JPH08203552A - Solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE: To provide a solid electrolyte fuel cell which improves uniformity of electrochemical combustion reaction in a power generation chamber integrating cylindrical cells and improve reactivity of gas flowing in a gas flow path in the outside of cells. CONSTITUTION: This solid electrolyte fuel cell is a so-called cylindrical cell type solid electrolyte fuel cell. A gas introduction tube 9a is provided in a space between cells partitioned by outer circumferencial faces of adjoining cylindrical cells 9 and it is so constituted that gas is supplied from this gas introduction pipe 9a to the outer faces of the cylindrical cells 6. And air or fuel in its unexhausted state is directly supplied from the gas introduction pipe 9a to the whole area of the outside of the cylindrical cells 6.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cylindrical cell type solid oxide fuel cell (hereinafter also referred to as CTC-SOFC).
Regarding In particular, while enhancing the uniformity of the electrochemical combustion reaction in the power generation chamber where the cylindrical cells are integrated,
The present invention relates to a solid oxide fuel cell in which the reaction rate of gas flowing in a gas (air, fuel) flow path outside a cell is increased and power generation performance is improved.

[0002]

2. Description of the Related Art FIG. 3 is a side sectional view showing a main part of a CTC-SOFC disclosed in Japanese Patent Laid-Open No. 4-294068. FIG. 4 is a cross-sectional view of the CTC-SOFC cylindrical cell group of FIG. 3 taken along a cross section perpendicular to the axial direction. In addition, adjacent 4
Only the cylindrical cell of the book is shown. This CTC-
A feature of SOFC is that the fuel gas supply port for feeding fuel to the cell is provided not only in the partition 3 at the bottom of the cell but also in the partition 4 at the side of the cell. This makes the fuel concentration around the cell more uniform and eliminates the unevenness of the electrochemical combustion reaction. As a result, the temperature difference in the longitudinal direction of the cell is reduced to prevent damage to the device and improve power generation efficiency. It is said that you can do it.

The SOFC shown in FIGS. 3 and 4 will be specifically described. In this SOFC, cylindrical cells 6 having a bottomed cylindrical shape are connected in series and in parallel to form an assembled battery. Like the known cells, each cell 6 is laminated in a multi-layered hollow cylindrical shape (FIG. 4), and is laminated with a porous support 17, an air electrode 18, and a solid electrolyte 19 from the inside, and further with a fuel on the outermost side. The electrode 20 is laminated. Further, in the upper region of the cell 6, the interconnector 16 is provided on the air electrode 18, and the connection terminal 13 is laminated thereon. The interconnector 16 connects the cylindrical cells 6 in series (upper and lower in the figure), and includes the air electrode 18 of the cylindrical cell 6 and the outermost layer of the cylindrical cell 6 adjacent to the cell 6. The fuel electrode 20 of the connection terminal 1
3. Connect via metal felt 14. The cylindrical cells 6 are also connected in parallel (left and right in the figure). That is, the outermost fuel electrodes 2 of the cylindrical cells 6 adjacent to each other on the left and right sides.
The zeros are connected via the metal felt 14.

With the thus constructed cell assembly heated to the operating temperature (about 1000 ° C.), the inner hole 1 of the cell 6
When air (or oxygen) is caused to flow through 5 and a fuel such as H ₂ · CO is caused to flow over the outer surface (outside of the fuel electrode 20), O ²⁻ ions move inside the cell to cause electrochemical combustion and the air electrode A positive voltage is generated at 18 and a negative voltage is generated at the fuel electrode 20. Since the interconnector 16 is electrically connected to the air electrode 18, the interconnector 16 also becomes positive. The generated voltage of each cell is about 1 volt, so
To get an output voltage of 00 volts, 100 cells must be connected in series.

A current collector plate 5 is in contact with the outermost row (left and right in FIG. 3) of the cell assembly. One current collector plate 5 is electrically connected to the interconnector 16 of the cell 6. The other current collector plate 5 is electrically connected to the outer surface electrode 20 of the cell 6. Therefore, the positive output voltage of the entire cell is output to one current collector plate, and the negative output voltage of the entire cell is output to the other current collector plate.

A substantially rectangular parallelepiped casing 1 made of a heat insulating material is formed so as to surround the side partition wall 4, and a fuel chamber 2 is provided between the casing 1 and the lower partition wall 3 and the side partition wall 4. There is. The fuel chamber 2 has a substantially U-shaped cross section in FIG. The upper end of the fuel chamber 2 and the exhaust gas chamber 8 are separated by the casing 1. A fuel supply port 4a is provided at the bottom of the casing 1.

The positive and negative electrodes of the assembled battery constructed by connecting the cylindrical cells 6 in series and in parallel in this way are provided on both sides of the group of cylindrical cells 6 (FIG. 3). Electrically connect to. A pair of the current collector plates 5 act as a current collector of the assembled battery and are connected to lead wires (not shown). The assembled battery and the collector plate 5 are housed in the power generation chamber 12 in an integrated state.

Of the partition walls forming the power generation chamber 12, an upper partition wall 7 is provided on the open end side (upper side in FIG. 3) of the cylindrical cell 6 having a bottomed cylindrical shape. An exhaust gas port 7a is opened in the upper partition wall 7 corresponding to the position of the cell 6, and the open end of the cell 6 is inserted into the exhaust gas port. An air introduction pipe 10 is inserted into each cell inner hole 15 of each cell 6. The air introduction pipe 10 extends downward in the inner hole 15 of the cell 6, the tip thereof reaches near the bottom of the cell inner hole 15, and air is blown into the cell from the tip. This air (oxidant) flows upward in the drawing inside the cell inner hole 15, finally exits upward from the cell 6, and flows into the exhaust gas chamber 8 as indicated by arrow D.

The lower partition wall 3 has a plurality of fuel supply ports 3a.
Are provided at a predetermined distance from each other. Further, each side partition wall 4 is provided with a fuel supply port 4a. Further, each current collector plate 5 also has a through hole 5a formed at a position corresponding to the fuel supply port 4a of the side partition wall.

When operating this power generator, fuel is supplied from the fuel supply port 1a to the fuel chamber 2 as shown by arrow A. As a result, fuel is supplied from the fuel supply ports 3a into the power generation chamber 12 as indicated by arrow B. At the same time, the fuel is supplied into the power generation chamber 12 through the fuel supply port 4a of each side partition wall 4 and the through hole 5a of each current collector plate 5 as indicated by arrow C. The fuel, which has been sufficiently used for power generation in the cylindrical cells 6 and has been depleted, finally passes through the interval (exhaust gas port 7a) between each cylindrical cell 6 and the upper partition wall 7 and flows into the exhaust gas chamber 8 as indicated by arrow E. Then, it is mixed with oxygen-depleted air blown out from the inside of the cell 6.

[0011]

In the CTC-SOFC of JP-A-4-294068 shown in FIGS. 3 and 4, the fuel is also supplied from the side partition wall 4 of the power generation chamber 12, so the lower partition wall is certainly used. SO fueled from only 3
Compared to FC, the fuel concentration around the cell 6 is uniform. However, there is still a difference in the fuel concentration around the cell between the cell near the side partition wall 4 and the cell located far from the side partition wall 4. This is because while the fuel reaches the center of the power generation chamber 12 from the side partition walls 4, the fuel is consumed by the cells near the side partition walls and combustion exhaust gas (CO ₂ , H ₂ O) is generated. The problem of the decrease in fuel concentration in the central portion of the power generation chamber 12 becomes more serious as the cell integration degree in the power generation chamber 12 increases. In an actual SOFC, unlike the schematic diagram shown in FIG. 3, several tens to several hundreds of cells are integrated in one row.

Further, there is another serious problem in the conventional CTC-SOFC. That is, of the fuel flowing through the gas passage 21 outside the cell, a considerable part of the fuel flowing in the portion far from the surface of the cell (the central portion of the flow passage) does not come into contact with the cell, so that it is necessary for the electrochemical combustion reaction in the cell. Otherwise, there is a possibility that the gas is discharged outside the power generation chamber 12. Incidentally, the cross-sectional area of the gas passage 21 outside the cell was close to 30% of the cross-sectional area of the cell (cell assembly portion).
The unreacted fuel is used for normal combustion outside the power generation chamber, and its sensible heat is effectively used to some extent.
To increase the power generation efficiency of the OFC power generation system as a whole,
It is desirable that more fuel react within the cell to contribute directly to power generation. On the other hand, when air is flown through the gas flow path outside the cell, there is a similar problem from the viewpoint of preventing heat loss caused by flowing extra air.

The present invention enhances the uniformity of the electrochemical combustion reaction in the power generation chamber in which the cylindrical cells are integrated, and also enhances the reactivity of the gas flowing in the gas flow passage outside the cell to improve the power generation performance and durability. It is an object of the present invention to provide a solid oxide fuel cell having improved characteristics.

[0014]

In order to solve the above problems, a solid oxide fuel cell of the present invention comprises an air electrode, a solid electrolyte layer and a fuel electrode laminated in a multi-layer hollow cylindrical shape,
An assembly of a plurality of cylindrical cells having an interconnector that is electrically connected to an inner electrode (inner electrode) of the air electrode or the fuel electrode and that is exposed on the outer surface of the cylinder; The assembly is arranged such that the electrodes on the outer surface of adjacent cylindrical cells (outer surface electrodes) and interconnectors are arranged in contact with each other, and the hollow portion and outer peripheral portion of the cylindrical cells are
Cylindrical cell type solid oxide fuel cells, each of which forms a flow path for air (oxidizer) or gaseous fuel (both are referred to as gas); between cells defined by outer peripheral surfaces of adjacent cylindrical cells. A gas introducing pipe is provided in the space, and the gas is introduced from the gas introducing pipe to the outer surface of the cylindrical cell.

[0015]

In the SOFC of the present invention, since the gas introduction pipe is provided in the space between the cells, the air or fuel is directly worn on the entire outer surface of the cylindrical cell from the gas introduction pipe without being worn. Can be supplied. Therefore, unlike SOFC in which gas is introduced into the power generation chamber only from the fuel supply port of the partition wall as in the past, the concentration of gas (active component) around the cell in the upper part of the power generation chamber can be increased and the longitudinal direction of the cell can be increased. A uniform electrochemical combustion reaction takes place.

Further, the SOF disclosed in JP-A-4-294068
The problem of eliminating the difference in gas concentration between the cells in the vicinity of the partition walls on the side of the power generation chamber and the cells in the center of the power generation chamber, which could not be solved by C, can be solved. It can be said that the SOFC of the present invention has a three-dimensionally uniform gas concentration in the power generation chamber.

Further, since the gas introduction pipe exists in the central portion of the gas passage outside the cell, the gas flow in the same passage passes near the outer surface of the cell. Therefore, most of the gas comes into contact with the outer surface of the cell and participates in the electrochemical combustion reaction in the cell, further improving the power generation performance. If the gas introduction pipe is made of an insulating material, it can be brought into contact with the cell (for example, to support it).

[0018]

Embodiments of the present invention will be described below. Figure 1
A solid oxide fuel cell (SOF) according to an embodiment of the present invention.
It is sectional drawing showing the structure of C). FIG. 2 shows the CTC of FIG.
FIG. 6 is a cross-sectional view of a SOFC cylindrical cell group taken along a cross section perpendicular to the axial direction. Note that only four adjacent cylindrical cells are shown. In addition, S of the conventional example of FIGS.
The same parts as the OFC are indicated by the same reference numerals.

A feature of the SOFC of the present invention in FIG. 1 is that a fuel introduction pipe 9 which is a gas introduction pipe is provided around the cell 6 and substantially parallel to the cell 6. The fuel introduction pipe 9 rises from the lower partition wall 3 of the power generation chamber 12, and the tip thereof reaches just below the upper partition wall 7. The lower end of the fuel introduction pipe 9 is open, and the fuel supply 3 is opened in the lower partition wall 3.
It is connected to the fuel chamber 2 through a, and the fuel is supplied into the fuel introducing pipe 9. On the other hand, the upper end of the fuel introduction pipe 9 is closed.

As shown in FIGS. 1 and 2, the side wall of the fuel introducing pipe 9 is provided with a large number of fuel blowing holes 9a so that the fuel inside the fuel introducing pipe 9 is outside the fuel introducing pipe 9. Then, the fuel is supplied to the outer peripheral surface of the cell 6.

The diameter and pitch (distribution) of the fuel outlet holes 9a of the fuel introducing pipe 9 can be designed arbitrarily. Further, if the fuel introducing pipe 9 is made of a porous material, it is not necessary to newly process the fuel outlet hole 9a. Examples of the material of the fuel introducing pipe 9 include ceramics such as alumina and zirconia, and nickel-based heat resistant alloys. Examples of the method for manufacturing the ceramic fuel introduction pipe 9 include an extrusion method and
A method of grinding after pressure molding can be mentioned.

[0022]

As is apparent from the above description, the solid oxide fuel cell of the present invention exhibits the following effects. Since the fresh fuel gas (or air) can be supplied to the surroundings of each of the power generation cells arranged in the power generation chamber through the gas introduction pipes that are arranged between the power generation cells, all over in an arbitrary distribution amount, power generation is possible. The electrochemical combustion reaction on the cell surface in the room can be three-dimensionally made uniform and optimized. Therefore, the temperature distribution of the cell and the thermal stress caused thereby are relaxed, and the durability of the cell is improved.

For the same reason, it is possible to improve the level of the average electrochemical combustion reaction in each part of a large number of cells. Therefore, the total output of SOFC increases. Since the gas flowing through the gas flow path outside the cell flows close to the cell surface, the reaction rate of the gas increases and the power generation efficiency increases.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a structure of a solid oxide fuel cell device (SOFC) according to an embodiment of the present invention.

2 is a cross-sectional view of the SOFC cylindrical cell group of FIG. 1 taken along a cross section perpendicular to the axial direction.

FIG. 3 CTC-SOF disclosed in Japanese Patent Laid-Open No. 4-294068
It is a side surface sectional view which shows the principal part of C.

4 is a cross-sectional view of the CTC-SOFC cylindrical cell group of FIG. 3 taken along a cross section perpendicular to the axial direction.

[Explanation of symbols]

1 Casing 1a Fuel source pipe 2 Fuel chamber 3 Lower partition wall 3a Fuel supply port 4 Side partition wall 4a Fuel supply port 6 Cylindrical cell 7 Upper partition wall 7a Exhaust gas outlet 8 Exhaust gas chamber 9 Fuel inlet pipe 9a Fuel outlet 10 Air inlet Tube 12 Power Generation Room 13 Connection Terminal 14 Metal Felt 14 'Metal Felt 15 Cell Inner Hole 16 Interconnector 17 Support Tube 18 Air Electrode 19 Solid Electrolyte 20 Fuel Electrode 21 Outer Gas Flow Channel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimoyasu Tachibana 2-47 Shiobara, Minami-ku, Fukuoka City Kyushu Electric Power Co., Inc. Research Institute (72) Masanobu Aizawa 2-chome, Nakajima, Kitakyushu, Kitakyushu, Fukuoka No. 1 Totoki Co., Ltd. (72) Inventor Masahiro Kuroishi 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka Prefecture (72) Totoki Co., Ltd. (72) Haruo Nishiyama, Kokurakita-ku, Kitakyushu, Fukuoka Nakajima 2-1-1 Totoki Kiki Co., Ltd. (72) Inventor Hiroyuki Nagayama 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu, Kitakyushu, Fukuoka Prefecture (72) Inventor Akira Ueno Kitakyushu, Fukuoka 2-1-1, Nakajima, Kokurakita-ku, Tochi, Ltd. (72) Inventor Shigeru Kojima 2-1-1, Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka Prefecture House

Claims (3)

[Claims] 1. An air electrode laminated in a multilayer hollow cylinder shape,
An assembly of a plurality of cylindrical cells having a solid electrolyte layer and a fuel electrode, and an interconnector electrically connected to an inner electrode (inner electrode) of the air electrode or the fuel electrode and exposed on the outer surface of the cylinder. In the cylindrical cell assembly, electrodes (outer surface electrodes) on the outer surfaces of adjacent cylindrical cells and interconnectors are arranged in contact with each other, and the hollow portion and the outer peripheral portion of the cylindrical cells are respectively A solid oxide fuel cell of a cylindrical cell type that forms a flow path of air (oxidizer) or gaseous fuel (both are referred to as gas); between cells defined by outer peripheral surfaces of adjacent cylindrical cells. A solid oxide fuel cell, characterized in that a gas introduction pipe is provided in the space, and gas is supplied from the gas introduction pipe to the outer surface of the cylindrical cell. 2. The solid oxide fuel cell according to claim 1, wherein the gas inlet tube is formed of a porous body. 3. The solid oxide fuel cell according to claim 1, wherein the gas inlet pipe is provided with a gas outlet.