JP2005243291A - Fuel cell system - Google Patents

Abstract

To stably generate power by preventing flooding when reversing a gas flow supplied to a fuel cell.
A fuel cell system includes a first port 11 for introducing a gas into the fuel cell 1, a second port 12 for deriving the gas introduced into the fuel cell 1, and a branch flow for reversing the gas flow. Roads 16 and 19, shut-off valves SV1 to SV4, and three-way valves TV1 and TV2 are provided. This system introduces gas from the second port 12 to the fuel cell 1 and derives gas from the first port 11 by reversing the gas flow. This system includes a third port 13 for only deriving gas from the fuel cell 1 and a fifth shutoff valve SV5 for opening and closing the port 13. The fifth shutoff valve SV5 is opened only when the gas flow is reversed.
[Selection] Figure 2

Description

  The present invention relates to a fuel cell system including a fuel cell that supplies a predetermined gas to generate power.

  In general, a fuel cell includes a polymer electrolyte membrane that selectively transports hydrogen ions, and an anode and a cathode that are a pair of electrodes provided on both surfaces of the electrolyte membrane. Then, a fuel gas containing hydrogen and an oxidant gas containing oxygen are supplied to the fuel cell, and these gases are caused to react electrochemically to generate power and generate heat. . The fuel cell system includes the above-described fuel cell and a device for supplying fuel gas and oxidant gas as predetermined gases to the fuel cell.

  Here, it is known that water is condensed (flooding) in the fuel cell depending on certain conditions. When this flooding occurs, the condensed water hinders the gas supply to the electrode catalyst, causing a power generation failure in the fuel cell and degrading the cell performance. Therefore, techniques relating to flooding countermeasures are described in, for example, Patent Documents 1 and 2 below.

  In the fuel cell systems described in Patent Documents 1 and 2, by reversing (reversing) the gas flow in the gas flow path of the fuel cell, water accumulated in the gas flow path is temporarily removed and flooding is performed. Suppressed. Here, the reversal of the gas flow is performed by combining piping and a plurality of valves, and opening / closing and switching the valves as appropriate. The fuel cell system described in Patent Document 1 includes a shutoff valve provided corresponding to each of an inlet and an outlet of the fuel cell as a valve for reversing the gas flow, and these are connected to the inlet and the outlet via a pipe. ing.

Japanese Patent Laid-Open No. 2001-210341 (page 2-5, FIGS. 1 and 3) Japanese Patent Laid-Open No. 2002-158023 (page 2-8, FIGS. 1, 3, 5, and 7)

  However, in the fuel cell systems described in Patent Documents 1 and 2, since the gas flow in the fuel cell stops at the moment when the gas flow is reversed, flooding occurs in the fuel cell at that moment, causing a voltage drop. There was a fear.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel cell system that can prevent the occurrence of flooding when the gas flow supplied to the fuel cell is reversed and can stably generate power. There is to do.

  In order to achieve the above object, a fuel cell system according to a first aspect of the present invention includes a first port provided in the fuel cell, a second port provided in the fuel cell, and a first port in the fuel cell. A gas passage connecting the first port and the second port, a third port provided in the fuel cell and connected to the gas passage, a first gas supply passage connecting the gas source and the first port, and a first gas supply passage A first open / close valve that opens and closes, a first gas discharge passage that connects the first port and the exhaust gas port, a second open / close valve that opens and closes the first gas discharge passage, and a gas source and the second port connected The second gas supply channel, the third on-off valve for opening and closing the second gas supply channel, the second gas discharge channel connecting the second port and the exhaust gas port, and opening and closing the second gas discharge channel A fourth on-off valve, a third gas exhaust passage connecting the third port and the exhaust gas port, and a third gas exhaust And purpose that a fifth on-off valve for opening and closing the flow path.

  According to the configuration of the above invention, the first on-off valve and the fourth on-off valve are opened, and the second on-off valve and the third on-off valve are closed, so that the gas from the gas source flows through the first gas supply flow path. It is introduced into the fuel cell from one port. The introduced gas is used for power generation while passing through a gas passage in the fuel cell. The gas used for power generation is led out from the fuel cell through the second port, flows through the second gas discharge passage, and is discharged from the exhaust gas port. Here, in order to reverse the flow of the gas supplied to the fuel cell, the first on-off valve and the fourth on-off valve are closed and the second on-off valve and the fourth on-off valve are opened. The gas flows through the two gas supply channels and is introduced into the fuel cell from the second port. The introduced gas is used for power generation while passing through a gas passage in the fuel cell. The gas used for power generation is led out from the fuel cell through the first port, flows through the first gas discharge passage, and is discharged from the exhaust gas port. When this gas flow is reversed, the gas that passes through the gas passage in the fuel cell is also derived from the third port by opening and closing the fifth on-off valve, and flows through the third gas discharge passage to discharge the gas. Since the gas is discharged from the mouth, the gas flow does not stop in the gas passage in the fuel cell at the moment when the gas flow is reversed.

  In order to achieve the above object, a fuel cell system according to a second aspect of the present invention is the fuel cell system according to the first aspect, wherein the first port, the first gas supply flow path, and the first gas discharge flow are provided. A first three-way valve serving as a first on-off valve and a second on-off valve connected to the passage; a third on-off valve connected to the second port, the second gas supply channel, and the second gas discharge channel; The purpose is to provide a second three-way valve that also serves as a fourth on-off valve.

  According to the configuration of the above invention, in addition to the operation of the fuel cell system according to the first aspect, the first three-way valve serves as both the first on-off valve and the second on-off valve, so the number of components is reduced.

  In order to achieve the above object, a fuel cell system according to a third aspect of the present invention is the fuel cell system according to the first or second aspect, wherein a gas is introduced into the fuel cell from the first port and the second port. A first gas flow state derived only from the first port, a second gas flow state introduced into the fuel cell from the second port and derived only from the first port, and a gas introduced into the fuel cell from the first port and the second port And a third gas flow state derived from the third port, a fourth gas flow state introduced into the fuel cell through the first port and the second port and derived from the third port, and a gas into the fuel cell as the second port A first gas port and a fifth gas flow state led out from the third port, and the second gas passes through the third gas flow state, the fourth gas flow state, and the fifth gas flow state from the first gas flow state. The purpose is to switch to the flow state

  According to the configuration of the invention, in addition to the operation of the fuel cell system according to the first or second aspect of the invention, the gas flow state is switched to introduce gas from the first port into the fuel cell. Only, then gas is introduced into the fuel cell from the first port and led out from the second port and the third port, and then the gas is introduced into the fuel cell from the first port and the second port and led out from the third port Then, the gas is introduced into the fuel cell from the second port and led out from the first port and the third port, and finally the gas is introduced into the fuel cell from the second port and led out only from the first port. In this way, the gas flow is reversed with respect to the fuel cell, and at the time of the reversal, part of the gas is discharged from the gas passage in the fuel cell through the third port.

  According to the first aspect of the invention, the flow of the gas supplied to the fuel cell by appropriately switching the first on-off valve, the second on-off valve, the third on-off valve, the fourth on-off valve, and the fifth on-off valve. Can be reversed, and the occurrence of flooding during the reversal can be prevented, whereby stable power generation can be performed.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the configuration of the fuel cell system can be simplified.

  According to the third aspect of the present invention, it is possible to prevent the occurrence of flooding when reversing the gas flow supplied to the fuel cell, thereby enabling stable power generation.

[First Embodiment]
Hereinafter, a first embodiment of a fuel cell system according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration diagram of a fuel cell system. This fuel cell system includes a fuel cell 1, a first pipe 3 that supplies fuel gas containing hydrogen from a fuel gas source 31 to the fuel cell 1 via a reformer 2, and the fuel cell 1. On the other hand, a second pipe 4 for supplying an oxidant gas containing oxygen from an oxidant gas source 32 is provided. The fuel cell 1 includes a polymer electrolyte membrane that selectively transports hydrogen ions, and an anode and a cathode that are a pair of electrodes provided on both surfaces of the electrolyte membrane. In this fuel cell system, fuel gas and oxidant gas are supplied to the fuel cell 1 and these gases are reacted electrochemically to generate power and generate heat.

  FIG. 2 is a schematic diagram showing the configuration of the fuel cell 1 and the second pipe 4 that supplies the fuel cell 1 with an oxidant gas as a predetermined gas. The fuel cell 1 introduces the oxidant gas and introduces the oxidant gas in the same manner as the first port 11 used for deriving the oxidant gas after being used in the fuel cell 1. A second port 12 used for deriving the oxidant gas after being used, and a third port 13 used only for deriving the oxidant gas after being introduced into the fuel cell 1 Prepare.

  In the second pipe 4, the upstream flow path 14 is divided into two at the branch portion 15, and one of the first branch flow paths 16 communicates with the first port 11 of the fuel cell 1 and the downstream flow path 17. It leads to the junction 18. The other second branch flow path 19 divided by the branch portion 15 is connected to the second port 12 and the merge portion 18 of the fuel cell 1. The merging portion 18 is connected to the third port 13 of the fuel cell 1. An exhaust gas port 20 is provided in the downstream channel 17.

  Here, in the middle of the first branch flow path 16, a first shut valve SV1, a first three-way valve TV1, and a second shut valve SV2 are provided in this order from the upstream side. In the first three-way valve TV1, the first switching port 21a communicates with the output port 22a of the first shut valve SV1, the second switching port 21b communicates with the first port 11 of the fuel cell 1, and the third switching port 21c becomes the first. It leads to the input port 23a of the two-shut valve SV2. The input port 22b of the first shut valve SV1 communicates with the branching section 15, and the output port 23b of the second shut valve SV2 communicates with the merging section 18.

  A third shut valve SV3, a second three-way valve TV2, and a fourth shut valve SV4 are provided in the middle of the second branch flow path 19 in order from the upstream side. In the second three-way valve TV2, the first switching port 24a communicates with the output port 25a of the third shut valve SV3, the second switching port 24b communicates with the second port 12 of the fuel cell 1, and the third switching port 24c communicates with the second switching port 24c. It leads to the input port 26a of the 4-shut valve SV4. The input port 25b of the third shut valve SV3 communicates with the branching section 15, and the output port 26b of the fourth shut valve SV4 communicates with the merging section 18. The third port 13 of the fuel cell 1 is provided with a fifth shut valve SV5 as a fifth on-off valve of the present invention. The shut valves SV1 to SV5 and the three-way valves TV1 and TV2 are driven by electromagnets. In this embodiment, the first three-way valve TV1 described above constitutes a first three-way valve that also serves as the first on-off valve and the second on-off valve of the present invention. Further, the second three-way valve TV2 described above constitutes a second three-way valve that serves as the third on-off valve and the fourth on-off valve of the present invention.

  In this embodiment, the first gas supply flow path of the present invention is configured by the upstream flow path 14 and the first branch flow path 16 from the branch portion 15 to the first port 11. Further, the first branch flow path 16 from the first port 11 to the junction 18 and the downstream flow path 17 constitute the first gas discharge flow path of the present invention. On the other hand, the upstream side flow path 14 and the second branch flow path 19 from the branch portion 15 to the second port 12 constitute the second gas supply flow path of the present invention. The second branch flow path 19 from the second port 12 to the junction 18 and the downstream flow path 17 constitute the second gas discharge flow path of the present invention. Furthermore, the merged portion 18 from the third port 13 to the exhaust gas port 20 and the downstream flow path 17 constitute the third gas discharge flow path of the present invention. The flow of the oxidant gas is guided to the first port 11 by the shut valves SV1 to SV4, the three-way valves TV1 and TV2, and the branch flow paths 16 and 19, so that the oxidant gas is supplied from the first port 11 to the fuel. The oxidant gas is introduced into the battery 1 and led out from the second port 12. On the other hand, the flow of the oxidant gas is reversed in the opposite direction by the shut valves SV1 to SV4, the three-way valves TV1 and TV2, and the branch flow paths 16 and 19, so that the oxidant gas is fueled from the second port 12. The oxidant gas is introduced into the battery 1 and led out from the first port 11. In addition, the oxidant gas flow from the first port 11 to the fuel cell 1 is further reversed by the shut valves SV1 to SV4, the three-way valves TV1 and TV2, and the branch flow paths 16 and 19. The oxidant gas is introduced from the second port 12 and introduced. The fifth shut valve SV5 is opened only when the flow of the oxidant gas is reversed.

  As shown in FIG. 2, the shut valves SV <b> 1 to SV <b> 5 and the first and second three-way valves TV <b> 1 and TV <b> 2 are electrically connected to the controller 30. The controller 30 switches the shut valves SV1 to SV5 and the three-way valves TV1 and TV2 based on a predetermined control program in order to reverse the flow of the oxidant gas from the forward direction to the reverse direction and from the reverse direction to the forward direction. Control each one. That is, the controller 30 opens the first and fourth shut valves SV1 and SV4 and causes the second and third shut valves SV2 and SV3 to flow in order to flow the oxidant gas in the positive direction indicated by the bold arrows in FIG. Closed, opens between the first switching port 21a and the second switching port 21b of the first three-way valve TV1, and opens between the second switching port 24b and the third switching port 24c of the second three-way valve TV2. ing. On the other hand, the controller 30 opens the second and third shut valves SV2 and SV3, and opens the first and fourth shut valves SV1 and SV4 in order to flow the oxidant gas in the reverse direction indicated by the broken line arrow in FIG. Closed, opens between the second switching port 21b and the third switching port 21c of the first three-way valve TV1, and opens between the first switching port 24a and the second switching port 24b of the second three-way valve TV2. ing. The controller 30 opens the fifth shut valve SV5 when reversing the flow of the oxidant gas.

  The fuel cell system of this embodiment includes a first gas flow state in which an oxidant gas is introduced into the fuel cell 1 from the first port 11 and led out only from the second port 12, and an oxidant gas is introduced into the fuel cell 1 through the second port. The second gas flow state introduced from the first port 11 and led out only from the first port 11, and the third gas flow introduced into the fuel cell 1 from the first port 11 and led out from the second port 12 and the third port 13 A state, a fourth gas flow state in which an oxidant gas is introduced into the fuel cell 1 from the first port 11 and the second port 12 and led out from the third port 13, and an oxidant gas from the second port 12 to the fuel cell 1 The fifth gas flow state introduced and led out from the first port 11 and the third port 13 can be set. Then, the controller 30 switches the shut valves SV1 to SV5 from the first gas flow state to the second gas flow state through the third gas flow state, the fourth gas flow state, and the fifth gas flow state. Each three-way valve TV1, TV2 is controlled.

  As shown in FIG. 3, the fuel cell 1 includes a separator 5, a polymer electrolyte membrane 6, and an electrode 7 (anode and cathode) stacked on each other. The separator 5 is provided with an in-battery gas passage 8 that matches the shape and size of the electrode 7. The in-battery gas flow path 8 is provided with the first port 11, the second port 12, and the third port 13 described above.

  According to the fuel cell system of this embodiment described above, the gas flow state changes from the first gas flow state to the second gas flow state through the third gas flow state, the fourth gas flow state, and the fifth gas flow state. By switching, the oxidant gas is introduced into the fuel cell 1 from the first port 11 and is led out only from the second port 12. Next, oxidant gas is introduced into the fuel cell 1 from the first port 11 and is led out from the second port 12 and the third port 13. Next, oxidant gas is introduced into the fuel cell 1 from the first port 11 and the second port 12 and is led out from the third port 13. Next, oxidant gas is introduced into the fuel cell 1 from the second port 12 and is led out from the first port 11 and the third port 13. Finally, oxidant gas is introduced into the fuel cell 1 from the second port 12 and is led out only from the first port 11. In this way, the oxidant gas flow with respect to the fuel cell 1 is reversed, and part of the oxidant gas is discharged from the cell gas passage 8 through the third port 13 at the time of the reversal.

  When the oxidant gas flows in the positive direction by switching the gas flow state as described above, the gas is introduced into the fuel cell 1 from the first port 11 to generate power. The oxidant gas after being used for power generation is derived from the fuel cell 1 only through the second port 12. Here, the flow of the oxidant gas supplied to the fuel cell 1 is reversed by the shut valves SV1 to SV4, the three-way valves TV1 and TV2, and the branch passages 16 and 19, so that the gas flows into the second port. 12 is introduced into the fuel cell 1 to generate electricity. The oxidant gas after being used for power generation is derived from the fuel cell 1 only through the first port 11. When the flow of the oxidant gas is reversed, the gas is discharged from the fuel cell 1 through the third port 13 by opening the fifth shut valve SV5. For this reason, when the flow of the oxidant gas is reversed, the flow of the oxidant gas does not stop in the fuel cell 1. As a result, it is possible to prevent the occurrence of flooding when the flow of the oxidant gas supplied to the fuel cell 1 is reversed, so that the fuel cell 1 can perform stable power generation.

  In this embodiment, since the controller 30 controls the shut valves SV1 to SV5 and the three-way valves TV1 and TV2, the supply of the oxidant gas to the fuel cell 1 and the reversal of the flow of the oxidant gas are automatically performed. To be done. For this reason, generation of flooding in the fuel cell 1 and stabilization of power generation can be achieved unattended.

  In this embodiment, the first three-way valve TV1 corresponds to the introduction and derivation of the oxidant gas to the first port 11, and the second three-way valve corresponds to the oxidant gas introduction and derivation to the second port 12. TV2 is provided respectively. Accordingly, the two shut valves corresponding to the first port 11 also serve as the first three-way valve TV1, and the two shut valves corresponding to the second port 12 also serve as the second three-way valve TV2. The number of components of the fuel cell system is reduced. In this sense, the configuration of the fuel cell system can be simplified.

[Second Embodiment]
Next, a second embodiment embodying the fuel cell system of the present invention will be described in detail with reference to the drawings.

  In the second to third embodiments described below, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, different points will be mainly described. .

  As shown in FIG. 4, in this embodiment, the third port 13 in the fuel cell 1 is omitted, and the first, fourth, and fifth shut valves SV1, SV4, SV5 are omitted. The configuration is different. Further, in this embodiment, the first three-way valve TV1 is directly connected to the first port 11 and the second three-way valve TV2 is directly connected to the second port 12, and the configuration is different from that of the first embodiment. . That is, the second switching port 21b of the first three-way valve TV1 is directly connected to the first port 11, and the second switching port 24b of the second three-way valve TV2 is directly connected to the second port 12. FIG. 5 shows the configuration of the fuel cell 1 and the relationship between the first and second ports 11 and 12 and the three-way valves TV1 and TV2.

  As shown in FIG. 4, in order to reverse the flow of the oxidant gas, the controller 30 performs the second and third shut valves SV2 and SV3 and the first and second three-way valves TV1 based on a predetermined control program. , TV2 are controlled respectively. The controller 30 closes the second and third shut valves SV2 and SV3 in order to flow the oxidant gas in the positive direction indicated by the thick arrow in FIG. 4, and the first switching port 21a and the second switching port 21a of the first three-way valve TV1. It opens between the switching port 21b and opens between the second switching port 24b and the third switching port 24c of the second three-way valve TV2. On the other hand, the controller 30 opens the second and third shut valves SV2 and SV3 and reverses the second switching port of the first three-way valve TV1 in order to reverse the oxidant gas flow in the reverse direction indicated by the broken line arrow in FIG. 21b and the third switching port 21c are opened, and the first switching port 24a and the second switching port 24b of the second three-way valve TV2 are opened.

  According to the fuel cell system of this embodiment described above, when the oxidant gas flows in the positive direction, the gas is introduced from the first port 11 into the fuel cell 1 to generate power. The oxidant gas after being used for power generation is led out from the fuel cell 1 through the second port 12. Here, the flow of the oxidant gas supplied to the fuel cell 1 is reversed by the shut valves SV2 and SV3, the three-way valves TV1 and TV2, and the branch passages 16 and 19, so that the gas flows into the second port 12. Is introduced into the fuel cell 1 to generate electricity. The oxidant gas after being used for power generation is led out from the fuel cell 1 through the first port 11. Here, since the first three-way valve TV1 is directly connected to the first port 11 and the second three-way valve TV2 is directly connected to the second port 12, when the flow of the oxidant gas is reversed, Oxidant gas that is not used for power generation is not discharged between the 1 port 11 and the first three-way valve TV1 and between the second port 12 and the second three-way valve TV2. FIG. 6 shows the case where the three-way valves TV1 and TV2 are connected to the first port 11 and the second port 12 via the branch flow paths 16 and 19, respectively. That is, in the fuel cell system shown in FIG. 6, when the flow of the oxidant gas is reversed, the branch flow path 16 between the first port 11 and the first three-way valve TV1, the second port 12 and the second three-way valve. An oxidant gas that is not used for power generation is discharged to the branch channel 19 between the TV 2 and the TV 2. On the other hand, in the fuel cell system shown in FIG. 4, the oxidant gas is not discharged. For this reason, when the flow of the oxidant gas supplied to the fuel cell 1 is reversed, the discharge of the oxidant gas not used for power generation can be prevented, thereby improving the utilization efficiency of the oxidant gas. it can.

  In this embodiment, since the controller 30 controls the shut valves SV2 and SV3 and the three-way valves TV1 and TV2, the supply of the oxidant gas to the fuel cell 1 and the reversal of the oxidant gas flow are automatically performed. For this reason, generation of flooding in the fuel cell 1 and improvement in utilization efficiency of the oxidizing gas can be achieved unattended.

[Third Embodiment]
Next, a third embodiment in which the fuel cell system of the present invention is embodied will be described in detail with reference to the drawings.

  As shown in FIG. 7, in this embodiment, the first three-way valve TV1 is provided directly connected to the first port 11, and the second three-way valve TV2 is provided directly connected to the second port 12. Form and configuration are different. That is, the second switching port 21b of the first three-way valve TV1 is directly connected to the first port 11, and the second switching port 24b of the second three-way valve TV2 is directly connected to the second port 12.

  Therefore, in this embodiment, in addition to the effects of the first embodiment, the first and second three-way valves TV1 and TV2 are provided directly connected to the first port 11 and the second port 12, respectively. When reversed, oxidant gas that is not used for power generation is not discharged between the first port 11 and the first three-way valve TV1 and between the second port 12 and the second three-way valve TV2. For this reason, when the flow of the oxidant gas supplied to the fuel cell 1 is reversed, discharge of the oxidant gas that is not used for power generation can be prevented, thereby improving the utilization efficiency of the oxidant gas. .

  The present invention is not limited to the above-described embodiments, and can be carried out as follows without departing from the spirit of the invention.

  (1) In each of the above embodiments, the reversal of the flow of the oxidant gas has been described. However, the same configuration as that of each of the above embodiments can be employed for the reversal of the flow of the fuel gas.

  (2) In each of the above embodiments, the first three-way valve TV1 is provided to control the introduction and derivation of the gas to the first port 11, and the second three-way is used to control the introduction and derivation of the gas to the second port 12. A valve TV2 was provided. In contrast, an on-off valve for controlling gas introduction to the first port, an on-off valve for controlling gas derivation to the first port, and an on-off valve for controlling gas introduction to the second port, An on-off valve for controlling gas derivation for the two ports may be provided.

1 is a schematic configuration diagram illustrating a fuel cell system according to a first embodiment. Schematic which shows the structure which concerns on a fuel cell and piping. Schematic which shows the structure etc. of a fuel cell. The schematic diagram which concerns on 2nd Embodiment and shows the structure which concerns on a fuel cell and piping. Schematic which shows the structure etc. of a fuel cell. Schematic which shows the contrast with FIG. Schematic which shows the structure which concerns on 3rd Embodiment and concerns on a fuel cell and piping.

Explanation of symbols

1 Fuel Cell 3 First Pipe (First Gas Supply Channel)
4 Second piping 8 In-battery gas passage 11 First port 12 Second port 13 Third port 16 First branch passage (first gas supply passage, first gas discharge passage)
17 Downstream channel (third gas discharge channel)
19 Second branch channel (second gas supply channel, second gas discharge channel)
20 exhaust gas port 31 fuel gas source 32 oxidant gas source TV1 first three-way valve (first on-off valve, second on-off valve)
TV2 2nd 3 way valve (3rd open / close valve, 4th open / close valve)
SV5 5th shut-off valve (5th on-off valve)

Claims (3)

A first port provided in the fuel cell;
A second port provided in the fuel cell;
A gas passage connecting the first port and the second port in the fuel cell;
A third port provided in the fuel cell and connected to the gas passage;
A first gas supply channel connecting the gas source and the first port;
A first on-off valve for opening and closing the first gas supply channel;
A first gas discharge passage connecting the first port and an exhaust gas port;
A second on-off valve for opening and closing the first gas discharge channel;
A second gas supply flow path connecting the gas source and the second port;
A third on-off valve for opening and closing the second gas supply channel;
A second gas exhaust passage connecting the second port and the exhaust gas port;
A fourth on-off valve for opening and closing the second gas discharge channel;
A third gas exhaust passage connecting the third port and the exhaust gas port;
A fuel cell system comprising a fifth on-off valve for opening and closing the third gas discharge channel. A first three-way valve that doubles as the first on-off valve and the second on-off valve connected to the first port, the first gas supply passage, and the first gas discharge passage;
The third on-off valve connected to the second port, the second gas supply passage, and the second gas discharge passage, and a second three-way valve that also serves as the fourth on-off valve. The fuel cell system according to claim 1. A first gas flow state in which gas is introduced into the fuel cell from the first port and led out only from the second port;
A second gas flow state in which the gas is introduced into the fuel cell from the second port and led out only from the first port;
A third gas flow state in which gas is introduced into the fuel cell from the first port and led out from the second port and the third port;
A fourth gas flow state in which gas is introduced into the fuel cell from the first port and the second port and led out from the third port;
A fifth gas flow state in which gas is introduced into the fuel cell from the second port and is led out from the first port and the third port; from the first gas flow state to the third gas flow state; 3. The fuel cell system according to claim 1, wherein the fuel cell system is switched to the second gas flow state through the four gas flow state and the fifth gas flow state.

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