JPH06203867A - Solid electrolyte fuel cell type power generator furnace - Google Patents

Abstract

PURPOSE:To provide a solid electrolyte fuel cell type power generator furnace in which a vertically positioned cell-stack can be supported inside a power reactor casing without generating large stress in the cell-stack. CONSTITUTION:Both end portions of a cell-stack 7 having cells 8 are supported to supporting members 1a, 3 located in a power reactor casing 1, and an expansion means 15 is provided around the power reactor casing 1 and between the supporting members 1a, 3. Since the cell-stack 7 is supported by the supporting members 1a, 3 at both ends, no great stress is generated therein. The difference in thermal expansion between the cell-stack 7 and the power reactor casing 1 is absorbed by the expansion means 15, so that no great thermal stress is generated in them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid oxide fuel cell 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. 4 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. This cell stack 7 has a lower closed end side supported on a bottom plate 1a forming a fuel gas chamber 6 of a power generation reactor casing 1, and an opening end side guide portion 9 at an upper part thereof formed in an air gas partition plate 3 It is positioned so as to pass through the portion 3a and face the second 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.
0 and the cell stack 7, an air flow path 11 is formed, and a fuel gas flow path 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. The generated air is collected in the second air chamber 5 and then discharged to the outside through the air discharge hole 5a, and the used fuel gas is discharged through the fuel gas discharge hole 6b in the fuel gas chamber 6. It is discharged to the outside.

[0006]

The electrochemical reaction through the solid electrolyte is carried out at a high temperature of about 1000 ° C., and the cell stack 7 is mainly composed of a perovskite-type lanthanum-based composite oxide or ceramics such as YSZ. On the other hand, since the power generation furnace casing 1 is mainly made of a metal such as Ni and has different thermal expansion coefficients, the cell stack 7 and the power generation furnace casing 1 have different thermal expansion amounts. Occurs. Therefore, the diameter of the hole 3a of the air partition plate 2 is made sufficiently larger than the outer diameter of the guide portion 9 of the cell stack 7, so that the cell stack 7 and the power generation furnace casing 1 can be freely set at the time of startup of the power generation furnace. It is capable of thermal expansion.

Therefore, the cell stack 7 has a one-end support structure in which only the lower end portion is supported on the power generation furnace casing 1 side, and there is a disadvantage that a large stress is generated at the lower end portion. Therefore, the strength of the material is small, about 1000
There has been a problem that deformation or cracking occurs on the closed end side of the cell stack 7 under a high temperature of ° C. Further, since there is a gap between the guide portion 9 of the cell stack 7 and the air gas partition plate 3, for example, the fuel gas on the high pressure side leaks into the second air chamber 5 side from this gap, and the hydrogen in the fuel gas There is a risk that the gas burns in the vicinity of the guide portion 9 of the cell stack 7 and the combustion heat destroys the cell stack 7 and the like.

On the other hand, as shown in FIG. 5, the periphery of the guide portion 9 of the cell stack 7 inserted into the hole 3a of the air-gas partition plate 3 is fixedly supported on the air-gas partition plate 3 without any gap. At the same time, if the lower end of the cell stack 7 is separated from the bottom plate 1a of the power generation furnace casing 1 so that the cell stack 7 can be thermally expanded freely, the above leakage of fuel gas does not occur. However, also in this case, since the cell stack 7 has a one-end support structure in which only the upper end side is supported by the power generation furnace casing 1 via the air-gas partition plate 3, there is a disadvantage that a large stress is generated at the upper end. there were.

The present invention has been made in view of the above circumstances, and a solid oxide fuel cell capable of supporting the cell stack positioned in the vertical direction in the power generation furnace casing without generating a large stress. The purpose is to provide a power generation reactor.

[0010]

In order to achieve the above-mentioned object, the present invention has a unit cell formed by sandwiching a solid electrolyte between a pair of electrodes, and air and fuel gas are flown in and out of the unit cell. In a solid oxide fuel cell power generation reactor in which a cell stack is supported by the power generation furnace casing in a state of being vertically positioned in the power generation furnace casing, both end portions of the cell stack are supported by a support member on the power generation furnace casing side. And supporting means around the power generation furnace casing between the support members, the expansion and contraction means for absorbing the difference in thermal expansion between the power generation furnace casing and the cell stack.

[0011]

[Function] Since both ends of the cell stack are supported by the supporting members on the side of the power generation furnace casing, both ends are supported,
The cell stack is supported without causing large stress. In this case, since the cell stack is positioned in the vertical direction, if both ends of the cell stack are supported by the supporting members, a difference in thermal expansion occurs between the cell stack and the power generation furnace casing, and a large thermal stress is applied to them. Although there is a possibility that it will occur, this thermal expansion difference is absorbed by the expansion and contraction means provided around the power generation furnace casing between the support members, so that large thermal stress does not occur in the cell stack or the power generation furnace casing.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. 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 each having a unit cell 8 are fixed to the bottom plate 1a of the power generation furnace casing 1 whose lower end is a closed end side and which is mainly made of metal such as Ni. Are positioned in the fuel gas chamber 6 in a state in which the air gas partition plate 3 is penetrated at the upper portion of the guide portion 9 side. Then, the air introduction pipe 10 whose upper end portion side penetrates the air partition plate 2 and opens to the first air chamber 4 is inserted into the cell stack 7 through the second air chamber 5, and the air introduction pipe 10 and the cell An air passage 11 is formed between the stacks 7, and a fuel gas passage 12 is formed in the fuel gas chamber 6 near the outer periphery of the cell stack 7. The first air chamber 4 has 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. 2 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. Since the air electrode 8b also has a role of a support tube for the unit cell 8, the air electrode 8b is thicker than the others.

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 upper and lower ends of the cell stack 7 are fixedly supported by the power generation furnace casing 1 itself and the supporting members supported by the casing. That is, the upper guide portion 9 of the cell stack 7 is supported with its outer peripheral surface side fixedly attached to the air-gas partition plate 3 supported by the power generation furnace casing 1 without any gap, and the lower end side of the cell stack 7 is supported. The closed end is fixedly supported on the bottom plate 1a which is a part of the power generation furnace casing 1.

Further, the thermal expansion amount of the cell stack 7 at the time of power generation and the air-gas partition plate 3 are provided around the power generation furnace casing 1 between the bottom plate 1a and the air-gas partition plate 3 which is the upper and lower support members of the cell stack 7. A metal bellows 14 having excellent heat resistance is attached as expansion and contraction means for absorbing a difference in thermal expansion amount of the power generation furnace casing 1 between the bottom plate 1a and the bottom plate 1a.
The bellows 14 is made of, for example, the same material as the power generation furnace casing 1 and has a gas-tight structure that does not cause gas leakage.

Therefore, even if the cell stack 7 and the fuel gas chamber 6 become hot during power generation and the strength of the cell stack 7 and the like decreases, the cell stack 7 is evenly supported at the two upper and lower locations. The load applied to the supporting portion of the cell stack 7 is halved, and no large stress is generated in the cell stack 7. Therefore, cracks do not occur in the fixed portion between the guide portion 9 of the cell stack 7 and the air partition plate 2, and the closed portion of the cell stack 7 is not deformed.

The cell stack 7 is mainly composed of a ceramic such as a perovskite-type lanthanum complex oxide or YSZ, and has a coefficient of thermal expansion higher than that of the power generation reactor casing 1 which is mainly composed of a metal such as Ni. Since it is small, a difference in thermal expansion occurs between the cell stack 7 and the generator casing 1, but this difference in thermal expansion is absorbed by the bellows 14, so both ends of the cell stack 7 are fixed to the generator casing 1 side. However, no thermal stress is generated in this cell stack 7.

In the above embodiment, the cell stack 7 is 1
The case where a plurality of unit cells 8 are provided has been described, but a case where a plurality of so-called vertical stripe type cell stacks 7 having a plurality of cylindrical unit cells 8 in the vertical direction are arranged in the fuel gas chamber 6 Good.

If the power generation furnace casing 1 is made of a material having a thermal expansion coefficient smaller than that of the cell stack 7, for example, the closed end side of the cell stack 7 must be fixed to the bottom plate 1a of the power generation furnace casing 1. Instead, the closed end side of the cell stack 7 may be placed on the bottom plate 1a of the power generation furnace casing 1 so that the cell stack 7 is supported by the bottom plate 1a.

FIG. 3 is a cross-sectional view of a solid oxide fuel cell type power generation reactor which is another embodiment of the present invention. In this power generation furnace, the inside of the power generation furnace casing 21 mainly made of metal such as Ni is provided with a first air gas partition plate 22 and a second air gas partition plate 23 fixed to the first air chamber 24 and fuel. The fuel gas chamber 25 is divided into a gas chamber 25 and a second air chamber 26, and a plurality of cylindrical cell stacks 27 each having a plurality of single cells 28 formed therein are vertically positioned. The cell stack 27 is composed of a plurality of cylindrical single cells 28 provided independently of each other and guide portions 29 and the like provided on both sides of the plurality of single cells 28. Of the guide portion 29 penetrates the first and second air-gas partition plates 22 and 23, and the outer peripheral surface side of the guide portion 29 is fixed to the first and second air-gas partition plates 22 and 23 without any gap therebetween. It is supported. The air flow path 3 is provided in the cell stack 27.
0 is formed, and a fuel gas passage 31 is formed near the outer peripheral surface of the cell stack 27.

In the unit cell 28, an air electrode and a fuel electrode are formed on the inner and outer surfaces of a cylindrical solid electrolyte, and an interconnector conducting to the air electrode is provided so as to project to the outside of the fuel electrode. The material and the shape of the components are the same as those of the unit cell shown in FIG. In addition, the adjacent cell stack 2
The single cells 28 of 7 are connected in series and parallel to each other via a conductive felt.

Further, between the first air gas partition plate 22 and the second air gas partition plate 23, there is N around the power generation furnace casing 21.
A bellows 32, which is a gas-tight expansion / contraction means composed of i and the like, is attached, and the bellows 32 allows the cell stack 27 and the first and second air-gas partition plates 2 to be attached.
The difference in thermal expansion between the power generation furnace casing 21 and the power generation furnace casing 21 is absorbed. Incidentally, 24a is an air supply hole,
25a is a fuel gas supply hole, 25b is a fuel gas discharge hole, 2
6a is an air discharge hole.

Therefore, also in this power generation furnace, the air supplied to the first air chamber 24 through the air supply hole 24a is introduced into the air flow passage 30 in the cell stack 27, and the fuel gas supply hole 25a is supplied. When the fuel gas supplied to the fuel gas chamber 25 via the fuel gas chamber 25 is introduced into the fuel gas passage 31 in the vicinity of the outer peripheral surface of the cell stack 27, oxygen gas in the air and hydrogen gas in the fuel gas are combined into a single cell 28. And reacts electrochemically through the solid electrolyte, and an electromotive force is generated in each single cell 28 in the cell stack 27. Then, as a whole of the power generation furnace, electric power corresponding to the number of cell stacks 27 is taken out for each single cell 28 of the cell stack 27. Then, the generated air is collected in the second air chamber 26, and then discharged to the outside through the air discharge hole 26a, and the generated fuel gas is discharged to the outside through the fuel gas discharge hole 25b.

In this case, since the cell stack 27 is evenly supported at the two upper and lower locations, the force applied to the supporting portion of the cell stack 27 is halved, and no large stress is generated in the cell stack 27 and the cell stack 27. Since the guide part 29 is attached to the first and second air-gas partition plates 22 and 23 without a gap, it is provided between the first air chamber 24 and the fuel gas chamber 25 and between the second air chamber 26 and the fuel gas chamber 25. There is no leakage of air or fuel gas. Further, in this case, a difference in thermal expansion occurs between the cell stack 27 and the power generation furnace casing 21 between the first and second air-gas partition plates 22 and 23, but since this difference in thermal expansion is absorbed by the bellows 32, Large thermal stress does not occur in the cell stack 27 or the like.

Each single cell 28 in the cell stack 27 is
May or may not be connected to each single cell 28 in the other cell stack 27. Furthermore, the single cells 28 in the cell stack 27 may be connected in series with each other, or the cell stack 27 may have only one single cell 28. Further, in this embodiment, the annular bellows is provided in one stage, but two or more stages may be provided.

[0028]

As is apparent from the above description, according to the present invention, both ends of the cell stack are supported by the supporting members on the side of the power generation furnace casing even when the cell stack is positioned vertically in the power generation furnace casing. In addition, since the expansion / contraction means provided in the power generation furnace casing absorbs the difference in thermal expansion between the cell stack and the power generation furnace casing, this cell stack can generate power without causing large stress in the cell stack. It can be supported in the furnace casing.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional plan view showing details around a single cell.

FIG. 3 is a cross-sectional front view of a solid oxide fuel cell power plant which is another embodiment of the present invention.

FIG. 4 is a sectional front view of a conventional solid oxide fuel cell power generation reactor.

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

[Explanation of symbols]

1 ... Power generation furnace casing, 1a ... Bottom plate (support member),
3 ... Air-gas partition plate (support member), 7 ... Cell stack, 8 ... Single cell, 8a ... Solid electrolyte, 8b ... Air electrode, 8c ... Fuel electrode, 14 ... Bellows (expanding / contracting means), 21 ... Power generation furnace casing, 22 ... 1st air-gas partition plate (support member), 23 ... 2nd air-gas partition plate (support member), 27 ... Cell stack, 28 ... Single cell, 32 ... Bellows (expansion-contraction means).

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

Claims (1)

[Claims] 1. A cell stack having a unit cell formed by sandwiching a solid electrolyte between a pair of electrodes, in which air and fuel gas are flown in and out, is vertically positioned in a power generation furnace casing. In the solid oxide fuel cell power generation reactor supported in this state in the power generation furnace casing, both ends of the cell stack are supported by the power generation furnace casing side support member, and the power generation reactor casing around the support members is surrounded. A solid oxide fuel cell type power generation furnace comprising expansion / contraction means for absorbing a difference in thermal expansion between the power generation furnace casing and the cell stack.