JP5052776B2 - Stop storage start method and stop storage start program of fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system that introduces an oxidant gas and a fuel gas to generate power by a chemical reaction and a technique for stopping, storing, and starting the fuel cell system.

  A fuel cell supplies a fuel such as hydrogen and an oxidant such as air to the fuel cell body and causes it to react electrochemically, thereby converting the chemical energy of the fuel directly into electrical energy and taking it out. It is. This fuel cell is highly efficient and environmentally friendly despite its relatively small size, so it is expected to be used in a wide range of applications such as industrial use in factories and hospitals, general households, and automobiles. Has been.

  In such a fuel cell, the fuel gas used for the electrochemical reaction can be supplied by supplying hydrogen gas from a hydrogen cylinder or a hydrogen storage alloy, or by reforming a hydrocarbon-based raw fuel by catalytic reaction. Gas may be supplied. As a method for supplying the oxidant gas, there are a case where oxygen gas is supplied from an oxygen cylinder and a case where air is supplied using means such as a blower or a compressor.

  On the other hand, when the operation of the fuel cell is stopped, an inert gas such as nitrogen is enclosed and stored. However, even when the inert gas is sealed in this way, the air as the outside air enters the gas flow path of the fuel cell, and a certain amount of oxygen is contained in both the fuel electrode and the oxidant electrode. . For example, in Patent Document 1, when a fuel gas containing hydrogen is introduced into the fuel electrode in a state where oxygen is contained in both the fuel electrode and the oxidant electrode in this way, a corrosion reaction due to the partial cell occurs, and the cell voltage Has been pointed out.

  Here, the corrosion reaction by the partial battery will be described with reference to FIG. FIG. 11 is a diagram showing the flow of current in the cell surface at the time of startup, in which 21 is a fuel electrode, 22 is an oxidant electrode, 23 is an electrolyte existing between the fuel electrode 21 and the oxidant electrode 22, and 24. Is a fuel gas flow path, and 25 is an oxidant gas flow path.

  In a state where both the fuel electrode 21 and the oxidant electrode 22 are in an atmosphere containing oxygen, when a fuel gas containing hydrogen is introduced into the fuel gas passage 24, hydrogen exists in the vicinity of the fuel inlet, so that the hydrogen potential ( 0V), and the hydrogen potential does not reach the vicinity of the fuel outlet, so the air potential remains unchanged. In the surface of the fuel electrode 21, a potential gradient is generated from the fuel outlet toward the fuel inlet.

When current flows in the surface of the fuel electrode 21 according to this potential gradient, a current in the reverse direction flows in the surface of the oxidant electrode 22 so as to cancel it. In this case, at the fuel inlet, hydrogen is decomposed into protons as in the following formula (1), and carries a current from the fuel electrode 21 to the oxidant electrode 22.
H ₂ → 2H ⁺ + 2e ⁻ (1)

At the fuel outlet, protons, which are current carriers, are generated from carbon according to the reaction of the following equation (2). By this reaction, the carbon supported on the catalyst disappears, and the battery performance is lowered.
C + 2H ₂ O → CO ₂ + 4H ⁺ + 4e ⁻ (2)

  For this reason, generally, at the time of start-up, first, an inert gas such as nitrogen is introduced to remove oxygen from both electrodes, so-called inert gas purge is performed, and then start-up is performed.

  In the above-described fuel cell starting method, nitrogen gas is generally supplied from the cylinder as an inert gas for purge, and thus there is a problem that it takes labor and cost for replacing the cylinder. In particular, when used in a general household, there is a demand to avoid replacing the nitrogen cylinder. Moreover, in the case of automobiles, there is a problem that the startup time becomes long because of purging at startup.

  Further, as a means for suppressing such partial cell reaction, there is a method of removing oxygen in the fuel electrode by purging the fuel electrode with nitrogen gas or the like as described above, but even if purged with nitrogen gas, Since oxygen adsorbed on the catalyst layer of the fuel electrode cannot be completely removed, there is a problem that the partial cell reaction occurs and the performance of the fuel cell is lowered.

  Conventionally, methods as shown in Patent Documents 2 to 4 have been proposed as methods for preventing deterioration of a battery due to start and stop.

  In Patent Document 2, the operation is stopped and stored in a state where water is sealed in a fuel gas channel or an oxidant gas channel of a battery body or a humidified inert gas is sealed. A method for stopping and storing a polymer electrolyte fuel cell is described.

  In Patent Document 3, after the fuel is supplied to the fuel electrode and the supply of air to the oxidant electrode is stopped, the oxygen of the oxidant electrode is consumed by the resistance load, and then the oxidant electrode is sealed and the potential of the oxidant electrode is set. A method for preventing carbon corrosion and catalyst aggregation in the catalyst layer by keeping it low is described.

Patent Document 4 describes a method for preventing gas from being mixed into the battery at the time of stoppage by providing opening / closing means upstream and downstream of the fuel electrode and the oxidant electrode.
US Pat. No. 6,514,635 Patent No. 3297125 JP-A-6-333586 JP 2002-93448 A

  However, the conventional method for stopping and storing the fuel cell system as described above has the following problems.

  The stopped storage method of Patent Document 2 is intended for prevention of drying of the solid polymer membrane, and it is impossible to remove oxygen adsorbed on the catalyst layer. As a result, the partial cell reaction can be prevented. Since this is not possible, there is a problem that the battery performance deteriorates.

Since the stopping method of Patent Document 3 purges only the fuel electrode with an inert gas, the consumption of the inert gas can be reduced. However, the inert gas is still necessary and the inert gas cylinder itself can be omitted. Can not.

  Since the method of Patent Document 4 requires purging of the oxidant electrode, an external power source and a purge gas pipe are required, which causes an increase in cost and makes it difficult to reduce the size of the plant.

  The present invention has been made to solve the above-described problems of the prior art, and its purpose is to stop, store, and start a fuel cell system without the need for inert gas purging or addition of a special device. It is to provide a fuel cell system capable of suppressing the accompanying degradation of fuel cell performance, its stop storage start method, and stop storage start program.

  In order to achieve the above object, the present invention provides a fuel gas and oxidant gas stopping / supplying operation in the stopping process and starting process of the fuel cell system, and fuel gas sealing provided upstream and downstream of the fuel cell main body. By limiting the operation procedure of the opening and closing operation of the means and the oxidant gas sealing means, it is possible to avoid a state where hydrogen is locally depleted in the fuel electrode and oxygen is present in the oxidant electrode. .

  A stop storage activation method of the present invention includes a fuel cell main body having a fuel electrode, an oxidant electrode, a fuel gas flow channel, and an oxidant gas flow channel, and a fuel gas supply means for supplying fuel gas to the fuel cell main body, An oxidant gas supply means for supplying an oxidant gas to the fuel cell main body; a fuel gas sealing means for opening and closing the upstream and downstream sides of the fuel gas system of the fuel cell main body to enclose the fuel gas in the fuel cell main body; and the fuel A method for stopping, storing, and starting a fuel cell system including an oxidant gas sealing means for sealing an oxidant gas in a fuel cell body by opening and closing upstream and downstream of the oxidant gas system of the battery body. It has the following characteristics.

  That is, in the stopping process, the fuel gas sealing means and the oxidant gas sealing means are closed in a state where supply of the fuel gas and the oxidant gas by the fuel gas supply means and the oxidant gas supply means is stopped. Further, during storage, the fuel gas sealing means and the oxidant gas sealing means are kept closed. In the starting process, the fuel gas sealing means is opened, and after the fuel gas supply means starts supplying fuel gas to the fuel cell main body, the oxidant gas sealing means is opened and the oxidant gas supply means Supply of oxidant gas to the fuel cell body is started.

  According to such an operation procedure, when the fuel gas and the oxidant gas are stopped, the fuel gas sealing means and the oxidant gas sealing means are closed while the supply of the fuel gas and the oxidant gas is stopped. After moving through the polymer membrane and reacting, hydrogen can remain in the fuel electrode. Further, at the time of storage, the state in which hydrogen remains in the fuel electrode can be maintained by keeping the fuel gas sealing means and the oxidant gas sealing means closed. At the time of start-up, after the fuel gas sealing means is opened and the supply of fuel gas is started, the oxidant gas sealing means is opened and the supply of the oxidant gas is started, so that hydrogen is surely present in the fuel electrode. In this state, the supply of the oxidant gas can be started.

  Therefore, it is possible to reliably avoid an inconvenient state in which hydrogen is locally depleted in the fuel electrode and oxygen is present in the oxidant electrode in any of the operations of stopping, storing, and starting.

  As described above, according to the present invention, the stop and supply operation of the fuel gas and the oxidant gas in the stop process and the start process of the fuel cell system, the fuel gas sealing means provided on the upstream and downstream of the fuel cell body, and the oxidant By limiting the operation procedure for opening and closing the gas sealing means, it is possible to suppress the deterioration of the fuel cell performance due to the stop, storage and start-up of the fuel cell system without the need for inert gas purging or the addition of special equipment. A fuel cell system, its stop storage start method, and stop storage start program can be provided.

  Embodiments to which the present invention is applied will be specifically described below with reference to the drawings.

[First Embodiment]
[Constitution]
FIG. 1 is a block diagram showing a configuration of a fuel cell system according to a first embodiment to which the present invention is applied.

  As shown in FIG. 1, the fuel cell system of the first embodiment includes a fuel cell main body 1, and the fuel cell main body 1 includes a fuel electrode 2, an oxidant electrode 3, and a battery cooling unit 4. Yes. The fuel gas is supplied from the fuel gas supply means 5 to the fuel electrode 2 of the fuel cell main body 1, the oxidant gas is supplied from the oxidant gas supply means 6 to the oxidant electrode 3 of the fuel cell main body 1, and the cooling water is supplied. The cooling water pump 7 supplies the battery cooling unit.

  According to the present invention, the fuel gas upstream sealing means 8 is installed between the fuel gas supply means 5 and the fuel electrode 2, and the fuel gas downstream sealing means 9 is installed downstream of the fuel electrode 2. These fuel gas upstream sealing means 8 and fuel gas downstream sealing means 9 open and close the upstream and downstream sides of the fuel gas system of the fuel cell body 1 to seal the fuel gas in the fuel cell body 1.

  Similarly, an oxidizing gas upstream sealing means 10 is installed between the oxidizing gas supply means 6 and the oxidizing agent electrode 3, and an oxidizing gas downstream sealing means 11 is installed downstream of the oxidizing agent electrode 3. These oxidant gas upstream sealing means 10 and oxidant gas downstream sealing means 11 open and close the upstream and downstream of the oxidant gas system of the fuel cell body 1 to seal the oxidant gas in the fuel cell body 1.

  In addition, the fuel gas upstream sealing means 8, the fuel gas downstream sealing means 9, the oxidant gas upstream sealing means 10, and the oxidant gas downstream sealing means 11 are controlled by the plant control unit 12.

[Action]
FIG. 2 is a flowchart showing a stop storage start procedure by the fuel cell system of the present embodiment.

  As shown in FIG. 2, when a power generation stop command is issued from the power generation state (YES in S110), the plant control unit 12 uses the fuel gas supplied by the fuel gas supply means 5 and the oxidant gas supply means 6 as the stop procedure. The supply of the oxidant gas is stopped (S111), and the fuel gas upstream sealing means 8, the fuel gas downstream sealing means 9, the oxidant gas upstream sealing means 10, and the oxidant gas downstream sealing means 11 are closed (S112). As a result, the fuel gas and the oxidant gas are sealed in the fuel cell main body 1. During the storage from the stop to the start, the four enclosing means 8 to 11 remain closed.

  In such an encapsulated state of the fuel gas and the oxidant gas from the stop time to the storage time, a part of hydrogen in the fuel electrode 2 permeates to the oxidant electrode 3 through the electrolyte, and conversely, the oxidant electrode 3 Part of the oxygen passes through the electrolyte to the fuel electrode 2 and a reaction occurs in which hydrogen and oxygen generate water on the catalyst. In a plant equipped with a reformer that extracts hydrogen from raw fuel, the hydrogen concentration in the fuel gas is about 80% in the case of the steam reforming method. On the other hand, since air is generally used as the oxidant gas, the oxygen concentration in the oxidant gas is about 21%.

Void volume between the fuel gas upstream sealed unit 8 and the fuel gas downstream enclosing means 9, the fuel electrode gas channel, the fuel electrode manifold, is represented by the sum of the volume of the fuel electrode pipe, where a V _-Fuel Define. Similarly, the gap volume between the oxidant gas upstream sealing means 8 and the oxidant gas downstream sealing means 9 is represented by the sum of the volumes of the oxidant electrode gas flow path, the oxidant electrode manifold, and the oxidant electrode pipe. Then, it defines as V- _air .

In this case, the amount of hydrogen in the fuel electrode gap volume immediately after the stop of power generation is V _−fuel × 0.8 (= hydrogen concentration), and the amount of oxygen in the oxidizer electrode gap volume is V _−air × 0.21 (= oxygen). Density). Since 1 mol of oxygen reacts with 2 mol of hydrogen, theoretically, after the hydrogen of the fuel electrode and oxygen of the oxidant electrode move and react through the polymer film under the condition of the following formula (3), the fuel Hydrogen will remain at the pole.
V- _fuel × 0.8> 2 × V- _air × 0.21 (3)
(→ V- _fuel > 2 × V- _air × 0.21 / 0.8)

In practice, because of the leak from the very small leak and the cell stack seals the valve and piping from the atmosphere, from the standpoint of sufficient and long-term residual hydrogen to the fuel electrode, the fuel electrode void volume V _-Fuel is It is desirable to make it as large as possible with respect to the oxidant electrode void volume. Further, in this case, not only the oxygen leak-in to the fuel electrode but also the oxygen leak-in to the oxidant electrode can be suppressed at the same time, so that the hydrogen remaining effect at the fuel electrode can be maintained.

  Next, the startup procedure will be described. When a startup command is issued from the storage state (YES in S120), the plant control unit 12 first opens the fuel gas upstream sealing means 8 and the fuel gas downstream sealing means 9 as a startup procedure, and the fuel gas supplied by the fuel gas supply means 5 Is started (S121). Thereafter, the oxidant gas upstream sealing means 10 and the oxidant gas downstream sealing means 11 are opened, and supply of the oxidant gas by the oxidant gas supply means 6 is started (S122), whereby the fuel cell main body 1 is in a power generation start state. (S123). In addition, about battery cooling water, what is necessary is just to start supply in the arbitrary times of an electric power generation start from a starting instruction | command.

  By carrying out such a series of stop storage start procedures, in any operation of stop, storage and start, there is a problem that “hydrogen is locally depleted in the fuel electrode and oxygen is present in the oxidizer electrode”. It is possible to avoid such a state reliably.

[effect]
As described above, according to the present embodiment, the stop and supply operation of the fuel gas and the oxidant gas in the stop process and start-up process of the fuel cell system, the fuel gas sealing means provided in the upstream and downstream of the fuel cell body, and the oxidation By limiting the operation procedure of the opening and closing operation of the agent gas sealing means, it is possible to suppress the deterioration of the fuel cell performance due to the stop, storage and start-up of the fuel cell system without the need for inert gas purge or the addition of special equipment be able to.

FIG. 3 is a graph showing the relationship between the number of start / stop operations and the voltage in the stop storage start procedure according to the method of the present invention and the stop storage start procedure according to the method of the comparative example. As shown in FIG. 3, in the case of the stop storage start procedure without a normal N ₂ purge, the voltage is lower than the minimum voltage required for operation after about 20 start / stop operations. Further, even if there is N ₂ purge, the voltage is lower than the minimum voltage required for operation by starting and stopping about 500 times. Therefore, when starting and stopping at intervals of about once a week or more, if the N ₂ purge is performed, the minimum voltage required for operation can be maintained for about 10 years. The amount of voltage drop is not a problem level.

However, as a usage that is normally assumed in a household fuel cell plant, it is usual to stop power generation at night or when going out, so that it is necessary to start or stop once or twice a day. In this case, even if a suspended storage activation procedure using N ₂ purge is adopted, the battery voltage drops in one or two years, and operation becomes impossible. On the other hand, when the suspended storage activation procedure method according to the present invention is implemented, there is almost no voltage decrease even when the number of activation / deactivation is 500 times, and the effect of suppressing the battery voltage decrease due to activation / deactivation is great.

[Effect of using porous material separator]
FIG. 12 shows a configuration example of the fuel cell when a porous material is used for the fuel cell separator. In FIG. 12, as separators constituting the fuel gas flow path and the oxidant flow path on both sides of the electrode 31 and the separator constituting the coolant flow path, both are porous material separators made of a porous material, that is, A fuel gas channel porous material separator 32, an oxidant gas channel porous material separator 33, and a coolant channel porous material separator 34 are used. The electrode 31 is an electrode complex in which a fuel electrode and an oxidant electrode are incorporated.

  In the case of a polymer electrolyte fuel cell, the porous material separator has two functions: a function of humidifying a gas introduced during normal power generation and a function of removing excess water generated by the cell reaction from the electrode. With these functions, in the fuel cell using the porous material separators 32 to 34, it is not necessary to humidify the polymer membrane, and flooding due to reaction product water can be prevented. Moreover, in the direct methanol fuel cell to which the porous material separator is applied, methanol can be supplied to the electrode through the porous material separator.

  In the fuel cell in which such porous material separators 32 to 34 are incorporated, an effect in the case where the stop storage start procedure of the first embodiment is applied will be described. First, when the porous material separators 32 to 34 are not used, the gas of the fuel electrode and the oxidant electrode is consumed at the time of stop storage, and the temperature also decreases. Thus, since a very small amount of air leaks in from the outside, hydrogen in the fuel cell is consumed, and the effect of remaining hydrogen on the fuel electrode, which is the object of the present invention, is slightly reduced.

  On the other hand, when the porous material separators 32 to 34 as shown in FIG. 12 are used, even if the pressure of the fuel electrode and the oxidant electrode is reduced during the stop storage, the coolant, the fuel electrode, and the coolant. Since the coolant moves to the fuel gas channel and the oxidant gas channel due to the pressure difference between the oxidant electrode and the oxidant electrode, the pressure drop between the fuel electrode and the oxidant electrode is alleviated. For this reason, the leak-in of air from the outside can be suppressed, and the hydrogen remaining effect of the fuel electrode can be maintained. Moreover, since the fall of a pressure can be suppressed, it also has the effect of relieving the mechanical damage of battery material.

[Modification of First Embodiment]
4 to 6 show a plurality of modified examples including an operation (S113) of connecting a resistance load and consuming oxygen of the oxidant electrode in the stop procedure in the stop storage start procedure in the first embodiment. It is a flowchart. Below, each procedure is demonstrated one by one.

  In the stop storage start procedure shown in FIG. 4, in the stop procedure, the supply of the fuel gas and the oxidant gas by the fuel gas supply means 5 and the oxidant gas supply means 6 is stopped (S111), the fuel gas upstream sealing means 8, the fuel After the gas downstream sealing means 9, the oxidant gas upstream sealing means 10, and the oxidant gas downstream sealing means 11 are closed (S112), a resistance load is connected and oxygen in the oxidant electrode is consumed (S113). The storage state and the startup procedure are the same as the stopped storage startup procedure of FIG.

  This stop storage start procedure shown in FIG. 4 is a procedure useful mainly when the external power supply is lost due to an abnormality in the system power supply, etc., and air is mixed into the battery from the outside by connecting a resistive load during storage. Even in this case, it is possible to suppress an increase in the potential of the oxidizer electrode and to avoid a state in which corrosion due to the partial cell reaction occurs.

  In addition, when the storage period is long or when the sealing performance of the battery is poor, air may be mixed in the oxidizer electrode. In this case, the voltage of the cell rises when fuel is introduced into the fuel electrode even before air is supplied to the oxidant electrode, and a partial cell reaction as shown in FIG. 11 occurs. Therefore, in the case of a single cell, by connecting a resistor at the time of fuel introduction, an increase in voltage can be suppressed and deterioration of the battery can be suppressed.

  However, when multiple cells are stacked, if a resistor is connected at the time of fuel introduction with a large amount of air in the gas groove of the oxidizer electrode, the fuel will flow between the multiple cells. There is a time difference in introduction. As a result, for cells that have been introduced with fuel, the increase in voltage can be suppressed and deterioration of the battery due to partial cells can be suppressed. However, for cells that are delayed in introduction of fuel, current is forced to the electrode without fuel. Therefore, the fuel is deficient and the fuel electrode is corroded.

  However, when the fuel electrode 2 and the oxidant electrode 3 are blocked from the external space by the gas sealing means 8 to 11 as in the present invention, the amount of air mixed into the oxidant electrode is limited, and Even if there is a difference in fuel introduction time between cells, the voltage rise between cells is suppressed, and the voltage distribution between cells becomes very small. It becomes possible to suppress. Furthermore, when a resistor is not connected at the time of fuel introduction in a state where a small amount of air is mixed in the oxidizer electrode, there is a concern that the battery deteriorates due to a voltage increase at the time of fuel introduction.

  Further, in the stop storage start procedure shown in FIG. 5, in the stop procedure, the supply of the fuel gas and the oxidant gas by the fuel gas supply means 5 and the oxidant gas supply means 6 is stopped (S111), and the oxidant gas upstream sealing means. 10 and the oxidant gas downstream sealing means 11 are closed (S1121), then a resistance load is connected to consume oxygen in the oxidant electrode (S113), and then the fuel gas upstream sealing means 8 and the fuel gas downstream sealing means 9 is closed (S1122). The storage state and the startup procedure are the same as the stopped storage startup procedure of FIG.

  In order to prevent the deterioration of the battery, it is important to maintain the fuel electrode at the hydrogen potential. However, in the stopped storage start procedure shown in FIG. 5, when the oxygen in the oxidizer electrode is consumed by the resistance load, Since the oxidant gas sealing means 10 and 11 are already closed, it is possible to prevent the inflow of air from the outside to the oxidant electrode, and the hydrogen consumption of the fuel electrode during the stop operation can be reduced. It is possible to extend the remaining time of hydrogen.

  Further, in the stop storage start procedure shown in FIG. 6, in the stop procedure, the supply of the fuel gas and the oxidant gas by the fuel gas supply means 5 and the oxidant gas supply means 6 is stopped (S111), and the resistance load is connected. After the oxygen in the oxidant electrode is consumed (S113), the fuel gas upstream sealing means 8, the fuel gas downstream sealing means 9, the oxidant gas upstream sealing means 10, and the oxidant gas downstream sealing means 11 are closed (S112). The storage state and the startup procedure are the same as the stopped storage startup procedure of FIG.

  Unlike the stop storage start procedure shown in FIG. 6, when the gas filling means is closed, the negative pressure is consumed when the fuel electrode hydrogen and the oxidant electrode oxygen are consumed by the resistance load, and the negative pressure is maintained when the storage state is shifted to the storage state. Therefore, there is a concern that air flows from the outside into the fuel electrode and the oxidant electrode, and hydrogen in the fuel electrode is consumed. On the other hand, in the stop storage start procedure shown in FIG. 6, the pressure drop at the time of storage is reduced, and it becomes possible to suppress the inflow of air from the outside.

[Second Embodiment]
FIG. 7 is a block diagram showing a configuration of a fuel cell system according to the second embodiment to which the present invention is applied. The fuel cell system of the present embodiment includes a fuel recycle blower 13 added to the configuration of the first embodiment, and the fuel gas supplied from the outlet of the fuel electrode 2 to the inlet side of the fuel electrode 2 is added. A recycling line is formed.

  The operation of the present embodiment having such a configuration is as follows. That is, when oxygen at the oxidizer electrode is consumed by hydrogen at the fuel electrode under a resistive load, if there is not enough hydrogen at the fuel electrode, carbon in the fuel electrode or oxidizer electrode is depleted due to hydrogen deficiency in the fuel electrode. Since there is a problem of corrosion, flowing hydrogen-containing gas for an arbitrary period after power generation is stopped until the gas sealing means of the fuel electrode is closed is effective for preventing deterioration and extending the remaining time of hydrogen during storage. It is.

  Therefore, when it is impossible or difficult to flow a gas containing hydrogen to the fuel electrode when power generation is stopped, the gas discharged from the fuel electrode is replaced with the gas at the fuel electrode by the fuel recycle blower 13 as shown in FIG. By circulating the hydrogen, it is possible to supply the hydrogen remaining in the pipe and the manifold to the fuel electrode.

  Therefore, according to the present embodiment, in addition to obtaining the same effect as that of the first embodiment, the fuel remaining in the piping and the manifold when power generation is stopped is supplied to the fuel electrode. It is possible to prevent deterioration of the electrode and the oxidant electrode, and to extend the remaining time of hydrogen during storage.

[Third Embodiment]
FIG. 8 is a block diagram showing a configuration of a fuel cell system according to a third embodiment to which the present invention is applied. The fuel cell system according to the present embodiment is configured such that the battery voltage monitoring means 14 is added to the configuration of the first embodiment to monitor the voltage when the fuel gas is introduced into the fuel electrode during the startup process. It is.

  FIG. 9 is a flowchart showing a stop storage start procedure by the fuel cell system of the present embodiment. The stop storage start procedure shown in FIG. 9 is the start procedure in which the fuel gas upstream enclosing means 8 and the fuel gas downstream enclosing means 9 are opened and the supply of fuel gas by the fuel gas supply means 5 is started (S121). The voltage monitoring means 14 monitors the voltage of the fuel cell main body 1 to detect whether or not a preset voltage is exceeded (S124).

  If the battery voltage does not exceed the set voltage (NO in S124), the oxidant gas upstream enclosing unit 10 and the oxidant gas downstream enclosing unit 11 are then opened, and the oxidant by the oxidant gas supply unit 6 is opened. By starting the supply of gas (S122), the fuel cell main body 1 is set in a power generation start state (S123). On the other hand, when the battery voltage exceeds the set voltage (YES in S124), the stop procedure is performed or an alarm is generated in the same manner as when the power generation stop command is issued (YES in S110). The stop procedure and storage state are the same as the stop storage start procedure of FIG.

  That is, when hydrogen is not present in the fuel electrode when the fuel is introduced, corrosion due to partial cell reaction occurs and the battery deteriorates. It is conceivable that the hydrogen does not exist in the fuel electrode because the sealing performance of the battery body is deteriorated, and air flows into the oxidant electrode or the fuel electrode from the outside and the hydrogen in the fuel electrode is consumed.

  Therefore, according to the present embodiment, in addition to obtaining the same effect as the first embodiment, it is possible to detect such a gas leak into the battery by monitoring the voltage at the start-up. In this case, since some measures can be implemented by stopping the plant or generating an alarm, it is possible to prevent further deterioration in battery performance.

[Fourth Embodiment]
FIG. 10 is a block diagram showing a configuration of a fuel cell system according to a fourth embodiment to which the present invention is applied. The fuel cell system of this embodiment is the same as that of the first embodiment except that the fuel gas downstream sealing means 9 and the oxidant gas downstream sealing means 11 are connected to the fuel gas downstream sealing check valve 15 and the oxidant gas that prevent backflow. This is a downstream sealed check valve 16.

  The operation of the present embodiment having such a configuration is as follows. In other words, if the gas sealing means is a solenoid valve, it must be closed when stopped, so normally closed that does not require power when stopping is selected. If the gas is lost, there is a concern that the solenoid valve is closed, the pressure of the supply gas is applied to the fuel cell, and the cell is damaged. On the other hand, in the present embodiment, the fuel gas downstream sealing means and the oxidant gas downstream sealing means are the check valves 15 and 16, thereby preventing excessive pressure from being applied to the battery. In addition, it is possible to prevent the inflow of air from the outside during stopping and storage.

  Therefore, according to the present embodiment, in addition to obtaining the same effect as that of the first embodiment, it is possible to obtain an effect of further reliably suppressing a decrease in fuel cell performance.

[Other Embodiments]
It should be noted that the present invention is not limited to the above-described embodiments, and various other variations can be implemented within the scope of the present invention. For example, the modified example of the first embodiment and the second to fourth embodiments can be selectively combined as appropriate, and in this case, a synergistic effect obtained by combining the effects described above can be obtained. It is done.

  Further, during storage, the fuel electrode and the oxidant electrode may be electrically short-circuited, or in the starting process, the fuel gas sealing means is opened and the fuel gas supply means supplies fuel gas to the fuel cell body. The fuel electrode and the oxidant electrode may be electrically short-circuited at the start. Further, both of these operations may be performed. In any case, by electrically short-circuiting the fuel electrode and the oxidizer electrode, even if air flows in from the outside at the time of stopping / storage, the voltage does not increase, and the battery performance caused by the potential gradient does not occur. Decline can be prevented.

The block diagram which shows the structure of the fuel cell system in 1st Embodiment to which this invention is applied. The flowchart which shows the stop storage starting procedure by the fuel cell system of FIG. The graph which shows the relationship between the number of start / stops in the stop storage start procedure by the method of this invention, and the stop storage start procedure by the method of a comparative example, and a voltage. The flowchart which shows the modification of the stop storage starting procedure by the fuel cell system of FIG. The flowchart which shows the other modification of the stop storage starting procedure by the fuel cell system of FIG. The flowchart which shows the other modification of the stop storage starting procedure by the fuel cell system of FIG. The block diagram which shows the structure of the fuel cell system in 2nd Embodiment to which this invention is applied. The block diagram which shows the structure of the fuel cell system in 3rd Embodiment to which this invention is applied. The flowchart which shows the stop storage starting procedure by the fuel cell system of FIG. The block diagram which shows the structure of the fuel cell system in 4th Embodiment to which this invention is applied. The figure which shows the flow of the electric current in the battery surface at the time of starting. The figure which shows the structure of the fuel cell to which the porous material separator is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell main body 2 ... Fuel electrode 3 ... Oxidant electrode 4 ... Battery cooling part 5 ... Fuel gas supply means 6 ... Oxidant gas supply means 7 ... Coolant water pump 8 ... Fuel gas upstream enclosure means 9 ... Fuel gas downstream enclosure Means 10 ... Oxidant gas upstream sealing means 11 ... Oxidant gas downstream sealing means 12 ... Plant control unit 13 ... Fuel recycling blower 14 ... Battery voltage monitoring means 15 ... Fuel gas downstream sealing check valve 16 ... Oxidant gas downstream sealing reverse Stop valve 31 ... Electrode 32 ... Fuel gas channel porous material separator 33 ... Oxidant gas channel porous material separator 34 ... Coolant channel porous material separator

Claims (10)

A fuel cell body having a fuel electrode, an oxidant electrode, a fuel gas channel, an oxidant gas channel, and a coolant channel, fuel gas supply means for supplying fuel gas to the fuel cell body, and the fuel cell body An oxidant gas supply means for supplying an oxidant gas to the fuel cell, a fuel gas sealing means for sealing the fuel gas in the fuel cell body by opening and closing the upstream and downstream sides of the fuel gas system of the fuel cell body, and an oxidation of the fuel cell body A method for stopping, storing, and starting a fuel cell system including an oxidant gas sealing means for sealing an oxidant gas in a fuel cell main body by opening and closing upstream and downstream of the agent gas system,
As a separator constituting the fuel gas channel, the oxidant gas channel, and the coolant channel, using a separator made of a porous material,
In the stopping process, the fuel gas sealing means and the oxidant gas sealing means are closed in a state where supply of the fuel gas and the oxidant gas by the fuel gas supply means and the oxidant gas supply means is stopped, and the fuel electrode is closed. Leaving the fuel gas,
During storage, the fuel gas sealing means and the oxidant gas sealing means are kept closed, and the fuel gas remains in the fuel electrode,
In the start-up process, after the fuel gas sealing means is opened and the supply of fuel gas to the fuel cell body by the fuel gas supply means is started, the oxidant gas sealing means is opened and the fuel cell by the oxidant gas supply means A stop storage start method for a fuel cell system, wherein supply of an oxidant gas to a main body is started, and supply of the oxidant gas is started in a state where the fuel gas is present in the fuel electrode. In stopping the process, in a state of closing the oxidant gas filled unit and the fuel gas filled unit, the oxygen present in the oxidant electrode to claim 1, characterized in that consumed in the hydrogen present in the fuel electrode The stop storage start method of the described fuel cell system. In the stopping process, after closing only the oxidant gas sealing means and opening the fuel gas sealing means, oxygen present in the oxidant electrode is consumed by hydrogen present in the fuel electrode, and then fuel gas sealing is performed. The method of stopping and starting the fuel cell system according to claim 1, wherein the means is closed. In the stopping process, after the fuel gas sealing means and the oxidant gas sealing means are opened, oxygen present in the oxidizer electrode is consumed by hydrogen present in the fuel electrode, and then the fuel gas sealing means and the oxidizer are oxidized. The method for stopping and starting the fuel cell system according to claim 1, wherein the agent gas sealing means is closed. The fuel cell system according to any one of claims 2 to 4, characterized in that connecting a resistive load of oxygen present in the oxidant electrode in order to consume hydrogen present in the fuel electrode Stop storage start method. In the stopping process, before the fuel gas sealing means is closed, the oxygen-containing gas is removed from the fuel electrode during an arbitrary period during which oxygen present in the oxidizer electrode is consumed by hydrogen present in the fuel electrode. The stop storage activation method for a fuel cell system according to claim 3 or 4 , wherein the fuel cell system is stored and activated. In the starting process, when the supply of fuel gas to the fuel cell main body by the fuel gas supply means is started, the voltage of the fuel cell main body is monitored to detect whether or not a preset voltage is exceeded, 2. The fuel cell system stop storage start method according to claim 1, wherein when the set voltage is exceeded, the fuel cell main body is stopped or an alarm is generated. During storage, stopped storage method of starting a fuel cell system according to claim 1, characterized in that for electrically short-circuiting the said fuel electrode the oxidant electrode. In the start-up process, the fuel gas sealing means is opened, and the fuel electrode and the oxidant electrode are electrically short-circuited when the fuel gas supply means starts supplying fuel gas to the fuel cell main body. The stop storage start method of the fuel cell system according to claim 1 . A fuel cell body having a fuel electrode, an oxidant electrode, a fuel gas channel, an oxidant gas channel, and a coolant channel, fuel gas supply means for supplying fuel gas to the fuel cell body, and the fuel cell body An oxidant gas supply means for supplying an oxidant gas to the fuel cell, a fuel gas sealing means for sealing the fuel gas in the fuel cell body by opening and closing the upstream and downstream sides of the fuel gas system of the fuel cell body, and an oxidation of the fuel cell body A program for stopping, storing, and starting a fuel cell system having an oxidant gas sealing means for sealing an oxidant gas in a fuel cell body by opening and closing upstream and downstream of the oxidant gas system,
When the fuel cell main body uses a separator made of a porous material as a separator constituting the fuel gas flow path, the oxidant gas flow path, and the coolant flow path,
In the stopping process, the fuel gas sealing means and the oxidant gas sealing means are closed in a state where supply of the fuel gas and the oxidant gas by the fuel gas supply means and the oxidant gas supply means is stopped, and the fuel electrode is closed. A function of remaining the fuel gas;
A function of keeping the fuel gas enclosing means and the oxidant gas enclosing means in a closed state during storage and keeping the fuel gas remaining in the fuel electrode;
In the start-up process, after the fuel gas sealing means is opened and the supply of fuel gas to the fuel cell body by the fuel gas supply means is started, the oxidant gas sealing means is opened and the fuel cell by the oxidant gas supply means Stopping storage activation of a fuel cell system, wherein the computer realizes a function of starting supply of oxidant gas to the main body and starting supply of the oxidant gas in a state where the fuel gas is present in the fuel electrode program.

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