JP2000133286A - Solid electrolyte fuel cell unit cell and power generation module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolyte fuel cell unit cell and a power generation module capable of simplifying a unit cell structure, omitting an external steam circulation route, and connecting power leads in the reducing atmosphere. SOLUTION: This cylindrical solid electrolyte fuel cell unit cell is provided with an air electrode 1, a solid electrolyte 2 and a fuel electrode 3 in sequence from the outside, its base end section is opened, and its tip section is closed. The base end section has an opened cylindrical shape, and the unit cell is provided with a conductive fuel feed pipe 4 inserted at a gap from the fuel electrode 3 and the gas-permeable conductive felt 5 filled in the gap between the fuel electrode 3 and the fuel feed pipe 4. The fuel feed pipe 4 is provided with a fuel electrode side exhaust gas circulation port 41 opened near the base end section of a fuel electrode side exhaust gas passage, an ejector section 44 for mixing the fuel electrode side exhaust gas flowing in via the fuel electrode side exhaust gas circulation port 41 and the fuel, and fuel blowout holes 42, 43 for feeding the mixed fuel to the fuel electrode 3 via the conductive felt 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cell used in a solid oxide fuel cell (hereinafter, also referred to as "SOFC") power generation module and a solid oxide fuel cell power generation module using the cell.

[0002]

2. Description of the Related Art As solid electrolyte fuel cell units, there are a cylindrical type and a flat type. Further, the cylindrical type includes a fuel electrode, a solid electrolyte,
There are a type in which an air electrode is arranged, and a type in which an air electrode, a solid electrolyte, and a fuel electrode are arranged in this order from the outside.

A cylindrical cell in which an air electrode, a solid electrolyte, and a fuel electrode are arranged in this order from the outside has advantages such as excellent fuel reforming performance and a simple electrode structure as described in detail below. , As shown in FIG.
A cylindrical air electrode 51, a solid electrolyte 52, and a fuel electrode 53 are coaxially stacked, and a number of pores are provided inside the fuel electrode 53 to supply natural gas and water vapor to the fuel electrode 53. A conductive tube 54 is inserted. A conductive felt 5 is provided between the conductive tube 54 and the fuel electrode 53.
5 and the anode 53 and the conductive tube 54
And are electrically connected. Air electrode 5 for cell anode
1. A conductive tube 54 is used for the cathode.

The conductive tube 54 is supplied with natural gas on the inside and steam on the outside. The natural gas and water vapor supplied to the conductive tube 54 are blown outward from many pores of the conductive tube 54 and enter the conductive felt 55. Here, natural gas (mainly composed of methane) and steam react as follows to be reformed into fuel that contributes to the cell reaction.

CH ₄ + H ₂ O → 3H ₂ + CO−49.27 kcal (reaction formula A) CO + H ₂ O → H ₂ + CO ₂ +9.83 kcal (reaction formula B) Can be expressed as follows.

CH ₄ + 2H ₂ O → 4H ₂ + CO ₂ -39.44 kcal (reaction formula C) In the actual reforming reaction, the reaction of reaction formula A is the most in terms of chemical equilibrium, and the reaction of reaction formula B Since the reaction is not so large, the reformed gas contains carbon monoxide in addition to hydrogen.

On the other hand, air is supplied to the outside of the cell, and oxygen in the air receives electrons at the air electrode 51 and is ionized as follows.

(1/2) O ₂ + 2e ⁻ → O ^2- (Reaction Formula D) The solid electrolyte 52 is made of a solid material that allows oxide ions to pass therethrough at a predetermined operating temperature (about 1000 ° C.), for example, Yttria-stabilized zirconia or the like is used, and oxide ions generated at the air electrode 51 reach the fuel electrode 53 through the solid electrolyte 52. In the fuel electrode 53, oxide ions supplied through the solid electrolyte 52, hydrogen and carbon monoxide generated by reforming react as follows, and emit electrons.

[0009] ^{_{H 2 + O 2- → H 2}} O + 2e - ( Scheme ^{E) CO + O 2- → CO} 2 + 2e - fuel electrode by the battery reaction (Scheme F) H ₂ (Scheme E) Occurred at 53
H ₂ O (steam), CO ₂ generated by the reforming (reaction formula B) and the battery reaction of CO (reaction formula F), and H ₂ remaining unreacted are discharged out of the cell from the top of the cell. Is done. It should be noted that almost all of the fuel CO generated by the reforming contributes to the battery reaction (reaction formula F), and therefore, is hardly contained in the exhaust gas.

At the front end (top) of the cell, the steam generated by the battery reaction (reaction formulas A and B) again contributes to the reforming reaction of the fuel, so that the base end (bottom) to the front end (top) of the cell. If the water vapor is supplied uniformly between them, the water vapor becomes excessive on the distal side and insufficient on the proximal side. The base end side of the conductive tube 54 has a double structure, and by supplying steam to the outer space, the fuel concentration can be made uniform and the cell performance can be improved.

FIG. 13 shows a conventional solid oxide fuel cell power generation module using such cells.
The cell 56 is housed in a casing 57. Near the upper end (upper portion) of the casing 57, an exhaust gas separator plate 60 for separating a surplus fuel discharge zone 58 of the cell 56 and a battery reaction zone 59 ranging from near the lower end (bottom) to near the upper end (top) of the cell. Is provided.

As shown in FIG. 13, a fuel electrode side exhaust port 61 is provided at an upper portion of a casing 57.
Further, an air supply port 62 is provided on the side wall of the casing 57 immediately below the cell 56, and an air electrode side exhaust port 63 is provided immediately below the exhaust gas separator plate 60. The air that has entered through the air supply port 62 is blown upward from the air outlet of the air chamber separator plate 64.
Oxygen in the air contributes to the battery reaction in the battery reaction zone 59 and is consumed, and the remaining oxygen is discharged out of the power generation module 65 from the air electrode side exhaust port 63 together with other components in the air.

On the other hand, the natural gas and steam supplied from the natural gas supply passage 66 and the steam supply passage 67 are distributed to each cell 56 by a fuel distributor 68, reformed in each cell 56, and then subjected to a battery reaction. To contribute. Thereafter, the hydrogen not contributing to the cell reaction, the water vapor generated by the cell reaction, and the carbon dioxide generated by the reforming enter the surplus fuel discharge zone 58 from the upper end of the cell 56, and enter the casing 57 from the fuel electrode side exhaust port 61. It is discharged outside.

A part of the fuel electrode side exhaust gas is recirculated to the steam supply path 67 via a pump 69 and a flow controller 70. Since the fuel electrode side exhaust contains a large amount of pure steam, a part of the fuel electrode side exhaust is
It has been returned to 7.

The above-described conventional cell and the conventional solid oxide fuel cell power generation module using the cell have been developed as having many advantages over other types of cells and modules. The main advantages are as follows. That is, the cell structure as described above can be completely internally reformed by using nickel or the like having a high catalytic action for the conductive felt, the fuel electrode, the conductive tube for fuel supply, and the like. It is more advantageous than a structure (for example, a cell structure in which a fuel electrode, a solid electrolyte, and an air electrode are sequentially arranged from the outside).

Further, since the fuel supply conductive tube itself is used as a cathode, an interconnector is not required.
By adopting such an interconnectless structure, the effective area of the cell increases, and the output of a single cell can be greatly improved.

Further, if a part of the fuel electrode side exhaust gas is returned to the steam supply path 67 as it is, the fuel electrode side exhaust gas can be effectively used as steam required for fuel reforming. The need to keep supplying steam separately from the source can be eliminated or reduced.

[0018]

However, the conventional cell and the solid oxide fuel cell power generation module using the conventional cell have the following problems.

(1) The structure of the bottom of the cell is complicated The bottom of the conventional cell is provided with a ceramic stopper in order to prevent mixing of air and fuel. For this reason, it was necessary to process the ceramic into a shape capable of closing one end of a cylindrical shape having both open ends. In addition, it is necessary to pass a conductive tube through the center of the ceramic stopper, and the structure of the cell bottom and the manufacturing process are complicated.

In addition, since the bottom of the cell has a structure in which different materials having different coefficients of thermal expansion between the cell side wall and the plug are combined, thermal stress is particularly concentrated on the bottom of the cell, and cracks are likely to occur. there were. Also, as described above, since the steam reforming reaction involves a large endothermic effect,
When the reforming reaction is performed in a part of the fuel supply pipe, a part that is locally supercooled occurs, causing local stress on the ceramic cell and causing serious troubles such as cracks and peeling of electrodes. There was also a risk of doing so. For this reason, when a crack generated at the bottom of the cell and a gas leak accompanying the crack occur, the fuel leaked from the inside of the cell and the air flowing outside the cell react and burn, and further damage the cell by local heating. There was a problem that it would.

(2) In the conventional power generation module, the steam circulation route is outside the power generation module. In the conventional power generation module, a part of the fuel electrode side exhaust is returned to the steam supply path as it is, and the fuel electrode side exhaust is used as steam required for fuel reforming. I was using it. However, for this purpose, it was necessary to provide a steam circulation route outside the power generation module. In order to drive auxiliary equipment such as the pump 69 and the flow controller 70 required for the circulation route, motive power is required, and an energy loss has occurred correspondingly. Also,
It was difficult to control these accessories, and the structure had to be complicated when including the supply pipes for natural gas and steam. Therefore, it has been desired to develop a cell capable of effectively using a large amount of water vapor contained in the fuel electrode side exhaust and suppressing the cost of producing pure water, while eliminating the external water vapor circulation route.

(3) Electrode Connection in High Temperature Oxidizing Atmosphere When connecting an electrode (power lead assembly), it is very important to avoid an increase in contact resistance and deterioration of the electrode. However, the operating temperature of the solid oxide fuel cell power generation module was as high as about 850 ° C. to about 1050 ° C., and the surroundings of the cell were also in an oxidizing atmosphere. Therefore, in the conventional solid oxide fuel cell power generation module, materials that can be used as power leads are extremely limited (for example, platinum, gold, and the like). In addition, no matter which material is used, all the requirements such as cost, easiness of processing, conductivity and the like cannot be satisfied. Under such circumstances,
It was necessary to develop a structure in which the power lead was not easily affected by corrosion or oxidation, and to expand the range of materials that could be selected as the power lead material.

An object of the present invention is to provide a solid oxide fuel cell capable of simplifying the cell structure, omitting an external steam circulation route, and connecting a power lead in a reducing atmosphere, and a solid electrolyte fuel cell. An object of the present invention is to provide a power generation module using the same.

[0024]

A solid oxide fuel cell according to the present invention has an air electrode, a solid electrolyte, and a fuel electrode in order from the outside, a base end portion of which is open, and a tip end portion in which the air electrode extends in a radial direction. A cylindrical solid oxide fuel cell that extends inward and is closed, has a cylindrical shape with a base end opened, and has a conductive property inserted with a gap between the fuel electrode. A fuel supply pipe, and a gas-permeable conductive substance filled in a gap between the fuel electrode and the fuel supply pipe, wherein the fuel supply pipe is opened near a base end of a fuel electrode side exhaust gas flow path. A fuel electrode side exhaust gas circulation port, and an ejector unit provided near the fuel electrode side exhaust gas circulation port, for mixing fuel electrode side exhaust gas and fuel flowing through the fuel electrode side exhaust gas circulation port, The fuel mixed with the exhaust gas on the fuel electrode side by the ejector unit And a fuel blowing holes for feeding through the material to the fuel electrode.

[0025] Further, a plurality of the fuel outlet holes are provided at the tip end and / or the side surface of the fuel supply pipe, and a plurality of fuel outlet holes are provided. Preferably, it is sent to the conductive material via a hole.

[0026] It is preferable that the fuel supply system further comprises a reforming catalyst provided inside the fuel supply pipe and at least around the fuel blow-out hole for steam reforming the fuel.

Further, a solid oxide fuel cell power generation module according to the present invention is a solid oxide fuel cell power module in which a plurality of the solid oxide fuel cells described in any one of the above are arranged, and comprises a fuel electrode side exhaust gas and In order to prevent mixing of the exhaust gas on the cathode side, an exhaust gas separator installed at the height where the base end of the cell is located, a fuel distributor for distributing fuel to the fuel supply pipe of the cell, and an anode for the cell anode A current collector in contact with at least a part of the cell, a cathode lead connected at one end to the current collector, and the other end positioned on the base end side of the cell and beyond the exhaust gas separator; A fuel electrode-side power lead connected to one or more fuel supply pipes at a base end side of the fuel cell and at a position beyond the exhaust gas separator; In position beyond the separator, and a connection air electrode side power lead to one or more cathode conductive leads.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a longitudinal section and a transverse section showing the structure of a solid oxide fuel cell unit according to an embodiment of the present invention.

As shown in FIG. 1, a solid electrolyte fuel cell comprises an air electrode 1, a solid electrolyte 2, and a fuel electrode 3 in that order from the outside.
And a structure in which the bottom of the cell is closed. Inside the fuel electrode 3, a fuel supply pipe 4 is inserted from the upper side of the cell. A conductive felt 5 is packed between the fuel electrode 3 and the fuel supply pipe 4,
And the fuel supply pipe 4 are electrically connected. The fuel supply pipe 4 is used for the cathode of the cell, and the air electrode 1 is used for the anode.

Two fuel electrode side exhaust gas circulation ports 41 are provided on the upper side of the cell of the fuel supply pipe 4, and the inside thereof constitutes an ejector section 44, which mainly contains methane injected by the fuel supply pipe 4. By injecting the fuel (natural gas or the like) at a high speed, a part of the fuel electrode side exhaust gas containing abundant water vapor is drawn into the fuel supply pipe 4 as an accompanying flow, and the fuel and the water vapor are mixed. Accordingly, the steam-mixed fuel in which the fuel and the steam are sufficiently mixed is sent in a uniform state from the top to the bottom of the fuel supply pipe 4. The steam mixed fuel sent into the fuel supply pipe 4 is reformed by the porous reforming catalyst 6 provided inside the fuel supply pipe 4 (reaction formulas A to C), and hydrogen contributing to the fuel cell reaction And a gas rich in carbon monoxide. The fuel reformed by the reforming catalyst 6 is supplied to a tip fuel outlet 42 provided at the tip of the fuel supply pipe 4 and a plurality of fuel outlets 43 provided at the side surface.
To the conductive felt 5 through which is further modified,
Hydrogen and carbon monoxide are produced.

On the other hand, air containing oxygen flows outside the air electrode 1, and oxygen in the air receives and ionizes electrons (reaction formula D), and oxygen ions permeate through the solid electrolyte 2. The fuel electrode 3 is reached. At the fuel electrode 3, oxide ions react with hydrogen and carbon monoxide in the conductive felt 5 while emitting electrons (reaction formulas E and F). Water vapor and carbon dioxide generated by this reaction are converted into conductive felt 5
It flows toward the upper part of the cell. Then, the steam generated by the reaction formula E again contributes to the reforming reaction in the conductive felt 5 (reaction formulas A to C).

On the upper part of the cell, an exhaust gas separator plate 11
Is provided, and the steam or the like that has flowed out of the conductive felt 5 is released as fuel electrode side exhaust gas without being mixed with air. A part of the fuel electrode side exhaust gas enters the fuel supply pipe 4 via the fuel electrode side exhaust gas circulation port 41, and is mixed with the fuel again by the ejector unit 44 as steam for reforming and circulated.

Here, as the air electrode 1, a conventionally used material can be used, and for example, strontium-added lanthanum manganite or the like can be used. Further, as the solid electrolyte 2, for example, yttria-stabilized zirconia or the like can be used. As the fuel electrode 3, it is preferable to use a material having a catalytic function for fuel reforming such as natural gas. For example, nickel zirconia cermet or the like can be used. The fuel supply pipe 4 must be made of a material having high conductivity and having sufficient strength against the internal fuel gas pressure even at a high temperature of 1000 ° C., and is preferably made of a metal such as nickel, copper, stainless steel, and inconel. It is preferable to use a material. As the reforming catalyst 6, a porous material suitable for a reforming reaction can be used. For example, nickel-supported alumina or the like can be used.

In consideration of workability and the like as the cell shape, the cell length (the length in the longitudinal direction of the air electrode) is 20 to 1
70 cm, and the diameter of the cell (air electrode 1
Is preferably 10 to 30 mm. Further, the thickness of the air electrode 1 is preferably 1 to 4 mm, the thickness of the solid electrolyte 2 is preferably 10 to 100 μm, and the thickness of the fuel electrode 3 is 20 to 500 μm. Is preferable, and the thickness of the conductive felt 5 is 0.1 mm.
The diameter of the fuel supply pipe 4 is preferably 5 to 3 mm, and the diameter of the fuel supply pipe 4 is preferably 8 to 27 mm.
Is preferably 0.5 to 3 mm, and the thickness of the reforming catalyst 6 is preferably 20 to 1000 μm.

Next, the fuel supply pipe 4 will be described in more detail. FIG. 2 is a diagram showing a side surface and a longitudinal section showing the structure of the fuel supply pipe 4.

As shown in FIG. 2, the inside of the fuel supply pipe 4 is made hollow, and the inside of the upper part of the cell is made into a nozzle shape. A fuel electrode side exhaust gas circulation port 41 is provided near the tip of the nozzle shape, and an ejector section 44 is formed. Further, a tip fuel outlet hole 42 having a diameter of 0.1 to 2 mm is provided at the tip of the fuel supply pipe 4 so as to evenly distribute the fuel on the surface of the fuel electrode 3, and a spiral shape is provided on a side surface thereof. A plurality of fuel outlet holes 43 having a diameter of 0.2 to 2 mm are provided. In addition, the fuel blowing hole 43
The fuel supply pipe 4 is bored at a predetermined angle toward the upper part of the cell, and the fuel (especially, the fuel at the bottom of the cell) ejected from the fuel outlet 43 does not stay in the cell, and the cell smoothly flows. So that it is exhausted outside.

The size, number, and position of the fuel outlet holes 42 and the size, number, position, and inclination angle of the fuel outlet holes 43 are not particularly limited to the above examples, and may be variously changed according to the use conditions and the like. It is also possible to provide only the side fuel discharge holes without providing the front end fuel discharge holes. Further, the number, shape, and the like of the fuel electrode side exhaust gas circulation ports 41 are not particularly limited to the above example, and various changes can be made according to the use conditions and the like.

The fuel gas is, for example, about 0.5 to 3 kg / cm ²
The fuel is injected from the ejector section 44 at a pressure of about G, and the fuel is ejected, so that the pressure near the fuel electrode side exhaust gas circulation port 41 becomes a negative pressure. It is drawn into the fuel supply pipe 4. The fuel and steam mixed by such an ejector effect are sent to the reforming catalyst 6, and most of the steam reforming reaction can be performed by the reforming catalyst 6. Here, since the fuel supply pipe 4 is made of a metal having high thermal conductivity such as nickel, the temperature change generated locally by the endothermic effect of the steam reforming reaction in the reforming catalyst 6 is efficiently absorbed. And the temperature inside the cell can be maintained in a well-balanced manner. The reformed fuel is uniformly sent from the tip fuel outlet 42 and the fuel outlet 43 to the entire conductive felt 5 to be completely reformed.

By the above-described reforming operation, even if a steam reforming reaction, which is an endothermic reaction, is performed, supercooling is not locally performed, so that stress is not locally applied to the ceramic cell. Also, no serious troubles such as generation of cracks and peeling of the electrodes are generated. In addition, since most of the steam reforming reaction, which is an endothermic reaction, is performed inside the fuel supply pipe 4, the solid electrolyte 2 disposed outside the fuel supply pipe 4 via the conductive felt 5 and the fuel electrode 3 has a low temperature. The cell performance is not reduced due to the decrease in the current. Further, heat required for the reforming reaction is also sufficiently supplied by Joule heat generated when an electric current passes through the cell, and sufficient fuel contributing to the battery reaction can be obtained.

The reformed fuel is used in the cell reaction at the fuel electrode 3, and the fuel electrode side exhaust gas containing water vapor after the cell reaction passes through the conductive felt 5 and the fuel electrode side exhaust gas circulation port 4.
The water vapor is circulated from the suction port 1. Here, since the exhaust gas separator plate 11 is attached to the upper end of the cell, only the fuel electrode side exhaust gas can be used.
1, the air electrode side exhaust gas does not pass around the fuel electrode side exhaust gas circulation port 41. Therefore, only the fuel electrode side exhaust gas is sucked from the fuel electrode side exhaust gas circulation port 41,
Without providing a fuel electrode side exhaust gas circulation route outside,
The water vapor in the fuel electrode side exhaust gas can be effectively used.

FIGS. 3 to 8 show an example of inter-cell connection when the solid oxide fuel cell according to the present invention is used. As shown in FIG. 3, the cathode current is
It is taken out from the cathode current collector 21 in close contact with the air electrode 1 of the cell through the cathode lead 22. In order to enhance the current collecting effect on the air electrode 1, a current collecting auxiliary agent 23 is provided between the air electrode 1 and the cathode current collector 21, and a collector having a width of several millimeters to several tens of millimeters is further provided around the air electrode 1 at regular intervals. It is preferable that the electric auxiliary ring 24 is coated. In the embodiment of FIG. 3, the cathode current collector 21 is formed by coating a fine wire of a highly conductive metal such as copper or nickel with platinum to prevent oxidation. Uses platinum paste.

Since a large amount of current flows through the cathode current collector 21 at the top of the cell and is small at the bottom of the cell, the width of both the cathode current collector 21 and the current collection aid 23 can be reduced toward the bottom. By doing so, the amount of material used can be reduced. The cathode lead may extend the cathode current collector 21 and preferably has flexibility such as a stranded wire structure to withstand thermal stress.

As shown in FIG. 4, a plurality of cells are connected to each other via a cathode current collector 21 in the vertical direction and via a cathode spacer 25 in the horizontal direction. , Constitute one bundle. Cathode spacer 2
5 extends to a position slightly lower than the upper end of the cell so as to form a gap above the cell so that air flowing between the cells is discharged. The material of the cathode spacer 25 is preferably the same as that of the air electrode 1 of the cell, and may not be electrically fixed.

FIG. 5 shows an example of the bundle structure.
Here, a bundle structure in which a total of six cells are connected, two in the vertical direction and three in the horizontal direction, is shown. Air is supplied to the cell through holes in the bottom air chamber separator plate 26 and rises up the cell along the outer cathode. The air electrode side exhaust gas and the fuel electrode side exhaust gas coming out of the inside of the cell are separated by the exhaust gas separator plate 11 so as not to be mixed and burned. The exhaust gas separator plate 11 is provided with a through hole 27 through which a cathode lead is passed.

A bundle spacer 28 is provided between the bundles to electrically insulate the bundles from each other, and a gap is provided between the bundles and the exhaust gas separator 11 so that the air exhaust gas passes through the bundle. . Accordingly, as shown in FIG. 6, the exhaust gas on the cathode side between the cells is bundled with the bundle spacer 2 in the lateral direction on the paper of FIG.
From the upper part of the cathode spacer 25, it is discharged vertically from the upper part of the cathode spacer 25.

FIG. 6 is a plan view showing a case where four sets of the bundles shown in FIG. 5 are connected in the vertical direction in the figure to form a stack. Six cells connected in parallel as described above constitute each bundle. There is a bundle spacer 28 between each bundle, and in this state, the bundles 1 to 4 are insulated from each other.

FIG. 7 shows how to take out the electrodes from the bundle. From the fuel electrode (cathode) side, an electrode is taken out from the fuel supply pipe 4 via the fuel electrode side power lead 29. On the air electrode (anode) side, an electrode is taken out from the cathode extraction lead via the air electrode side power lead 30. By connecting the fuel electrode side power lead 29 to the six fuel supply pipes 4, the cathodes of the cells are connected in parallel and become equipotential. In addition, by connecting the three cathode lead-out leads 22 by the air electrode-side power lead 30, the anodes of the cells are also connected in parallel and become equipotential.

Each fuel supply pipe 4 and fuel electrode side power lead 2
9, and the cathode lead 22 and the air electrode side power lead 30 are firmly fixed by welding, bolting, or the like so as not to increase the contact resistance. It is desirable that each power lead has flexibility by using a stranded wire structure or the like.

The electric connection between the bundles is performed by connecting the air electrode side power lead 30 and the fuel electrode side power lead 29 of the adjacent bundle by welding or bolting as shown in FIG. In this way, the bundles are electrically connected in series. The connection of the power lead is performed after the cell is covered with the exhaust gas separator plate 11.

FIG. 9 shows an example of an assembly having a stack structure. This is obtained by connecting four bundles shown in FIG. 5 in series in the vertical direction. The fuel is sent from the fuel distributor 31 through the flexible insulating joint 32 and the fuel supply pipe 4 to the inside of the cell. The stacks are partitioned by a partition board 33. For the sake of clarity, the air electrode side power lead and the fuel electrode side power lead (power lead assembly) are omitted from this drawing.

FIG. 10 shows a flexible insulating joint 3.
2 shows the connection between the fuel supply pipe 2 and the fuel supply pipe 4 in an enlarged manner. Fuel supply pipe 4 and fuel distributor 31
Are connected by a flexible insulating joint 32. As shown in FIG. 10, the flexible insulating joints 32 can be connected to each other by screwing. If the flexible insulating joint 32 has a flexible structure, even if the cells and the power generation module have different thermal stresses and different expansion coefficients, the sliding caused by the differences can be absorbed. The flexible insulating joint 32 is made of an insulating material such as ceramics or Teflon, and is connected to the fuel supply pipe 4 and the fuel distributor 31.
Can be electrically isolated from each other.

FIG. 11 shows an embodiment of the power generation module constructed by further connecting the stack shown in FIG. 9 in series.
Shown in In the power generation module, the air chamber 3
4. A battery reaction chamber 35, a fuel electrode exhaust gas chamber 36, and a fuel distributor 31 are provided. Air chamber 34
The cell reaction chamber 35 is partitioned by the air chamber separator plate 26, and the cell reaction chamber 35 and the fuel electrode exhaust gas chamber 36 are partitioned by the exhaust gas separator plate 11. Further, a top plate 37 for supporting the fuel distributor 31 is attached between the fuel distributor 31 and the fuel electrode exhaust gas chamber 36.

The air entering the air chamber 34 is blown upward from a hole provided in the air chamber separator plate 26,
After contributing to the battery reaction in the battery reaction chamber 35, the gas is discharged as the air electrode side exhaust gas. On the other hand, a fuel such as natural gas is distributed to each cell by a fuel distributor 31, supplied to a fuel supply pipe 4 of each cell via a flexible insulating joint 32, and enters a battery reaction chamber 35. After the fuel contributes to the reforming and the cell reaction in the cell reaction chamber 35, the fuel is discharged as the fuel electrode side exhaust gas in the fuel electrode exhaust gas chamber 3
Enter 6. Part of this is sucked from the fuel electrode side exhaust gas circulation path 41 and again contributes to the reforming reaction. Other fuel electrode side exhaust gas is discharged out of the fuel electrode exhaust gas chamber 36.

Between the anode exhaust gas chamber 36 and the cell reaction chamber 35, the anode exhaust gas chamber 36 is controlled by differential pressure control.
And the gas pressure difference between the battery reaction chamber 35 and the battery reaction chamber 35 are preferably eliminated. By eliminating the pressure difference, mixed combustion due to gas leakage from between the exhaust gas separator plate 11 and the cell can be suppressed, and a special seal between the exhaust gas separator plate 11 and the upper part of the cell can be eliminated. Further, the flammable gas in the fuel-electrode-side exhaust gas that has risen to the upper part of the cell is almost consumed by the battery reaction, so that a slight leak is allowed.

In the above description, a power generation module in which a plurality of solid oxide fuel cells are arranged so that the front end of the cell faces downward is explained. In consideration of drainage in the cell at the time,
The cells may be arranged such that the base ends of the cells face downward.

[0056]

The cell used in the solid oxide fuel cell power generation module according to the present invention has a structure in which the bottom of the cell can be manufactured by extrusion, so that a ceramic stopper with strict dimensions is separately manufactured. No need to install. Further, since the structure at the bottom of the cell is a structure in which thermal stress is unlikely to be concentrated at one location, it is possible to solve the problem of cracks and gas leakage accompanying the cracks.

In the solid oxide fuel cell power generation module according to the present invention, the steam is circulated in the cell utilizing the ejector effect. Therefore, there is no need to provide a steam circulation route outside the power generation module, and the steam circulation route is not required. Auxiliary equipment, such as a pump and a flow regulator, used in the above-mentioned method are not required. As a result, energy loss can be reduced, and control of the entire power generation module becomes easy.

The cell used in the solid oxide fuel cell power generation module according to the present invention can be connected to a power lead in an anode exhaust gas chamber. The fuel electrode exhaust gas chamber is in a reducing atmosphere. If the power leads are connected in such a reducing atmosphere, the power leads are less susceptible to corrosion and oxidation. As a result, the range of materials that can be selected as the power lead material is expanded, and the power lead can be formed of a material other than expensive platinum or the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing a longitudinal section and a transverse section showing the structure of a solid oxide fuel cell unit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a side view and a longitudinal section showing a structure of a fuel supply pipe shown in FIG. 1;

FIG. 3 is a perspective view showing a current collecting structure of an air electrode of the cell according to the present invention.

FIG. 4 is a plan view showing the connection of the air electrode of the cell according to the present invention.

FIG. 5 is a perspective view showing an example of a cell bundle structure according to the present invention.

FIG. 6 is a plan view showing a stack of the bundle structure shown in FIG. 5;

FIG. 7 is a perspective view showing an example of a power lead connection of a cell according to the present invention.

FIG. 8 is a perspective view showing an example of a power lead connection of a cell according to the present invention.

FIG. 9 is a perspective view showing an example of a cell stack structure according to the present invention.

FIG. 10 is an enlarged view showing a connection between a flexible insulating joint and a fuel supply pipe used in the power generation module according to the present invention.

11 is a diagram showing one embodiment of a power generation module configured by further connecting the stack shown in FIG. 9 in series.

FIG. 12 is a diagram showing a vertical section and a VV line section showing a cell structure of a conventional solid oxide fuel cell.

FIG. 13 is a diagram showing a solid oxide fuel cell power generation module using a conventional cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air electrode 2 Solid electrolyte 3 Fuel electrode 4 Fuel supply pipe 5 Conductive felt 6 Reforming catalyst 21 Cathode current collector 22 Cathode extraction lead 23 Current collection auxiliary agent 24 Current collection auxiliary ring 25 Cathode spacer 29 Fuel electrode side power lead 30 Air electrode side power lead 32 Flexible insulation joint 34 Air chamber 35 Battery reaction chamber 36 Fuel electrode exhaust gas chamber 41 Fuel electrode side exhaust gas circulation port 42 Tip fuel outlet hole 43 Fuel outlet hole 44 Ejector unit

Claims (4)

[Claims] 1. A cylindrical solid electrolyte fuel having an air electrode, a solid electrolyte, and a fuel electrode in order from the outside, a base end portion being open, and a front end portion being closed by extending the air electrode radially inward. A battery cell, comprising: a cylindrical fuel cell having an open base end; a conductive fuel supply pipe inserted with a gap between the fuel electrode and the fuel electrode; A gas-permeable conductive material filled in the gap, wherein the fuel supply pipe has a fuel electrode-side exhaust gas circulation opening that is open near the base end of the fuel electrode-side exhaust gas flow path, and the fuel electrode-side exhaust gas circulation An ejector section provided near the port, for mixing fuel and exhaust gas flowing through the anode-side exhaust gas circulation port, and a fuel mixed with fuel electrode-side exhaust gas by the ejector section. Blow-out hole for sending to the anode through a permeable material A solid oxide fuel cell comprising: 2. The fuel supply hole is provided in plural at a tip end and / or a side surface of the fuel supply pipe, and the fuel mixed with fuel electrode side exhaust gas by the ejector unit is provided with the plurality of fuel supply holes. The solid oxide fuel cell according to claim 1, which is sent to the conductive substance through a hole. 3. The solid oxide fuel cell according to claim 1, further comprising a reforming catalyst provided inside the fuel supply pipe and at least around the fuel outlet, for reforming the fuel with steam. cell. 4. A solid oxide fuel cell power generation module in which a plurality of solid oxide fuel cells according to claim 1 are arranged, wherein a fuel electrode side exhaust gas and an air electrode side exhaust gas are mixed. To prevent this, an exhaust gas separator mounted at the height where the base end of the cell is located, a fuel distributor that distributes fuel to the fuel supply pipe of the cell, and at least part of the anode of the cell A cathode lead connected at one end to the current collector, the other end at the base end side of the cell and located beyond the exhaust gas separator, and at the base end side of the cell; A fuel electrode side power lead connected to one or more fuel supply pipes at a position beyond the exhaust gas separator; and 1 or 2 at a base end side of the cell and at a position beyond the exhaust gas separator. A solid oxide fuel cell power generation module including the cathode lead and the air electrode side power lead connected to the cathode lead.