JP3545958B2 - Solid oxide fuel cell - Google Patents

Description

[0001]
TECHNICAL 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 and a reaction chamber are formed using a combustion chamber partition plate.
[0002]
[Prior art]
As shown in FIG. 6, the conventional solid oxide fuel cell uses an air chamber A, a combustion chamber B and a fuel chamber partition plate 57 in a reaction vessel 51 using an air chamber partition plate 53, a combustion chamber partition plate 55, and a fuel gas chamber partition plate 57. , A reaction chamber C and a fuel gas chamber D are formed.
[0003]
The plurality of bottomed cylindrical solid oxide fuel cells 59 housed in the reaction vessel 51 are respectively inserted and fixed in a plurality of cell insertion holes 60 formed in the combustion chamber partition plate 55, and the opening 61 thereof is used for combustion. One end of an air introduction pipe 63 fixed to the air chamber partition plate 53 is inserted into the combustion chamber B, protruding from the chamber partition plate 55.
[0004]
An excess fuel gas ejection hole 64 for introducing excess fuel gas into the combustion chamber B is formed in the combustion chamber partition plate 55, and the fuel gas is introduced into the reaction chamber C in the fuel gas chamber partition plate 57. A supply hole for supplying is formed.
[0005]
Further, the reaction vessel 51 has a fuel gas inlet 65 for introducing a fuel gas composed of, for example, hydrogen, an air inlet 67 for introducing air, and an exhaust port 69 for discharging gas burned in the combustion chamber B. Have been.
[0006]
In the solid oxide fuel cell 59, a solid electrolyte layer is formed on the surface of a cylindrical porous air electrode, a fuel electrode layer is formed on the surface of the solid electrolyte layer, and a current collector layer is formed on the air electrode layer. And a solid electrolyte layer.
[0007]
Such a solid oxide fuel cell supplies air from the air chamber A to the solid oxide fuel cell 59 via the air introduction pipe 63, and supplies a plurality of fuel gases from the fuel gas chamber D. Is supplied between the solid oxide fuel cells 59 and reacted in the reaction chamber C, and excess air and excess fuel gas are burned in the combustion chamber B, and the burned gas is discharged to the outside through the exhaust port 69. You.
[0008]
In the reaction in the reaction chamber C, the air supplied into the solid oxide fuel cell 59 diffuses the porous air electrode layer toward the solid electrolyte layer, and the fuel gas flows outside the solid oxide fuel cell 59. From the solid electrolyte layer, and is generated in the solid electrolyte.
[0009]
[Problems to be solved by the invention]
However, in the conventional solid oxide fuel cell, the outside diameter of the air introduction pipe 63 inserted into the solid oxide fuel cell 59 is as small as 50% to 60% of the inside diameter of the cell 59. The air does not diffuse sufficiently in the electrode layer, air cannot be efficiently supplied to the interface between the air electrode layer and the solid electrolyte layer, and most of the air contributes to the power generation reaction in the space between the air introduction pipe 63 and the cell 59. He was passing without any.
[0010]
For this reason, supply of oxygen in the air required for the power generation reaction may be insufficient at the power generation reaction interface between the air electrode layer and the solid electrolyte layer, thereby increasing polarization resistance and significantly deteriorating power generation performance. was there.
[0011]
An object of the present invention is to provide a solid oxide fuel cell capable of efficiently supplying air to an interface between an air electrode layer and a solid electrolyte layer.
[0012]
[Means for Solving the Problems]
As a result of studying the above problem, the present inventor has found that the air flow resistance between the air introduction pipe for supplying air into the solid oxide fuel cell and the cell is small, that is, air contributes to the reaction. The present inventors have found that by reducing the space through which the air passes, the air can be efficiently diffused into the air electrode layer and oxygen can be sufficiently supplied to the reaction interface between the air electrode layer and the solid electrolyte layer, leading to the present invention. It is.
[0013]
That is, the solid oxide fuel cell of the present invention comprises a combustion chamber and a reaction chamber formed in a reaction vessel using a combustion chamber partition plate, and a plurality of bottomed cylindrical solid oxide fuel cells are formed in the combustion chamber. A plurality of cell insertion holes formed in the partition plate are inserted and fixed so that the openings protrude from the combustion chamber partition plate to the combustion chamber side, and the air introduction pipe is inserted into the solid oxide fuel cell unit. And air is supplied into the solid oxide fuel cells by the air introduction pipe, and fuel gas is supplied between the solid oxide fuel cells in the reaction chamber to cause a reaction. In a solid oxide fuel cell, the outside diameter of the air introduction pipe is 80% or more of the inside diameter of the solid oxide fuel cell.
[0014]
Here, it is desirable that the thickness of the air introduction pipe is 1 mm or less.
[0015]
[Action]
In the solid oxide fuel cell according to the present invention, the outer diameter of the air inlet pipe is set to 80% or more of the inner diameter of the solid oxide fuel cell, so that the air inlet pipe for supplying air and the solid oxide fuel cell are separated. However, the air flow resistance can be increased, that is, the space through which the air passes without contributing to the reaction can be reduced, and the air can be efficiently diffused into the porous air electrode layer having a relatively high resistance. Sufficient oxygen can be supplied to the power generation reaction interface between the air electrode layer and the air electrode layer, the concentration overvoltage caused by the oxygen supply rate-limiting, that is, the polarization resistance is reduced, efficient power generation can be performed, and the power generation performance can be improved. .
[0016]
In addition, by making the thickness of the air introduction pipe 1 mm or less, efficient heat transfer is possible, and the inside diameter of the air introduction pipe is increased, so that the flow velocity in the pipe is reduced, and the preheating of the air flowing in the pipe is sufficiently performed. become able to. For this reason, the power generation performance can be further improved.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
As shown in FIG. 1, the solid oxide fuel cell of the present invention comprises an air chamber A, a combustion chamber partition plate 7, a combustion chamber partition plate 5, and a fuel gas chamber partition plate 7 in a reaction vessel 1. B, a reaction chamber C, and a fuel gas chamber D are formed.
[0018]
The plurality of bottomed cylindrical solid oxide fuel cells 9 housed in the reaction vessel 1 are inserted and fixed in a plurality of cell insertion holes 6 formed in the combustion chamber partition plate 5, respectively. One end of an air introduction pipe 11 inserted into and fixed to the air chamber partition plate 3 is inserted into the combustion chamber B from the combustion chamber partition plate 5.
[0019]
As shown in FIG. 2, the combustion chamber partition plate 5 is formed with a large number of surplus fuel gas ejection holes 12 for introducing surplus fuel gas into the combustion chamber B. As shown in FIG. A large number of supply holes 14 for supplying fuel gas into the reaction chamber C are formed in the fuel gas chamber partition plate 7.
[0020]
Further, the reaction vessel 1 has a fuel gas inlet 13 for introducing a fuel gas composed of, for example, hydrogen, an air inlet 17 for introducing air, and an exhaust port 19 for discharging gas burned in the combustion chamber B. Have been.
[0021]
As shown in FIG. 3, the cell 9 includes, for example, a LaMnO ₃ -based air electrode layer 25 as a support tube, and a solid electrolyte layer made of Y ₂ O ₃ stabilized ZrO ₂ formed on the surface of the air electrode layer 25. 26, a fuel electrode layer 27 of Ni- zirconia formed on the surface of the solid electrolyte layer 26, and an interconnector 28. consisting LaCrO ₃ system connected air electrode layer to 25 electrically.
[0022]
Then, as shown in FIG. 4, the interconnector 28 of one cell 9 is connected to the fuel electrode layer 27 of the other cell 9 via a connecting member 31 such as Ni metal fiber or the like. And a plurality of cells 9 are electrically connected to each other to form a stack 33. Such a stack 33 is housed in the reaction vessel 1 as shown in FIG. A fuel cell is configured. In the reaction vessel 1, an electrode 35 connected to the interconnector 28 of one cell 9 and an electrode 37 connected to the fuel electrode layer 27 of the other cell 9 are arranged. Power is extracted via
[0023]
In such a solid oxide fuel cell, air is introduced from the air inlet 17 into the cell 9 through the air inlet pipe 11, and hydrogen is introduced from the fuel gas inlet 13, and the fuel gas chamber partition plate 7 This is performed by dispersing the gas in the dispersion holes and introducing the gas to the outside of the cell 9. The surplus air and fuel gas are burned in the combustion chamber B and discharged to the outside from the exhaust port 19.
[0024]
FIG. 5 shows a gas flow of one solid oxide fuel cell unit. Hydrogen gas (fuel gas) is introduced from below the cell and proceeds upward while being oxidized by power generation. On the other hand, air (oxidizing gas) is introduced from above the cell to below the cell via the air introduction pipe 11. Then, it flows upward from the lower part inside the cell. The air discharged from the upper part of the cell reacts with the hydrogen gas not consumed by the power generation and burns in the combustion chamber B.
[0025]
Then, in the solid oxide fuel cell of the present invention, as shown in FIG. 2 (c), the outer diameter R ₁ of the air inlet tube 11 is a more than 80% of the inner diameter R ₂ of the cell 9. Here, it is desirable that the thickness t of the air introduction pipe 11 be 1 mm or less in order to sufficiently heat the air flowing through the air introduction pipe 11.
[0026]
The solid oxide fuel cell configured as described above, the outer diameter R ₁ of the air inlet tube 11, since 80% or more of the inner diameter R ₂ of the cell 9, the air inlet tube 11 for supplying air and the cell 9 The air flow resistance can be increased, that is, the space through which the air passes without contributing to the reaction can be reduced, and the air can be efficiently diffused into the porous air electrode layer 25 having a relatively high resistance, and Sufficient oxygen can be supplied to the power generation reaction interface between the electrolyte layer 26 and the air electrode layer 25, and the concentration overvoltage caused by the oxygen supply rate-limiting, that is, the polarization resistance is reduced, thereby enabling efficient power generation and improving power generation performance. can do.
[0027]
Further, by setting the thickness t of the air introduction pipe 11 to 1 mm or less, efficient heat transfer can be performed, and the inner diameter of the air introduction pipe 11 increases, so that the flow velocity in the pipe decreases, and Preheating can be sufficiently performed, and such preheated air can be introduced into the cell 9, so that the power generation performance can be further improved.
[0028]
【Example】
La _0.9 Sr _0.1 MnO ₃ having a purity of 99.9% and an average particle size of 5 μm as an air electrode material, and 10 mol% of an purity of 99.9% and an average particle size of 0.7 μm as a solid electrolyte material ZrO ₂ containing Y ₂ O ₃ was used as an interconnector material, La _0.8 Ca _0.22 CrO ₃ powder having a purity of 99.9% and an average particle diameter of 1 μm, and 80 wt% Ni or Ru as a fuel electrode material. the ZrO ₂ containing the prepared.
[0029]
After sintering La _0.9 Sr _0.1 MnO ₃ powder by extrusion molding, a hollow cylindrical air electrode molded body having an outer diameter of 18 mm, a thickness of 2.3 mm, and a length of 300 mm is produced. did. Thereafter, using a ZrO ₂ powder containing 10 mol% Y ₂ O ₃ and La _0.8 Ca _0.22 CrO ₃ powder, a solid electrolyte sheet and an interconnector sheet having a thickness of 150 μm were produced by a doctor blade method. Thereafter, each sheet was wound around the above air electrode molded body and fired at 1500 ° C. for 3 hours.
[0030]
Further, a slurry made of ZrO ₂ powder containing 80% by weight of NiO or Ru was applied to the surface of the solid electrolyte layer and baked at 1400 ° C. for 2 hours to obtain a solid oxide fuel cell as shown in FIG. Produced. The thickness of the solid electrolyte layer was 100 μm.
[0031]
Sixteen cylindrical solid oxide fuel cells were connected in four-by-four parallel to form a stack, and this stack was placed in a reaction vessel as shown in FIG. In addition, the projecting height of the cell from the combustion chamber partition plate was 15 mm. Then, a solid oxide fuel cell according to the present invention in which the outer diameter of the air inlet tube was 80% and 90% of the inner diameter of the cell, and a conventional solid oxide fuel cell in which the outer diameter was 60% were produced. Here, the thickness of all the air introduction pipes was 1 mm.
[0032]
Then, 40 SLM of air was flown into the air electrode, and 6.3 SLM of hydrogen gas was flowed to the fuel electrode side, and power was generated at a temperature setting of the power generating furnace of 1000 ° C. In this power generation test, when the output density was measured, it was 0.1 W / cm ² in the conventional solid oxide fuel cell, and in the solid oxide fuel cell of the present invention, the outer diameter of the air introduction tube and the inner diameter of the cell were measured. ratio 0.13 W / cm ² at those 80%, the ratio was 0.14 W / cm ² at of 90%. This indicates that the polarization resistance was effectively reduced.
[0033]
【The invention's effect】
In the solid oxide fuel cell of the present invention, the flow resistance of air between the air supply pipe for supplying air and the solid oxide fuel cell can be increased, that is, the space where air does not pass through without contributing to the reaction is reduced. Air can be efficiently diffused into the porous air electrode layer with relatively high resistance, and sufficient oxygen can be supplied to the power generation reaction interface between the solid electrolyte layer and the air electrode layer. The concentration overvoltage, that is, the polarization resistance, is reduced, efficient power generation can be performed, and power generation performance can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic view of a solid oxide fuel cell according to the present invention.
FIGS. 2A and 2B show a combustion chamber partition plate and the vicinity thereof, wherein FIG. 2A is a side view, FIG. 2B is a plan view, and FIG. 2C is a plan view showing a relationship between a cell and an air introduction pipe.
FIG. 3 is a sectional view of a solid oxide fuel cell.
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.
FIG. 6 is a schematic view of a conventional solid oxide fuel cell.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Reaction container 5 ... Combustion chamber partition plate 6 ... Cell insertion hole 9 ... Solid oxide fuel cell 10 ... Opening 11 ... Air introduction pipe B ... Combustion chamber C: Reaction chamber

Claims (1)

A combustion chamber and a reaction chamber are formed using a combustion chamber partition plate in the reaction vessel, and a plurality of bottomed cylindrical solid oxide fuel cells are inserted into a plurality of cell insertion holes formed in the combustion chamber partition plate. An opening is inserted and fixed so that the opening protrudes from the combustion chamber partition plate toward the combustion chamber, and an air introduction pipe is inserted into the solid oxide fuel cell, respectively, so that the air is introduced into the air. A solid oxide fuel cell which supplies the gas into the solid oxide fuel cells by a pipe, and supplies and reacts a fuel gas between the solid oxide fuel cells in the reaction chamber, wherein the air introduction; A solid oxide fuel cell, wherein an outer diameter of the tube is 80% or more of an inner diameter of the solid oxide fuel cell.

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