JPH10261426A - Block structure of fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a block structure of a fuel cell stack to facilitate replacement of a unit cell exhibiting poor performance and to enable uniform fastening of the laminated unit cell. SOLUTION: A block 1 is constituted by pinching a stack formed by laminating fuel cells between upper and lower plates having conductivity. Several stages of the block 1 are superposed to form a laminated block to be pinched between an upper keeping plate 12 and a lower keeping plate 11 which are fastened by a block keeping bolt 13. A reaction gas passage is vertically provided on one of right and left sides of the block 1, and an exhaust gas passage is vertically provided on the other thereof. When the block 1 is laminated, the connection between reaction passages or exhaust gas passages is established.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a block structure of a fuel cell stack in which a stack formed by stacking fuel cells is used as a block, and this block is stacked.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have features not found in conventional power generators, such as high efficiency and low environmental impact, and have attracted attention as power generation systems following hydro, thermal and nuclear power. Currently, intensive research is underway.

FIG. 4 is a schematic diagram showing a configuration of a molten carbonate fuel cell. The fuel cell has a low voltage (0.8
V), the battery is practically used as a multi-tiered battery with a separator interposed therebetween. This stacked battery is called a stack. The single cell 20 is composed of an electrolyte plate 2 made of a porous tile.
1 and a cathode (air electrode) 2 provided on one surface thereof
2 and an anode (fuel electrode) 23 provided on the other surface
The anode 22 has a flow path for flowing the cathode gas, and the anode 23 has a flow path for flowing the anode gas. The separator 24 is separated from the adjacent cells.

FIG. 5 is a plan view of a single cell 20. On both sides of the single cell 20, manifolds 30 and 32 for passing cathode gas and anode gas, and manifolds 31 and 33 for passing cathode exhaust gas and anode exhaust gas generated by the battery reaction.
Are provided to supply the respective gases to the cathode 22 and the anode 23 and to discharge the cathode exhaust gas and the anode exhaust gas generated by the battery reaction.

FIG. 6 is a cross-sectional view taken along line XX of FIG. 5 and shows the flow paths of the cathode gas and the cathode exhaust gas. One of the right and left sides of the unit cell 20, for example, the left side is the cathode gas manifold 3.
0, each cathode gas flow path 34 penetrates in a vertical direction through each unit cell 20 in which
Is supplied with a cathode gas. The right side vertically penetrates each unit cell 20 on which the cathode exhaust gas manifold 31 is stacked, and discharges the cathode exhaust gas generated by the battery reaction in each cathode gas flow path 34.

FIG. 7 is a cross-sectional view taken along the line YY of FIG. 5 and shows the flow paths of the anode gas and the anode exhaust gas. One of the left and right sides of the unit cell 20, for example, the left side is the anode gas manifold 3
Each anode gas flow path 35 that penetrates vertically through each unit cell 20 in which
Is supplied with anode gas. The right side vertically penetrates each unit cell 20 on which the anode exhaust gas manifold 33 is stacked, and discharges the anode exhaust gas generated by the battery reaction in each anode gas flow path 35.

A fuel cell has a stack structure in which several hundred single cells are stacked in order to obtain a large output. Such a stack includes a battery member (electrolyte plate 21, anode 23, cathode 22) and a separator on a metal body having a structure called a holder for supplying a fuel gas (anode gas) and an oxidizing gas (cathode gas) to the battery. 24 are stacked in several hundred steps.

[0008]

With such a structure in which battery members and separators are stacked in hundreds of stages, when a single cell having deteriorated performance occurs, only the deteriorated single cell is regarded as a healthy single cell. It is extremely difficult to replace. In addition, since the unit cell has a structure in which a large number of thin plate members having a large area are stacked and tightened from above and below, uniform tightening cannot be performed, and a temperature rise due to battery operation (battery reaction occurs at 600 to 700 ° C. in the battery). Is performed), and distortion tends to occur in the battery.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a block structure of a fuel cell stack in which single cells having poor performance can be easily replaced and stacked single cells can be uniformly tightened. With the goal.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, a fuel cell stack is sandwiched between conductive upper and lower plates to form a block,
A laminated block in which the blocks are stacked in a plurality of stages is sandwiched between an upper holding plate and a lower holding plate, and the upper holding plate and the lower holding plate are fastened with block holding bolts. Are provided vertically, and the other is provided with an exhaust gas passage vertically. When the blocks are stacked, the reaction gas passages and the exhaust gas passages are connected to each other.

A plurality of fuel cells (single cells) are stacked to form a stack, a block is sandwiched between an upper plate and a lower plate, and the blocks are stacked to form a structure in which a plurality of single cells are stacked. The fuel cell device can be easily manufactured. If there is a defective single cell, the repair work is facilitated by replacing the entire block including the defective single cell. Since the upper and lower plates of the block are conductive, they are electrically connected even when the blocks are stacked. In addition, the reaction gas (cathode gas, anode gas) passage and exhaust gas (cathode exhaust gas, anode exhaust gas) passage provided in each block are connected and connected to the block, so that these gases are supplied to and discharged from each unit cell. It is not necessary to separately provide a supply pipe and a discharge pipe for performing the operation outside the stack.

According to the second aspect of the present invention, an electrical insulating material is provided between the upper holding plate and the upper plate of the uppermost block.

By providing an electrically insulating material between the upper holding plate and the upper plate of the uppermost block, the uppermost block and the upper holding plate are electrically insulated from each other, and the uppermost block and the upper holding plate are electrically connected via the block holding bolts. An electrical short circuit between the block and the lowermost block can be prevented.

According to the third aspect of the present invention, the block holding bolt is electrically insulated from at least one of the upper holding plate and the lower holding plate.

By electrically insulating the block holding bolt and at least one of the upper holding plate and the lower holding plate, the uppermost block and the lowermost block are electrically short-circuited via the block holding bolt. Can be prevented.

According to a fourth aspect of the present invention, the block is configured by tightening an upper plate and a lower plate with stack holding bolts.

By tightening each unit cell constituting the block with the stack holding bolt, uniform tightening becomes possible.

In the invention according to claim 5, the stack holding bolt is electrically insulated from at least one of the upper plate and the lower plate.

By electrically insulating the stack holding bolt from at least one of the upper plate and the lower plate, it is possible to prevent the upper plate and the lower plate from being electrically short-circuited via the stack holding bolt. . This facilitates replacement of bad blocks.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a block of a fuel cell stack according to an embodiment of the present invention. The stack block 1 sandwiches a stack 2 formed by stacking ten to several tens of single cells described in FIG. 4 between a metal upper plate 3 and a lower plate 4, and holds both ends of the upper and lower plates 3 and 4 with stack holding bolts. 7 is uniformly tightened. Since the stack block 1 has a small number of stacked single cells, it is easy to uniformly tighten the stack blocks. Each single cell has an opening through which a reaction gas (cathode gas, anode gas) and exhaust gas pass, as described in FIG. 5, and when the single cells are stacked, a vertical direction as described in FIGS. Is formed. This manifold also penetrates the upper plate 3 and the lower plate 4, and a metal gasket 6 is provided on the upper surface of the upper plate 3 and the lower surface of the lower plate 4 at the penetrating position, so that the gas leaks when the stack blocks 1 are stacked. To prevent.

FIG. 2 shows stack blocks 1 of several stages to several tens.
This shows a state in which a fuel cell device is configured by stacking the fuel cells in stages. In the fuel cell device 10, several to several tens of stack blocks 1 are stacked on a lower holding plate 11, a bellows 18 is provided on an upper end, an upper holding plate 12 is provided on the bellows 18, and a lower holding plate 11 is provided. And the upper holding plate 12 are tightened with the block holding bolts 13. A reactive gas supply header 14 is provided at one end of the lower holding plate 11, and is connected to the manifold 5 of the stack block 1 by a gas guide path 16 provided in the lower holding plate 11. At the other end, a reaction exhaust gas discharge header 15 is provided, which is connected to the manifold 5 of the stack block 1 by a gas guide path 16 provided in the lower holding plate 11. An insulating plate 17 is provided between the lower surface of the bellows 18 and the uppermost stack block 1. The lowermost and uppermost stack blocks are provided via the bellows 18, the upper holding plate 12, the block holding bolts 13 and the lower holding plate 11. 1 is prevented from being electrically short-circuited.
A bellows pressure adjusting device 19a is connected to the bellows 18, and adjusts the pressure in the bellows 18 to adjust the tightening force of the stack block 1. The gas used for pressure adjustment is supplied from a gas cylinder 19b. Nitrogen gas or air is used as the gas. Note that a spring may be used instead of the bellows 18.

A stack holding bolt 7 is provided on the left side of the stacked stack blocks 1, and the stack holding bolt 7 is removed on the right side. The left side shows the case where the stack holding bolt 7 is insulated from at least one of the upper plate 3 and the lower plate 4, and the right side electrically shorts the upper plate 3 and the lower plate 4 via the stack holding bolt 7. After stacking the stack blocks 1, the stack holding bolts 7
The figure shows the case where is removed. Usually, the stack holding bolt 7 is either left or removed on both sides.

FIG. 3 shows an insulating structure between a bolt and a plate to be tightened by the bolt. A cylindrical sleeve insulating material 42 is fitted into the bolt hole of the plate 44 to insulate the bolt 40 from the plate 44. A flat plate insulating material 43 is provided between the plate 44 and the nut 41 to insulate the nut 41 from the plate 44.
This insulating structure can be applied to the stack holding bolt 7 and the block holding bolt 13. If this insulating structure is adopted for the block holding bolt 13, the insulating plate 17 can be omitted. Further, when the stack holding bolt 7 is employed, the stack holding bolt 7 may be attached during operation as shown on the left side of FIG. This makes it easy to replace the block, and it is possible to always maintain a uniform tightening force.

[0024]

As is apparent from the above description, according to the present invention, a stack can be uniformly tightened by manufacturing a stack in block units and stacking the stacks. In addition, manufacture and assembly are facilitated, and replacement of blocks including defective single cells is facilitated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a stack block according to an embodiment of the present invention.

FIG. 2 is a diagram showing a fuel cell device in which stack blocks are stacked.

FIG. 3 is a view showing an insulating bolt structure.

FIG. 4 is a schematic diagram showing a single cell structure of a fuel cell.

FIG. 5 is a plan view of a single cell.

FIG. 6 is a sectional view taken along line XX of FIG. 5;

FIG. 7 is a sectional view taken along line YY of FIG. 5;

[Description of Signs] 1 Stack block 2 Stack 3 Upper plate 4 Lower plate 5 Manifold 6 Metal gasket 7 Stack holding bolt 10 Fuel cell device 11 Lower holding plate 12 Upper holding plate 13 Block holding bolt 14 Reaction gas supply header 15 Reaction gas exhaust gas Header 16 Gas guide path 17 Insulating plate 18 Bellows 19a Bellows pressure regulator 19b Gas cylinder 40 Bolt 41 Nut 42 Sleeve insulating material 43 Plate insulating material 44 Plate

Claims (5)

[Claims] 1. A block formed by stacking a stack of fuel cells between conductive upper and lower plates, and a stacked block in which a plurality of blocks are stacked is sandwiched between an upper holding plate and a lower holding plate. The upper holding plate and the lower holding plate are fastened with block holding bolts, and a reactive gas path is provided vertically on one of the left and right sides of the block, and an exhaust gas path is provided vertically on the other side. A block structure of a fuel cell stack, wherein the reaction gas passages and the exhaust gas passages are connected to each other. 2. The block structure of a fuel cell stack according to claim 1, wherein an electrical insulating material is provided between the upper holding plate and the upper plate of the uppermost block. 3. The block structure of a fuel cell stack according to claim 1, wherein the block holding bolt and at least one of an upper holding plate and a lower holding plate are electrically insulated. 4. The block structure of a fuel cell stack according to claim 1, wherein said block is formed by fastening an upper plate and a lower plate with stack holding bolts. 5. The block structure of a fuel cell stack according to claim 1, wherein the stack holding bolt is electrically insulated from at least one of the upper plate and the lower plate.