JPS61239568A - Fuel cell stack - Google Patents

Abstract

PURPOSE:To realize miniaturization and improve heat efficiency, by performing a press deep drawing processing on separators and providing a pressure chamber for either an upper holder or a lower holder in a stack so as to have the separators act in the direction in which electrodes hold electrolyte tiles. CONSTITUTION:Separators are of corrugation type in which heat-resisting sheet iron plates are press-molded. In order to obtain more uniform contact pressure between electrodes 2, 3 and tiles 1, pressure chambers 22 and 23 are provided respectively between an upper holder 10 and separators 4, and between a lower holder 9 and separators 4. Pressure fluid is supplied respectively into the pressure chamber 22 from a pressure port 24 equipped in the upper holder 10, and into the pressure chamber 23 from a pressure port 25 equipped in the lower holder 9. Thus, because the upper separators 4 and lower ones 4 are deformed respectively downward and upwards, fastening strength can be uniformalized between the electrodes 2, 3 and tiles 1.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fuel cell stack in which fuel cells are stacked in multiple layers to be used in the energy sector for directly converting the chemical energy of fuel into electrical energy. It is.

[Conventional technology]

In a fuel cell stack, an electrolyte tile, which is a component of a fuel cell, is sandwiched between the upper and lower sides by a cathode, which is an air electrode, and an anode, which is a fuel electrode.Air is supplied to the cathode side, and air is supplied to the anode side ( 2. Units that generate power by the potential difference generated between the It refers to one whole that is fixed with a certain tightening force.
1 Fuel cells directly convert the chemical energy of LNG, coal gas, etc. into electrical energy, so compared to conventional power generation methods (chemical energy → [thermal energy → mechanical energy → electrical energy --), fuel cells generate the following: There is merit 0
;.

■ High because there is no restriction of Carnot cycle [Efficiency can be expected 0 1■
There are no rotating parts, so there is less noise.

■ Effective heat generation can be obtained at a relatively high temperature close to the battery operating temperature.

■ Efficiency does not change much even if the output is changed.

■ No size restrictions.

■ Sequential expansion is possible.

Since fuel cells have many frits that are divided into two parts, research into fuel cells has progressed, and progress has been made in the development of fuel cell stacks in which the cathode and anode electrodes are pressed against the electrolyte tile with uniform pressure. It is being

[Problem that the invention seeks to solve]

However, half of the total cost of a fuel cell system is the stack body, which is made up of electrolyte tiles and electrodes laminated in multiple layers with separators in between. It takes up a lot of weight. The groove machining of the separator is intended to form a passage that often obstructs the flow of the working fluid, and at the same time to form a protrusion that allows the electrode to press and contact the electrolyte tile. , As shown in Figure 5, grooves are processed using an end mill to form protrusions (
a) is formed, and the pitch (p) of the grooves (b) is 4 to 5 pitches. In addition, it is necessary to ensure the flatness of the top of the projection (a) in order to contact the electrode with the tile, so the thickness of the separator is increased, so when stacked, the total height of the stack is It has the disadvantage of being high.

Furthermore, as shown in Fig. 6, the electrochemical reaction of the fuel cell occurs at a location where six phases exist: the working gas (C1), the liquid electrolyte tile (A), and the solid phase electrode. By pressing against the electrolyte tile (A), a 6-phase mixture area is generated near the electrode contact point, but creating a large number of 5-phase mixture areas will lead to efficient power generation. 0 is molten salt.On the other hand In conventional fuel cell stacks, it is necessary to prevent the leakage of the working fluid from the stack body, and at the same time it is necessary to press the electrodes uniformly against the electrolyte tiles (A), and the fuel cell components are highly sophisticated. Machining precision is required.Also, tiles impregnated with electrolyte (A)
If it is not tightened for a long time, it will cause a creep phenomenon.
A pressing method is required for the pressing force to follow this amount of shrinkage.

Therefore, the present invention aims to provide a fuel cell stack that can reduce costs, reduce size, improve thermal efficiency, and the like.

[Failure to solve the problem]

The present invention applies deep press processing to a separator that separates two types of working fluids supplied to different electrodes, and uses the separator to equalize the contact pressure of the electrodes to the electrolyte tiles at least at the top or bottom of the stack. A pressure chamber is provided on one side of the holder, and the fluid pressurized into the pressure chamber acts on the separator in a direction in which the electrodes clamp the electrolyte tile.

[For production]

"When a fluid with a pressure higher than the pressure of the working fluid supplied to the electrode is supplied to the pressure chambers provided in the second part and the lower holder,
This pressure pushes the separator and equalizes the contact pressure between the electrolyte tile and the electrode, resulting in a two-part equal contact pressure due to the clamping force of the stack plus the pressure in the pressure chamber. Potassium, the electrochemical reaction becomes more efficient. Furthermore, since the separator is deep-drawn to form protrusions that bring the working fluid passage and electrode into contact with the electrolyte tile, it can be manufactured thinly and inexpensively, reducing the overall height of the stack and making it more compact.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show embodiments of the present invention, and FIG. 4 shows the overall structure of the separated fuel cell stack of the present invention.

A corrugated separator (4) made by press-forming a heat-resistant thin steel plate, an electrolyte tile (1), and an electrode (cathode)
(2), an electrode (anode) (3), a punching plate (5), and a distance plate 1-(6) (7) each having a hollowed out part (8). Place the separator (4) through the distance plate (6) on the lower holder (91) having an internal manifold function, and place the distance plate (6) (7) on the upper protrusion of the separator (4).
) is placed on the punching plate 1 (5) of a size that can fit into each internal cutout (8), and then the electrode (3) is placed.
) through the electrolyte tile fl), and this tile (1
) on which are the electrode (2) and the punching plate (5).
) and the separator (4) in this order, and the two-part separator (4) has its peripheral part placed on the distance piece (6).
Place the electrode (2) on the top and bottom of the tile (11).
3), punching play) (5), separator (4)
) are stacked in multiple layers, and an upper holder (10) is placed on a part of the upper holder (10).
) and the lower holder (9).
) by connecting the ears (12) that protrude horizontally with the vertical tie rod (1 wing) and tightening them.
Make it possible to obtain a stack that is a body structure.

A supply hole 04 for supplying a working fluid (for example, air + carbon dioxide) to the electrode (cathode) (2) of each layer in the laminated stack and a discharge hole (15) for discharging the working fluid. , the tiles (1), diskunsphere) (6) (
71, a supply hole (+6) is formed to pass through the negative side and the other side of the separator (4), and is used to supply working fluid (fuel) to the electrode (anode) (3) of each layer. ) and the discharge hole 0η for discharging the working fluid, in the same way as above, the tile (1) and the tistance plate (6) of each layer.
) (force, on the − side and the other side of the separator (4),
Two air holes (+4) and (+51) are provided so as to be alternately arranged.

Distance play above) (Of 61(7), distance play 1-(6) on the electrode (cathode) side is
The two-part supply hole θ4) and the discharge hole (15) are opened in the internal hollowed out part (8), and the air and carbon dioxide gas supplied from the supply hole 04) are supplied to the internal hollowed out part in each distance play 1-(6) part. (8) while flowing from the supply side to the discharge side, passing through the punching plate (5) and forming the electrode (cathode).
(2) Supply to the electrode (anode)
(3) side distance plate (force is fuel
: The supply hole (+6) and the discharge hole (+7) are all opened in the internal hollowed out part (8), and in the distance play 1- (7) part, fuel flows from the supply side to the discharge side, and during this time, the fuel flows from the supply side to the discharge side. It passes through a punching plate (5) and is supplied to an electrode (anode) (3).

The power to supply electrodes (2) (3), tiles (1), spacers (4), etc. is provided by connecting the two parts and the ears (11) α2 attached to the lower holder (IQ (9)) and the tie rod (through the holes) between them. ,
This can be easily generated by tightening the insulating material (1, 8>, disc spring (19), and collar (21) through the collar (20), but the feature of the present invention is that the electrode (2) (In order to obtain more uniform contact pressure between 31 and tile (1), upper holder 00) and separator (
4) and between the lower holder (9) and the separator (4)
Pressure chambers (22) and (23) are provided between the upper holder (10) and the pressure chamber (22), respectively. Upper separator (4) by supplying pressure fluid from capo-1□ (25) to pressure chambers (23) respectively.
is deformed downward, and the lower separator (4) is deformed upward to equalize the clamping force between the electrode (2) (3+ and the tile (1) 7゛71'') K u (h 2w t l f
,! +6・: □ (2G) is the bow 1- provided on the lower holder (9) so as to communicate with the air and carbon dioxide gas supply hole (14), (27) is the bow 1- provided on the lower holder (9) so as to communicate with the air exhaust hole Q, 51. 9) , (2)
8) Lower part that communicates with the ld fuel supply hole (16)
The bow 1-, (29) provided on the i-holder (9) is connected to the lower holder (9) so that it communicates with the fuel discharge hole 0η1.
): is the port provided. Further, (to) there is an electrolysis chamber formed on the upper surface of the upper holder (10), and the reservoir, 1
．． )(30). 8 corners. Electrolyte is supplied to each tile (1) from the supplementary supply hole 01). (3
1) is a spacer.

Note that the above-mentioned insulating material 08) is resistant to high temperature atmosphere.
1. It is made of ceramics and has an upper and lower holder.
The plate spring (10 is made of heat-resistant steel, and the clamping force follows the creep of the tile (1) due to the clamping force). It is necessary to keep the power extremely constant. An alternative way to follow the creep of tile (1) is to
: I am also thinking of pressing it with a cylinder that does not work.
´Reru.

Further, in FIG. 4, the punching plate (5) is not shown.

Now, when fuel is supplied from the port (28) of the lower holder (9), this working fluid rises through the supply hole (16) and reaches the separator (4) in the distance play 1- (7) section.
) flows from the discharge side port of the distance plate (7) through the discharge hole (17) to the lower holder (9).
) outflows from (29). Also, when air and carbon dioxide are supplied through the bow (26) of the lower holder (9), this working fluid rises through the supply hole (04), causing the separator (4) to rise at the tension plate (6). It flows from the bottom of the distance plate (61) through the discharge hole (15) and flows out from the hole (27) of the lower holder (9).

The fuel-side working fluid led to the upper side of the separator (4) passes through the holes in the punching plate 1- (51) to the electrode (
The air-side working fluid supplied to the anode) (3) and led to the lower side of the separator (4) is fed to the punching plate 1 (
It is supplied to the electrode (cathode) (2) through the hole in 5).

As for the leakage of the working fluid supplied above, the separator (
4), distance play 1- (61 and (external leakage from the force sealing surface and each supply hole (] 4) (16)
There are internal leaks such as leaks between the drain holes (+51 (19), leaks due to differential pressure between tiles, etc.).Leaks other than leaks due to differential pressure between tiles are caused by stack tightening force, part processing accuracy, electrode and It is mainly controlled by the tightening force of the tile, etc. In other words, if the tightening force is kept constant, if an attempt is made to prevent leakage, the tightening force between the electrode (2) (31 and the tile (1) will decrease. is also expected.

In the present invention, in order to break the inverse correlation between the two, pressure chambers (
A pressure higher than the working fluid pressure of air or fuel is applied to 22) and (23) to deform the separator (4) inward, thereby increasing the clamping force between the electrodes (2) and (3) and the tile (1). Efforts are being made to make these standards uniform. At this time, pressure chambers (22) (23
) The deformation of the separator (4) due to the pressure within the tile (1) causes local deformation in the periphery of the tile, which may cause damage to the tile (1). Since the spacer (4) is positioned, the tile (1
) can be alleviated.

The electrolyte in the tiles (1) reacts with the permeate flow due to the pressure difference between the tiles (1) and the water vapor present in the working fluid and dissipates, so it is necessary to replenish the electrolyte1'. Replenishment is carried out when the electrolyte stored in the reservoir (30) installed in the upper holder 00) and i 1 liquefies when it becomes hot and flows down the replenishment hole (31) provided in the two-part holder (10). This is done by infiltrating the tile (1).

Note that the present invention is not limited to the above-mentioned embodiments. For example, by applying pressure to the pressure chambers (22) (123), back pressure is applied to the separator (4).
As a result, a configuration was shown in which the force applied between the electrode (21 (31) and the tile (1) was equalized to 8. ka1
5.1 month □, □ month. Since the warping effect may be reduced, in this case, it is sufficient to provide pressure chambers with the same effect at multiple locations in the middle of the stack, and to It goes without saying that the relative arrangement is merely an example, and that various changes may be made without departing from the gist of the invention.

〔Effect of the invention〕

As described above, according to the fuel cell stack of the present invention, the following excellent effects can be achieved.

(1) Since the separator is made of a thin steel plate that has been deep-drawn by a press, manufacturing costs can be significantly lowered and the separator can be made smaller compared to conventional mechanical groove processing.

(11) Since the pressure chamber provided in the upper or lower holder applies back pressure to the separator to bring the electrode into uniform contact with the tile, in addition to the applied force of the stack, the contact pressure between the electrode and the tile It is possible to make the electrochemical reaction more uniform and to make the electrochemical reaction more efficient.

(iii) When the number of stages in the stack is large, by providing a pressure chamber at any intermediate position, the uniform contact pressure effect due to the back pressure of the separator will not be diminished as the number of stages increases.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the fuel cell stack of the present invention, and FIG.
The figure is the plan view of Fig. 1, and Fig. 61 is the l1l-it of Fig. 1.
4 is an example view when the stack is separated in the vertical direction, FIG. 5 is a perspective view of a separator in a conventional fuel cell stack, and FIG. 6 is a diagram showing the electrochemical reaction of the fuel cell. . (1) is an electrolyte tile, (2) (31 is an electrode, (4)
is the separator, (61f force is the distance plate, (
9) is the lower holder't (IOJ is the upper holder, (
131 is a tie rod, (14) (1, 6) is a supply hole, (
]51 (]7) indicates a discharge hole, and (22) and (23) indicate a pressure chamber.

Claims (1)

[Claims] 1) Fuel cell units consisting of electrolyte tiles sandwiched between electrodes are stacked in multiple layers with separators interposed between them, and placed between upper and lower holders, and passages for supplying and discharging different working fluids to the electrodes on both sides of the electrolyte tiles are provided. In a fuel cell stack formed by pressing upper and lower holders, the separator that partitions the two types of working fluids is deep-drawn, and at least between the upper holder and the separator or between the lower holder and the separator. 1. A fuel cell stack characterized in that a pressure chamber is provided between the fuel cell stack and the pressure chamber can be applied with pressure from the outside.