JP5052928B2 - Solid oxide fuel cell - Google Patents

Description

  The present invention relates to a solid oxide fuel cell.

  Solid oxide fuel cells, which are a type of fuel cell operated at high temperatures, are used in a structure in which a plurality of cells, which are basic units constituting the battery, are combined and integrated, and a plurality of cells are arranged and stored in a cell container. The

  A combination of a plurality of cell tubes combined together is called a bundle. A plurality of the bundles are stored in a cell container, raised to a predetermined operating temperature, a battery reaction gas made of an anode gas or a cathode gas is allowed to flow into the container, and a battery reaction gas flowing into the container inside the cell tube and Generates a power generation reaction by flowing a counter electrode gas.

  The cell tube has electrodes formed inside and outside, and a barrier between them is an electrolyte. For cell tubes, the inner electrode is the fuel electrode (anode) and the outer electrode is the air electrode (cathode), while the inner electrode is the air electrode and the outer electrode is the fuel electrode. There is.

  The bundle is usually arranged so that a current flows in one direction in the cell container, and it is necessary to ensure electrical conductivity so that a current flows between the bundles.

  The constituent material of the cell tube and the bundle is mainly composed of ceramics, and has a smaller thermal expansion coefficient than the metal material. On the other hand, a metal material is used for the container for storing the bundle in consideration of strength and cost. For this reason, at a high battery operating temperature, a gap is formed between the bundle and the container, the contact between the bundles may be separated, and current may not flow.

When a gap is generated between the bundle and between the bundle and the container, the battery reaction gas flows through the gap and passes through without contributing to the battery reaction. For this reason, it will be in the state which cannot give the amount of gas required for battery reaction to a cell, and will cause the fall of battery performance and the fall of power generation efficiency. The gas flow that passes without contributing to the battery reaction is referred to as bypass flow, and it is possible to prevent gaps between the bundles and between the bundles and between the bundles. In order to ensure the electrical conductivity of the bundle, it is known to apply a pressing pressure to the bundle from the outside (see, for example, Patent Document 1).

JP 2006-107813 A (summary)

  Patent Document 1 describes that a clamping force is applied to the container side wall by a pushing mechanism such as a clamping spring. In this method, a pressing pressure is generated between the bundles and between the bundles and the containers with respect to the pressing portion, and electrical conductivity can be ensured and bypass flow can be prevented. However, at the position away from the pressing portion, the pressing pressure is small or not at all, and it is difficult to ensure electrical conductivity and prevent bypass flow.

  Further, in the pushing mechanism using the clamping spring, the container side wall is distorted like a wave, so there is a possibility that a gap is generated between the points pressed against each other. This problem can be improved to some extent by increasing the number of points to be tightened, but there is a limit and the structure becomes too complex.

  An object of the present invention is to provide a solid oxide fuel cell in which a gap is generated between the bundles and between the bundle and the container, and the occurrence of a bypass flow is suppressed.

  The present invention relates to a solid oxide fuel cell in which a plurality of solid oxide fuel cells are combined and integrated to form a bundle, a plurality of bundles are arranged and stored in a cell container, and a battery reaction gas is allowed to flow around the cell. In the fuel cell, the cell container has a double structure including an inner wall and an outer wall, and a compressible material having compressibility is compressed between the inner wall and the outer wall even at a high battery operating temperature. It is arranged.

  In addition, the cell container has a double structure consisting of an inner wall and an outer wall, and a compressible material having compressibility is disposed between them at a high battery operating temperature, and between the inner wall and the bundle. A similar compressible material is disposed in a compressed state between them.

  According to the present invention, the compressed material, which is arranged between the inner wall and the outer wall, and between the inner wall and the bundle, which is compressible even at a high battery operating temperature, uniformly pushes the bundle. Since pressure can be applied, bypass flow can be prevented. Moreover, since the pressing force by the compressed material is applied to the entire inner side wall and outer side wall, the container side wall can be prevented from being distorted.

  In the present invention, the inner wall material of the cell container is made of a material having a coefficient of thermal expansion equivalent to or substantially the same as that of the cell, and the generation of a gap between the bundle and the container due to the difference in the coefficient of thermal expansion is suppressed. Is desirable. The coefficient of thermal expansion of the inner wall material is preferably within ± 10% of the coefficient of thermal expansion of the cell.

  In the present invention, the compressed material disposed between the outer wall and the inner wall of the cell container applies a pressing force to the inner wall and the bundle, and the gap is less likely to occur. It is possible to use a material having a higher coefficient of thermal expansion than the cell. If the same material as the constituent material of the gas header and exhaust gas combustion chamber disposed around the cell is used as the outer wall material, it can be integrated by a welding structure or the like, and the manufacture becomes easy. Further, gas leakage from the inside to the outside can be prevented.

  Hereinafter, an embodiment of the present invention will be described taking an example of a cylindrical cell tube, in which the inside of the tube is a cathode, the outside is an anode, and the barrier therebetween is an electrolyte. However, the present invention is not limited to the following examples.

FIG. 1 shows a solid oxide fuel cell according to the present invention, where (a) is a plan view and (b) is an elevational view. The cell tube 1 is a cylindrical cell, and a bundle 2 is obtained by integrating 2 cells × 6 series = 12 cells. A current collecting plate 3 is disposed between the bundles, and a predetermined pressing force is applied to the current collecting plates 3 to ensure electrical conductivity. An inner seal skin 9 is disposed around these as an inner wall. The inner seal skin 9 is configured to cover the entire side surface of the bundle. And the high temperature compression material 8 is arrange | positioned between the inner side seal skin 9 and a bundle. The high temperature compression material 8 is disposed in a direction in which the bundle 2 and the current collector plate 3 are in contact with each other. The high-temperature compression material 8 is disposed in a compressed state by a necessary amount so that a sufficient pressing force is applied to ensure electrical conductivity between the bundle 2 and the current collector plate 3.

  Further, an outer seal skin 10 is arranged as an outer wall around the inner seal skin 9. Then, the high temperature compression material 8 is disposed between the inner seal skin 9 and the outer seal skin 10. Usually, the material of the outer seal skin 10 has a larger coefficient of thermal expansion than the material of the inner seal skin 9, and therefore, at a high operating temperature of about 900 ° C., the inner seal skin 9 and the outer seal skin 10 are caused by a difference in thermal expansion. A gap is formed between It arrange | positions between an inner wall and an outer wall in the state which compressed the high temperature compression material 8 so that it might swell more than this clearance gap.

  In the fuel cell of FIG. 1, a high-temperature compression material is arranged around cell tubes and bundles, the inner wall is constructed around the high-temperature compression material in a compressed state, and a high-temperature compression material is arranged on the outer periphery of the inner wall. Then, it can be applied through a stage in which the outer wall is constructed around it in a state where it is compressed to a predetermined thickness, and a stage in which the outer wall is joined and integrated with the surrounding members by welding or the like.

  In general, a solid oxide fuel cell is accompanied by a gas header for supplying anode gas and cathode gas, which are battery reaction gases, and an exhaust gas combustion chamber for mixing and burning unreacted battery reaction gas.

  FIG. 1 shows a battery structure provided with these incidental facilities. In addition, a configuration in which the cell tube outer wall is an anode and the cell tube inner wall is a cathode is shown. In order to flow the anode gas to the outer wall of the cell tube, an anode gas header 4 is disposed in the lower part. In addition, a cathode gas header 5 and a cathode gas introduction pipe 6 are disposed on the upper part in order to flow the cathode gas to the inner wall of the cell pipe. Unreacted battery reaction gas is mixed and combusted in the upper exhaust gas combustion chamber 7 and discharged to the outside.

  For materials such as a gas header, an exhaust gas combustion chamber, and a gas introduction pipe, SUS materials are generally used from the viewpoint of securing strength and cost. Therefore, it is desirable to use a SUS-based material as the material of the outer seal skin 10 and integrate it into a welded structure or the like. Thereby, it is possible to prevent the battery reaction gas from leaking to the outside.

  On the other hand, ceramic materials are generally used as the material for the cell tube 1 and the bundle 2. Therefore, it is preferable to use a material having a thermal expansion coefficient equivalent to the material of the cell tube or bundle for the inner seal skin 9, and it is particularly preferable to use a metal material because it is easy to process into a container or to be easily welded. .

  For comparison, FIG. 2 shows a conventional solid oxide fuel cell having a pushing mechanism using a clamping spring. (A) is a plan view and (b) is an elevation view. Here, a clamping spring 11 and a clamping jig 12 are provided as a pushing mechanism. The fuel cell of this structure has a problem that a bypass flow is generated as described in the background art.

  Also in the present invention, it is possible to use such a pushing mechanism with a clamping spring in combination, and the effect of preventing bypass flow can be enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the solid oxide fuel cell by the Example of this invention, (a) is a top view, (b) is an elevation view. It is a block diagram of the conventional solid oxide fuel cell which has a pushing mechanism by a clamping spring, (a) is a top view, (b) is an elevation view.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cell pipe, 2 ... Bundle, 3 ... Current collector plate, 4 ... Anode gas header, 5 ... Cathode gas header, 6 ... Cathode gas introduction pipe, 7 ... Exhaust gas combustion chamber, 8 ... High temperature compression material, 9 ... Inner seal Skin, 10 ... outer seal skin, 11 ... clamping spring, 12 ... clamping jig.

Claims (4)

  In a solid oxide fuel cell in which a plurality of solid oxide fuel cells are combined and integrated to form a bundle, a plurality of bundles are arranged and stored in a cell container, and a battery reaction gas is allowed to flow around the cells. The cell container has a double structure composed of an inner wall and an outer wall, and is disposed between the inner wall and the outer wall in a compressed state of a compressible material that can be elastically deformed even at a battery operating temperature. A solid oxide fuel cell, wherein a compressible material that can be elastically deformed even at a battery operating temperature is disposed between an inner wall and the bundle in a compressed state. Solid oxide fuel cell according to claim 1, characterized by being configured of a material having a thermal expansion coefficient of the same or the like and the cell inner wall of the cell container.   3. The solid oxide fuel cell according to claim 2, wherein the outer wall of the cell container is formed of a SUS material constituting a gas header disposed above and below the cell.   2. The solid oxide fuel cell according to claim 1, wherein the cell is a cylindrical cell tube.

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