JPH0249640Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention is based on a matrix type fuel cell, in particular, in which the number of single cells required to obtain a predetermined output is stacked in series, and a reactant gas is supplied to the cells. Regarding the structure of the cell stack.

[Prior art and its problems]

Fuel cells are well known as energy conversion devices that utilize electrochemical reactions to directly convert the chemical energy of fuel into electrical energy, aiming at highly efficient power generation. The single cell that forms the basis of the above-mentioned matrix fuel cell consists of a matrix impregnated with an electrolyte, for example, phosphoric acid, and a pair of porous electrodes placed on both sides of the matrix.
Through these electrodes, fuel gas (generally hydrogen gas is used) is supplied from one side and oxidizing gas (generally air is used) from the other side, and electrical energy is extracted directly from both electrodes. There is. In this case, the output obtained from the above single cells is 1V or less, and in order to obtain the required output as a practical power source, the required number of single cells must be combined in series or parallel to form a cell stack as the fuel cell itself. ing.

On the other hand, in order for the above battery body to operate normally, it is necessary to supply reactive gas uniformly to each cell, and the specific structure for this purpose is the ribbed electrode type shown below. , a ribbed separator type has been developed. Figures 1 and 2 show the battery structure for one cell of each type, where 1 is the matrix impregnated with electrolyte, 2 is the catalyst layer of the fuel electrode, and 3 is the air electrode. This is the catalyst layer. In the ribbed electrode type shown in FIG. 1, the aforementioned fuel electrode catalyst layer 2 and air electrode catalyst layer are formed on the plate surfaces of ribbed electrode base materials 4 and 5 made of gas-permeable porous carbon plates, respectively. Layer 3 is laminated, electrode base materials 4 and 5 are overlapped with matrix 1 in between, and fuel gas and air are flowed from the outside as shown by the arrow between the ribs of electrode base materials 4 and 5 to form electrodes 2 and 5. 3
Supplies reaction gas to. In addition, the ribbed electrode type uses a gas-impermeable conductive material to prevent fuel gas and air from mixing between the stacked cells and to electrically connect the cells. The produced separate plate 6 is inserted between adjacent unit cells.

On the other hand, the ribbed separator type shown in FIG. 2 is called a bipolar plate, and has reactant gas passage grooves perpendicular to each other on both surfaces.

Using ribbed separators 7 and 8 made of gas-impermeable carbon plates, a single cell assembly consisting of a matrix 1, a fuel electrode layer 2, and an air electrode layer 3 is sandwiched from both sides in a sandwich-like manner. It consists of

Next, FIGS. 3 and 4 show a conventional structure for supplying reactive gas to a cell stack constructed using the ribbed separator type as an example. That is, the cell stack 9 is constructed by alternately stacking the single cells and the ribbed separators described in FIG. 2, and stacking them one above the other in such a number that a predetermined output can be obtained. Furthermore, a pair of manifolds 10, 11 and 12, 13, which communicate with the fuel and oxidant reaction gas passages formed in the bipolar plate, are in close contact with the front, left, right and left circumferential surfaces of the cell stack 9. It is deployed. Of these, 10 and 11 are inlet and outlet manifolds for supplying fuel gas, 12,
Reference numeral 13 denotes an inlet and an outlet manifold for air supply, which are connected to air and fuel gas supply lines (not shown), respectively.

By the way, as mentioned above, the manifold 10 is common to all the cells making up the cell stack 9.
The conventional structure configured to supply the reactant gas through 13 has the following disadvantages. In other words, if even one defective cell occurs during operation, it is necessary to disassemble the entire battery including the manifold to replace it, which is very time-consuming and reduces the reliability of the cell stack. is low.

[Purpose of invention]

This invention was developed in consideration of the above points, and aims to provide a fuel cell cell stack structure that eliminates the drawbacks of the conventional structure, is easy to maintain, repair, etc., and has high reliability. With the goal.

[Key points of the idea]

In order to achieve the above object, this invention has a pair of reactant gas supply and discharge channels for oxidizing gas and fuel gas, which are connected to the reactant gas passage inside the cell, on the circumferential side of a cell stack formed by stacking unit cells. In a fuel cell equipped with a manifold and supplying reactant gas to the cell stack through this manifold, the cell stack is composed of a stacked assembly of independently constructed cell blocks with a predetermined number of unit cell stacks as a unit, and each cell block is To,
The pair of reactant gas supply and discharge manifolds are individually arranged, and the reactant gas supply and discharge manifolds are connected in parallel with the reaction gas supply and discharge lines, thereby supplying and discharging the reactant gas. Assembly, disassembly, and testing of cell stacks can be performed on a cell block basis.

[Example of idea]

FIG. 5 shows a cell block constructed based on this invention, and FIGS. 6 and 7 show examples of the construction of the cell stack and the reaction gas supply system. First, in FIG. 5, the cell block 14 is
A cooling plate 16 and a current collector plate 17 are arranged at both the upper and lower ends of a stack 15 of several tens of cells whose number is set in advance, and a predetermined tightening pressure is applied to this stack to assemble it integrally. as an independent structure.
Note that a terminal portion 18 is formed on the current collector plate 17 and projects to the side of the cell stack. A cell stack is constructed by stacking a plurality of cell blocks 14 one above the other in accordance with a desired output. By the way, with this invention, the above-mentioned cell block 14 is used as a unit, and manifolds 10' and 1 exclusively for the cell block are provided on the circumferential side of each cell block.
1', 12', and 13' are provided. Note that each manifold is manufactured as a standard product whose size is determined according to the dimensions of the cell block 14. FIG. 6 shows a cell stack structure in which a plurality of cell blocks 14 shown in FIG. For gas supply, as shown in FIG.
are connected in parallel via piping. Although FIG. 7 shows the fuel gas supply system, the air supply system is also connected via piping in the same manner. In addition, a gas flow rate adjustment valve 21 is inserted in each branch line 20, especially on the inlet side to the manifold, so that the flow rate of reaction gas supplied to the manifold dedicated to each cell block is made uniform through this adjustment valve 21. Adjustment controlled.

With the above configuration, when the cell is in operation, the fuel and oxidizer reaction gases are branched from their respective supply lines to the branch lines, and uniformly supplied to each cell block 14 through the valve 21 and the manifolds 10' and 12' on the inlet side. It turns out. If a defective cell occurs during operation, short-circuit the current collector plate terminals of the cell block containing the defective cell, close the valve 21 corresponding to the cell block, and stop the supply of reaction gas. By doing so, immediate emergency measures can be easily taken, and operation can be continued without any practical problems with only a slight decrease in output. Also, when you stop the operation and replace the defective battery,
Since cell blocks containing defective cells can be replaced as a unit, disassembly and assembly operations required for repair can be easily and quickly performed, and battery performance tests can also be freely performed on a cell block basis.

Although the illustrated embodiment shows an example of a ribbed separator type battery, it goes without saying that the present invention can also be implemented in the same manner when the cell stack is constructed of ribbed electrode type batteries. Furthermore, between the fuel gas and air, the air can be supplied by using the container housing the cell stack itself as a wind cylinder, without employing a manifold.

[Effect of idea]

As described above, according to this invention, a pair of reactant gas supply and discharge manifolds for oxidizing gas and fuel gas are provided on the circumferential side of a cell stack formed by stacking unit cells, which communicates with the reactant gas passage inside the cell. In a fuel cell in which a reactant gas is supplied to the cell stack through this manifold, the cell stack is composed of a laminated assembly of independently constructed cell blocks each having a predetermined number of unit cell stacks as a unit. , the pair of reactant gas supply and discharge manifolds are individually arranged, and the reactant gas supply and discharge manifolds are connected in parallel with the reaction gas supply and discharge lines, thereby improving the conventional method. Compared to the integrated type, the amount of reactant gas supplied to each unit cell is equalized. Furthermore, since the cell block can be assembled into a cell stack and its quality can be controlled on a cell block basis, advantages such as ease of handling such as assembly and disassembly of the cell stack and improved reliability can be obtained. If one type of manifold is prepared in advance as a standard product with dimensions matching the size of the cell block, it will be possible to handle fuel cells with different outputs. Parts management can be significantly streamlined compared to the previous version. In addition, each manifold is smaller than a conventional integrated structure, which reduces the difference in thermal expansion and contraction between the cell stack and the manifold, reducing the effects of thermal strain on the seal and component materials. It also has other accompanying effects.

[Brief explanation of the drawing]

Figures 1 and 2 are exploded perspective views of one-cell batteries configured as a ribbed electrode type and a ribbed separator type, respectively, and Figures 3 and 4 are exploded perspective views of a conventional cell stack structure and a manifold. Schematic diagrams of the assembled state, Figures 5 to 7 show examples of this invention. Figure 5 is a perspective view of the structure of the cell block, Figure 6 is an assembled diagram of the cell stack, and Figure 7 shows the reaction gas supply. It is a system diagram. 10'-13'...Manifold, 14...Cell block, 15...Single cell stack, 17...Current plate, 18...Terminal part, 19...Reactant gas supply line, 20...Branch line, 21...Flow rate adjustment valve.

Claims (1)

[Claims for Utility Model Registration] 1. A pair of reactive gas supplies for oxidizing gas and fuel gas, which are connected to a reactive gas passage inside the cell, on the peripheral side of a cell stack formed by stacking unit cells;
In a fuel cell in which a discharge manifold is provided and a reactant gas is supplied to a cell stack through this manifold, the cell stack is constituted by a stacked assembly of independently constructed cell blocks each having a predetermined number of unit cell stacks as a unit, and The pair of reaction gas supply and discharge manifolds are individually arranged for each cell block, and the reaction gas supply and discharge manifolds and the reaction gas supply and discharge lines are connected in parallel. fuel cell. 2. The fuel cell according to claim 1 of the utility model registration claim, characterized in that a flow rate regulating valve is inserted in each branch line that connects the reaction gas supply manifold and the reaction gas supply line in parallel. battery. 3. In the fuel cell described in Claim 1 of the Utility Model Registration Claim, current collector plates are provided at both ends of the unit cell stack for each cell block, each having a terminal portion protruding to the side of the cell stack. Characteristic fuel cells.