JP2005116375A - FUEL CELL OPERATION DEVICE, FUEL CELL OPERATION METHOD, PROGRAM, AND RECORDING MEDIUM - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deteriorate the durability of a fuel cell due to catalyst deterioration during long-term storage.
In a storage period of a fuel cell, (a) oxygen content in a portion between a gate valve 41 provided upstream from an oxidant electrode and a gate valve 42 provided downstream from an oxidant electrode. Detection of gas flow path oxygen concentration and / or (b) fuel gas flow path in a portion between a gate valve 37 provided upstream from the fuel electrode and a gate valve 43 provided downstream from the fuel electrode When the oxygen concentration detectors 50 and 51 for detecting the oxygen concentration and the detected oxygen-containing gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration are equal to or higher than a predetermined value, (a) partition A control unit that injects a predetermined purge gas into a portion between the valve 41 and the gate valve 42 and / or (b) injects a predetermined purge gas into a portion between the gate valve 37 and the gate valve 43. 45, fuel cell power generation Device.
[Selection] Figure 3

Description

  The present invention relates to a fuel cell operating device, a fuel cell operating method, a program, and a recording medium.

  A general structure of a conventional fuel cell will be described using a polymer electrolyte fuel cell.

  A fuel cell obtains electric energy and heat energy mainly from hydrogen and oxygen.

Due to the catalytic action of Pt and the like,
H ₂ → 2H ⁺ + 2e ⁻
The reaction shown below occurs, and on the oxidant electrode side (Chemical Formula 2)
^{_{O 2/2 + 2H + →}} H 2 O
The reaction represented by

The total reaction is
_{H 2 + O 2/2 →} H 2 O
It is represented by

  In order to prevent deterioration due to carbon monoxide or the like on the fuel electrode side, a mixture or alloy with Ru is used in addition to Pt. By these actions, the fuel cell reacts with hydrogen and oxygen, and only water is produced as a reaction product. A major feature is that no substances that affect the environment are discharged.

  However, since it is not necessary to move until the time when electricity or heat energy is not needed, there is a need for a “start / stop type” operation that starts when necessary and stops when not needed.

  Several methods have been considered as methods of starting and stopping.

  When stopping, there are a method of stopping supply of oxygen-containing gas and fuel gas and leaving it as it is, a method of purging only the oxidant electrode, and a method of purging only the fuel electrode.

  In addition, a method for stopping and storing a humidified inert gas or water in order to maintain the water retention state of the ion exchange membrane, which is an electrolyte, during storage is disclosed (for example, see Patent Document 1).

Moreover, in order to prevent oxidation of the oxidant electrode or adhesion of impurities when the operation is stopped, a method of generating power with the supply of oxygen-containing gas stopped and performing oxygen consumption operation to improve durability is shown ( For example, see Patent Document 2).
JP-A-6-251788 JP 2002-93448 A

  However, the method of stopping and storing while holding the fuel gas has a safety problem, and the method of stopping and storing while holding the oxygen-containing gas is problematic in that the performance decreases due to catalytic oxidation by oxygen and the catalytic function decreases due to potential. It is. For example, at the time of stoppage, the potential reaches a high potential of 0.9 V at the oxidizer electrode, elution and sintering of the Pt catalyst occurs, and the potential reaches 0.68 V or more at the fuel electrode and Ru elution occurs. Decreases.

  Further, in the stopped storage method in which both electrodes are purged with an inert gas or the like, the potential difference between both electrodes becomes zero, but the potentials of both electrodes take various values depending on the stopping method. For example, when the fuel electrode is purged and then the oxidant electrode is purged, the potential difference between the two electrodes is zero, and the potential shows a high potential close to 0.9V. On the other hand, when the fuel electrode is purged after purging the oxidant electrode, the potential difference between the two electrodes is zero and the potential is close to 0V.

  The inventor has realized that the potentials of both electrodes change not only when stopped but also during storage.

  The stopped storage period of the fuel cell power generation device may be several hours to several days, or months. For this reason, the potentials of both electrodes may change due to a small amount of gas leakage after the electrodes are stored at a certain potential at zero potential difference.

  In view of the above-described conventional problems, the present invention makes it difficult to cause catalyst deterioration even during long-term storage, and can further improve the durability of the fuel cell, a fuel cell operating device, a fuel cell operating method, It is an object to provide a program and a recording medium.

According to the first aspect of the present invention, during the storage period of the fuel cell, (1) the oxygen-containing gas flow path for supplying and discharging a predetermined oxygen-containing gas to and from the oxidant electrode of the fuel cell An oxygen-containing gas flow path upstream valve provided upstream and an oxygen-containing gas flow path in a portion between the oxygen-containing gas flow path and the oxygen-containing gas flow path downstream valve provided downstream of the oxidant electrode. On the fuel gas flow path provided upstream of the fuel electrode in the fuel gas flow path for detecting the road oxygen concentration and / or (2) supplying and discharging a predetermined fuel gas to the fuel electrode of the fuel cell An oxygen concentration detection means for detecting a fuel gas flow path oxygen concentration in a portion between the flow valve and the fuel gas flow path downstream valve provided downstream of the fuel electrode in the fuel gas supply flow path;
When the detected oxygen-containing gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration is a predetermined value or more, (a) the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow Injection of a predetermined purge gas into a portion between the downstream valve and / or (b) a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve A fuel cell operating device comprising a purge gas injection means for performing injection.

The second aspect of the present invention further includes fuel gas cleaning means for cleaning the predetermined fuel gas,
The predetermined purge gas is the fuel cell operating device according to the first aspect of the present invention, which is the purified fuel gas.

  The third aspect of the present invention is the fuel cell operating device according to the first aspect of the present invention, wherein the predetermined value is 10 ppm.

According to a fourth aspect of the present invention, in the storage period of the fuel cell, (1) the oxygen-containing gas flow path for supplying and discharging a predetermined oxygen-containing gas to and from the oxidant electrode of the fuel cell An oxygen-containing gas flow path upstream valve provided upstream and an oxygen-containing gas flow path in a portion between the oxygen-containing gas flow path and the oxygen-containing gas flow path downstream valve provided downstream of the oxidant electrode. On the fuel gas flow path provided upstream of the fuel electrode in the fuel gas flow path for detecting the road oxygen concentration and / or (2) supplying and discharging a predetermined fuel gas to the fuel electrode of the fuel cell An oxygen concentration detection step of detecting a fuel gas flow path oxygen concentration in a portion between the flow valve and a fuel gas flow path downstream valve provided downstream of the fuel electrode in the fuel gas supply flow path;
When the detected oxygen-containing gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration is a predetermined value or more, (a) the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow Injection of a predetermined purge gas into a portion between the downstream valve and / or (b) a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve A fuel cell operation method comprising a purge gas injection step for performing injection.

  According to a fifth aspect of the present invention, when the detected oxygen-containing gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration is equal to or greater than a predetermined value in the fuel cell operating method according to claim 4. (A) injection of a predetermined purge gas into a portion between the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow path downstream valve, and / or (b) the fuel gas flow path upstream valve and the This is a program for causing a computer to execute a purge gas injection step for injecting a predetermined purge gas into a portion between the fuel gas flow path downstream valve and the fuel gas flow path downstream valve.

According to a sixth aspect of the present invention, during the storage period of the fuel cell, (1) the oxygen-containing gas flow path for supplying and discharging a predetermined oxygen-containing gas to and from the oxidant electrode of the fuel cell A predetermined purge for a portion between an oxygen-containing gas channel upstream valve provided upstream and an oxygen-containing gas channel downstream valve provided downstream of the oxidant electrode in the oxygen-containing gas channel Injection of gas, or (2) a fuel gas flow path upstream valve provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to and from the fuel electrode of the fuel cell; A first purge gas injection means for injecting a predetermined purge gas into a portion between the fuel gas supply flow path and a fuel gas flow path downstream valve provided downstream of the fuel electrode;
A potential difference detecting means for detecting a potential difference between the potential of the oxidant electrode and the potential of the fuel electrode;
Injection of a predetermined purge gas into a portion between the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow path downstream valve, or between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve When the change in the detected potential difference before and after the injection of the predetermined purge gas to the portion is greater than or equal to a predetermined value, (a) the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow Injection of a predetermined purge gas into the portion between the downstream valve and (b) injection of a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve. It is a fuel cell operating device provided with the 2nd purge gas injection means performed again.

The seventh aspect of the present invention further includes a fuel gas cleaning means for cleaning the predetermined fuel gas,
The predetermined purge gas is the fuel cell operating device according to the sixth aspect of the present invention, which is the purified fuel gas.

  An eighth aspect of the present invention is the fuel cell operating device according to the sixth aspect of the present invention, wherein the predetermined value is 10 mV.

According to a ninth aspect of the present invention, in the storage period of the fuel cell, (1) the oxygen-containing gas flow path for supplying and discharging a predetermined oxygen-containing gas to and from the oxidant electrode of the fuel cell A predetermined purge for a portion between an oxygen-containing gas channel upstream valve provided upstream and an oxygen-containing gas channel downstream valve provided downstream of the oxidant electrode in the oxygen-containing gas channel Injection of gas, or (2) a fuel gas flow path upstream valve provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to and from the fuel electrode of the fuel cell; A first purge gas injection step for injecting a predetermined purge gas into a portion between the fuel gas supply channel and a fuel gas channel downstream valve provided downstream of the fuel electrode;
A potential difference detection step for detecting a potential difference between the potential of the oxidant electrode and the potential of the fuel electrode;
Injection of a predetermined purge gas into a portion between the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow path downstream valve, or between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve When the change in the detected potential difference before and after the injection of the predetermined purge gas to the portion is greater than or equal to a predetermined value, (a) the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow Injection of a predetermined purge gas into the portion between the downstream valve and (b) injection of a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve. And a second purge gas injection step that is performed again.

  According to a tenth aspect of the present invention, in the fuel cell operating method of the ninth aspect of the present invention, during the storage period of the fuel cell, (1) a predetermined oxygen-containing gas is supplied to the oxidant electrode of the fuel cell and discharged. An oxygen-containing gas flow path upstream valve provided upstream of the oxidant electrode in the oxygen-containing gas flow path, and an oxygen-containing gas flow provided downstream of the oxidant electrode in the oxygen-containing gas flow path Injection of a predetermined purge gas into the portion between the downstream valve and (2) supply and discharge of a predetermined fuel gas to and from the fuel electrode of the fuel cell in the fuel gas flow path than the fuel electrode A predetermined purge gas is injected into a portion between a fuel gas flow path upstream valve provided upstream and a fuel gas flow path downstream valve provided downstream of the fuel electrode in the fuel gas supply flow path. First purge gas to perform An injection step, injection of a predetermined purge gas into a portion between the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow path downstream valve, or the fuel gas flow path upstream valve and the fuel gas flow path downstream When the change in the detected potential difference before and after the injection of the predetermined purge gas to the portion between the valve and the valve is greater than or equal to a predetermined value, (a) the oxygen-containing gas flow path upstream valve and the Injection of a predetermined purge gas to a portion between the oxygen-containing gas flow path downstream valve and (b) a predetermined purge for a portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve This is a program for causing a computer to execute a second purge gas injection step for performing gas injection again.

  The eleventh aspect of the present invention is a recording medium carrying the program of the fifth or tenth aspect of the present invention, and is a recording medium that can be processed by a computer.

  The present invention has an advantage that catalyst deterioration hardly occurs even during long-term storage, and the durability of the fuel cell can be further improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
First, the configuration of the fuel cell power generator according to the present embodiment will be described with reference mainly to FIGS.

  FIG. 1 shows a basic configuration of a polymer electrolyte fuel cell (hereinafter referred to as PEFC) among the fuel cells according to Embodiment 1 of the present invention.

  A fuel cell is one that causes a fuel gas such as hydrogen and an oxygen-containing gas such as air to react electrochemically with a gas diffusion electrode, and generates electricity and heat simultaneously.

  The side involving a fuel gas such as hydrogen is referred to as the anode and the sign of the relevant means is a, the side involving the oxygen-containing gas such as air is called the cathode and the sign of the related means is c.

  Reference numeral 1 denotes an electrolyte, which is used by a polymer electrolyte membrane or the like that selectively transports hydrogen ions. On both surfaces of the electrolyte 1 (hereinafter also referred to as a membrane), catalytic reaction layers 2a and 2c mainly composed of carbon powder carrying a platinum-based metal catalyst are disposed in close contact with each other. In the catalytic reaction layer, the reactions shown in the above (Chemical Formula 1) and (Chemical Formula 2) occur.

  The fuel gas containing at least hydrogen (hereinafter referred to as anode gas) performs the reaction shown in (Chemical Formula 1) (hereinafter referred to as anode reaction).

  The hydrogen ions that have moved through the electrolyte 1 undergo a reaction shown in (Chemical Formula 2) (hereinafter referred to as a cathode reaction) in an oxygen-containing gas (hereinafter referred to as a cathode gas) and a catalytic reaction layer 2c to generate water. At this time, electricity and heat are generated.

  Further, diffusion layers 3a and 3c having gas permeability and conductivity are disposed in close contact with the outer surfaces of the catalyst reaction layers 2a and 2c. The diffusion layers 3a and 3c and the catalyst reaction layers 2a and 2c constitute electrodes 4a and 4c.

  Reference numeral 5 denotes an electrode electrolyte assembly (hereinafter referred to as MEA), which is formed by the electrodes 4 a and 4 c and the electrolyte 1.

  Gas flow path for mechanically fixing the MEA 5, connecting adjacent MEAs 5 to each other in series, supplying a reaction gas to the electrodes, and carrying away a gas generated by the reaction and surplus gas A pair of conductive separators 7a and 7c formed on the surfaces in contact with the MEA 5 are disposed.

  A basic fuel cell (hereinafter referred to as a cell) includes a membrane 1, a pair of catalytic reaction layers 2a and 2c, a pair of diffusion layers 3a and 3c, a pair of electrodes 4a and 4c, and a pair of separators 7a and 7c. Form.

  The separator 7a or 7c of the adjacent cell is in contact with the separator 7a, 7c on the surface opposite to the MEA 5.

  8a and 8c are cooling water passages provided on the side where the separators 7a and 7c contact each other, and the cooling water flows there. The cooling water moves heat so as to adjust the temperature of the MEA 5 through the separators 7a and 7c.

  Reference numeral 9 denotes an MEA gasket that seals the MEA 5 and the separators 7a and 7c.

  The membrane 1 has a fixed charge, and hydrogen ions exist as a counter ion of the fixed charge. The membrane 1 is required to have a function of selectively allowing hydrogen ions to permeate. For this purpose, the membrane 1 needs to retain moisture. This is because when the film 1 contains moisture, the fixed charge fixed in the film 1 is ionized, and hydrogen, which is a counter ion of the fixed charge, is ionized and can move.

  FIG. 2 is a perspective view of a stack in which cells are stacked.

  Since the voltage of the fuel battery cell is usually as low as about 0.75 V, a plurality of cells are stacked in series so as to obtain a high voltage.

  Reference numeral 21 denotes a current collecting plate for taking out current from the stack, and 22 denotes an insulating plate for electrically insulating the cell from the outside. Reference numeral 23 denotes an end plate that fastens and mechanically holds a stack of stacked cells.

  FIG. 3 is a diagram illustrating the fuel cell power generator according to Embodiment 1 of the present invention.

  Reference numeral 31 denotes an outer casing of the fuel cell system.

  A cleaning unit 32 removes a substance that adversely affects the fuel cell from the fuel gas, and guides the fuel gas from the raw material gas pipe.

  A gate valve 33 controls the flow of the raw material gas.

  A fuel generator 34 generates a fuel gas containing at least hydrogen from the raw material gas.

  During operation of the fuel cell, the raw material gas is guided to the fuel generator 34 through the raw material gas pipe and the gate valve 35.

  Reference numeral 36 denotes a stack, which is shown in detail in FIGS. The fuel gas is led from the fuel generator 34 to the fuel cell stack 36 through the fuel gas pipe.

  A gate valve 37 controls the flow of fuel gas to the fuel cell stack 36. Moreover, the gate valve 37 performs the function of purging and sealing the inert gas in the stack during stop storage. Moreover, the gate valve 37 performs the function of purging and sealing the inert gas in the stack during stop storage.

  The inert gas is not necessarily a so-called noble gas such as helium or neon or nitrogen, but may be a gas inert to the fuel cell such as a raw material gas cleaned in the gas cleaning section. In short, it is a predetermined purge gas (the same applies hereinafter).

  Reference numeral 39 denotes a blower, and the oxygen-containing gas is introduced into the fuel cell stack 36 through the intake pipe.

  A gate valve 41 controls the flow of fuel gas to the fuel cell stack 36.

  The oxygen-containing gas that has not been used in the fuel cell stack 36 is exhausted through the gate valve 42. Further, the gate valve 42 functions to purge and seal the inert gas in the stack during stop storage.

  Reference numeral 40 denotes a humidifier. Since the fuel cell requires moisture, the oxygen-containing gas flowing into the fuel cell stack 36 is humidified here.

  The fuel gas that has not been used in the fuel cell stack 36 flows again into the fuel generator 34 through the off-gas pipe. The gas from the off-gas pipe is used for combustion or the like, and is used for an endothermic reaction or the like for generating fuel gas from the raw material gas.

  During stop storage, the gate valve 42 serves to purge and seal the inert gas in the stack.

  43 is a gate valve that controls off-gas flowing from the fuel cell stack 36 to the fuel generator 34.

  Reference numeral 44 denotes a power circuit unit that extracts power from the fuel cell stack 36. Reference numeral 45 denotes a control unit that controls a gas, a power circuit unit, a gate valve, and the like.

  Reference numeral 46 denotes a pump that causes water to flow from the cooling water inlet pipe to the water path of the fuel cell stack 36. The water that has flowed through the fuel cell stack 36 is carried outside from the cooling water outlet pipe. When water flows through the fuel cell stack 36, the generated heat can be used outside the fuel cell system while maintaining the heated fuel cell stack 36 at a constant temperature.

  The oxygen concentration detectors 50 and 51 detect a change in the oxygen concentration of the inert gas filled in the fuel cell stack 36, and when an oxygen concentration higher than a predetermined concentration is detected, a signal is transmitted to the control unit 45 to operate the gate valve. I do.

  The fuel cell power generator according to Embodiment 1 includes a fuel cell stack 36 composed of fuel cells, a gas cleaning unit 32, a fuel generator 34, a power circuit unit 44, a control unit 45, and an oxygen concentration detector. Has been.

  The means including the oxygen concentration detectors 50 and 51 correspond to the oxygen concentration detection means of the present invention, the control unit 45 corresponds to the purge gas injection means of the present invention, and the fuel cell power generator of the present embodiment is This corresponds to the fuel cell operating device of the present invention.

  The gas cleaning unit 32 corresponds to the fuel gas cleaning means of the present invention.

  The gate valve 41 corresponds to the oxygen-containing gas flow path upstream valve of the present invention, the gate valve 42 corresponds to the oxygen-containing gas flow path downstream valve of the present invention, and the gate valve 37 corresponds to the fuel gas flow path upstream of the present invention. Corresponding to the valve, the gate valve 43 corresponds to the fuel gas flow path downstream valve of the present invention.

  Next, the operation of the fuel cell power generator of this embodiment will be described. While describing the operation of the fuel cell power generator of the present embodiment, an embodiment of the fuel cell operation method of the present invention will also be described (the same applies hereinafter).

  First, a basic operation will be described, and an operation related to storage, which is a point of the fuel cell power generation device of the present embodiment, will be described later.

  In FIG. 3, the valve 33 is opened, and the source gas flows from the source gas pipe into the gas cleaning unit 32.

  As the raw material gas, a hydrocarbon-based gas such as natural gas or propane gas can be used. In this embodiment, 13A, which is a mixed gas of methane, ethane, propane, and butane gas, is used.

  As the gas cleaning part 32, a member for removing gas odorant such as TBM (tertiary butyl mercaptan), DMS (dimethyl sulfide), THT (tetrahydrothiofin) is used. This is because sulfur compounds such as odorants are adsorbed on the catalyst of the fuel cell to become a catalyst poison and inhibit the reaction.

  The fuel generator 34 generates hydrogen by the reaction shown in (Chemical Formula 4).

(Chemical formula 4)
CH ₃ + H ₂ O → 3H ₂ + CO (−203.0 KJ / mol)
Here, a fuel gas containing hydrogen and moisture is created and flows into the fuel cell stack 36 of the fuel cell via the fuel gas pipe.

  The oxygen-containing gas passes through the humidifier 40 by the blower 39 and then flows into the fuel cell stack 36. The exhaust gas of oxygen-containing gas is discharged outside through the exhaust pipe.

  As the humidifier 40, one that flows an oxygen-containing gas into warm water or one that blows water into the oxygen-containing gas can be used. In this embodiment, a total heat exchange type is used. This moves water and heat in the exhaust gas into the oxygen-containing gas that is the raw material carried from the intake pipe when passing through the humidifier 40.

  The cooling water flows from the cooling water inlet pipe to the water path of the fuel cell stack 36 from the pump 46, and then the water is carried to the outside from the cooling water outlet pipe. Although not shown in FIG. 3, a normal water heater or the like is piped in the cooling water inlet pipe or the cooling water outlet pipe. The heat generated in the fuel cell stack 36 of the fuel cell is taken out and can be used for hot water supply or the like.

  The operation of the fuel cell in the fuel cell stack 36 will be described with reference to FIG.

  An oxygen-containing gas such as air is flowed through the gas flow path 6c, and a fuel gas containing hydrogen is flowed through the gas flow path 6a.

  Hydrogen in the fuel gas diffuses through the diffusion layer 3a and reaches the catalytic reaction layer 2a. In the catalytic reaction layer 2a, hydrogen is divided into hydrogen ions and electrons. The electrons are moved to the cathode side through an external circuit. The hydrogen ions permeate the membrane 1 and move to the cathode side and reach the catalytic reaction layer 2c.

  Oxygen in an oxygen-containing gas such as air diffuses through the diffusion layer 3c and reaches the catalytic reaction layer 2c. In the catalyst reaction layer 2c, oxygen reacts with electrons to form oxygen ions, and the oxygen ions react with hydrogen ions to generate water. That is, oxygen-containing gas and fuel gas react around MEA 5 to generate water, and electrons flow.

  Further, heat is generated during the reaction, and the temperature of MEA 5 rises.

  Therefore, the heat generated in the reaction is carried out by water by flowing water or the like through the cooling water paths 8a and 8c. That is, heat and current (electricity) are generated.

At this time, it is important to control the humidity of the introduced gas and the amount of water generated by the reaction. When there is little moisture, the membrane 1 is dried, and the ionization of stationary electrification is reduced, so that the movement of hydrogen is reduced, so the generation of heat and electricity is reduced. On the other hand, if there is too much water, water accumulates around the MEA 5 or around the catalyst reaction layers 2a and 2c, and the gas supply is inhibited and the reaction is suppressed, so that the generation of heat and electricity is reduced. (Hereafter, this state is called flatting.)
The operation after reacting in the fuel cell will be described with reference to FIG.

  The exhaust gas in which the oxygen-containing gas is not used passes through the humidifier 40 and passes heat and moisture to the oxygen-containing gas sent from the blower 39 and is then discharged to the outside.

  The off gas that has not been used for the fuel gas flows again into the fuel generator 34 through the off gas pipe. The gas from the off-gas pipe is used for combustion in the fuel generator 34. Since the reaction for generating the fuel gas from the raw material gas is an endothermic reaction as shown in (Chemical Formula 4), it is used as heat necessary for the reaction.

  The power circuit unit 44 serves to draw DC power from the fuel cell stack 36 after the fuel cell starts generating power.

  The controller 45 controls the other parts of the fuel cell system so as to keep them optimal.

  Next, the operation related to storage, which is a point of the fuel cell power generation device of the present embodiment, will be described more specifically.

  The source gas was city gas 13A, and the oxygen-containing gas was air.

  The temperature of the fuel cell was 70 ° C., the fuel gas utilization rate (Uf) was 70%, and the oxygen utilization rate (Uo) was 40%.

  The fuel gas and air were each humidified to have a dew point of 70 ° C.

A current was taken out from the power circuit unit 44. The current was adjusted to be 0.2 A / cm ² per apparent area of the electrode.

  A hot water storage tank (not shown) is attached to the cooling water inlet pipe and the cooling water outlet pipe.

  The pump 46 was adjusted so that the water temperature in the cooling water inlet pipe was 70 ° C. and the water temperature in the cooling water outlet pipe was 75 ° C.

  The start / stop and storage conditions were as follows.

  FIG. 5 shows changes in stack voltage and oxygen concentration.

  In the operation condition A, after performing a steady operation process, it moved to the stop process 1.

  The current from the stack is taken out by the power circuit unit 44. However, when the voltage of a typical single cell of the fuel cell stack 36 falls below 0.5V, the current take-off is stopped, and when the voltage exceeds 0.7V, the current is again drawn. Was controlled by the control unit 45 so as to be taken out.

  In the stop process 1, the blower 39 is stopped to stop the supply of air to the fuel cell stack 36, the gate valve 48 is opened, and a sulfur compound such as an odorant, a nitrogen compound such as ammonia or an amine substance in the gas cleaning unit 32. The raw material gas from which substances that adversely affect the fuel cell such as carbon monoxide were removed was fed from the pump 49.

  Next, stop process 2 was performed.

  The gate valve 35 is closed, the supply of fuel gas from the fuel generator 34 to the fuel cell stack 36 is stopped, the gate valve 47 is opened, and the gas purifier 32 is used for sulfur compounds such as odorants, ammonia and amine substances. A raw material gas from which substances that adversely affect the fuel cell such as nitrogen compounds and carbon monoxide were removed was flowed into the fuel cell stack 36. The fuel gas extruded from the fuel cell stack 36 by the raw material gas from the fuel cell stack 36 was returned to the fuel generator 34 from the off-gas pipe, and the fuel gas in the fuel cell stack 36 was replaced by the raw material gas.

  Next, stop process 3 was performed.

  In the stop step 3, the gate valve 37 and gate valve 43 on the anode side are closed, the gate valve 41 and gate valve 42 on the cathode side are closed, the fuel cell stack 36 is filled and sealed with the raw material gas, and the pump 49 is stopped. did. In addition, the pump 46 was stopped, and cooling water movement from the outside was eliminated.

  Next, it becomes the storage process 1. In the storage process 1, the temperature of the fuel generator 34 and the fuel cell stack 36, which are at a high temperature, gradually decreases and finally becomes the same as the external temperature.

  In the storage step 2, the oxygen concentration detectors 50 and 51 both detect an oxygen concentration of 10 ppm (approximately equivalent to the lower limit value of the oxygen concentration that can be detected by a normal measurement method). The gate valve 37 and the gate valve 43 on the side are opened, the gate valve 41 and the gate valve 42 on the cathode side are opened, the pump 49 is operated, the raw material gas is reinjected into the fuel cell stack 36 again, and the anode side The gate valve 37 and the gate valve 43 located on the cathode side, and the gate valve 41 and the gate valve 42 on the cathode side were closed and sealed.

  In short, a gate valve is installed upstream and downstream of the oxidant electrode and fuel electrode of the oxygen-containing gas and fuel gas supply passage, an oxygen concentration detector is disposed between the two electrodes and the downstream gate valve, and the oxygen concentration detector is predetermined. By detecting the concentration, the gate valves arranged upstream and downstream of both electrodes are opened and closed, and the inert gas is reinjected again.

  More specifically, by setting the oxygen concentration at which the oxygen concentration detector operates the gate valve to 10 ppm or more, it is possible to realize a fuel cell power generator excellent in durability that does not cause catalyst deterioration due to oxygen.

  Next, it becomes the starting process 1.

  In the start-up process 1, the gate valve 35 is opened, the raw material gas is flowed to the fuel generator 34, the treatment is performed so that the concentration of the substance that contains hydrogen and is not fuel, such as carbon monoxide, becomes below a certain level, and then the gate valve 47 was closed, the pump 49 was stopped, the gate valve 37 and the gate valve 43 on the anode side were opened, and the raw material gas was supplied to the fuel cell stack 36.

  The fuel cell stack 36 may operate the pump 46 to circulate water having a temperature higher than that of the fuel cell stack 36 to increase the temperature.

  Next, the startup process 2 is entered.

  In the starting process 2, the blower 39 was operated, the gate valve 41 and the gate valve 42 on the cathode side were opened, and air was sent into the fuel cell stack 36.

  Next, the fuel and current are controlled, and after the conditions for the steady operation process are reached, the operation is performed as a steady operation process.

  In the present embodiment, an example in which the source gas is reinjected once has been shown. However, the present invention is not limited to this, and the same effect can be obtained even if the same operation is performed several times when the oxygen concentration detector detects a predetermined concentration. Obtained.

  Thus, by stopping the fuel electrode and oxidant electrode of the fuel cell power generation apparatus with an inert gas and sealing, the catalyst is prevented from being deteriorated by oxygen, and the oxygen concentration at both electrodes is measured during storage. Is detected again, the deterioration of the catalyst is suppressed by reinjecting the inert gas again, and a fuel cell power generator excellent in durability that does not cause the catalyst deterioration even during long-term storage can be realized.

  Here, by using the raw material gas cleaned in the gas cleaning section as an inert gas for the fuel cell, deterioration due to start-stop and storage can be reduced easily.

  In the present embodiment described above, detection of the oxygen-containing gas flow path oxygen concentration in the portion between the gate valve 41 and the gate valve 42, and (b) the portion between the gate valve 37 and the gate valve 43. Both the detection of the oxygen concentration in the fuel gas flow path was performed. However, the present invention is not limited to this. Detection of the oxygen-containing gas flow path oxygen concentration in the portion between the gate valve 41 and the gate valve 42, or (b) the fuel gas flow in the portion between the gate valve 37 and the gate valve 43. One of the detection of the road oxygen concentration may be performed.

  Further, in the above-described embodiment, (a) injection of a predetermined purge gas into the portion between the gate valve 41 and the gate valve 42, and (b) between the gate valve 37 and the gate valve 43. Both injections of a predetermined purge gas to the part were performed. However, the present invention is not limited to this, and (a) a predetermined purge gas is injected into the portion between the gate valve 41 and the gate valve 42, or (b) a predetermined portion of the gas is supplied between the gate valve 37 and the gate valve 43. One of the purge gas injections may be performed.

  In addition, in the present embodiment described above, such a predetermined purge gas injection is such that both the detected oxygen-containing gas flow path oxygen concentration and the detected fuel gas flow path oxygen concentration are equal to or greater than a predetermined value. Was done in some cases. However, the present invention is not limited to this, and the injection of the predetermined purge gas is performed when one of the detected oxygen-containing gas flow path oxygen concentration or the detected fuel gas flow path oxygen concentration is equal to or higher than a predetermined value. It may be broken.

(Embodiment 2)
First, the configuration of the fuel cell power generator of the present embodiment will be described with reference mainly to FIG.

  FIG. 4 is a diagram showing a fuel cell power generator according to Embodiment 2 of the present invention.

  The fuel cell power generation device according to the present embodiment is basically the same as the fuel cell power generation device according to the first embodiment shown in FIG. 3, but the anode and cathode of the fuel cell stack 36 are used instead of the oxygen concentration detector. This is a fuel cell power generation device in which a voltage detector 52 for observing the potential change of is arranged. In short, the principle of the present embodiment is that the potential increase caused by the adsorption potential generated by the adsorption of oxygen to the electrode is observed.

  In the present embodiment, the MEA 5 (see FIG. 1) is created as follows.

  Carbon powder acetylene black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd., particle size 35 nm) was mixed with an aqueous dispersion of polytetrafluoroethylene (PTFE) (D1 manufactured by Daikin Industries, Ltd.) and dried. A water repellent ink containing 20% by weight of PTFE was prepared.

  This ink is applied and impregnated on carbon paper (TGPH060H manufactured by Toray Industries, Inc.) serving as a base material for the gas diffusion layer, heat treated at 300 ° C. using a hot air dryer, and the gas diffusion layer (about 200 μm). ) Was formed.

  On the other hand, 66 parts by weight of a catalyst body (50 wt% Pt) obtained by supporting a Pt catalyst on Ketjen Black (Ketjen Black EC, Ketjen Black International Co., Ltd., particle size 30 nm), which is carbon powder. Is mixed with 33 parts by weight (polymer dry weight) of perfluorocarbon sulfonic acid ionomer (5% by weight Nafion dispersion manufactured by Aldrich, USA) which is a hydrogen ion conductive material and a binder, and the resulting mixture is molded. Thus, a catalyst layer (10 to 20 μm) was formed.

  The gas diffusion layer and the catalyst layer obtained as described above were bonded to both surfaces of a polymer electrolyte membrane (Nafion 112 membrane manufactured by DuPont, USA) to produce MEA5.

  Next, a rubber gasket plate was joined to the outer peripheral portion of the membrane 1 of the MEA 5 produced as described above to form manifold holes for circulating cooling water, fuel gas, and oxidant gas.

  On the other hand, conductive separators 7a and 7c made of a graphite plate impregnated with a phenol resin, having an outer dimension of 20 cm × 32 cm × 1.3 mm, and having a gas flow path and a cooling water flow path having a depth of 0.5 mm. Was used.

  The controller 45 corresponds to means including the first purge gas injection means and the second purge gas injection means of the present invention, and the voltage detector 52 corresponds to the potential difference detection means of the present invention. The fuel cell power generator of the form corresponds to the fuel cell operating device of the present invention.

  The gas cleaning unit 32 corresponds to the fuel gas cleaning means of the present invention.

  Next, the operation of the fuel cell power generator of this embodiment will be described.

  Basic operations other than the storage step 2 of the fuel cell stack 36 are the same as those in the first embodiment.

  In the storage step 2 of Embodiment 2, after the storage step 1, the gate valve 41 and the gate valve 42 on the cathode side are temporarily opened, and the source gas is injected only into the cathode.

  At this time, the potential difference between the anode and the cathode of the voltage detector 52 is 10 mV relative to the value before the raw material gas is temporarily injected (corresponding to the aforementioned 10 ppm, which roughly corresponds to the lower limit value of the oxygen concentration detectable by a normal measuring method). When the above change is detected, the gate valve 37 and the gate valve 43 on the anode side are opened by a signal from the control unit 45. Then, the gate valve 41 and the gate valve 42 on the cathode side are opened, the pump 49 is operated, the raw material gas is again injected into the fuel cell stack 36, and the gate valve 37, the gate valve 43 and the cathode side on the anode side are reinjected. Some gate valve 41 and gate valve 42 were closed and sealed.

  FIG. 6 shows the voltage change of the stack and the potential change of the anode different from the cathode into which the source gas was injected.

  In the present embodiment, the temporary raw material gas injection is performed on the cathode side. However, the present invention is not limited to this, and similar results were obtained even when the temporary injection operation was performed on the anode side.

  It should be noted that the source gas is first injected into only one of the cathode and the anode in this manner because oxygen enters from the sealing portion of the fuel cell stack 36 and the like to the entire fuel cell stack 36, so that the potentials at both electrodes are almost equal. This is because it often changes.

  In this way, during inactive storage, inert gas is temporarily purged to one of the fuel electrode or oxidant electrode, changes in the potential difference between both electrodes are detected, and inert gas is reinjected again to suppress catalyst deterioration. In addition, it is possible to realize a fuel cell power generator excellent in durability that does not cause catalyst deterioration even during long-term storage.

  In short, a gate valve is installed upstream and downstream of the oxidant electrode and the fuel electrode in the oxygen-containing gas and fuel gas supply passages, a voltage detection device for detecting the potential difference between the oxidant electrode and the fuel electrode is arranged, and inert gas is collected. When the potential difference between the two electrodes at the time of additional purge shows a predetermined value or more, the gate valve disposed upstream and downstream of both electrodes is opened and closed, and the inert gas is reinjected again.

  More specifically, the voltage detector activates the gate valve and reinjects the inert gas, and the change in potential difference between the two electrodes is set to 10 mV or more so that the catalyst does not deteriorate due to intrusion gas from the outside or trace gas leak. An excellent fuel cell power generator can be realized.

(Comparative example)
The comparative example is similar to the first embodiment and the second embodiment, but does not include an oxygen concentration detector and a voltage detector, and detects a predetermined potential difference by reinjecting the raw material gas in the storage process 2. This is a start / stop and storage method that is performed only when

  FIG. 7 shows changes in the stack voltage and anode potential in the comparative example.

  From the change in the stack voltage shown in FIG. 5, even if oxygen has entered the fuel cell stack 36 during the storage process, no change is seen in the voltage of the fuel cell stack 36 (as described above, oxygen is the fuel In order to penetrate the entire battery stack 36, the potentials of both electrodes change substantially equally, and the voltage of the fuel cell stack 36, which is the difference between these potentials, does not change). Therefore, by providing the outer casing 31 with the oxygen concentration detectors 50 and 51, the influence of oxygen in the fuel cell stack 36 can be observed.

  That is, by performing the operation of the first embodiment, it is possible to prevent catalyst deterioration, and it is possible to provide a fuel cell power generator that is excellent in durability even when the start / stop operation is performed.

  From the change in the stack voltage shown in FIG. 6, a change is observed in the potential difference between the two electrodes by temporarily injecting the source gas into the cathode or anode. This is considered to be a potential change caused by oxygen entering from the outside.

  In many cases, even if the potential difference between the two electrodes is zero, the potential itself increases (for the above-described reason, zero potential difference between the two electrodes is observed even when oxygen enters the fuel cell stack 36). When the anode is affected by the potential increase, Ru elution occurs. In the second embodiment, this change in potential can be observed with a voltage detector using the change in potential of each cell when the source gas is allowed to flow temporarily to one electrode side.

  That is, by performing the operation of the second embodiment, it is possible to prevent not only catalyst deterioration due to oxygen but also catalyst deterioration due to potential rise, and provide a fuel cell power generator that is excellent in durability even when start / stop operation is performed. be able to.

  FIG. 8 shows the durability results of the stacks subjected to the start / stop methods of the first embodiment, the second embodiment, and the comparative example.

  As shown in FIG. 8, the first and second embodiments in which the raw material gas is reinjected in the storage process have an extremely low value of the durability deterioration rate at the number of start / stop times of 10,000 as compared with the comparative example. Can be maintained.

  As described above, this indicates that catalyst deterioration due to oxygen and catalyst deterioration due to potential increase could be prevented by reinjecting the raw material gas when storage was stopped.

  According to the present invention, it is possible to provide a fuel cell power generator that can exhibit high durability without causing catalyst deterioration even when the fuel cell power generator is stopped and stored for a long period of time.

  The program of the present invention is a program for causing a computer to execute the operations of all or part of the above-described fuel cell operation method of the present invention (or process, operation, action, etc.). It is a program that works in cooperation.

  The recording medium of the present invention is a program for causing a computer to execute all or a part of all or some of the steps (or processes, operations, actions, etc.) of the above-described fuel cell operating method of the present invention. Is a recording medium that can be read by a computer, and that the read program executes the operation in cooperation with the computer.

  The “part of steps (or process, operation, action, etc.)” of the present invention means one or several of the plurality of steps.

  In addition, the “step (or process, operation, action, etc.) operation” of the present invention means all or a part of the operation of the step.

  Further, one usage form of the program of the present invention may be an aspect in which the program is recorded on a computer-readable recording medium and operates in cooperation with the computer.

  Further, one usage form of the program of the present invention may be an aspect in which the program is transmitted through a transmission medium, read by a computer, and operated in cooperation with the computer.

  The recording medium includes a ROM and the like, and the transmission medium includes a transmission medium such as the Internet, light, radio waves, sound waves, and the like.

  The computer of the present invention described above is not limited to pure hardware such as a CPU, and may include firmware, an OS, and peripheral devices.

  As described above, the configuration of the present invention may be realized by software or hardware.

  The fuel cell power generator according to the present invention is a fuel cell power generator excellent in durability that can be started and stopped, and is useful as a home cogeneration system, a distributed power source, and the like. It can also be applied to applications such as automobile and portable equipment power supplies.

Schematic cross-sectional view for explaining a partial structure of a unit cell of a polymer electrolyte fuel cell according to Embodiment 1 of the present invention BRIEF DESCRIPTION OF THE DRAWINGS Schematic for demonstrating the structure of the stack which laminated | stacked the polymer electrolyte fuel cell in Embodiment 1 of this invention Schematic of the fuel cell power generator in Embodiment 1 of the present invention Schematic of the fuel cell power generator in Embodiment 2 of the present invention Explanatory drawing which showed the relationship between the voltage change and oxygen concentration in the start-stop operation of the fuel cell power generator in Embodiment 1 of this invention Explanatory drawing which showed the relationship between the voltage change in the start-stop operation of the fuel cell power generator in Embodiment 2 of this invention, and the electric potential change between the both poles of an anode and a cathode Explanatory drawing which showed the voltage change in the start-stop operation of the fuel cell power generator in the comparative example of this invention Explanatory drawing which showed the relationship between the frequency | count of start / stop of fuel cell power generator and durability in Embodiment 1, Embodiment 2 of this invention, and a comparative example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolyte membrane 2a, 2c Catalytic reaction layer 3a, 3c Diffusion layer 7a, 7c Separator 21 Current collecting plate 22 Insulating plate 31 Outer housing 32 Clean part 34 Fuel generator 36 Fuel cell stack 40 Humidifier 44 Electric power circuit part 45 Control part
50, 51 Oxygen concentration detector 52 Voltage detector

Claims (11)

During the storage period of the fuel cell, (1) oxygen provided upstream from the oxidant electrode in the oxygen-containing gas flow path for supplying and discharging a predetermined oxygen-containing gas to and from the oxidant electrode of the fuel cell Detection of the oxygen-containing gas flow path oxygen concentration in a portion between the containing gas flow path upstream valve and the oxygen-containing gas flow path downstream valve provided downstream of the oxidant electrode in the oxygen-containing gas flow path; and (2) A fuel gas flow path upstream valve provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to and from the fuel electrode of the fuel cell, and the fuel gas Oxygen concentration detection means for detecting the fuel gas flow path oxygen concentration in the portion between the supply flow path and the fuel gas flow path downstream valve provided downstream of the fuel electrode;
When the detected oxygen-containing gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration is a predetermined value or more, (a) the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow Injection of a predetermined purge gas into a portion between the downstream valve and / or (b) a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve A fuel cell operating device comprising purge gas injection means for performing injection. A fuel gas cleaning means for cleaning the predetermined fuel gas;
The fuel cell operating device according to claim 1, wherein the predetermined purge gas is the purified fuel gas.   The fuel cell operating device according to claim 1, wherein the predetermined value is 10 ppm. During the storage period of the fuel cell, (1) oxygen provided upstream from the oxidant electrode in the oxygen-containing gas flow path for supplying and discharging a predetermined oxygen-containing gas to and from the oxidant electrode of the fuel cell Detection of the oxygen-containing gas flow path oxygen concentration in a portion between the containing gas flow path upstream valve and the oxygen-containing gas flow path downstream valve provided downstream of the oxidant electrode in the oxygen-containing gas flow path; and (2) A fuel gas flow path upstream valve provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to and from the fuel electrode of the fuel cell, and the fuel gas An oxygen concentration detection step for detecting a fuel gas flow path oxygen concentration in a portion between the supply flow path and a fuel gas flow path downstream valve provided downstream of the fuel electrode;
When the detected oxygen-containing gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration is a predetermined value or more, (a) the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow Injection of a predetermined purge gas into a portion between the downstream valve and / or (b) a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve A fuel cell operating method comprising a purge gas injection step for performing injection.   5. The fuel cell operation method according to claim 4, wherein the detected oxygen-containing gas flow path oxygen concentration and / or the detected fuel gas flow path oxygen concentration is equal to or greater than a predetermined value, Injection of a predetermined purge gas into a portion between the gas flow path upstream valve and the oxygen-containing gas flow path downstream valve, and / or (b) the fuel gas flow path upstream valve and the fuel gas flow path downstream valve; A program for causing a computer to execute a purge gas injection step for injecting a predetermined purge gas into a portion between the two. During the storage period of the fuel cell, (1) oxygen provided upstream from the oxidant electrode in the oxygen-containing gas flow path for supplying and discharging a predetermined oxygen-containing gas to and from the oxidant electrode of the fuel cell Injecting a predetermined purge gas into the portion between the containing gas flow path upstream valve and the oxygen containing gas flow path downstream valve provided downstream of the oxidant electrode in the oxygen containing gas flow path, or (2 ) A fuel gas flow path upstream valve provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to and from the fuel electrode of the fuel cell; and in the fuel gas supply flow path A first purge gas injecting means for injecting a predetermined purge gas into a portion between the fuel gas flow path downstream valve provided downstream of the fuel electrode;
A potential difference detecting means for detecting a potential difference between the potential of the oxidant electrode and the potential of the fuel electrode;
Injection of a predetermined purge gas into a portion between the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow path downstream valve, or between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve When the change in the detected potential difference before and after the injection of the predetermined purge gas to the portion is greater than or equal to a predetermined value, (a) the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow Injection of a predetermined purge gas into the portion between the downstream valve and (b) injection of a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve. A fuel cell operating device comprising a second purging gas injection means for performing again. A fuel gas cleaning means for cleaning the predetermined fuel gas;
The fuel cell operating device according to claim 6, wherein the predetermined purge gas is the purified fuel gas.   The fuel cell operating device according to claim 6, wherein the predetermined value is 10 mV. During the storage period of the fuel cell, (1) oxygen provided upstream from the oxidant electrode in the oxygen-containing gas flow path for supplying and discharging a predetermined oxygen-containing gas to and from the oxidant electrode of the fuel cell Injecting a predetermined purge gas into the portion between the containing gas flow path upstream valve and the oxygen containing gas flow path downstream valve provided downstream of the oxidant electrode in the oxygen containing gas flow path, or (2 ) A fuel gas flow path upstream valve provided upstream of the fuel electrode in the fuel gas flow path for supplying and discharging a predetermined fuel gas to and from the fuel electrode of the fuel cell; and in the fuel gas supply flow path A first purge gas injection step for injecting a predetermined purge gas into a portion between the fuel gas flow path downstream valve provided downstream of the fuel electrode, the potential of the oxidant electrode and the fuel Pole potential and A potential difference detection step for detecting the potential difference of
Injection of a predetermined purge gas into a portion between the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow path downstream valve, or between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve When the change in the detected potential difference before and after the injection of the predetermined purge gas to the portion is greater than or equal to a predetermined value, (a) the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow Injection of a predetermined purge gas into the portion between the downstream valve and (b) injection of a predetermined purge gas into the portion between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve. And a second purge gas injection step which is performed again.   The fuel cell operating method according to claim 9, wherein in the storage period of the fuel cell, (1) in the oxygen-containing gas flow path for supplying and discharging a predetermined oxygen-containing gas to and from the oxidant electrode of the fuel cell. With respect to a portion between an oxygen-containing gas flow path upstream valve provided upstream from the oxidant electrode and an oxygen-containing gas flow path downstream valve provided downstream from the oxidant electrode in the oxygen-containing gas flow path Injection of a predetermined purge gas, or (2) on a fuel gas channel provided upstream of the fuel electrode in the fuel gas channel for supplying and discharging a predetermined fuel gas to and from the fuel electrode of the fuel cell A first purge gas injection step for injecting a predetermined purge gas into a portion between the flow valve and the fuel gas flow path downstream valve provided downstream of the fuel electrode in the fuel gas supply flow path And said Injection of a predetermined purge gas into a portion between the element-containing gas flow path upstream valve and the oxygen-containing gas flow path downstream valve, or between the fuel gas flow path upstream valve and the fuel gas flow path downstream valve And (a) the oxygen-containing gas flow path upstream valve and the oxygen-containing gas flow path when the change in the detected potential difference before and after the injection of the predetermined purge gas to the portion is greater than or equal to a predetermined value. Injection of a predetermined purge gas into the portion between the downstream valve and (b) injection of a predetermined purge gas into the portion between the fuel gas passage upstream valve and the fuel gas passage downstream valve again. A program for causing a computer to execute a second purge gas injection step to be performed.   A recording medium carrying the program according to claim 5 or 10, which can be processed by a computer.

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