JP2018045935A - Fuel battery cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery cell stack in which good connecting state between fuel battery cells and corresponding current collecting members can be maintained over a long period of time.SOLUTION: A fuel battery cell stack (14) according to the present invention comprises fuel battery cells (16) electrically connected by current collecting members (102). The fuel battery cells each include: an inner electrode layer (90); a solid electrolyte layer (94); and an outer electrode layer (92). Each current collecting member has: a connection electrode part (86) put in electrical conduction with the inner electrode layer; a first grasping part (104) connected thereto; a second grasping part (106) grasping the outer electrode layer of the adjacent fuel battery cell and connected thereto; and a joint (108) connecting between the first and second grasping parts, and putting them in mutual electrical conduction. The first grasping part grasping the connection electrode part, and the second grasping part grasping the outer electrode layer are arranged so that a grasping force for grasping one of the connection electrode part and outer electrode layer grasped by them, which is higher in surface strength becomes larger.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a fuel cell stack, and in particular, a fuel cell in which a plurality of solid oxide fuel cells that generate power by reacting a fuel gas and an oxidant gas are electrically connected by a current collecting member. Regarding the 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.

  A solid oxide fuel cell that generates a power generation reaction between a fuel gas and an oxidant gas has a very small electromotive force for each cell. Are connected in series to form a fuel cell stack, and electric power is taken out from the fuel cell stack.

  Japanese Patent No. 5578332 (Patent Document 1) describes a fuel cell assembly and a fuel cell. The fuel cell assembly (fuel cell stack) described here has sixteen fuel cells arranged in two rows of eight, and each adjacent fuel cell is for current collection. It is comprised by electrically connecting with the current collection member which is metal fittings. Each fuel cell is a cylindrical cell having a fuel electrode layer, a solid electrolyte layer, and an air electrode layer (oxidant gas electrode layer) in order from the inside, and a gas flow for flowing a fuel gas therein. There is a road. The fuel electrode layer formed inside the fuel cell is connected to metal caps attached to both ends of the fuel cell, and the outer air electrode layer is connected to the outside between the metal caps at both ends. Exposed.

  In addition, the current collecting member for connecting the fuel cells is configured to electrically connect the fuel cells by holding the metal cap of the fuel cells at one end and the air electrode layer of the adjacent fuel cells at the other end. Are connected in series. That is, the fuel cell is fitted into the end of the current collecting member by elastically deforming the end of the current collecting member, and both ends of the current collecting member are connected to the metal cap of the fuel cell and the air electrode layer. Holding each one. Moreover, the intermediate part of each current collection member is comprised from the metal thin plate orient | assigned so that it might extend in the common tangent plane of the two cylindrical fuel cells connected.

Japanese Patent No. 5578332

  Here, the fuel cells constituting the fuel cell stack and the current collecting member both undergo thermal expansion during the power generation operation exposed to high temperatures. Here, since the thermal expansion coefficient of the fuel battery cell and the current collecting member are different, when thermal expansion occurs, the thermal stress between the fuel battery cell and the current collecting member is based on the difference in the amount of deformation. Occurs. Due to this thermal stress, the current collecting member may be peeled off from the fuel cell and fall off. In order to prevent the current collecting member from peeling and dropping due to the thermal stress, in the fuel cell described in Patent Document 1, the end portion of the fuel cell is elastically held by the current collecting member. However, in the fuel cell described in Patent Document 1, the current collecting member can be prevented from falling off from the fuel cell, but the connection state between the fuel cell and the current collecting member is deteriorated due to a temperature rise or secular change. There is a problem that the general connection resistance increases.

  Accordingly, an object of the present invention is to provide a fuel cell stack that can maintain a good connection state between a fuel cell and a current collecting member for a long period of time.

  In order to solve the above-described problems, the present invention provides a fuel cell in which a plurality of solid oxide fuel cells that generate power by reacting a fuel gas and an oxidant gas are electrically connected by a current collecting member. Each of the fuel cell units includes an inner electrode layer, a solid electrolyte layer provided outside the inner electrode layer, and an outer electrode layer provided outside the solid electrolyte layer. In addition, the gas passage for flowing the fuel gas or oxidant gas is formed inside so that the fuel gas or oxidant gas is supplied to the inner electrode layer. A first electrode that is connected to the first electrode, and a second electrode that is connected to the outer electrode layer of the adjacent fuel cell, and a first electrode that is connected to the first electrode. Connect the gripping part and the second gripping part and connect them A first gripping portion that grips the connection electrode portion and a second gripping portion that grips the outer electrode layer are the surface of the gripping connection electrode portion or outer electrode layer. It is characterized by a strong gripping force for gripping the higher strength.

  In the present invention configured as described above, a plurality of solid oxide fuel cells are electrically connected by a current collecting member to form a fuel cell stack. Each fuel cell includes an inner electrode layer, an outer solid electrolyte layer, and an outer electrode layer on the outer side, and a gas passage is formed inside. The current collecting member grips the connection electrode portion that is electrically connected to the inner electrode layer, holds the first grip portion connected thereto, and the outer electrode layer of the adjacent fuel cell, and connects the first electrode portion connected thereto. 2 gripping portions, and a connecting portion that connects the first gripping portion and the second gripping portion. The first gripping part for gripping the connection electrode part and the second gripping part for gripping the outer electrode layer have a gripping force for gripping the higher surface strength of the connection electrode part or the outer electrode layer being gripped. ing.

  In general, in a fuel cell device, a large number of fuel cells are electrically connected in series by current collecting members to obtain a desired output voltage. The current collecting member for connecting the fuel cells is configured to electrically connect the fuel electrode of one fuel cell and the oxidant gas electrode of another fuel cell, and the fuel electrode and the oxidant gas. A current collecting member is generally attached directly to the outer electrode layer that is exposed to the outside of the poles. Here, in order to maintain a good connection state between the fuel battery cell and the current collecting member for a long period of time, it is desirable to set the gripping force with which the current collecting member grips the fuel battery cell strongly. That is, by holding the fuel cell with the current collecting member with a strong gripping force, even when a thermal stress acts between the fuel cell and the current collecting member, the current collecting member is prevented from peeling off or falling off. In addition, since a strong contact force acts between the current collecting member and the fuel cell, the electrical contact resistance between them can be kept low.

  However, if the gripping force of the current collecting member that grips the fuel cell is too strong, when the current collecting member grips the fuel cell, the surface of the fuel cell is scratched and the cell is damaged. There's a problem. According to the present invention configured as described above, the first gripping part that grips the connection electrode part and the second gripping part that grips the outer electrode layer are the connection electrode part or the outer electrode layer that is gripped, The gripping force for gripping the surface having a higher surface strength is strong. As a result, the gripping force can be appropriately set according to the surface strength of the portion gripped by the current collecting member, and a strong contact force can be obtained while preventing damage to the fuel battery cell. The electrical contact resistance between the member and the fuel cell can be kept low.

  In the present invention, preferably, the first gripping part grips the connection electrode part by extending along the periphery of the connection electrode part, and the second gripping part extends the outer electrode layer by extending along the periphery of the outer electrode layer. The first gripping portion and the second gripping portion that are gripped are configured to have long lengths that extend to the periphery when the gripping force is strong.

  According to the present invention configured as described above, since the first gripping portion and the second gripping portion are configured to have a longer length extending around the strong gripping force, the first gripping portion and the first gripping portion have a simple structure. The gripping force by the part and the second gripping part can be set appropriately.

  In the present invention, preferably, the first gripping part grips the connection electrode part by extending along the periphery of the connection electrode part, and the second gripping part extends the outer electrode layer by extending along the periphery of the outer electrode layer. The first grip portion and the second grip portion have different widths so as to obtain a predetermined grip force.

  According to the present invention configured as described above, the first gripping portion and the second gripping portion have different widths so as to obtain a predetermined gripping force. The gripping force by the second gripping part can be set appropriately.

  In the present invention, preferably, the first grip portion and the second grip portion extend longer than a half circumference around the connection electrode portion and the outer electrode layer, respectively.

  According to the present invention configured as described above, the first gripping portion and the second gripping portion extend longer than a half circumference around the connection electrode portion and the outer electrode layer, respectively. The battery cell can be securely gripped.

  In the present invention, preferably, a conductive bonding agent is disposed between the first gripping portion and the connection electrode portion and / or between the second gripping portion and the outer electrode layer, and the first is formed by the conductive bonding agent. The grip part and / or the second grip part and the fuel cell are joined.

  According to the present invention configured as described above, the conductive bonding agent is disposed between the first grip portion and the connection electrode portion and / or between the second grip portion and the outer electrode layer. Since the gripping part and / or the second gripping part and the fuel battery cell are connected not only by the gripping force by the gripping part but also by the joining force by the conductive bonding agent, the gripping force by the gripping part is caused by secular change or the like. Even when it drops, a good connection state can be maintained.

  In the present invention, preferably, the connection electrode part connected to the first grip part is composed of a metal cap that is attached to the end part of the fuel cell and is electrically connected to the inner electrode layer, and the first grip part is The gripping force is configured to be stronger than the second gripping part.

  According to the present invention configured as described above, the connection electrode portion is composed of a metal cap that is electrically connected to the inner electrode layer, and the first gripping portion that grips the cap has a gripping force stronger than the second gripping portion. Since it is configured, it becomes possible to set the gripping force by the first gripping part sufficiently strong so that even if it is gripped with a strong gripping force, it is possible to set a sufficiently strong gripping state over a long period of time. Can be maintained.

  According to the fuel cell stack of the present invention, a good connection state between the fuel cell and the current collecting member can be maintained for a long time.

1 is an overall configuration diagram showing a solid oxide fuel cell device (SOFC) incorporating a fuel cell stack according to an embodiment of the present invention. It is side surface sectional drawing which shows the fuel cell module provided with the fuel cell stack by embodiment of this invention. FIG. 3 is a cross-sectional view of the fuel cell module taken along line III-III in FIG. 2. 1 is an exploded perspective view of a module case and an air passage cover that accommodate a fuel cell stack according to an embodiment of the present invention. It is a figure which shows the fuel cell which comprises the fuel cell stack by embodiment of this invention. It is an expanded sectional view of the fuel cell end part which constitutes the fuel cell stack according to the embodiment of the present invention. 1 is a perspective view showing a fuel cell stack according to an embodiment of the present invention. It is a side view which shows a part of fuel cell stack by embodiment of this invention. It is side surface sectional drawing which shows a part of fuel cell stack by embodiment of this invention. It is a perspective view of a current collection member which constitutes a fuel cell stack according to an embodiment of the present invention. It is the top view which looked at the two fuel battery cells connected by the current collection member which comprises the fuel battery cell stack by embodiment of this invention from upper direction.

Next, a solid oxide fuel cell device including a fuel cell stack according to an 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 device (SOFC) incorporating a fuel cell stack according to an embodiment of the present invention.
As shown in FIG. 1, a solid oxide fuel cell apparatus (SOFC) 1 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 stack 14 is arranged. In the present embodiment, the fuel cell stack 14 has all of the plurality of fuel cells 16 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 incorporating the fuel cell stack according to the present embodiment will be described with reference to FIGS.
2 is a side sectional view showing a fuel cell module of the solid oxide fuel cell device, FIG. 3 is a sectional view taken along line III-III in FIG. 2, and FIG. 4 is a module case and air. It is a disassembled perspective view of a channel | path cover.

  As shown in FIGS. 2 and 3, the fuel cell module 2 includes a fuel cell stack 14 and a reformer 120 provided inside a module case 8 covered with a heat insulating material 7. The evaporator 140 is provided outside and 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 stack 14 (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 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, in this embodiment, the evaporator 140 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 in the horizontal direction along the longitudinal direction of the module case 8, and is fixed to the top plate 8a. 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 enters the manifold 66 formed below, and further extends in the horizontal direction to the vicinity of the closed side plate 8e on the opposite side in the manifold 66. 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 16. . An ignition device 83 for starting combustion of fuel gas and air is provided in the combustion chamber 18.
Further, the reformer 120 is disposed at a predetermined horizontal distance from the side plate 8b of the module case 8.

Next, the fuel cell 16 will be described with reference to FIGS. 5 and 6.
FIG. 5 is a view showing the fuel cells constituting the fuel cell stack according to the embodiment of the present invention. FIG. 6 is an enlarged cross-sectional view of the end portion of the fuel battery cell.
As shown in FIG. 5, the fuel battery cell 16 includes a fuel battery cell main body 84 and caps 86 that are connection electrode portions respectively connected to both ends of the fuel battery cell main body 84.

  As shown in FIG. 6, the fuel cell body 84 in the case of having a conductive support as a support is a tubular structure that extends in the vertical direction, and has a cylindrical shape that forms a fuel gas flow path 88 that is a gas passage therein. An inner electrode layer 90 as a fuel electrode layer, an electrolyte layer 94 as a cylindrical solid electrolyte layer provided on the outer periphery of the inner electrode layer 90, and a cylindrical air electrode provided on the outer periphery of the electrolyte layer 94 ( And an outer electrode layer 92 that is an oxidant gas electrode layer. The inner electrode layer 90 is a porous body that functions as a support that constitutes the fuel cell main body 84 and that constitutes a gas passage through which fuel gas flows. The inner electrode layer 90 is a fuel electrode, which is a (−) electrode, while the outer electrode layer 92 is an air electrode in contact with air, which is a (+) electrode.

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.
A porous insulating support can also be used as the support. In this case, a fuel electrode layer is formed as an inner electrode layer outside the insulating support.

  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 cap 86 will be described. Since the caps 86 attached to the upper end side and the lower end side of the fuel cell body 84 have the same structure, the cap 86 is attached to the lower end side of the fuel cell body 84 here. The cap 86 will be specifically described.

  The cap 86 is provided so as to surround the upper and lower ends of the fuel cell main body 84, and is electrically connected to the inner electrode layer 90 of the fuel cell main body 84, and serves as a connection electrode that pulls the inner electrode layer 90 to the outside. Function. As shown in FIG. 6, the cap 86 provided at the lower end of the fuel cell main body 84 has a cylindrical first cylindrical portion 86a and an annular shape extending outward from the upper end of the first cylindrical portion 86a. It has an annular part 86b and a second cylindrical part 86c extending upward from the outer periphery of the annular part 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 cap 86. The fuel gas flow path 98 is an elongated pipe line provided so as to extend in the axial direction of the fuel cell main body 84 from the center of the cap 86.

In the cap 86, chromium oxide (Cr ₂ O _{3 in} this embodiment) is coated on the inner peripheral surface and outer peripheral surface of a main body made of ferritic stainless steel or austenitic stainless steel, and the outer peripheral surface is coated with MnCo ₂ O. ₄ is coated. In addition, an Ag current collecting film is provided on the outer peripheral surface of the coated MnCo ₂ O ₄ layer. In this embodiment, the Ag current collector film is provided over the entire outer peripheral surface of the cap 86, but may be provided only in part.

  A silver paste 95 is disposed in the space between the inside of the second cylindrical portion 86 c of the cap 86 and the outer peripheral surface of the end portion of the inner electrode layer 90 of the fuel cell body 84. By firing after assembling the fuel cell 16, the silver paste 95 is sintered, and the inner electrode layer 90 and the cap 86 are electrically and mechanically coupled. A glass seal 96 made of a glass material is provided between the inner peripheral surface of the second cylindrical portion 86 c of the cap 86 and the outer peripheral surface of the lower end portion of the electrolyte layer 94. The glass seal 96 hermetically seals the space between the cap 86 and the inner electrode layer 90 with respect to the space outside the fuel cell 16.

Next, the fuel cell stack 14 according to the embodiment of the present invention will be described with reference to FIGS. 7 to 11.
FIG. 7 is a perspective view showing the fuel cell stack according to the present embodiment. FIG. 8 is a side view showing a part of the fuel cell stack according to the present embodiment, and FIG. 9 is a side sectional view showing a part of the fuel cell stack.

As shown in FIG. 7, the fuel cell stack 14 includes 128 fuel cells 16 arranged in a lattice pattern, and these fuel cells 16 are arranged in 16 rows of 16 each.
As shown in FIGS. 8 and 9, each fuel cell 16 is supported at its lower end side by a rectangular lower support plate 68 made of metal. The lower support plate 68 constitutes a ceiling surface of the manifold 66, and a through hole for allowing the fuel gas to flow into the fuel gas flow path 88 of each fuel cell 16 is formed. In addition, a substantially cylindrical ceramic spacer 100 is disposed between the cap 86 on the lower end side of each fuel cell 16 and the lower support plate 68, and the cap 86 and the lower support plate 68 are separated from each other. This ensures insulation.

  Furthermore, a current collecting member 102 that electrically connects one fuel cell 16 to the adjacent fuel cell 16 is attached to each fuel cell 16. The current collecting member 102 connects the cap 86 electrically connected to the inner electrode layer 90 that is the fuel electrode and the outer peripheral surface of the outer electrode layer 92 that is the air electrode of the adjacent fuel cell 16. Placed in. Further, since each current collecting member 102 is attached to the upper end portion and the lower end portion of each fuel battery cell 16, the fuel battery cells 16 adjacent to one fuel battery cell 16 are electrically connected by the two current collector members 102. (The two current collecting members 102 are in parallel). As described above, all the fuel cells 16 constituting the fuel cell stack 14 are electrically connected in series by the respective current collecting members 102. A silver thin film is formed on the entire outer surface of the outer electrode layer 92 (air electrode) of each fuel cell 16 as an electrode on the air electrode side. When the current collecting member 102 contacts the surface of the thin film, the current collecting member 102 is electrically connected to the entire air electrode.

Next, a connection structure using the current collecting member 102 will be described with reference to FIGS. FIG. 10 is a perspective view of the current collecting member. FIG. 11 is a plan view of the two fuel cells connected by the current collecting member as seen from above.
As shown in FIG. 10, the current collecting member 102 includes a first grip 104 configured to grip the cap 86, a second grip 106 configured to grip the outer electrode layer 92, 1. It is comprised from the connection part 108 which connects the 2nd holding | grip part and electrically conducts these. The current collecting member 102 is a metal fitting in which the first and second gripping portions and the connecting portion are integrally formed by bending a ferritic stainless steel thin plate. Further, the surface of the current collecting member 102 is silver-plated to improve its electrical conductivity. That is, the current collecting member 102 is configured by coating a ferritic stainless steel base material with a silver metal layer having a lower electrical resistivity than the base material.

  The first grip 104 is an elongated rectangular thin plate curved in an arc shape, and the cap 86 is gripped by the first grip 104 by fitting the cap 86 inside the arc. That is, in the non-assembled state, the radius of the arc-shaped first gripping portion 104 is slightly smaller than the radius of the cap 86, and the first gripping portion 104 is elastically deformed at the time of assembly while being inward of the first gripping portion 104. The cap 86 is gripped by fitting. Further, the tip portions 104a on both sides of the first grip portion 104 are curved outward from the center of the fuel cell 16 (cap 86), and the corners of the tip portion 104a are rounded. . Accordingly, when the cap 86 is fitted into the first grip portion 104, the front end portion 104a of the first grip portion 104 is prevented from being damaged on the surface of the cap 86.

  When the cap 86 is gripped, the first grip 104 extends along a predetermined range around the cap 86, and the inner surface of the first grip 104 and the outer peripheral surface of the second cylindrical portion 86c of the cap 86 are Contact. When assembled, the first grip 104 extends longer than the half circumference of the second cylindrical portion 86 c of the cap 86. That is, the first grip 104 is configured to be longer than half of the circumference around the cap 86. Further, at the time of assembly, a silver paste that is a conductive bonding agent is applied between the inner peripheral surface of the first grip portion 104 and the outer peripheral surface of the second cylindrical portion 86c. After the assembly of the fuel cell stack 14 is completed, the applied silver paste is sintered, so that the first grip 104 and the cap 86 are fixed.

  The second grip 106 is an elongated rectangular thin plate curved in an arc shape, and the fuel cell main body 84 is fitted into the second grip by inserting the fuel cell main body 84 of the fuel cell 16 inside the arc. 106. The second grip 106 grips a portion of the outer electrode layer 92 (air electrode) of the fuel cell main body 84. Further, in the non-assembled state, the radius of the arc-shaped second gripping portion 106 is slightly smaller than the radius of the outer electrode layer 92, and the second gripping portion 106 is elastically deformed during assembly while the second gripping portion 106 is elastically deformed. By fitting inside, the part of the outer electrode layer 92 is gripped. The tip portions 106a on both sides of the second gripping portion 106 are curved outward from the center of the fuel cell 16 (outer electrode layer 92), and the corners of the tip portion 106a are rounded. ing. Thereby, when the fuel cell main body 84 is fitted into the second grip portion 106, the front electrode 106 a of the second grip portion 106 is prevented from being damaged on the surface of the outer electrode layer 92.

  Further, in a state where the fuel cell body 84 is gripped, the second gripping portion 106 extends along a predetermined range around the outer electrode layer 92, and the outer electrode contact surface 106 b and the outer electrode layer inside the second gripping portion 106. The outer peripheral surface of 92 contacts. When assembled, the second grip 106 extends longer than a half circumference of the outer electrode layer 92, but the second grip 106 is shorter than the first grip 104 and is shorter than the first grip 104. It extends over a small area. In other words, the second grip 106 is configured to be longer than half the circumference of the circumference of the outer electrode layer 92, but is configured to be shorter than the first grip 104. On the other hand, the second grip 106 is formed wider than the first grip 104 and the grip force is adjusted.

  That is, since the second grip 106 is formed shorter than the first grip 104, the amount of elastic deformation when the fuel cell 16 is fitted is smaller than that of the first grip 104. For this reason, the force required to fit the outer electrode layer 92 into the second gripping portion 106 is weaker than the force required to fit the cap 86 into the first gripping portion 104, and the gripping force is greater than that of the first gripping portion 104. However, the outer electrode layer 92 can be easily fitted into the second grip 106. This prevents the surface of the outer electrode layer 92 from being damaged when the fuel battery cell 16 is fitted into the second grip 106.

  On the other hand, since the cap 86 fitted into the first grip 104 has a surface strength higher than that of the outer electrode layer 92 and is not easily damaged, the surface is damaged even if the force required for fitting is set large. Less is. By setting a large amount of elastic deformation of the first gripping portion 104 during assembly, the first gripping portion 104 can grip the cap 86 with a strong gripping force, and the current collecting member 102 is firmly attached to the cap 86. Can be attached. Thus, in the fuel cell stack 14 of the present embodiment, the surface strength is high so that the gripping force by the first and second gripping portions is appropriately set according to the surface strength of the portion where the first and second gripping portions are assembled. Since the gripping force for gripping one side is strengthened, a strong gripping force can be obtained while preventing the assembled surface from being damaged.

  Further, at the time of assembly, a silver paste that is a conductive bonding agent is disposed between the inner peripheral surface of the second grip portion 106 and the outer peripheral surface of the outer electrode layer 92. That is, the portion of the outer electrode layer 92 of the fuel cell 16 is fitted into the second grip 106 with the silver paste applied to the inner peripheral surface of the second grip 106. After the assembly of the fuel cell stack 14 is completed, the applied silver paste is sintered, so that the second grip 106 and the outer electrode layer 92 are fixed. Thereby, the 2nd holding part 106 and the outer side electrode layer 92 contact via the bonding agent layer formed with the sintered silver paste. Note that the silver paste may be applied to only one of the first grip portion 104 and the second grip portion 106.

  Further, the second grip 106 is provided with gas supply openings 106c and 106d, which are gas supply units. The gas supply opening 106 d is a circular opening provided at the center of the second grip 106. Further, the gas supply opening 106c is an elongated slit-like opening formed to extend on both sides of the gas supply opening 106d along the longitudinal direction of the second grip 106, and the second grip 106 is When attached to the fuel cell 16, the gas supply opening 106 d extends in the circumferential direction of the fuel cell 16. Here, when the current collecting member 102 is assembled to the fuel cell 16, the outer electrode contact surface 106 b of the second grip portion 106 comes into contact with the outer electrode layer 92. As a result, a part of the outer electrode layer 92 is covered, and the supply of the oxidant gas (air) is hindered in the covered part. However, by providing the gas supply openings 106c and 106d, An oxidant gas is supplied to the outer electrode layer 92 through the opening.

  Here, the area covered by the second grip 106 has an effect on the power generation reaction in the portion where the supply of the oxidant gas is hindered, and the power generation efficiency of the fuel cell 16 is reduced, so the area covered is small. Is desirable. However, in order to join the second gripping portion 106 to the outer electrode layer 92 with a sufficient strength using silver paste, the contact area between the second gripping portion 106 and the outer electrode layer 92 (outer electrode contact surface 106b) Must be secured to some extent.

  In the fuel cell stack 14 of the present embodiment, since the gas supply openings 106c and 106d are provided in the second grip 106, the oxidant gas flows around these openings to some extent. For this reason, by providing the gas supply openings 106c and 106d and subdividing the outer electrode contact surface 106b, the adverse effect of covering the outer electrode layer 92 with the second grip portion 106 can be alleviated. Further, by providing the gas supply openings 106c and 106d in the second grip 106, the outer electrode contact surface 106b that covers the outer electrode layer 92 is subdivided, so that the power generation reaction of the outer electrode layer 92 is reduced. The portion to be suppressed (outer electrode contact surface 106b) is dispersed, and unevenness in the power generation reaction can be suppressed. As described above, a silver paste is applied between the second gripping portion 106 and the outer electrode layer 92, but the bonding agent layer formed by sintering the silver paste has a gas supply opening 106c. , 106d is formed to a thickness that does not exceed the thickness of the bonding agent layer in the outer electrode contact surface 106b. Therefore, sufficient oxidant gas is supplied to the outer electrode layer 92 through the gas supply opening.

  Next, the connecting part 108 is a plate-like part that connects the first gripping part 104 and the second gripping part 106, and the first gripping part 104 and the second gripping part connected to both ends of the connecting part 108. The portions 106 are curved in directions opposite to each other. The connecting portion 108 includes a first trapezoidal portion 108a connected to the first gripping portion 104, a second trapezoidal portion 108b connected to the second gripping portion 106, a first trapezoidal portion 108a, and a second trapezoidal portion. And a widened portion 108c extending between the portions 108b.

  The first trapezoidal part 108a is an isosceles trapezoidal thin plate, and the shorter parallel opposite side is connected to the central part of the first gripping part 104, and the longer opposite side is connected to the widened part 108c. Here, the shorter opposite side of the first trapezoidal portion 108a is connected to the first gripping portion 104 along a connecting curve 108d. That is, since the first grip 104 is curved along the outer peripheral curved surface of the fuel cell 16 (cap 86) to be gripped, the connecting curve 108d (first trapezoid) connecting the first trapezoid 108a. The shorter side of 108a is also a curve. On the other hand, the widened portion 108c is a plane, and the longer opposite side of the first trapezoidal portion 108a connected to the widened portion 108c is a straight line.

  Similarly, the second trapezoidal part 108b is an isosceles trapezoidal thin plate, and the shorter parallel opposite side is connected to the central part of the second gripping part 106, and the longer opposite side is connected to the widened part 108c. Yes. Further, the shorter opposite side of the second trapezoidal part 108b is connected to the second gripping part 106 along a connection curve 108e. That is, the second grip 106 is curved along the curved surface of the outer periphery of the fuel cell 16 to be gripped (the outer electrode layer 92 thereof), and therefore the connection curve 108e (second curve) that connects the second grip 106 and the second trapezoid 108b. The shorter side of the trapezoidal portion 108b) is also a curve. On the other hand, the longer opposite side of the second trapezoidal part 108b connected to the widened part 108c which is a plane is a straight line.

  Next, the widened portion 108c is a substantially rectangular flat plate that connects between the first trapezoidal portion 108a and the second trapezoidal portion 108b, and has substantially the same width as the longer opposite side of the first and second trapezoidal portions. Is formed. Here, since the current collecting member 102 is a member that electrically connects the adjacent fuel cells 16, the connecting portion 108 that connects the first grip portion 104 and the second grip portion 106 has a conductor cross-sectional area. It is desirable to increase the electrical resistance to reduce the electrical resistance. However, since the connecting curves 108d and 108e connecting the first and second gripping portions and the connecting portion 108 are curved in opposite directions, if these connecting curves become too long, the metal thin plate is bent. Thus, it is difficult to form the current collecting member 102 that connects the connecting curves on both sides.

  Therefore, in the present embodiment, the first trapezoidal portion 108a and the second trapezoidal portion 108b are provided at both ends of the connecting portion 108, respectively, so that the connecting portion 108 and the first and second gripping portions are connected to each other ( The length of the connecting curves 108d and 108e) is kept short. At the same time, by increasing the width of the widened portion 108c connecting the first and second trapezoidal portions, the conductor cross-sectional area of this portion is increased, and the electrical resistance of the current collecting member 102 as a whole is reduced. Accordingly, the widened portion 108c provided in the intermediate portion of the connecting portion 108 is formed wider than the connecting curves 108d and 108e, and functions as an electric resistance reducing means.

Next, with reference to FIG.8 and FIG.11, the connection state of each fuel cell by a current collection member is demonstrated.
As shown in FIGS. 8 and 11, the first grip 104 of the current collecting member 102 grips the cap 86 of the fuel cell 16, and the second grip 106 is the fuel cell body 84 of the adjacent fuel cell 16. (The outer electrode layer 92). In addition, each current collecting member 102 that connects adjacent fuel cells 16 is attached to be aligned in the horizontal direction at the upper end and the lower end of each fuel cell 16. As shown in FIG. 8, the connecting portion 108 that connects the first grip 104 and the second grip 106 extends obliquely from the first grip 104 to the second grip 106.

  Here, as shown in FIG. 8, the connecting portion 108 that connects the first grip portion 104 and the second grip portion 106 extends in a curved manner. As described above, when the connecting portion 108 is curved or bent, even if the distance between the two connected fuel cells 16 changes due to thermal expansion of each member, the change in the distance is detected. 108 can be easily absorbed by bending deformation. On the other hand, if the first grip 104 and the second grip 106 are linearly coupled, a change in distance between the connected fuel cells 16 cannot be absorbed by bending deformation. There is a risk that a large pulling force or compressive force acts on the connecting portion 108, whereby each gripping portion is peeled off from the fuel cell 16.

  Further, as shown in FIG. 11, since the plate surface of the generally flat connecting portion 108 is oriented in the vertical direction, the plate surface of the connecting portion 108 is the central axis of the connected fuel cells 16. It is orientated so as to be orthogonal to the plane P1 including. Further, since the connection lines (coupling curves 108d and 108e) between the first and second gripping portions and the connecting portion 108 are located on the plane P1, the connecting portion 108 connects the first gripping portion 104 and the second gripping portion 106. Connected in the shortest distance. That is, the current collecting member 102 connects the two fuel cells 16 to be connected to each other at the closest point (points A1 and A2 where the outer peripheral surface of the fuel cell 16 and the plane P1 intersect) in plan view. Therefore, the two fuel cells 16 can be connected at the shortest distance in plan view. In other words, the connecting portion 108 is a region inside the two common tangent planes P2 and P3 in contact with both of the two connected fuel cells 16 (the tangential plane P2 between the tangent planes P2 and P3, The connecting portion 108 can connect the first and second gripping portions at the shortest distance.

  On the other hand, as shown by imaginary lines in FIG. 8, a plurality of outlets 8 f which are oxidant gas supply holes for supplying oxidant gas to the oxidant gas electrode (outer electrode layer 92) of each fuel cell 16 are provided as modules. The case 8 is provided so as to face the side wall surfaces on both sides of the case 8 (FIG. 8). These air outlets 8 f inject a heated oxidant gas toward each fuel cell 16 from the lower side surface of each fuel cell 16 (fuel cell stack 14). Further, the respective outlets 8f are arranged in a straight line in the horizontal direction so as to inject the oxidant gas between the adjacent fuel cells 16.

  Here, since the plate surface of the connecting portion 108 is directed in the vertical direction, as shown in FIG. 8, the horizontal projected area from the side of the connecting portion 108 is equal to the plate thickness of the connecting portion 108. Only and is very narrow. For this reason, the flow resistance given to the flow of the oxidant gas between the respective fuel cells 16 in each of the current collecting members 102 (the connecting portion 108) becomes very small. In this way, by suppressing the flow resistance by each current collecting member 102, the oxidant gas injected from the side surface sufficiently reaches the fuel cell 16 located inside the fuel cell stack 14. For this reason, each fuel cell 16 is heated uniformly by the heated oxidant gas, and the temperature unevenness of the fuel cell 16 located in each part of the fuel cell stack 14 is reduced. Therefore, the connecting portion 108 of the current collecting member 102 functions as a flow resistance suppressing unit that suppresses the flow resistance of the oxidant gas injected between the fuel cells 16, thereby reducing temperature unevenness. The

  Further, as shown in FIG. 8, each current collecting member 102 that connects each fuel cell 16 belonging to one column and each current collecting member 102 that connects each fuel cell 16 belonging to an adjacent column, respectively. It is attached so as to extend in the opposite direction. That is, in FIG. 8, each current collecting member 102 that connects the upper ends of the fuel cells 16 in the front row is attached so as to incline upward from the second gripping portion 106 toward the first gripping portion 104. On the other hand, each current collecting member 102 connecting the upper end portions of the respective fuel cells 16 in the second row from the front is attached so as to incline to the left. Similarly, each current collecting member 102 that connects the lower end portions of the fuel cells 16 in the foremost row is attached so as to incline downward from the second gripping portion 106 toward the first gripping portion 104. On the other hand, each current collecting member 102 connecting the lower end portions of the respective fuel cells 16 in the second row from the front is attached so as to incline to the left.

  In this way, by attaching the current collecting members 102, as shown in FIG. 8, the current collecting members 102 are arranged so as to draw an "X" shape in a side view. As a result, the flow of the oxidant gas that has flowed in between the fuel battery cells 16 from the side surface of the fuel cell stack 14 is not directed in one direction by the current collecting members 102, and the oxidant gas is prevented from flowing into the fuel cell. It is possible to flow more evenly inside the cell stack 14 and suppress the temperature unevenness of each fuel cell 16.

Next, the operation of the fuel cell module including the fuel cell stack according to the embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 2, 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 and the exhaust pipe 171 in this order, the mixed gas in the mixed gas supply pipe 112 is further heated by the exhaust gas flowing through these passages.

  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 flowing 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 supplied from the manifold 66 into each fuel cell 16. Is done.

  Further, as shown in FIGS. 2 and 3, the power generation air is supplied from the power generation air introduction pipe 74 to the air passage 161a. When the air for power generation passes through the plate fins 162 and 163 in the air passages 161a and 161b, the air for generating electricity is separated from the exhaust gas passing through the exhaust passage formed in the module case 8 below the plate fins 162 and 163. Heat is efficiently exchanged between the two, and it is heated. Thereafter, power generation air is injected into the power generation chamber 10 from both sides toward the lower side surface of the fuel cell stack 14 from a plurality of outlets 8f provided at the lower portion of the side plate 8b of the module case 8. The lower part of each fuel cell 16 is heated by the heated air for power generation.

  In addition, the fuel gas that has not been used for power generation in the power generation chamber 10 flows out from the upper end of each fuel battery cell 16, is burned in the combustion chamber 18 to become exhaust gas (combustion gas), and rises in the module case 8. To go. Thereafter, the exhaust gas flows out from the exhaust port 111 formed at the center of the top plate 8 a of the module case 8.

  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.

  According to the fuel cell stack 14 of the embodiment of the present invention, the first grip portion 104 that grips the cap 86 that is the connection electrode portion and the second grip portion 106 that grips the outer electrode layer 92 are formed from the outer electrode layer 92. Also, the gripping force of the first gripping portion 104 that grips the cap 86 having a high surface strength is configured to be strong. Thus, the gripping force is appropriately set according to the surface strength of the portion gripped by the current collecting member 102, and a strong contact force can be obtained while preventing the fuel cell 16 from being damaged. As a result, the electrical contact resistance between the current collecting member 102 and the fuel battery cell 16 can be kept low.

  Further, according to the fuel cell stack 14 of the present embodiment, the first grip 104 and the second grip 106 are configured such that the length of the first grip 104 having a strong grip force extends to the periphery. (FIG. 10), the gripping force by the first gripping part 104 and the second gripping part 106 can be set appropriately with a simple structure.

  Furthermore, according to the fuel cell stack 14 of the present embodiment, the first grip 104 and the second grip 106 have different widths so as to obtain a predetermined grip force (FIG. 10). With a simple structure, the gripping force by the first gripper 104 and the second gripper 106 can be set appropriately.

  Further, according to the fuel cell stack 14 of the present embodiment, the first grip 104 and the second grip 106 are longer than a half circumference around the cap 86 and the outer electrode layer 92 that are connection electrode portions, respectively. Since it extends, the cylindrical fuel cell 16 can be reliably gripped.

  Furthermore, according to the fuel cell stack 14 of the present embodiment, the silver paste that is a conductive bonding agent is disposed between the first grip 104 and the cap 86 and between the second grip 106 and the outer electrode layer 92. Therefore, the first grip portion 104 and / or the second grip portion 106 and the fuel cell 16 are connected not only by the grip force by the grip portion but also by the joining force by the baked silver paste. Even when the gripping force by the gripping portion is reduced due to a change or the like, a good connection state can be maintained.

  Further, according to the fuel cell stack 14 of the present embodiment, the first grip portion 104 that grips the metal cap 86 that is electrically connected to the inner electrode layer 90 is configured to have a grip force stronger than that of the second grip portion 106. Therefore, it becomes possible to set the gripping force by the first gripping portion 104 that is not damaged even when gripping with a strong gripping force, and to set a good connection state over a long period of time. Can be maintained.

  As mentioned above, although preferable embodiment of this invention was described, a various change can be added to embodiment mentioned above. In particular, in the above-described embodiment, the fuel electrode is provided as the inner electrode layer of the fuel cell, and the oxidant gas (air) electrode is provided as the outer electrode layer. The present invention can also be applied to a stack of arbitrary cylindrical fuel cells provided with a fuel electrode on the outside. In the above-described embodiment, one gas passage is provided in one fuel cell, but a plurality of fuel or oxidant gas passages are provided in one fuel cell. The present invention can also be applied to a stack of cylindrical fuel cells.

  Further, in the above-described embodiment, the inner electrode layer that is the fuel electrode is connected to the cap that is the connection electrode portion, and this cap is connected to the adjacent outer electrode layer by the current collecting member. However, the connection electrode part is not limited to the cap, and the connection electrode part can be constituted by an arbitrary conductor connected to the inner electrode layer, and the connection electrode part can be integrally formed with the inner electrode layer.

1 Solid oxide fuel cell system (SOFC)
DESCRIPTION OF SYMBOLS 2 Fuel cell module 4 Auxiliary machine unit 6 Housing 7 Heat insulating material 8 Module case 8a Top plate 8b Side plate 8c Bottom plate 8d, 8e Closed side plate 8f Outlet 10 Power generation chamber 14 Fuel cell stack 16 Fuel cell 18 combustion chamber (combustion part)
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 44 Reforming air flow rate adjustment unit 45 Power generation air flow rate adjustment unit 46 First heater 48 Second heater DESCRIPTION OF SYMBOLS 50 Hot water manufacturing apparatus 52 Control box 54 Inverter 63 Fuel supply piping 64 Fuel gas supply pipe 64a Horizontal part 64b Fuel supply hole 65 Hydrogen extraction pipe for hydrodesulfurization 66 Manifold 68 Lower support plate 82 Exhaust gas discharge pipe 83 Ignition device 84 Fuel cell Cell body 86 Cap (connection electrode part)
86a 1st cylindrical part 86b Annular part 86c 2nd cylindrical part 88 Fuel gas flow path 90 Inner electrode layer 92 Outer electrode layer 94 Electrolyte layer (solid electrolyte layer)
95 Silver paste 96 Glass seal 98 Fuel gas flow path 100 Spacer 102 Current collecting member 104 First grip portion 104a Tip portion 106 Second grip portion 106a Tip portion 106b Outer electrode contact surface 106c, 106d Gas supply opening portion 108a Connection portion 108a First 1 trapezoidal part 108b 2nd trapezoidal part 108c widening part 108d connection curve 108e connection curve 111 exhaust port 112 mixed gas supply pipe 120 reformer 121 upper case 122 lower case 123a, 123b partition plate 140 evaporator 141 evaporator case 142 upper side Case 143 Lower case 144 Intermediate plate 146, 147 Partition plate 160 Air passage covers 161a, 161b Air passages 162, 163 Plate fin 167 Opening 171 Exhaust pipe

Claims (6)

A fuel cell stack in which a plurality of solid oxide fuel cells that generate power by reacting a fuel gas and an oxidant gas are electrically connected by a current collecting member,
Each of the fuel cells includes an inner electrode layer, a solid electrolyte layer provided outside the inner electrode layer, and an outer electrode layer provided outside the solid electrolyte layer, and the fuel gas. Alternatively, the gas passage for flowing the fuel gas or the oxidant gas is formed in a cylindrical shape so that the oxidant gas is supplied to the inner electrode layer,
The current collecting member grips the connection electrode portion that is electrically connected to the inner electrode layer, grips the first grip portion connected thereto, and the outer electrode layer of the adjacent fuel cell, A second gripping part to be connected; and a coupling part for coupling the first gripping part and the second gripping part and electrically connecting them.
The first gripping portion for gripping the connection electrode portion and the second gripping portion for gripping the outer electrode layer grip the one of the connection electrode portion or the outer electrode layer being gripped that has a higher surface strength. A fuel cell stack characterized by having a strong gripping force.   The first gripping portion grips the connection electrode portion by extending along the periphery of the connection electrode portion, and the second gripping portion grips the outer electrode layer by extending along the periphery of the outer electrode layer. 2. The fuel cell stack according to claim 1, wherein each of the first gripping portion and the second gripping portion is configured to have a longer length extending around a portion having a stronger gripping force.   The first gripping portion grips the connection electrode portion by extending along the periphery of the connection electrode portion, and the second gripping portion grips the outer electrode layer by extending along the periphery of the outer electrode layer. The fuel cell stack according to claim 1, wherein the first grip portion and the second grip portion have different widths so as to obtain a predetermined grip force.   4. The fuel cell stack according to claim 2, wherein the first grip portion and the second grip portion extend longer than a half circumference around the connection electrode portion and the outer electrode layer, respectively.   A conductive bonding agent is disposed between the first holding part and the connection electrode part and / or between the second holding part and the outer electrode layer, and the first holding part is formed by the conductive bonding agent. The fuel cell stack according to any one of claims 1 to 4, wherein the second grip portion and the fuel cell are joined.   The connection electrode portion connected to the first gripping portion includes a metal cap attached to an end portion of the fuel battery cell and connected to the inner electrode layer, and the first gripping portion is the first gripping portion. The fuel cell stack according to any one of claims 1 to 5, wherein the gripping force is stronger than the two gripping portions.

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