JP2009158120A - FUEL CELL SYSTEM, OPERATION STOP METHOD, AND ITS START-UP METHOD - Google Patents

Abstract

An oxidant gas and a fuel gas in a oxidant gas flow path can be reliably replaced in a short time.
A fuel cell system (10) includes a fuel cell stack (12), an oxidant gas supply device (14) for supplying an oxidant gas to the fuel cell stack (12), a fuel gas to the fuel cell stack (12), and an operation. When stopped, the fuel gas supply device 16 capable of supplying the fuel gas to the oxidant gas passage 34, the decompression device 18 for sucking the oxidant gas passage 34 and the fuel gas passage 36, and the decompression device 18 And a dilution device 20 for diluting the fuel gas sucked in with air.
[Selection] Figure 1

Description

  The present invention has an oxidant gas flow path for supplying an oxidant gas to the cathode side electrode and a fuel gas flow path for supplying a fuel gas to the anode side electrode, and an electrochemical reaction between the oxidant gas and the fuel gas. The present invention relates to a fuel cell system including a fuel cell for generating power, a method for stopping operation thereof, and a method for starting the same.

  A fuel cell supplies a fuel gas (mainly hydrogen-containing gas) and an oxidant gas (mainly oxygen-containing gas) to the anode-side electrode and the cathode-side electrode and causes them to react electrochemically. It is a system that obtains electrical energy.

  For example, a polymer electrolyte fuel cell includes a power generation cell in which an electrolyte membrane / electrode structure provided with an anode side electrode and a cathode side electrode is sandwiched between separators on both sides of an electrolyte membrane made of a polymer ion exchange membrane. ing. This type of power generation cell is normally used as a fuel cell stack by alternately laminating a predetermined number of electrolyte membrane / electrode structures and separators.

  In this type of fuel cell, when power generation (operation) is stopped, supply of fuel gas and oxidant gas to the fuel cell is stopped, but the fuel gas remains on the anode side electrode, while the cathode side The oxidant gas remains on the electrode. For this reason, there is a problem that the cathode side is held at a high potential while the fuel cell is stopped, and the electrode catalyst layer is deteriorated. Therefore, for example, a method of forcibly purging the fuel gas remaining in the anode side electrode with an inert gas such as air or nitrogen is performed.

  However, while the fuel cell is stopped for a long time, air also enters the anode side electrode, and air exists in the cathode side electrode and the anode side electrode. When the fuel cell is started in this state, when the supply of fuel gas to the anode side electrode is started, in particular, the cathode side electrode tends to be at a high potential. As a result, there is a problem that the power generation performance is lowered due to the performance deterioration of the electrode catalyst layer of the anode side electrode (Patent Document 1).

  For this reason, for example, in the method for stopping a fuel cell power plant disclosed in Patent Document 2, after the load is disconnected from the fuel cell and the supply of the oxidant gas to the oxidant gas flow path is stopped, the oxidant gas By supplying the fuel gas to the flow path, the oxidant gas flow path and the fuel gas flow path are filled with the fuel gas.

JP-T-2006-507647 US Pat. No. 7,141,324

  However, in Patent Document 2 described above, it takes a relatively long time to replace the oxidant gas remaining in the oxidant gas flow path with the fuel gas when the operation of the fuel cell is stopped. As a result, it takes a considerable amount of time before the operation of the fuel cell is completely stopped, and there is a problem that an efficient operation stop process is not performed.

  The present invention solves this type of problem, and the replacement process of the oxidant gas and the fuel gas in the oxidant gas flow path can be performed reliably in a short time, and the fuel cell operation stop process and It is an object of the present invention to provide a fuel cell system capable of efficiently performing a starting process, a method for stopping the operation thereof, and a starting method thereof.

  The present invention has an oxidant gas flow path for supplying an oxidant gas to the cathode side electrode and a fuel gas flow path for supplying a fuel gas to the anode side electrode, and an electrochemical reaction between the oxidant gas and the fuel gas. The present invention relates to a fuel cell system including a fuel cell for generating power.

  The fuel cell system supplies a fuel gas to a fuel gas flow channel, and sucks at least the oxidant gas flow channel, a fuel gas supply device capable of supplying the fuel gas to the oxidant gas flow channel when operation is stopped. A pressure reducing device and a dilution device for diluting the fuel gas sucked by the pressure reducing device with air are provided.

  Moreover, it is preferable that a decompression device is individually provided with the 1st decompression pump which attracts | sucks an oxidizing gas flow path, and the 2nd decompression pump which attracts | sucks a fuel gas flow path.

  Furthermore, the present invention has an oxidant gas flow path for supplying an oxidant gas to the cathode side electrode and a fuel gas flow path for supplying a fuel gas to the anode side electrode, and the oxidant gas and the fuel gas electrochemical The present invention relates to a method for stopping operation of a fuel cell system including a fuel cell that generates electricity by reaction.

  In this operation stop method, the step of stopping the power supply from the fuel cell to the outside, the supply of the oxidant gas to the oxidant gas channel, and the supply of the fuel gas to the fuel gas channel are stopped. A step of sucking at least the oxidant gas flow path to depressurize the oxidant gas flow path, supplying at least the fuel gas to the oxidant gas flow path, and the oxidant gas flow path and the fuel. Filling the gas flow path with the fuel gas.

  Furthermore, the present invention has an oxidant gas flow path for supplying an oxidant gas to the cathode side electrode and a fuel gas flow path for supplying a fuel gas to the anode side electrode. The present invention relates to a method for starting a fuel cell system that includes a fuel cell that generates electric power by a chemical reaction, and is shut down in a state where the oxidant gas channel and the fuel gas channel are filled with the fuel gas.

  In this starting method, at least the fuel gas remaining in the oxidant gas flow path is sucked to depressurize the oxidant gas flow path, the fuel gas is supplied to the fuel gas flow path, and the oxidant gas flow And supplying the oxidant gas to the road to generate power in the fuel cell.

  In the present invention, since the oxidant gas flow path is sucked through the decompression device and the oxidant gas flow path is depressurized, a desired gas can be quickly and reliably replaced in the oxidant gas flow path. . Moreover, when the fuel gas remains in the oxidant gas flow path, the fuel gas sucked by the decompression device is diluted with air through the dilution device. Therefore, the fuel gas is not directly discharged to the outside, and the exhaust gas treatment can be performed satisfactorily.

  In the present invention, since at least the oxidant gas flow path is sucked to depressurize the oxidant gas flow path, and then fuel gas is introduced into the oxidant gas flow path, the oxidant gas flow path and The fuel gas flow path is filled with the fuel gas in a short time. For this reason, the fuel cell operation stop process is performed promptly and reliably, and the cathode side electrode does not become a high potential, and it is possible to satisfactorily suppress a decrease in power generation performance due to performance deterioration of the electrode catalyst layer. it can.

  Furthermore, in the present invention, at least the fuel gas remaining in the oxidant gas flow path is sucked and the oxidant gas flow path is depressurized, so that the oxidant gas can be quickly and reliably supplied to the oxidant gas. It becomes possible. As a result, the start-up process of the fuel cell is quickly and reliably performed.

  FIG. 1 is a schematic configuration diagram of a fuel cell system 10 according to a first embodiment of the present invention.

  The fuel cell system 10 includes a fuel cell stack 12, an oxidant gas supply device 14 for supplying an oxidant gas to the fuel cell stack 12, a fuel gas supply device 16 for supplying a fuel gas to the fuel cell stack 12, A decompressor 18 for sucking an oxidant gas passage 34 and a fuel gas passage 36 (to be described later), a diluter 20 for diluting the fuel gas with air, and a controller 21 for controlling the entire fuel cell system 10 are provided.

  The fuel cell stack 12 is configured by stacking a plurality of fuel cells 22. Each fuel cell 22 includes an electrolyte membrane / electrode structure 30 in which a solid polymer electrolyte membrane 24 is sandwiched between a cathode side electrode 26 and an anode side electrode 28. The electrolyte membrane / electrode structure 30 is paired with a pair of separators 32a, Hold by 32b. Between the electrolyte membrane / electrode structure 30 and the separator 32a, an oxidant gas channel 34 for supplying an oxidant gas to the cathode side electrode 26 is formed, and the electrolyte membrane / electrode structure 30 and the separator 32b are formed. A fuel gas passage 36 for supplying fuel gas to the anode side electrode 28 is formed between the two.

  At one end in the stacking direction of the fuel cell stack 12, an oxidant gas inlet communication hole 38a for supplying an oxidant gas such as air (oxygen-containing gas) to the oxidant gas flow path 34, and a fuel such as a hydrogen-containing gas A fuel gas inlet communication hole 40 a for supplying gas to the fuel gas flow path 36 is formed. At the other end in the stacking direction of the fuel cell stack 12, an oxidant gas outlet communication hole 38 b for discharging the oxidant gas from the oxidant gas flow path 34 and a fuel gas for discharging from the fuel gas flow path 36 are provided. A fuel gas outlet communication hole 40b is formed.

  The oxidant gas supply device 14 includes an air pump 42 that compresses and supplies air from the atmosphere, and the air pump 42 is disposed in the air supply flow path 44. An air filter 46 is disposed in the air supply channel 44 on the upstream side of the air pump 42. The air supply channel 44 communicates with the oxidant gas inlet communication hole 38 a of the fuel cell stack 12, and a dilution channel 48 is branched from the downstream side of the air pump 42, and the dilution channel 48 is connected to the dilution device 20. The Although not shown, a humidifier is disposed between the downstream of the air pump 42 and the oxidant gas inlet communication hole 38a.

  The oxidant gas supply device 14 includes an air discharge channel 50 that communicates with the oxidant gas outlet communication hole 38b. The air discharge channel 50 is connected to the dilution device 20.

  The fuel gas supply device 16 includes a hydrogen tank 52 that stores high-pressure hydrogen (hydrogen-containing gas), and the hydrogen tank 52 communicates with the fuel gas inlet communication hole 40 a of the fuel cell stack 12 via the hydrogen supply flow path 54. To do. The hydrogen supply channel 54 is provided with a regulator 56 and an ejector 58, and the downstream of the ejector 58 and the air supply channel 44 can communicate with each other via a branch channel 59.

  An off gas passage 60 communicates with the fuel gas outlet communication hole 40 b and a hydrogen circulation passage 62 communicates with the off gas passage 60. The off-gas flow path 60 is connected to the diluting device 20, while the hydrogen circulation path 62 is connected to the ejector 58.

  The ejector 58 supplies the hydrogen gas supplied from the hydrogen tank 52 to the fuel cell stack 12 through the hydrogen supply flow path 54, and exhaust gas containing unused hydrogen gas that has not been used in the fuel cell stack 12. Then, the gas is sucked from the hydrogen circulation path 62 and supplied again as fuel gas to the fuel cell stack 12.

  The decompression device 18 individually includes a first decompression pump 66 a that sucks the oxidant gas passage 34 and a second decompression pump 66 b that sucks the fuel gas passage 36. The first pressure reducing pump 66a is disposed in the first pressure reducing flow path 68a, and the first pressure reducing flow path 68a is connected to the air discharge flow path 50 and the diluting device 20. The second decompression pump 66b is disposed in the second decompression flow path 68b, and the second decompression flow path 68b is connected to the off-gas flow path 60 and the diluting device 20.

  The fuel cell system 10 is provided with a first on-off valve 70a to a tenth on-off valve 70j. Specifically, the first opening / closing valve 70 a is disposed in the branch flow path 59, and the second opening / closing valve 70 b is disposed in the air supply flow path 44 so as to be located upstream of the branch flow path 59. The third on-off valve 70 c is disposed in the hydrogen supply channel 54 between the regulator 56 and the ejector 58.

  The fourth opening / closing valve 70d is disposed in the vicinity of the fuel gas outlet communication hole 40b of the off gas passage 60, while the fifth opening / closing valve 70e is located in the vicinity of the diluting device 20 in the off gas passage 60. Arranged. The sixth on-off valve 70f is disposed in the air discharge channel 50 in the vicinity of the oxidant gas outlet communication hole 38b, and the seventh on-off valve 70g is in the vicinity of the dilution device 20 in the air discharge channel 50. It arranges (positioned downstream of the 1st decompression flow path 68a).

  The eighth open / close valve 70h is disposed upstream of the first pressure reducing pump 66a in the first pressure reducing flow path 68a, while the ninth open / close valve 70i is disposed in the second pressure reducing flow path 68b of the second pressure reducing pump 66b. Located upstream. The tenth open / close valve 70j is disposed in the dilution flow path 48.

  In the air supply channel 44, a first pressure sensor 72a is disposed between the second opening / closing valve 70b and the oxidant gas inlet communication hole 38a. In the hydrogen supply channel 54, a second pressure sensor 72b is disposed in the vicinity of the fuel gas inlet communication hole 40a. The first pressure sensor 72 a detects the pressure in the oxidant gas flow path 34, and the second pressure sensor 72 b detects the pressure in the fuel gas flow path 36.

  For example, a load 74 such as a drive motor is provided in the fuel cell stack 12 via a switch 76 so that it can be electrically disconnected and connected.

  Regarding the operation of the fuel cell system 10 configured as described above, in accordance with the start-up method and the operation stop method according to the first embodiment of the present invention, according to the flowchart shown in FIG. 2 and the timing chart shown in FIG. This will be described below.

  In the fuel cell system 10, as will be described later, the oxidant gas flow paths 34 and the fuel gas flow paths 36 of the fuel cell stack 12 are filled with the fuel gas in a stopped state. For this reason, when the fuel cell system 10 is started, first, the oxidant gas flow path 34 and the fuel gas flow path 36 are decompressed (step S1).

  Specifically, as shown in FIGS. 3 and 4, the first on-off valve 70a to the third on-off valve 70c, the fifth on-off valve 70e, and the seventh on-off valve 70g are closed, while the fourth on-off valve 70d, The sixth opening / closing valve 70f and the eighth opening / closing valve 70h to the tenth opening / closing valve 70j are opened. In this state, the first decompression pump 66a and the second decompression pump 66b constituting the decompression device 18 are driven, and the air pump 42 constituting the oxidant gas supply device 14 is simultaneously driven.

  The first decompression pump 66a communicates with the oxidant gas flow path 34, and the oxidant gas flow path 34 is sucked. Accordingly, the fuel gas remaining in the oxidant gas flow path 34 is sucked by the first pressure reduction pump 66a and discharged to the diluting device 20, so that the oxidant gas flow path 34 is depressurized. The reduced pressure state of the oxidant gas flow path 34 is detected by the first pressure sensor 72a.

  On the other hand, the second decompression pump 66 b sucks the fuel gas remaining in the fuel gas flow path 36 and discharges the fuel gas to the dilution device 20. Thereby, the fuel gas flow path 36 is decompressed. The reduced pressure state of the fuel gas passage 36 is detected by the second pressure sensor 72b.

  Further, external air is supplied from the dilution flow path 48 to the dilution device 20 via the air pump 42. For this reason, in the diluting device 20, the fuel gas sucked from the oxidant gas channel 34 and the fuel gas channel 36 is sufficiently diluted with air and then discharged to the outside.

  After the oxidant gas flow path 34 and the fuel gas flow path 36 reach a predetermined pressure reduction state, the pressure reduction is stopped (step S2) and held for a predetermined time. This decompression stop state is maintained by closing the eighth on-off valve 70h to the tenth on-off valve 70j as shown in FIGS.

  Next, the process proceeds to step S <b> 3 and fuel gas is supplied to each fuel gas flow path 36 of the fuel cell stack 12. Then, after a predetermined time has elapsed since the start of the supply of the fuel gas, the supply of the oxidant gas to each oxidant gas flow path 34 is started (step S4).

  Specifically, as shown in FIGS. 3 and 6, when the time T elapses after the third on-off valve 70c is opened, the second on-off valve 70b and the seventh on-off valve 70g are opened, The 5 on-off valve 70e is opened intermittently (or only by a predetermined opening).

  Accordingly, first, the fuel gas (hydrogen gas) is supplied from the hydrogen tank 52 to the hydrogen supply channel 54. The fuel gas is decompressed by the regulator 56 and then supplied to each fuel gas flow path 36 of the fuel cell stack 12. The fuel gas discharged from the fuel gas flow path 36 is sucked into the ejector 58 through the hydrogen circulation path 62 and supplied again to the fuel gas flow path 36 from the hydrogen supply flow path 54.

  Thereafter, since the air pump 42 is driven, air (oxidant gas) is supplied from the air supply channel 44 to each oxidant gas channel 34 of the fuel cell stack 12. The air discharged from the oxidant gas flow path 34 is sent to the dilution device 20.

  Therefore, the switch 76 is closed, and the load 74 is electrically connected to the fuel cell stack 12. Thereby, the power generation by the fuel cell stack 12 is started (step S5).

  During this power generation, the oxidant gas is sent to the oxidant gas flow path 34 of each fuel cell 22 and is supplied along each cathode side electrode 26. On the other hand, the fuel gas is supplied to each fuel gas flow path 36 of the fuel cell 22 and supplied along each anode side electrode 28. For this reason, electric power is generated by the electrochemical reaction between the air supplied to the cathode side electrode 26 and the fuel gas supplied to the anode side electrode 28.

  When power generation by the fuel cell stack 12 is stopped (step S6), the switch 76 is opened, so that the fuel cell stack 12 is electrically disconnected from the load 74. For this reason, the power supply from the fuel cell stack 12 to the outside is stopped. On the other hand, as shown in FIGS. 3 and 7, the second on-off valve 70b and the third on-off valve 70c are closed, and the supply of air and fuel gas to the fuel cell stack 12 is stopped.

  Furthermore, it progresses to step S7 and the pressure reduction process of the oxidant gas flow path 34 and the fuel gas flow path 36 is performed. During this decompression process, as shown in FIGS. 3 and 8, the fifth on-off valve 70e and the seventh on-off valve 70g are closed, while the eighth on-off valve 70h and the ninth on-off valve 70i are opened.

  Therefore, the oxidant gas flow path 34 is sucked under the action of the first pressure reducing pump 66a, and the oxidant gas remaining in the oxidant gas flow path 34 is discharged to the diluting device 20, whereby the oxidant gas The flow path 34 is depressurized. Further, under the action of the second pressure reducing pump 66b, the fuel gas passage 36 is sucked, and the fuel gas remaining in the fuel gas passage 36 is discharged to the diluting device 20, whereby the fuel gas passage 36 is Depressurized. At this time, since the air remaining in the oxidant gas flow path 34 is introduced into the dilution device 20, the fuel gas discharged from the fuel gas flow path 36 can be diluted well.

  When the oxidant gas flow path 34 and the fuel gas flow path 36 reach a predetermined pressure reduction state, the pressure reduction process is stopped (step S8). In step S8, as shown in FIGS. 3 and 5, the eighth on-off valve 70h and the ninth on-off valve 70i are closed. As a result, the oxidant gas passage 34 and the fuel gas passage 36 are maintained in a predetermined reduced pressure state, and a hydrogen purge process is performed after a predetermined time has elapsed.

  Specifically, as shown in FIGS. 3 and 9, the fourth on-off valve 70d and the sixth on-off valve 70f are closed, and first, the third on-off valve 70c is opened. Therefore, the fuel gas is supplied from the hydrogen tank 52 to the hydrogen supply channel 54, and this fuel gas is filled in each fuel gas channel 36 of the fuel cell stack 12 (step S9).

  After the third opening / closing valve 70c is opened, when the predetermined time T has elapsed, the first opening / closing valve 70a is opened. Accordingly, a part of the fuel gas led out from the hydrogen tank 52 is branched into the branch flow path 59 and filled in each oxidant gas flow path 34 of the fuel cell stack 12 (step S10).

  Then, after the fuel gas pressure filled in the fuel gas flow path 36 and the oxidant gas flow path 34 reaches atmospheric pressure, the first open / close valve 70a and the third open / close valve 70c are closed, whereby the fuel cell. The entire system 10 is stopped (all stopped) (step S11).

  In this case, in the first embodiment, when the operation of the fuel cell system 10 is stopped, the oxidant gas flow path 34 is depressurized via the first depressurization pump 66a constituting the depressurization device 18, as shown in FIG. At the same time, the fuel gas passage 36 is decompressed via the second decompression pump 66b. Next, after the fuel gas is supplied from the hydrogen tank 52 to the fuel gas flow path 36, the fuel gas is supplied to the oxidant gas flow path 34 when a predetermined time T has elapsed.

  At that time, the fuel gas flow path 36 and the oxidant gas flow path 34 are maintained in a reduced pressure state, and the fuel gas is forcibly sucked. Is quickly filled with the fuel gas. For this reason, the effect that the operation stop process of the fuel cell system 10 is quickly and reliably performed is obtained.

  Moreover, after the fuel gas is introduced into the fuel gas passage 36, the fuel gas is introduced into the oxidant gas passage 34. Thereby, in particular, an increase in potential of the cathode electrode 26 can be prevented, and each fuel cell 22 can satisfactorily suppress a decrease in power generation performance due to performance deterioration of the electrode catalyst layer.

  In the first embodiment, when the fuel cell system 10 is started in a state where the oxidant gas flow path 34 and the fuel gas flow path 36 are filled with the fuel gas, first, the oxidant gas flow path 34. The fuel gas passage 36 is subjected to a decompression process (see FIG. 4). Therefore, the fuel gas can be supplied to the fuel gas passage 36 quickly and reliably, and the air can be supplied to the oxidant gas passage 34 quickly and reliably. For this reason, there is an effect that the startup process of the fuel cell stack 12 is efficiently started.

  Further, after the decompression process, first, the fuel gas is supplied to the fuel gas passage 36 for a predetermined time T, and then the air is supplied to the oxidant gas passage 34. Thereby, the cathode side electrode 26 does not become a high potential, and it becomes possible to satisfactorily suppress the performance deterioration of the electrode catalyst layer.

  FIG. 10 is a schematic configuration diagram of a fuel cell system 80 according to the second embodiment of the present invention. Note that the same components as those of the fuel cell system 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The fuel cell system 80 includes a decompression device 82, and the decompression device 82 includes a decompression pump 66 that sucks the oxidant gas flow path 34.

  The fuel cell system 80 includes a first opening / closing valve 84a to a tenth opening / closing valve 84j. The first open / close valve 84 a is disposed in the branch flow path 59, and the second open / close valve 84 b is disposed in the air supply flow path 44. The third open / close valve 84c is disposed in the hydrogen supply flow path 54 in the vicinity of the fuel gas inlet communication hole 40a, while the fourth open / close valve 84d is provided in the hydrogen supply flow path 54 with a regulator 56 and an ejector 58. It is located between.

  The fifth on-off valve 84e is disposed in the off-gas passage 60 in the vicinity of the fuel gas outlet communication hole 40b, while the sixth on-off valve 84f is in the off-gas passage 60 in the vicinity of the diluting device 20. Arranged. The seventh opening / closing valve 84g is disposed in the air discharge passage 50 in the vicinity of the oxidant gas outlet communication hole 38b, and the eighth opening / closing valve 84h is in the vicinity of the dilution device 20 in the air discharge passage 50. It is arranged in the position. The ninth opening / closing valve 84 i is disposed in the decompression flow path 68, and the tenth opening / closing valve 84 j is disposed in the dilution flow path 48.

  The operation of the fuel cell system 80 configured as described above will be described below along the flowchart shown in FIG. 11 and the timing chart shown in FIG.

  In the fuel cell system 80, as in the fuel cell system 10 described above, the fuel cell system 80 is stopped in a state where the oxidant gas flow path 34 and the fuel gas flow path 36 are filled with fuel gas. For this reason, at the time of start-up, first, the pressure reducing process of the oxidant gas flow path 34 is performed (step S21).

  As shown in FIGS. 12 and 13, the first on-off valve 84a to the sixth on-off valve 84f and the eighth on-off valve 84h are closed, while the seventh on-off valve 84g, the ninth on-off valve 84i, and the tenth on-off valve 84j. Is released. In this state, the decompression pump 66 and the air pump 42 are driven simultaneously.

  As a result, the oxidant gas passage 34 is sucked, and the hydrogen gas remaining in the oxidant gas passage 34 is discharged to the diluting device 20 under the suction action of the decompression pump 66. In addition, external air is introduced into the diluting device 20 via an air pump 42. Accordingly, in the diluting device 20, the fuel gas is diluted and then released to the outside, while the oxidant gas flow path 34 reaches a predetermined reduced pressure state.

  And after pressure reduction is stopped (step S22), it hold | maintains only for predetermined time. When this decompression is stopped, as shown in FIGS. 12 and 14, the ninth opening / closing valve 84 i and the tenth opening / closing valve 84 j are closed, thereby closing the entrance / exit of the oxidant gas flow path 34.

  Next, the process proceeds to step S23, and the supply of fuel gas to the fuel gas channel 36 is started. As shown in FIGS. 12 and 15, first, the third opening / closing valve 84c to the fifth opening / closing valve 84e are opened, and the sixth opening / closing valve 84f is intermittently opened / closed (or adjusted to a predetermined opening). . Therefore, the fuel gas is supplied from the hydrogen tank 52 to each fuel gas flow path 36 of the fuel cell stack 12 via the hydrogen supply flow path 54, and the fuel gas discharged from the fuel gas flow path 36 is supplied with hydrogen circulation. The fuel gas passage 36 is supplied again via the passage 62.

  After a predetermined time T has elapsed, the second opening / closing valve 84b and the eighth opening / closing valve 84h are opened. Therefore, air is sent to each oxidant gas flow path 34 of the fuel cell stack 12 under the action of the air pump 42 (step S24). The air released from the oxidant gas flow path 34 is discharged to the dilution device 20. In this state, the switch 76 is closed and the load 74 is electrically connected to the fuel cell stack 12, whereby the power generation by the fuel cell stack 12 is started (step S25).

  Further, as shown in FIGS. 12 and 16, when the power generation of the fuel cell system 10 is stopped (step S <b> 26), the process proceeds to step S <b> 27 and pressure reduction of the oxidant gas flow path 34 is started. In this decompression process, as shown in FIGS. 12 and 17, the fifth on-off valve 84e, the sixth on-off valve 84f, and the eighth on-off valve 84h are closed, and the ninth on-off valve 84i is opened.

  For this reason, the oxidant gas flow path 34 is sucked under the action of the decompression pump 66, and the air remaining in the oxidant gas flow path 34 is discharged to the diluting device 20, whereby the oxidant gas flow path 34. Is depressurized. When the oxidant gas flow path 34 reaches a predetermined reduced pressure state, the reduced pressure stop is performed as shown in FIGS. 12 and 14 (step S28).

  Then, after being held for a predetermined time in a reduced pressure state, supply of fuel gas to the oxidant gas flow path 34 is started (step S29). Specifically, as shown in FIGS. 12 and 18, the seventh opening / closing valve 84g is closed, while the first opening / closing valve 84a and the fourth opening / closing valve 84d are opened. As a result, the fuel gas supplied from the hydrogen tank 52 is sucked into the oxidant gas passage 34 through the branch passage 59.

  Next, when the fuel gas pressure in the oxidant gas flow path 34 reaches atmospheric pressure, the entire operation of the fuel cell system 80 is stopped (step S30). In this state, the first on-off valve 84a to the tenth on-off valve 84j are all closed.

  In this case, in the second embodiment, when the operation of the fuel cell system 80 is stopped, the oxidant gas flow path 34 is decompressed and then the fuel gas is supplied to the oxidant gas flow path 34. For this reason, the filling process of the fuel gas into the oxidant gas flow path 34 is reliably performed in a short time. As a result, the same effect as that of the first embodiment can be obtained, for example, the operation stop process of the fuel cell system 80 can be performed quickly and reliably.

  Furthermore, in the second embodiment, when the fuel cell system 80 is started, first, the oxidant gas flow path 34 is decompressed and the fuel gas remaining in the oxidant gas flow path 34 is sucked, and then the oxidant Air is introduced into the gas flow path 34. Therefore, since the oxidant gas flow path 34 in the decompressed state is filled with air, the air can be filled quickly and reliably. For this reason, the effect similar to 1st Embodiment is acquired, such as starting of the fuel cell system 80 being started efficiently.

1 is a schematic configuration diagram of a fuel cell system according to a first embodiment of the present invention. It is a flowchart explaining the starting method and operation stop method which concern on the 1st Embodiment of this invention. 4 is a timing chart in the first embodiment. It is explanatory drawing at the time of pressure reduction of the said fuel cell system. It is explanatory drawing at the time of the decompression stop of the said fuel cell system. It is explanatory drawing at the time of the electric power generation of the said fuel cell system. It is explanatory drawing at the time of the electric power generation stop of the said fuel cell system. It is explanatory drawing at the time of pressure reduction of the said fuel cell system. It is explanatory drawing at the time of the hydrogen purge of the said fuel cell system. It is a schematic block diagram of the fuel cell system which concerns on the 2nd Embodiment of this invention. It is a flowchart explaining the starting method and driving | running method which concern on the 2nd Embodiment of this invention. It is a timing chart in the 2nd embodiment. It is explanatory drawing at the time of pressure reduction of the said fuel cell system. It is explanatory drawing at the time of the decompression stop of the said fuel cell system. It is explanatory drawing at the time of the electric power generation of the said fuel cell system. It is explanatory drawing at the time of the electric power generation stop of the said fuel cell system. It is explanatory drawing at the time of pressure reduction of the said fuel cell system. It is explanatory drawing at the time of the hydrogen purge of the said fuel cell system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 80 ... Fuel cell system 12 ... Fuel cell stack 14 ... Oxidant gas supply device 16 ... Fuel gas supply device 18 ... Decompression device 20 ... Dilution device 21 ... Controller 22 ... Fuel cell 24 ... Solid polymer electrolyte membrane 26 ... Cathode Side electrode 28 ... Anode side electrode 30 ... Electrolyte membrane / electrode structure 32a, 32b ... Separator 34 ... Oxidant gas channel 36 ... Fuel gas channel 38a ... Oxidant gas inlet communication hole 38b ... Oxidant gas outlet communication hole 40a ... fuel gas inlet communication hole 40b ... fuel gas outlet communication hole 42 ... air pump 44 ... air supply flow path 48 ... dilution flow path 50 ... air discharge flow path 52 ... hydrogen tank 54 ... hydrogen supply flow path 58 ... ejector 59 ... branch flow Path 60 ... Off gas flow path 62 ... Hydrogen circulation path 66, 66a, 66b ... Pressure reducing pumps 68, 68a, 68b ... Pressure reducing paths 70a-70j 84A～84j ... off valves 72a, 72b ... pressure sensor 82 ... decompressor

Claims (4)

A fuel cell having an oxidant gas flow path for supplying an oxidant gas to the cathode side electrode and a fuel gas flow path for supplying a fuel gas to the anode side electrode, and generating electric power by an electrochemical reaction of the oxidant gas and the fuel gas A fuel cell system comprising:
A fuel gas supply device capable of supplying the fuel gas to the fuel gas flow path and capable of supplying the fuel gas to the oxidant gas flow path when operation is stopped;
A pressure reducing device for sucking at least the oxidant gas flow path;
A dilution device for diluting the fuel gas sucked by the decompression device with air;
A fuel cell system comprising: 2. The fuel cell system according to claim 1, wherein the decompression device includes a first decompression pump that sucks the oxidant gas flow path,
A second decompression pump for sucking the fuel gas flow path;
A fuel cell system comprising: A fuel cell having an oxidant gas flow path for supplying an oxidant gas to the cathode side electrode and a fuel gas flow path for supplying a fuel gas to the anode side electrode, and generating electric power by an electrochemical reaction of the oxidant gas and the fuel gas A method for stopping operation of a fuel cell system comprising:
Stopping power supply from the fuel cell to the outside;
Stopping the supply of the oxidant gas to the oxidant gas flow path, and stopping the supply of the fuel gas to the fuel gas flow path;
Sucking at least the oxidant gas flow path and depressurizing the oxidant gas flow path; and
Supplying the fuel gas to at least the oxidant gas flow path, and filling the oxidant gas flow path and the fuel gas flow path with the fuel gas;
A method for stopping the operation of the fuel cell system. A fuel cell having an oxidant gas flow path for supplying an oxidant gas to the cathode side electrode and a fuel gas flow path for supplying a fuel gas to the anode side electrode, and generating electric power by an electrochemical reaction of the oxidant gas and the fuel gas A starting method of a fuel cell system, wherein the operation is stopped in a state where the oxidant gas flow path and the fuel gas flow path are filled with the fuel gas,
Sucking at least the fuel gas remaining in the oxidant gas flow path to depressurize the oxidant gas flow path;
Supplying the fuel gas to the fuel gas flow path and supplying the oxidant gas to the oxidant gas flow path to generate power in the fuel cell;
A starting method for a fuel cell system, comprising:

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