JP3346784B2 - Vertical stripe cylindrical solid electrolyte fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid oxide fuel cell. More specifically, according to the present invention, an air electrode is provided outside a cylindrical porous support tube, a solid electrolyte, an interconnector, and a fuel electrode are further laminated thereon, and an oxidizing agent is provided inside the porous support tube. The present invention relates to a vertical-striped cylindrical solid electrolyte fuel cell that generates gas by flowing gas and fuel gas around a fuel electrode.

[0002]

2. Description of the Related Art A solid electrolyte fuel cell has high power generation efficiency and, when combined with a bottoming cycle as a large-scale power plant, can be expected to be capable of constructing a more efficient power generation system than conventional power plants. , Its practical use is urgent. Further, since it is expected that the generation of air polluting gas is small and the size of the system is reduced, it can be used as a distributed power source that can avoid energy loss due to long-distance power transmission adjacent to a power consumption area. Even more is better the solid electrolyte fuel cell, since the adjacent power consumption area, the heat obtained from the fuel cell can be effectively used for heating and cooling, it is to more energy efficiency can be high Mel.

Meanwhile, in the case of a vertical stripe cylindrical solid electrolyte fuel cell, a cylindrical fuel cell module having a configuration as shown in, for example, a perspective view in FIGS. 6 and 7 has been conventionally proposed. As shown in FIG. 5, each unit cell 101 has a porous air electrode 12, a dense solid electrolyte 13, a porous fuel electrode 15, and a dense interconnector 14 on a cylindrical porous support tube 11. The constituent materials are laminated in this order. As shown in FIGS. 6 and 7, the porous support tube 11
An oxidizing gas supply pipe 107 is inserted from the rear end into a cylindrical shape having a closed front end and an open rear end, and an oxidizing gas such as air is supplied to the vicinity of the front end of the closed porous support tube. I have. In addition, the cells 101, 101,
, 101, a fuel gas such as hydrogen is supplied from a fuel gas supply port 105 near the closed end of the unit cell 101, and flows along the unit cell 101. An unreacted portion of each gas burns in a space 106 provided above the unit cell 101 and is used for preheating the oxidizing gas. In the fuel cell having such a structure, it is not necessary to consider a gas seal for preventing the mixture of the fuel gas and the oxidizing gas.

Further, as shown in FIG. 7, a plurality of batteries 101 are electrically connected in series and in parallel with each other in a bundle, and are constructed as a stack (collective battery). At this time, nickel felts 104, 104,..., 104 are used to connect the cells 101, 101,.
Through the positive and negative (+) side current collectors 102 and 103, the battery is taken out of the container.

[0005] This vertical stripe cylindrical solid electrolyte fuel cell is made of only solid cell constituent materials. The air electrode and the fuel electrode are mainly made by a slurry dipping method, and the electrolyte and the interconnector are made by an electrochemical vapor deposition method. ing. Also,
6 and 7, the porous support tube 11
Since the battery has a cylindrical structure on top, it has high mechanical strength, and even if the electrolyte membrane has a thickness of 20 to 50 μm, the current density per unit area can be increased without being destroyed by thermal shock or the like. There is an advantage that the output can be improved.

[0006]

However, the vertical stripe cylindrical solid electrolyte fuel cell also has a weak point. That is, first, there is a problem in manufacturing. First, in the slurry dipping method, the porous support tube 11 is immersed in a slurry of an air electrode material or a fuel electrode material (slurried ceramics). Since the ceramic drips downward, it is difficult to form a film having a uniform thickness. Also, in the production of an electrolyte or an interconnector by an electrochemical deposition method using a metal chloride at a high temperature, the corrosion resistance of the device also becomes a problem, but it is extremely difficult to control the film thickness, especially when the area of the film to be formed is large. For example, the current manufacturing technology can only manufacture a device having a length of about 50 cm. This is because, in the conventional film forming method, the reaction is likely to occur near the supply of the raw material, and the concentration of the raw material gas becomes thinner at a distance from the supply port, so that the reaction hardly occurs. The film thickness varies depending on the thickness. From the above two points, it is difficult to reduce the length of one battery to a practical level of 1 to 2 m, and at present it is a major barrier to the practical use of solid electrolyte fuel cells. .

[0007] Even if the length of the cylindrical solid electrolyte fuel cell can be increased, the conventional oxidizing gas / fuel gas supply method requires the gas to flow as the supplied gas flows to the end of the cell. Concentration becomes low, and in the case of large-capacity batteries, there is a difference in the current value that can be extracted in the length direction on the battery surface. As a result, electrode overvoltage (voltage drop other than the battery resistance of the material) increases, and energy is effectively used. In addition, effective use of the electrode area cannot be achieved. That is, even if the length of the unit cell is increased in order to increase the output density per unit volume, it cannot be effectively used. Accordingly, there are only two examples of the development of a vertical stripe cylindrical solid electrolyte fuel cell in the world, and the present situation is that practical use has not yet been achieved while having the above-mentioned advantages.

[0008] The present invention aims to provide a vertical-striped cylindrical solid electrolyte fuel cell which solves manufacturing problems and is superior in performance to conventional ones, and promotes early practical use as a power supply source. Aim. More specifically, the present invention provides:
Improvement of output density per unit area (kW / m ² ) and unit volume (kW / m ³ ), prevention of battery destruction when thermal stress occurs, and simplification of battery quality control and manufacturing method It is an object of the present invention to provide a vertical stripe cylindrical solid electrolyte fuel cell.

[0009]

In order to achieve the above object, a vertically striped cylindrical solid electrolyte fuel cell according to the present invention comprises a fuel electrode provided outside a cylindrical porous support tube having one end closed and the other end opened. And a unit cell in which at least one unit cell in which a fuel electrode and the like are stacked outside a cylindrical porous support tube having both ends opened is connected in the longitudinal direction to form a single unit cell assembly. The oxidizing gas supply pipe inserted inside the unit cell assembly allows the oxidizing gas to flow from near the closed end of the unit cell toward the open end, while the unit cell is closed. from the end side around the unit cells so as to flow the fuel gas along the unit cells, yet do
Each cell constituting the single cell assembly is
With a different pond area and a simple separation from the fuel gas supply port
The battery area is set to be larger for the battery.

[0010]

Further, in the vertical stripe cylindrical solid electrolyte fuel cell according to the present invention, an oxidizing gas supply pipe is provided inside the unit cell assembly and a fuel gas supply pipe is provided outside.
A plurality of gas supply ports are provided in each supply pipe according to the length of each corresponding single cell, so that the oxidizing gas and the fuel gas are distributed and supplied in the longitudinal direction of the single cell assembly.

[0012]

Accordingly, a unit cell having a practically usable length can be obtained by manufacturing a unit cell having a length that can be manufactured without any problem using the current manufacturing technology and connecting the unit cell in the vertical direction. In addition, in the case of this fuel cell, the current density decreases as the unit cell on the downstream side where the fuel gas and the oxidizing gas are diluted, that is, farther away from the fuel gas supply port, but the output current increases because the power generation area increases It is uniform and reduces energy loss due to battery overvoltage.

Further, when the oxidizing gas and the fuel gas are supplied separately in the length direction of the cell assembly, the overvoltage loss of the electrode due to the increased diffusion resistance of the diluted oxygen and the fuel gas is reduced, and the energy is effectively used. Use and improve the power generation performance per cell assembly (particularly on the downstream side (portion where the supply gas concentration is low)).

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be described below in detail with reference to the embodiments shown in the drawings.

1 to 5 show an embodiment of the present invention. The problem in the fabrication of this fuel cell is about 50 c
If the length is relatively short, it can be manufactured by the current technology, but it is difficult to manufacture a longer one. In view of this, the present invention makes it possible to extend or shorten the length of one battery by connecting these cells in the length direction while utilizing the current technology. That is, as shown in FIG. 1, a cylindrical cell having one end closed but the other end opened is used for the cell 2 located at the lowermost part. Each of the upper cells 3a,..., 3n constitutes one cell assembly 1 by connecting one or more cylindrical cells having the same diameter and open at both ends. Each cell 2, 3
The connection surfaces of a,..., 3n are subjected to flattening processing, and the direction of the interconnectors 14, 14 is set to the same direction at the time of connection. The electrical connection is made by using nickel felt as before. Furthermore, the length of the cylindrical battery 2 near the fuel supply port 27 (portion where the supply gas concentration is high) is shortened, and the length of the cylindrical batteries 3a,..., 3n away from the fuel supply port 27 (portion where the supply gas concentration is low) is adjusted. Thus, by adjusting the power generation area, it is possible to further reduce the overvoltage of the electrode portion caused by the lean supply gas.

In this single cell, reference numeral 13 denotes a solid electrolyte portion thereof, which is made of, for example, yttria-stabilized zirconia or yttria partially-stabilized zirconia using an electrochemical deposition method. Reference numeral 12 denotes an air electrode, which is made of, for example, lanthanum manganite or lanthanum cobaltite to which strontium or calcium is added by using a slurry dipping method. 15 is a fuel electrode,
For example, it is made of nickel zirconia cermet. An interconnector 14 is made of, for example, lanthanum chromite to which magnesium, strontium, or the like is added. These battery constituent materials are laminated on a porous support tube 11 made of, for example, zirconia stabilized with calcium as shown in FIG.

In addition, these cells 2, 3a, 3b,
, 3n, oxidant gas supply pipes 6 each having a required number of gas supply ports 6a opened according to the length (battery area) of each unit cell are inserted. However, the gas supply pipe 6 is desirably made of ceramics having excellent heat resistance, such as alumina. Also, the cell assembly 1
Are provided with four fuel gas supply pipes 5 each having a required number of fuel gas supply ports 5a in accordance with the length (cell area) of each cell 2, 3a, 3b,..., 3n. The oxidizing gas supply pipe 6 is inserted in the gap of the assembly 1 in the opposite direction. Further, connecting parts 4 for connecting them between the unit cells 2 and the unit cells 3a and between the other unit cells 3a, 3b,..., 3n are mounted. This connection part 4
As shown in FIG. 4, for example, a short cylindrical shape is formed, and grooves 16 for fitting the cells 2 or 3a, 3b ,... , 3n are formed on both end surfaces thereof. 2
Or, 3a, 3b,..., 3n are provided so as to be fitted. The connecting part 4 includes the air electrode 12 and the fuel electrode 1
5 is made of an electrically insulating material so as not to be short-circuited.

The unit cell assembly 1 configured as described above forms a stack by collecting a predetermined number of the unit cells. The stack is housed in the fuel cell casing 10 and is connected to the oxidizing gas supply pipe 6 and the fuel gas supply pipe 5. They are arranged to form a module. Then, the adjacent cell assemblies 1 are electrically connected to each other by the nickel felt 17, and electricity is output through the air electrode current collector 18 and the fuel electrode current collector 19. Here, the fuel cell casing 10 has four chambers of a fuel gas introduction chamber 20, a reaction chamber 21, an oxidizing gas heating chamber 22, and an oxidizing gas supply chamber 23 by the floor plate 7, the partition plate 8, and the ceiling wall plate 9. Is divided into Holes 27 for supplying the fuel gas are formed in the floor plate 7, and projections 28 for fitting the fuel gas supply pipe 5 are fitted to the edges thereof.
Is provided. An unreacted gas (fuel gas) which is not consumed in the reaction chamber 21 and penetrates the partition plate 8 through the end of the porous support tube 11 of the unit cell assembly 1.
Holes 29 for introducing the gas into the oxidizing gas heating chamber 22
Is provided. Further, the ceiling wall plate 9 is provided with a hole 30 through which the oxidizing gas supply pipe 6 is penetrated, and the oxidizing gas in the oxidizing gas supply chamber 23 is supplied to each unit cell assembly through the oxidizing gas supply pipe 6. 1 is provided.

The fuel cell constructed as described above is assembled as follows. First, the fuel gas supply pipe 5 is fitted into the projection 28 of the floor plate 7, and the side walls and the current collecting plates 18, 19 are assembled to produce a box-shaped casing without a lid. Subsequently, after the cell 2 whose one end is closed is placed in a predetermined position, the nickel felt 17 is packed between the cells 2, 2,. Thereafter, the battery connecting parts 4, 4,..., 4 are attached to the respective cells 2,. At this time, a sealing material (not shown) is filled into the groove 16 of each of the battery connecting parts 4,.
It is provided so as not to pass through the gap between the battery and the unit cell 2. Further, the cells 3a, 3a,..., 3a having openings at both ends are inserted into the grooves 16 of the battery connecting parts 4 from above, and nickel felt 17 is packed between the cells 3a, 3a,. If necessary, this assembly may be repeated to increase the length per cell assembly 1. Finally, after setting the partition plate 8 and the ceiling wall plate 9, the oxidizing gas supply pipe 6 is inserted into the unit cell assembly 1 to form the fuel cell casing 10.

In this fuel cell, the fuel gas sent to the lower fuel gas introduction chamber 20, for example, hydrogen heated to a certain extent, passes through the fuel gas supply pipe 5 protruding above the floor plate 7, and the fuel cell of each unit cell assembly 1 Sent around.
On the other hand, the oxidizing gas, for example, air, enters the uppermost oxidizing gas supply chamber 23, receives heat from the oxidizing gas heating chamber 22, is heated, and then passes through the oxidizing gas supply pipe 6 to each of them. It is sent into the cell assembly 1. Electric power is generated by the supplied fuel gas and oxidant gas. The heating of the oxidizing gas (air) is performed in the reaction chamber 21.
The fuel gas and the oxidant gas that have flowed into the oxidant gas heating chamber 22 through the communication hole 29 from the fuel gas are burned by the unused heat.

The above embodiment is a preferred embodiment of the present invention, but the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in this embodiment, the case where the vertically assembled cells are connected in parallel in the horizontal direction is mainly described. However, the present invention is not particularly limited to this, and the cells are electrically connected in the vertical direction ( Series connection) is also possible,
In this case, a large current can be taken out. That is, the cells 2, 3a, 3b,..., 3n that are insulated by the battery connecting parts 4, 4,..., 4 are connected by nickel felt, and the cell assembly 1 is electrically connected to a single battery. I do. Further, in this embodiment, the supply of the oxidizing gas and the fuel gas is distributed from several places using the pipes 5 and 6 having a large number of gas supply ports 5a and 6a, but the present invention is not particularly limited to this. When the cell area of the unit cell is increased as the distance from the fuel gas supply port 27 increases, it is also possible to supply the battery from a single location. In this case, the current density becomes smaller as the unit cell is farther from the fuel gas supply port 27, but the output current itself does not decrease due to the increase in the power generation area, so that an overvoltage does not occur. Further, in the case where the gas concentration is made uniform by increasing the gas supply ports 6a and 5a of the oxidizing gas supply pipe 6 and the fuel gas supply pipe 5 as the gas concentration becomes thinner, the unit cell assembly 1 is constituted. The length of each cell may be the same.

[0022]

As is apparent from the above description, in the present invention, one or more unit cells with both ends open are connected to a unit cell with one end closed to form one unit cell assembly. Therefore, it is possible to increase the capacity of the battery while using the conventional manufacturing technology as it is. In other words, a large-capacity fuel cell can be manufactured by using the conventional manufacturing technology, and it is not necessary to newly develop the manufacturing. The required length can be set according to the conditions to be set, that is, the place, the required capacity, the site area, and the like, and the degree of freedom regarding the size is widened from small to large. The introduction of the conventional technology of manufacturing a product having a size of about 50 cm facilitates quality control and other manufacturing and transportation. Furthermore, if the connection by nickel felt is changed, even one battery in the length direction can be electrically combined as a plurality of batteries, and a high voltage can be obtained. If the unit cell is divided as described above, it becomes necessary to keep the current value of each part where the divided cells are connected in series constant. Can be set, so that the energy loss due to polarization of the cylindrical battery on the upper side (portion where the supply gas concentration is low) can be minimized. From the above, there is a great advantage in terms of cost, and it can be expected that practical application can be promoted.

Further, in the present invention, when the gas supply pipe is also improved in consideration of the length of the battery, it is possible to improve the power generation performance of the battery. Solid electrolyte fuel cells can be provided,
It can be expected to contribute to the improvement of performance as a power supply source and accelerate the promotion of its spread.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an example of a vertical stripe cylindrical solid electrolyte fuel cell of the present invention.

FIG. 2 is a diagram illustrating the structure of a fuel cell according to the present invention.
(A) is a perspective view of a unit cell assembly, and (B) is a perspective view showing a fuel cell module in partial cross section.

FIG. 3 is an exploded perspective view of the fuel cell of the present invention.

FIGS. 4A and 4B are explanatory views of a unit cell connection component, in which FIG. 4A is a longitudinal sectional view and FIG.

FIG. 5 is a perspective view showing the structure of a unit cell of a vertical stripe cylindrical solid electrolyte fuel cell.

FIG. 6 is a perspective view showing a unit cell of a conventional vertical stripe cylindrical solid electrolyte fuel cell.

FIG. 7 is a diagram illustrating a conventional fuel cell stack.
(A) is a perspective view, (B) is a cross-sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single-cell assembly 2 Closed single cell 3 Single-ended cell 4 Connection parts 5 Fuel gas supply pipe 5a Fuel gas supply port 6 Oxidant gas supply pipe 6a Oxidant gas supply port

Continuation of the front page (56) References JP-A-3-59955 (JP, A) JP-A-3-59956 (JP, A) JP-A-63-110560 (JP, A) JP-A-3-280359 (JP) JP-A-5-190195 (JP, A) JP-A-2-75167 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 8/00-8/24

Claims (2)

(57) [Claims] A unit cell in which a fuel electrode and the like are stacked outside a cylindrical porous support tube having one end closed and the other end opened;
At least one unit cell in which a fuel electrode or the like is laminated outside the cylindrical porous support tube having both ends opened is connected in the longitudinal direction to form one unit cell assembly, and the unit cell assembly is provided. The oxidizing gas supply pipe inserted inside the cell allows the oxidizing gas to flow from the vicinity of the closed end of the unit cell toward the open end, and the unit cell from the closed end side of the unit cell. The fuel cell is caused to flow along the cell around the cell, and the cell assembly is constructed.
Each unit cell has a different cell area and the fuel
Cells farther from the gas supply port have larger battery area
A vertically-striped cylindrical solid electrolyte fuel cell characterized by being formed . 2. An oxidizing gas supply pipe is installed inside the unit cell assembly and a fuel gas supply pipe is installed outside, and gas is supplied to each supply pipe according to the length of the corresponding unit cell. providing a plurality of mouth claim 1 Symbol placement vertical stripe cylindrical solid electrolyte fuel cell and supplying to distribute the oxidant gas and the fuel gas in the longitudinal direction of the cell assembly.