JPH0594830A - Vertical stripe cylindrical solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To improve the output density per unit area and per unit volume of a vertical stripe cylindrical solid electrolyte fuel cell, to prevent a battery breakdown to generate a thermal stress, and to make the quality control and the manufacturing of the battery easier. CONSTITUTION:One single cell assembly 1 is to be composed by connecting a single cell 2 whose one end is closed and at least more than one of cylindrical single cells 3a, 3b,..., 3n whose both ends are opened, which have the size manufactured by utilizing the conventional manufacturing technology already established as it is. And the single cells 2, 3a, 3b,..., 3n to compose this single cell assembly 1 are preferably to have different cell areas each other and the cell areas are formed larger as separated farther from a fuel gas feeding port 27. Furthermore, at an oxidizer gas feeding pipe 6 and a fuel gas feeding pipe 5 provided at the inside and the outside of the single cell assembly 1, plural gas feeding holes 5a and 6a are provided to the feeding pipes 5 and 6 according to the lengths of the corresponding single cells 2, 3a, 3b,..., 3n, so as to feed the oxidizer gas and the fuel gas by distributing in the longitudinal direction of the single cell assembly 1.

Description

Detailed Description of the Invention

[0001]

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 installed outside a cylindrical porous support tube, a solid electrolyte, an interconnector, and a fuel electrode are further laminated thereon, and an oxidizer is provided inside the porous support tube. The present invention relates to a vertically striped cylindrical solid electrolyte fuel cell in which a gas flows and a fuel gas flows around a fuel electrode to generate electric power.

[0002]

2. Description of the Related Art Solid electrolyte fuel cells have high power generation efficiency of the cells themselves, and when combined with a bottoming cycle as a large-scale power plant, it can be expected that a high-efficiency power generation system superior to conventional power plants can be constructed. , Its practical application is urgent. Further, since the generation of air pollutant gas is small and the system is expected to be downsized, it can be used as a distributed power source that can avoid energy loss due to long-distance power transmission adjacent to the power consumption area. Further, this solid electrolyte fuel cell is excellent in that, since it is adjacent to the power consumption area, the heat obtained from the fuel cell can be effectively used for cooling and heating, and the energy efficiency can be further improved.

By the way, in the case of a vertically striped cylindrical solid electrolyte fuel cell, for example, a cylindrical fuel cell module having a structure shown in perspective views in FIGS. 6 and 7 has been conventionally proposed. As shown in FIG. 5, this unit cell 101 includes a porous porous electrode 11, 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. The porous support tube 11, as shown in FIGS. 6 and 7,
An oxidant gas supply pipe 107 is inserted from the rear end so that the front end is closed and the rear end is opened, and an oxidant gas such as air is supplied to the vicinity of the front end of the closed porous support pipe. There is. In addition, the unit cells 101, 101,
, 101 is supplied with a fuel gas such as hydrogen from the fuel gas supply port 105 near the closed end of the unit cell 101 and flows along the unit cell 101. The unreacted portion of each gas burns in the space 106 provided above the unit cell 101 and is used for preheating the oxidant gas. In the fuel cell having such a structure, it is not necessary to consider a gas seal for preventing the mixing of the fuel gas and the oxidant gas.

Further, as shown in FIG. 7, the battery 101 is constructed as a stack (assembled battery) by bundling several batteries and electrically connecting them in series and in parallel. At this time, nickel felts 104, 104, ..., 104 are used to connect the respective cells 101, 101, ..., 101, and the generated electricity is generated by these nickel felts 104 ,.
It is taken out from the positive (+) side current collecting plate 102 and the negative (−) side current collecting plate 103 provided above and below the container via 04.

This vertical striped cylindrical solid electrolyte fuel cell is composed only of solid cell constituent materials. The air electrode and the fuel electrode are mainly produced by the slurry dipping method, and the electrolyte and the interconnector are produced by the electrochemical vapor deposition method. ing. Also,
Porous support tube 11 as is apparent from FIGS. 6 and 7.
Since it has a cylindrical structure with a battery formed on it, it has a large mechanical strength, and even if the electrolyte membrane has a thickness of 20 to 50 μm, it can be increased in current density per unit area without being destroyed by thermal shock or the like. There is an advantage that the output can be improved.

[0006]

However, the vertical stripe cylinder type solid electrolyte fuel cell also has a weak point. That is, first, there is a manufacturing problem. First, in the slurry dipping method, the porous support tube 11 is immersed in a slurry (mud-like ceramics) of an air electrode material or a fuel electrode material. Since the ceramics drips downward, it is difficult to form a uniform film thickness. In addition, the corrosion resistance of the device is also a problem in the production of electrolytes and interconnectors by the electrochemical deposition method using metal chloride at high temperature, but it is extremely difficult to control the film thickness especially when the area of the film-formed portion is large. As a result, the current manufacturing technology can only manufacture a film having a length of about 50 cm. This is because in the conventional film forming method, the reaction is likely to occur in the vicinity of the supply of the raw material, and the concentration of the raw material gas becomes diluted and the reaction is hard to occur in the location far from the supply port. The film thickness also varies depending on the situation. From the above two points, it is difficult to make the length of one battery to a practical level of 1 to 2 m, and it is a big obstacle to practical use of the solid electrolyte fuel cell under the present circumstances. ..

Even if the length of the cylindrical solid oxide fuel cell can be increased, the conventional method for supplying the oxidant gas and the fuel gas causes the supplied gas to flow as it flows to the end of the cell. The concentration of is diminished, and in large-capacity batteries, there is a difference in the current value that can be taken out in the length direction on the battery surface, resulting in a large electrode overvoltage (voltage drop other than the battery resistance of the material) and effective use of energy. However, the effective use of the electrode area cannot be achieved. That is, in order to increase the output density per unit volume, no matter how long the unit cell is, it cannot be effectively used. Therefore, there are only two examples of the development of the vertical stripe cylindrical solid oxide fuel cell in the world, and it is the current situation that the vertical stripe cylindrical solid oxide fuel cell has not been put into practical use while having the above-mentioned advantages.

The present invention provides a vertical striped cylindrical solid electrolyte fuel cell which solves the problems in production and is superior in performance to conventional ones, and promotes early commercialization as a power supply source. To aim. More specifically, the present invention is
It is possible to improve the power density per unit area (kW / m ² ) and per unit volume (kW / m ³ ), prevent battery destruction when thermal stress occurs, and facilitate battery quality control and manufacturing methods. An object of the present invention is to provide a vertical striped cylindrical solid oxide fuel cell.

[0009]

In order to achieve the above object, the vertical striped cylindrical solid electrolyte fuel cell of the present invention comprises a fuel electrode on the outside of a cylindrical porous support tube having one end closed and the other end open. And the like, and a unitary cell assembly in which at least one or more unitary cells in which a fuel electrode or the like is laminated outside the cylindrical porous support tube with both ends opened are vertically connected to form a unitary cell assembly. The oxidant gas is supplied from the vicinity of the closed end of the unit cell toward the open end by the oxidant gas supply pipe inserted inside the unit cell assembly, while the unit cell is closed. The fuel gas is made to flow from the end side to the periphery of the unit cell along the unit cell.

Further, in the vertical-striped cylindrical solid oxide fuel cell of the present invention, each cell constituting the cell assembly has a different cell area, and the cell area becomes larger as the cell is farther from the fuel gas supply port. I am trying.

In the vertical striped cylindrical solid oxide fuel cell of the present invention, the oxidant gas supply pipe is installed inside the unit cell assembly and the fuel gas supply pipe is installed outside the unit assembly.
A plurality of gas supply ports are provided in each supply pipe according to the length of each corresponding single cell, and the oxidant gas and the fuel gas are distributed and supplied in the longitudinal direction of the single cell assembly.

[0012]

Therefore, a unit cell assembly having a length of a practical level can be obtained by manufacturing unit cells of a length that can be manufactured without problems by the current manufacturing technique and connecting them in the vertical direction. Moreover, in the case of this fuel cell, the current density becomes smaller in the unit cell on the downstream side where the fuel gas and the oxidant gas are diluted, that is, farther from the fuel gas supply port, but the power generation area becomes larger, so the output current is almost the same. It is homogenized and reduces energy loss due to battery overvoltage.

When the oxidant gas and the fuel gas are separately supplied in the length direction of the unit cell assembly, the overvoltage loss of the electrode due to the increase in the diffusion resistance of the dilute oxygen and the fuel gas is reduced and the energy is effectively used. Use and improve the power generation performance per cell assembly (especially on the downstream side (where the supply gas concentration is low)).

[0014]

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

1 to 5 show an embodiment of the present invention. As described above, the problem in manufacturing this fuel cell is about 50c.
If the length is relatively short, such as m or less, it can be manufactured by the current technology, but if it is longer than that, it is difficult to manufacture. Therefore, in the present invention, while utilizing the current technology, the length of each battery can be lengthened or shortened by connecting these unit cells in the length direction. That is, as shown in FIG. 1, a cylindrical cell having one end closed and the other end open is used for the cell 2 located at the bottom. , 3n are connected to one or more cylindrical cells of the same diameter with both ends opened to form one cell assembly 1. Each cell 2, 3
The connection surfaces of a, ..., 3n are subjected to flattening processing so that the directions of the interconnectors 14, 14 are the same when connecting. The electrical connection is made by using nickel felt as before. Further, the cylindrical battery 2 near the fuel supply port 27 (the part where the supply gas concentration is high) is shortened, and the cylindrical batteries 3a, ..., 3n apart from the fuel supply port 27 (the part where the supply gas concentration is low) are adjusted long. Therefore, by adjusting the power generation area, it is possible to further reduce the overvoltage of the electrode portion caused by the supply gas being diluted.

In this unit cell, 13 is a solid electrolyte portion thereof, and for example, yttria-stabilized zirconia, yttria partially-stabilized zirconia, etc. are produced by an electrochemical vapor 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 made by nickel zirconia cermet. Further, 14 is an interconnector, which is made of, for example, lanthanum chromite to which magnesium, strontium or the like is added. As shown in FIG. 5, these battery constituent materials are laminated on a porous support tube 11 made of, for example, calcium-stabilized zirconia.

Further, these unit cells 2, 3a, 3b,
, 3n are provided with 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. However, it is desired that the gas supply pipe 6 is made of ceramics having excellent heat resistance such as alumina. Also, single cell assembly 1
Around the cell, there are four fuel gas supply pipes 5 each having four fuel gas supply ports 5a opened according to the length (cell area) of each cell 2, 3a, 3b, ..., 3n. It is inserted in the gap of the assembly 1 in the direction opposite to the oxidant gas supply pipe 6. Further, a connection component 4 for connecting them is mounted between the unit cell 2 and the unit cell 3a and between the other unit cells 3a, 3b, ..., 3n. This connection part 4
For example, as shown in FIG. 4, a short cylindrical shape is formed, and a groove 16 for fitting the unit cells 2 or 3a, 3b, ..., 3n is formed on both end faces thereof. Two
Alternatively, 3a, 3b, ..., 3n are provided so as to be fitted therein. This connecting part 4 is composed of an air electrode 12 and a fuel electrode 1.
It is made of an electrically insulating material so as not to short circuit.

A predetermined number of unit cell assemblies 1 having the above-described structure are assembled to form a stack, which is housed in a fuel cell casing 10 to form an oxidant gas supply pipe 6 and a fuel gas supply pipe 5. Arranged to form a module. Then, the adjacent unit cell assemblies 1 are electrically connected to each other by the nickel felt 17, and electricity is output via the air electrode current collector plate 18 and the fuel electrode current collector plate 19. Here, the fuel cell casing 10 is composed of a floor plate 7, a partition plate 8 and a ceiling wall plate 9, and is composed of four chambers including a fuel gas introduction chamber 20, a reaction chamber 21, an oxidant gas heating chamber 22 and an oxidant gas supply chamber 23. It is divided into The floor plate 7 is provided with holes 27 for supplying the fuel gas, and the edges thereof have projections 28 for fitting the fuel gas supply pipe 5 therein.
Is provided. The partition plate 8 penetrates the end of the porous support tube 11 of the unit cell assembly 1 and does not consume the unreacted gas (fuel gas) in the reaction chamber 21.
Communicating hole 29 for introducing oxygen into the oxidizing gas heating chamber 22
Is provided. Further, the ceiling wall plate 9 is provided with a hole 30 for penetrating the oxidant gas supply pipe 6, and the oxidant gas in the oxidant gas supply chamber 23 is passed through the oxidant gas supply pipe 6 to each unit cell assembly. It is provided so that it may be supplied to the inside.

The fuel cell constructed as above is assembled as follows. First, the fuel gas supply pipe 5 is fitted into the protrusion 28 of the floor plate 7, and the side walls and the current collecting plates 18 and 19 are assembled to form a box-like casing without a lid. Subsequently, the unit cell 2 with one end closed is placed at a predetermined position, and then the nickel felt 17 is packed between the unit cells 2, 2 ,. After that, the battery connecting parts 4, 4, ..., 4 are attached to each of the cells 2 ,. At this time, the groove 16 of each of the battery connecting parts 4, ..., 4 is filled with a sealing material (not shown) so that the oxidizing gas or the fuel gas is filled with the battery connecting parts 4.
It is provided so as not to pass through the gap between the unit cell 2 and the unit cell 2. Further, the cells 3a, 3a, ..., 3a having openings at both ends are inserted from above into the groove 16 of the cell connecting component 4, and the nickel felt 17 is packed between the cells 3a, 3a ,. If necessary, this assembly may be repeated to increase the length of each single battery assembly 1. Finally, the partition plate 8 and the ceiling wall plate 9 are set, and then the oxidant 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 introducing chamber 20, for example, hydrogen which has been heated to some extent, passes through the fuel gas supply pipe 5 projecting on the floor plate 7 of each unit cell assembly 1. It is sent to the surroundings.
On the other hand, the oxidant gas, for example, air, enters the oxidant gas supply chamber 23 at the top and is heated by receiving heat from the oxidant gas heating chamber 22, and thereafter passes through the oxidant gas supply pipe 6 to reach each It is fed into the unit 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.
This is performed by the heat generated when the unused portion of the fuel gas and the oxidant gas, which has flowed into the oxidant gas heating chamber 22 through the communication hole 29, burns.

It should be noted that the above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, although the present embodiment has mainly described the case where the vertically assembled cells are connected in parallel in the horizontal direction, the present invention is not particularly limited to this, and the cells are electrically connected in the vertical direction ( It is also possible to connect in series,
In this case, a large current can be taken out. That is, the individual cells 2, 3a, 3b, ..., 3n that are insulated by the battery connecting parts 4, 4, ..., 4 are connected by nickel felt, and the single cell assembly 1 is made into an electrically single battery. To do. Further, in the present embodiment, the supply of the oxidant gas and the fuel gas is distributed from several places by utilizing the pipes 5 and 6 having the numerous gas supply ports 5a and 6a, but the present invention is not particularly limited to this. In the case where the cell area of the unit cell is increased as the distance from the fuel gas supply port 27 increases, it is possible to supply from a single location. In this case, the electric 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 the overvoltage does not occur. Further, when the gas supply ports 6a, 5a of the oxidant gas supply pipe 6 and the fuel gas supply pipe 5 are increased toward the upper side where the gas concentration becomes thin to make the gas concentration uniform, the unit cell assembly 1 is configured. The length of each cell may be the same.

[0022]

As is apparent from the above description, according to the present invention, one cell having one end closed is connected to one or more cells having openings at both ends to form one cell assembly. The large capacity of the battery is possible while using the conventional manufacturing technology as it is. That is, it becomes possible to manufacture a large-capacity fuel cell by using the conventional manufacturing technique, and it is not necessary to newly develop the manufacturing. The required length can be set depending on the conditions to be set, that is, the place, the required capacity, the site area, etc., and the degree of freedom regarding the size increases from the small to the large. By introducing the conventional technique of manufacturing a product of about 50 cm, quality control and other manufacturing and transportation are easy. Furthermore, if the connection by nickel felt is changed, even one battery in the length direction can be electrically combined into a plurality of batteries, and a high voltage can be obtained. If the unit cell is divided as described above, the current value of each part where the divided cells are connected in series needs to be constant, so the optimum area is adjusted according to the expected concentration of the supply gas. Can also be set, so that the energy loss due to polarization of the cylindrical battery on the upper side (the 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 the 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 and to solve the conventional problems such as the vertical stripe cylindrical type. Solid electrolyte fuel cell can be provided,
It can be expected to contribute to the improvement of performance as a power supply source and accelerate its promotion.

[Brief description of drawings]

FIG. 1 is a vertical cross-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 the fuel cell of the present invention,
(A) is a perspective view of a unit cell assembly, and (B) is a perspective view showing a partial cross section of a fuel cell module.

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

FIG. 4 is an explanatory view of a unit cell connecting component, (A) is a longitudinal sectional view and (B) is a plan view.

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single cell assembly 2 Closed single cell 3 Both ends open single cell 4 Connection parts 5 Fuel gas supply pipe 5a Fuel gas supply port 6 Oxidizing gas supply pipe 6a Oxidizing gas supply port

Claims (3)

[Claims] 1. A unit cell in which a fuel electrode or the like is laminated outside a cylindrical porous support tube having one end closed and the other end open,
At least one unit cell in which a fuel electrode or the like is laminated is connected to the outside of a cylindrical porous support tube having both ends opened in the longitudinal direction to form one unit cell assembly, and the unit cell assembly is provided. While flowing the oxidant gas from the vicinity of the closed end of the unit cell toward the open end by the oxidant gas supply pipe inserted inside the unit cell, A vertically striped cylindrical solid electrolyte fuel cell, characterized in that a fuel gas is caused to flow around the periphery of the unit cell. 2. The unit cells constituting the unit cell assembly have different cell areas, and the unit cells are formed to have a larger cell area as they are farther from the fuel gas supply port. Vertical striped cylindrical solid oxide fuel cell. 3. An oxidant gas supply pipe is installed inside the unit cell assembly and a fuel gas supply pipe is installed outside the unit cell assembly, and gas is supplied to each supply pipe according to the length of each corresponding unit cell. The vertical striped cylindrical solid electrolyte fuel cell according to claim 1 or 2, wherein a plurality of ports are provided so that the oxidant gas and the fuel gas are distributed in the longitudinal direction of the unit cell assembly and supplied.