JP2014082201A - Fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell device that prevents damage to a seal member without reducing power generation efficiency.SOLUTION: A solid oxide fuel cell device 2 has a buffer section 34 for relaxing stress caused on a connecting portion between each fuel cell unit cell 84 and a fuel gas tank 68 by thermal expansion of conductive members (a collector 102 and an external terminal 104). The buffer section 34 is arranged at least either between each fuel cell unit cell 84 and a seal member 32 or between the seal member 32 and the fuel gas tank 68. In high-temperature conditions, the buffer section 34 is deformed so as to allow each fuel cell unit cell 84 to swing with respect to the fuel gas tank 68, while maintaining airtightness between the fuel cell unit cell 84 and the fuel gas tank 68.

Description

  The present invention relates to a solid oxide fuel cell device.

  A plurality of single cells (fuel cell) that can obtain electric power using fuel gas (hydrogen-containing gas) and air (oxygen-containing gas, oxidant gas) are accommodated in the casing, Various fuel cell devices that generate power by supplying fuel gas and air have been proposed. Among such fuel cell devices, in the solid oxide fuel cell device (SOFC), the internal temperature during operation rises from 700 degrees to nearly 1000 degrees. For this reason, a sealing material made of a brittle material (for example, glass) is used as a member for sealing the component. The following Patent Document 1 discloses a fuel cell device that seals between a ceramic or metal cell support plate (manifold top plate) and a fuel cell with a glass sealing material. A fuel cell device is disclosed in which a gap between a lower support plate (manifold top plate) made of fuel and a fuel battery cell is sealed with a glass sealing material. Patent Document 3 below discloses that a metal holding member and a fuel battery cell are made of glass. A fuel cell device that seals with a sealing material is disclosed.

JP 2007-265750 A JP 2010-97795 A JP 2005-183376 A

  In a fuel cell device in which a plurality of single cells are arranged upright on the upper surface of the manifold in a state of being substantially parallel to each other, and adjacent single cells are connected by a conductive member, There may be a problem that stress is concentrated on the connecting portion of the wire and the portion is damaged.

  This is because in a cell stack in which a plurality of single cells are arranged, the central portion tends to be hotter than the periphery of the arrangement, so that each single cell remains connected (constrained) by a conductive member. As a result of the difference in the amount of thermal expansion, the single cell oscillates around the connection portion (the lower end of the single cell) between each single cell and the manifold. If the sealing material disposed between the single cell and the manifold is damaged due to the swing, the internal fuel gas leaks, and the power generation performance of the fuel cell device is degraded.

  In order to prevent the cell from swinging as described above, the shape of the conductive member can be easily elastically deformed (for example, a bent plate shape or a bellows) so that the restraint of the cell by the conductive member is weakened. Shape). However, in that case, since the electrical resistance of the conductive member increases, there arises a problem that the power generation efficiency of the fuel cell device decreases.

  The present invention has been made in view of such problems, and an object thereof is to provide a fuel cell device capable of preventing the seal material from being damaged without lowering the power generation efficiency.

  In order to solve the above problems, a fuel cell device according to the present invention is a solid oxide fuel cell device, and includes a plurality of fuel cells arranged upright in a substantially parallel state to each other, and A lower end of the fuel battery cell is fixed, a manifold that supplies fuel gas from the lower end to the fuel battery cell, a sealing material that is disposed between the fuel battery cell and the manifold, and made of a brittle material, A conductive member that is disposed above the lower end of the fuel battery cell and connects the adjacent fuel battery cells, and is generated at a connection portion between the fuel battery cell and the manifold due to thermal expansion of the conductive member. A stress absorbing member for relieving stress, wherein the stress absorbing member is between the fuel cell and the sealing material or between the sealing material and the manifold. The fuel cell is allowed to swing with respect to the manifold while maintaining airtightness between the fuel cell and the manifold at a high temperature. It is characterized by being deformed.

  The fuel cell device according to the present invention is a solid oxide fuel cell device, and includes a fuel cell and a manifold.

  A plurality of fuel cells are provided, and are arranged upright on a manifold, which will be described later, in a state substantially parallel to each other. The fuel cell is a so-called single cell, and each generates power by receiving supply of fuel gas and oxidant gas.

  The manifold is a container for supplying fuel gas to the fuel cells. The lower end of each fuel cell is fixed to the upper surface of the manifold, and fuel gas is supplied to each fuel cell from the lower end. Further, a sealing material made of a brittle material is disposed between each fuel cell and the manifold. As such a sealing material, for example, glass or ceramics is used.

  Adjacent fuel cells are connected by a conductive member. The conductive member is disposed above the lower end of the fuel cells, and mechanically and electrically connects the fuel cells. Since the fuel cells are electrically connected by the conductive member, it is possible to output high-voltage power from the entire fuel cell (cell stack).

  By the way, in the fuel cell device having such a configuration, the temperature of each fuel cell varies during operation, resulting in a difference in thermal expansion amount of each fuel cell. However, since adjacent fuel cells are connected (restrained) to each other by the conductive member, the fuel cells swing with thermal expansion, and stress is applied to the connection portion between the fuel cells and the manifold. May occur. Therefore, the fuel cell device according to the present invention further includes a stress absorbing member for relieving such stress.

  The stress absorbing member is disposed at least one of between the fuel battery cell and the sealing material or between the sealing material and the manifold. At high temperatures (during operation of the fuel cell device), the stress absorbing member is deformed so as to allow the fuel cell to swing with respect to the manifold while maintaining airtightness between the fuel cell and the manifold. To do.

  As described above, when the fuel cell swings due to the difference in thermal expansion amount, the stress absorbing member is deformed to allow the swing, so that the connecting portion between the fuel cell and the manifold The stress at is reliably relieved. As a result, it is possible to prevent the fuel gas from leaking due to breakage of the sealing material.

  Further, the shape of the conductive member does not have to be a shape that can be easily elastically deformed, and can be a simple flat plate, for example. For this reason, the electric resistance of the conductive member does not increase, and the power generation efficiency of the fuel cell device does not decrease.

  In the fuel cell device according to the present invention, it is also preferable that the sealing material and the stress absorbing member are stacked in the vertical direction, and the stacked surface is horizontal.

  The sealing material and the stress absorbing member support the fuel cell from below, and a force (gravity) along the vertical direction is always applied thereto. For this reason, when the state in which the stress absorbing member is at a high temperature is continued for a long time during the operation of the fuel cell device, the stress absorbing member may be gradually deformed due to the influence of gravity.

  In particular, when the laminated surface of the sealing material and the stress absorbing member is inclined (or vertical) with respect to the horizontal plane, a shearing force is applied to the stress absorbing member along the laminated surface. May sink down gradually.

  Therefore, in this preferred embodiment, the sealing material and the stress absorbing member are laminated in the vertical direction, and the laminated surface is horizontal. For this reason, the direction of gravity applied to the stress absorbing member is perpendicular to the laminated surface. That is, almost no shear force due to gravity (along the laminated surface) is applied to the stress absorbing member. As a result, a phenomenon that the fuel battery cell sinks downward little by little does not occur.

  In the fuel cell device according to the present invention, a metal member is connected to a lower end of the fuel cell, and an area of a portion of the metal member that is joined to the stress absorbing member or the sealing material. Is preferably larger than the area of the lower end surface of the fuel cell.

  In this preferred embodiment, a metal member is connected to the lower end of the fuel cell. Of this metal member, the area of the portion joined to the stress absorbing member or the sealing material, that is, the joint area with the member joined from the lower side to the metal member is the area of the lower end surface of the fuel cell. Bigger than. Since the lower end of the fuel battery cell is supported by a wider area, the fuel battery cell can be stabilized, and seal failure (breakage of the sealing material, etc.) accompanying the oscillation of the fuel battery cell can be further suppressed.

  In the fuel cell device according to the present invention, the metal member has an extension portion formed to extend downward, and the upper surface of the manifold has each of the fuel cell units. The fuel cell is fixed to the manifold with the extension portion inserted into the opening, and a gap is formed between the side surface of the extension portion and the edge of the opening. It is also preferable that is formed.

  In this preferred embodiment, the metal member has an extension portion formed so as to extend downward. In addition, openings corresponding to the respective fuel cells are formed on the upper surface of the manifold. The fuel battery cell is fixed to the manifold in a state where the extension portion of the metal member is inserted into the opening of the manifold.

  With such a configuration, even when the inside of the fuel cell device becomes high temperature and the fuel cell or the conductive member is thermally expanded, the lower end position of the fuel cell is greatly displaced in the horizontal direction ( Misalignment) is prevented.

  Further, a gap is formed between the side surface of the extension and the edge of the opening. Since the degree of freedom for the fuel cell to swing to some extent is ensured, damage to the metal member and the manifold at high temperatures is prevented.

  In the fuel cell device according to the present invention, the stress absorbing member is preferably silver.

  When silver is used as the stress absorbing member, the stress absorbing member does not melt even near the SOFC operating temperature of 700 ° C., and the airtightness between the fuel cell and the manifold can be maintained. . Even when the fuel cell is swung around its lower end, the stress absorbing member is easily deformed (due to the ductility of silver), so that the sealing material breaks and the fuel gas leaks. There is nothing.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell apparatus which can prevent the failure | damage of a sealing material can be provided, without reducing electric power generation efficiency.

1 is a perspective view showing an appearance of a fuel cell device including a fuel cell module in an embodiment of the present invention. It is sectional drawing in the center vicinity of FIG. 1, Comprising: It is sectional drawing which shows the cross section seen from the A direction of FIG. It is sectional drawing in the center vicinity of FIG. 1, Comprising: It is sectional drawing which shows the cross section seen from the B direction of FIG. It is a perspective view which shows the state which removed some outer plates from the casing of FIG. It is a fragmentary sectional view which shows the fuel cell unit used for this embodiment. It is a perspective view which shows the structure of the fuel cell stack in this embodiment. It is a fragmentary sectional view which shows the cap part and holding | maintenance part in this embodiment. It is a schematic diagram which shows the joining state of a cap part and a buffer part. It is a schematic diagram which shows the joining state of a cap part and a buffer part. FIG. 3 is a schematic diagram corresponding to FIG. 2, and is a schematic diagram showing flows of power generation air and combustion gas. FIG. 4 is a schematic diagram corresponding to FIG. 3, and is a schematic diagram showing flows of power generation air and combustion gas. It is a fragmentary sectional view which shows the cap part and holding | maintenance part in other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  First, a fuel cell device according to an embodiment of the present invention will be described with reference to FIG. A fuel cell device 2 shown in FIG. 1 constitutes a part of a solid oxide fuel cell unit. This solid oxide fuel unit includes a fuel cell device 2 and an auxiliary unit (not shown).

  In FIG. 1, the height direction of the fuel cell device 2 is the y-axis direction. The x axis and the z axis are defined along a plane perpendicular to the y axis, the direction along the short direction of the fuel cell device 2 is defined as the x axis direction, and the direction along the longitudinal direction of the fuel cell device 2 is defined as z. Axial direction. The x-axis, y-axis, and z-axis described in FIG. 2 and thereafter are based on the x-axis, y-axis, and z-axis in FIG. Further, the direction along the negative direction of the z axis is the A direction, and the direction along the positive direction of the x axis is the B direction.

  The fuel cell device 2 includes a casing 56 that houses fuel cells (details will be described later), and a heat exchanger 22 provided on the upper portion of the casing 56. The inside of the casing 56 is a sealed space. A reformed gas supply pipe 60 and a water supply pipe 62 are connected to the casing 56. On the other hand, a power generation air introduction pipe 74 and a combustion gas discharge pipe 82 are connected to the heat exchanger 22.

  The to-be-reformed gas supply pipe 60 is a pipe line that supplies a to-be-reformed gas for reforming such as city gas into the casing 56. The water supply pipe 62 is a pipe for supplying water used when steam reforming the gas to be reformed. The power generation air introduction pipe 74 is a pipe for supplying power generation air (oxidant gas) for causing a power generation reaction with the reformed fuel gas. The combustion gas discharge pipe 82 is a pipe line that discharges the combustion gas generated as a result of combustion of the fuel gas after the power generation reaction.

  Next, the inside of the fuel cell device 2 will be described with reference to FIGS. 2 is a cross-sectional view of the fuel cell device 2 as viewed from the direction A in FIG. 1 in the vicinity of the center thereof. 3 is a cross-sectional view of the fuel cell device 2 as viewed from the direction B in FIG. 1 in the vicinity of the center thereof. FIG. 4 is a perspective view showing a state where a part of the casing 56 covering the fuel cell assembly is removed from the fuel cell device 2 shown in FIG.

  As shown in FIGS. 2 to 4, the fuel cell assembly 12 of the fuel cell device 2 is entirely covered with a casing 56. As shown in FIG. 4, the fuel cell assembly 12 as a whole has a substantially rectangular parallelepiped shape that is longer in the A direction than in the B direction. The upper surface on the reformer 20 side and the lower surface on the fuel gas tank 68 (gas manifold) side. , A long side surface extending along the direction A in FIG. 4 and a short side surface extending along the direction B in FIG.

  In the present embodiment, an evaporating mixer (not explicitly shown) for evaporating the water supplied from the water supply pipe 62 is provided inside the reformer 20. The evaporative mixer is heated by the combustion gas to convert water into water vapor, and to mix this water vapor with fuel gas (city gas) that is a reformed gas and air.

  The reformed gas supply pipe 60 and the water supply pipe 62 are both connected to the reformer 20 after being led into the casing 56. More specifically, as shown in FIG. 3, the reformer 20 is connected to an end on the right side in the drawing, which is an upstream end of the reformer 20.

  The reformer 20 is disposed further above the combustion chamber 18 formed above the fuel cell assembly 12. Accordingly, the reformer 20 is heated by the combustion heat of the remaining fuel gas and air after the power generation reaction, and is configured to serve as an evaporative mixer and a reformer that causes a reforming reaction. Has been.

  The upper end of the fuel supply pipe 66 is connected to the downstream end of the reformer 20 (the left end in FIG. 3). The lower end side 66 a of the fuel supply pipe 66 is disposed so as to enter the fuel gas tank 68.

  As shown in FIGS. 2 to 4, the fuel gas tank 68 is provided directly below the fuel cell assembly 12. The fuel gas tank 68 distributes and supplies fuel gas to each fuel cell as follows. A plurality of small holes (not shown) are formed in the outer periphery of the lower end side 66a of the fuel supply pipe 66 inserted into the fuel gas tank 68 along the longitudinal direction (A direction). The fuel gas reformed by the reformer 20 is uniformly supplied in the longitudinal direction into the fuel gas tank 68 through the plurality of small holes (not shown). The fuel gas supplied to the fuel gas tank 68 passes through the opening of the holding portion 30 that is a part of the fuel gas tank 68 and then is located inside each fuel cell unit 16 constituting the fuel cell assembly 12. It is supplied into a flow path (details will be described later), and moves up in the fuel cell unit 16 to reach the combustion chamber 18.

  Next, the fuel cell unit 16 will be described with reference to FIG. FIG. 5 is a partial cross-sectional view showing the fuel cell unit 16 of the present embodiment.

  As shown in FIG. 5, the fuel cell unit 16 includes a fuel cell 84 and inner electrode terminals 86 respectively connected to the vertical ends of the fuel cell 84.

  The fuel cell 84 is a tubular structure extending in the vertical direction, and includes a cylindrical inner electrode layer 90 that forms a fuel gas flow path 88 therein, a cylindrical outer electrode layer 92, an inner electrode layer 90, and an outer side. An electrolyte layer 94 is provided between the electrode layer 92 and the electrode layer 92. The inner electrode layer 90 is a fuel electrode through which fuel gas passes and becomes a (−) electrode, while the outer electrode layer 92 is an air electrode in contact with air and becomes a (+) electrode.

  Since the inner electrode terminals 86 attached to the upper end side and the lower end side of the fuel cell unit 16 have the same structure, the inner electrode terminal 86 attached to the lower end side will be specifically described here. The lower part 90 a of the inner electrode layer 90 includes an outer peripheral surface 90 b and a lower end surface 90 c exposed to the electrolyte layer 94 and the outer electrode layer 92. The inner electrode terminal 86 is connected to the outer peripheral surface 90b of the inner electrode layer 90 through a conductive sealing material 96, and is further in direct contact with the lower end surface 90c of the inner electrode layer 90 so as to be electrically connected to the inner electrode layer 90. It is connected to the. A fuel gas passage 98 communicating with the fuel gas passage 88 of the inner electrode layer 90 is formed at the center of the inner electrode terminal 86. The inner electrode terminal 86 and the conductive sealing material 96 constitute a conductive cap portion 36 that covers the end of the fuel cell 84.

  The inner electrode layer 90 includes, for example, a mixture of Ni and zirconia doped with at least one selected from rare earth elements such as Ca, Y, and Sc, and Ni and ceria doped with at least one selected from rare earth elements. The mixture is formed of at least one of Ni and a mixture of lanthanum garade doped with at least one selected from Sr, Mg, Co, Fe, and Cu.

  The electrolyte layer 94 is, for example, zirconia doped with at least one selected from rare earth elements such as Y and Sc, ceria doped with at least one selected from rare earth elements, lanthanum gallate doped with at least one selected from Sr and Mg, Formed from at least one of the following.

  The outer electrode layer 92 includes, for example, lanthanum manganite doped with at least one selected from Sr and Ca, lanthanum ferrite doped with at least one selected from Sr, Co, Ni and Cu, Sr, Fe, Ni and Cu. It is formed from at least one of lanthanum cobaltite doped with at least one selected from the group consisting of silver and silver.

  Next, the fuel cell stack 14 will be described with reference to FIG. FIG. 6 is a perspective view showing the fuel cell stack 14 of the present embodiment.

  As shown in FIG. 6, the fuel cell stack 14 includes 16 fuel cell units 16, and the lower end side and the upper end side of these fuel cell units 16 are respectively made of metal fuel gas tank upper plate 68 a and It is supported by the upper support plate 100. The fuel gas tank upper plate 68a and the upper support plate 100 are formed with through holes (openings) through which the inner electrode terminal 86 can pass.

  Further, a current collector 102 is attached to an upper portion of the fuel cell unit 16. The current collector 102 electrically and mechanically connects adjacent fuel cell units 16. The current collector 102 electrically and mechanically connects the inner electrode terminal 86 attached to the inner electrode layer 90 that is a fuel electrode and the outer peripheral surface of the outer electrode layer 92 that is the air electrode of the adjacent fuel cell unit 16. Connected.

  Further, the external terminals 104 are connected to the inner electrode terminals 86 at the upper and lower ends of the two fuel cell units 16 located at the ends of the fuel cell stack 14. These external terminals 104 are connected to the outer electrode layer 92 of the fuel cell unit 16 at the end of the adjacent fuel cell stack 14. As a result, all 160 fuel cell units 16 are connected in series.

  As described above, the current collector 102 and the external terminal 104 are arranged above the lower end of the fuel cell unit 16 (the connection portion with the fuel gas tank 68), and the adjacent fuel cell units are thereby arranged. 16 are electrically and mechanically connected. That is, the current collector 102 and the external terminal 104 correspond to the conductive member of the present invention.

  The lower end of the fuel cell unit 16 is fixed to the holding portion 30 disposed on the fuel gas tank upper plate 68a. The holding portion 30 is formed with a through hole penetrating in the vertical direction, and the internal space of the fuel gas tank 68 and the fuel gas flow path 98 communicate with each other through the through hole.

  The holding portion 30 is a member used when the inner electrode terminal 86 of the fuel cell unit 16 is inserted and fixed into the through hole of the fuel gas tank upper plate 68a. That is, the holding unit 30 is used as a member that holds the fuel cell unit 16 in the fuel gas tank 68.

  The cap part 36 and the holding part 30 will be described with reference to FIG. FIG. 7 is a partial cross-sectional view showing the cap part 36 and the holding part 30 of the present embodiment. The fuel cell unit 17 including the cap portion 36 and the holding portion 30 constitute the fuel cell module 17.

  As shown in FIG. 7, a seal portion 32 is disposed between the cap portion 36 and the holding portion 30. The seal portion 32 seals (air-tightens) between the fuel cell unit 16 and the fuel gas tank 68 in order to prevent leakage of fuel gas. As a material of the seal portion 32, a brittle material such as glass or ceramics can be used. Here, “glass” is a concept including amorphous glass, crystallized glass, and glass in which amorphous and crystalline are mixed. The “amorphous glass” is a concept including not only amorphous (glass having a glass transition Tg) exhibiting a glass transition (a glass in a narrow sense) but also amorphous having no glass transition.

  By the way, in the fuel cell device 2 configured as described above, the temperature of each fuel cell unit 16 varies during operation, resulting in a difference in the amount of thermal expansion of each fuel cell unit 16. However, since the adjacent fuel cell units 16 are connected (restrained) to each other by the conductive members (the current collector 102 and the external terminal 104), the fuel cell units 16 fluctuate with thermal expansion. In some cases, the fuel cell unit 16 may oscillate around the connecting portion with the fuel gas tank 68 (the lower end of the fuel cell unit 16). As a result, stress concentrates on the connecting portion between the fuel cell unit 16 and the fuel gas tank 68, the connecting portion (especially the seal portion 32) is damaged, and the fuel gas leaks from the inside. It is done.

  Further, the glass or ceramic used as the material of the seal portion 32 has characteristics that the coefficient of thermal expansion is smaller and the Young's modulus is lower than the metal used as the material of the cap portion 36. Therefore, when the gap between the cap portion 36 and the holding portion 30 is sealed only by the seal portion 32, the difference in thermal expansion between the seal portion 32 and the cap portion 36 becomes large at a high temperature during operation of the fuel cell. The stress generated between the seal part 32 and the cap part 36 is further increased.

  Therefore, in the fuel cell device 2, the occurrence of stress as described above is suppressed by disposing the buffer portion 34 between the seal portion 32 and the cap portion 36. As shown in FIG. 7, the seal part 32 and the buffer part 34 are laminated | stacked on the up-down direction, and the lamination | stacking surface is horizontal.

  The buffer portion 34 is a metal member disposed between the seal portion 32 and the cap portion 36 in order to absorb the stress generated at the connection portion between the fuel cell unit 16 and the fuel gas tank 68. As a material of the buffer portion 34, silver, an alloy containing silver as a main component, a material obtained by adding a small amount (several mass%) of a metal oxide to an alloy containing silver or silver as a main component, or a ductile material such as gold or platinum. High metal can be applied. By using such a material, the stress generated in the seal portion 32 can be stably absorbed even in the temperature distribution during operation of the solid oxide fuel cell device 2 having a high operation temperature.

  When the temperature is high (while the fuel cell device 2 is operating), the buffer 34 maintains the airtightness between the fuel cell unit 16 and the fuel gas tank 68, while the fuel cell unit 16 shakes against the fuel gas tank 68. Deform to allow movement.

  As described above, when the fuel cell unit 16 swings due to the difference in the amount of thermal expansion, the buffer unit 34 is deformed to allow the swing, so that the fuel cell unit 16 and the fuel The stress at the connection portion with the gas tank 68 is reliably relieved. As a result, it is possible to prevent the fuel gas from leaking due to the seal portion 32 being damaged.

  Further, the shape of the conductive member (the current collector 102 and the external terminal 104) does not have to be a shape that can be easily elastically deformed, and can be a simple flat plate shape as shown in FIG. For this reason, the electrical resistance of the conductive member (the current collector 102 and the external terminal 104) does not increase, and the power generation efficiency of the fuel cell device 2 does not decrease.

  The material of the buffer part 34 is a softer material than the metal that is the material of the cap part 36 or the glass that is the material of the seal part 32, and even if the cap part 36 and the seal part 32 are thermally expanded at high temperatures, It is desirable to select from a material (buffer material) that can be deformed while following both thermal expansions.

  Of the lower surface of the cap part 36, the area of the joined part 37 that is a part joined to the buffer part 34 is larger than the area of the lower end face 90 c of the fuel cell 84. For this reason, the force transmitted from the lower end surface 90c of the fuel cell 84 to the seal portion 32 is dispersed. Further, since the lower end of the fuel battery cell 84 is supported by a wider area, the fuel battery cell 84 can be stabilized, and the seal failure (breakage of the seal portion 32, etc.) accompanying the swinging of the fuel battery cell 84 is further suppressed. Has been.

  The cap part 36 has an extension part 38 formed so as to extend downward. The extension 38 has a cylindrical shape, and the central axis thereof coincides with the central axis of the fuel cell 84. Further, the diameter (outer diameter) of the extension portion 38 is slightly smaller than the diameter (inner diameter) of the opening formed in the holding portion 30. The fuel cell unit 16 is fixed to the upper surface of the fuel gas tank 68 with the extended portion 38 inserted into the opening of the holding portion 30.

  With such a configuration, even when the inside of the fuel cell device 2 becomes high temperature and the fuel cell unit 16, the conductive member (the current collector 102, the external terminal 104) and the like are thermally expanded, the fuel cell unit The lower end position of 16 is not greatly displaced in the horizontal direction (position shift).

  Further, a gap (not shown) is formed between the side surface of the extension portion 38 and the edge (inner side surface) of the opening of the holding portion 30. With such a configuration, a degree of freedom for the fuel cell unit 16 to swing to some extent is secured, so that the cap part 36 and the fuel gas tank 68 (holding part 30) are prevented from being damaged at high temperatures.

  Further, for example, when the temperature distribution is generated in the cell stack during operation and the fuel cell 84 receives stress, and the fuel cell 84 tilts or moves, the cap portion 36 is fixed to the fuel cell 84. Therefore, the extension portion 38 of the cap portion 36 tends to tilt as the posture of the fuel battery cell 84 changes. However, since the extension portion 38 is fitted into the opening of the holding portion 30, it is extended by the holding portion 30. The change in the posture of the portion 38 is hindered. Further, the change in the posture of the fuel cell 84 is more greatly influenced on the tip side (the holding portion 30 side) than on the base side (the fuel cell 84 side) of the extension portion 38, but the change in the posture is large. Since the tip end side is held by the holding portion 30 and the seal portion 32 is arranged on the base side where the change in posture is small, the seal portion 32 is not stressed, and the change in the posture of the fuel cell 84 is It can be suppressed by the holding unit 30. Thus, since the change of the attitude | position of the fuel battery cell 84 can be suppressed, the stress which generate | occur | produces in the seal part 32 can be suppressed and the damage of the seal part 32 can be prevented.

  A method of forming the buffer portion 34 when manufacturing the fuel cell module 17 will be described below.

  First, a layer as the buffer portion 34 is formed by applying a silver paste to the cap portion 36 or the like. Subsequently, the cap part 36 and the seal part 32 are arranged and bonded so as to sandwich the layer as the buffer part 34. Thereby, the buffer part 34 can be formed between the cap part 36 and the seal | sticker part 32 like this embodiment shown in FIG.

  By the way, when the buffer part 34 is formed, the adhesive strength between the cap part 36 and the seal part 32 can be increased by applying the silver paste to the cap part 36 side instead of the seal part 32 side. This is because the surface roughness of the metal cap portion 36 is larger than the surface roughness of the glass seal portion 32.

  More specifically, when the cap part 36 is joined after the silver paste is applied to the seal part 32 side, the cap part 36 and the buffer part 34 are placed in a region where the cap part 36 and the buffer part 34 face each other as shown in FIG. A point contact region is formed in which the portion 36 and the buffer portion 34 are in contact with each other at an uneven vertex on the surface of the cap portion 36.

  On the other hand, when the seal part 32 is joined after the silver paste is applied to the cap part 36 side, the buffer part 34 can be formed while filling the unevenness on the surface of the cap part 36 with a soft silver paste. it can. Therefore, in this case, as shown in FIG. 9, a close contact area where the cap part 36 and the buffer part 34 firmly adhere to each other can be formed in the area where the cap part 36 and the buffer part 34 face each other.

  Even if a point contact region is formed between the seal part 32 and the buffer part 34 by applying the silver paste to the cap part 36 and then joining the seal part 32, the high temperature during the fuel cell operation As a result, the seal portion 32 is softened, so that a close contact area between the seal portion 32 and the buffer portion 34 can be formed between the seal portion 32 and the buffer portion 34.

  Thus, by forming the contact | adherence area | region where the cap part 36 and the buffer part 34 adhere firmly, the airtightness between the fuel cell unit 16 and the fuel gas tank 68 can be hold | maintained firmly.

  Further, as shown in FIG. 12A, a layer as the buffer part 34 is formed by applying silver paste on the upper surface of the holding part 30, and then the holding part so as to sandwich the layer as the buffer part 34. 30 and the seal portion 32 may be arranged and joined. Thereby, the buffer part 34 can be formed between the holding part 30 and the seal part 32. Also in this case, since the surface roughness of the holding portion 30 is larger than the surface roughness of the glass seal portion 32 as described in the above-described embodiment, the holding portion 30 and the buffer portion 34 are in close contact with each other. Regions can be formed. By forming the close contact region, the airtightness between the fuel cell unit 16 and the fuel gas tank 68 can be firmly maintained.

  Further, as shown in FIG. 12B, a layer as a buffer portion 34 is formed by applying silver paste on both the lower surface of the cap portion 36 and the upper surface of the holding portion 30, respectively, and then the buffer portion. The buffer portion 34 may be formed between the cap portion 36, the seal portion 32, and the holding portion 30 so as to sandwich the layer 34. In this case, since the close contact regions can be formed on both sides of the cap portion 36 and the buffer portion 34 and between the holding portion 30 and the buffer portion 34, the fuel cell unit 16 is further increased. And the gas tightness between the fuel gas tank 68 can be firmly maintained.

  Next, a structure for supplying power generation air to the inside of the fuel cell device 2 will be described with reference to FIGS. 2 to 4, 10, and 11. FIG. 10 is a schematic diagram corresponding to FIG. 2 and shows the flow of power generation air and combustion gas. FIG. 11 is a schematic diagram corresponding to FIG. 3, and similarly shows the flow of power generation air and combustion gas. As shown in these drawings, a heat exchanger 22 is provided above the reformer 20. The heat exchanger 22 is provided with a plurality of combustion gas pipes 70 and a power generation air flow path 72 formed around the combustion gas pipes 70.

  A power generation air introduction pipe 74 is attached to one end side (the right end in FIGS. 3 and 11) on the upper surface of the heat exchanger 22. With this power generation air introduction pipe 74, power generation air is introduced into the heat exchanger 22 from a power generation air flow rate adjustment unit (not shown).

  As shown in FIG. 2, a pair of outlet ports 76 a of the power generation air flow path 72 is formed on the other end side (the left end in FIGS. 3 and 11) on the upper side of the heat exchanger 22. The outlet port 76a is connected to a pair of communication channels 76. Further, a power generation air supply passage 77 is formed on the outer sides of both sides of the casing 56 of the fuel cell device 2 in the width direction (B direction: short side surface direction).

  Therefore, power generation air is supplied to the power generation air supply path 77 from the outlet port 76 a of the power generation air flow path 72 and the communication flow path 76. The power generation air supply path 77 is formed along the longitudinal direction of the fuel cell assembly 12. Furthermore, in order to blow out the air for power generation toward each fuel cell unit 16 of the fuel cell assembly 12 in the power generation chamber 10 at a position corresponding to the lower side of the fuel cell assembly 12 below the fuel cell assembly 12. A plurality of outlets 78a and 78b are formed. The power generation air blown out from these air outlets 78a and 78b flows upward along the outside of each fuel cell unit 16.

  Subsequently, a structure for discharging combustion gas generated by combustion of fuel gas and power generation air will be described. The combustion gas generated above the fuel cell unit 16 rises in the combustion chamber 18 and reaches the rectifying plate 21. The rectifying plate 21 is provided with an opening 21a, and combustion gas is guided into the opening 21a. The combustion gas that has passed through the opening 21 a reaches the other end side of the heat exchanger 22. In the heat exchanger 22, a plurality of combustion gas pipes 70 are provided for discharging combustion gas generated by combustion of fuel gas and power generation air in the combustion chamber 18. A combustion gas discharge pipe 82 is connected to the downstream end side of these combustion gas pipes 70 so that the combustion gas is discharged to the outside.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

2: Fuel cell device 10: Power generation chamber 12: Fuel cell assembly 14: Fuel cell stack 16: Fuel cell unit 17: Fuel cell module 18: Combustion chamber 20: Reformer 21: Rectifying plate 21a: Opening 22: Heat exchanger 30: Holding part 32: Sealing part 34: Buffer part 36: Cap part 37: Part to be joined 38: Extension part 56: Casing 60: Reformed gas supply pipe 62: Water supply pipe 66: Fuel supply Pipe 66a: Lower end side 68: Fuel gas tank 68a: Fuel gas tank upper plate 70: Combustion gas pipe 72: Power generation air flow path 74: Power generation air introduction pipe 76: Communication flow path 76a: Outlet port 77: Power generation air supply path 78a, 78b: Air outlet (airflow generator)
82: Combustion gas discharge pipe 84: Fuel cell 86: Inner electrode terminal 88: Fuel gas flow path 90: Inner electrode layer 90a: Lower part 90b: Outer peripheral surface 90c: Lower end surface 92: Outer electrode layer 94: Electrolyte layer 96: Seal Material 98: Fuel gas flow path 100: Upper support plate 102: Current collector 104: External terminal

Claims (5)

A solid oxide fuel cell device comprising:
A plurality of fuel cells arranged upright in a substantially parallel state;
A lower end of each of the fuel cells is fixed, a manifold for supplying fuel gas from the lower end to the fuel cells,
A sealing material made of a brittle material, disposed between the fuel cell and the manifold;
A conductive member disposed above the lower end of the fuel cell and connecting the adjacent fuel cells; and
A stress absorbing member for relieving stress generated in a connection portion between the fuel battery cell and the manifold in association with thermal expansion of the conductive member,
The stress absorbing member is
Between the fuel cell and the seal material, or at least one of the seal material and the manifold,
The fuel cell is deformed to allow the fuel cell to swing with respect to the manifold while maintaining airtightness between the fuel cell and the manifold at a high temperature. A fuel cell device.   2. The fuel cell device according to claim 1, wherein the sealing material and the stress absorbing member are laminated in a vertical direction, and a laminated surface thereof is horizontal. A metal member is connected to the lower end of the fuel cell,
3. The fuel according to claim 2, wherein an area of a portion of the metal member joined to the stress absorbing member or the sealing material is larger than an area of a lower end surface of the fuel cell. Battery device. The metal member has an extension formed to extend downward,
An opening corresponding to each of the fuel cells is formed on the upper surface of the manifold,
The fuel cell is fixed to the manifold with the extension portion inserted into the opening,
The fuel cell device according to claim 3, wherein a gap is formed between a side surface of the extension and an edge of the opening.   The fuel cell apparatus according to claim 4, wherein the stress absorbing member is silver.

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