JP5491079B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system that obtains electric energy by supplying fuel gas and oxidant gas to a fuel cell in which power generation cells are stacked.

  Fuel cell systems that convert chemical energy of fuels such as hydrogen and methanol into electrical energy are generally arranged so that the electrolyte layer is sandwiched between the porous fuel electrode (anode) and air electrode (cathode) from both sides. A fuel cell in which a plurality of power generation cells are stacked. Also, inside the fuel cell stack, a fuel gas composed of hydrogen-containing gas obtained by reforming pure hydrogen or hydrocarbon fuel is supplied to the fuel electrode, or an oxidant gas such as oxygen or air is supplied to the air electrode. Gas passages are provided (see Patent Document 1).

  In such a fuel cell system, oxygen in the oxidant gas supplied to the air electrode side at a predetermined temperature is ionized at the air electrode or at the boundary between the air electrode and the electrolyte layer, so that the electrolyte The oxygen ions move toward the fuel electrode through the layer, and the oxygen ions react with the fuel gas in the fuel electrode (power generation reaction). Electrons generated by this power generation reaction are taken out as electromotive force.

JP 2008-204946 A

  However, in the fuel cell system described in Patent Document 1, when fixing a plurality of stacked power generation cells, a clamping plate larger than the power generation cell is superimposed on both ends in the stacking direction of the plurality of power generation cells, A plurality of power generation cells are fastened and fixed in the stacking direction by inserting bolts extending along the stacking direction around the power generation cells into both fastening plates and fastening the bolt insertion ends with nuts. Further, a part of a gas passage (a gas manifold in Patent Document 1) for supplying fuel gas and oxidant gas to each power generation cell is formed so as to penetrate in the stacking direction of the plurality of power generation cells in the fuel cell.

  Therefore, for example, if the electrode area such as the fuel electrode or the air electrode in the power generation cell is increased for the purpose of improving the power generation efficiency, the power generation cell comes into contact with a fastening mechanism including a bolt and a nut, a gas passage, etc. There has been a problem that short circuit and gas pressure loss become high.

  Therefore, in order to deal with such problems, for example, it is conceivable to dispose the fastening mechanism and the gas passage greatly apart from the cell main body. May be restricted, or it may be difficult to maintain the operating temperature at a high temperature, which may cause problems such as an increase in operating cost and a decrease in power generation efficiency.

  Further, in order to efficiently generate the power generation reaction of the fuel cell and increase the power generation efficiency, it is necessary to efficiently supply a high-temperature oxidant gas or fuel gas to the fuel cell. In the fuel cell system as shown in FIG. 1, if a means for heating the gas is provided in addition to the fastening mechanism and the gas passage described above, it is difficult to achieve compactness of the apparatus or the operating cost increases. There was a problem to do.

  The present invention has been made in the background of the circumstances as described above, and the problem to be solved is a compact structure, which sufficiently secures an electrode area of a power generation cell in a fuel cell, and an oxidizing agent. An object of the present invention is to provide a fuel cell system having a novel structure that can improve power generation efficiency while suppressing operating costs by efficiently heating gas or fuel gas.

(1) The invention of claim 1 made to solve such a problem,
A fuel cell formed by laminating a power generation cell composed of an electrolyte layer and an electrode layer having a substantially flat plate shape, a through-hole penetrating in the stacking direction of the fuel cell, and being inserted into the through-hole to stack the fuel cell in the stacking direction A fuel cell system having a fastening mechanism for fastening to
The fuel cell is provided with a gas flow path that supplies at least the through hole and the opening and supplies fuel gas or oxidant gas to the power generation cell,
One end of the fuel cell is communicated with the gas flow path through the opening, and an external communication path for introducing the fuel gas or the oxidant gas into the gas flow path from the outside is provided.
At least a portion near the opening of the through hole in the fastening mechanism is fixed to an end of a fixing member that is inserted into the through hole and protrudes from the fuel cell, thereby recovering exhaust heat of the fuel cell. Configured as preheating means for heating the fuel gas or the oxidant gas before being introduced into the fuel cell ,
The other end of the external communication path is opened in a direction orthogonal to the stacking direction in the fuel cell .

  In such a fuel cell system of the present invention, the preheating means for heating the fuel gas or the oxidant gas before supplying the fuel cell using the exhaust heat of the fuel cell is provided, so that the gas is heated. It is possible to efficiently generate a power generation reaction of the fuel cell by supplying high-temperature fuel gas or oxidant gas to the fuel cell while suppressing the operation cost of the fuel cell.

  In addition, the preheating means is configured as a part of the fastening mechanism, and the gas flow path of the fuel cell and the through hole into which the fastening mechanism is inserted share at least the opening, so that the fuel cell and thus the fuel cell system are In addition to being compact, the electrode area of the power generation cell can be reduced by reducing the space for any two of the fastening mechanism, the gas flow path, and the preheating means in the fuel cell system. Largely secured.

Therefore, according to the fuel cell system of the present invention, the power generation performance is effectively exhibited with a compact structure and the operation cost is suppressed.
The other end of the external communication path opens in a direction orthogonal to the stacking direction of the power generation cells in the fuel cell. For this reason, the heat receiving area for receiving the exhaust heat from the fuel cell in the external communication path is surely ensured and the fuel gas or the oxidant gas can be heated more efficiently.
In the present invention, the substantially flat plate shape of the electrolyte layer and the electrode layer includes a flat plate shape, and has small unevenness and curved portions, but has the same functions and effects as the flat plate shape. Includes a generally flat plate shape that can be considered.

(2) The invention of claim 2
Wherein the fastening mechanism, the fixed member, relative to the external thread portion provided on an end portion of the fixing member, and the bottomed cylindrical fixing nut screwed with the tip portion with a predetermined gap between said fixed member , consists of,
The preheating means included in the fastening mechanism includes a distal end portion of the fixing member and the fixing nut.

  Thereby, the preheating means is realized with a simple structure. Further, for example, when the design of the preheating means is changed, it can be easily handled by replacing the fixing nuts having different shapes such as shape, size, structure and the like.

(3) The invention of claim 3 is characterized in that the fixing nut has an internal opening, and the gas flow path and the external communication path are connected via the internal opening.
That is, in the present invention, since the fuel gas or oxidant gas heated in at least a part of the external communication path is also heated in the internal opening and introduced into the gas flow path, the gas heating is not interrupted. The high-temperature gas can be stably introduced into the gas flow path, and the power generation efficiency can be further improved. Moreover, the connection mode of the external communication path with respect to the gas flow path can be easily changed by changing the setting position of the internal opening.

(4) The invention of claim 4 is characterized in that the internal opening is open to a surface extending in parallel with the stacking direction in the fuel cell.
As a result, at least a connection portion with the internal opening in the external communication path is arranged in a direction orthogonal to the stacking direction of the fuel cells, and a large heat receiving area for receiving heat exhausted from the fuel cell is secured in the external communication path. It becomes easy to be done. As a result, the fuel gas or oxidant gas is heated more efficiently.

(5) The invention of claim 5 includes a power generation assisting member for assisting power generation of the fuel cell, and the power generation assisting member is disposed adjacent to the fuel cell in an electrically insulated state. It is characterized by being.

In such a fuel cell system of the present invention, the power generation efficiency is further improved by providing the power generation auxiliary member that assists the power generation of the fuel cell.
Here, assisting the power generation of the fuel cell means heating the fuel cell, the fuel gas, and the oxidant gas in order to efficiently generate a power generation reaction by supplying the fuel gas and the oxidant gas to the power generation cell. It means to suppress heat dissipation. That is, the power generation auxiliary member generates, for example, a heat exchanger that heats the oxidant gas, a vaporizer that generates steam necessary for generating hydrogen-containing gas used for power generation by steam reforming, and reformed gas. A reformer that performs heat insulation and a heat insulating member that suppresses heat dissipation are employed.

  That is, in the fuel cell system of the present invention, since the power generation assisting member is disposed adjacent to the fuel cell, the exhaust heat of the fuel cell is actively used to flow through the power generation assisting member, and thus the power generation assisting member. Heating the fuel gas or oxidant gas or suppressing the diffusion of the exhaust heat of the fuel cell is effectively realized, and as a result, the power generation efficiency is further improved.

1 is an explanatory model diagram schematically showing a fuel cell system as one embodiment of the present invention. The front view of the solid oxide fuel cell which comprises a part of the fuel cell system. FIG. 2 is a plan view of the solid oxide fuel cell. The perspective view which shows the principal part of the solid oxide fuel cell. The longitudinal cross-sectional explanatory drawing which shows roughly the single cell which comprises some solid oxide fuel cells. The longitudinal cross-sectional explanatory drawing which shows the same solid oxide form fuel cell roughly. The perspective view which expands and shows the fixing nut which comprises some fuel cell systems. The longitudinal cross-sectional view which expands and shows the principal part of the fuel cell system. IX-IX sectional drawing of FIG. FIG. 4 is a longitudinal sectional explanatory view schematically showing a solid oxide fuel cell in a fuel cell system as another embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings.
First, FIG. 1 schematically shows a fuel cell system 10 as an embodiment of the present invention. The fuel cell system 10 includes a solid oxide fuel cell 12 as a fuel cell, a fuel gas supply member, an oxidant gas supply member, a heating member, a power generation auxiliary member 14, a power conditioner 16, and the like. Yes.

  Although the detailed structure of the solid oxide fuel cell 12 will be described later, the solid oxide fuel cell 12 has a substantially rectangular block shape as shown in FIGS. The battery system 10 is housed and disposed in a heat insulating container 18 made of a heat insulating material constituting a part of the battery system 10. The heat insulating container 18 accommodates and arranges a heating burner 20. Air and fuel are sent from the outside of the heat insulating container 18 to the heating burner 20, and solid oxidation is performed using the proportional valve 22, the electromagnetic valve 24, and the air blower 26. The solid oxide fuel cell 12 is heated in the heat insulating container 18 while adjusting the amount of air optimal for the heating efficiency of the physical fuel cell 12. In short, the heating member includes the heating burner 20, the proportional valve 22, the electromagnetic valve 24, and the air blower 26.

  In particular, in the present embodiment, when the solid oxide fuel cell 12 is accommodated in the heat insulating container 18, the vaporizer 28 and the heat exchanger 30 are covered with the solid oxide so as to cover the outer peripheral portion of the solid oxide fuel cell 12. The vaporizer 28 and the heat exchanger 30 are also accommodated in the heat insulating container 18.

The carburetor 28 has a housing structure having a shape along a part of the peripheral wall portion of the solid oxide fuel cell 12.
Further, the vaporizer 28 is connected to a pure water tank 32 and a supply pump 34 provided outside the heat insulating container 18 through a water supply pipe 36, and the water in the pure water tank 32 is supplied to the supply pump 34. To the inside of the vaporizer 28 through the water supply line 36. And in the vaporizer | carburetor 28 heated by the heating burner 20, water is heated and becomes water vapor | steam.

  Further, the vaporizer 28 and a raw material gas tank, an electromagnetic valve 38 and a booster pump 40 (not shown) provided outside the heat insulating container 18 are connected through a raw material gas supply pipe 42, and the electromagnetic valve 38 and the booster pump 40 are connected. The raw material gas is sent into the vaporizer 28 while adjusting the discharge amount of the raw material gas into the vaporizer 28. The source gas of the present embodiment is, for example, city gas containing hydrocarbons such as methane, LPG, or the like.

Furthermore, a fuel gas supply line 44 is provided on the outer wall portion of the vaporizer 28 and connected to the solid oxide fuel cell 12.
As a result, the raw material gas and water vapor are mixed in the vaporizer 28 to generate a fuel gas, and the fuel gas is reformed into a hydrogen-containing gas in a reforming layer 90 described later through the fuel gas supply pipe 44. , And supplied to the solid oxide fuel cell 12. That is, the fuel gas supply member of the fuel cell system 10 includes the vaporizer 28, the reformed layer 90, the pure water tank 32, the supply pump 34, the water supply line 36, the electromagnetic valve 38, the booster pump 40, and the raw material gas supply line. 42, a fuel gas supply pipe 44 is included.

  On the other hand, the heat exchanger 30 includes a first heat exchanger 30 a disposed along a part of the peripheral wall portion of the solid oxide fuel cell 12 and a second heat exchanger 30 disposed above the solid oxide fuel cell 12. The heat exchanger 30b is included. Further, the heat exchanger 30 is attached inside or around the oxidant gas supply pipe 46. One end of the oxidant gas supply line 46 is connected to the air blower 48, and the other end of the oxidant gas supply line 46 is connected to the solid oxide fuel cell 12.

  Accordingly, an oxidant gas such as oxygen or air is supplied to the solid oxide fuel cell 12 using the air blower 48 while being heated by the heat exchanger 30. That is, the oxidant gas supply member of the fuel cell system 10 includes the heat exchanger 30, the oxidant gas supply line 46, and the air blower 48.

  Therefore, the solid oxide fuel cell 12 is heated by the heating burner 20 in the heat insulating container 18 and is supplied from the fuel gas supply line 44 to the solid oxide fuel cell 12 under a medium to high temperature state. The fuel gas is supplied with the oxidant gas from the oxidant gas supply line 46, and a power generation reaction occurs in the solid oxide fuel cell 12. Electrons generated by the power generation reaction are converted into the power conditioner 16. The voltage is transformed through an electric current or converted into an alternating current so as to be taken out as an electromotive force.

  Further, in the fuel cell system 10 of the present embodiment, the exhaust gas pipe 50 is connected to the solid oxide fuel cell 12 via a fixing nut 106b described later, and the open end of the exhaust gas pipe 50 is used. However, it opens to the outside of the heat insulating container 18 of the fuel cell system 10. As a result, the exhaust gas generated with the supply of the oxidant gas and the fuel gas to the solid oxide fuel cell 12 is heated in the first heat exchanger 30a, and the heat insulating container 18 passes through the exhaust gas conduit 50. It is designed to be discharged outside.

  In the solid oxide fuel cell 12 of this embodiment, a plurality of single cells 52 (hereinafter also simply referred to as “cells 52”) as power generation cells are stacked in the thickness direction (up and down in FIGS. 2 and 4). The power generation stack 54 is configured.

  As shown schematically in FIG. 5, the cell 52 has a substantially flat plate shape as a whole, and an air electrode (cathode) as one electrode layer on both sides of the solid electrolyte body 56 as an electrolyte layer. 58 and a cell body 62 to which a fuel electrode (anode) 60 as the other electrode layer is fixed. As the solid electrolyte body 56, for example, YSZ, ScSZ, SDC, GDC, perovskite oxide, or the like is employed. Further, for example, the air electrode 58 is made of perovskite oxide, various noble metals, cermet of noble metal and ceramic, and the fuel electrode 60 is made of Ni, cermet of Ni and ceramic, or the like.

A separator 64 is bonded to the surface of the solid electrolyte body 56 to which the air electrode 58 is fixed so as to surround the air electrode 58.
Further, a pair of interconnectors 66a and 66b having a substantially flat plate shape are disposed opposite to each other with the cell body 62 and the separator 64 interposed therebetween.

  An air electrode frame 68 and an insulating frame 70 are overlapped between the outer peripheral portion of the separator 64 and the outer peripheral portion of one interconnector 66a around the air electrode 58. Further, a fuel electrode frame 72 is interposed between the outer peripheral portion of the separator 64 and the outer peripheral portion of the other interconnector 66 b around the fuel electrode 60.

  The separator 64, the interconnector 66, the air electrode frame 68, the insulating frame 70, and the fuel electrode frame 72 are formed using a metal material or a ceramic material that is impermeable to fuel gas or oxidant gas. Further, an insulating frame 70 made of a ceramic insulating material is provided between the pair of interconnectors 66a and 66b, whereby the interconnectors 66a and 66b are insulated.

  That is, an oxidant gas supply path 74 partitioned by the separator 64, the interconnector 66a, the air electrode frame 68, and the insulating frame 70 is provided between the opposing surfaces of the cell body 62 and the separator 64 and the one interconnector 66a. ing. On the other hand, a fuel gas supply path 76 partitioned by the separator 64, the interconnector 66b, and the fuel electrode frame 72 is provided between the opposing surfaces of the cell body 62 and the separator 64 and the other interconnector 66b.

  A conductive current collector 78 made of a ceramic porous body such as LSCF or LSM, a metal felt such as nickel felt, or the like is fixed on the surface exposed to the oxidant gas supply path 74 of the interconnector 36a. Since the current collector 78 is in contact with the air electrode 58 of the cell body 62, the air electrode 58 and one interconnector 66 a are electrically connected via the current collector 78.

Further, the other interconnector 66b and the fuel electrode 60 are in direct contact with each other, whereby the other interconnector 66b and the fuel electrode 60 are electrically connected.
As schematically shown in FIG. 6, a plurality of such cells 52 are stacked in the thickness direction (up and down in FIGS. 5 and 6). In the cells 52 and 52 adjacent in the stacking direction, the interconnector 36 may be shared, or may be used independently and overlap each other. 5 and 6 are drawings schematically showing the cross-sectional shape of the cell 52 for easy understanding of the contents of the present invention, and are not drawings showing the actual cross-sectional shape. Further, FIG. 6 is not a drawing corresponding to FIGS.

  Electrode plates 80 are superimposed on both ends of the plurality of cells 52 in the stacking direction. The electrode plate 80 is electrically connected to the current collector 78 via the interconnector 66 of each cell 52 and is connected to the power conditioner 16 via a lead frame 82 provided outside the cell 52. ing.

  Further, in the fuel cell system 10 of the present embodiment, off-gas combustion layers 84 and 88 are stacked on the outer end surface of each electrode plate 80 in the power generation stack 54. The off-gas combustion layers 84 and 88 are configured to include a combustion catalyst that oxidizes CO and hydrogen in the exhaust gas after power generation, and the off-gas combustion layer 84 on one side in the stacking direction (upper in FIG. 6) CO and hydrogen that could not be processed in the off-gas combustion layer 88 on the other side in the stacking direction (lower in FIG. 6) are oxidized. An end wall portion 86 having a substantially rectangular shape outside the off-gas combustion layer 84 in the stacking direction is a wall portion at the stacking direction end of the power generation stack 54.

  Further, a reforming layer 90 is laminated on the outer end face of the off-gas combustion layer 88. The reforming layer 90 is configured to include a catalyst or the like for steam reforming a hydrocarbon raw material serving as a hydrogen source contained in the fuel gas.

  Further, the gas flow path 92 includes an off-gas combustion layer 84, an interconnector 66, an air electrode frame 68, an insulating frame 70, a separator 64, a fuel electrode frame 72, and an off-gas combustion layer 88 and a reforming layer 90 in each cell 52. It is formed penetrating in the direction. The gas channel 92 extends in the stacking direction of the power generation stack 54 with a substantially constant circular cross section.

  In particular, in the present embodiment, a total of seven gas flows including five gas passages 92 for supplying fuel gas or oxidant gas to the fuel cell 12 and two gas passages 92 for discharging exhaust gas from the combustion cell 12 are added. A path 92 is provided in the circumferential direction around the cell body 62 of each cell 52 of the power generation stack 54 at a predetermined distance in the circumferential direction. That is, two of these seven gas flow paths 92 are a first oxidant gas flow path 92a and a second dioxide gas flow path 92d for circulating the oxidant gas. Another three of the seven gas flow paths 92 are a first fuel gas flow path 92g, a second fuel gas flow path 92f, and a third fuel gas flow path 92e for circulating the fuel gas. . Furthermore, another two of the seven gas passages 92 are a first exhaust gas passage 92c and a second exhaust gas passage 92b for circulating the exhaust gas.

  In addition, the insertion hole 93 having substantially the same diameter as each gas flow path 92 and extending in parallel is formed in the same manner as the gas flow path 92. The frame 70, the separator 64, the fuel electrode frame 72, the off-gas combustion layer 88, and the reforming layer 90 are formed so as to penetrate therethrough.

  In the first and second dioxide gas flow paths 92 a and 92 d, a gas passage hole 94 that passes through the air electrode frame 68 of each cell 52 and opens to the oxidant gas supply path 74 and a gas that opens to the off-gas combustion layer 88. A through hole is provided.

  The first fuel gas channel 92g is provided with a gas through hole that opens to the reformed layer 90. The second fuel gas flow path 92f and the third fuel gas flow path 92e are connected to the fuel gas supply path 76 through the gas passage hole opened in the reformed layer 90 and the fuel electrode frame 72 of each cell 52. An open gas passage 96 is provided.

  The first and second exhaust gas passages 92b and 92c pass through the air electrode frame 68 and the fuel electrode frame 72 of each cell 52, respectively, and pass through the gas passages that open to the oxidant gas supply path 74 and the fuel gas supply path 76. Holes 98a and 98b are provided. The first exhaust gas passage 92c is provided with both off-gas combustion layers 84 and 88, and the second exhaust gas passage 92b is provided with gas through holes that open to the off-gas combustion layer 84.

  A fixing rod 100 as a fixing member is inserted into each of the seven gas flow paths 92 and the insertion holes 93. The fixed rod 100 has a substantially columnar shape having an axial dimension larger than that of the gas flow path 92 and the insertion hole 93 and a smaller diameter dimension, and is formed using a metal material. Further, male screw portions 102 are provided at both axial ends of the fixed rod 100.

  A fixing nut 106 is screwed into each male screw portion 102 that passes through the off-gas combustion layer 84 and the reforming layer 90 from both ends in the stacking direction of the power generation stack 54 in each fixing rod 100 and protrudes to the outside. That is, the fixing nut 106 has a substantially cup shape, and the male screw portion 102 is screwed to the female screw portion threaded on the inner peripheral surface.

  Thereby, each cell 52 of the power generation stack 54, the electrode plate 80, the off-gas combustion layers 84 and 88, and the modified layer 90 are clamped and fixed from both sides in the stacking direction. In short, the fastening mechanism that fastens and fixes the plurality of cells 52 from both sides in the stacking direction includes the fixing rod 100 and the fixing nut 106.

  Further, the through hole for inserting the fixing rod 100 into the solid oxide fuel cell 12 includes not only the insertion hole 93 but also the openings 103 on both sides in the stacking direction of the gas flow path 92 as well as the gas flow. The entire path 92 is included. Further, the opening 103 of each gas flow path 92 and the opening of the insertion hole 93 are covered with each fixing nut 106.

  In particular, in the present embodiment, the bottom portion of the fixing nut 106 and the distal end portion of the fixing rod 100 are spaced apart from each other in the axial direction inside the fixing nut 72 when the male screw portion 102 of the fixing rod 100 and the fixing nut 106 are screwed together. As a result, a gap 110 is formed between the opposed surfaces of the bottom and the tip.

  Further, a plurality of notches 104 are provided on the outer peripheral surfaces on both axial sides of each fixed rod 100 so as to be spaced apart in the circumferential direction. The notch 104 has an axial length from the axial end portion of the fixed rod 100 to the gas flow path 92 of the power generation stack 54 through the male screw portion 102, and the distal end portion (axial end portion) of the fixed rod 100. ) And the bottom of the fixing nut 106 and the gas channel 92 is opened. As a result, the gap 110 and the gas flow path 92 are communicated with each other through the notch 104. In other words, the gap 110 and the notch 104 are configured as a part of the gas flow path 92.

  Further, in each fixed rod 100 inserted through the first oxidant gas flow path 92a, the first fuel gas flow path 92g, and the second exhaust gas flow path 92b, one male screw portion in the stacking direction (upper in FIG. 6). A substantially circular internal opening 108 is provided through the peripheral wall portions of the fixing nuts 106a, 106b, and 106g fixed to the 102.

The internal opening 108, laminating direction because it is formed through the peripheral wall portion (surface) extending in parallel with, perpendicular direction perpendicular to the stacking direction of the power generating stack 54 of the power generating stack 54 in the fixed nut 106 (FIG. 6 It opens to the middle, left and right). Further, the internal opening 108 is located on the central side in the direction perpendicular to the outer peripheral edge portion of the end wall portion 86 located at the stacking direction end of the plurality of cells 52 in the power generation stack 54.

Further, as shown in FIGS. 7 to 9, a substantially cylindrical connecting tube portion 112 protrudes around the inner opening 108 in the peripheral wall portion of each of the fixing nuts 106 a, 106 b, and 106 g toward the outside in the perpendicular direction. It is installed. An external communication path 111 is formed by the inner hole of the connecting cylinder portion 112 and communicates with the gap 110 through the internal opening 108. As is clear from this, the external communication path 111 is arranged in a direction orthogonal to the stacking direction of the power generation stack 54.

  The connecting tube portion 112 of the fixing nut 106a inserted and fixed in the first oxidant gas flow path 92a is directed from the heat exchanger 30 of the oxidant gas supply line 46 in the fuel cell system 10 to the solid oxide fuel cell 12. The opening end is connected to a pipe joint (for example, manufactured by Swagelok).

  As a result, the oxidant gas such as oxygen or air is heated by the heat exchanger 30 while the oxidant gas supply pipe 46 is connected to the external communication path 111 in the connecting cylinder part 112, the internal opening 108 of the fixing nut 106a, and the gap. 110 and the notch 104 are introduced into the first oxidant gas flow path 92 a, and are further introduced into the oxidant gas supply paths 74 through the gas through holes 94 of the air electrode frames 68.

  Further, the connecting cylinder portion 112 of the fixing nut 106g inserted and fixed in the first fuel gas passage 92g is connected to the open end of the fuel gas supply pipe 44 projecting from the vaporizer 28 in the fuel cell system 10 and the piping. They are connected using joints.

  As a result, the fuel gas obtained by mixing the raw material gas and the water vapor inside the vaporizer 28 is supplied from the fuel gas supply pipe 44 to the external communication path 111 in the connecting cylinder portion 112, the internal opening 108 of the fixing nut 106g, the gap 110, It flows into the first fuel gas channel 92 g through the notch 104 and further flows into the reformed layer 90. Then, the fuel gas mainly composed of hydrocarbon raw material undergoes a reforming reaction (steam reforming) on the reformed layer 90 heated by the heating burner 20 or the like, and is converted into a fuel gas mainly composed of hydrogen. The hydrogen-based fuel gas flows into the second fuel gas flow path 92f and the third fuel gas flow path 92e, and is introduced into the fuel gas supply paths 76 through the gas through holes 96 of the fuel electrode frames 72.

  Accordingly, oxygen in the oxidant gas in the oxidant gas supply path 74 is ionized at the air electrode 58 or the boundary portion between the air electrode 58 and the solid electrolyte body 56 to become oxygen ions, and the fuel electrode 60 passes through the solid electrolyte body 56. Move towards. Such oxygen ions undergo an electrode reaction (power generation reaction) with hydrogen in the fuel gas of the fuel electrode 60 to generate electrons, and the electrons are collected from the current collector 78 through the interconnector 66, electrode plate 80, and lead frame 82. 16 is supplied as a direct current, transformed, or converted into an alternating current and supplied to an external load (not shown) as electric power.

  Further, in the first and second dioxide gas flow paths 92a and 92d, the remaining oxidant gas introduced into the oxidant gas supply paths 74 from the gas through holes 94 of the air electrode frames 68 is off-gas burned as exhaust gas. It flows into the layer 88. Further, the remaining oxidant gas and fuel gas used for the power generation reaction in each of the oxidant gas supply path 74 and the fuel gas supply path 76 are exhausted from the gas through holes 98a and 98b through the first and second exhaust gases. The gas flows into the off-gas combustion layer 88 through the flow paths 92b and 92c.

The CO in the exhaust gas in the off-gas combustion layer 88 is converted to CO ₂ by the combustion catalyst accommodated in the off-gas combustion layer 88.
The connecting cylinder portion 112 of the fixing nut 106b inserted and fixed in the second exhaust gas flow path 92b is connected to the open end of the exhaust gas conduit 50 in the fuel cell system 10 using a pipe joint. As a result, the exhaust gas mainly composed of CO ₂ in the off-gas combustion layer 88 passes from the second exhaust gas flow path 92 b through the external communication path 111 in the connecting cylinder portion 112, the internal opening 108 of the fixed nut 106 b, the gap 110, and the notch 104. The gas is introduced into the exhaust gas pipe 50 and further discharged to the outside of the heat insulating container 18.

  In particular, in the present embodiment, the exhaust gas flowing through the exhaust gas conduit 50 is discharged through the first heat exchanger 30a fixed to the power generation stack 54, so that the exhaust heat effect is enhanced. Such exhaust heat may be used, for example, for heating the oxidant or fuel gas supply lines 44 and 46, or may be used as a heat source for a domestic hot water supply system. Alternatively, the exhaust heat may be used in a so-called bottoming cycle that is used for power generation by a gas turbine or a steam turbine.

  In the fuel cell system 10 configured as described above, the oxidant gas and the fuel gas are introduced into the external communication path 111, the internal opening 108, and the gap 110 before both flow into the gas flow path 92. . The outer communicating path 111, the inner opening 108, the connecting cylinder portion 112, the fixing nut 106, and the distal end of the fixing rod 100 constituting the gap 110 are disposed on the end wall portion 86 in the stacking direction of the power generation stack 54, The exhaust heat from the solid oxide fuel cell 12 is received.

In this embodiment in particular, I'll be linking tube 112 is disposed so as to extend at right angles a direction perpendicular to the stacking direction on the end wall portion 86, a solid over the entire length of the connection tubular part 112 oxide fuel cell The exhaust heat from 12 can be received.

  Therefore, the oxidant gas and the fuel gas are effectively heated in the external communication path 111, the internal opening 108, and the gap 110 before flowing into the gas flow path 92. As a result, the high-temperature oxidant gas The fuel gas is supplied to each cell 52 through the notch 104 and the gas flow path 92, so that the power generation reaction of the fuel cell 12 occurs efficiently and excellent power generation performance can be obtained.

  As is clear from the above description, at least a part of the external communication path 111 is configured and provided around the opening 103 of the gas flow path 92 (in the vicinity of the opening) to recover the exhaust heat of the fuel cell 12. The preheating means for heating the fuel gas or the oxidant gas before being introduced into the fuel cell 12 includes the connecting cylinder portion 112, the fixing nut 106, and the distal end portion of the fixing rod 100.

  That is, since the preheating means includes a part of the fastening mechanism including the fixing nut 106 and the fixing rod 100, it is not necessary to dispose the preheating means at a different location from the fastening mechanism.

  In addition, in this embodiment, all of the through holes into which the fixing rod 100 is inserted function as the gas flow path 92 through which the fuel gas, the oxidant gas, and the exhaust gas flow. The arrangement space of any one of the flow paths 92 is substantially reduced, and a large electrode area of the cell 52 can be secured by such a reduction.

  Further, in the present embodiment, the vaporizer 28 and the heat exchanger 30 are arranged along the peripheral wall portion of the solid oxide fuel cell 12, in other words, capable of transferring heat to and from the solid oxide fuel cell 12. The fuel gas generated in the vaporizer 28 and the oxidant gas supplied to the fuel cell 12 via the heat exchanger 30 are provided in the fuel cell. The exhaust heat of 12 is used for efficient heating. As is clear from this, the power generation assisting member 14 provided adjacent to the solid oxide fuel cell 12 in the fuel cell system 10 and assisting power generation includes a vaporizer 28, a heat exchanger 30 and the like. It consists of

  Therefore, in the fuel cell system 10 of the present embodiment, the oxidant gas or the fuel gas is efficiently heated with a compact structure. As a result, the power generation efficiency is extremely advantageously improved while suppressing the operation cost.

  In the present embodiment, the exhaust gas is led to the gap 110, the internal opening 108, and the external communication path 111 from the gas flow path 92 through the notch 104 and then discharged to the outside. Similarly to the fuel gas and the oxidant gas, the exhaust gas can be heated using the exhaust heat of the fuel cell 12 in the gap 110, the internal opening 108, and the external communication path 111. Therefore, the heat utilization of the exhaust gas becomes more advantageous.

  As mentioned above, although one embodiment of the present invention has been described in detail, the present invention is not limited in any way by the specific description in the embodiment, and various changes, modifications, and modifications based on the knowledge of those skilled in the art. The present invention can be implemented in a mode with improvements and the like. Further, it goes without saying that all such embodiments are included in the scope of the present invention as long as they do not depart from the spirit of the present invention.

For example, in the above-described embodiment, by applying the present invention, the internal opening 108 penetrates the peripheral wall portion of the fixing nut 106, and on the end wall portion 86 in the stacking direction of the power generation stack 54 in the stacking direction. The connecting cylinder part 112 is arranged so as to extend in a direction orthogonal to the stacking direction while opening in the orthogonal direction .
On the other hand, as a reference example in which the same effect as that of the present invention can be obtained, the internal opening extends in the stacking direction by penetrating the bottom of the fixing nut, and the connecting tube portion extends in parallel with the stacking direction. You may arrange as follows.

  Even if the connecting cylinder portion is arranged so as to extend in parallel with the stacking direction, the gap formed between the bottom portion of the fixing nut and the tip end portion of the fixing rod is formed inside the fixing nut by the exhaust heat of the fuel cell. By being warmed, the fuel gas or the oxidant gas can be preheated.

In other words, if preheating is to be applied to the fuel gas or oxidant gas, the connecting cylinder portion constituting the external communication path is required to have an oxidant or fuel gas supply pipe arrangement form, a heating form of the pipe line, or the like. What is necessary is just to design appropriately according to the form, not only those that extend in the direction orthogonal to the stacking direction of the power generation stack as in the above embodiment , but inclined at a predetermined angle with respect to the stacking direction, It may extend parallel to the stacking direction.

  In the above-described embodiment, the connecting cylinder portion 112 is disposed on the end wall portion 86 in the stacking direction of the power generation stack 54, so that the oxidant or fuel gas preheating means is connected to the external connection in the connecting cylinder portion 112. Although it was configured to include all of the passages 111, for example, when the connecting cylinder portion extends greatly outward from the end wall portion in the stacking direction of the power generation stack, the end wall in the stacking direction in the connecting cylinder portion You may comprise including the external communication path in the part located on a part, ie, a part of external communication path.

In the above-described embodiment, the off-gas combustion layers 84 and 88 and the modified layer 90 are stacked on the power generation stack 54. However, the present invention is not limited to such a form.
That is, the power generation auxiliary members such as the offgas combustion layers 84 and 88 are not essential constituent elements. For example, only the offgas combustion layer 84 may be provided on one wall portion in the stacking direction of the power generation stack 54 or as shown in FIG. As described above, the off-gas combustion layers 84 and 88 may not be provided in the power generation stack 54.

The shape and size of the first and second dioxide gas channels 92a, 92d, the first, second and third fuel gas channels 92e, 92f, 92g, the first and second exhaust gas channels 92b, 92c, The number, structure, arrangement, etc. are appropriately changed in design according to the required inflow ratio of the oxidant gas and fuel gas, the exhaust gas exhaust efficiency, the productivity of the power generation stack 54, and the like. For example, the shape and size of the gas flow path 92 are different, or the oxidant gas flow path 92, the fuel gas flow path 92, and the exhaust gas flow path 92 are provided in a number and arrangement different from those of the above-described embodiment. (Refer to FIG. 10 etc.)
More specifically, the gas flow path 92 of the above embodiment substantially functions as a through hole by sharing all with the through hole into which the fixing rod 100 of the fastening mechanism is inserted. The passage and the through-hole can share only the opening, and other parts can be formed independently inside the power generation stack, or the opening and other parts can be partially shared It is.

  In the above embodiment, the gas flow path 92 shares all of the through holes so that both ends of the gas flow path 92 are opened on both sides in the stacking direction of the fuel cell 12. It is also possible to form the gas flow path in a non-penetrating manner in the fuel cell stacking direction by positioning the end portion that does not share the portion inside the fuel cell.

  -In the said embodiment, the hydrocarbon raw material contained in city gas, LPG, etc. is used as source gas, and solid oxidation is carried out by carrying out the steam reforming of the fuel gas which consists of this source gas and water vapor | steam through the reforming layer 90 Hydrogen required for the power generation reaction of the physical fuel cell 12 can be obtained. For example, when hydrogen is previously used as the raw material gas, as shown in FIG. It is not necessary to provide the combustion layers 84 and 88 and the modified layer 90.

  -In the said embodiment, each exhaust gas produced after each oxidizing agent gas and fuel gas are each supplied to each cell 52 is discharged | emitted collectively in the 1st and 2nd exhaust gas flow paths 92b and 92c. However, as shown in FIG. 10, for example, the first exhaust gas passage 92b ′ is used for exhausting the oxidant gas, and the second exhaust gas passage 92b ′ is used for exhausting the fuel gas (hydrogen gas). By using ', oxidant gas exhaust and fuel gas exhaust may be performed separately.

  In another embodiment shown in FIG. 10, members and parts having substantially the same structure as those of the above-described embodiment are denoted by the same reference numerals as those of the above-described embodiment, and detailed description thereof will be given. Is omitted.

  In addition, in the fuel cell system of the above embodiment, the solid oxide fuel cell 12 is employed as the fuel cell, but the polymer electrolyte fuel cell (PEFC), the phosphoric acid fuel cell (PAFC), It is of course possible to employ a molten carbonate fuel cell (MCFC) or the like.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system, 12 ... Solid oxide fuel cell, 52 ... Single cell, 54 ... Power generation stack, 92a ... First oxidant gas flow path, 92b ... Second exhaust gas flow path, 92c ... First exhaust gas Flow path, 92d ... second dioxide gas flow path, 92e ... third fuel gas flow path, 92f ... second fuel gas flow path, 92g ... first fuel gas flow path, 100 ... fixed rod, 103 ... opening, 106 ... Fixing nut, 111 ... External communication path

Claims (5)

A fuel cell formed by laminating a power generation cell composed of an electrolyte layer and an electrode layer having a substantially flat plate shape, a through-hole penetrating in the stacking direction of the fuel cell, and being inserted into the through-hole to stack the fuel cell in the stacking direction A fuel cell system having a fastening mechanism for fastening to
The fuel cell is provided with a gas flow path that supplies at least the through hole and the opening and supplies fuel gas or oxidant gas to the power generation cell,
One end of the fuel cell is communicated with the gas flow path through the opening, and an external communication path for introducing the fuel gas or the oxidant gas into the gas flow path from the outside is provided.
At least a portion near the opening of the through hole in the fastening mechanism is fixed to an end of a fixing member that is inserted into the through hole and protrudes from the fuel cell, thereby recovering exhaust heat of the fuel cell. Configured as preheating means for heating the fuel gas or the oxidant gas before being introduced into the fuel cell ,
The other end of the external communication path opens in a direction orthogonal to the stacking direction of the fuel cell. Wherein the fastening mechanism, the fixed member, relative to the external thread portion provided on an end portion of the fixing member, and the bottomed cylindrical fixing nut screwed with the tip portion with a predetermined gap between said fixed member , consists of,
2. The fuel cell system according to claim 1, wherein the preheating means included in the fastening mechanism includes a distal end portion of the fixing member and the fixing nut. 3.   The fuel cell system according to claim 2, wherein the fixing nut includes an internal opening, and the gas flow path and the external communication path are connected via the internal opening.   4. The fuel cell system according to claim 3, wherein the internal opening is opened on a surface extending in parallel with the stacking direction of the fuel cell. 5. 2. A power generation assisting member for assisting power generation of the fuel cell, wherein the power generation assisting member is disposed adjacent to the fuel cell in an electrically insulated state. 5. The fuel cell system according to any one of 4 .