer. A predetermined electrochemical reaction can be caused in one electrode layer (anode). In this case, since the moving speed of oxygen ions in the solid electrolyte layer is not large compared to protons, the temperature is sufficiently increased and / or the thickness of the solid electrolyte layer is sufficiently thin to obtain a practical level of decomposition capacity. Such measures are necessary.

On the other hand, barium zirconate (BaZrO ₃ ) is known as a proton conductive solid electrolyte. When a proton conductive solid electrolyte is used, for example, ammonia is decomposed at the first electrode layer (anode) to generate protons, nitrogen molecules and electrons, and this proton is passed through the solid electrolyte layer to the second electrode layer. It moves to (cathode) and reacts with oxygen in the second electrode layer (cathode) to generate water (H ₂ O). Since protons are small compared to oxygen ions, the moving speed in the solid electrolyte layer is high, and a practical decomposition capacity can be obtained by lowering the heating temperature.

  For example, when ammonia decomposition is performed using a cylindrical MEA, the oxygen ion conductive solid electrolyte layer is a reaction that generates water in the first electrode layer (anode) of the cylindrical MEA. Water forms water droplets near the outlet where the temperature is low, causing pressure loss. In contrast, when a proton conductive solid electrolyte layer is used, protons, oxygen molecules, and electrons are generated at the second electrode layer (cathode) (outside). Since the outside is almost open, even if it adheres as water droplets, pressure loss is unlikely to occur.

Further, the decomposition target gas as fuel, it is also possible to configure the power generating device comprises a gas decomposition apparatus.

  It is possible to provide a gas decomposition apparatus that can prevent external piping, a connecting member that connects the external piping, and a seal structure provided between them from being damaged by heat, and can further reduce manufacturing costs.

It is a longitudinal cross-sectional view which shows schematic structure of the gas decomposition apparatus of this invention. It is a longitudinal cross-sectional view which shows the front end side (sealing side) of the gas decomposition apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which follows the III-III line in FIG. It is a figure which shows the electrical wiring system | strain in the gas decomposition apparatus of FIG. It is a longitudinal cross-sectional view by the side of the protrusion part (opening end side) of the gas decomposition apparatus shown in FIG. It is an expanded longitudinal cross-sectional view of the principal part of the gas decomposition apparatus which concerns on 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a schematic configuration of a gas decomposition apparatus 100 according to a first embodiment of the present invention. In the present embodiment, a gas decomposition apparatus 100 in which the first gas used for decomposition is an ammonia-containing gas and air is used as the second gas will be described.

  In the first embodiment, a gas decomposition apparatus 100 is configured by housing a plurality of gas decomposition elements 10 each including a cylindrical MEA 7 in a heating container 51.

  The cylindrical MEA 7 is provided with a projecting portion 41 by accommodating the upper portion in the heating container 51 and projecting the lower portion downward from the heating container. A connecting member 30 is provided at the opening end of the lower end of the cylindrical MEA 7, and a first gas channel 91 is formed through the connecting member 30 to the first gas channel 91 formed inside the cylindrical MEA. The gas is introduced and discharged.

  The heating vessel 51 is provided with a heater 52, and the heater 52 is operated to heat the cylindrical MEA 7 and the first and second gases applied to the cylindrical MEA 7. doing. The heater 52 is configured to be controlled by a control device (not shown), and a predetermined temperature is maintained, for example, at 800 to 1000 ° C. in the heating container 51.

  In the lower part of the heating container 51, an inlet 61 for introducing the second gas is provided, and an outlet 62 for discharging the processed second gas is provided in the upper part. The space S in the heating container 51 is configured to flow from below to above.

  FIG. 2 is an enlarged longitudinal sectional view of a main part showing the structure inside the heating vessel 51 in the gas decomposition apparatus 100. 3 is a cross-sectional view taken along line III-III in FIG.

The gas decomposition element 10 is provided with a first electrode layer (anode) 2 so as to cover the inner surface of the cylindrical solid electrolyte layer 1, and a second electrode layer (cathode) 5 so as to cover the outer surface. The cylindrical MEA 7 (1, 2, 5) is provided. The first electrode layer (anode) 2 may be called a fuel electrode, and the second electrode layer (cathode) 5 may be called an air electrode.
In the present embodiment, as described above, the ammonia-containing gas flows as the first gas inside the cylindrical MEA 7 (1, 2, 5). On the other hand, in the heating container 51 outside the cylindrical MEA 7 (1, 2, 5), air that is an oxygen-containing gas flows as the second gas.

  By providing the connecting member 30 by projecting the protruding portion 41 below the heating container 51, heat conducted from the heating container 51 to the connecting member 30 can be reduced. In addition, since the protrusion 41 protrudes downward from the heating container 51, the connection member 30 and the protrusion 41 are not exposed to high-temperature air that convects around the heating container 51. For this reason, the temperature on the lower end side (connecting member 30 side) of the protruding portion 41 is lowered, and a high temperature does not act on the connecting member 30. Moreover, the fall of the sealing performance between cylindrical MEA7 and the said connection member 30 can be prevented. Thereby, high heat resistance is not required for the connecting member 30 and the gas introduction pipe 45 connected thereto, and the connection reliability is increased and the manufacturing cost can be reduced.

  In addition, in the present embodiment, a cooling means 70 that can cool the connection member 30 and a part of the protrusion 41 (near the lower end) is provided. The cooling means 70 includes a cooling chamber 71 that flows the second gas (air) before flowing into the heating container 51 so as to surround a part of the connection member 30 and the protruding portion 41. Yes. The cooling chamber 71 is provided with an intake 72 for taking the second gas into the cooling chamber 71 at a location away from the heating container 51, and air at an outside temperature serves as the second gas. Incorporated. A pipe 73 connected to the inlet 61 of the heating container 51 is provided on the opposite side of the cooling chamber 71 from the inlet 72.

  The second gas introduced from the intake 72 is configured to flow into the heating container 51 through the pipe 73 while flowing around the connection member 30 and a part of the protrusion. ing.

  The second gas is caused to flow in the cooling chamber 71 and the heating container 51 by a fan or a suction device (not shown). Therefore, it is possible to prevent high heat from acting on the connecting member 30, the protruding portion 41, and the seal structure provided between them only by providing the cooling chamber 71.

  By employ | adopting the said structure, it becomes possible to form the said connection member 30 from a resin material. The kind of the resin material is not particularly limited. For example, it is preferable to employ a fluororesin having high heat resistance. By forming the connecting member from a resin material, it becomes possible to easily perform processing and the like, and the manufacturing cost can be reduced.

  In the present embodiment, the protruding length of the protruding portion 41 is set so that the temperature of the connecting member 30 is lower than the heat resistant temperature of the fluororesin, for example, 260 ° C. or lower, and the cooling means 70 is provided. .

  The cooling means is not limited to the one provided with the cooling chamber. For example, the protrusion 41 can be provided with a fan or the like that sends cooling air directly. In addition, a cooling conduit through which cooling water flows may be provided around the protrusion 41. By providing the cooling means 70, the cooling efficiency of the projecting portion 41 and the connecting member 30 is increased, and the projecting length of the projecting portion 41 can be shortened. Therefore, the gas decomposition apparatus 100 can be reduced in size.

  In the gas decomposition element 10 of the present embodiment, one end (upper end) side of the cylindrical MEA 7 (1, 2, 5) is sealed, and stainless steel, copper, nickel, A gas induction pipe 11k made of an alloy containing iron, chromium, niobium, molybdenum or the like based on Ni, such as Inconel, that is, a material having heat resistance to 600 to 1000 ° C. and ammonia gas corrosion resistance is provided. Has been inserted. The one end portion is provided with a sealing portion 44 by extending the solid electrolyte layer 1 and the inner electrode layer 2 of the cylindrical MEA 7 (1, 2, 5) and providing a bottom portion.

  The gas induction pipe 11k is inserted from the other end portion side of the cylindrical MEA 7 (1, 2, 5) toward the sealing portion 44 side which is the one end portion. A cylindrical flow path 43 is set between the inner peripheral surface of the electrode layer 2 and the outer peripheral surface of the gas induction pipe 11k. A porous metal body 11s is inserted into the cylindrical flow path 43, and the gas guide pipe 11k is held at the center while the outer peripheral surface of the gas guide pipe 11k and the first electrode layer 2 are in contact with each other. A cylindrical flow path 43 is formed between the inner peripheral surface.

  In the gas decomposition element 10 according to the present embodiment, the first gas is caused to flow toward the sealing portion 44 in the internal space 42 of the gas guiding pipe 11k, and the gas guiding pipe is disposed in the vicinity of the sealing portion 44. The first gas is allowed to flow out from the inside of 11k and reversed, and the first gas is caused to flow in the direction opposite to the flow in the internal space 42 through the cylindrical flow path 43. That is, the first gas flow path 91 is configured by the internal space 42 and the cylindrical flow path 43.

  By adopting the above-described configuration, the gas can be used as the first gas flow path in the space inside the cylindrical MEA 7 at a distance approximately twice the cylinder length of the cylindrical MEA 7. For this reason, it is heated in the gas induction pipe 11k and acts on the cylindrical MEA 7 in a state where the temperature is raised. Therefore, the decomposition efficiency of the first gas can be increased, and the gas flow rate can be increased to increase the gas throughput.

  The gas induction pipe 11k is made of a conductive metal such as stainless steel, and is configured to function as a component of the anode current collector 11. On the other hand, the cathode current collector 12 is arranged so as to wrap around the outer surface of the second electrode layer (cathode) 5.

  The anode side current collector 11 includes a silver paste coating layer 11g, a Ni mesh sheet 11a, a porous metal body 11s, and the gas induction pipe 11k. The Ni mesh sheet 11a is in contact with the first electrode layer (anode) 2 on the inner surface side of the cylindrical MEA 7 through the silver paste coating layer 11g, and conducts from the porous metal body 11s to the gas induction pipe 11k. Is configured to do. The tip portion W1 of the Ni mesh sheet 11a is conductively connected in the vicinity of the sealing portion 44 so as to be wound around the outer peripheral portion of the gas induction pipe 11k via a band-shaped joining member W2. Therefore, the Ni mesh sheet 11a includes, in parallel, a conductive path of (1) Ni mesh sheet 11a / porous metal body 11s / gas induction pipe 11k, and (2) Ni mesh sheet 11a / gas induction pipe 11k, The conductive path is formed. As a result, it is possible to prevent an increase in pressure loss while being located on the inner surface of the cylindrical MEA 7 and maintaining a low electrical resistance.

  As the porous metal body 11s, in order to reduce the pressure loss of the first gas, it is preferable to use a metal plated body that can increase the porosity, such as Celmet (registered trademark: Sumitomo Electric Industries, Ltd.). In order to reduce the electrical resistance between the first electrode layer (anode) 2 and the anode-side current collector 11, the silver paste coating layer 11g and the Ni mesh sheet 11a are disposed.

  The cathode current collector 12 includes a silver paste coated wiring 12g and a Ni mesh sheet 12a. In the present embodiment, the Ni mesh sheet 12a contacts the outer surface of the cylindrical MEA 7 and conducts to the external wiring 12e. The silver paste coated wiring 12g contains silver that acts as a catalyst for promoting the decomposition of oxygen in the oxygen-containing gas (air), which is the second gas, into oxygen ions in the second electrode layer (cathode) 5. In addition, this contributes to lowering the electrical resistance of the cathode current collector 12. The silver paste coated wiring 12g has a catalytic action equivalent to that of the silver particles contained in the second electrode layer (cathode) 5 by contacting the silver particles with the second electrode layer (cathode) 5 while passing oxygen molecules. To express.

In the present embodiment, a preheating pipe 53 is arranged in the space S in the heating container 51 so as to penetrate the heating container 51. The preheating pipe 53 is a pipe for preheating the first gas. By passing the first gas through the preheating pipe 53 before being introduced into the cylindrical MEA 7, the first gas having a low temperature is suddenly introduced into the cylindrical MEA 7, resulting in insufficient reaction. Is solved. As a result, it is possible to improve the decomposition performance and make the gas decomposition element 10 compact. The preheating pipe 53 includes a connection end 53a connected to the pipe from the first gas source, and the downstream side is connected to the gas introduction pipe 45.
As the preheating pipe 53, a heat-resistant pipe such as a Ni pipe, an Inconel pipe, or other metal or ceramic pipe having heat resistance and corrosion resistance can be used.

Although the said heating container 51 is comprised with a heat-resistant material, it is good also as what is comprised thickly with the refractory material and embedded the heater 52. FIG. Moreover, it can also be set as the structure which embed | buried and penetrated the preheating piping 53 in the thickness of the heating container 51 which consists of a thick refractory material.
By heating the preheating pipe 53 using the heater 52 for heating the cylindrical MEA 7, the first gas can be efficiently preheated.

FIG. 4 is a diagram showing an electrical wiring system of the gas decomposition element 10 of FIG. 1 when the solid electrolyte layer 1 is oxygen ion conductive. The first gas containing ammonia passes through the preheating pipe 53, and then passes through the gas induction pipe 11k to the innermost part of the inner cylinder of the cylindrical MEA 7 with strict airtightness, that is, the sealing part. It is guided to the vicinity of 44. The cylindrical MEA 7 is entirely heated to about 800 ° C. by the heater 52, and the temperature of the first gas is raised while flowing in the gas induction pipe 11k. During this time, ammonia in the first gas is decomposed as 2NH ₃ → N ₂ + 3H ₂ by heating in the gas induction pipe 11k.

  When the cylindrical MEA 7 is used, the porous metal body 11s is used to pass the first gas containing the decomposition gas on the inner surface side and hold the gas induction pipe 11k. From the viewpoint of reducing the pressure loss, as described above, a porous metal plated body, for example, the above-mentioned Celmet (registered trademark) can be used as the porous metal body 11s disposed in the cylindrical flow path 43. . The first gas containing ammonia flows through the first gas flow path from the internal space 42 into the cylindrical flow path 43, and the porous metal body 11s, the Ni mesh sheet 11a, and the porous silver paste coating layer The following ammonia decomposition reaction is performed in contact with the first electrode layer (anode) 2 while passing through the 11 g gap.

Oxygen ions O ²⁻ are generated by an oxygen gas decomposition reaction in the second electrode layer (cathode) 5 and reach the first electrode layer (anode) 2 through the solid electrolyte layer 1. That is, it is an electrochemical reaction when oxygen ions, which are anions, move through the solid electrolyte layer 1.

In the first electrode layer (anode) 2, the following reaction occurs.
(Anode reaction): 2NH ₃ + 3O ²⁻ → N ₂ + 3H ₂ O + 6e ⁻
More specifically, a part of ammonia causes a reaction of 2NH ₃ → N ₂ + 3H ₂ , and this 3H ₂ reacts with oxygen ions 3O ²⁻ to generate 3H ₂ O.
Air, particularly oxygen gas, is introduced into the second electrode layer (cathode) 5 so as to pass through the space S, and oxygen ions decomposed from oxygen molecules in the second electrode layer (cathode) 5 are converted into the first electrode layer. (Anode) 2 is sent to the solid electrolyte layer 1.

In the second electrode layer (cathode) 5, the following reaction occurs.
(Cathode reaction): O ₂ + 4e ⁻ → 2O ²⁻
As a result of the above electrochemical reaction, electric power is generated, and a potential difference is generated between the first electrode layer (anode) 2 and the second electrode layer (cathode) 5, and the anode side current collector 12 performs the anode side current collection. A current I flows to the electric body 11. If a load, for example, a heater 52 for heating the gas decomposition element 10 is connected between the cathode-side current collector 12 and the anode-side current collector 11, electric power for that purpose can be supplied. The supply of the electric power to the heater 52 may be partial. In many cases, the supply amount of private power generation is less than half of the electric power required for the entire heater 52.

  In the gas decomposition element 10, in the first electrode layer (anode) 2 on the inner surface side of the cylindrical MEA 7, the pressure loss of the first gas passing through the anode-side current collector 11 is lowered while the electrical resistance of the anode-side current collector 11 is lowered. Is important. Further, on the second electrode layer (cathode) 5 side, the contact portion between the second gas, air, and the second electrode layer (cathode) 5 is densified to reduce the resistance of the cathode current collector 12. It is important to keep it low.

The above is an electrochemical reaction in which oxygen ions, which are anions, move through the solid electrolyte layer 1. For example, barium zirconate (BaZrO ₃ ) is used for the solid electrolyte layer 1 to generate protons in the first electrode layer (anode). The reaction that is generated in step 2 and moves in the solid electrolyte layer 1 to the second electrode layer (cathode) 5 is also a desirable embodiment of the present invention.

When proton conductive solid electrolyte layer 1 is used, for example, when ammonia in the first gas is decomposed, ammonia is decomposed at first electrode layer (anode) 2 to generate protons, nitrogen molecules, and electrons. Then, protons are transferred to the second electrode layer (cathode) 5 through the solid electrolyte layer 1 and reacted with oxygen in the second electrode layer (cathode) 5 to generate water (H ₂ O). Since protons are smaller than oxygen ions, the moving speed in the solid electrolyte layer 1 is large. For this reason, a practical decomposition capacity can be obtained while lowering the heating temperature. The thickness of the solid electrolyte layer 1 can also be set to a thickness that can ensure strength.

  FIG. 5 is a longitudinal sectional view showing the structure in the vicinity of the lower end portion of the gas decomposing element 10. The connection member 30, the connection structure of the connection member 30 and the gas induction pipe 11 k, and the connection structure of the connection member 30 and the cylindrical MEA 7. The structure of the cooling means 70 is shown.

  In the present embodiment, the cylindrical MEA 7 is accommodated in the heating container 51, and a protruding portion 41 is provided by projecting a part of the cylindrical MEA 7 below the heating container 51. A connecting member 30 for allowing the first gas to enter and exit is provided in the part.

  In the connection member 30, the O-ring 33 housed on the inner surface side of the fastening portion 31 b extending from the main body portion 31 to the solid electrolyte layer 1 is in contact with the outer surface of the ceramic solid electrolyte layer 1 that is a fired body. Connected with. The fastening portion 31b of the connection member 30 has an outer diameter that is tapered, and a screw is cut there, and an annular screw 32 is screwed into the screw. By screwing in the direction in which the outer diameter of the annular screw 32 is increased, the fastening portion 31b is fastened from the outer surface, and the airtightness by the O-ring 33 can be adjusted. By forming the protrusion 41, the temperature acting on the O-ring 33 can be lowered, the life of the O-ring 33 can be extended, and the reliability of the seal structure can be increased.

  Inside the connection member 30, a fitting portion 36 is formed in which the base end portion 11 d of the gas guiding pipe 11 k can be fitted with airtightness. As a result, the gas guiding pipe 11k and the connecting member 30 are connected to form a first gas passage.

  The connection member 30 is provided with a gas introduction part 31a for connection with the gas introduction pipe 45 for the first gas. By fitting the end portion of the gas introduction pipe 45 to the outer periphery of the gas introduction portion 31 a of the connection member 30 and fastening with the fastener 47, a good airtight connection can be obtained. The first gas flows from the gas introduction pipe 45 through the gas introduction part 31a into the gas induction pipe 11k. The first gas that has flowed into the gas induction pipe 11k flows through the internal space 42 to the vicinity of the sealing portion 44 of the cylindrical MEA 7.

  Further, the connection member 30 is provided with a gas discharge part 31 c for connecting to the exhaust pipe 65. By fitting the end portion of the gas exhaust pipe 65 to the outer periphery of the gas discharge portion 31 c of the connection member 30 and fastening with the fastener 67, a connection with good airtightness can be obtained. The first gas that has passed through the cylindrical MEA 7 is discharged to the exhaust pipe 65 through the exhaust space 35 and the gas discharge portion 31 c in the connection member 30.

  By adopting the connection member 30, the first gas is allowed to enter and exit from the same one side position of the cylindrical MEA 7 without mixing the first gas before decomposition and the first gas after decomposition. It becomes possible.

  The main body portion 31 of the connection member 30 is provided with a conductive through portion 37c that penetrates the main body portion 31 while maintaining airtightness, and is coated with a sealing resin 38 or the like in order to maintain airtightness. The conductive penetrating portion 37c is a cylindrical rod, and a screw for screwing the nut 39 is preferably cut in order to make a reliable conductive connection with the external wiring 11e. A conductive wire 37b is joined to the distal end of the conductive through portion 37c in the tube, and the other end 37a of the conductive wire 37b is joined to the outer peripheral portion of the gas induction pipe 11k via an annular fastening tool 34. .

  By adopting the above configuration, the connection resistance between the gas induction pipe 11k and the external wiring 11e can be reduced.

  On the other hand, external wiring 12e can be circulated around the outer periphery of the end portion of the Ni mesh sheet 12a of the cathode-side current collector 12, thereby leading to the outside.

  As shown in FIG. 5, the connection between the anode-side current collector 11 and the external wiring 11e and the connection between the connection member 30, the gas introduction pipe 45, and the gas exhaust pipe 65 can be performed in a small space. In addition, the above connection is made on the distal end side of the protruding portion 41. That is, it is performed at a position deviating from the main flow portion of the heat flow from the heater 52. For this reason, even if the connection member 30 is formed of a heat-resistant resin such as a fluororesin, it is possible to ensure long-term repeated durability.

  The cooling chamber 71 is provided so as to include the entire connection member 30 and a part of the protrusion 41. The gas introduction part 31 a and the exhaust pipe 65 extend through the wall of the cooling chamber 71 to the outside of the cooling chamber 71, and include a first ammonia containing ammonia via the gas introduction pipe 45. Is introduced into the cylindrical MEA 7 and the first gas from which ammonia has been removed is discharged from the exhaust pipe 65.

  As the powder material constituting the solid electrolyte layer 1, a solid oxide, molten carbonate, phosphoric acid, solid polymer, or the like can be used. Solid oxides are preferred because they can be miniaturized and are easy to handle. Examples of the solid oxide include oxygen ion conductive SSZ (scandium stabilized zirconia), YSZ (yttrium stabilized zirconia), SDC (samarium stabilized ceria), LSGM (lanthanum gallate), GDC (gadria stabilized ceria), and the like. Should be used. Proton conductive barium zirconate can also be used. Each said powder material can be baked by hold | maintaining at 1000 degreeC-1600 degreeC for about 30 minutes-180 minutes by air | atmosphere atmosphere.

  The first electrode layer (anode) 2 can be formed as a fired body mainly composed of a metal particle chain having an oxidized layer that is surface oxidized and an oxygen ion conductive ceramic. As oxygen ion conductive ceramics, SSZ (scandium stabilized zirconia), YSZ (yttrium stabilized zirconia), SDC (samarium stabilized ceria), LSGM (lanthanum gallate), GDC (gadria stabilized ceria), etc. should be used. Can do.

  When adopting the above SSZ, it is preferable to use one having an average diameter of about 0.5 μm to 50 μm. The firing step can be performed by holding at 1000 ° C. to 1600 ° C. for about 30 minutes to 180 minutes in an air atmosphere. The average diameter of the raw material powder of SSZ is preferably about 0.5 μm to 50 μm. The compounding ratio of the surface-oxidized metal particle chain and SSZ is in the range of 0.1 to 10 in terms of molar ratio.

  The metal of the metal particle chain is preferably nickel (Ni) or one containing Ni (Fe) in Ni. More preferably, it contains a very small amount of titanium (Ti) of about 2 to 10000 ppm.

  The metal particle chain is preferably produced by a reduction precipitation method. The reduction precipitation method for this metal particle chain is described in detail in JP-A No. 2004-332047. The average diameter D of the metal particle chain contained in the first electrode layer (anode) 2 is preferably in the range of 5 nm to 500 nm. The average length L is preferably in the range of 0.5 μm or more and 1000 μm or less. The ratio between the average length L and the average diameter D is preferably 3 or more. However, it may have dimensions outside these ranges.

  The second electrode layer (cathode) 5 is formed from a fired body mainly composed of oxygen ion conductive ceramics. As the oxygen ion conductive ceramic in this case, LSM (lanthanum strontium manganite), LSC (lanthanum strontium cobaltite), SSC (samarium strontium cobaltite), or the like can be used. These powder materials can also be fired under the same conditions as described above.

  FIG. 6 shows a second embodiment of the present invention. The second embodiment is configured by providing a protruding member 241 corresponding to the protruding portion 41 according to the first embodiment. Note that the configurations of the cylindrical MEA 207, the heating container 251 and the like are the same as those in the first embodiment, and thus description thereof is omitted.

  As shown in FIG. 6, in 2nd Embodiment, the flange part 251a which can fix the said cylindrical MEA207 is provided in the bottom part of the heating container 251 by which the said cylindrical MEA207 is penetrated. The cylindrical MEA 207 is fixed to the flange portion 251a in a state in which a part thereof extends to the outside of the heating container 251. The inner peripheral portion of the flange portion 251a is filled with a heat-resistant sealing material, and airtightness between the outer peripheral portion of the cylindrical MEA 207 and the inner peripheral portion of the flange portion 251a is ensured.

  A cylindrical projecting member 241 extending in the axial direction of the cylindrical MEA 207 is provided on the outer surface side of the wall portion provided with the flange portion 251a. The projecting member 241 accommodates the extending portion 207b of the cylindrical MEA 207 with airtightness, and a fluororesin connecting member 230 is connected to the distal end side.

  A flange portion 241 a is formed on the heating container side of the protruding member 241, and is fixed to the wall portion of the heating container by screw means 261. A heat-resistant gasket (not shown) is interposed between the flange portion 241a and the outer surface of the heating container 251 so that airtightness between the protruding member 241 and the heating container 251 is ensured, and a tubular shape. The gas flowing in the MEA is configured not to leak.

  On the other hand, the front end portion 241b of the protruding member 241 is fitted with a fitting portion 236 provided on the connecting member 230 with airtightness.

  The protruding member 241 can be formed using various materials as long as the temperature acting on the connecting member 230 can be reduced. For example, the connecting member can be formed from a heat-resistant and heat-insulating material such as ceramic. Further, by forming from a metal material such as nickel having high heat dissipation, the heat conducted from the cylindrical MEA 207 is dissipated in the protruding member 241 so that the temperature acting on the connecting member 230 is reduced. It can also be configured.

  Similarly to the first embodiment, the protruding member 241 is provided with a conductive through portion (not shown) that penetrates while maintaining airtightness, and extends from the outer peripheral portion of the gas induction pipe 211k constituting the first current collector. The connection wiring 211e extends to the outside of the protruding member 241. Further, the connection wiring 212e extending from the second current collector provided on the outer peripheral portion of the cylindrical MEA 207 is also extended from the protruding member 241 as described above.

  By adopting the above configuration, the temperature acting on the connection member 230, the connection wirings 211e, 212e, and the like can be greatly reduced. In addition, since almost the entire cylindrical MEA 207 can be accommodated in the heating container 251, it is possible to increase the gas decomposition efficiency by applying a uniform temperature to the cylindrical MEA.

  Furthermore, by employing the protruding member 241, the cooling means 271 can be easily provided. For example, as shown in FIG. 6, it is possible to integrally form the radiation fins 271a on the protruding member 241. Moreover, piping which employ | adopts cooling air or cooling water can also be provided integrally. Therefore, by employing the protruding member 241, the temperature acting on the connecting member 230 can be significantly reduced.

  In the above-described embodiments, the present invention is applied to a gas decomposition apparatus for the purpose of gas abatement. However, the present invention can be applied to a gas decomposition apparatus not intended for a gas abatement and a cylindrical MEA of an electrochemical reaction apparatus. For example, it can also be used for a cylindrical MEA that constitutes a power generator such as a fuel cell.

  The embodiments of the present invention disclosed above are merely examples, and the scope of the present invention is not limited to these embodiments. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  Not only is the gas decomposition performance high, but a high temperature does not act on the connecting member and the external piping, and a highly reliable gas decomposition apparatus and power generation apparatus can be provided.

DESCRIPTION OF SYMBOLS 1 Solid electrolyte layer 2 1st electrode layer (anode)
5 Second electrode layer (cathode)
7 Tubular MEA
DESCRIPTION OF SYMBOLS 10 Gas decomposition | disassembly element 11 Anode side collector 11k Gas induction pipe 11s Porous metal body 12 Cathode side collector 12e External wiring 30 Connection member 41 Protrusion part 42 Internal space 43 Cylindrical flow path 44 Sealing part 45 Gas introduction pipe 51 Heating vessel 52 Heating heater 53 Preheating pipe 65 Exhaust pipe 100 Gas decomposition device S Space W1 Tip of Ni mesh sheet W2 Joining member

Claims (9)

A cylindrical shape having a cylindrical solid electrolyte layer, a first electrode layer stacked on the inner periphery of the solid electrolyte layer, and a second electrode layer stacked on the outer periphery of the solid electrolyte layer A gas decomposition apparatus configured using MEA (Membrane Electrode Assembly),
A connection member for allowing the first gas to enter and exit the cylindrical MEA;
A heating container that accommodates and heats the cylindrical MEA and causes the second gas to flow ;
A sealing portion disposed in the heating container, the sealing member being disposed at one end of the cylindrical MEA;
A gas induction pipe that is inserted into the inner space of the cylindrical MEA and forms a cylindrical flow path between the inner peripheral surface of the cylindrical MEA;
Cooling means for cooling the connection member and / or the protrusion,
The connection member includes a gas introduction portion communicating with the gas induction pipe, and includes an annular exhaust space that surrounds an outer peripheral portion of the gas induction pipe and includes a gas discharge portion on a side portion.
The gas introduced into the gas induction pipe via the connection member is caused to flow toward the sealing portion, and is reversely flowed by flowing out of the induction pipe in the vicinity of the sealing portion, whereby the cylinder A gas decomposing apparatus configured to act on the first electrode layer while causing the flow path to flow in a direction opposite to the flow in the gas induction pipe and to be decomposed and discharged via the connecting member . 2. The gas decomposition apparatus according to claim 1 , wherein the cooling unit is configured to cool the connection member and / or the protrusion using the second gas before flowing into the heating container. 3. The gas decomposition apparatus according to claim 1 , wherein the projecting portion is configured by projecting a part of the cylindrical MEA from the heating container. The gas decomposition apparatus according to claim 1 or 2 , wherein a part or all of the protruding portion is formed of a member separate from the cylindrical MEA. The gas decomposition apparatus according to any one of claims 1 to 4 , wherein a temperature at a tip of the protrusion is set to 260 ° C or lower. The gas decomposition apparatus according to any one of claims 1 to 5 , wherein the connection member is formed of a resin material. The first electrode layer and / or the second electrode layer is a fired body including a metal particle chain composed mainly of nickel (Ni) and an ion conductive ceramic. The gas decomposition apparatus according to any one of claims 1 to 6 . The gas decomposition apparatus according to any one of claims 1 to 7 , wherein the solid electrolyte layer has oxygen ion conductivity or proton conductivity. A power generator comprising the gas decomposition apparatus according to any one of claims 1 to 8 .

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