JP3389482B2 - Solid oxide fuel cell - Google Patents

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, and more particularly to a solid oxide fuel cell in which a combustion chamber partition plate is used to form a combustion chamber and a reaction chamber.

[0002]

2. Description of the Related Art As shown in FIG. 1, a solid oxide fuel cell has a reaction chamber 51 in which an air chamber partition plate 61, a combustion chamber partition plate 63, and a fuel gas chamber partition plate 55 are used. A combustion chamber B, a reaction chamber C, and a fuel gas chamber D are formed.

A plurality of bottomed cylindrical solid oxide fuel cell units 52 housed in a reaction vessel 51 are composed of a combustion chamber partition plate 6.
It is inserted and fixed in the cell insertion hole formed in No. 3, and one end of an air introduction pipe 59 fixed to the air chamber partition plate 61 is inserted into the inside thereof.

The combustion chamber partition plate 63 is formed with a fuel gas ejection hole for introducing an excess fuel gas into the combustion chamber B, and the fuel gas chamber partition plate 55 stores the fuel gas in the reaction chamber C.
A supply hole for supplying the inside is formed.

Further, in the reaction vessel 51, for example, a fuel gas introduction port 53 for introducing a fuel gas composed of hydrogen, an air introduction port 57 for introducing air, and an exhaust port for discharging the gas burned in the combustion chamber B. 67 is formed.

In such a solid oxide fuel cell, the air from the air chamber A is supplied into the solid oxide fuel cell 52, and the fuel gas from the fuel gas chamber D is supplied to a plurality of solid oxide fuel cells. It is supplied between the battery cells 52, reacted in the reaction chamber C, burns excess air and fuel gas in the combustion chamber B, and the burned gas is discharged to the outside from the exhaust port 67.

By the way, in the solid oxide fuel cell, since two types of gas, air and fuel gas, are used to generate electricity, it is necessary to prevent adverse effects due to gas leakage. Therefore, as described above, the air chamber partition plate 61 for configuring the combustion chamber B, the combustion chamber partition plate 63 of the cell 52, and the fuel gas chamber partition plate 55 are provided, and each chamber is configured, The gases introduced into these chambers are controlled. That is, the air chamber partition plate 61 and the air introduction pipe 5
9 so that air does not leak into the combustion chamber B from the fixed portion with 9, and fuel gas does not leak into the combustion chamber from the fixed portion between the combustion chamber partition plate 63 and the cell 52. 61, combustion chamber partition plate 63, fuel gas chamber partition plate 5
It is necessary to prevent the gas from leaking between the outer peripheral surface of 5 and the inner wall surface of the reaction vessel 51. In particular, it is necessary to pay sufficient attention to the airtightness of the combustion chamber partition plate 63.

However, various materials such as ceramics and metals are used for the solid oxide fuel cell, and the operating temperature of the solid oxide fuel cell is as high as about 1000 ° C., so that the heat between the members is increased. When the expansion coefficient is different and the air chamber partition plate 61, the combustion chamber partition plate 63, and the fuel gas chamber partition plate 55 are closely joined to the cell 52, the air introduction pipe 59, the reaction container 51, etc., the cell 52, the air introduction pipe 59, etc. There was a risk of damage.

Therefore, conventionally, as the air chamber partition plate 61, the combustion chamber partition plate 63, and the fuel gas chamber partition plate 55, alumina fibers are used so as not to damage the cells 52, the air introduction pipes 59, etc. from the viewpoint of the coefficient of thermal expansion. A heat-insulating board hardened with a binder was used. FIG. 7 shows a state in which the cells 52 are fixed by using the combustion chamber partition plate 63 made of a heat insulating board.

[0010]

However, the heat insulation board is soft because it is made of only alumina fibers which are hardened with a binder and has flexibility. As shown in FIG. 7, the combustion chamber partition plate composed of the heat insulation board is used. When 63 is used, a gap is created between the outer peripheral surface of the cell and the combustion chamber partition plate 63, fuel gas leaks into the combustion chamber B from that portion, combustion occurs near the cell, and the vicinity of the cell is heated. There was a risk that the cells would be damaged and damaged. Further, there is a problem that the fuel efficiency is deteriorated due to the leakage of the fuel gas and the power generation performance is deteriorated.

Further, since the combustion chamber partition plate 63 is made of alumina fibers only hardened with a binder, the air supplied to the combustion chamber B leaks into the reaction chamber C through the combustion chamber partition plate 63. However, there was a risk that combustion would occur in the reaction vessel.

It is an object of the present invention to provide a solid oxide fuel cell which can prevent leakage of fuel gas and air and thereby improve power generation performance.

In the solid oxide fuel cell of the present invention, a combustion chamber partition plate is used in the reaction container to form a combustion chamber and a reaction chamber.
A plurality of bottomed cylindrical solid oxide fuel cell units are inserted into and fixed in a plurality of cell insertion holes formed in the combustion chamber partition plate, and air is supplied into the solid oxide fuel cell units. And, a fuel gas is supplied between the solid oxide fuel cell units in the reaction chamber to cause a reaction,
Excess fuel gas is ejected into the combustion chamber from the fuel gas ejection holes formed in the combustion chamber partition plate, and the solid electrolyte
A solid oxide fuel cell for reacting with the air discharged from the inside of the fuel cell of the fuel cell to burn the fuel.
The combustion chamber partition plate is formed of a pair of ceramic plates that are opposed to each other at a predetermined interval, and the outer peripheral portion of the solid oxide fuel cell between the ceramic plates is filled with fibrous ceramics. The gap between the outer peripheral surface of the plate and the inner wall surface of the reaction vessel is filled with fibrous ceramics. Here, it is desirable that the fibrous ceramics contain Al ₂ O ₃ as a main component and the content of SiO ₂ be 40% by weight or less.

[0014]

In the solid oxide fuel cell of the present invention, the combustion chamber partition plates are formed of a pair of ceramic plates opposed to each other at a predetermined interval, and the fibers are provided on the outer periphery of the solid oxide fuel cell between the ceramic plates. Since the fibrous ceramics were filled in the gap between the outer peripheral surface of the combustion chamber partition plate and the inner wall surface of the reaction vessel while filling the ceramics, it is possible to reliably partition the inside of the reaction vessel into the combustion chamber and the reaction chamber.
Not only is it possible to prevent unnecessary gas from leaking out, but since there is no joint between the combustion chamber partition plate and the cell or the inner wall surface of the reaction vessel, even if the coefficient of thermal expansion is slightly different, Almost no stress acts, and it is possible to prevent damage to cells and the like.

Further, since the combustion chamber partition plate has a two-layer structure, it is possible to suppress the transfer of heat in the combustion chamber to the cells in the reaction chamber and prevent the cells from being broken due to the temperature difference.

Further, fibrous ceramics are mixed with Al ₂ O.
It is desirable that the main component is ₃ , and the content of SiO ₂ is 40% by weight or less. This makes it possible to mold the alumina fiber into a board by containing SiO ₂ , but on the other hand, it is not possible to use air or fuel. SiO ₂ component into the gas is mixed, SiO ₂ component is attached to the air electrode and the fuel electrode of the cell, but there is a possibility to deteriorate the power generation characteristics, that the content of SiO ₂ is 40 wt% or less As a result, the content of SiO ₂ component in the air or fuel gas is suppressed, and the power generation characteristics can be improved.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The solid oxide fuel cell of the present invention has substantially the same structure as the conventional one except for a structure for preventing leakage of air and fuel gas. The solid oxide fuel cell of the present invention will be described with reference to FIG. In the case of a structure similar to the structure described in the related art, the same reference numeral as that in the related art is given.

That is, as shown in FIG. 1, the solid oxide fuel cell is constructed by arranging a cylindrical solid oxide fuel cell 52 having a bottom in a reaction container 51. For example, a fuel gas inlet 53 for introducing a fuel gas composed of hydrogen, a fuel gas chamber partition plate 55 for dispersing the fuel gas, an air inlet 57 for introducing air, and air are introduced into the cell 52. It is composed of an air introducing pipe 59, an air chamber partition plate 61 fixing the air introducing pipe 59, and a combustion chamber partition plate 63 fixing the cell 52.

Dispersion holes (not shown) for dispersing the fuel gas between the cells 52 are formed in the fuel gas chamber partition plate 55. Between the air chamber partition plate 61 and the combustion chamber partition plate 63 that fixes the cell 52, there is a combustion chamber B in which air and hydrogen burn.
As shown in FIG. 2 (b), the combustion chamber partition plate 63 is formed with the fuel gas ejection holes 83 for introducing the fuel gas passing between the cells 52 into the combustion chamber B. The gas burned in (1) is discharged to the outside through the exhaust port 67 provided in the reaction vessel 51.

The cell 52 is inserted into a cell insertion hole formed in the combustion chamber partition plate 63, and the combustion chamber partition plate 63 is formed with an introduction hole for introducing an excess combustion gas into the combustion chamber B. There is. The air introduction pipe 59 is inserted into an air introduction pipe insertion hole formed in the air chamber partition plate 61. The cell insertion hole of the combustion chamber partition plate 63 has a diameter 0.5 smaller than the outer diameter of the cell 52.
~ 3mm larger is better.

The cell 52 is, for example, as shown in FIG.
LaMnO ₃ system air electrode 71 as a support tube, solid electrolyte 72 formed of Y ₂ O ₃ stabilized ZrO ₂ formed on the surface of this air electrode 71, and Ni-zirconia system formed on the surface of solid electrolyte 72 Of the fuel electrode 73 and an interconnector 74 of LaCrO ₃ system electrically connected to the air electrode 71.

Then, as shown in FIG. 4, one cell 5
The second interconnector 74 is connected to the fuel electrode 73 of the other cell 52 via the connecting member 75 such as Ni metal fiber to the fuel electrode 73 of the other cell 52 to electrically connect the plurality of cells 52. The stack 77 is configured, and as shown in FIG. 1, a plurality of such stacks 77 are housed in the reaction vessel 51 to configure the solid oxide fuel cell. In the reaction vessel 51, an electrode 78 connected to the interconnector 74 of one cell 52 and an electrode (not shown) connected to the fuel electrode 73 of the other cell 52 are arranged. Power is extracted via 78.

In the solid oxide fuel cell of the present invention, as shown in FIG. 2 (c), the combustion chamber partition plate 63 is formed by a pair of ceramic plates 79 and 80, and the space between the ceramic plates 79 and 80. Fibrous ceramics 82 is filled in the outer peripheral portion of the solid oxide fuel cell unit 52. Fibrous ceramics 82 is also filled between the cell insertion holes formed in the ceramics plates 79 and 80 and the outer surface of the cell 52. Further, the fibrous ceramics 82 is also filled in the gap between the outer peripheral surface of the combustion chamber partition plate 63 and the inner wall surface of the reaction vessel 51.

Further, the fuel gas chamber partition plate 55 is also formed of a ceramic plate, and the fibrous ceramics 82 is filled in the gap between the outer peripheral surface of the fuel gas chamber partition plate 55 made of this ceramic plate and the inner wall surface of the reaction vessel 51. ing. The air chamber partition plate 61 is formed of a conventional heat insulating board, and the fibrous ceramics 82 is filled in the gap between the outer peripheral surface of the air chamber partition plate 61 and the inner wall surface of the reaction vessel 51. .

This fibrous ceramic 82 is made of Al ₂ O.
_The main component is ₃ , and the content of SiO ₂ is 40% by weight or less. Although this can be fiberizing by containing SiO _2, larger than 40 wt%, the SiO ₂ component is mixed with the air and fuel gas, the SiO ₂ component is attached to the air electrode and the fuel electrode of the cell However, the power generation characteristics may be deteriorated. SiO ₂ content is 10
5 from the point that performance deterioration after 00 hours is less than 3%
It is preferably less than or equal to wt%.

In the power generation of such a solid oxide fuel cell, air is introduced from the air introduction port 57 into the cell 52 through the air introduction pipe 59, and hydrogen is introduced from the fuel gas introduction port 53. This is performed by dispersing the fuel gas in the fuel gas chamber partition plate 55 through the dispersion holes and introducing the dispersed gas into the outside of the cell 52. The surplus air and the fuel gas are burned in the combustion chamber B and discharged from the exhaust port 67 to the outside. .

FIG. 5 shows the gas flow of one solid oxide fuel cell unit. Hydrogen gas (fuel gas) is introduced from the lower side of the fuel cell and is oxidized by power generation and proceeds upward. On the other hand, air (oxidizing gas) is introduced from above the cell to below the inside of the cell via the air introduction pipe 59. Then, it flows from the lower part inside the cell to the upper part. The air discharged from the upper part of the cell reacts with the hydrogen gas that has not been consumed in the power generation, and burns in the combustion chamber B.

In the solid oxide fuel cell configured as described above, the combustion chamber partition plate 63 is formed by a pair of dense ceramic plates 79 and 80, and the solid electrolytic fuel between the ceramic plates 79 and 80 is formed. Battery cell 52
Since the fibrous ceramics 82 is filled in the outer peripheral portion and the fibrous ceramics 82 is also filled in the gap between the outer peripheral surface of the combustion chamber partition plate 63 and the inner wall surface of the reaction vessel 51, the combustion chamber B in the reaction vessel 51 is filled. And the reaction chamber C can be reliably partitioned, and unnecessary gas leaks, for example, fuel gas leaks into the combustion chamber B from the cell insertion hole, and air reaction chamber C from the combustion chamber partition plate 63 itself. It is possible to prevent leakage into the interior, and since the combustion chamber partition plate 63 and the cell 52 and the inner wall surface of the reaction vessel 51 are not joined, even if the coefficient of thermal expansion is slightly different, Almost no stress acts on the member, and damage to the cell or the like can be prevented.

Further, since the combustion chamber partition plate 63 has a two-layer structure, it is possible to suppress the transfer of heat in the combustion chamber B to the cells 52 in the reaction chamber C and prevent the cells 52 from being broken due to a temperature difference. Leakage of air into the reaction chamber C can be prevented. Further, since the fuel gas chamber partition plate 55 is formed of a ceramic plate and the gap between the ceramic plate and the inner wall surface of the reaction container 51 is filled with the fibrous ceramics 82, the interior of the reaction container 51 can be reliably partitioned, which is unnecessary. The leakage of gas can be prevented, and since the fuel gas chamber partition plate 55 and the inner wall surface of the reaction vessel 51 are not joined to each other, even if the coefficient of thermal expansion is slightly different, each member is almost free from stress. It does not work and can prevent damage to cells and the like.

Further, the fibrous ceramics 82 is replaced with Al
_{Since 2} O ₃ is the main component and the content of SiO ₂ is 40% by weight or less, it is possible to prevent the SiO ₂ component from adhering to the air electrode or the fuel electrode of the cell and improve the power generation characteristics.

In FIG. 6, the combustion chamber partition plate 63 is composed of a pair of ceramic plates 79 and 80, and a conventional heat insulating board 84 in which alumina fibers are hardened with a binder is arranged between the ceramic plates 79 and 80. The fibrous ceramics 82 is filled in the outer peripheral portion of the solid oxide fuel cell unit 52 between the ceramics plates 79 and 80. The fibrous ceramics 82 is also provided between the inner surfaces of the cell insertion holes of the ceramic plates 79 and 80 and the outer surfaces of the cells.
Is filled.

Even with such a structure, the ceramic plate 7
The gas leakage can be prevented by the 9, 80, the fibrous ceramics 82, and the heat insulating board 84.

[0033]

Example A solid oxide fuel cell as shown in FIG. 1 was produced. First, a fuel gas partition plate 55 made of a ceramics plate containing Al ₂ O ₃ as a main component is housed in the reaction vessel 51, and Al ₂ O is placed in the gap between the fuel gas partition plate 55 and the inner wall surface of the reaction vessel 51. ₃ as the main component, 5% by weight of SiO ₂
The contained fibrous ceramics, trade name: Kaowool (manufactured by Isolite Industrial Co., Ltd.) was packed. And the reaction vessel 5
White smoke was introduced into No. 1, and it was visually confirmed that there was no gas flow from other than the fuel gas supply holes.

Next, on the fuel gas chamber partition plate 55, four stacks 77 each having nine cells 52 connected as shown in FIG. 4 are connected.
A set was made.

A combustion chamber partition plate 63 having the structure shown in (c) is housed in the reaction vessel 51, and the gap between the combustion chamber partition plate 63 and the outer surface of the solid oxide fuel cell unit 52, the combustion chamber partition plate 63.
The fibrous ceramics 82 described above was packed in the space between the inner wall surface of the reaction vessel 51 and the ceramics plates 79 and 80. After that, a jig was inserted into the fuel gas ejection holes formed in the ceramic plates 79 and 80 to complete the fuel gas ejection holes.

Next, the air chamber partition plate 61 made of the above-described heat insulating board is housed in the reaction vessel 51, and the air chamber partition plate 6 is placed.
The fibrous ceramics 82 was packed in the gap between the inner wall surface of the reaction vessel 51 and the inner wall of the reaction vessel 51. Then, white smoke was introduced into the reaction vessel 51, and it was visually confirmed that there was no air flow except through the air introduction tube 59.

Then, air and hydrogen gas were supplied as fuel gas into the reaction vessel 51, and power was generated at 1000 ° C. Further, it was confirmed whether or not gas leaked from other than the fuel gas ejection holes of the combustion chamber partition plate 63 by a temperature change by a thermocouple.

On the other hand, as shown in FIG. 7, the combustion chamber partition plate 6
3 is a heat insulating board 84 made of conventional alumina fiber
In the case of manufacturing in, as shown in FIG. 6, the combustion chamber partition plate 6
3 is composed of a pair of ceramic plates containing alumina as a main component, and a heat insulating board made of alumina fibers is arranged between them, and Al ₂ is provided between the combustion chamber partition plate 63 and the cell insertion hole of the heat insulating board. The case where the fibrous ceramics 82 made of O ₃ was packed was also confirmed. The results are shown in Table 1.

[0039]

[Table 1]

From Table 1, it can be seen that when the combustion chamber partition plate 63 is manufactured by the conventional heat insulating board 84, fuel gas leaks and the power generation performance is poor. On the other hand, in the case of the present invention in which the combustion chamber partition plate 63 is formed of a ceramic plate and the fibrous ceramics 82 made of Al ₂ O ₃ is packed, it is understood that the power generation performance is good.

Example 2 A solid oxide fuel cell similar to No. 2 of Example 1 was prepared and the performance after 1000 hours was compared by changing the amount of SiO ₂ in the fibrous ceramics 82. The results are shown in Table 2.

[0042]

[Table 2]

From Table 2, it can be seen that the power generation performance is best when the SiO ₂ content is 0, and the power generation performance deteriorates as the SiO ₂ content increases.

[0044]

According to the solid oxide fuel cell of the present invention, the inside of the reaction vessel can be reliably partitioned into the combustion chamber and the reaction chamber, unnecessary gas can be prevented from leaking, and the combustion chamber partition plate can be prevented. Since there is no joint between the cell and the cell or the inner wall surface of the reaction vessel, even if the coefficient of thermal expansion is slightly different, almost no stress acts on each member, and damage to the cell etc. can be prevented. it can. Moreover, since the combustion chamber partition plate has a two-layer structure, it is possible to suppress the transfer of heat in the combustion chamber to the cells in the reaction chamber, and prevent the cells from being broken due to a temperature difference.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a solid oxide fuel cell.

FIG. 2 shows a combustion chamber partition plate and its vicinity,
(A) is a side view, (b) is a plan view, and (c) is a sectional view.

FIG. 3 is a cross-sectional view of a solid oxide fuel cell mole.

FIG. 4 is a plan view showing a stack.

FIG. 5 is an explanatory diagram for explaining a gas flow in a solid oxide fuel cell unit.

FIG. 6 is a cross-sectional view of a combustion chamber partition plate composed of a pair of ceramic plates, a heat insulating board, and fibrous ceramics.

FIG. 7 is a cross-sectional view of a conventional solid oxide fuel cell in which a combustion chamber partition plate is composed of a heat insulating board.

[Explanation of symbols]

51 ... Reaction container 52 ... Solid oxide fuel cell 55 ... Fuel gas chamber partition plate 61 ... Air chamber partition plate 63 ... Combustion chamber partition plate 79, 80 ... Ceramic plate 82 ... Fibrous ceramics

Claims (2)

(57) [Claims] 1. A combustion chamber partition plate is used in a reaction container to form a combustion chamber and a reaction chamber, and a plurality of bottomed cylindrical solid oxide fuel cell units are formed in the combustion chamber partition plate. Each of them is inserted into a cell insertion hole and fixed, and air is supplied into each of the solid oxide fuel cells, and a fuel gas is supplied between the solid oxide fuel cells in the reaction chamber to cause a reaction. An excess fuel gas is ejected into the combustion chamber from a fuel gas ejection hole formed in the combustion chamber partition plate, and the solid electrolyte fuel cell is ejected into the combustion chamber.
A solid oxide fuel cell for reacting with the air discharged to burn the air, wherein the combustion chamber partition plates are formed of a pair of ceramic plates facing each other at a predetermined interval,
While filling the outer periphery of the solid oxide fuel cell unit between the ceramic plates with fibrous ceramics,
A solid oxide fuel cell, characterized in that a fibrous ceramic is filled in a gap between the outer peripheral surface of the combustion chamber partition plate and the inner wall surface of the reaction vessel. 2. The solid oxide fuel cell according to claim 1, wherein the fibrous ceramics contains Al ₂ O ₃ as a main component and the content of SiO ₂ is 40% by weight or less.