JPH04106876A - Fuel cell device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a fuel cell device having a wet seal portion.

[Prior Art] FIG. 6 shows the appearance of a conventional molten carbonate fuel cell device. In the figure, (1) is a fuel cell stack, (2^)<
2B) are manifolds for supplying fuel gas and oxidant gas, respectively. Figure 7 shows the manifold (2^)
(2B) is a perspective view showing a state in which it is removed.

In the figure, (3) is the separator plate, and the fuel gas electrode (6
) is separated from the fuel gas flow path (4) provided opposite to the oxidizing gas electrode (7). Agent gas flow path (
5) are corrugated channel plates (4a) and (5a), respectively.
is formed by. The fuel gas electrode (6) and the oxidant gas electrode (7) are arranged with the electrolyte matrix (8) sandwiched therebetween, and constitute a single cell (1a).

The fuel gas electrode (6) is made of, for example, a porous material such as Niragel, and the oxidant gas electrode (7) is made of, for example, a NiO porous material. (14) is a reforming catalyst filled in the fuel gas flow path (4), and (9) is a current collector plate that holds the oxidant gas electrode (7) and allows the generated current to pass therethrough. (12
) and (13) are a fuel side wet seal part and an oxidizer side wet seal part, respectively, which are provided on the separator plate (3) and separate and seal the inside and outside of the battery. A molten carbonate fuel cell is a laminate formed by alternately stacking unit cells (1a) and separator plates (3), and end plates (10) and <11) are provided at the upper and lower ends. It is being

Next, the operation of this type of molten carbonate fuel cell will be explained. When a fuel gas such as a hydrocarbon and water vapor are supplied to the fuel gas flow path (4), the hydrocarbon reacts with the water vapor through a reforming reaction on the reforming catalyst (14) to form hydrogen, -carbon oxide, and converted to carbon dioxide gas. When the hydrocarbon is methane, this reaction is represented by the following equation.

CH, +H20--CO2+H2(1)CO2H20-
CO2 + H2 (2) The generated hydrogen diffuses through the pores of the porous fuel gas electrode (6) and combines with the carbonate ions that have migrated from the oxidant gas electrode () via the electrolyte matrix (8) as shown below. Subjected to anode reaction.

H2+ COs--→H20+cO2+2e- (3) On the other hand, a mixed gas of air and carbon dioxide is supplied to the oxidant gas flow path (5), and carbon dioxide and oxygen are fed to the porous oxidant gas electrode (7). The pores are diffused and subjected to the cathode reaction shown below.

C○2+ 1 /202+ 2 e −→COz”−(
4) The anodic reaction and cathodic reaction are collectively referred to as the battery reaction.The alkali carbonate impregnated into the electrolyte matrix (8) and in a molten state at around the operating temperature of 650°C plays the role of conducting carbonate ions. take charge

In this way, a fuel cell is a fuel cell that uses fuel gas such as hydrocarbons supplied from the fuel gas supply manifold (2^) and oxidant gas such as air supplied from the oxidant gas supply manifold (2B). A device that converts chemical energy directly into electrical energy through an electrochemical reaction to obtain electricity.

[Problem M to be solved by the invention] The wet seal parts (12) and (13) of the conventional molten carbonate fuel cell configured as described above are formed of flat metal plates and are not flexible. Therefore, the electrode (6),
If the thickness of (7) is inappropriately designed, or if the electrodes (6) and (7) shrink as the battery operates, the wet seal parts (12) and (13) will not deform and the electrolyte There was a problem in that the matrix (8), electrodes (8), (7), etc. caused poor contact and the internal resistance of the battery increased.

FIG. 8 shows a partial perspective view of a molten carbonate fuel cell proposed in, for example, Japanese Unexamined Patent Publication No. 60-220571, which solves these problems. As shown in the figure, a spacer (15) having the same strength and flexibility as the electrode part is arranged inside the wet seal part (12), and the thickness of the wet seal part (12) is equal to that of the electrode (6) flow path. Board (4a
), it follows the deformation and shrinkage of the electrode part, maintains good contact between the electrode (6) and the electrolyte matrix (8), and suppresses an increase in internal resistance.

Furthermore, as shown in FIG. 9, Japanese Patent Application Laid-Open No. 62-188177 discloses that a cap (16) is attached to the manifold facing part (12a) for sealing and flattening the distal end of the manifold. Improved sealing performance.

However, with such a structure of the wet seal part (12), especially when a load is applied, the volume of gas expands at the electrode part due to the anode reaction and the flow resistance increases, so that the gas is not supplied from the manifold (2). A part of the gas flows into the inside of the wet seal part (12i), and the amount of gas supplied to the electrode part decreases by that amount, increasing the net fuel gas utilization rate and deteriorating the battery characteristics. A new problem arises.

Furthermore, in the internal reforming fuel cell shown in FIG. 10, since the fuel gas flow path (4) of the electrode part is filled with the reforming catalyst (14), the flow path resistance increases due to the catalyst filling and the reforming reaction This problem becomes most noticeable when the gas flow rate increases.

The present invention was made in order to solve the problems of the conventional device as described above, and it maintains contact between the electrode and electrolyte matrix, does not increase internal resistance even when the electrode shrinks, and has fuel inside the wet seal part. The object of the present invention is to obtain a fuel cell device with high cell characteristics that prevents gas from going around.

[Means for Solving the Problems] A fuel cell device according to the present invention includes a fuel gas electrode and an oxidizing gas electrode disposed on one side and the other side of an electrolyte matrix, respectively, and an oxidant gas electrode disposed on the outside of these electrodes. a plurality of unit cells having a fuel gas flow path and an oxidant gas flow path provided therein and stacked with a separator interposed therebetween; a wet seal portion provided on both sides of the separator in a gas flow direction; The wet seal portion is configured to include gas shielding means for preventing gas from flowing inside the wet seal portion.

[Function] The gas shielding means in the present invention closes the inner space of the wet seal portion and suppresses gas from entering the wet seal portion.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, (12) is a wet seal part formed integrally with the separator (3), and (17> is a gas shielding means for preventing fuel gas from going around to the inside of the wet seal part (12). In this example, the gas shielding means (1
7) includes a shielding plate (18) with an opening-shaped cross section provided inside the wet seal portion (12), and spacer members (19) (20) provided inside this shielding plate (18);
It is comprised of a cap (16) that closes the manifold opposing part (12a) side, that is, the front end of the paper in FIG. Note that the wet seal portion (12) and the gas shielding means (17) are also provided at the right end of the separator plate (3) along the direction of the gas flow path (4). Illustration is omitted.

The separator plate (3) has a thickness of, for example, 0.1 to 1. O
nickel and stainless steel (e.g. 5tlS316L,
or 5tlS31OS>, and the nickel thickness ratio is about 179 to 176, taking into consideration corrosion resistance. As shown in the prior art shown in FIG.
b) (12b) is folded back to the fuel gas electrode side, and the two sides are parallel to the oxidizing gas flow path <13b) (13b)
are folded back to the oxidizing gas electrode side, and these folded pieces form the wet seal parts (on the fuel gas side and oxidizing gas side).
12) and (13) are formed. For corrosion resistance, the nickel side is configured to face the fuel gas flow path (4). Furthermore, a cap (16) is joined to the manifold facing part (12a) of a part of the corner formed by folding back, using plasma arc welding or the like to seal the tip and flatten the manifold facing part (12a). hand,
Maintains gas sealing properties. The shielding plate (18) is made by bending a nickel plate with a thickness of 0.1 to 0.5 mm into a U-shape as shown in FIG. Insert it inside the wet seal part (12). In order to hold the wet seal part (12), smooth members (19) and (20) having the same strength and flexibility as the electrode part are built into the U-shaped inner part.

In the molten carbonate fuel cell configured as described above, even if the gas volume expands at the electrode part and the flow resistance increases, or the gas flow resistance increases due to the reforming catalyst and the gas due to the reforming reaction. Even if the flow rate increases, the provision of gas shielding means in the wet seal section (12) prevents the fuel gas from entering the wet seal section, and prevents the fuel gas from entering the wet seal section.
), (7) and the electrolyte matrix (8), and can prevent deterioration of battery characteristics. In particular, this effect is most prominently exhibited in internal reforming fuel cells in which the fuel gas flow path is filled with a reforming catalyst.

Note that the spacer member (19) is not limited to a corrugate shape or a spring shape.

FIG. 2 is a perspective view showing another embodiment of the present invention. In FIG. 6, (21m), (21b), and (21e) are gas shielding materials made of porous bodies having different porosity. A porous body with low porosity is placed on the side near the electrode where gas sealing performance is required.

The aforementioned multi-pore shielding material (21) is required to have appropriate porosity and bore diameter to shield gas while maintaining flexibility. Examples of materials that can be preferably used include porous metals containing Ni and C, such as foamed metal sheets (for example, manufactured by Sumitomo Metal Industries, Ltd., trade name: Celmet), and metal fibers such as Ni, Cr, Ni, and stainless steel. The porosity of the porous body can be easily reduced by press-forming it under a predetermined pressure. In addition, flexibility can be increased by increasing the porosity.

Even in other embodiments configured as described above, the same effects as those in FIG. 1 can be expected.

In addition, as shown in FIG. 3, in the pores of the porous body (21),
It may also be impregnated with a sealing material (22) that melts or solidifies at the operating temperature and blocks the flow of gas.

Even in this case, the sealing effect will be greater if more of the sealing material (22) soaks into the side of the porous body that is desired to be sealed. Preferably used sealing materials (22) include, for example, eutectic salts of lithium carbonate and potassium carbonate, which are the same as the electrolyte components. In addition, coagulable sealing material (2
As 2), base material such as zirconia, which is used as a sealing material for manifolds, may be infiltrated into the porous body and filled.

In addition, although a plurality of porous bodies having different porosity were used in the above embodiment, only one porous body may be used.

It is also possible to use one porous body whose porosity is partially changed.

FIG. 4 is a perspective view showing the main parts of still another embodiment.

Both ends (the figure shows one end) of the separator plate (3) are sealed in the shape of a pile, a wet seal part (12) is formed on the upper surface of the pile-shaped part (23), and the pile-shaped part The same effect can be obtained even if the gas shielding means is configured by the side surface portion (23). The details of this embodiment will be explained below.

Fold both ends of the cladding plate four times as shown in the figure, and join the folded part (^) and the surface (B part) where the cladding plate (3) touches by welding.
A cap similar to the cap (16) shown in the figure is joined (not shown). Before joining, a spacer (not shown) that holds the wet seal part (12) is inserted inside. It is desirable that this spacer has the same strength and flexibility as the electrode part. Corrugated plate used as plate (4a), porous body (21) shown in Fig. 2
etc. can be used. Furthermore, if the thickness of the separator plate (3) is selected to have appropriate strength and flexibility, the spacer can be omitted. In this way, the inside of the wet seal (12) is completely sealed, and it is possible to prevent fuel gas from going around.

FIG. 5 shows an embodiment that is a further improvement of the embodiment shown in FIG. This member (23) is joined with, for example, a 2-inch solder (24). In brazing, the entire separator plate (3) is heated to a temperature higher than the melting point of the brazing material (24), and the joining member (23) is pressurized through the brazing material (24), so unlike welding, it is not possible to locally It has advantages such as less temperature difference and residual stress, and less deformation of the member. Furthermore, a pile-shaped member (23) having a wet seal portion (12)
Since the parts are manufactured separately, there is the advantage that folding the parts can be easily delayed, and the manufacturing process can be shortened.

Incidentally, in each of the above embodiments, the case where the present invention is applied to a molten carbonate fuel cell has been described, but the present invention is not limited to this.

[Effects of the Invention] As described above, according to the present invention, since the structure is provided with a gas shielding means for preventing gas from flowing inside the wet sill portion, fuel gas is prevented from flowing inside the wet sill portion. This has the effect of preventing detouring and providing a fuel cell device with excellent battery characteristics.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a partially cutaway perspective view showing the fuel gas inflow side of a wet seal section, which is a main part of a molten carbonate fuel cell according to an embodiment of the present invention, and FIG. FIG. 3 is a perspective view showing a main part of another embodiment of the invention, and FIG. 3 is a perspective view showing an embodiment in which the porous body in the embodiment shown in FIG. 2 is impregnated with a sealing material. FIG. 4 is a perspective view showing a main part of still another embodiment of the present invention, and FIG. 5 is a perspective view showing an embodiment that is a further improvement of the embodiment shown in FIG. Figure 6 is a perspective view showing a general molten carbonate fuel cell with a manifold attached, Figure 7 is a perspective view of a general internal reforming fuel cell, and Figure 8 is a conventional molten carbonate fuel cell. FIG. 9 is a perspective view showing the separator plate of another conventional molten carbonate fuel cell, and FIG. 10 is a partial perspective view showing the main parts of a salt fuel cell. FIG. In the figure, (3) is a separator plate, (4) is a fuel gas flow path, (6) is a fuel gas electrode, (8) is an electrolyte matrix, (12) is a wet seal part, and (17) is a gas shielding means. be. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] An electrolyte matrix, a fuel gas electrode and an oxidant gas electrode disposed on one side and the other side of the electrolyte matrix, and a fuel gas flow path and an oxidant gas flow disposed on the outside of these electrodes, respectively. a plurality of unit cells stacked with a separator plate in between, a wet seal portion provided on both sides of the separator plate in the gas flow direction, and gas flowing inside the wet seal portion; A fuel cell device characterized in that it is equipped with a gas shielding means for preventing