JPH06275305A - Fuel cell - Google Patents

Abstract

PURPOSE:To provide a fuel cell having a long lifetime where deterioration of cell constituting members can be restrained by setting cell surface inner temperatures in cells to an approximately uniform value. CONSTITUTION:A plurality of cells 4 where a fuel electrode 2 and an oxidant electrode 3 hold an electrolyte 1 therebetween are laminated, thus obtaining a fuel cell. In this fuel cell, the passing directions of fuel gas and/or oxidant gas at the surfaces of the fuel electrodes 2 and/or at the surfaces of the oxidant electrodes 3 are alternately opposite in the cells.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, and more particularly to improvement of a method for supplying a fuel gas and an oxidant gas to a fuel electrode and an oxidant electrode.

[0002]

2. Description of the Related Art A fuel cell is a device for obtaining electric energy from hydrogen obtained by reforming a fuel such as natural gas, methanol and coal gas, and oxygen in the air, and can obtain high power generation efficiency. . Therefore, it is attracting attention as a promising new power generation system that can be used in various applications from space use to automobile use, large-scale power generation to small-scale power generation. Such a fuel cell has a phosphoric acid fuel cell (PA) depending on the type of electrolyte used.
FC), molten carbonate fuelcell;
MCFC), solid electrolyte fuel cell (solid oxide fuel cell;
SOFC, Alkaline fuel cell (AF)
C) etc.

Generally, a fuel cell has a structure in which a plurality of cells, each having a fuel electrode and an oxidant electrode arranged through an electrolyte, are stacked, and a gas separation plate is interposed between the cells. in this case,
As the gas separation plate, for example, a gas separation plate 30 having a structure as shown in FIG. 4 is used, an anode gas flow channel 31 is provided on one surface, and a cathode gas flow channel 32 is provided on the opposite surface. Is provided. In addition, as shown in FIG. 5, on each reaction gas supply / discharge surface of the battery stack 33, an anode gas supply manifold 34, an anode gas discharge manifold 35, a cathode gas supply manifold 36, and a cathode gas discharge manifold 37 are provided. Each is installed.

[0004]

By the way, when the fuel gas and the oxidant gas are supplied to the fuel electrode and the oxidant electrode to generate the power of the fuel cell, the temperature on the discharge side of each reaction gas is accompanied by the heat generation of the cell. Becomes higher. Here, in the case of the fuel cell having the above structure, the flow directions of the fuel gas and the oxidant gas in each fuel electrode surface and each oxidant electrode surface are the same, The temperature on the oxidant gas discharge side is usually about 50 ° C. to 80 ° C. higher than the operating temperature of the battery. As a result, the in-plane temperature of the battery in each cell becomes uneven,
There has been a problem that the deterioration rate of the battery constituent members such as the gas separation plate and the corrugate is increased and the battery characteristics are deteriorated.

The present invention has been made in view of the above problems, and provides a long-life fuel cell in which deterioration of battery constituent members is suppressed by making the in-plane temperature of the cells in each cell substantially uniform. With the goal.

[0006]

In order to solve the above-mentioned problems, the present invention provides a fuel cell having a structure in which a plurality of cells having a fuel electrode and an oxidant electrode arranged through an electrolyte are stacked, and in each fuel electrode plane And / or the flow direction of the fuel gas and / or the oxidant gas in each oxidant electrode surface is set to be opposite for each cell.

[0007]

As described above, if the flow direction of the fuel gas in each fuel electrode surface is reversed in each cell, the supply side and the discharge side of the fuel gas in each fuel electrode surface are in each cell. Alternate. Therefore, since the fuel gas supply side, which has a lower temperature than the discharge side, is located above and below the fuel gas discharge side, which has a high temperature, the high temperature on the fuel gas discharge side is moderated by the low temperature on the fuel gas supply side. Similarly, since the fuel gas discharge side, which has a higher temperature than the supply side, is located above and below the fuel gas supply side, which has a low temperature, the low temperature on the fuel gas supply side rises slightly due to the high temperature on the fuel gas discharge side. Therefore, the in-plane temperature of the cell at each fuel electrode becomes substantially uniform. Similarly, the in-plane temperature of the battery at each oxidant electrode becomes substantially uniform.

As a result, the in-plane temperature of the battery in each cell becomes substantially uniform, so that deterioration of the battery constituent members is suppressed and stable battery characteristics can be obtained for a long period of time.

[0009]

1 is a perspective view showing a part of a molten carbonate fuel cell according to an embodiment of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a perspective view of a gas separation plate. is there. In this molten carbonate fuel cell, as shown in FIG. 1, a plurality of cells 4 each having an anode 2 and a cathode 3 arranged with an electrolyte plate 1 sandwiched therebetween are stacked, and gas separation plates 5 and 11 are provided between the cells 4. As shown in FIG. 2, the anode gas supply manifold 7a.
8a, anode gas discharge manifolds 7b and 8b, cathode gas supply manifolds 9a and 10a, and cathode gas discharge manifolds 9b and 10b, respectively.

The cell 4 has an electrolyte plate 1 in which a eutectic salt of lithium carbonate and potassium carbonate is held in a porous ceramic material containing lithium aluminate as a main component,
Anode 2 made of an alloy of nickel and aluminum
And a cathode 3 mainly composed of a nickel oxide sintered body. The anode 2 of each cell 4 is connected to the cathode 3 of the adjacent cell 4 by the gas separation plates 5 and 11.
, And all the stacked cells 4 are electrically connected in series.

The gas separation plates 5 and 11 are interposed between the cells 4 of the battery stack 6 as shown in FIG. 1, and the gas separation plates 5 and the gas separation plates 11 are alternately interposed for each cell. ing. An anode gas flow path 12 is provided on the surface side of the gas separation plates 5 and 11 that contacts the anode 2, and a cathode gas flow path 13 that has substantially the same shape as the anode gas flow path 12 is provided on the surface side that contacts the cathode 3. It is provided.

Further, the anode gas supply ports 5a and 11a and the anode gas discharge port 5 provided in the gas separation plate 5/11 are provided.
b · 11b, and the cathode gas supply ports 5c · 11c and the cathode gas discharge ports 5d · 11d are provided at positions diagonal to each other. And the anode gas supply port 5
The a and 11a correspond to the anode gas supply manifolds 7a and 8a, respectively, as shown in FIG. Similarly, the anode gas discharge ports 5b and 11b respectively correspond to the anode gas discharge manifolds 7b and 8b, the cathode gas supply ports 5c and 11c respectively correspond to the cathode gas supply manifolds 9a and 10a, and the cathode gas discharge port 5
d and 11d are cathode gas exhaust manifolds 9b and 1
0b respectively.

As shown in FIG. 2, the reaction gas supply manifold and the reaction gas discharge manifold are mounted on the same surface of the reaction gas supply / discharge surfaces of the battery stack 6 so as to be bilaterally symmetrical. Specifically, as shown in FIG. 2, the anode gas supply manifold 7a and the anode gas discharge manifold 8b are mounted on the same surface of the reaction gas supply / discharge surface of the battery stack 6 so as to be symmetrical. There is. Similarly, the anode gas supply manifold 8a
And a manifold 7b for discharging an anode gas, a manifold 9a for supplying a cathode gas, a manifold 10b for discharging a cathode gas, and a manifold 10 for supplying a cathode gas.
The cathode gas discharge manifold 9a and the cathode gas discharge manifold 9b are attached symmetrically on the same surface of the reaction gas supply / discharge surface. Each of the manifolds 7 to 10 is made of a stainless material, and is attached to the reaction gas supply / discharge surface of the battery stack 6 via a ceramic insulating frame (not shown).

Next, the flow of the reaction gas in the molten carbonate fuel cell configured as described above will be specifically described with reference to FIG. In FIG. 3, the solid line shows the flow of the anode gas and the broken line shows the flow of the cathode gas. The anode gas and the cathode gas flow in each cell in a cross (cross) shape. First, the anode gas supplied to the anode gas supply manifold 7a is substantially evenly dispersed in the anode gas supply ports 5a of each gas separation plate 5, and then while flowing through the anode gas flow path 12 of each gas separation plate 5. An anode gas is supplied to each anode 2. After that, the high-temperature anode exhaust gas that has contributed to the cell reaction is discharged to the anode gas discharge manifold 7b via the anode gas discharge port 5b of each gas separation plate 5. Similarly, the anode gas supplied to the anode gas supply manifold 8 a is supplied to the anode gas supply port 11 of each gas separation plate 11.
After being substantially evenly dispersed in a, the anode gas is supplied to each anode 2 while flowing through the anode gas flow path 12 of each gas separation plate 11. After that, the high-temperature anode exhaust gas that has contributed to the cell reaction is discharged to the anode gas discharge manifold 8b via the anode gas discharge port 11b of each gas separation plate 11.

In this case, since the flowing direction of the anode gas in the surface of each anode 2 is the opposite direction for each cell, the supply side and the discharge side of the anode gas in each surface of the anode 2 are alternated for each cell. Become. Specifically, since the anode gas supply side 5a, which has a lower temperature than the discharge side 11b, is located above and below the anode gas discharge side 11b, which has a high temperature,
The high temperature on the anode gas discharge side 11b is moderated by the high temperature on the anode gas supply side 5a. Similarly, since the anode gas discharge side 5b having a temperature higher than that of the supply side 11a is located above and below the anode gas supply side 11a having a low temperature,
The low temperature on the anode gas supply side 11a rises slightly due to the high temperature on the anode gas discharge side 5b. Therefore, the in-plane temperature of the battery at each anode 2 becomes substantially uniform.

On the other hand, the cathode gas supply manifold 9
The cathode gas supplied to a is substantially evenly dispersed in the cathode gas supply port 5c of each gas separation plate 5, and then the cathode gas is supplied to each cathode 3 while flowing through the cathode gas flow path 13 of each gas separation plate 5. To supply. After that, the high-temperature cathode exhaust gas that has contributed to the cell reaction is discharged to the cathode gas discharge manifold 9b through the cathode gas discharge port 5d of each gas separation plate 5. Similarly, the cathode gas supplied to the cathode gas supply manifold 10a is
After being substantially evenly dispersed in the cathode gas supply ports 11c of each gas separation plate 11, the cathode gas is supplied to each cathode 3 while flowing through the cathode gas flow path 13 of each gas separation plate 11. After that, the high-temperature cathode exhaust gas that has contributed to the cell reaction is discharged to the cathode gas discharge manifold 8b via the cathode gas discharge port 11d of each gas separation plate 11.

In this case, since the flow direction of the cathode gas in each cathode 3 surface is the opposite direction for each cell, the supply side and the discharge side of the cathode gas in each cathode 3 surface alternate for each cell. Become. Specifically, since the cathode gas supply side 5c, which has a lower temperature than the discharge side 11d, is located above and below the cathode gas discharge side 11d that has a high temperature,
The high temperature on the cathode gas discharge side 11d is moderated by the high temperature on the cathode gas supply side 5c. Similarly, since the cathode gas discharge side 5d, which has a higher temperature than the supply side 11c, is located above and below the cathode gas supply side 11c, which has a low temperature,
The low temperature on the cathode gas supply side 11c rises slightly due to the high temperature on the cathode gas discharge side 5d. Therefore, the in-plane temperature of the battery at each cathode 3 becomes substantially uniform.

As a result, the in-plane temperature of the battery in each cell becomes substantially uniform, so that deterioration of the battery constituent members is suppressed and stable battery characteristics can be obtained for a long period of time. [Other Matters] Although a molten carbonate fuel cell was used in the above-mentioned embodiment, it is of course possible to apply it to a phosphoric acid fuel cell or the like.

[0019]

As described above, according to the present invention, the flow direction of the fuel gas in each fuel electrode surface is opposite for each cell, so that the supply side and the discharge side of the fuel gas in each fuel electrode surface are the same. Are alternated for each cell. Therefore, since the fuel gas supply side, which has a lower temperature than the discharge side, is located above and below the fuel gas discharge side, which has a high temperature, the high temperature on the fuel gas discharge side is moderated by the low temperature on the fuel gas supply side. Similarly, since the fuel gas discharge side, which has a higher temperature than the supply side, is located above and below the fuel gas supply side, which has a low temperature, the low temperature on the fuel gas supply side rises slightly due to the high temperature on the fuel gas discharge side. Therefore, the in-plane temperature of the cell at each fuel electrode becomes substantially uniform. Similarly, the in-plane temperature of the battery at each oxidant electrode becomes substantially uniform.

As a result, the in-plane temperature of the battery in each cell becomes substantially uniform, so that deterioration of the battery constituent members is suppressed and stable battery characteristics can be obtained for a long period of time.

[Brief description of drawings]

FIG. 1 is a perspective view showing a part of a molten carbonate fuel cell according to an embodiment of the present invention.

FIG. 2 is a plan view of a molten carbonate fuel cell according to an embodiment of the present invention.

FIG. 3 is a perspective view of a gas separating plate of a molten carbonate fuel cell according to an embodiment of the present invention.

FIG. 4 is a perspective view of a conventional gas separation plate.

FIG. 5 is a plan view of a conventional fuel cell.

[Explanation of symbols]

 1 Electrolyte 2 Fuel electrode 3 Oxidant electrode 4 Cell

Claims (1)

[Claims] 1. A fuel cell having a structure in which a plurality of cells in which a fuel electrode and an oxidant electrode are arranged through an electrolyte are stacked, and a fuel gas and / or in each fuel electrode surface and / or each oxidant electrode surface Alternatively, the fuel cell is characterized in that the flow direction of the oxidant gas is reversed in every cell.