JPH06203858A - Solid electrolyte fuel cell type power generator furnace - Google Patents

Abstract

PURPOSE:To provide a solid electrolyte fuel cell type power generator furmace preventing gas from leaking from a partition wall between an air chamber and a fuel gas chamber allowing a cell-stack to pass through in a freely movable manner. CONSTITUTION:In a chamber with lower pressure, an air chamber 16 or a fuel gas chamber 6, a green compact 16 made from a perovskite lanthanum composite oxide is installed while cold with a predetermined distance L from a partition wall 3 and around that side of a cell-stack 7 toward which the partition wall 3 is moved by thermal expansion. At least that side 3a of the partition wall 3 which faces the green compact 16 is also made from the perovskite lanthanum composite oxide. When the power reactor is in steady operation at about 1000 deg.C the partition wall 3 approaches the green compact 16; when gas leaks from the space between the green compact 16 and the partition wall 3 and temperature rises the green compact 16 is connected to the partition wall 3 by sintering so that the space is blocked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell type power generation reactor using a solid electrolyte.

[0002]

2. Description of the Related Art A solid oxide fuel cell includes a solid electrolyte such as yttria-stabilized zirconia (YSZ) or calcia-stabilized zirconia (CSZ), and an air electrode made of, for example, a perovskite-type lanthanum complex oxide and nickel. Is provided, and the electromotive force is obtained by electrochemically reacting the air and the fuel gas, which flow toward each of the electrodes, with the fuel gas through the solid electrolyte. In this type of fuel cell, it is necessary to separate the fuel gas flow path and the air flow path into an airtight state.
For example, there is known one in which a solid electrolyte is formed in a cylindrical shape, and electric power is obtained by a cylindrical single cell in which the electrodes are provided on the inner and outer surfaces thereof. In this case, since the electric power obtained by a single cell is small, a plurality of cylindrical cell stacks having one or more single cells are arranged in the casing, and these are electrically connected in series or series-parallel to generate electric power. There are also many power generation reactors that I have tried to obtain.

FIG. 5 is a sectional view of a power generation furnace in which a plurality of cell stacks each having one unit cell are housed. In the figure, reference numeral 1 denotes a power generation furnace casing that forms the outer surface of the power generation furnace. An air partition plate 2 and an air gas partition plate 3 are fixed to the power generation furnace casing 1, and the inside of the power generation furnace casing 1 is By these, three chambers in the vertical direction, that is, the first air chamber 4, the second air chamber 5, and the fuel gas chamber 6 are provided.
It is divided into The first air chamber 4 is provided with an air supply hole 4a for supplying air for power generation, and the second air chamber 5
Is provided with an air discharge hole 5a for discharging generated air, and the fuel gas chamber 6 discharges a fuel gas supply hole 6a for supplying a fuel gas for power generation and a fuel gas used for power generation. A fuel gas discharge hole 6b is provided.

Reference numeral 7 in the drawing denotes a cell stack vertically positioned in the fuel gas chamber 6, and this cell stack 7 has an air electrode on the inner surface side of the cylindrical solid electrolyte and a fuel electrode on the outer surface side thereof. The formed unit cell 8 has a cylindrical shape, and the unit cell 8 formed on the upper end side of the unit cell 8 is insulated from the guide unit 9. The upper portion is opened as a whole, and the lower portion is It has a closed shape. The cell stack 7 has its lower closed end side supported on the bottom plate 1a forming the fuel gas chamber 6 of the power generation reactor casing 1, and the upper open end side guide portion 9 thereof penetrates the air gas partition plate 3 and 2 Positioned so as to face the air chamber 5 side. An air introducing pipe 10 penetrating the air partition plate 2 and extending downward is inserted into the cell stack 7 up to the vicinity of the closed end thereof, and an air flow is generated between the air introducing pipe 10 and the cell stack 7. A passage 11 is formed, and a fuel gas passage 12 is formed near the outer peripheral surface of the cell stack 7.

The air supplied from the air supply hole 4a into the first air chamber 4 is introduced into the air flow passage 11 in the cell stack 7 through the air introduction pipe 10, and the fuel gas supply hole 6a is formed.
When the fuel gas supplied from the inside into the fuel gas chamber 6 is introduced into the fuel gas passage 12 outside the cell stack 7, the unit cell 8
Oxygen gas in the air and hydrogen gas in the fuel gas electrochemically react with each other through the solid electrolyte therein to generate an electromotive force in the single cell 8, and a desired power is generated from the plurality of cell stacks 7. Taken out. Then, after the used air is collected in the second air chamber 5, it is discharged to the outside through the air discharge hole 5a, and the fuel gas that has been generated is discharged through the fuel gas discharge hole 6b of the fuel gas chamber 6. It is discharged to the outside.

Here, the electrochemical reaction via the solid electrolyte is carried out at a high temperature of about 1000 ° C., and the power generation furnace casing 1 and the cell stack 7 are also heated to this temperature.
In this case, the cell stack 7 is mainly composed of a ceramic such as a perovskite-type lanthanum-based composite oxide or YSZ, whereas the power reactor casing 1 is mainly composed of a metal such as Ni and has a coefficient of thermal expansion of each other. Because of the difference, the cell stack 7 and the power generation furnace casing 1 have different thermal expansion amounts. Therefore, a sufficient gap 13 is formed around the penetrating portion of the air partition plate 2 of the cell stack 7, and the cell stack 7 can be used at the time of startup of the power generation furnace.
The generator casing 1 and the generator casing 1 can be thermally expanded freely.

Further, in this case, since the pressure on the fuel gas side is generally larger than the pressure on the air side in such a power generation furnace, the fuel gas in the fuel gas chamber 6 passes through the gap 13 and the second air chamber 5 There is a disadvantage that hydrogen gas in the fuel gas leaks to the side and burns in the second air chamber 5 and the combustion heat destroys the guide portion 9 of the cell stack 7 and the air gas partition plate 3 in the vicinity thereof. There was a risk of it occurring.

Therefore, conventionally, the gap 13 is sealed by filling the gap 13 with a heat-resistant glass fiber 14 or the like.

[0009]

However, even if the glass fiber 14 is filled in the gap 13 around the penetrating portion of the air-gas partition plate 3 of the cell stack 7 and the gap 13 is closed, the fuel gas in the fuel gas chamber 6 remains If the pressure difference with the air in the second air chamber 5 is large, the disadvantage that the fuel gas leaks from the gap between the glass fibers 14 to the second air chamber 5 side occurs. It is also conceivable that the gap 13 between the cell stack 7 and the air-gas partition plate 3 is filled with a ceramic adhesive to close the gap 13, but in this case, the power generation furnace casing 1 and the cell stack 7 are mutually This action of the gap 13 that escapes thermal expansion is lost, which is not preferable.

The present invention has been made in view of the above circumstances, and a solid electrolyte capable of effectively preventing a gas leak from occurring through a partition wall between an air chamber and a fuel gas chamber through which the cell stack movably extends. A fuel cell type power reactor is provided.

[0011]

In order to achieve the above-mentioned object, the first invention of the present invention has a unit cell formed by sandwiching a solid electrolyte between a pair of electrodes, and air and In a solid oxide fuel cell power generation reactor in which a cell stack in which fuel gas is flowed penetrates a partition wall between the air chamber and the fuel gas chamber and is movably positioned with respect to the partition wall, the air chamber and the fuel gas In the low pressure chamber side of the chamber, around the cell stack on the side where the partition walls relatively move with respect to the cell stack due to thermal expansion, a green compact composed of a perovskite-type lanthanum-based complex oxide is cold. It is characterized in that the partition wall is attached at a predetermined distance from the partition wall, and at least the side of the partition wall facing the green compact is made of a perovskite-type lanthanum complex oxide.

A second invention of the present invention has a unit cell formed by sandwiching a solid electrolyte between a pair of electrodes, and a cell stack in which air and fuel gas are flowed in and out of the unit cell is an air chamber and a fuel. In a solid oxide fuel cell power generation reactor that penetrates a partition with a gas chamber and is movably positioned with respect to the partition, a guide portion of a cell stack that penetrates the partition is made of a perovskite-type lanthanum-based composite oxide. In addition to the above, a powder compact made of a perovskite-type lanthanum-based complex oxide is attached to the surface of the partition wall in the air chamber and the fuel gas chamber on the low-pressure chamber side so as to surround the guide portion of the cell stack. It is characterized by that.

[0013]

According to the first aspect of the present invention, when the operation of the power generation furnace is started and the internal temperature rises, the partition wall between the air chamber and the fuel gas chamber becomes a cell due to thermal expansion of the power generation furnace casing or the like. It moves toward the green compact attached to the stack. If the distance between the partition wall and the green compact during cold is set equal to the amount of movement of the partition wall due to thermal expansion, the green compact and the partition wall will come into contact with each other during steady operation at about 1000 ° C. Then, when air or fuel gas leaks from the air gap of the green compact or the gap between the green compact and the partition wall to the low pressure chamber side of the air chamber and the fuel gas chamber where the green compact is located, combustion of the fuel gas occurs there. As a result, the temperature rises. In this case, since both the green compact and the side of the partition wall facing the green compact are made of perovskite-type lanthanum-based composite oxide, the temperature rise due to the combustion causes sintering of the green compact itself and between the green compact and the partition wall. Occurs, and these voids and gaps are closed.

According to the second aspect of the present invention, the powder compact is attached to the surface of the partition wall on the low pressure chamber side of the air chamber and the fuel gas chamber so as to surround the guide portion of the cell stack penetrating the partition wall. Therefore, when the operation of the power generation furnace is started and the internal temperature rises, the green compact moves together with the partition wall due to the thermal expansion of the power generation furnace casing and the like regardless of the thermal expansion of the cell stack. Then, the power generation furnace enters a steady operation at about 1000 ° C., and the low pressure chamber side of the air chamber and the fuel gas chamber where the powder compact is present, from the void of the powder compact itself or the gap between the powder compact and the guide portion of the cell stack. When air or fuel gas leaks into the air, combustion of the fuel gas occurs and the temperature rises. in this case,
Since the green compact and the guide part of the cell stack are made of perovskite-type lanthanum-based composite oxide, the temperature rise around the green compact causes sintering of the green compact itself and between the green compact and the guide part of the cell stack. Occurs, and these voids and gaps are closed.

[0015]

Embodiments of the present invention will now be described with reference to FIGS. FIG. 1 is a cross-sectional view of a solid oxide fuel cell power generation reactor which is an embodiment of the present invention, and the basic configuration of this power generation reactor is the same as that shown in FIG.

That is, in this power generation furnace, a plurality of cell stacks 7 in which unit cells 8 are formed are supported at their closed end sides on the bottom plate 1a of the power generation furnace casing 1 mainly made of metal such as Ni. Is positioned in the fuel gas chamber 6 with the upper guide portion 9 side thereof penetrating the air gas partition plate 3. In this case, a gap 13 for escape of thermal expansion is formed around the penetrating portion of the air-gas partition plate 3 of the cell stack 7. And the upper end side is the air partition plate 2
Is introduced into the cell stack 7 through the second air chamber 5 and the air flow path 11 is formed between the air introduction pipe 10 and the cell stack 7. A fuel gas passage 12 is formed in the fuel gas chamber 6 near the outer periphery of the cell stack 7 while being formed. The first air chamber 4 is provided with an air supply hole 4a, the second air chamber 5 is provided with an air discharge hole 5a, and the fuel gas chamber 6 is provided with a fuel gas supply hole 6a and a fuel gas discharge hole 6b.

FIG. 3 shows a cross section of a unit cell 8 of the cell stack 7. The unit cell 8 is formed on a cylindrical solid electrolyte 8a made of, for example, YSZ, and on the inner surface side of the solid electrolyte 8a, for example, a perovskite. -Shaped lanthanum-based complex oxide, cylindrical air electrode 8b, and solid electrolyte 8
a cylindrical fuel electrode 8c formed on the outer surface side of a and composed of, for example, Ni—ZrO ₂ cermet, and an air electrode 8
The upper and lower interconnectors 8d are electrically connected to the fuel cell b and project outward from the fuel electrode 8c and are formed of, for example, a perovskite-type lanthanum-based composite oxide.

In this case, the interconnector 8d and the air electrode 8b of the unit cells 8 of the cell stack 7 which are adjacent to each other in the left-right direction are electrically connected in series via the conductive felt 13, and are adjacent in the front-rear direction. The fuel cells 8c of the unit cells 8 of the cell stack 7 are electrically connected in parallel via the conductive felts 13, and the unit cells 8 of the plurality of cell stacks 7 are connected in series / parallel as a whole. It is composed.

In this embodiment, the perovskite-type lanthanum system is provided around the guide portion 9 protruding toward the second air chamber 5 side of the cell stack 7 while keeping a certain distance L from the air-gas partition plate 3 in the cold state. A ring-shaped sealing member 16 made of a composite oxide powder compact is attached without a gap. Further, the air-gas partition plate 3 as a whole or at least the surface side 3a on which the seal member 16 is disposed is made of a perovskite-type lanthanum-based complex oxide.

Next, the operation of the seal member 16 and the like will be described. During operation of the power generation furnace, both the cell stack 7 and the power generation furnace casing 1 forming the fuel gas chamber 6 having the cell stack 7 have substantially the same temperature. Mainly Ni
Since the power generation furnace casing 1 made of a metal such as the above has a large thermal expansion coefficient, the thermal expansion amount of the power generation furnace casing 1 is larger than that of the cell stack 7 at the time of startup of this power generation furnace, and the air gas is generated against the cell stack 7. The partition plate 3 will gradually move to the second air chamber 5 side. Therefore, the distance L of the seal member 16 attached to the guide portion 9 of the cell stack 7 from the air-gas partition plate 3 when the cell stack 7 is cold is set to the air-gas partition plate 3 relative to the cell stack 7.
If it is stored in the same length as the moving amount of
When a steady operating condition of 000 ° C is reached, the seal member 1
6 and the air-gas partition plate 3 are in contact with each other.

On the other hand, at the time of start-up of the power generation furnace, the fuel gas in the fuel gas chamber 6 leaks into the second air chamber 5 side from the gap 13 around the penetrating portion of the air gas partition plate 3 of the cell stack 7. Since the temperature inside the furnace is still low, no problem occurs. Then, when the temperature inside the power generation furnace approaches a steady operating state of about 1000 ° C., the seal member 16 comes into contact with the air-gas partition plate 3, so that the fuel gas leaks to the second air chamber 5 side. Although the amount also decreases, even in this case, fuel gas leaks into the second air chamber 5 through the gap between the seal member 16 and the air-gas partition plate 3. In this case, when the fuel gas leaks to the second air chamber 5 side and the hydrogen gas in the fuel gas burns, the temperature around the seal member 16 is about 12
Since the temperature rises to about 00 ° C, as shown in Fig. 2,
The seal member 16 itself at the portion where the fuel gas leaks and the air gas partition plate 3 are sintered, and the seal member 16
And the air-gas partition plate 3a are closed, and the gap of the seal member 16 itself is also closed.

Therefore, after a short time has passed from the steady operation of the power generation furnace, the gap between the seal member 16 and the air-gas partition plate 3 is closed, and the fuel gas leaks to the fuel gas chamber 6 side. There will be no congestion. Further, thereafter, even if a gap occurs between the seal member 16 and the air-gas partition plate 3 and the fuel gas leaks, this gap is immediately closed by the sintering of the seal member 16 and the air-gas partition plate 3. Become.
Furthermore, since the perovskite-type lanthanum-based composite oxide is chemically stable in a high-temperature redox atmosphere, the sealing member 16 does not deteriorate during operation and lose its sealing property.

The pressure in the second air chamber 5 is higher than that in the fuel gas chamber 6, and the thermal expansion amount of the power generation furnace casing 1 is smaller than that of the cell stack 7. When the plate 3 moves relatively to the fuel gas chamber 6 side, the seal member 16 is attached to the air gas partition plate 3
It may be mounted in the guide portion 9 of the cell stack 7 on the side of the fuel gas chamber 6 without a gap in a state of being separated by a predetermined distance L from.

FIG. 4 is a cross-sectional view of a solid oxide fuel cell power generation reactor which is another embodiment of the present invention. In this power generation reactor, as shown in FIG. 4A, a ring-shaped seal member 17 made of a green compact of perovskite-type lanthanum-based complex oxide is provided in the second air chamber 5 and the fuel gas chamber 6. And the cell stack 7 on the side of the low pressure chamber (in this case, the second air chamber 5)
It is mounted on the air-gas partition plate 3 around the guide part 9 without any space, and the guide part 9 of the cell stack 7 is also made of a perovskite-type lanthanum complex oxide. It should be noted that the seal member 17 and the guide portion 9 of the cell stack 7 are formed with a small gap so that the cell stack 7 can move during thermal expansion.

Next, the operation of the seal member 17 and the like will be described. When the operation of the power generation furnace is started and the temperature of the cell stack 7 and the power generation furnace casing 1 rises, the seal member 17 causes the air-gas partition plate 3 to move along with the thermal expansion of the power generation furnace casing 1.
And the cell stack 7 also moves with the sealing member 17
Thermally expands regardless of. During this period, in this power generation furnace, the fuel gas leaks from the fuel gas chamber 6 side to the second air chamber 5 side through the gap between the seal member 17 and the guide portion 9 of the cell stack 7 and the gap of the seal member 17 itself. However, when the temperature inside the power generation furnace reaches the vicinity of 1000 ° C., the temperature around the seal member 17 rises up to about 1200 ° C. due to the combustion of the leaked fuel gas, so that FIG.
As shown by, the seal member 17 and the like in the portion where the fuel gas leaks is sintered, the gap between the seal member 17 and the guide portion 9 of the cell stack 7 is closed, and the gap of the seal member 17 itself is also formed. It is blocked and the fuel gas is prevented from leaking from the fuel gas chamber 6 side to the second air chamber 5 side.

When air leaks from the second air chamber 5 side to the fuel gas chamber 6 side, the seal member 17 is provided with an air gas partition plate around the guide portion 9 of the cell stack 7 in the fuel gas chamber 6. It should be attached to 3 without a gap.

Therefore, in the case of this embodiment, the seal member 17 is provided in the air chamber 5 and the fuel gas chamber 6 regardless of the relative movement direction of the air-gas partition plate 3 with respect to the cell stack 7.
It is only necessary to place it on the low pressure chamber side, and the applicable range of the power generation furnace becomes wider than in the case of the above embodiment. Further, since the seal member 17 can be positioned so as to close the gap 14 between the air-gas partition plate 3 around the guide portion 9 of the cell stack 7 even when it is cold, gas leakage at the time of start-up can be reduced accordingly. it can.

[0028]

As is apparent from the above description, according to the first aspect of the present invention, the partition wall is relatively expanded by thermal expansion with respect to the cell stack on the low pressure chamber side of the air chamber and the fuel gas chamber. Around the cell stack on the moving side, a green compact composed of a perovskite-type lanthanum-based composite oxide was attached at a predetermined distance from the partition wall during cold, and at least the side of the partition wall facing the green compact was perovskite-type. Since it is composed of lanthanum-based composite oxides, when the power generation furnace enters steady operation at about 1000 ° C, gas leakage causes sintering of the green compact itself or between the green compact and the partition wall. The void of the powder itself or the gap between the green compact and the partition wall is closed, and gas leakage from the gap between the cell stack and the partition wall through which the cell stack penetrates is prevented. In this case, the perovskite-type lanthanum-based composite oxide is chemically sufficiently stable in a redox atmosphere at high temperature and can maintain the above-mentioned sealed state for a long period of time.

According to the second aspect of the present invention, the guide portion of the cell stack that penetrates the partition wall is made of a perovskite-type lanthanum-based composite oxide, and the partition wall is located in the low pressure chamber side of the air chamber and the fuel gas chamber. Since a powder compact composed of a perovskite-type lanthanum-based complex oxide is attached to the surface of the cell stack so as to surround the guide part of the cell stack, a gas leak will occur at the stage when the power generation furnace enters steady operation at about 1000 ° C. Along with this, sintering occurs between the green compact itself and between the green compact and the cell stack, and the voids between the green compact itself and the gaps between the green compact and the guide part of the cell stack are closed, resulting in the cell stack and the cell stack. Gas leaks from the gaps between the partition walls penetrating therethrough are prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a solid oxide fuel cell power plant which is an embodiment of the present invention.

FIG. 2 is an operation explanatory view around a seal member.

FIG. 3 is a sectional view of a single cell or the like.

FIG. 4 is an operation explanatory view around a seal member of a solid oxide fuel cell power plant which is another embodiment of the present invention.

FIG. 5 is a cross-sectional view of a conventional solid oxide fuel cell power generation reactor.

[Explanation of symbols]

3 ... Air gas partition plate (partition wall), 5 ... 2nd air chamber (air chamber), 6 ... Fuel gas chamber, 7 ... Cell stack, 8 ...
Single cell, 8a ... Solid electrolyte, 8b ... Air electrode (electrode) 8c ... Fuel electrode (electrode), 9 ... Guide part, 16
... Seal member (compacted powder), 17 ... Seal member (compacted powder).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takenori Nakajima 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Ltd.

Claims (2)

[Claims] 1. A cell stack having a unit cell formed by sandwiching a solid electrolyte between a pair of electrodes, and a cell stack in which air and fuel gas are flown in and out of the unit cell penetrates a partition wall between the air chamber and the fuel gas chamber. In a solid oxide fuel cell power generation reactor movably positioned with respect to the partition wall, the partition wall faces the cell stack by thermal expansion on the low pressure chamber side of the air chamber and the fuel gas chamber. Around the cell stack on the moving side, a green compact composed of a perovskite-type lanthanum-based composite oxide is attached at a predetermined distance from the partition wall when cold, and the partition wall faces at least the green powder body. A solid oxide fuel cell power generation reactor characterized in that its side is composed of a perovskite-type lanthanum-based composite oxide. 2. A cell stack having a unit cell formed by sandwiching a solid electrolyte between a pair of electrodes, and a cell stack through which air or fuel gas flows, penetrates a partition wall between the air chamber and the fuel gas chamber. In a solid oxide fuel cell power generation reactor which is movably positioned with respect to the partition wall, the guide portion of the cell stack penetrating the partition wall is composed of a perovskite type lanthanum-based composite oxide, and the air of the partition wall is Solid electrolyte type characterized in that a green compact composed of a perovskite-type lanthanum-based complex oxide is attached to the surface of the low pressure chamber side of the chamber and the fuel gas chamber so as to surround the guide portion of the cell stack. Fuel cell power generation reactor.