JPH11260389A - Inspection method of separator for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method capable of sensitively detecting leakage through a small diameter through-hole and preventing breakages, even in the inspection of a large area separator. SOLUTION: A first manifold 11A and a second manifold 11C are arranged on each main surface of a separator 10, helium gas in a gas cylinder 13 is supplied to the inside of the first manifold 11A to pressurize to low pressure and its pressure is held, and nitrogen gas is introduced into the inside of the second manifold 11C from a gas inlet opening 20 installed on the side surface, and exhausted from a gas exhausting opening 21 installed on the other side surface, part of the exhausted gas is sucked, helium gas concentration is measured, and by multiplying the measured value with the gas flow rate obtained through a gas flow meter, helium gas penetration amount to the separator 10 can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for testing a separator inserted between unit cells of a stacked fuel cell, and more particularly to a method for testing gas permeability.

[0002]

2. Description of the Related Art FIG. 2 is an exploded perspective view of a main part showing a basic structure of a stacked fuel cell. As shown in the figure, a fuel electrode 3 is closely attached to one main surface of a flat matrix 2 holding phosphoric acid as an electrolyte, and an oxidizer electrode 4 is closely adhered to the other main surface. Are formed on the outer surface of the fuel electrode 3, a gas-permeable porous substrate 5 having a fuel gas flow path 7, and on the outer surface of the oxidant electrode 4, an oxidant gas flow path 8
And a gas-permeable porous substrate 6 having the following. In this configuration, the fuel gas containing high-concentration hydrogen gas flows through the fuel gas flow path 7 and is supplied to the fuel electrode 3, and the oxidant gas containing oxygen flows through the oxidizing gas flow path 8 and the oxidant electrode If it supplies to 4, electric energy will be obtained by an electrochemical reaction. However, since the generated voltage obtained by one unit cell is a low voltage of less than 1 V, a method of increasing the generated voltage by stacking a plurality of unit cells while interposing the separator 10 and electrically connecting them in series. Is adopted. For this reason, one surface of the interposed separator 10 has a fuel gas atmosphere, and the other surface has an oxidizing agent atmosphere. Therefore, the separator 10 needs to be electrically conductive and gas-impermeable, and in particular, must be free from the possibility that electrolyte phosphoric acid permeates into the through-holes to cause a liquid junction.

FIG. 3 is a configuration diagram showing an inspection apparatus used in a conventional inspection method for checking the gas permeability of the separator 10. As shown in FIG. As shown in the cross section in the drawing, the first manifold 11A is provided on one main surface of the separator 10 whose gas permeability is to be examined, and the second manifold 11A is provided on the other main surface.
B is hermetically incorporated by using a packing 15, and helium of a gas cylinder 13 is sent from the gas inlet 14 into the inside of the first manifold 11 </ b> A.
The gas flow meter 17 is connected to a pipe connected to the gas outlet 16 of the second manifold 11B, and the gas is passed through the separator 10 by the gas flow meter 17 so as to maintain the pressurized state. The amount of gas leaking to 11B is measured to determine gas permeability.

[0004]

In the conventional fuel cell, the amount of gas leaking through the separator 10 is measured by the method described above, and non-defective products are selected and used. However, since the separator 10 is formed of a thin carbon plate having a thickness of 1 mm or less, the amount of pressurized gas in the first manifold 11A needs to be suppressed to a range where the separator 10 is not broken by gas pressure. If the area of 10 is large, the amount of pressurization of the gas is limited to a low value, so that the amount of leakage is also small, and there is a problem that the detection accuracy is insufficient. Also, if there is a through hole in the separator, the electrolyte phosphoric acid penetrates into the through hole by capillary action,
There is a risk that the unit cells above and below the separator will liquid-junction and the power generation characteristics will be significantly reduced.In particular, detection of small-diameter through holes is required. Since the diameter is proportional to the fourth power of the diameter, a large diameter through hole can be easily detected. However, a small diameter through hole has a problem that it is difficult to detect even a large number of through holes.

[0005] The present invention has been made in view of such difficulties of the conventional method, and an object of the present invention is to prevent the possibility of breakage due to pressurization even in a large area, and to provide a liquid junction. It is an object of the present invention to provide a fuel cell separator inspection method capable of detecting gas permeation with high sensitivity even in a small-diameter through hole where there is a risk of occurrence.

[0006]

In order to achieve the above object, according to the present invention, there is provided a flat plate-shaped fuel cell which is inserted between a plurality of unit cells constituting a stacked fuel cell and used for gas separation. In the method for inspecting a separator, a first manifold is disposed on one main surface of the separator, a second manifold is disposed on the other main surface, and the first manifold is disposed on the first manifold.
Gas, for example, a gas such as helium or hydrogen, is filled under pressure, a second gas, for example, a gas such as nitrogen is passed through the second manifold, and the flow rate of the second gas and the discharge from the second manifold The concentration of the first gas in the gas to be measured is measured, and the gas permeability of the separator is examined.

According to the above, if there is a through hole in the separator, the first gas filled in the first manifold is diffused through the through hole due to a concentration difference, enters the second manifold, and enters the second manifold. 2 and discharged. As described above, the first gas is moved by the diffusion, so that the filling pressure of the first gas in the first manifold may be low, and the first gas does not depend on the diameter of the through hole. It can be easily detected.

[0008]

FIG. 1 is a block diagram showing an inspection apparatus used in an embodiment of the inspection method of the present invention for examining gas permeability of a separator. In the inspection device used in the present embodiment, the first manifold 1 similar to that used in the configuration of the conventional inspection method is provided on one main surface of the separator 10.
1A is provided, and the helium gas stored in the gas cylinder 13 is controlled and supplied by the pressure regulator 12. Further, on the other main surface of the separator 10, unlike the conventional one, a second manifold 11 </ b> C provided with a gas inlet 20 and a gas outlet 21 on opposite side surfaces is incorporated. Is connected to a gas supply port 22 for nitrogen gas by a pipe having a gas flow meter 23. In the middle of a discharge pipe connected to the gas discharge port 21, a branch connected to a gas analyzer 24 having a gas suction function is connected.

In the inspection method of the present embodiment, the inside of the first manifold 11A is filled with helium gas, and at the same time, the nitrogen gas is supplied from the gas inlet 20 into the inside of the second manifold 11C so that the main surface of the separator 10 Then, the gas is discharged from the gas outlet 21 and the flow rate of the nitrogen gas is measured by the gas flow meter 23, and the helium gas concentration in the discharged nitrogen gas is measured by the gas analyzer 24. ,
The amount of helium gas leaked from the first manifold 11A to the second manifold 11C is calculated to evaluate gas permeability.

In this embodiment, helium gas is used as a gas to fill the inside of the first manifold 11A. The helium gas is selected because of its short mean free path and excellent diffusivity. In this case, hydrogen having good diffusibility may be used instead of helium.
Further, although nitrogen is used as a gas flowing through the second manifold 11C, it is selected because nitrogen is chemically inert and there is no possibility of causing a chemical reaction with the gas diffused from the first manifold 11A side. It was done.

[0011]

As described above, according to the present invention, in a method of inspecting a flat separator used for gas separation inserted between a plurality of unit cells constituting a stacked fuel cell, A first manifold is arranged on one main surface, and a second manifold is arranged on the other main surface.
Is filled with a first gas, for example, a gas such as helium or hydrogen, under pressure, and a second gas, for example, a gas such as nitrogen is passed through the second manifold. Since the gas permeability of the separator is determined by measuring the concentration of the first gas in the gas discharged from the manifold 2, there is a possibility that the separator may be damaged by pressurization even if the separator has a large area. Thus, a method for inspecting a separator for a fuel cell, which can detect gas permeation with high sensitivity even in the case of a through hole having a small diameter and having a risk of liquid junction, can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an inspection apparatus used in an embodiment of an inspection method of the present invention for examining gas permeability of a separator.

FIG. 2 is an exploded perspective view of a main part showing a basic configuration of the stacked fuel cell.

FIG. 3 is a configuration diagram showing an inspection apparatus used in a conventional inspection method for examining gas permeability of a separator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Separator 11A 1st manifold 11C 2nd manifold 12 Pressure regulator 13 Gas cylinder 14 Gas inlet 15 Packing 20 Gas inlet 21 Gas outlet 22 Gas supply port 23 Gas flow meter 24 Gas analyzer

Claims (3)

[Claims] An inspection method of a flat separator used for gas separation inserted between a plurality of unit cells constituting a stacked type fuel cell, wherein a first manifold is provided on one main surface of the separator. A second manifold is arranged on the other main surface, the first manifold is filled with the first gas by pressurization, and the second gas is passed through the second manifold, and the flow rate of the second gas is increased. And the second
A method for inspecting a fuel cell separator, comprising: measuring a concentration of a first gas in a gas discharged from a manifold of (1) to check gas permeability. 2. The method for testing a fuel cell separator according to claim 1, wherein the first gas is helium or hydrogen. 3. The method for inspecting a fuel cell separator according to claim 1, wherein the second gas is nitrogen.