JP2017152096A - Fuel battery cell stack and solid oxide fuel battery cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow for maintaining output of excellent power from a fuel battery cell even when the fuel battery cell is exposed to abrupt thermal fluctuation due to power generation reaction.SOLUTION: A fuel battery cell stack comprises: a cylindrical fuel battery cell 84 including an inner electrode layer (fuel electrode layer) 90, an outer electrode layer (air layer) 92, and an electrolyte layer 94; and an inner electrode terminal 86 provided so as to surround both end parts of the fuel battery cell 84 and for extracting power from the fuel battery cell 84. The fuel battery cell 84 is electrically connected to the inner electrode terminal 86 via a flexible silver foil 91. The silver foil 91 is connected to the fuel battery cell 84 and the inner electrode terminal 86 by silver pastes 93A and 93B. The silver foil 91 connects between the fuel battery cell 84 and the inner electrode terminal 86 in a bent state. The silver foil 91 also connects the fuel battery cell 84 to the inner electrode terminal 86 so that a lower surface of the fuel battery cell 84 becomes displaceable to a bottom surface of the inner electrode terminal 86 facing the lower surface.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a fuel cell stack and a solid oxide fuel cell device including the fuel cell stack.

  A solid oxide fuel cell device (hereinafter also referred to as “SOFC”) uses an oxide ion conductive solid electrolyte as an electrolyte, has electrodes attached to both sides thereof, and supplies fuel gas to one side. In this fuel cell, an oxidant gas (air, oxygen, etc.) is supplied to the other side, and electricity is generated by a reaction between the fuel gas and the oxidant gas.

  The electric power generated from the fuel cell is connected to a fuel electrode layer and an air electrode layer that constitute the fuel cell and a current collecting member is taken out through the current collecting member. As a configuration for taking out the electric power generated from such a fuel battery cell, for example, in Patent Document 1, a cylindrical fuel battery cell has a silver space between an inner electrode layer (fuel electrode layer) and an inner electrode terminal. A configuration is disclosed in which a silver sealing material formed by sintering brazing is electrically connected.

  Further, in Patent Document 2, in a flat fuel cell, a foil-shaped metal having an annular insulating barrier layer formed on the outer edge of a circular electrolyte layer and having a through hole above the insulating barrier layer. The structure which laminated | stacked foil and formed the air electrode layer into a film so that the inner edge part of an electrolyte layer and metal foil was covered is disclosed.

  Further, in Patent Document 3, in a flat fuel cell, a metal current collector provided with a metal foil is disposed between a connector plate and an electrode layer (air electrode layer), and the generated power generation gas is supplied. A configuration is disclosed in which a metal foil expands toward the electrode layer due to pressure so that the electrode layer and the metal foil come into contact with each other and the generated electric power is taken out.

International Publication No. 2013/047667 JP 2005-190862 A JP 2013-157234 A

  Here, the fuel cell of the solid oxide fuel cell device generates heat up to a high temperature of 700 ° C. or higher during power generation. For this reason, the solid oxide fuel cell stack is required to have a performance capable of withstanding repeated rapid thermal fluctuations between an outside air temperature or room temperature and a high temperature of 700 ° C. or higher. So far, thermal stress has been suppressed by configuring the components used in the solid oxide fuel cell device with materials having a similar coefficient of thermal expansion.

  However, regarding the conductive structure that electrically connects the fuel cell as described above and a current collecting member for taking out the electric power generated from the fuel cell, the thermal expansion coefficient is close while maintaining these functions. It was extremely difficult to select such a material. For this reason, a thermal stress is generated between the current collecting member and the fuel battery cell, and the fuel battery cell is damaged due to the occurrence of a crack, or the electrical connection state between the fuel battery cell and the current collecting member is impaired. was there.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to maintain a good power output from the fuel cell even when exposed to a rapid thermal fluctuation due to a power generation reaction. .

  The fuel cell stack according to the present invention is a fuel cell stack that generates power using fuel gas and oxidant gas, and includes a fuel electrode layer having a fuel passage to which fuel gas is supplied, and air to which oxidant gas is supplied. A cylindrical fuel cell having a polar layer and a solid electrolyte layer provided between the fuel electrode layer and the air electrode layer, and a fuel cell provided so as to surround at least one end of the fuel cell. A power collecting member for taking out the electric power generated by the cell from the fuel cell, and the fuel cell is electrically connected to the current collecting member through a flexible foil-like metal member, The metal member is connected to the fuel cell and the current collecting member by a conductive paste, and the foil-like metal member is connected between the fuel cell and the current collecting member in a bent state. Follow the applied stress The foil-shaped metal member can collect the fuel cell so that the upper surface or the lower surface of the fuel cell can be displaced with respect to the top surface or the bottom surface of the current collector facing the upper surface or the lower surface. It connects to a member, It is characterized by the above-mentioned.

  As described above, since the fuel cell generates heat up to a high temperature of 700 ° C. or higher during power generation, thermal stress is generated between the current collecting member and the fuel cell having different thermal expansion coefficients. In particular, conductive brazing and paste for attaching a foil-like metal member to a fuel cell and a current collecting member have a different thermal expansion coefficient from other members, so that thermal deformation is likely to occur when exposed to high temperatures. .

  On the other hand, according to the present invention having the above configuration, since the fuel cell and the current collecting member are connected in a state where the metal member is bent, the fuel cell is different due to a difference in thermal expansion coefficient at a high temperature. Even if a displacement occurs between the cell and the current collecting member, it can be absorbed. Furthermore, even if the conductive brazing or paste for attaching the foil-shaped metal member to the fuel cell and the current collecting member is thermally deformed, the foil-shaped metal member may be deformed following the thermal deformation. it can. For this reason, it is possible to prevent thermal stress from acting on the fuel cell and to prevent the metal member from peeling off.

  Here, unless the fuel cell and the current collecting member can be displaced, the metal member cannot sufficiently absorb the thermal stress. However, if an interval is provided between the fuel battery cell and the current collecting member, the distance between the fuel battery cell and the current collecting member varies among the plurality of fuel battery cells. Variations in dimensions occur every time.

  On the other hand, according to the present invention, the foil-shaped metal member can be connected to the current collecting member so that the upper surface or the lower surface of the fuel cell can be displaced with respect to the top surface or the bottom surface of the current collecting member. Therefore, thermal stress can be sufficiently absorbed by the metal member. Furthermore, since the upper surface or the lower surface of the fuel cell can be displaced with respect to the top surface or the bottom surface of the current collecting member in this way, it is possible to absorb the variation in the distance between the fuel cell and the current collecting member. . In particular, in the manufacturing process of the fuel cell, the variation in the size of the fuel cell can be reduced by bringing the upper surface or the lower surface of the fuel cell into contact with the top surface or the bottom surface of the current collecting member.

In the present invention, preferably, the foil-shaped metal member is connected in contact with the upper surface or the lower surface of the fuel cell, and the foil-shaped metal member is connected in contact with the inner wall side surface of the current collecting member. The upper or lower surface of the fuel cell is not fixedly connected to the top or bottom surface of the current collecting member facing the upper or lower surface.
Since the foil-like metal member is planar, it has a smaller cross-sectional area and higher electrical resistance than other shapes. For this reason, when the end portion of the metal member is connected to the fuel cell and the current collecting member, the electrical resistance increases at the end portion. On the other hand, according to the present invention having the above-described configuration, the foil-like metal member can be brought into surface contact with both the fuel battery cell and the current collecting member, whereby the electrical resistance at the end can be reduced and bonded. Strength can be improved. In addition, the conductive paste shrinks due to elimination of volatile components during firing, but according to the present invention having the above configuration, the foil-like metal member is in surface contact with the fuel cell and the current collecting member. Can be deformed following the contraction of the film, and a high conductive connection by surface contact can be maintained.

  Moreover, according to this invention of the said structure, since the foil-shaped metal member is in surface contact with the upper surface or lower surface of a fuel cell, and the inner wall side surface of the current collection member surrounding a fuel cell, it is L-shaped. It will be in the state bent by. Since the foil-like metal member becomes L-shaped in this way, the foil-like metal member bends. Therefore, the deflection causes the displacement due to the difference in the thermal expansion coefficient between the fuel cell and the current collecting member. Can be absorbed. In addition, when connecting the fuel cell and the current collecting member, a foil-like metal member is attached to the current collecting member in advance, and the foil-like metal member is inserted by inserting the fuel cell toward the current collecting member. It can be connected to a fuel cell, and assembly work is facilitated.

  In the present invention, preferably, one surface of the foil-shaped metal member is connected to the upper surface or the lower surface of the fuel cell, and the other surface portion of the foil-shaped metal member corresponding to the portion to which the fuel cell is connected A temporary fixing member that temporarily fixes the foil-shaped metal and the top surface or bottom surface of the current collecting member before firing and releases the temporary fixing after firing is provided.

  In order to reduce the variation in the dimensions of the fuel cell, it is preferable that the upper surface or the lower surface of the fuel cell is brought into contact with the top surface or the bottom surface of the current collecting member in the fuel cell manufacturing process. However, after manufacturing the fuel cell, it is necessary that the upper surface or the lower surface of the fuel cell be displaceable with respect to the top surface or the bottom surface of the current collecting member so that the thermal stress can be absorbed.

  On the other hand, according to the present invention having the above-described configuration, the temporary fixing member that temporarily fixes the foil-shaped metal and the top surface or the bottom surface of the current collecting member before firing, and is temporarily released after firing. When the fuel cell is manufactured, the upper surface or the lower surface of the current collecting member is brought into contact with the top surface or the bottom surface of the current collecting member. Alternatively, it can be displaced with respect to the bottom surface.

In the present invention, preferably, one surface of the foil-shaped metal member is connected to the upper surface or the lower surface of the fuel cell by a conductive paste.
The space between the current collecting member and the fuel cell is very narrow. For this reason, even if it is going to connect a foil-shaped metal member and a fuel battery cell by electroconductive brazing, it is very difficult to pour wax from the outside. Furthermore, the expansion coefficient of the wax is larger than that of the surrounding members, and the fuel cell is easily damaged or the foil-like metal member is easily peeled off. On the other hand, according to the present invention having the above configuration, if the conductive paste is attached to the fuel cell in advance, the fuel cell is inserted into the current collecting member, and then the foil-like metal member is easily attached to the fuel cell. Can be connected to a cell. Furthermore, since the conductive paste is porous and itself can be deformed, it is possible to prevent the fuel cell from being damaged and the foil-like metal member from being peeled off.

In the present invention, preferably, the temporary fixing member is made of the same material as the conductive paste for connecting the foil-shaped metal member to the fuel cell, and the conductive paste is more closely attached to the fuel cell than the current collecting member. High nature.
According to the present invention having the above configuration, by using a conductive paste having higher adhesion to the fuel cell than the current collecting member as the temporary fixing member, the thermal stress generated by the shrinkage during sintering of the conductive paste The temporarily fixing member and the current collecting member are peeled off. Thereby, the upper surface or the lower surface of the fuel cell can be displaced with respect to the top surface or the bottom surface of the current collecting member.

In the present invention, the current collecting member preferably has a chromium oxide layer on the inner wall surface.
According to the present invention having the above configuration, since the current collecting member has a chromium oxide layer on the inner wall surface, the adhesion between the temporary fixing member and the current collecting member is weakened, and more easily peels off due to thermal stress during sintering. .

  A solid oxide fuel cell device of the present invention includes the above fuel cell stack, a module case that accommodates the fuel cell stack, and a fuel gas that is disposed in the module case and reforms the raw fuel gas with water vapor. And a reformer for supplying the fuel gas to the fuel cell stack.

  ADVANTAGE OF THE INVENTION According to this invention, the output of the favorable electric power from a fuel cell can be maintained even if exposed to the heat fluctuation by electric power generation reaction.

1 is an overall configuration diagram showing a solid oxide fuel cell apparatus (SOFC) according to a first embodiment of the present invention. It is side surface sectional drawing which shows the fuel cell module of the solid oxide fuel cell apparatus by 1st Embodiment of this invention. It is sectional drawing along the III-III line of FIG. 1 is an exploded perspective view of a module case and an air passage cover of a solid oxide fuel cell device according to a first embodiment of the present invention. 1 is a partial cross-sectional view showing a fuel cell unit of a solid oxide fuel cell according to a first embodiment of the present invention. It is an expanded sectional view of the VI section of Drawing 5, (a) shows the case where a fuel cell has a conductive support as a support, and (b) shows the case where it has an insulating support. It is VII-VII sectional drawing in Fig.6 (a). It is a perspective view which shows the silver foil used by 1st Embodiment. 1 is a perspective view showing a fuel cell stack of a solid oxide fuel cell according to a first embodiment of the present invention. It is front sectional drawing which shows a fuel cell module for demonstrating the flow of the gas in the fuel cell module of the solid oxide fuel cell apparatus by 1st Embodiment of this invention. FIG. 3 is a cross-sectional view of the fuel cell module taken along the line III-III of FIG. 2 for explaining a gas flow in the fuel cell module of the solid oxide fuel cell device according to the first embodiment of the present invention. It is a schematic diagram for demonstrating the assembly method of the fuel cell unit of the solid oxide fuel cell by 1st Embodiment of this invention. It is a perspective view which shows a mode that the lower end of the fuel cell of the solid oxide fuel cell by 1st Embodiment of this invention is inserted in an inner side electrode terminal. It is a figure which shows a mode that the silver paste in the solid oxide fuel cell by 1st Embodiment of this invention is baked. In the solid oxide fuel cell device according to the first embodiment of the present invention, it is a cross-sectional view of the vicinity of the lower end of the fuel cell showing the behavior when operated for a long time. In the solid oxide fuel cell device according to the first embodiment of the present invention, it is a perspective view of the vicinity of the lower end of the fuel cell showing a state where different thermal expansion occurs in the fuel cell depending on the part. It is sectional drawing which expands and shows the upper part of the fuel cell during electric power generation in the solid oxide fuel cell by 1st Embodiment of this invention. It is sectional drawing which shows the connection structure of the fuel cell in the solid oxide form fuel cell of 2nd Embodiment of this invention, and an inner side electrode terminal.

Next, a solid oxide fuel cell device according to a first embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an overall configuration diagram showing a solid oxide fuel cell apparatus (SOFC) according to a first embodiment of the present invention.
As shown in FIG. 1, a solid oxide fuel cell apparatus (SOFC) 1 according to a first embodiment of the present invention includes a fuel cell module 2 and an auxiliary unit 4.

  The fuel cell module 2 includes a housing 6, and a metal module case 8 is built in the housing 6 via a heat insulating material 7. In the power generation chamber 10, which is the lower part of the module case 8, which is a sealed space, a fuel cell that performs a power generation reaction with fuel gas and oxidant gas (hereinafter referred to as “power generation air” or “air” as appropriate). A cell assembly 12 is arranged. The fuel cell assembly 12 includes eight fuel cell stacks 14 (details will be described later with reference to FIG. 6). The fuel cell stack 14 includes 16 fuel cells each including a fuel cell. It is composed of a cell unit 16 (details will be described later with reference to FIG. 5). In this example, the fuel cell assembly 12 has 128 fuel cell units 16. In the fuel cell assembly 12, all of the plurality of fuel cell units 16 are connected in series.

  A combustion chamber 18 as a combustion section is formed above the power generation chamber 10 of the module case 8 of the fuel cell module 2. In this combustion chamber 18, residual fuel gas and residual air that have not been used for the power generation reaction are formed. Burns and generates exhaust gas (in other words, combustion gas). Further, the module case 8 is covered with the heat insulating material 7 to suppress the heat inside the fuel cell module 2 from being diffused to the outside air. Further, a reformer 120 for reforming the fuel gas is disposed above the combustion chamber 18, and the reformer 120 is heated to a temperature at which a reforming reaction can be performed by the combustion heat of the residual gas. Yes.

  Further, an evaporator 140 is provided in the heat insulating material 7 above the module case 8 in the housing 6. The evaporator 140 performs heat exchange between the supplied water and the exhaust gas, thereby evaporating the water to generate water vapor, and a mixed gas (hereinafter referred to as “fuel gas”) of the water vapor and the raw fuel gas. Is supplied to the reformer 120 in the module case 8.

Next, the auxiliary unit 4 stores pure water tank 26 that stores water condensed from moisture contained in the exhaust gas from the fuel cell module 2 and makes it pure water with a filter, and water supplied from the water storage tank. Is provided with a water flow rate adjusting unit 28 (such as a “water pump” driven by a motor). In addition, the auxiliary unit 4 adjusts the flow rate of the fuel gas, the gas shutoff valve 32 for shutting off the fuel supplied from the fuel supply source 30 such as city gas, the desulfurizer 36 for removing sulfur from the fuel gas, A fuel flow adjustment unit 38 (such as a “fuel pump” driven by a motor) and a valve 39 that shuts off fuel gas flowing out from the fuel flow adjustment unit 38 when power is lost. Further, the auxiliary unit 4 includes an electromagnetic valve 42 that shuts off the air supplied from the air supply source 40, a reforming air flow rate adjusting unit 44 that adjusts the air flow rate, and a power generation air flow rate adjusting unit 45 (with a motor). Driven "air blower", etc., a first heater 46 for heating the reforming air supplied to the reformer 120, and a second heater 48 for heating the power generating air supplied to the power generation chamber. I have. The first heater 46 and the second heater 48 are provided in order to efficiently raise the temperature at startup, but may be omitted.
In this embodiment, the partial oxidation reforming reaction (POX) and the steam reforming reaction (SR) are performed from the POX process in which only the partial oxidation reforming reaction (POX) occurs in the reformer 120 when the apparatus is started. The SR process in which only the steam reforming reaction is performed may be performed through the ATR process in which the mixed autothermal reforming reaction (ATR) occurs, or the POX process may be omitted and the ATR process may be changed to the SR process. You may comprise so that it may transfer, and it may comprise so that a POX process and an ATR process may be abbreviate | omitted and only an SR process may be performed. In the configuration in which only the SR step is performed, the reforming air flow rate adjustment unit 44 is unnecessary.

  Next, a hot water production apparatus 50 to which exhaust gas is supplied is connected to the fuel cell module 2. The hot water production apparatus 50 is supplied with tap water from the water supply source 24, and the tap water is heated by the heat of the exhaust gas and supplied to a hot water storage tank of an external hot water heater (not shown). The fuel cell module 2 is provided with a control box 52 for controlling the amount of fuel gas supplied and the like. Furthermore, the fuel cell module 2 is connected to an inverter 54 that is a power extraction unit (power conversion unit) for supplying the power generated by the fuel cell module to the outside.

Next, the structure of the fuel cell module of the solid oxide fuel cell device according to the first embodiment of the present invention will be described with reference to FIGS.
FIG. 2 is a side sectional view showing the fuel cell module of the solid oxide fuel cell device according to the first embodiment of the present invention, and FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 4 is an exploded perspective view of the module case and the air passage cover.

  As shown in FIGS. 2 and 3, the fuel cell module 2 includes a fuel cell assembly 12 and a reformer 120 provided inside a module case 8 covered with a heat insulating material 7, and the module case 8. And an evaporator 140 provided in the heat insulating material 7.

  First, as shown in FIG. 4, the module case 8 includes a substantially rectangular top plate 8a, bottom plate 8c, and a pair of opposing side plates 8b that connect the sides extending in the longitudinal direction (left-right direction in FIG. 2). A cylindrical body and a closed side plate that closes two opposing openings at both ends in the longitudinal direction of the cylindrical body and connects the sides extending in the width direction of the top plate 8a and the bottom plate 8c (left and right direction in FIG. 3) 8d and 8e.

  The module case 8 has a top plate 8 a and side plates 8 b covered with an air passage cover 160. The air passage cover 160 includes a top plate 160a and a pair of opposing side plates 160b. An opening 167 for allowing the exhaust pipe 171 to pass therethrough is provided at a substantially central portion of the top plate 160a. The top plate 160a and the top plate 8a and the side plate 160b and the side plate 8b are separated by a predetermined distance. As a result, there is oxidation between the outside of the module case 8 and the heat insulating material 7, specifically between the top plate 8a and the side plate 8b of the module case 8, and between the top plate 160a and the side plate 160b of the air passage cover 160. Air passages 161a and 161b are formed as agent gas supply passages (see FIG. 3).

  At the lower part of the side plate 8b of the module case 8, a plurality of through holes 8f are provided (see FIG. 4). The power generation air passes through the flow direction adjustment unit 164 from the power generation air introduction pipe 74 provided in the substantially central portion of the top plate 160a of the air passage cover 160 on the closed side plate 8e side of the module case 8. 161a (see FIGS. 2 and 4). Then, the power generation air is injected into the power generation chamber 10 through the air passages 161a and 161b from the outlet 8f toward the fuel cell assembly 12 (see FIGS. 3 and 4).

  Further, plate fins 162 and 163 as heat exchange promoting members are provided inside the air passages 161a and 161b (see FIG. 3). The plate fins 162 are provided in the horizontal direction so as to extend in the longitudinal direction and the width direction between the top plate 8a of the module case 8 and the top plate 160a of the air passage cover 160, and the plate fins 163 are the side plates 8b of the module case 8. And the side plate 160b of the air passage cover 160 and at a position above the fuel cell unit 16 so as to extend in the longitudinal direction and the vertical direction.

  The power generation air flowing through the air passages 161a and 161b is inside the module case 8 inside the plate fins 162 and 163 (specifically along the top plate 8a and the side plate 8b), particularly when passing through the plate fins 162 and 163. Heat exchange is performed with the exhaust gas passing through the exhaust passage). For this reason, the portions where the plate fins 162 and 163 are provided in the air passages 161a and 161b function as a heat exchanger (heat exchange section). The portion provided with the plate fins 162 constitutes a main heat exchanger portion, and the portion provided with the plate fins 163 constitutes a subordinate heat exchanger portion.

  Next, the evaporator 140 is fixed on the top plate 8a of the module case 8 so as to extend in the horizontal direction. Further, a portion 7a of the heat insulating material 7 is disposed between the evaporator 140 and the module case 8 so as to fill these gaps (see FIGS. 2 and 3).

  Specifically, the evaporator 140 includes a fuel supply pipe 63 that supplies water and raw fuel gas (which may include reforming air) to one side end side in the longitudinal direction (left-right direction in FIG. 2). The exhaust gas exhaust pipe 82 (see FIG. 3) for exhaust gas exhaust is connected, and the upper end of the exhaust pipe 171 is connected to the other side end in the longitudinal direction. The exhaust pipe 171 extends downward through an opening 167 formed in the top plate 160 a of the air passage cover 160, and is connected to an exhaust port 111 formed on the top plate 8 a of the module case 8. The exhaust port 111 is an opening through which the exhaust gas generated in the combustion chamber 18 in the module case 8 is discharged to the outside of the module case 8, and is substantially at the center of the top plate 8 a that is substantially rectangular in top view. Is formed.

  In addition, as shown in FIGS. 2 and 3, the evaporator 140 has an evaporator case 141 that is substantially rectangular in top view. The evaporator case 141 is formed by joining two low-profile bottomed rectangular cylindrical upper case 142 and lower case 143 with an intermediate plate 144 sandwiched therebetween.

  Accordingly, the evaporator case 141 has a two-layer structure in the vertical direction, and an exhaust passage portion 140A through which the exhaust gas supplied from the exhaust pipe 171 passes is formed in the lower layer portion, and a fuel layer is formed in the upper layer portion. An evaporation unit 140B that evaporates water supplied from the supply pipe 63 to generate water vapor, and a mixing unit 140C that mixes the water vapor generated in the evaporation unit 140B and the raw fuel gas supplied from the fuel supply pipe 63 are provided. It has been.

As shown in FIGS. 2 and 3, the evaporator 140B and the mixer 140C are formed in a space in which the evaporator 140 is partitioned by a partition plate 145 having a plurality of communication holes (slits) 145a. The evaporation unit 140B is filled with alumina balls (not shown).
Similarly, the exhaust passage portion 140A is partitioned into three spaces from the upstream side to the downstream side of the exhaust gas by two partition plates 146 and 147 having a plurality of communication holes. The second space is filled with a combustion catalyst (not shown). That is, the evaporator 140 of this embodiment includes a combustion catalyst in the lower layer structure of the two-layer structure in the vertical direction.

  In such an evaporator 140, heat exchange is performed between the water in the evaporation section 140B and the exhaust gas passing through the exhaust passage section 140A, and the water in the evaporation section 140B is evaporated by the heat of the exhaust gas, Water vapor will be generated. Further, heat exchange is performed between the mixed gas in the mixing section 140C and the exhaust gas passing through the exhaust passage section 140A, and the temperature of the mixed gas is raised by the heat of the exhaust gas.

  Further, as shown in FIG. 2, a mixed gas supply pipe 112 for supplying a mixed gas to the reformer 120 is connected to the mixing unit 140C. The mixed gas supply pipe 112 is disposed so as to pass through the inside of the exhaust pipe 171, one end is connected to an opening 144 a formed in the intermediate plate 144, and the other end is formed on the top surface of the reformer 120. Connected to the mixed gas supply port 120a. The mixed gas supply pipe 112 passes through the exhaust passage portion 140A and the exhaust pipe 171 and extends vertically downward into the module case 8, where it is bent approximately 90 ° and extends horizontally along the top plate 8a. , Bent downward by approximately 90 ° and connected to the reformer 120.

  Next, the reformer 120 is disposed above the combustion chamber 18 so as to extend horizontally along the longitudinal direction of the module case 8, and the exhaust gas guiding member 130 is disposed between the top plate 8 a of the module case 8. And fixed to the top plate 8a with a predetermined distance therebetween. The reformer 120 has a substantially rectangular outer shape in a top view, but is an annular structure in which a through hole 120b is formed in the center, and has a casing in which an upper case 121 and a lower case 122 are joined. ing. The through hole 120b is positioned so as to overlap the exhaust port 111 formed in the top plate 8a in a top view, and preferably, the exhaust port 111 is formed at the center position of the through hole 120b.

  On one end side in the longitudinal direction of the reformer 120 (closed side plate 8e side of the module case 8), the mixed gas supply pipe 112 is connected to the mixed gas supply port 120a provided in the upper case 121, and the other end side ( On the closed side plate 8 d side), the fuel gas supply pipe 64 is connected to the lower case 122, and the hydrogen desulfurizer hydrogen extraction pipe 65 extending to the desulfurizer 36 is connected to the upper case 121. Therefore, the reformer 120 receives the mixed gas (that is, raw fuel gas mixed with water vapor (may include reforming air)) from the mixed gas supply pipe 112, reforms the mixed gas therein, The reformed gas (that is, fuel gas) is discharged from the fuel gas supply pipe 64 and the hydrogen extraction pipe 65 for hydrodesulfurizer.

  The reformer 120 is divided into three spaces by the two partition plates 123a and 123b, so that the reformer 120 receives a mixed gas from the mixed gas supply pipe 112 in the reformer 120. And a reforming section 120B filled with a reforming catalyst (not shown) for reforming the mixed gas, and a gas discharge section 120C for discharging the gas that has passed through the reforming section 120B are formed. (See FIG. 2). The reforming unit 120B is a space sandwiched between the partition plates 123a and 123b, and the reforming catalyst is held in this space. The mixed gas and the reformed fuel gas are movable through a plurality of communication holes (slits) provided in the partition plates 123a and 123b. As the reforming catalyst, a catalyst obtained by imparting nickel to the alumina sphere surface or a catalyst obtained by imparting ruthenium to the alumina sphere surface is appropriately used.

The mixed gas supplied from the evaporator 140 through the mixed gas supply pipe 112 is ejected to the mixed gas receiving unit 120A through the mixed gas supply port 120a. The mixed gas is expanded in the mixed gas receiving unit 120A, the jetting speed is reduced, and is supplied to the reforming unit 120B through the partition plate 123a.
In the reforming unit 120B, the mixed gas moving at a low speed is reformed into a fuel gas by the reforming catalyst, and the fuel gas passes through the partition plate 123b and is supplied to the gas discharge unit 120C.
In the gas discharge unit 120C, the fuel gas is discharged to the fuel gas supply pipe 64 and the hydrogen extraction pipe 65 for the hydrodesulfurizer.

  A fuel gas supply pipe 64 as a fuel gas supply passage extends downward in the module case 8 along the closed side plate 8d, is bent approximately 90 ° in the vicinity of the bottom plate 8c, and extends in the horizontal direction. It extends into the manifold 66 formed below the inner side, and further extends horizontally in the manifold 66 to the vicinity of the closed side plate 8e on the opposite side. A plurality of fuel supply holes 64 b are formed in the lower surface of the horizontal portion 64 a of the fuel gas supply pipe 64, and fuel gas is supplied into the manifold 66 from the fuel supply holes 64 b. A lower support plate 68 having a through hole for supporting the fuel cell stack 14 is attached above the manifold 66, and the fuel gas in the manifold 66 is supplied into the fuel cell unit 16. The An ignition device 83 for starting combustion of fuel gas and air is provided in the combustion chamber 18.

  The exhaust gas guiding member 130 is disposed between the reformer 120 and the top plate 8 a so as to extend in the horizontal direction along the longitudinal direction of the module case 8. The exhaust gas guiding member 130 includes a lower guiding plate 131 and an upper guiding plate 132 that are separated by a predetermined distance in the vertical direction, and connecting plates 133 and 134 to which both ends of the longitudinal direction are attached (FIG. 2). FIG. 3). The upper guide plate 132 is bent at both ends in the width direction downward and is connected to the lower guide plate 131. The connecting plates 133 and 134 have upper ends connected to the top plate 8a and lower ends connected to the reformer 120, thereby fixing the exhaust gas guiding member 130 and the reformer 120 to the top plate 8a. ing.

  The lower guide plate 131 is formed with a convex step portion 131a in which the central portion in the width direction (left-right direction in FIG. 3) protrudes downward. On the other hand, as with the lower guide plate 131, the upper guide plate 132 is formed with a recess 132a so that the central portion in the width direction becomes concave downward. The convex step portion 131a and the concave portion 132a extend in the longitudinal direction in parallel in the vertical direction. The mixed gas supply pipe 112 extends horizontally in the recess 132a in the module case 8 and then bends downward in the vicinity of the closed side plate 8e, penetrates the upper guide plate 132 and the lower guide plate 131, It is connected to the reformer 120.

  In the exhaust gas guiding member 130, a gas reservoir 135, which is an internal space that functions as a heat insulating layer, is formed by the upper guiding plate 132, the lower guiding plate 131, and the connecting plates 133 and 134. The gas reservoir 135 is in fluid communication with the combustion chamber 18. That is, the upper guide plate 132, the lower guide plate 131, and the connecting plates 133 and 134 are connected so as to form a predetermined gap, and are not airtightly connected. While it is possible for exhaust gas to flow into the gas reservoir 135 from the combustion chamber 18 during operation, or to allow air to flow in from the outside when stopped, the movement of gas between the inside and outside of the gas reservoir 135 is generally performed. Is moderate.

  The upper guide plate 132 is disposed at a predetermined vertical distance from the top plate 8a, and the exhaust extending in the horizontal direction along the longitudinal direction and the width direction is provided between the upper guide plate 132 and the top plate 8a. A passage 172 is formed. The exhaust passage 172 is arranged in parallel with the air passage 161a with the top plate 8a of the module case 8 interposed therebetween. Inside the exhaust passage 172, plate fins similar to the plate fins 162 and 163 in the air passages 161a and 161b are provided. 175 is arranged. The plate fins 175 are provided at substantially the same location as the plate fins 162 when viewed from above, and face each other in the vertical direction across the top plate 8a. Of the air passage 161a and the exhaust passage 172, in the portion where the plate fins 162 and 175 are provided, efficient heat exchange is performed between the power generation air flowing through the air passage 161a and the exhaust gas flowing through the exhaust passage 172. Thus, the temperature of the power generation air is raised by the heat of the exhaust gas.

  The reformer 120 is disposed at a predetermined horizontal distance from the side plate 8b of the module case 8, and the exhaust gas passes between the reformer 120 and the side plate 8b from below to above. An exhaust passage 173 is formed. Further, the exhaust gas guiding member 130 is also disposed at a predetermined horizontal distance from the side plate 8b, and the exhaust passage 173 includes the passage between the exhaust gas guiding member 130 and the side plate 8b and extends to the top plate 8a. ing. The exhaust passage 173 communicates with the exhaust passage 172 through an exhaust gas introduction port 172a located at the corner between the top plate 8a and the side plate 8b. The exhaust gas introduction port 172a extends in the longitudinal direction in the module case 8.

  Further, the lower guide plate 131 is disposed at a predetermined vertical distance from the top surface of the upper case 121 of the reformer 120, and between the lower guide plate 131 and the upper case 121 and the reformer. The through hole 120b of 120 forms an exhaust passage 174 through which the exhaust gas that has passed through the through hole 120b from the lower side to the upper side is passed. The exhaust passage 174 joins the exhaust passage 173 above the reformer 120.

Next, the fuel cell unit 16 will be described with reference to FIGS.
FIG. 5 is a partial cross-sectional view showing the fuel cell unit of the solid oxide fuel cell according to the first embodiment of the present invention. FIG. 6 is an enlarged cross-sectional view of a VI part in FIG. 5, (a) shows a case where the fuel cell has a conductive support as a support, and (b) shows a case where an insulating support is provided. FIG. 7 is a sectional view taken along line VII-VII in FIG.
As shown in FIG. 5, the fuel cell unit 16 includes a fuel cell 84 and inner electrode terminals 86 that are caps respectively connected to both ends of the fuel cell 84.

  As shown in FIGS. 5 and 6A, the fuel cell 84 having a conductive support as a support is a tubular structure extending in the vertical direction, and a cylinder that forms a fuel gas flow path 88 therein. Conductive support 189, a substantially cylindrical inner electrode layer 90 provided on the outer periphery of conductive support 189, a cylindrical electrolyte layer 94 provided on the outer periphery of inner electrode layer 90, and electrolyte layer 94 A cylindrical outer electrode layer 92 provided on the outer periphery. 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.

The conductive support 189 is made of a porous conductor such as Ni / YSG, for example, and the fuel gas passing through the fuel gas flow path 88 contacts the inner electrode layer 90 through the conductive support 189.
As shown in FIG. 6A, the inner electrode layer 90 is formed over the entire circumference along the outer peripheral surface of the conductive support 189. When the conductive support 189 is provided as the support, the inner electrode layer 90 can be made of GDC, for example.

  Further, as shown in FIG. 6B, the fuel cell 84 in the case of having an insulating support as a support does not include the conductive support 189, but instead has an insulating support 89. The insulating support 89 is cylindrical and has a fuel gas flow path 88 formed therein. The insulating support 89 is made of a porous insulator, and the fuel gas passing through the fuel gas flow path 88 contacts the inner electrode layer 90 through the insulating support 89.

As shown in FIG. 6B, when the insulating support 89 is provided as the support, the inner electrode layer 90 is formed over the entire circumference along the outer peripheral surface of the insulating support 89, and further, the insulating support is provided. The upper and lower surfaces of the body 89 are covered. 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. In the present embodiment, the inner electrode layer 90 is made of Ni / YSZ.
Note that the other configurations are the same whether the conductive support 189 is used as the support or the insulating support 89 is used.

  The electrolyte layer 94 is formed over the entire circumference along the outer peripheral surface of the inner electrode layer 90, the lower end is terminated above the lower end of the inner electrode layer 90, and the upper end is below the upper end of the inner electrode layer 90. It is terminated. 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 is formed over the entire circumference along the outer peripheral surface of the electrolyte layer 94, and the lower end terminates above the lower end of the electrolyte layer 94, and the upper end terminates below the upper end of the electrolyte layer 94. ing. 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 inner electrode terminal 86 will be described. Since the inner electrode terminals 86 attached to the upper end side and the lower end side of the fuel cell 84 have the same structure, they are attached to the lower end side of the fuel cell 84 here. The inner electrode terminal 86 formed will be specifically described.

  The inner electrode terminal 86 is provided so as to surround the upper and lower ends of the fuel battery cell 84, and functions as a current collecting member for taking out the electric power generated by the fuel battery cell 84 from the fuel battery cell 84. As shown in FIG. 6, the inner electrode terminal 86 provided at the lower end of the fuel cell 84 has a cylindrical first cylindrical portion 86a and an annular shape extending outward from the upper end of the first cylindrical portion 86a. And the second cylindrical portion 86c extending upward from the outer periphery of the annular portion 86b. 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 first cylindrical portion 86 a of the inner electrode terminal 86.

The inner electrode terminal 86 includes an electrode layer body 86A made of ferritic stainless steel or austenitic stainless steel. The inner and outer peripheral surfaces of the electrode layer main body 86A are coated with Cr ₂ O ₃ layers 86B and 86C coated with chromium oxide (Cr ₂ O _{3 in} this embodiment). Further, on the outer peripheral surface of the outer Cr ₂ O ₃ layer 86C, MnCo ₂ O ₄ is formed by coating MnCo ₂ O ₄ layer 86D are laminated. Further, an Ag current collecting film 86E is provided on the outer peripheral surface of the MnCo ₂ O ₄ layer 86D. In the present embodiment, the Ag current collector film 86E includes the first cylindrical portion 86a, the annular portion 86b, and the second cylindrical portion 86c over the entire outer peripheral surface, but may be provided only in part.

  The fuel gas flow path 98 is an elongated pipe line provided to extend in the axial direction of the fuel cell 84 from the center of the inner electrode terminal 86. Therefore, a predetermined pressure loss occurs in the flow of the fuel gas flowing from the manifold 66 (see FIG. 2) through the fuel gas passage 98 of the lower inner electrode terminal 86 into the fuel gas passage 88. . Therefore, the fuel gas flow path 98 of the lower inner electrode terminal 86 acts as an inflow side flow path resistance portion, and the flow path resistance is set to a predetermined value. Further, a predetermined pressure loss also occurs in the flow of the fuel gas flowing out from the fuel gas flow path 88 to the combustion chamber 18 (see FIG. 2) through the fuel gas flow path 98 of the upper inner electrode terminal 86. Therefore, the fuel gas flow path 98 of the upper inner electrode terminal 86 functions as an outflow-side flow path resistance portion, and the flow path resistance is set to a predetermined value.

  The upper surface (bottom surface) of the annular portion 86b of the inner electrode terminal 86 is separated from the lower surface of the inner electrode layer 90 of the fuel cell 84, and a space is provided between these surfaces. An annular space is provided between the second cylindrical portion 86 c of the inner electrode terminal 86 and the outer peripheral surface of the lower end portion of the inner electrode layer 90. A silver foil 91, which will be described in detail later, is disposed in these spaces so as to be deformable. As shown in FIG. 6, a glass seal 96 made of a glass material is provided between the outer peripheral surface of the lower end portion of the electrolyte layer 94 of the inner electrode layer 90 and the inner peripheral surface of the second cylindrical portion 86 c of the inner electrode terminal 86. Is provided. With this glass seal 96, the space between the inner electrode terminal 86 and the inner electrode layer 90 is hermetically sealed with respect to the space outside the fuel cell unit 16. In this way, the upper surface of the annular portion 86b of the inner electrode terminal 86 and the lower surface of the inner electrode layer 90 facing the upper surface of the annular portion 86b are separated from each other, and the inner electrode terminal 86 and the inner electrode layer 90 are separated. Is not fixedly connected.

  The fuel cell 84 is electrically connected to the inner electrode terminal 86 by a flexible foil-shaped silver foil 91. As the silver foil 91, for example, a silver foil having a thickness of about 50 μm is used. FIG. 8 is a perspective view showing a silver foil used in the first embodiment. As shown in the figure, the silver foil 91 has an annular ring part 91A and a plurality of band-like parts 91B that are bent from the outer periphery of the annular part 91A and extend obliquely upward. A plurality of cuts 91D extending radially upward are formed between the plurality of strips 91B, and the plurality of strips 91B are separated in the circumferential direction by the cuts 91D. Each notch 91 </ b> D reaches the upper end of the silver foil 91. In the silver foil 91, an annular ring portion 91A is located in a cylindrical space between the lower surface of the fuel cell 84 and the upper surface of the inner electrode terminal 86, and the plurality of strip portions 91B are formed of the fuel cell. It is located over the entire circumference in an annular space between the outer peripheral surface of the cell 84 and the inner peripheral surface of the inner electrode terminal 86. As will be described later, since the plurality of cuts 91D are formed in the silver foil 91, even if different stresses are generated in the fuel cell 84 or the inner electrode terminal 86 depending on the part, each of the strips 91B is subjected to stress. You can follow them accordingly. That is, the notch 91D functions as a local stress follower that follows in accordance with the stress generated in each portion when a different stress is generated in at least one of the fuel cell 84 and the inner electrode terminal 86 depending on the portion. In the present embodiment, the cuts 91D are formed only at the end of the silver foil 91 that is connected to the inner electrode terminal 86, but the present invention is not limited to this, and the end of the silver foil 91 that is connected to the fuel cell 84 is also formed. A cut may be formed, and a cut may be formed at both ends.

  As shown in FIG. 6, the annular portion 91 </ b> A of the silver foil 91 is attached in surface contact with a portion other than the fuel gas channel 88 on the lower surface of the inner electrode layer 90 of the fuel cell 84 by the first silver paste 93 </ b> A. It has been. The first silver paste 93 </ b> A adheres the silver foil 91 to the inner electrode layer 90 by baking a conductive paste containing silver (Ag), palladium (Pd), and nickel (Ni).

  Further, the belt-like portion 91B of the silver foil 91 is attached in a state of surface contact with the inner peripheral surface of the second cylindrical portion 86c of the inner electrode terminal 86 by the second silver paste 93B. As shown in FIG. 7, the second silver paste 93 </ b> B is provided over the entire length in the vertical direction of the strip portion 91 </ b> B along the edge adjacent to the notch 91 </ b> D of the strip portion 91 </ b> B of the silver foil 91. And the strip-shaped part 91B is not provided in the other site | part, ie, the area | region between the edges adjacent to the notch | incision 91D of the strip-shaped part 91B, ie, a horizontal direction center area | region. The second silver paste 93B bonds the silver foil 91 to the inner electrode terminal 86 by firing a conductive paste containing silver (Ag) and palladium (Pd). As shown in FIG. 6, the region of the silver foil 91 connected to the fuel cell 84 and the region connected to the inner electrode terminal 86 are separated.

  The silver foil 91 has a bent portion 91 </ b> C and is accommodated in the space between the inner electrode terminal 86 and the fuel cell 84 in a state bent at the bent portion. Specifically, the silver foil 91 extends downward from a portion connected to the inner electrode terminal 86 via the second silver paste 93B in a vertical sectional view, and is bent at a substantially right angle toward the inner side at the bent portion 91C. The portion extending inwardly is connected to the lower surface of the fuel cell 84 via the first silver paste 93A. The bent portion 91C has a curvature, and the silver foil 91 is in a curved state. Thus, the silver foil 91 is held in a bent state between the inner electrode terminal 86 and the fuel cell 84 by having the bent portion 91C. Thereby, as will be described later, the silver foil 91 can be deformed following the stress applied to the fuel cell 84.

Next, the fuel cell stack 14 will be described with reference to FIG.
FIG. 9 is a perspective view showing the fuel cell stack of the solid oxide fuel cell according to the first embodiment of the present invention.
As shown in FIG. 9, the fuel cell stack 14 includes 16 fuel cell units 16, and these fuel cell units 16 are arranged in two rows of 8 each.
Each fuel cell unit 16 is supported by a rectangular lower support plate 68 made of ceramic (see FIG. 2) on the lower end side, and on the upper end side, two fuel cell unit units 16 at both ends are provided, each having a substantially square shape. Is supported by the upper support plate 100. The lower support plate 68 and the upper support plate 100 are formed with through holes through which the inner electrode terminal 86 can pass.

  Furthermore, a current collector 102 and an external terminal 104 are attached to the fuel cell unit 16. The current collector 102 includes a fuel electrode connection portion 102a that is electrically connected to an inner electrode terminal 86 attached to the inner electrode layer 90 that is a fuel electrode, and an outer peripheral surface of the outer electrode layer 92 that is an air electrode. It is integrally formed so as to connect the air electrode connecting portion 102b that is electrically connected. In addition, a silver thin film is formed on the entire outer surface of the outer electrode layer 92 (air electrode) of each fuel cell unit 16 as an electrode on the air electrode side. When the air electrode connecting portion 102b contacts the surface of the thin film, the current collector 102 is electrically connected to the entire air electrode.

  Furthermore, two external terminals 104 are connected to the air electrode of the fuel cell unit 16 located at the end of the fuel cell stack 14 (the far left side in FIG. 9). These external terminals 104 are connected to the inner electrode terminal 86 of the fuel cell unit 16 at the end of the adjacent fuel cell stack 14, and as described above, all 128 fuel cell units 16 are connected in series. It has come to be.

Next, a gas flow in the fuel cell module of the solid oxide fuel cell device according to the first embodiment of the present invention will be described with reference to FIGS.
FIG. 10 is a side sectional view showing the fuel cell module of the solid oxide fuel cell device according to the first embodiment of the present invention, similar to FIG. 2, and FIG. 11 is similar to FIG. It is sectional drawing along the III-III line.
10 and 11 are diagrams in which arrows indicating gas flow are newly added in FIGS. 2 and 3, respectively, and for the sake of convenience of explanation, a state in which the heat insulating material 7 is removed is illustrated. . In the figure, solid line arrows indicate the flow of fuel gas, broken line arrows indicate the flow of power generation air, and alternate long and short dashed arrows indicate the flow of exhaust gas.

  As shown in FIG. 10, water and raw fuel gas (fuel gas) are fed into an evaporation section 140 </ b> B provided in an upper layer of the evaporator 140 from a fuel supply pipe 63 connected to one end side in the longitudinal direction of the evaporator 140. Supplied. The water supplied to the evaporation section 140B is heated by the exhaust gas flowing through the exhaust passage section 140A provided in the lower layer of the evaporator 140 to become water vapor. The water vapor and the raw fuel gas supplied from the fuel supply pipe 63 flow downstream in the evaporation unit 140B and are mixed in the mixing unit 140C. The mixed gas in the mixing section 140C is heated by the exhaust gas flowing through the lower exhaust passage section 140A.

  The mixed gas (fuel gas) formed in the mixing unit 140C is supplied to the reformer 120 in the module case 8 through the mixed gas supply pipe 112. Since the mixed gas supply pipe 112 passes through the exhaust passage portion 140A, the exhaust pipe 171, and the exhaust passage 172 in order, the mixed gas in the mixed gas supply pipe 112 is further heated by the exhaust gas flowing through these passages. The

  The mixed gas flows into the mixed gas receiving part 120A in the reformer 120, and from here passes through the partition plate 123a and flows into the reforming part 120B. The mixed gas is reformed in the reforming unit 120B to become fuel gas. The fuel gas thus generated passes through the partition plate 123b and flows into the gas discharge part 120C.

  Further, the fuel gas branches from the gas discharge part 120 </ b> C into the fuel gas supply pipe 64 and the hydrodesulfurizer hydrogen extraction pipe 65. The fuel gas that has flowed into the fuel gas supply pipe 64 is supplied into the manifold 66 from the fuel supply hole 64 b provided in the horizontal portion 64 a of the fuel gas supply pipe 64, and from the manifold 66 into each fuel cell unit 16. Supplied.

  Further, as shown in FIGS. 10 and 11, the power generation air is supplied from the power generation air introduction pipe 74 to the air passage 161a. When the power generation air passes through the plate fins 162 and 163 in the air passages 161a and 161b, the exhaust air passes through the exhaust passages 172 and 173 formed in the module case 8 below the plate fins 162 and 163. An efficient heat exchange with the gas is performed and the gas is heated. In particular, since the plate fins 175 are provided in the exhaust passage 172 corresponding to the plate fins 162 of the air passage 161a, the power generation air is discharged from the exhaust gas via the plate fins 162 and the plate fins 175. Perform more efficient heat exchange. Thereafter, the power generation air is injected into the power generation chamber 10 from the plurality of air outlets 8 f provided at the lower portion of the side plate 8 b of the module case 8 toward the fuel cell assembly 12.

  In the present embodiment, since the exhaust passage is not formed in the side portion of the fuel cell assembly 12, heat exchange between the power generation air and the exhaust gas is suppressed in this portion. Therefore, in the side portion of the fuel cell assembly 12, it is difficult for the temperature gradient in the vertical direction to occur in the power generation air in the air passage 161b.

  Further, as shown in FIG. 11, the fuel gas not used for power generation in the power generation chamber 10 is combusted in the combustion chamber 18 to become exhaust gas (combustion gas), and rises in the module case 8. Specifically, the exhaust gas branches into an exhaust passage 173 and an exhaust passage 174, between the outer surface of the reformer 120 and the side plate 8 b of the module case 8, and through holes 120 b of the reformer 120. From between the reformer 120 and the exhaust gas guiding member 130. At this time, the exhaust gas passing through the exhaust passage 174 is bisected in the width direction by the convex step portion 131a disposed above the through-hole 120b of the reformer 120, and does not stay at the lower portion of the exhaust gas guiding member 130. The gas is guided toward the exhaust passage 173 and is quickly joined to the exhaust gas flowing through the exhaust passage 173.

Thereafter, the exhaust gas flows into the exhaust passage 172 from the exhaust gas inlet 172a. In the exhaust passage 172, the exhaust gas flows in the horizontal direction in the exhaust passage 172 and flows out from the exhaust port 111 formed in the center of the top plate 8 a of the module case 8.
When the exhaust gas flows upward in the exhaust passage 173, heat exchange is performed between the power generation air and the exhaust gas via the plate fins 163 provided in the air passage 161b. Further, when the exhaust gas flows in the horizontal direction through the exhaust passage 172, a plate fin 175 provided in the exhaust passage 172 and a plate fin 162 provided in the air passage 161a corresponding to the plate fin 175. Thus, efficient heat exchange is performed between the power generation air and the exhaust gas. In this way, the temperature of the power generation air is raised by the heat of the exhaust gas.

  The exhaust gas flowing out from the exhaust port 111 passes through the exhaust pipe 171 provided outside the module case 8, flows into the exhaust passage part 140A of the evaporator 140, passes through the exhaust passage part 140A, and then evaporates. From the vessel 140 to the exhaust gas discharge pipe 82. As described above, the exhaust gas exchanges heat with the mixed gas in the mixing section 140C of the evaporator 140 and the water in the evaporation section 140B when flowing through the exhaust passage section 140A of the evaporator 140.

  Here, a method for assembling the fuel cell unit 16 will be described. FIG. 12 is a schematic view for explaining an assembly method of the fuel cell unit 16. In the following description, the case where the inner electrode terminal 86 is attached to the lower end of the fuel cell 84 will be described, but the same can be done when the inner electrode terminal 86 is attached to the upper end of the fuel cell.

  First, as shown in FIG. 12 (A1), a fuel cell 84 is prepared. As shown in (A2), the first silver paste 93A is applied to the lower surface and the upper surface of the inner electrode layer 90 of the fuel cell 84. Adhere in a ring.

Further, as shown in FIG. 12 (B1), the inner electrode terminal 86 is prepared, and as shown in (B2), the inner surface of the second cylindrical portion 86c and the inner surface of the annular portion 86b of the inner electrode terminal 86 are respectively provided. A second silver paste 93B and a third silver paste 93C are attached. The third silver paste 93 </ b> C is made of the same material as the first silver paste 93 </ b> A for attaching the silver foil 91 to the fuel cell 84. Since the first and third silver pastes 93A and 93C are mixed with nickel, the adhesion of the fuel cell 84 made of a material containing nickel to the inner electrode layer 90 has a Cr of the inner electrode terminal 86 that does not contain nickel. _It is larger than the adhesion force to the ₂ O ₃ layer 86B. When the silver foil 91 is fitted, the second silver paste 93B is attached so as to extend in the vertical direction at a location where the cut 91D of the silver foil 91 is located.

  Further, as shown in FIG. 12 (C1), a flat silver foil 91 is prepared. The flat silver foil 91 has a shape in which a plurality of strip-shaped portions 91B extend radially from the outer peripheral portion of an annular ring portion 91A. And as shown in the figure (C2), the base of the strip | belt-shaped part 91B is bend | folded. At this time, the base of the belt-like portion 91B is bent so as to be bent with a curvature.

  Next, as shown in FIG. 12D, the silver foil 91 is disposed inside the inner electrode terminal 86. Then, the lower surface of the annular portion 91A of the silver foil 91 is attached to the third silver paste 93C, and the belt-like portion 91B of the silver foil 91 is attached to the second silver paste 93B. Thereby, the silver foil 91 is fixed to the inner electrode terminal 86. At this time, the silver foil 91 is arranged so that the vicinity of the edge facing the notch 91D of the strip 91B of the silver foil 91 adheres to the second silver paste 93B. At this time, the second silver paste 93B may leak from the notch 91D of the silver foil 91 to the inside of the strip portion 91B, but the inner wall of the second cylindrical portion 86c of the inner electrode terminal 86 and the outer surface of the fuel cell 84 Since there is a gap between them, the fuel cell 84 does not adhere. As will be described later, the third silver paste 93C is peeled off from the upper surface (top surface) of the inner electrode terminal 86 during firing. For this reason, the third silver paste 93 </ b> C functions as a temporary fixing member for temporarily fixing the silver foil and the top surface of the inner electrode terminal 86.

  Next, as shown in FIG. 12E, the lower end of the fuel cell 84 is inserted into the inner electrode terminal 86. FIG. 13 is a perspective view showing a state where the lower end of the fuel battery cell is inserted into the inner electrode terminal. As shown in FIG. 13, when the lower end of the fuel battery cell 84 is inserted into the inner electrode terminal 86, the lower end of the fuel battery cell 84 comes into contact with the belt-like portion 91 </ b> B of the silver foil 91. Then, when the fuel cell 84 is further pushed in this state, a force is applied to the fuel cell 84 from the band portions 91B toward the center by the elastic force of the band portions 91B. In this way, a force that goes from the entire circumference toward the center acts on the fuel cell 84, so that the fuel cell 84 is pushed so that its central axis coincides with the central axis of the inner electrode terminal 86. Thereby, the fuel cell 84 and the inner electrode terminal 86 can be easily arranged coaxially. Then, by inserting the lower end of the fuel cell 84 into the inner electrode terminal 86, the lower surface of the first silver paste 93 </ b> A attached to the lower surface of the fuel cell 84 adheres to the upper surface of the annular portion 91 </ b> A of the silver foil 91. To do.

Next, the first silver paste 93A, the second silver paste 93B, and the third silver paste 93C are baked. FIG. 14 is a diagram showing how the silver paste is fired. By baking the silver pastes 93A, 93B, and 93C, the silver pastes 93A, 93B, and 93C shrink to become porous bodies. Thereby, the first silver paste 93 </ b> A fixes the silver foil 91 to the fuel cell 84, and the second silver paste 93 </ b> B fixes the silver foil 91 to the inner electrode terminal 86. On the other hand, the first and third silver pastes 93A and 93C have a greater adhesion force to the inner electrode layer 90 of the fuel cell 84 than the adhesion force of the inner electrode terminal 86 to the Cr ₂ O ₃ layer 86B. For this reason, as shown in FIG. 14, when the silver pastes 93A, 93B, and 93C shrink by firing, the first silver paste 93A maintains the connection with the fuel cell 84 and the silver foil 91. No. 3 silver paste 93 </ b> C peels from the inner electrode terminal 86.

  In the solid oxide fuel cell device as described above, the fuel cell 84, the inner electrode terminal 86, and the like are exposed to a high temperature of 700 ° C. or higher. As described above, when the fuel cell 84, the inner electrode terminal 86, and the like are exposed to a high temperature, thermal stress (thermal expansion) is generated in these members. Furthermore, when the first silver paste 93A and the second silver paste 93B are operated for a long time, the particles are sintered and aggregated, and thus contract.

  FIG. 15 is a cross-sectional view of the vicinity of the lower end of the fuel cell showing the behavior when operated for a long time in the solid oxide fuel cell device of the first embodiment. As shown in the figure, when the solid oxide fuel cell device is operated for a long time, the first silver paste 93A and the second silver paste 93B contract as shown by arrows in the figure. At this time, since the first silver paste 93A and the second silver paste 93B are in surface contact with the silver foil 91, the fuel cell 84, and the inner electrode terminal 86, the thickness mainly decreases. Further, the fuel cell 84 and the inner electrode terminal 86 are exposed to a high temperature during operation of the solid oxide fuel cell device. At this time, since the members do not have the same coefficient of thermal expansion, thermal deformation (thermal stress) occurs between the members. In particular, the conductive silver pastes 93A and 93B for attaching the silver foil 91 to the fuel cell 84 and the inner electrode terminal 86 are different in thermal expansion coefficient from other members, so that they are likely to be thermally deformed when exposed to high temperatures. .

  On the other hand, according to this embodiment, since the fuel cell 84 and the inner electrode terminal 86 are connected in a state where the silver foil 91 is bent, the first silver paste 93A and the second silver paste 93A and the second silver paste 93A are connected. The silver foil 91 can absorb the displacement due to the shrinkage of the paste 93B and the displacement between the members due to the difference in thermal expansion coefficient (for example, the displacement between the fuel cell 84 and the inner electrode terminal 86). Further, according to the present embodiment, since the gap is provided between the fuel cell 84 and the inner electrode terminal 86, this gap absorbs the difference in thermal expansion between the fuel cell 84 and the inner electrode terminal 86. Therefore, it is possible to prevent excessive thermal stress from being generated in the fuel cell 84 and the inner electrode terminal 86.

  In addition, the fuel cell 84 may have different thermal expansion (thermal stress) depending on the part due to uneven temperature. FIG. 16 is a perspective view of the vicinity of the lower end of the fuel battery cell showing a state in which different thermal expansion occurs in the fuel battery cell depending on the part. In FIG. 16, the magnitude of thermal expansion for each part is indicated by the length of the arrow. In the present embodiment, the notch 91D is formed so as to reach the edge of the silver foil 91 on the side attached to the fuel battery cell 84, and is divided into a plurality of belt-like parts 91B. It deforms independently according to the thermal expansion (thermal stress) generated at the attachment position of the cell 84. Thereby, even when different stresses act on the fuel battery cell 84, the silver foil 91 absorbs different thermal expansion (thermal stress) for each part, and damage to the fuel battery cell can be prevented. Further, even when different stresses are generated in the inner electrode terminal 86 depending on the part, the plurality of belt-like portions 91B are independently deformed, and accordingly, different thermal stresses can be absorbed by the silver foil 91 for each part. . Furthermore, as described with reference to FIG. 8, the second silver paste 93 </ b> B is provided only along the edge on the notch 91 </ b> D side of the band-like portion 91 </ b> B. For this reason, the width direction center part of the strip | belt-shaped part 91B can be moved to the radial direction of the fuel cell 84, and can follow a thermal stress more effectively.

  FIG. 17 is an enlarged cross-sectional view showing the upper part of the fuel cell during power generation. As shown in the figure, the remaining fuel gas that has not been used for the power generation reaction in the fuel cell 84 is discharged upward from the fuel gas flow path 98 and burned in the combustion chamber 18 above the fuel cell 84. For this reason, the upper inner electrode terminal 86 is exposed to a high temperature. Here, for example, as described in Patent Document 1, in the configuration in which the fuel battery cell and the inner electrode terminal are connected by a silver sealing material formed by sintering silver solder, the heat of the upper inner electrode terminal is silver. It is directly transmitted to the fuel cell through the sealing material, which causes deterioration of the fuel cell. On the other hand, in the present embodiment, the upper inner electrode terminal 86 and the fuel cell 84 are connected by a silver foil 91 having a lower thermal conductivity than the silver sealing material. For this reason, the heat generated in the combustion chamber 18 is transmitted from the inner electrode terminal 86 to the fuel cell 84 through the silver foil 91 as indicated by the broken line arrow in the figure, and from the upper inner electrode terminal 86. Heat conduction to the fuel cell 84 can be suppressed, and damage to the fuel cell 84 can be prevented.

According to this embodiment, the following effects are produced.
According to the present embodiment, since the fuel cell 84 and the inner electrode terminal 86 are connected in a state where the silver foil 91 is bent, the fuel cell 84 and the inner electrode are caused by a difference in thermal expansion coefficient at a high temperature. Even if a displacement occurs with the terminal 86, it can be absorbed. Furthermore, even if the silver pastes 93A and 93B for attaching the silver foil 91 to the fuel cell 84 and the inner electrode terminal 86 are thermally deformed, the silver foil 91 can be deformed following the heat deformation. For this reason, it is possible to prevent the thermal stress from acting on the fuel cell 84 and to prevent the silver foil 91 from peeling off.

  Here, unless the fuel cell 84 and the inner electrode terminal 86 can be displaced, the metal member cannot sufficiently absorb the thermal stress. However, if an interval is provided between the fuel cell 84 and the inner electrode terminal 86, the gap between the fuel cell 84 and the inner electrode terminal 86 varies among the plurality of fuel cells 84. As a result, variations in dimensions occur between fuel cells.

  In contrast, according to the present embodiment, the silver foil 91 allows the fuel cell 84 to be displaced so that the lower surface (upper surface) of the fuel cell 84 can be displaced with respect to the bottom surface (top surface) of the inner electrode terminal 86. Since it is connected to the inner electrode terminal 86, the thermal stress can be sufficiently absorbed by the silver foil 91. Further, since the lower surface (upper surface) of the fuel cell 84 can be displaced with respect to the bottom surface (top surface) of the inner electrode terminal 86 in this way, the variation in the distance between the fuel cell 84 and the inner electrode terminal 86 is varied. Can be absorbed. In particular, in the manufacturing process of the fuel cell, by bringing the lower surface (upper surface) of the fuel cell 84 into contact with the bottom surface (top surface) of the inner electrode terminal 86, variation in the size of the fuel cell can be reduced.

  In the present embodiment, the silver foil 91 is connected in a state of being in surface contact with the lower surface (upper surface) of the fuel cell 84, and is connected in a state of being in surface contact with the inner wall side surface of the inner electrode terminal 86. The lower surface (upper surface) of 84 is not fixedly connected to the bottom surface (top surface) of the inner electrode terminal 86 facing the lower surface (upper surface). Since the silver foil 91 is planar, it has a smaller cross-sectional area and higher electrical resistance than other shapes. For this reason, when the end of the silver foil 91 is connected to the fuel cell 84 and the inner electrode terminal 86, the electrical resistance increases at the end. On the other hand, according to this embodiment, the silver foil 91 can be brought into surface contact with both the fuel cell 84 and the inner electrode terminal 86, whereby the electrical resistance at the end can be reduced and the adhesive strength can be improved. can do. Further, the silver pastes 93A and 93B shrink due to the removal of volatile components during firing. However, according to the present embodiment, the silver foil 91 is in surface contact with the fuel cell 84 and the inner electrode terminal 86. It can be deformed following the contraction of 93B, and a high conductive connection by surface contact can be maintained.

  Further, according to the present embodiment, the silver foil 91 is in L-shape because it is in surface contact with the lower surface (upper surface) of the fuel cell 84 and the inner wall side surface of the inner electrode terminal 86 surrounding the fuel cell 84. It will be in the bent state. Since the silver foil 91 is bent like this because the silver foil 91 is L-shaped, the deflection caused by the difference in the thermal expansion coefficient between the fuel cell 84 and the inner electrode terminal 86 can be absorbed. it can. Further, when the fuel cell 84 and the inner electrode terminal 86 are connected, the silver foil 91 is attached to the inner electrode terminal 86 in advance, and the fuel cell 84 is inserted toward the inner electrode terminal 86 so that the silver foil 91 is fueled. The battery cell 84 can be connected to facilitate assembly work.

  In the present embodiment, one surface of the silver foil 91 is connected to the lower surface (upper surface) of the fuel cell 84, and the other surface of the silver foil 91 corresponding to the portion to which the fuel cell 84 is connected has a silver foil before firing. A third silver paste 93C is provided as a temporary fixing member that temporarily fixes 91 and the bottom surface (top surface) of the inner electrode terminal 86 and that is temporarily released after firing. In order to reduce the dimensional variation of the fuel cell, it is preferable that the lower surface (upper surface) of the fuel cell 84 is brought into contact with the bottom surface (top surface) of the inner electrode terminal 86 in the manufacturing process of the fuel cell. However, after the fuel cell is manufactured, the lower surface (upper surface) of the fuel cell 84 needs to be displaceable with respect to the bottom surface (top surface) of the inner electrode terminal 86 so that the thermal stress can be absorbed. On the other hand, according to the present embodiment, the third silver paste that temporarily fixes the silver foil 91 and the bottom surface (top surface) of the inner electrode terminal 86 before firing and releases the temporarily fixed after firing. By providing 93C, the lower surface (upper surface) of the fuel cell 84 is brought into contact with the bottom surface (top surface) of the inner electrode terminal 86 during manufacturing, and the lower surface (upper surface) of the fuel cell 84 is manufactured after the fuel cell is manufactured. Can be displaced with respect to the bottom surface (top surface) of the inner electrode terminal 86.

  In the present embodiment, one surface of the silver foil 91 is connected to the upper surface or the lower surface of the fuel cell 84 by the silver paste 93A. The space between the inner electrode terminal 86 and the fuel cell 84 is very narrow. For this reason, even if it is going to connect the silver foil 91 and the fuel battery cell 84 by electroconductive brazing, it is very difficult to pour wax from the outside. Furthermore, the expansion coefficient of the wax is larger than that of the surrounding members, and the fuel cell is easily damaged or the foil-like metal member is easily peeled off. On the other hand, according to the present embodiment, if the silver paste 93A is attached to the fuel cell 84 in advance, the silver foil 91 is easily attached to the fuel cell 84 after the fuel cell 84 is inserted into the inner electrode terminal 86. Can be connected to. Furthermore, since the silver paste 93A is porous and can be deformed itself, the fuel cell 84 can be prevented from being damaged and the foil-like silver foil 91 can be prevented from peeling off.

  In the present embodiment, the third silver paste 93C used as the temporary fixing member is made of the same material as the first silver paste 93A that connects the silver foil 91 to the fuel cell 84, and the silver pastes 93A and 93C are The adhesion to the fuel cell 84 is higher than that of the inner electrode terminal 86. According to the present embodiment as described above, the silver paste 93C having higher adhesion to the fuel cell 84 than the inner electrode terminal 86 is used as the temporary fixing member, and this occurs due to shrinkage during sintering of the silver paste 93C. The silver paste 93C and the inner electrode terminal 86 are peeled off by thermal stress. Thereby, the lower surface (upper surface) of the fuel cell 84 can be displaced with respect to the bottom surface (top surface) of the inner electrode terminal 86.

In the present embodiment, the inner electrode terminal 86 has a Cr ₂ O ₃ layer 86B on the inner wall surface. Thus, since the inner electrode terminal 86 has the Cr ₂ O ₃ layer 86B on the inner wall surface, the adhesion between the third silver paste 93C and the inner electrode terminal 86 is weakened, and is more easily peeled off by thermal stress during sintering. Become.

  In each of the above embodiments, the silver foil 91 is connected to the fuel cell 84 and the inner electrode terminal 86 by the silver paste 93A, 93B, but is not limited thereto, and may be connected by other conductive paste, Further, a conductive brazing material such as silver solder may be used for connection.

  Moreover, in each said embodiment, although silver foil was used as a member for electrically connecting the fuel cell 84 and the inner side electrode terminal 86, it is not restricted to this, The same if it is a foil-shaped metal member. An effect is produced.

  In the first embodiment, the lower surface of the fuel cell 84 and the inner surface of the second cylindrical portion 86c of the inner electrode terminal 86 are connected by the silver foil 91, but the present invention is not limited to this. FIG. 18 is a cross-sectional view showing the connection structure between the fuel cell and the inner electrode terminal in the solid oxide fuel cell according to the second embodiment of the present invention. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. As shown in FIG. 18, also in 2nd Embodiment, the structure and arrangement | positioning of a fuel cell and an inner side electrode terminal are the same as that of 1st Embodiment.

  In the second embodiment, one end portion 191A of the silver foil 191 is connected to the inner surface of the second cylindrical portion 86c of the inner electrode terminal 86 via the second silver paste 93B as in the first embodiment. The silver foil 191 extends downward from one end portion 191A, and is bent inward at the bent portion 191C. The other end 191B of the silver foil 191 is connected to the fuel cell 84 via the first silver paste 193A. Further, it is preferable that one end and / or the other end 191A, 191B of the silver foil 191 is cut into a plurality of strip portions in the same manner as in the first embodiment. Note that the first silver paste 193A of the second embodiment may use the same material as the first silver paste 93A of the first embodiment. Also in the second embodiment having such a configuration, the same effects as in the first embodiment can be obtained.

  In the first and second embodiments, the case where the present invention is applied to a fuel cell device using cylindrical fuel cells has been described. However, the present invention is not limited thereto, and fuel using flat plate fuel cells. The present invention can also be applied to battery devices.

1 Solid oxide fuel cell system (SOFC)
DESCRIPTION OF SYMBOLS 2 Fuel cell module 4 Auxiliary machine unit 6 Housing 7 Heat insulating material 7a Part 8 Module case 8a Top plate 8b Side plate 8c Bottom plate 8d Closed side plate 8d Closed side plate 8f Outlet 10 Power generation chamber 12 Fuel cell assembly 14 Fuel cell stack 16 Fuel Battery cell unit 18 Combustion chamber 24 Water supply source 26 Pure water tank 28 Water flow rate adjustment unit 30 Fuel supply source 32 Gas shutoff valve 36 Desulfurizer 38 Fuel flow rate adjustment unit 39 Valve 40 Air supply source 42 Solenoid valve 44 Reforming air flow rate Adjustment unit 45 Power generation air flow rate adjustment unit 46 Heater 48 Heater 50 Hot water production device 52 Control box 54 Inverter 63 Fuel supply pipe 63a Supply port 64 Fuel gas supply pipe 64a Horizontal portion 64b Fuel supply hole 65 Hydrogen extraction pipe for hydrogenated desulfurizer 66 Maniho De 68 lower support plate 74 generating air inlet tube 82 exhaust gas discharge pipe 83 igniter 84 fuel cell 86 inside electrode terminal 86A electrode layer body 86B Cr ₂ O ₃ layer 86C Cr ₂ O ₃ layer 86D MnCo ₂ O ₄ layer 86E Current collecting film 88 Fuel gas flow path 89 Insulating support 90 Inner electrode layer 90a Upper part 90b Outer peripheral face 90c Upper end face 91 Silver foil 91A Ring part 91B Strip part 91C Bending part 91D Cut 92 Outer electrode layer 93A First silver paste 93B First No. 2 silver paste 93C Third silver paste 94 Electrolyte layer 96 Glass seal 98 Fuel gas flow path 100 Upper support plate 102 Current collector 102a Fuel electrode connection portion 102b Air electrode connection portion 104 External terminal 111 Exhaust port 112 Mixed gas Supply pipe 120 Reformer 120A Mixed gas receiving unit 120B Reforming unit 12 C Gas exhaust part 120a Mixed gas supply port 120b Through hole 120c Reforming part 121 Upper case 122 Lower case 123a Partition plate 123b Partition plate 130 Exhaust gas guide member 131 Lower guide plate 131a Stepped part 132 Upper guide plate 132a Concave 133 Connecting plate 134 Connecting plate 135 Gas reservoir 140 Evaporator 140A Exhaust passage section 140B Evaporating section 140C Mixing section 141 Evaporator case 142 Upper case 142a Upper case inner wall 142b Upper case inner wall 142c Hump 143 Lower case 143a In lower case Bottom surface 143b collar 143c outer bottom surface of lower case (outer bottom surface of exhaust passage chamber)
143d Side wall surface of lower case 144 Intermediate plate 144a Opening 144b Lower side surface of intermediate plate 144c Upper side surface of intermediate plate 145 Partition plate (second heat transfer plate)
145a Communication hole (slit)
146 Partition plate (first heat transfer plate)
146a Communication hole (slit) (exhaust vent)
147 Partition plate (first heat transfer plate)
147a Communication hole (slit) (exhaust vent)
148 Partition plate 148a Communication hole (slit)
160 Power supply air supply case 160a Top plate 160b Side plate 161 Power generation air supply passage 161a Air passage 161b Air passage 162 Plate fin 163 Plate fin 171 Exhaust pipe 171a Exhaust pipe outlet 172 Exhaust passage 172a Exhaust gas inlet 173 Exhaust passage 174 Exhaust Passage 175 Plate fin 189 Conductive support 191 Silver foil 191C Bending part 193A First silver paste

Claims (7)

A fuel cell stack that generates power using fuel gas and oxidant gas,
A cylinder having a fuel electrode layer having a fuel passage to which the fuel gas is supplied, an air electrode layer to which the oxidant gas is supplied, and a solid electrolyte layer provided between the fuel electrode layer and the air electrode layer A fuel cell, and
A current collecting member provided so as to surround at least one end of the fuel battery cell, and taking out the electric power generated by the fuel battery cell from the fuel battery cell;
The fuel cell is electrically connected to the current collecting member via a flexible foil-like metal member,
The foil-shaped metal member is connected to the fuel cell and the current collecting member by a conductive paste,
The foil-like metal member is deformed to connect between the fuel cell and the current collecting member in a bent state, thereby following the stress applied to the fuel cell,
The foil-shaped metal member allows the current collection of the fuel cell so that the upper surface or the lower surface of the fuel cell can be displaced with respect to the top surface or the bottom surface of the current collection member facing the upper surface or the lower surface. A fuel cell stack characterized by being connected to a member. The foil-shaped metal member is connected in surface contact with the upper surface or the lower surface of the fuel cell,
The foil-shaped metal member is connected in a state of surface contact with the inner wall side surface of the current collecting member,
The fuel cell stack according to claim 1, wherein an upper surface or a lower surface of the fuel cell is not fixedly connected to a top surface or a bottom surface of the current collecting member facing the upper surface or the lower surface. One surface of the foil-shaped metal member is connected to the upper surface or the lower surface of the fuel cell,
The foil-shaped metal and the top or bottom surface of the current collecting member are temporarily fixed to the other surface portion of the foil-shaped metal member corresponding to the portion where the fuel cells are connected before firing. The fuel cell stack according to claim 2, wherein a temporary fixing member for releasing the temporary fixing after firing is provided.   4. The fuel cell stack according to claim 3, wherein one surface of the foil-shaped metal member is connected to an upper surface or a lower surface of the fuel cell by a conductive paste. The temporary fixing member is made of the same material as the conductive paste that connects the foil-shaped metal member to the fuel cell,
The fuel cell stack according to claim 4, wherein the conductive paste has higher adhesion to the fuel cell than the current collecting member.   The fuel cell stack according to claim 5, wherein the current collecting member has a chromium oxide layer on an inner wall surface. The fuel cell stack according to any one of claims 1 to 6,
A module case for housing the fuel cell stack;
A solid oxide fuel cell, comprising: a reformer disposed in the module case and reforming a raw fuel gas with water vapor to generate a fuel gas and supplying the fuel gas to the fuel cell stack apparatus.

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