JP2004362915A - Solid polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the reliability of a solid polymer electrolyte fuel cell by preventing the deterioration of a solid polymer electrolyte membrane upon the interruption of an operation, in the solid polymer electrolyte fuel cell using an oxygen separation membrane. <P>SOLUTION: The deterioration of the solid polymer electrolyte membrane 1 is prevented by communicating with an inlet manifold 5 of fuel gas through the oxygen separation membrane 21 separating oxygen gas molecules from nitrogen gas molecules, making flow nitrogen gas on hydrogen side, and quickly exhausting hydrogen gas upon the interruption of the operation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid polymer electrolyte fuel cell.
[0002]
[Prior art]
Conventionally, this type of fuel cell has a power generation cell in which a gas diffusion electrode carrying a catalyst on both surfaces of a solid polymer electrolyte membrane provided with ionic conductivity is superposed on both surfaces. Then, a plurality of the power generation cells are connected to obtain a predetermined voltage. For this reason, a separator is interposed between the power generation cells, and the power generation cells are stacked and stacked. When the fuel gas and the oxidizing gas are supplied to both sides of the separator and the fuel gas and the oxidizing gas are supplied to the respective gas diffusion electrodes, the ionic conduction in the solid polymer electrolyte membrane and the chemical reaction of each gas diffusion electrode progress. As a result, a voltage is generated between the pair of gas diffusion electrodes, and power is supplied to an external circuit via a pair of separators at both ends having a function of a current collecting electrode. In such power generation, supplying the supplied gas to the electrode surface of the gas diffusion electrode as evenly as possible increases the gas utilization rate and improves power generation efficiency and output performance.
[0003]
Then, compared to the air (oxygen) on the oxidizing side of the fuel cell, the consumption of hydrogen on the fuel side of the fuel cell increases, and the pressure on the fuel side drops relatively greatly when the fuel cell system stops. In addition, there is a problem that a large pressure difference is generated between the fuel side and the oxidation side sandwiching the solid polymer electrolyte membrane, and the cell components of the fuel cell are deteriorated. Further, it is necessary to quickly discharge the hydrogen remaining on the fuel side at the time of stop. That is, if oxygen flows after the stoppage through the pipe or the solid polymer electrolyte membrane, a rapid oxidation reaction occurs, resulting in a high temperature or oxidative deterioration of the catalyst. In order to solve this problem, it is disclosed that when the fuel cell system is stopped, the reaction gas (mainly, hydrogen) in the fuel cell is replaced with an inert gas (for example, N2 or the like) or reacted air (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2004-122131). And Patent Document 1).
[0004]
In addition, the higher the concentration of hydrogen, which is the main component, in the reaction gas used in the fuel cell, the higher the power generation efficiency of the fuel cell can be improved. A system for supplying air to an air inlet of a stack humidifier is disclosed (for example, see Patent Document 2).
[0005]
[Patent Document 1]
JP-A-7-272740 [Patent Document 2]
JP 2000-260458 A
[Problems to be solved by the invention]
However, since the conventional fuel cell system (Patent Document 1) uses an inert gas cylinder such as nitrogen, it is necessary to check the remaining gas amount of the gas cylinder during operation and to replenish it when it runs out. However, there has been a problem that the fuel cell system becomes complicated and the cost increases. Also, in Patent Document 2, sufficient consideration has not been given to stopping the fuel cell system.
[0007]
[Means for Solving the Problems]
A solid polymer electrolyte fuel cell according to the present invention solves the above-mentioned conventional problems, and communicates an oxygen separation membrane for separating oxygen gas molecules and nitrogen gas molecules to a fuel gas inlet manifold via a fuel gas inlet pipe. It is configured.
[0008]
Thus, when the operation is stopped, the nitrogen gas is caused to flow to the hydrogen side and the hydrogen gas is quickly discharged, thereby preventing the deterioration of the solid polymer electrolyte membrane and improving the reliability of the solid polymer electrolyte fuel cell. Can be provided.
[0009]
That is, when the operation of the polymer electrolyte fuel cell is stopped, the supply of hydrogen gas as the fuel gas is stopped, and then the fuel cell is connected to the fuel gas inlet manifold through the oxygen separation membrane for separating oxygen gas molecules and nitrogen gas molecules. As a result, oxygen gas molecules are removed from the air, that is, nitrogen gas molecules are supplied to the fuel side of the fuel cell, and hydrogen gas is expelled and replaced with nitrogen gas. For this reason, after the operation of the solid polymer electrolyte fuel cell is stopped, hydrogen gas remains in the fuel cell, and reacts with oxygen on the cathode side by diffusion to the cathode side, and when air is mixed into the anode side when stopped, A solid polymer electrolyte fuel cell with improved reliability by preventing high temperature due to combustion and deterioration of the catalyst can be obtained.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention according to claim 1 is characterized in that a pair of gas diffusion electrodes sandwiching the solid polymer electrolyte membrane, and a flow channel for guiding the fuel gas and the oxidizing gas from the respective inlet manifolds to the outlet manifolds on each surface of the gas diffusion electrodes. An oxygen separation membrane for separating oxygen gas molecules and nitrogen gas molecules from the formed separator is connected to a fuel gas inlet manifold via a fuel gas inlet pipe.
[0011]
Thus, when the operation is stopped, the nitrogen gas is caused to flow to the hydrogen side and the hydrogen gas is quickly discharged, thereby preventing the deterioration of the solid polymer electrolyte membrane and improving the reliability of the solid polymer electrolyte fuel cell. Can be provided.
[0012]
In other words, when the temperature of the solid polymer electrolyte membrane becomes high, the electrical conversion rate decreases and the reliability deteriorates due to material deterioration.To prevent this, air and water are flowed during operation to cool the membrane. Cooling stops.
[0013]
In addition, when oxygen gas and hydrogen gas are present, the combustion reaction is promoted near the catalyst, and the catalyst performance deteriorates due to a rapid temperature rise. Therefore, when the operation of the solid polymer electrolyte fuel cell is stopped, the supply of hydrogen gas as a fuel gas is stopped, and an oxygen separation membrane for separating oxygen gas molecules and nitrogen gas molecules is connected to the fuel gas through a fuel gas inlet pipe. The oxygen gas molecules are removed from the air, that is, the nitrogen gas molecules are supplied to the fuel side of the fuel cell, and the hydrogen gas can be expelled and replaced by the nitrogen gas. For this reason, after the operation of the solid polymer electrolyte fuel cell is stopped, hydrogen gas remains in the fuel cell, and reacts with oxygen on the cathode side by diffusion to the cathode side, and when air is mixed into the anode side when stopped, A solid polymer electrolyte fuel cell with improved reliability by preventing high temperature due to combustion and deterioration of the catalyst can be obtained.
[0014]
The second aspect of the present invention provides a solid polymer electrolyte fuel cell in which an on-off valve is provided in the fuel gas inlet pipe between the oxygen separation membrane and the fuel gas inlet manifold. Can be replaced, and the reliability can be improved. That is, during operation of the fuel cell, the on-off valve is closed, and only hydrogen gas is flowed to the anode side to maintain high efficiency operation of the fuel cell. Next, when the fuel cell is stopped, the on-off valve is opened to stop the supply of hydrogen gas as a fuel gas, and then to the fuel gas inlet manifold through an oxygen separation membrane for separating oxygen gas molecules and nitrogen gas molecules. By opening the communicating on-off valve, oxygen gas molecules are removed from the air, that is, nitrogen gas molecules are quickly supplied to the fuel side of the fuel cell, and hydrogen gas is expelled and replaced with nitrogen gas. For this reason, the gas can be reliably replaced, and a solid polymer electrolyte fuel cell having high reliability by reliably preventing high temperature due to combustion and deterioration of the catalyst can be obtained.
[0015]
The invention according to claim 3 is particularly directed to the solid polymer electrolyte fuel cell according to claims 1 and 2, wherein one of the oxygen separation membranes is depressurized by a blower to discharge air having an increased oxygen concentration, and the other of the oxygen separation membranes is discharged. The oxygen-enriched air communicates with the fuel gas inlet manifold, allowing the oxygen separation membrane to supply high-concentration nitrogen gas to the anode side of the fuel cell when it is stopped. And reliability can be improved.
[0016]
That is, the oxygen separation membrane utilizes the fact that the rate of dissolution / diffusion differs depending on the gas species when there is a pressure difference. When a pressure difference is provided between the two surfaces of the oxygen separation membrane, the oxygen separation membrane operates on the principle that oxygen on the atmosphere side dissolves on the membrane surface, diffuses in the membrane, and separates from the membrane surface on the reduced pressure side. For this reason, one side of the oxygen separation membrane is decompressed by a blower to discharge air having a high oxygen concentration, and the other air having a sufficiently high nitrogen concentration is discharged from the oxygen separation membrane through a fuel gas inlet pipe. When the fuel cell is stopped, hydrogen gas on the fuel side of the fuel cell can be expelled and replaced with nitrogen gas when the fuel cell is stopped. For this reason, the gas can be stably and reliably replaced, and a solid polymer electrolyte fuel cell having high reliability by reliably preventing high temperature due to combustion and deterioration of the catalyst can be obtained.
[0017]
According to the fourth aspect of the present invention, in particular, one of the oxygen separation membranes of the solid polymer electrolyte fuel cells according to the first to third aspects is decompressed by a blower to oxidize air having an increased oxygen concentration through an oxidizing gas inlet pipe. By communicating with the gas inlet manifold, the replacement of gas on the fuel side of the fuel cell prevents high temperature and catalyst deterioration, thereby improving reliability and increasing the oxygen partial pressure on the cathode side of the fuel cell. It is possible to increase the efficiency of the battery.
[0018]
That is, one of the oxygen separation membranes was depressurized by a blower to discharge air having an increased oxygen concentration, and the other of the oxygen separation membranes having an increased nitrogen concentration was communicated with the fuel gas inlet manifold. Thereby, when the fuel cell is stopped, the hydrogen gas on the fuel side of the fuel cell can be expelled and replaced with the nitrogen gas with almost high concentration nitrogen gas of nitrogen. For this reason, the gas can be stably and reliably replaced, and a solid polymer electrolyte fuel cell having high reliability by reliably preventing high temperature due to combustion and deterioration of the catalyst can be obtained. Then, air having an increased oxygen concentration by reducing the pressure of one of the oxygen separation membranes by a blower is communicated to the oxidizing gas inlet manifold, whereby the oxygen partial pressure on the cathode side is increased. The power generation efficiency of the fuel cell is determined by the proton conductivity of the solid polymer membrane, and this proton conductivity affects the gas partial pressure of each of the anode and cathode gases. By using air on the cathode side and supplying air having an oxygen concentration higher than the oxygen concentration of 20.8% to the cathode, the power generation efficiency of the fuel cell increases. For this reason, the efficiency of the fuel cell can be increased, and when the same power generation efficiency is set, the size of the fuel cell can be reduced, so that the size and cost can be reduced, and the use performance can be improved.
[0019]
In the invention according to claim 5, the solid polymer electrolyte fuel cells according to claims 1 to 4 are provided with a plurality of oxygen separation membranes and arranged in series, so that the oxygen separation membrane allows air to be mixed with oxygen gas at a higher concentration. Nitrogen gas can be separated, and the replacement of the gas on the fuel side of the fuel cell can completely prevent high temperature and catalyst deterioration, thereby improving reliability and increasing the oxygen partial pressure on the cathode side of the fuel cell. Further higher efficiency can be achieved.
[0020]
That is, the oxygen separation membrane utilizes the fact that the rate of dissolution / diffusion differs depending on the gas species when there is a pressure difference. When a pressure difference is provided between the two surfaces of the oxygen separation membrane, the oxygen separation membrane operates on the principle that oxygen on the atmosphere side dissolves on the membrane surface, diffuses in the membrane, and separates from the membrane surface on the reduced pressure side. For this reason, at a constant pressure difference, the concentration of the gas to be separated is determined according to the area. Therefore, by providing a plurality of oxygen separation membranes and arranging them in series, the separation can be performed remarkably sequentially, and even if the pressure difference is not increased and the area is not increased, the oxygen separation efficiency is further improved, and It can be separated into gas. For this reason, a plurality of oxygen separation membranes are provided and arranged in series, so that high-concentration oxygen gas is supplied to the cathode side and high-concentration nitrogen gas flows to the anode side during shutdown to replace hydrogen gas. As a result, the gas can be stably and reliably replaced, and a solid polymer electrolyte fuel cell having high reliability by reliably preventing a high temperature due to combustion and deterioration of the catalyst can be obtained. The power generation efficiency of the fuel cell is increased by supplying the cathode with air having further increased oxygen concentration on the cathode side. For this reason, it is possible to further increase the efficiency of the fuel cell, and in the case of setting the same power generation efficiency, it is possible to reduce the size of the fuel cell, further reduce the size and cost, and improve the use performance.
[0021]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
(Example 1)
FIG. 1 is an overall configuration diagram of a solid polymer electrolyte fuel cell according to a first embodiment of the present invention, FIG. 2 is a configuration diagram of a fuel cell separator, and FIG. 3 is a sectional view of a power generation cell of the fuel cell. In FIG. 3, a solid polymer electrolyte fuel cell constitutes a power generation cell by stacking gas diffusion electrodes 12 carrying a catalyst on both surfaces of a solid polymer electrolyte membrane 11 provided with ion conductivity on both surfaces. . Then, a plurality of the power generation cells are connected to obtain a predetermined voltage. For this reason, the separators 1 are interposed between the power generation cells, and the power generation cells are stacked and stacked. When the fuel gas and the oxidizing gas are supplied to both sides of the separator and the fuel gas and the oxidizing gas are supplied to the respective gas diffusion electrodes 12, the ionic conduction in the solid polymer electrolyte membrane 11 and the electrochemical As the reaction proceeds, a voltage is generated between the pair of gas diffusion electrodes 12, and power is supplied to an external circuit (not shown) via the pair of separators 1 on both ends having a function of a current collecting electrode. In such power generation, supplying the supplied gas to the electrode surface of the gas diffusion electrode 12 as evenly as possible increases the gas utilization rate and improves the power generation efficiency and output performance.
[0023]
In the separator 1 shown in FIG. 2, the flow channel 2 of the separator 1 has a shape corresponding to the gas diffusion electrode 12 and is made of carbon having gas impermeability and conductivity, surface-treated metal, or the like. Fuel or oxidizing gas flows from the inlet manifold 3, and flows out of the outlet manifold 4 through the gas of the flow channel 2. On the other hand, the oxidizing gas or fuel gas separator 1 is provided with a similar flow structure on the back side of the separator 1, and gas is introduced and discharged from the inlet manifold 5 and the output manifold 6. Thereby, the separator 1 is formed in which the flow grooves 2 for guiding the fuel gas and the oxidizing gas from the respective inlet sides to the respective outlet sides are formed on the respective surfaces of the pair of gas diffusion electrodes 12 sandwiching the solid polymer electrolyte membrane 11. are doing.
[0024]
In the solid polymer electrolyte fuel cell shown in FIG. 1, the stacked power generation cell 13 generates electric power by superposing the gas diffusion electrodes 12 supporting the catalyst on both surfaces of the solid polymer electrolyte membrane 11 shown in FIG. The power generation cells are stacked to form a stack with a separator 1 interposed between the cells, and are fastened by end plates 14. (Electric power extraction electrodes and circuits are not shown.) The oxidizing gas is connected to the inlet manifold 3 by an oxidizing gas inlet pipe 15 connected to a filter, a humidity adjusting unit, and the like, and the oxidizing gas outlet pipe 16 is connected to the outlet manifold 4. It is connected to an oxidizing gas blower 17. The fuel gas is connected to the inlet manifold 5 by a fuel gas inlet pipe 18 connected to a fuel tank, a reformer, a humidity control unit, and the like, and the fuel gas is connected to the outlet manifold 6 to a fuel gas blower 20 by a fuel gas outlet pipe 19. I have. The fuel gas is connected to a fuel gas inlet pipe 18 communicating with the fuel gas inlet manifold 5 through an oxygen separation membrane 21 for separating oxygen gas molecules and nitrogen gas molecules through an on-off valve 22. Also. The other side of the oxygen separation membrane 21 is open to the outside air via an exhaust fan 23.
[0025]
The operation and action of the solid polymer electrolyte fuel cell using the oxygen separation membrane configured as described above will be described below.
[0026]
The oxidizing gas is adjusted by a filter, a humidity adjusting unit, and the like by operating the oxidizing gas blower 17, and then enters from the oxidizing gas inlet pipe 15 through the inlet manifold 3 of the stacked power generation cell 13 and passes through the flow channel 2 of the separator 1. After flowing, it flows from the outlet manifold 4 through the oxidizing gas outlet pipe 16 to the outside from the oxidizing gas blower 17. At the same time, by operating the fuel gas blower 20, the fuel gas flows from the fuel tank, the reformer, the humidity control unit, etc., through the fuel gas inlet pipe 18, flows from the inlet manifold 5 of the stacked power generation cell 13, and flows into the separator 1. After flowing through the channel 2, the fuel gas is discharged from the outlet manifold 6 to the outside through the fuel gas outlet pipe 19 through the fuel gas blower 20. The released oxidizing gas and fuel gas may be connected to a heat exchanger, a humidifying exchanger and the like, and the heat, humidity, undecomposed gas and the like may be reused. When the fuel gas flows through the flow channel 2, the fuel gas diffuses into the gas diffusion electrode to perform an electrochemical reaction, becomes water, and is discharged to the outlet manifold 4 while sequentially reducing the mass.
[0027]
Since the fuel cell is connected to the fuel gas inlet manifold 5 through an oxygen separation membrane 21 for separating oxygen gas molecules and nitrogen gas molecules, when the operation is stopped, the nitrogen gas is caused to flow to the hydrogen side and the hydrogen gas By promptly discharging the solid polymer electrolyte membrane, it is possible to provide a solid polymer electrolyte fuel cell in which the deterioration of the polymer electrolyte membrane 11 is prevented and the reliability is improved.
[0028]
That is, when the temperature of the solid polymer electrolyte membrane 11 becomes high, the electrical conversion rate decreases and the reliability deteriorates due to material deterioration. To prevent this, air or water is flown during operation to cool the solid polymer electrolyte membrane 11. At the same time, cooling stops. In addition, when oxygen gas and hydrogen gas are present, the combustion reaction is promoted near the catalyst, and the catalyst performance deteriorates due to a rapid temperature rise. Therefore, when the operation of the solid polymer electrolyte fuel cell is stopped, the supply of hydrogen gas as the fuel gas is stopped, and then the fuel gas inlet manifold 5 through the oxygen separation membrane 21 for separating oxygen gas molecules and nitrogen gas molecules. , The oxygen gas molecules are removed from the air, that is, the nitrogen gas molecules are supplied to the fuel side of the fuel cell, and the hydrogen gas is expelled and replaced with the nitrogen gas. For this reason, after the operation of the solid polymer electrolyte fuel cell is stopped, hydrogen gas remains in the fuel cell, and reacts with oxygen on the cathode side by diffusion to the cathode side, and when air is mixed into the anode side when stopped, A solid polymer electrolyte fuel cell with improved reliability by preventing high temperature due to combustion and deterioration of the catalyst can be obtained.
[0029]
In addition, since the on-off valve 22 is provided in the middle of the communication path between the oxygen separation membrane 21 and the fuel gas inlet manifold 5, the gas can be reliably replaced, and the reliability can be improved. That is, during the operation of the fuel cell, the on-off valve 22 is closed, and only the hydrogen gas flows to the anode side, so that the fuel cell operates at high efficiency. Next, when the fuel cell is stopped, the on-off valve 22 is opened to stop the supply of the hydrogen gas as the fuel gas, and then the fuel gas inlet through the oxygen separation membrane 21 for separating oxygen gas molecules and nitrogen gas molecules. By opening the on-off valve 22 connected to the manifold 5, the oxygen gas molecules are removed from the air, that is, the nitrogen gas molecules are quickly supplied to the fuel side of the fuel cell, and the hydrogen gas is expelled and replaced with the nitrogen gas. For this reason, the gas can be reliably replaced, and a solid polymer electrolyte fuel cell having high reliability by reliably preventing high temperature due to combustion and deterioration of the catalyst can be obtained.
[0030]
Further, one of the oxygen separation membranes 21 is decompressed by the blower 23 to discharge air having an increased oxygen concentration, and the other of the oxygen separation membranes 21 is communicated with the air having an increased nitrogen concentration to the fuel gas inlet manifold 5. As a result, since the other side of the oxygen separation membrane 21 is open to the outside air via the exhaust fan 23, when the exhaust fan 23 is operated, the air sucked in from the air inlet 24 converts oxygen into oxygen by the oxygen separation membrane 21. The exhaust gas is exhausted to the outside air from the exhaust fan 23 as a gas containing much. Therefore, the air stored in the portion of the oxygen separation membrane 21 communicating with the on-off valve 22 gradually increases in nitrogen ratio, and after a while, becomes almost nitrogen gas.
[0031]
Therefore, a high-concentration nitrogen gas can be supplied to the anode side of the fuel cell when the fuel cell is stopped by the oxygen separation membrane 21, so that the gas can be replaced stably and surely, and the reliability can be improved.
[0032]
That is, the oxygen separation membrane 21 utilizes the fact that when there is a pressure difference, the rate of dissolution / diffusion differs depending on the type of gas. When a pressure difference is provided between both surfaces of the oxygen separation membrane 21, the operation is performed on the principle that oxygen on the atmosphere side dissolves on the membrane surface, diffuses inside the membrane, and separates from the membrane surface on the reduced pressure side. For this reason, one of the oxygen separation membranes 21 is depressurized by the blower 23 to discharge the air having an increased oxygen concentration, and the other of the oxygen separation membranes 21 having the sufficiently increased nitrogen concentration is supplied to the fuel gas inlet manifold 5. When the fuel cell is stopped, the hydrogen gas on the fuel side of the fuel cell can be expelled and replaced with the nitrogen gas when the fuel cell is stopped. For this reason, the gas can be stably and reliably replaced, and a solid polymer electrolyte fuel cell having high reliability by reliably preventing high temperature due to combustion and deterioration of the catalyst can be obtained.
[0033]
(Example 2)
FIG. 4 is an overall configuration diagram of a solid polymer electrolyte fuel cell according to a second embodiment of the present invention. The difference from the first embodiment is that one of the oxygen separation membranes 21 is depressurized by a blower 23 and the oxygen-enriched air is communicated with the oxidizing gas inlet manifold 3 so that the gas on the fuel side of the fuel cell can be removed. The substitution prevents the temperature from rising and the catalyst from deteriorating, thereby increasing the reliability. In addition, the oxygen partial pressure on the cathode side of the fuel cell can be increased, and the efficiency of the fuel cell can be increased.
[0034]
That is, one of the oxygen separation membranes 21 is decompressed by the blower 23 to discharge air having an increased oxygen concentration, and the other of the oxygen separation membranes 21 having the sufficiently increased nitrogen concentration is supplied to the fuel gas inlet manifold 3. With the communication, when the fuel cell is stopped, hydrogen gas on the fuel side of the fuel cell can be expelled and replaced with nitrogen gas with almost high concentration nitrogen gas. For this reason, the gas can be stably and reliably replaced, and a solid polymer electrolyte fuel cell having high reliability by reliably preventing high temperature due to combustion and deterioration of the catalyst can be obtained. Then, the air having an increased oxygen concentration by reducing the pressure of one of the oxygen separation membranes 21 by the blower 23 is communicated to the oxidizing gas inlet manifold 3 to increase the oxygen partial pressure on the cathode side. The power generation efficiency of the fuel cell is determined by the proton conductivity of the polymer electrolyte membrane 11, and this proton conductivity affects the gas partial pressure of each of the anode and cathode gases. By using air on the cathode side and supplying air having an oxygen concentration higher than the oxygen concentration of 20.8% to the cathode, the power generation efficiency of the fuel cell increases. For this reason, the efficiency of the fuel cell can be increased, and when the same power generation efficiency is set, the size of the fuel cell can be reduced, so that the size and cost can be reduced, and the use performance can be improved.
[0035]
(Example 3)
FIG. 5 is a partial configuration diagram of a solid polymer electrolyte fuel cell according to a third embodiment of the present invention. The difference from the first embodiment is that a plurality of oxygen separation membranes 21 are provided and arranged in series. In this embodiment, three oxygen separation membranes 21 (a), 21 (b) and 21 (c) are arranged in series. As a result, air can be separated into oxygen gas and nitrogen gas at a higher concentration by the oxygen separation membranes 21 (a), 21 (b), and 21 (c), and the temperature of the fuel cell can be increased by replacing the gas on the fuel side. The catalyst can be completely prevented from being deteriorated to improve reliability, and the oxygen partial pressure on the cathode side of the fuel cell can be further increased, so that the efficiency of the fuel cell can be further improved.
[0036]
That is, the oxygen separation membranes 21 (a), 21 (b), and 21 (c) utilize the fact that the rate of dissolution / diffusion differs depending on the type of gas when there is a pressure difference. If a pressure difference is provided between both surfaces of the oxygen separation membranes 21 (a), 21 (b), and 21 (c), oxygen on the atmospheric side dissolves on the membrane surface, diffuses in the membrane, and separates from the membrane surface on the reduced pressure side. Works on the principle. For this reason, at a constant pressure difference, the concentration of the gas to be separated is determined according to the area. Therefore, by providing a plurality of oxygen separation membranes 21 (a), 21 (b) and 21 (c) and arranging them in series, the separation can be performed remarkably sequentially, without increasing the pressure difference and increasing the area. However, the oxygen separation efficiency is further improved, and the gas can be separated into high concentration gas. For this reason, a plurality of oxygen separation membranes 21 (a), 21 (b), 21 (c) are provided and arranged in series, so that a high-concentration oxygen gas is supplied to the cathode side, and to the anode side during shutdown. High-concentration nitrogen gas allows the replacement of hydrogen gas, enabling stable and reliable gas replacement, and reliably preventing high temperature and deterioration of the catalyst due to combustion, thereby improving reliability. An electrolyte fuel cell can be obtained. The power generation efficiency of the fuel cell is increased by supplying the cathode with air having further increased oxygen concentration on the cathode side. For this reason, it is possible to further increase the efficiency of the fuel cell, and in the case of setting the same power generation efficiency, it is possible to reduce the size of the fuel cell, further reduce the size and cost, and improve the use performance.
[0037]
【The invention's effect】
As described above, according to the present invention, by communicating with the fuel gas inlet manifold through the oxygen separation membrane that separates oxygen gas molecules and nitrogen gas molecules, this nitrogen gas is shut down during operation. By flowing the hydrogen gas to the hydrogen side and quickly discharging the hydrogen gas, it is possible to provide a solid polymer electrolyte fuel cell in which the deterioration of the polymer electrolyte membrane is prevented and the reliability is improved.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing a solid polymer electrolyte fuel cell according to a first embodiment of the present invention; FIG. 2 is a configuration diagram of a separator of the solid polymer electrolyte fuel cell according to the first embodiment of the present invention; FIG. 3 is a cross-sectional view of a power generation cell of a solid polymer electrolyte fuel cell according to a first embodiment of the present invention. FIG. 4 is an overall configuration diagram of a solid polymer electrolyte fuel cell according to a second embodiment of the present invention. FIG. 5 is a partial configuration diagram of a solid polymer electrolyte fuel cell according to a third embodiment of the present invention.
1 Separator 3 Inlet manifold (oxidizing gas)
4 Outlet manifold (oxidizing gas)
5 Inlet manifold (fuel gas)
6. Exit manifold (fuel gas)
DESCRIPTION OF SYMBOLS 11 Solid polymer electrolyte membrane 12 Gas diffusion electrode 15 Oxidizing gas inlet pipe 18 Fuel gas inlet pipe 21 Oxygen separation membrane 22 On-off valve 23 Blower

Claims (5)

A pair of gas diffusion electrodes sandwiching the solid polymer electrolyte membrane, and a separator having a flow channel formed on each surface of the gas diffusion electrodes to guide the fuel gas and the oxidizing gas from the respective inlet manifold to the outlet manifold, A solid polymer electrolyte fuel cell, wherein an oxygen separation membrane for separating oxygen gas molecules and nitrogen gas molecules communicates with the fuel gas inlet manifold via a fuel gas inlet pipe. 2. The solid polymer electrolyte fuel cell according to claim 1, wherein an on-off valve is provided in the fuel gas inlet pipe between the oxygen separation membrane and the fuel gas inlet manifold. One of the oxygen separation membranes is decompressed by a blower to discharge air having an increased oxygen concentration, and the other of the oxygen separation membranes having an increased nitrogen concentration is supplied to a fuel gas inlet manifold via a fuel gas inlet pipe. 3. The solid polymer electrolyte fuel cell according to claim 1, wherein the fuel cells are connected to each other. 4. The solid polymer according to claim 1, wherein one of the oxygen separation membranes is decompressed by a blower, and the air having an increased oxygen concentration is communicated to an oxidizing gas inlet manifold through an oxidizing gas inlet pipe. Electrolyte fuel cell. 5. The solid polymer electrolyte fuel cell according to claim 1, wherein a plurality of oxygen separation membranes are provided and arranged in series.

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