JPH11185775A - Power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lowering of airtightness between electric cells and a gas supply pipe, in the power generation device for a solid electrolyte fuel cell. SOLUTION: This power generation device is provided with at least air electrodes, fuel electrodes and solid electrolytes, also it is provided with an electric cell 1A prepared with a gas passage 5 for letting flow one side gas for power generation, a gas circulating pipe which is a ceramic gas circulating pipe 18 mounted to the electric cell 1A and used for supplying and exhausting gas to a gas passage 5, a power generating chamber 15 for containing the electric cell 1A and flowing the other side gas for power generation, a gas chamber 24 for flowing one side gas for power generation, and a diaphragm 20 separating the one side gas for power generation from the other side gas for power generation. The gas circulating pipe is airtightly joined with the electric cell 1A. The gas circulating pipe penetrates the diaphragm 20. The gas chamber 24, space 18a inside the pipe and the gas passage 5 are communicated each other. The gas circulating pipe is sealed so as to move to the diaphragm 20 with airtightness being kept to the diaphragm 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generator for a solid oxide fuel cell.

[0002]

2. Description of the Related Art Solid oxide fuel cells (SOFCs)
It is roughly classified into a flat plate type and a cylindrical type (Comprehensive Energy Engineering 1)
3-2, 1990). The electromotive force of a SOFC cell is
Approximately 1 V in open circuit, and current density is at most several hundred mA /
Since it is about cm ² , in actual use, it is important that cells having a large power generation area can be easily connected in series and in parallel. From this viewpoint, the structure of the unit cell and its stack (collective cell) must be examined.

[0003] In particular, in a stack structure of a solid oxide fuel cell, it is required to maintain airtightness between the oxidizing gas and the fuel gas at the operating temperature of the power generator. For example,
In a so-called Westinghouse type solid electrolyte fuel cell, a cylindrical air electrode is used as a base, and a solid electrolyte film and a fuel electrode film are formed thereon. The present applicant also discloses a flat unit cell having a structure in which a laminated sintered body including an air electrode and an interconnector is used as an air electrode / interconnector base, and a solid electrolyte film and a fuel electrode film are formed thereon. Disclosed. Then, the end of the oxidizing gas supply pipe is air-tightly joined to the end of the cell, and the oxidizing gas is supplied from the oxidizing gas supply pipe into each gas passage of the cell. The exhaust oxidizing gas discharged from each oxidizing gas passage of the unit cell is guided to flow to the combustion chamber, and is reacted with the exhaust fuel gas in the combustion chamber. (The above is described in JP-A-5
-088990).

[0004]

However, the following problems remain in the above-described unit cell seal structure. That is, when the start-up, operation, and shutdown of the power generation device are actually repeated many times, the airtightness between the unit cell and the oxidizing gas supply pipe is reduced, and the power generation efficiency and electromotive force tend to be reduced. There was something.

An object of the present invention is to separate an oxidizing gas and a fuel gas by joining a unit cell to a gas flow pipe such as an oxidizing gas supply pipe in a power generator so as to maintain airtightness. It is an object of the present invention to prevent a decrease in airtightness between a unit cell and an oxidizing gas supply pipe, and to prevent a decrease in power generation efficiency and electromotive force.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a power generator for a solid oxide fuel cell, wherein the power generator includes at least an air electrode, a fuel electrode, and a solid electrolyte, and one of the power generation gases is used for power generation. A cell of a solid oxide fuel cell provided with a gas passage for flowing, a ceramic gas distribution pipe attached to the cell, for supplying or discharging gas to the gas passage. A gas chamber for accommodating a gas flow tube and a unit cell, and a gas chamber for flowing one power generation gas, a power generation chamber for flowing the other power generation gas, and separating one power generation gas from the other power generation gas The gas flow pipe is hermetically bonded to the unit cell, the gas flow pipe penetrates the partition, and the gas chamber, the inner space of the gas flow pipe, and the gas passage are provided. Communication and the gas distribution pipe Characterized in that it is sealed so as to be movable relative to the septum while maintaining airtightness against the wall.

The present inventors have studied the cause of the decrease in airtightness at the boundary between a unit cell and a gas flow pipe such as an oxidizing gas supply pipe, and have obtained the following findings. The cell and the gas flow pipe are joined to each other by a seal material, and glass or ceramic is used as the seal material. On the other hand, the temperature in the container that accommodates an assembled battery (called a stack) composed of a plurality of unit cells is 1000 when generating power.
° C or higher. Further, the material of the gas flow pipe must be stable to both the oxidizing gas and the fuel gas at the power generation temperature, and is made of, for example, alumina or the like. The gas flow pipe is fixed to the partition.

For example, the space between the gas flow pipe and the cell is sealed with Pyrex glass, but when the operation is stopped and the temperature drops, both the cell and the gas flow pipe shrink, The battery pulls the gas flow tube. It is considered that this tensile stress is applied to the glass seal portion and the airtightness of the seal portion is reduced.

On the other hand, a method of preventing the sealing portion from lowering in airtightness by forming the sealing portion with a material having a higher strength can be considered. In this case, however, an excessive stress is applied to the unit cell. May be added.

On the other hand, the present inventor has proposed that the gas flow pipe be sealed so as to be movable with respect to the partition wall between the power generation chamber and the gas chamber while maintaining airtightness with respect to the partition wall. I thought. Thereby, for example, when the cell and the gas flow tube shrink, and a tensile stress is applied from the cell to the gas flow tube, the gas flow tube is displaced toward the cell and the sealing portion Alleviates the tensile stress applied to

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a sealing device for sealing between a gas flow pipe and a partition is not particularly limited. In a preferred embodiment, the sealing device
An O-ring is provided for contacting the gas flow pipe and the partition, a pressing member for pressing the O-ring toward the partition, and adjusting means for adjusting a pressing force of the O-ring against the partition. The adjusting means is not particularly limited, but a screw can be exemplified.

In the sealing device having such a structure, O
-When the pressing force on the ring is increased, the pressure from the O-ring to the gas flow pipe increases, and the gas flow pipe becomes difficult to move. If the pressing force on the O-ring is reduced, the gas flow pipe is likely to be displaced. For this reason, it is advantageous in that the pressing force on the O-ring can be adjusted so that the gas flow pipe can be easily moved according to the tensile stress or the compressive stress from the cell while maintaining the airtightness well. is there.

In the present invention, the gas flow pipe may be either a gas supply pipe or a gas discharge pipe. When oxidizing gas is used as one power generation gas, fuel gas is used as the other power generation gas, and when oxidizing gas is used as the other power generation gas, one gas is used as the power generation gas. Use fuel gas. According to these selections, the gas chamber for flowing one of the power generation gases is an oxidizing gas chamber or a fuel gas chamber.

In the present invention, for example, when a tensile stress is applied to the sealing portion between the cell and the gas flow pipe,
By moving the gas flow pipe, the stress on the seal portion can be reduced. However, when the static friction force between the gas flow pipe and the O-ring increases, the gas flow pipe may not be able to move quickly when the tensile stress is generated. If the static friction force is large, an excessive load may be applied to the seal portion. For example, when Pyrex glass is used for the seal portion, the sealing performance is exhibited by the softening of the glass, but the seal is broken by the above-mentioned excessive load. Also, for example, when a material that does not melt at the operating temperature is used as a sealing material, it is strong against compressive stress, but weak against tensile stress, even if not as weak as softened glass, and breaks the seal. There are cases.

For this reason, it is preferable to provide an urging means for urging the gas flow pipe toward the cell.
Thus, when a tensile stress is applied to the gas flow pipe, the gas flow pipe quickly moves toward the unit cell, and the tensile stress applied to the sealing portion can be easily reduced.

During operation, there may be a difference between the temperatures of the cells constituting the stack. For this reason, when the operation is stopped, some of the cells may contract significantly.
In addition, a gas-permeable elastic material such as nickel felt is usually interposed between adjacent cells. However, if the operation is continued for a long period of time, the nickel felt shrinks, and the position of each cell may shift from the initial position.

In such a case, by providing a tapered surface in the through hole of the partition wall through which the gas flow pipe penetrates, each gas supply pipe rotates in accordance with the relative position movement of each cell. In addition, the relative position movement of each cell can be absorbed. In this case, it is preferable that the tapered surface is particularly open toward the unit cell side. For the same reason, it is preferable that a tapered surface is provided in a through hole of the pressing member through which the gas supply pipe passes. In this case, it is particularly preferable that the tapered surface is open toward the side opposite to the cell side.

In the case where a plurality of gas passages are provided in the cell, a manifold member for airtightly joining the gas flow pipe to the cell is provided. It is preferable to connect a plurality of gas passages of the unit cell. Thus, gas can be supplied from a single manifold member to a plurality of gas passages of the unit cell.

The materials of the gas flow pipe and the manifold member are as follows:
It must have heat resistance, durability against oxidizing gas and fuel gas. As such a material, alumina, alumina-magnesia spinel, and zirconia are preferable.

These embodiments will be described in more detail with reference to FIGS.

FIG. 1 is a cross-sectional view of a unit cell 1 used in one embodiment of the present invention. FIG. 2 is a cross-sectional view showing a power generation device 8 using a stack 28 in which, for example, three unit cells of FIG. 1 are connected in series, and FIG. 3 is a longitudinal cross-sectional view of the power generation device 8 of FIG. FIG. 4 is a schematic cross-sectional view for explaining a sealing structure of the oxidizing gas supply pipe 18. First, the entire power generation device 8 will be described, and then details of the seal structure will be described.

Support 2 of unit cell 1 (1A, 1B, 1C)
Is composed of an air electrode plate 3 and a separator 4. The planar shape of the separator 4 is a rectangle. A pair of elongated side walls 4a are formed on the edge of the flat body of the separator 4 in the cross-sectional direction.
Are formed. Each of the side walls 4a has a quadrangular prism shape, and extends from one end in the longitudinal direction of the separator 4 to the other end.

Between the pair of side walls 4a, there are provided, for example, three rows of quadrangular prism-shaped partitions 4b. The partition walls 4b extend parallel to each other from one end of the separator 4 in the longitudinal direction to the other end. Parallel grooves are formed between the side walls 4a and the partition walls 4b, for example, in total of four rows.

The plane shape of the air electrode plate 3 is the same as the plane shape of the separator 4. A pair of elongated side walls 3a are formed at the edges of the flat plate body of the air electrode plate 3 in the cross-sectional direction, and a rectangular column-shaped partition wall 3b is formed between the pair of side walls 3a.
For example, three rows are provided. Between the side wall 3a and the partition wall 3b, parallel grooves are formed, for example, in a total of four rows.
Each side wall 4a of the separator 4 is joined to each side wall 3a of the air electrode 3, and each partition 4b of the separator 4
It is joined to each partition 3b of the air electrode plate 3. As a result, for example, four rows of oxidizing gas passages 5 are formed between the air electrode plate 3 and the separator 4.

The solid electrolyte membrane 6 has a main surface 3c of the air electrode 3,
The side surface 3d is covered, and further, the upper part of the width direction side surface 4d of the separator 4 is covered. The oxidizing gas passage 5 and the side surface 3d of the air electrode 3 are both surrounded by a separator 4 and a solid electrolyte membrane 6 which are airtight. The fuel electrode film 7 is formed on the solid electrolyte film 6. However, the unit cell to which the present invention can be applied is not limited to the embodiment shown in FIG.

By stacking the unit cells as shown in FIG. 1 and connecting them in series, the stack 2 shown in FIGS.
8. In the stack 28, for example, three unit cells 1A, 1B, and 1C are stacked. Each main surface 4c of each separator 4 of each unit cell 1A, 1B is in contact with each fuel electrode membrane 7 of each lower unit cell 1B, 1C.
Each is connected via a permeable conductive material 17.
Nickel felt and nickel sponge are preferable as the air-permeable conductive material.

The unit cells 1A of the stack 28 are connected to the current collecting plate 12A through the permeable conductive material 16, and the unit cells 1C are connected to the current collecting plate 12B through the conductive material 16. The stack 28 and the upper and lower current collectors 12A and 12B are housed in a predetermined airtight container. The form of this container is not limited. In the present embodiment, the container is formed by providing the heat insulating material layer 10 inside the metal outer shell 11.

In the container, a combustion area 30, a power generation area 36, a preheating chamber 19, and an oxidizing gas chamber 24 of the power generation chamber 15 are provided in this order from the left side in FIG. The stack 28 shown in the cross-sectional view of FIG.
The inside state is shown. The oxidizing gas chamber 24 and the preheating chamber 19 are separated from each other by an airtight partition 20.
And the power generation chamber 15 are also separated by an airtight partition 51.

An oxidizing gas supply pipe 18 is provided for each unit cell. The right end 18 c of each supply pipe 18 opens into the oxidizing gas chamber 24. Each supply pipe 18 penetrates the partition wall 20, the preheating chamber 19, and the partition wall 51, and is attached to one end 1a of each unit cell by a manifold member 42, respectively. 51a and 20a are through holes of each partition, respectively.

At the right supply side end 18c of each supply pipe 18, a sealing device 33 is provided to make the supply pipe 18 movable with respect to the partition wall 20 while maintaining airtightness. Further, a biasing means 21 is attached to each end 18c of each supply pipe.

Details of a preferred example of such a seal structure will be described with reference to FIG. The cell-side end 18b of the supply pipe 18 is airtightly attached to the cells 1A (1B, 1C) via a manifold member 42.

A sealing device 33 is provided on the partition wall 20. The sealing device 33 includes an O-ring 39 and a pressing plate 37 that presses each O-ring 39 toward the partition wall 20 with a predetermined pressure. Through hole 37a of pressing plate 37
The supply pipe 18 is inserted through. The pressing plate 37 is attached to the partition 20 by screws 38.
By changing the stop position of the screw 38, the pressing plate 3
7 controls the pressing force to the O-ring 39. Through hole 3
7a has a tapered surface 5 that opens toward the opposite side of the unit cell.
0 is provided.

A supply port 18d is provided at a supply side end 18c of the supply pipe 18, and an urging means 21 is attached. As a result, each supply pipe 18 is urged toward the corresponding unit cell at a constant pressure as indicated by an arrow J. With these configurations, stress concentration on the sealing portion at the boundary between the cell and the supply pipe is reduced.
Can be effectively alleviated.

The inventor has also studied using a so-called bellows to reduce the tensile stress between the unit cell and the supply pipe. In this case, for example, when a tensile stress is applied from the unit cell to the supply pipe as shown by an arrow R, the bellows contracts and absorbs the tensile stress. However, when the bellows contracts, the bellows naturally exerts an elastic restoring force for restoring the original shape, so that a tensile stress is applied from the bellows to the supply pipe. For this reason, when the bellows is severely deformed, the elastic restoring force applied from the bellows to the supply pipe increases, and the increased elastic restoring force tends to apply excessive stress to the sealing portion between the cell and the supply pipe. Was.

On the other hand, according to the present invention, the supply pipe 1
For example, when a tensile stress is applied to the supply pipe 8 and the supply pipe 18 moves in the direction of the arrow Q, no elastic restoring force acts on the supply pipe 18 from the sealing device 33 in that state.

The tapered surface 20 is formed in the through hole 20a of the partition wall 20.
b is provided, and the tapered surface 20b is formed so as to open toward the unit cell. Thereby, when the end portion 18b of the supply pipe 18 moves up and down, the supply pipe is easily rotated.

Next, the flow of each gas will be described. As shown in FIGS. 3 and 4, the oxidizing gas is supplied from the outside of the outer shell 11 through the supply port 26 to the oxidizing gas chamber 24 as indicated by an arrow B.
And flows into each supply pipe 18 as shown by an arrow K, for example, and flows through an inner space 18a of each supply pipe 18 as shown by an arrow C. Then, the gas enters each gas passage 5 of the unit cell from the end 18 b of the supply pipe 18 via the manifold member 42.
Then, it flows through each gas passage 5 and is discharged from the unit cell to the combustion region 30 as shown by the arrow D, where it reacts with the exhaust fuel gas.

The fuel gas is supplied from the outside of the outer shell 10 into the power generation chamber 15 as shown by the arrow E, flows between the cells and the gap between the cells and the container as shown by the arrow F, and flows in the combustion region. Flow into 30.

In the combustion zone 30, the depleted fuel gas is
Reacts with depleted oxidizing gas and burns. This combustion exhaust gas flows through the exhaust gas pipe 25 as shown by arrows G and H, is supplied into the preheating chamber 19, and is discharged from the preheating chamber 19 through the outlet 27 as shown by the arrow I. Due to the waste heat of the combustion exhaust gas, the inner space 18 of each supply pipe 18 is
The oxidizing gas flowing through a can be preheated.

FIG. 5 is a longitudinal sectional view showing a power generator 40 according to another embodiment of the present invention. The cross-sectional shape of the power generation device 40 is the same as that shown in FIG. The description of the components already described in FIG. 3 is omitted.

In this embodiment, the preheating chamber 19 shown in FIG.
And the oxidizing gas chamber 24 is adjacent to the power generation chamber 15. Therefore, the partition wall 20 includes the oxidizing gas chamber 24 and the power generation chamber 15.
The seal is between. On the other hand, on the oxidizing gas discharge side, an exhaust oxidizing gas chamber 43 is provided adjacent to the power generation chamber 15. The power generation chamber 15 and the exhaust gas chamber 43 are separated by an airtight partition 48.

An oxidizing gas discharge pipe 4 is connected to the discharge-side end 1b of each cell via a manifold member 42, respectively.
One end 41b is airtightly attached. Discharge pipe 4
1 passes through the power generation chamber and penetrates the through hole 48 a of the partition wall 48, and the end 41 c of the discharge pipe 41 is
3 is open.

The sealing device 44 is provided on the partition wall 48. Although the form of the sealing device 44 is not limited, preferably, as shown in FIG. 4, an O-ring 39 and a pressing plate 37 pressing each O-ring 39 toward the partition wall 48 with a predetermined pressure are provided. ing. By changing the stop position of the screw, the pressing force from the pressing plate to the O-ring can be controlled.

A biasing means 45 is provided at the end 41c of the discharge pipe 41.
Is attached. Thereby, each discharge pipe 41
At a constant pressure toward each corresponding cell.

Next, the flow of each gas will be described. The oxidizing gas is supplied from the outside of the outer shell 11 to the oxidizing gas chamber 24 via a supply port 26 as shown by an arrow B, and each supply pipe 18
Flows through the inner space 18a as indicated by the arrow C, and enters each gas passage 5 of the unit cell from the end 18b of the supply pipe 18 via the manifold member 42. Then, the gas flows through each gas passage 5, and passes through the corresponding discharge pipe 4 via the manifold member 42.
1 and flows through the inside space 41 a of the discharge pipe 41 as shown by the arrow M. Then, the gas flows into the exhausted oxidizing gas chamber 43 from the end 41c of each exhaust pipe 41, and is further exhausted to the outside of the container as indicated by an arrow N.

The fuel gas is supplied from the outside of the outer shell 10 into the power generation chamber 15 as shown by the arrow E, flows between the cells and the gap between the cells and the container as shown by the arrow F, and further flows by the arrow F. It is discharged out of the container like L.

[0047]

As described above, according to the present invention, in a power generator, a unit cell is joined to a gas flow pipe such as an oxidizing gas supply pipe so that airtightness can be maintained. In a structure in which gas and fuel gas are separated, preventing a decrease in airtightness between the unit cell and the oxidizing gas supply pipe,
A reduction in power generation efficiency and electromotive force can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a cell 1 that can be used in one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the power generation device 8.

FIG. 3 is a longitudinal sectional view schematically showing the power generator 8 of FIG.

FIG. 4 is a cross-sectional view for explaining a structure of a gas-tight sealing portion between a gas supply pipe 18 and a partition wall 20.

FIG. 5 is a longitudinal sectional view showing a power generator 40 according to another embodiment of the present invention.

[Explanation of symbols]

1, 1A, 1B, 1C cell, 3 air electrode plate, 4 separator, 5 oxidizing gas passage, 6 solid electrolyte membrane, 7
Fuel electrode membrane, 8, 40 power generation device, 12A, 12B current collector, 15 power generation chamber, 42 manifold member, 18 oxidizing gas supply pipe, 18a inner space of oxidizing gas supply pipe, 1
9 Preheating chamber, 20 Partition wall for maintaining gas tightness of gas supply pipe, 20a through hole, 20b tapered surface of through hole, 21
Gas supply pipe urging means, 24 oxidizing gas chamber, 28 unit cell stack, 30 combustion area, 33, 44 sealing device, 36 power generation chamber power generation area, 41 gas exhaust pipe, 41
a inner space of the gas discharge pipe, 45 urging means of the gas discharge pipe, 48 partition wall in which the gas discharge pipe maintains airtightness, 50
The tapered surface of the through hole 37a of the pressing member 37, B, C, D,
K, M, N Flow of oxidizing gas, E, F, L Flow of fuel gas, J Direction of energization of gas flow tube, direction of stress from R cell, direction of movement of Q gas flow tube

Continued on the front page (72) Inventor Yoshinori Sakaki 20-1 Kita-Sekiyama, Odaka-cho, Midori-ku, Nagoya-shi, Aichi Prefecture Inside Chubu Electric Power Co., Inc. (72) Inventor Junichi Fujita 3-3-1 Nakanoshima, Kita-ku, Osaka-shi, Osaka 22 Kansai Electric Power Co., Inc. (72) Inventor Shinji Takeuchi 3-2-2 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Inventor Shinji Kawasaki 2-56, Sudacho, Mizuho-ku, Nagoya-shi, Aichi Prefecture No. Japan Insulators Co., Ltd. (72) Kiyoshi Okumura, Inventor 2-56, Sudacho, Mizuho-ku, Nagoya, Aichi Prefecture Japan Insulators Co., Ltd. (72) Inventor Makoto Murai 2-56, Sudacho, Mizuho-ku, Nagoya, Aichi Prefecture No. Japan Insulators Co., Ltd.

Claims (6)

[Claims] 1. A power generator for a solid oxide fuel cell, comprising at least an air electrode, a fuel electrode, and a solid electrolyte, and having a gas passage for flowing one of the power generation gases. A cell of a solid oxide fuel cell, a gas flow pipe made of ceramics attached to the cell, and a gas flow pipe for supplying or discharging gas to the gas passage; A gas chamber for flowing the one power generation gas, a power generation chamber for accommodating the single cell and the other power generation gas, and separating the one power generation gas from the other power generation gas And the gas flow pipe is hermetically joined to the unit cell, the gas flow pipe penetrates the partition, and the gas chamber and the inner space of the gas flow pipe. And the gas passage And the gas flow pipe is sealed so as to be movable with respect to the partition wall while maintaining airtightness with respect to the partition wall. And a sealing device for sealing between the gas flow pipe and the partition wall. The seal device contacts the gas flow pipe and the partition wall.
2. The power generator according to claim 1, further comprising: a − ring, a pressing member that presses the O-ring toward the partition, and an adjusting unit that adjusts a pressing force of the O-ring against the partition. 3. apparatus. 3. The apparatus according to claim 1, further comprising: urging means for urging the gas flow pipe toward the cell.
The power generator according to claim 1. 4. The power generation device according to claim 1, wherein a tapered surface is provided in a through hole of said partition wall through which said gas flow pipe penetrates. apparatus. 5. The power generator according to claim 2, wherein a tapered surface is provided in a through hole of the pressing member through which the gas flow pipe penetrates. 6. A manifold member for airtightly joining said gas flow pipe to said unit cell, said unit cell being provided with a plurality of said gas passages, and said gas passage being provided by said manifold member. The power generator according to any one of claims 1 to 5, wherein the inner space of the tube and the plurality of gas passages of the unit cell communicate with each other.