JPS63195967A - Fuel cell - Google Patents

Abstract

PURPOSE:To prevent the corrosion of pipelines caused by an electrolyte by locating a cooling water inlet pipeline and a cooling water outlet pipeline on gas return side stacked surface where no manifold is mounted. CONSTITUTION:A fuel gas return passage 16 is arranged at a nearly right angle to a fuel gas going passage and a fuel gas return passage so that a fuel gas can return on an anode 2 substrate. A cooling water pipe 11 and a cooling water outlet pipe 12 of a cooling pipe 10 which are embedded in a cooling plate 9 are located on a fuel gas return side stacked surface. Since the pipelines are located outside a manifold, the corrosion of the pipeline caused by a phosphoric acid electrolyte can be prevented. Even if the cooling water leaks from cooling water pipeline joints, that has practically no effect on the cells. Therefore, a fuel cell having high reliability can be obtained.

Description

[Detailed description of the invention] [Objective of the invention] (Industrial field of application) The present invention relates to a fuel cell, and in particular, the manifold on the gas return side stacked surface is omitted, and cooling pipes are provided on the gas return side stacked surface. The present invention relates to a fuel cell configured to locate water inlet and outlet piping sections.

(Prior Art) Fuel cells are conventionally known as devices that directly convert chemical energy contained in fuel into electrical energy. This fuel cell usually has a fuel electrode (hereinafter referred to as an anode) and an oxidizer electrode (hereinafter referred to as an anode electrode), which has a catalyst layer formed on one side with a matrix impregnated with an electrolyte sandwiched therebetween.
A pair of porous electrodes (hereinafter referred to as cathode electrodes) are arranged, and a fuel gas such as hydrogen gas is brought into contact with the back surface of the anode electrode, and an oxidizing gas such as air is brought into contact with the back surface of the cathode electrode. The electrochemical reaction that occurs at this time is used to extract electrical energy from between the two electric currents, and as long as the fuel gas and oxidizing gas are supplied, electrical energy can be extracted with high conversion efficiency. It is something that can be taken out.

FIG. 3 is a perspective view showing the configuration of a conventional unit cell in this type of fuel cell. In Figure 3, the unit cell is
A catalyst is applied to the surface in contact with the matrix 1 impregnated with an electrolyte, and an anode electrode 2 formed of a porous material is placed on the upper side, and a catalyst is applied to the surface in contact with the matrix 1, which is also formed of a porous material. The cathode electrode 3 is arranged on the lower side. The anode electrode 2 and the cathode electrode 3 each have a fuel gas flow path 4 on the opposite side of the matrix 1 through which the fuel gas and the oxidant gas flow.
and an oxidizing gas flow path 5 are provided in directions orthogonal to each other.

Generally, in a phosphoric acid fuel cell using phosphoric acid as an electrolyte, the fuel gas is hydrogen and the oxidant gas is oxygen in the air. Since the voltage generated by a fuel cell is as low as 1 volt or less, normally 400 to 500 unit cells 6 are separated by heat-resistant and phosphoric acid-resistant separators, as shown in the exploded perspective view of FIG. (hereinafter referred to as a laminated stack) to obtain a high voltage. In addition, since the above electrochemical reaction is an exothermic reaction, in order to prevent temperature rise when stacking unit cells 6, a cooling plate 9 is inserted and installed for every predetermined number of unit cells 6, and the heat generated by the fuel cell is The structure is such that the heat is extracted to the outside. Here, the cooling plate 9 is usually made of a compression-molded graphite resin composition, and as shown in the plan view in FIG. The book is embedded. Water is normally used as the refrigerant, and this water is introduced through the cooling water inlet pipe 11 and discharged through the cooling water outlet pipe 12.

However, the above-mentioned fuel cell has the following problems. That is, the cooling water inlet pipe 11 of the cooling pipe 10
Since the cooling water outlet pipe 12 is installed in a high-temperature, high-pressure phosphoric acid atmosphere in a manifold (not shown), even if a heat-resistant and corrosion-resistant coating material is applied, it is difficult to operate the fuel cell for a long time. There is a risk of corrosion. In addition, the cooling water inlet pipe 11 and the cooling water outlet pipe 12 of the cooling pipe 10 are connected to a cooling water supply pipe and a cooling water discharge pipe (not shown) outside the laminated stack via the manifold. Gas leakage of the supplied gas to the outside may occur. Furthermore, if cooling water leaks from the cooling pipes in the manifold due to loose connections, broken welds, etc., the cooling water will accumulate in the manifold and clog the cell supply gas flow path.

Major problems such as clogging of supply gas piping occur, which makes operation impossible.

(Problems to be Solved by the Invention) As described above, in conventional fuel cells, the cooling water inlet and outlet piping parts of the cooling pipes are corroded by the electrolyte (phosphoric acid), and the cooling water from the connecting parts of the cooling pipes, etc. There has been a problem in that water leakage occurs, leading to decreased reliability, shortened lifespan, and decreased performance of the fuel cell.

The present invention was made to solve the above-mentioned problems, and its purpose is to prevent corrosion caused by electrolyte at the cooling water inlet and outlet piping parts of cooling pipes, improve reliability, extend service life, and improve The object of the present invention is to provide a fuel cell whose performance can be improved.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the fuel cell of the present invention includes a pair of porous electrodes that are disposed opposite to each other with a matrix holding an electrolyte in between. parallel to the gas flow passages on the gas flow side of at least one electrode substrate of the unit cell that outputs electrical energy under conditions where the fuel gas and oxidant gas are flowing. A partition band is provided in the partition band, one side of the partition band is used as an outgoing path of the gas flow path, and the other side is used as a return path of the gas flow path, and a part of the partition band on the return side of the gas flow path is deleted.

A gas return passage is provided almost at right angles to the outgoing and incoming gas distribution paths so that the gas returns on the electrode substrate, and a plurality of unit cells having the above configuration are stacked by inserting and installing cooling plates for each of a predetermined number of unit cells. In addition, the cooling water inlet and outlet piping portions of the cooling pipes embedded in the cooling plate are located on the gas return side laminated surface.

(Function) In the above fuel cell, by providing a gas return passage in at least one porous electrode of the unit cell, gas returns on the electrode and one or two manifolds can be omitted. Can be done. In addition, by locating the cooling water inlet and outlet piping parts of the cooling pipes on the laminated surface on the gas return side where this manifold is omitted, corrosion of these piping parts due to electrolyte can be prevented, and furthermore, the cooling water piping can be prevented from being corroded by electrolyte. Even in the unlikely event that cooling water leaks from a connection part, etc., it will have almost no effect on the cell, and the reliability of the fuel cell can be increased, resulting in longer life and higher performance. Furthermore, since the piping section is located outside the manifold, piping work during lamination work is facilitated.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1(a) and 1(b) respectively show configuration examples of a fuel cell according to the present invention, FIG. 1(a) is a plan view showing details of the anode electrode, and FIG. 1(b) is a laminated layer of a stack. It is an enlarged view showing a surface. Note that in the first factors (a) and (b), the same parts as in FIGS. 3 to 5 are denoted by the same reference numerals.

First, in FIG. 1(a), a partition band 13 is provided in parallel with the fuel gas flow path near the center of the gas flow side of the anode electrode 2 substrate constituting the unit cell described above.
One side of the fuel gas flow path 3 is an outgoing path 14 of the fuel gas flow path, and the other side is a return path 15 of the fuel gas flow path. Then, a part of the partition band 13 on the return side of the fuel gas flow path is removed, and a fuel gas flow outward path 14 and a fuel gas return path 15 are created so that the fuel gas returns on the anode electrode 2 substrate.
A fuel gas return passage 16 is provided approximately at right angles to the. In addition, the unit cell 6 configured as described above is shown in FIG. 1 (1)).
As shown in the figure, a large number of cooling plates 9 are inserted and installed through a separator 7 and for each predetermined number of unit cells, and a large number of cooling plates 9 are stacked. The cooling water inlet pipe 11 and the cooling water outlet pipe 12 are located in the cooling water inlet pipe 11 and the cooling water outlet pipe 12.

In FIG. 1(a), 17 is a fuel gas inlet manifold, 18 is a fuel gas outlet manifold, and 19 is an edge seal portion.

Furthermore, since the configuration on the cathode electrode 3 side is exactly the same as described above, illustration and explanation thereof will be omitted here.

In the fuel cell configured as described above, the fuel gas supplied during operation is supplied to the fuel gas inlet manifold 17. The fuel gas returns through the fuel gas return passage 16 via the outgoing fuel gas distribution path 14, and returns to the fuel gas distribution inbound path 15. The fuel gas is discharged via the fuel gas outlet manifold 18. Further, in the operating state, the nitrogen pressure around the laminated stack is controlled to be the same as the supplied fuel gas and air pressure, so that the edge seal portion 19 is sufficiently airtight. On the other hand, the cooling water inlet pipe 11 and the cooling water outlet pipe 12 of the cooling pipe 10 located on the laminated surface on the fuel gas return side are not corroded by phosphoric acid because they are located in a nitrogen atmosphere in a pressure vessel (not shown). . Furthermore, even if cooling water leaks from a connection part of a cooling pipe or the like, the cooling water only accumulates in the pressure vessel and has almost no effect on the cell itself.

That is, in the fuel cells of the present embodiments and examples, the following effects can be obtained. First, since the fuel gas return passage 16 is formed in the anode electrode 2 of the unit cell, the fuel gas returns on the anode electrode 2, allowing the manifold that was conventionally disposed on the west side of the stack to be removed. One can be omitted, making it cheaper. In addition, since the cooling water inlet pipe 11 and the cooling water outlet pipe 12 of the cooling pipe 10 embedded in the cooling plate 9 are located on the stacked surface on the fuel gas return side of the part where this manifold is omitted, these By locating the piping section outside the manifold, it is possible to prevent corrosion caused by phosphoric acid, which is an electrolyte, and even in the unlikely event that cooling water leaks from the cooling water piping connection, there will be little damage to the cell. Since it does not affect the fuel cell, it is possible to improve the reliability of the fuel cell, extend its lifespan, and improve its performance. Furthermore, the cooling water inlet pipe 11 and the cooling water outlet pipe 1 of the cooling pipe 10
2 is located outside the manifold, it becomes possible to perform piping work extremely easily during stacking work.

It should be noted that the present invention is not limited to the above-described embodiments, but can be similarly implemented in the following manner.

In the above embodiment, the partition strip is provided only on the anode bridge 2 side, but the present invention is not limited to this, and a partition strip may also be provided on the cathode electrode 3 side. That is, as shown in the plan view in FIG. 2, a partition band 2o is provided on the cathode electrode 3 side as well as on the anode electrode 2 side, and the oxidant gas supplied during operation is passed through the oxidant gas artificial manifold 21. The oxygen-containing gas returns through the oxygen-containing gas return path 23 via the oxygen-containing gas distribution path 22, and returns to the oxygen-containing gas distribution path 24. The oxygen-containing gas may be discharged via the oxidizing gas outlet manifold 25.

When a large number of unit cells configured as described above are stacked, a total of two manifolds, not only one manifold on the fuel gas side but also one manifold on the oxidant gas side, can be omitted, so the U-shaped cooling pipes can be omitted. Section 26 can also be located outside the manifold. As a result, the cooling pipe 10. In addition to the cooling water inlet pipe 11 and the cooling water outlet pipe 12, the cooling pipe U
Since the portion 26 is also located in the nitrogen atmosphere within the pressure vessel, it is not corroded by phosphoric acid, making it possible to further improve the reliability of the fuel cell.

Further, in the above embodiment, the anode electrode 2 side may be left as is, and a partition band may be provided only on the cathode electrode 3 side.

In addition, the present invention can be modified and implemented in various ways without changing the gist thereof.

〔Effect of the invention〕

As explained above, according to the present invention, corrosion caused by electrolyte at the cooling water inlet and outlet piping portions of cooling pipes is prevented, reliability is improved, lifespan is extended, and performance is improved. It is possible to provide fuel cells with easy piping operations.

[Brief explanation of the drawing]

Figures 1 (a) and (1) respectively show one embodiment of the present invention, where Figure 1 (a) is a plan view showing details of the anode electrode, and Figure 1 (b) is a plan view of the laminated stack. FIG. 2 is an enlarged view showing the laminated surface; FIG. 2 is a plan view showing another embodiment of the present invention; FIG.
FIG. 4 is a perspective view showing the configuration of a unit cell in a conventional fuel cell, FIG. 4 is a perspective view showing the outer surface of a laminated stack in a conventional fuel cell, and FIG. 5 is a plan view showing a cooling plate in FIG. 4. 1... Matrix, 2... Anode electrode, 3...
- Cathode electrode, 4... Fuel gas flow path, 5... Oxidizing gas flow path, 6... Unit cell, 7... Separator, 9... Cooling plate, 10... Cooling pipe, 11...
Cooling water inlet pipe, 12... Cooling water outlet pipe, 13.20.
...Partition strip, 14...Fuel gas distribution outbound path, 15...
Fuel gas distribution return path, 16...Fuel gas return passage,
17...Fuel gas inlet manifold, 18...Fuel gas outlet manifold, 19...Edge seal portion, 2
DESCRIPTION OF SYMBOLS 1... Oxidizing gas inlet manifold, 22... Oxidizing gas distribution path, 23... Oxidizing gas return passage,
24... Oxidizing gas return path, 25... Oxidizing gas outlet manifold, 26... Cooling pipe U-shaped portion.

Claims (1)

[Claims] Electrical energy is supplied under conditions where fuel gas and oxidant gas are flowing through each of the fuel gas and oxidant gas flow paths provided in a pair of porous electrodes that are placed opposite each other with a matrix holding an electrolyte in between. A partition strip is provided on the gas flow side of at least one electrode substrate of the output unit cell in parallel with the gas flow path, one side of the partition band is used as the outgoing path of the gas flow path, and the other side is used as the return path of the gas flow path. , a part of the gas flow path return side of the partition band is removed, and a gas return path is provided approximately at right angles to the gas flow outbound path and inbound path so that the gas returns on the electrode substrate, and further a unit having the above configuration is provided. A plurality of cells are stacked by inserting a cooling plate into each unit cell of a predetermined number, and the cooling water inlet and outlet piping portions of the cooling pipes embedded in the cooling plate are located on the stacked surface on the gas return side. A fuel cell characterized by: