Fuel battery system

Abstract

To provide a technique capable of completing a hydrogen dilution purge and a warm-up operation at a high speed without deteriorating a cell when starting a fuel battery system under a low temperature.SOLUTION: A fuel system comprises: a fuel battery stack; an oxidant gas agent system that circulates an oxidant gas to a plurality of fuel battery cells of a fuel battery stack; a fuel system that circulates the fuel gas to the plurality of fuel battery cells of the fuel battery stack; a cooling system that circulates a cooling gas to between the plurality of fuel battery cells of the fuel battery stack; and a control device that controls the oxidant agent system, the fuel system, and the cooling system. The control device executes: a first lower temperature starting processing that purges a fuel gas flow channel by supplying the fuel gas and the cooling gas to the fuel battery stack at a time of starting at a low temperature of the fuel battery stack; and a second low-temperature starting processing that supplies the fuel gas and the oxidant agent gas also in a state where the supply of the cooling gas is stopped after the first lower temperature starting processing to the fuel battery stack, and increase the temperature while generating the power.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This specification discloses a fuel cell system.

Background Art

[0002] A fuel cell system includes a stack in which fuel cells are stacked, a fuel system that circulates fuel gas through the stack, an oxidant system that circulates oxidant gas through the stack, and a cooling system that circulates refrigerant through the stack. In the gas flow path of the fuel gas, substances that do not contribute to power generation, such as nitrogen, may accumulate during operation stop. Such substances may cause a decrease in power generation efficiency and the like. Patent Document 1 describes performing a fuel gas purge in which fuel gas and the like are circulated with a purge valve provided in the fuel gas flow path open to discharge the substances.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When hydrogen is introduced into the fuel system to perform a hydrogen purge, the exhaust hydrogen needs to be diluted to a certain concentration or less when discharged to the atmosphere. For example, when the oxidant gas or refrigerant is air, hydrogen is diluted with cooling air and discharged to the outside.

[0005] However, when dilution is performed with cooling air during low-temperature startup, the fuel cells are cooled by the circulation of the cooling air, and there is a risk that moisture freezes and blocks inside the fuel cells, resulting in a decrease in power generation performance. On the other hand, when dilution is performed by introducing the oxidant gas into the cells, abnormal potentials are generated inside the cells, deteriorating the cells. Furthermore, water is generated by the reaction of hydrogen and oxygen. In any case, deterioration and performance degradation cannot be avoided during low-temperature startup.

[0006] This specification provides a technique capable of quickly completing a hydrogen dilution purge and a warm-up operation without degrading cells when starting a fuel cell system at low temperature.

Means for Solving the Problems

[0007] The fuel cell system disclosed in this specification includes a fuel cell stack in which a plurality of fuel cells are stacked, an oxidant system that circulates an oxidant gas through the fuel cells of the fuel cell stack, a fuel system that circulates a fuel gas through the fuel cells of the fuel cell stack, a cooling system that circulates a cooling gas between the fuel cells of the fuel cell stack, and a control device that controls the oxidant system, the fuel system, and the cooling system. In this fuel cell system, when starting the fuel cell stack at low temperature, the control device performs a first low-temperature start-up process of supplying the fuel gas and the cooling gas to the fuel cell stack to purge a fuel gas flow path through which the fuel gas flows, and after the first low-temperature start-up process, a second low-temperature start-up process of supplying the fuel gas and the oxidant gas to the fuel cell stack to generate power and raise the temperature while stopping the supply of the cooling gas.

[0008] By doing so, since the purge with the fuel gas (hereinafter, also simply referred to as hydrogen purge) is performed by diluting with the cooling gas, it can be performed while avoiding degradation without generating abnormal potentials. Further, thereafter, by supplying the oxidant gas and the fuel gas to the fuel cell stack to generate power in a state where the supply of the cooling gas is stopped, the hydrogen exhaust can be diluted with the oxidant gas. In addition, by generating power in a state where the cooling gas is not supplied, the stack can be quickly heated up and quickly warmed up.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] One aspect of the fuel cell system disclosed in this specification includes a fuel cell stack in which a plurality of fuel cells are stacked, an oxidant system for flowing an oxidant gas through the fuel cells of the fuel cell stack, a fuel system for flowing a fuel gas through the fuel cells of the fuel cell stack, a cooling system for supplying a cooling gas between the fuel cells of the fuel cell stack, and a control device for controlling the oxidant system, the fuel system, and the cooling system. The control device executes a first low-temperature start-up process of supplying the fuel gas and the cooling gas to the fuel cell stack to purge a fuel gas flow path through which the fuel gas flows when starting up at a low temperature of the fuel cell stack, and a second low-temperature start-up process of supplying the fuel gas and the oxidant gas to the fuel cell stack to generate power and raise the temperature while stopping the supply of the cooling gas after the first low-temperature start-up process.

[0011] Another aspect of the fuel cell system further includes a temperature sensor for detecting the temperature of one or more fuel cells among the plurality of fuel cells, and the control device determines any one of the start and end of the first low-temperature start-up process and the start and end of the second low-temperature start-up process based on the cell temperature detected by the cell temperature sensor. By doing so, the first low-temperature start-up process and / or the second low-temperature start-up process can be accurately started and ended.

[0012] Another aspect of the fuel cell system further includes an external temperature sensor for detecting the external temperature of the fuel cell stack, and may include determining any one of the start and end of the first low-temperature start-up process and the start and end of the second low-temperature start-up process. By doing so, the first low-temperature start-up process and the second low-temperature start-up process can be accurately started and ended.

[0013] Another aspect of the fuel cell system further includes that the oxidant system is provided with a sealing valve capable of sealing the inlet and outlet of the stack, the fuel system is provided with a purge valve for discharging exhaust gas and drain liquid derived from the fuel gas discharged from the fuel cell stack, the fuel cell system is provided with one or more heating devices for heating either or both of the sealing valve and the purge valve, and the control device heats either or both of the sealing valve and the purge valve by the one or more heating devices when executing the first low-temperature start-up process, and may include continuing the heating by the one or more heating devices when executing the second low-temperature start-up process. By doing so, the sealing valve and / or the purge valve can be surely operated, the exhaust gas and / or the drain liquid from the fuel cell stack can be surely discharged, and power generation can be continued.

[0014] Another aspect of the fuel cell system further includes that the fuel cell system is provided with a heating device for the oxidant gas, and the control device may include executing the second low-temperature start-up process using the oxidant gas heated to 0 °C or higher. By doing so, when the oxidant gas at less than 0 °C is supplied, the oxidant gas flow path through which the oxidant gas flows may be blocked. By heating and supplying the oxidant gas to 0 °C or higher, such a risk can be suppressed or avoided. Note that the heating device may be a means for increasing the pressure of the oxidant gas by adiabatic compression. Also by this, the temperature of the oxidant gas can be increased.

[0015] Hereinafter, the fuel cell system (hereinafter, also simply referred to as the system) 2 disclosed in the present specification will be described in detail with appropriate reference to the drawings. FIG. 1 schematically shows the outline of the system, FIG. 2 shows the configuration of the cells constituting the fuel cell stack, and FIG. 3 shows a flowchart of the process executed by the control device included in the system.

[0016] System 2 can be, for example, a system applied as a drive power source for a moving body such as a vehicle, although it is not particularly limited. Also, the type of fuel cell in System 2 is not particularly limited, but for example, it may be meaningful to apply it to a polymer electrolyte fuel cell (PEFC) from the viewpoint of its operating temperature.

[0017] (Fuel cell stack) As shown in FIG. 1, System 2 includes a fuel cell stack (hereinafter, also simply referred to as a stack) 10, a reaction air system 20 for flowing reaction air as an oxidant gas, a hydrogen system 30 for flowing hydrogen as a fuel gas, a cooling air system 40 for flowing cooling air as a cooling gas, and a control device 50. The stack 10 includes a plurality of manifolds (not shown) that independently supply and discharge hydrogen and reaction air to and from the stack 10. The reaction air system is an example of an oxidant system in this specification, the hydrogen system is an example of a fuel system in this specification, and the cooling air system is an example of a cooling system disclosed in this specification.

[0018] As shown in FIG. 2, the stack 10 is configured by stacking a plurality of fuel cells (hereinafter, also simply referred to as cells) 11. The cell 11 is not particularly limited and can adopt a known configuration. For example, the cell 11 includes a membrane electrode assembly (MEA) 12 in which an electrolyte membrane, an air electrode, and a fuel electrode are integrated. The MEA 12 includes an air diffusion layer 12a together with a catalyst layer functioning as an air electrode, and a hydrogen diffusion layer 12b together with a catalyst layer functioning as a fuel electrode. The MEA 12 is held by a frame 13 made of, for example, resin or the like, and separators 16a and 16b are joined to form one cell 11.

[0019] For example, as shown in FIG. 2, reaction air from the reaction air system 20 is supplied and discharged along the positive X-axis direction between the separator 16a and the air diffusion layer 12a of the MEA 12. Also, hydrogen from the hydrogen system 30 is supplied and discharged along the negative X-axis direction between the separator 16b and the hydrogen diffusion layer 12b. The separators 16a and 16b can adopt various known forms.

[0020] Further, the cell 11 includes fins 17 that form cooling air flow paths interposed between the cells 11. The cooling air flow paths are configured in various known forms in addition to such a form. The cooling air is air such as outside air, for example, without being particularly limited.

[0021] (Reaction air system) As shown in FIG. 1, the reaction air system 20 includes a reaction air supply device 22 that takes in air, a reaction air flow path 24, an inlet shut-off valve 26, an outlet shut-off valve 27, and a heater 28.

[0022] The reaction air supply device 22 is, for example, a blower such as an air blower that can be compressed and has a compression ratio of 1.1 or more, without being particularly limited. When air below the freezing point is pressurized to a certain extent, it can be brought to 0°C or higher due to the adiabatic compression effect. For example, when air is compressed 1.1 times, the temperature can be raised by about 10°C. The reaction air supply device 22 capable of compressing and heating air is an example of an oxidant gas supply device including a heating device for the oxidant gas disclosed in this specification.

[0023] The reaction air flow path 24 includes flow paths 24a and 24b. The flow path 24a extends from the reaction air supply device 22 toward the stack 10 and is connected to a reaction air supply manifold (not shown) provided in the stack 10. The flow path 24a is provided with an inlet shut-off valve 26 for sealing the reaction air system 20 of the stack 10 on the flow path.

[0024] The flow path 24b is connected to a reaction air discharge manifold (not shown) of the stack 10. The flow path 24b is provided with an outlet shut-off valve 27 on the flow path. A heater 28 for warming the outlet shut-off valve 27 is provided near the outlet shut-off valve 27 or in its vicinity.

[0025] When the inlet shut-off valve 26 and the outlet shut-off valve 27 are open, the flow paths 24a and 24b supply air into the cells 11 of the stack 10 via the reaction air supply manifold and discharge the air from the stack 10 outside the system 2 via the reaction air discharge manifold.

[0026] Regarding the reaction air supply device 22, the reaction air flow path 24, the inlet shut-off valve 26, the outlet shut-off valve 27, and the heater 28, in particular, they are not particularly limited, and known elements used in fuel cells such as PEFCs can be appropriately used. In addition, the reaction air system 20 can appropriately include various known elements in the reaction air system of the fuel cell.

[0027] (Hydrogen system) As shown in FIG. 1, the hydrogen system 30 includes a hydrogen supply source 32, a hydrogen flow path 34, a pump 35, a gas-liquid separator 36, a purge valve 37, and a heater 38.

[0028] The hydrogen supply source 32 is not particularly limited and may be a hydrogen tank or a hydrogen production device, etc. The flow rate of hydrogen from the hydrogen supply source 32 is regulated by a hydrogen supply valve 33 provided in a flow path 34a leading to the stack 10, a pump 35, etc.

[0029] The hydrogen flow path 34 includes flow paths 34a, 34b, and 34c. The flow path 34a extends from the hydrogen supply source 32 toward the stack 10 and is connected to a hydrogen supply manifold (not shown) of the stack 10. The flow path 34b is connected to a hydrogen discharge manifold (not shown) of the stack 10 and the gas-liquid separator 36. The flow path 34a supplies hydrogen into the cells of the stack 10 via the hydrogen supply manifold, and the flow path 34b discharges hydrogen from the stack 10 via the hydrogen discharge manifold and supplies it to the gas-liquid separator 36.

[0030] The flow path 34c is connected to the gas-liquid separator 36, the pump 35, and the flow path 34a. The flow path 34c supplies the exhaust gas that has passed through the gas-liquid separator 36 to the flow path 34a by the pump 35 and recirculates it to the stack 10.

[0031] The groove flow path formed in the separator 16b of each cell 11 of the stack 10 is an example of the flow path of the fuel gas disclosed in this specification. This flow path may further include a catalyst layer adjacent to the hydrogen diffusion layer 12b, flow paths 24a, 24b, etc., as well as a hydrogen supply manifold and a hydrogen discharge manifold.

[0032] The gas-liquid separator 36 is configured to be able to recycle the gas from which the moisture in the exhaust gas discharged from the stack 10 has been separated back to the stack 10. The pump 35 refluxes the exhaust gas passing through the gas-liquid separator 36 to the flow path 34a at a predetermined pressure for recirculation. The purge valve 37 includes a valve body that is opened and closed to discharge the drained water and drained liquid from the gas-liquid separator 36 to the outside of the system 2. A heater 38 for warming the purge valve 37 is provided near the purge valve 37 or in its vicinity.

[0033] The pump 35, the gas-liquid separator 36, the purge valve 37, and the heater 38 are not particularly limited, and known elements used in fuel cells such as PEFCs can be appropriately used. The hydrogen system 30 can also be appropriately provided with various known elements in the hydrogen system of the fuel cell.

[0034] (Cooling air system) The cooling air system 40 includes a cooling air supply device 42. The cooling air supply device 42 can appropriately use known elements used in fuel cells such as PEFCs, such as a blower that sucks in outside air. As shown in FIG. 2, the cooling air supply device 42 is provided on the side surface of the stack 10 in the positive Z-axis direction, and the cooling gas is configured to flow through the cooling air flow path formed by the fins 17 along the negative Z-axis direction.

[0035] (Control device) The control device 50 is a device that controls the power generation by the fuel cell system 2, and is configured as a computer equipped with a memory. The control device 50 is communicably configured with a reaction air supply device 22, an inlet shutoff valve 26, an outlet shutoff valve 27, and a heater 28 in the reaction air system 20, a hydrogen supply valve 33, a pump 35, a purge valve 37, and a heater 38 in the hydrogen system 30, and a cooling air supply device 42 in the cooling air system 40. Further, it is communicably configured with a cell temperature sensor 60 that detects the temperature of the cell 12 and an external temperature sensor 70 that detects an external temperature such as the outside air temperature outside the system 2, which are provided in the system 2.

[0036] For example, the cell temperature sensor 60 is directly provided on the separator 16a, 16b, or the fin 17 in order to more accurately measure the temperature sensor of the cell 11. Also for example, the external temperature sensor 70 is provided near the cooling air intake so as to be separated from the stack 10 and the heaters 28, 38 to such an extent that it is not affected by their temperatures in order to more accurately measure the outside air temperature of the system 2.

[0037] Next, the low-temperature start-up process performed by the control device 50 at the time of low-temperature start-up of the system 2 will be described with reference to FIG. 3. FIG. 3 shows each step in the reaction air system 20, the hydrogen system 30, and the cooling air system 40. Here, the low-temperature start-up time refers to the time when the operation of the system 2 is started when it is determined to be "low temperature" based on the cell temperature and / or the external temperature measured by the cell temperature sensor 60 and / or the external temperature sensor 70. For example, the low-temperature start-up time is when the ignition switch of the vehicle on which the system 2 is mounted is turned on. The conditions for low-temperature determination based on the cell temperature and the external temperature are appropriately set, for example, to 0°C or lower where there is a risk of freezing and blockage, or 10°C or lower where performance degradation due to low temperature occurs.

[0038] In the start-up standby state of the system 2, the hydrogen supply valve 33 is "closed", the cooling air supply device 42 is "off", the inlet shutoff valve 26 and the outlet shutoff valve 27 are "closed", and the reaction air supply device 22 is "off".

[0039] As shown in FIG. 3, when the control device 50 detects the start of the system 2, the control device 50 first executes a startup preparation process S1. In the startup preparation process S1, the control device 50 activates the heater 28 to thaw the outlet sealing valve 27 (S10). Further, the heater 38 is activated to thaw the purge valve 37 (S20). Each thawing step S10, S20 is a process of heating, for example, to 0 °C or higher so that these valves can be opened and closed and the inside of the valves can be made flowable. The thawing is performed under heating conditions (heating temperature, time, etc.) preset based on the external temperature, the cell temperature, and the capabilities of the heaters 28, 38. Note that the heaters 28, 38 continue to operate as they are. The heaters 28, 38 are examples of one or more heating devices disclosed in this specification.

[0040] Next, the control device 50 executes a first low-temperature startup process S2. The first low-temperature startup process is a process of introducing cooling air and hydrogen from the outside of the system 2 into the stack 10 to perform hydrogen dilution purge and hydrogen replacement. The first low-temperature startup process S2 is executed after the thawing S20 of the purge valve 37 is completed and the purge valve 37 is thawed. By executing the first low-temperature startup process S2, it is possible to perform hydrogen purge by cooling air dilution without introducing air into the cell 11, so that hydrogen replacement can be performed while suppressing freezing blockage and abnormal potential generation in the cell 11.

[0041] In the first low-temperature startup process S2, the control device 50 starts the operation of the cooling air supply device 42 to start the supply of cooling air (S30). Further, the control device 50 opens the purge valve 37, starts the operation of the hydrogen supply source 32, and starts the supply of hydrogen to the stack 10 (S22). Hydrogen is discharged outside the system 2 through the hydrogen diffusion layer 12b of the cell 11 of the stack 10, the gas-liquid separator 36, and the purge valve 37. As a result, nitrogen and the like accumulated in the hydrogen system 30 are removed together with hydrogen and hydrogen replacement is performed. Hydrogen is diluted by the cooling air and discharged outside the system 2.

[0042] The first low-temperature start-up process S2 is executed for a preset required time. This required time may be set as the time estimated for the hydrogen concentration in the hydrogen system 30 to become sufficiently high based on the volume of the hydrogen system and the hydrogen supply rate.

[0043] Next, the control device 50 executes the second low-temperature start-up process S3. In the second low-temperature start-up process S3, reaction air and hydrogen are supplied to the stack 10 to generate power without supplying cooling gas. The exhaust hydrogen generated during power generation can be diluted by the reaction air and exhausted. The stack 10 can be quickly warmed up to the required temperature by power generation.

[0044] In the second low-temperature start-up process S3, the control device 50 first closes the purge valve 37 to stop the discharge of hydrogen (S26), for example. Even in this case, the supply and circulation of hydrogen are continued by the pump. Then, the control device 50 stops the operation of the cooling air supply device 42 (S32). Further, the control device 50 opens the inlet sealing valve 26 and the outlet sealing valve 27 (S12) and starts the operation of the reaction air supply device 22 (S14). The reaction air supply device 22 pressurizes and heats the air to a pressure ratio of, for example, about 1.1 or more and supplies air at, for example, 0°C or higher. By doing so, freezing and blockage of water or the like in the cell 11 can be prevented, which also contributes to the warm-up of the stack 10.

[0045] When the supply of cooling air stops and the supply of reaction air starts, the control device 50 permits the opening of the purge valve 37 (S28). Through these steps, hydrogen exhaust by reaction air dilution and power generation are carried out with the supply of cooling air stopped. Since the heater 38 is operating, the drainage at the purge valve 37 does not freeze, and hydrogen exhaust and power generation continue stably. Also, the operation of the heaters 28 and 38 contributes to the warm-up of the stack 10. Note that it is not necessary to keep the purge valve 37 open during power generation; an appropriate opening operation is sufficient. For example, it is possible to open the purge valve 37 about once a second for several seconds. It is also possible to continue power generation for, for example, about several tens of seconds with the purge valve 37 closed.

[0046] By performing the steps in the above order, it is possible to avoid the release of hydrogen outside the system 2 without dilution. Note that by stopping the operation of the cooling air supply device 42 (S32) simultaneously with or before the start of the operation of the reaction air supply device 22 (S14), it is possible to reliably prevent the discharge of hydrogen outside the system 2 without dilution.

[0047] When the second low-temperature start-up process S3 is thus started, the control device 50 determines whether the cell temperature acquired from the cell temperature sensor 60 at a predetermined interval has reached the warm-up target temperature (S36). The warm-up target temperature is not particularly limited, but for example, it is 30°C. When the cell temperature reaches the warm-up target temperature, the control device 50 starts the operation of the cooling air supply device 42 (step S36), ends the second low-temperature start-up process S3, and shifts to the normal operation process (step S4).

[0048] When the control device 50 determines that the cell temperature has not reached the warm-up target temperature, it continues to monitor the cell temperature as it is (step S34) and continues the second low-temperature start-up process.

[0049] According to the system 2 capable of executing the above low-temperature start-up process, at low temperatures, hydrogen purging is performed by dilution with a cooling gas and then hydrogen exhaust is performed by dilution with reaction air as an oxidant gas while generating power at the same time. For this reason, since hydrogen purging and hydrogen exhaust can be performed by cooling air and reaction air, it is possible to avoid or suppress the adverse effects of continuously supplying cooling air and generate power. Freezing blockage and the like inside the cell 11 can be suppressed, power generation can be stably performed, and the stack 10 can be warmed up more quickly.

[0050] In the above-described embodiment, the first low-temperature start-up process S2 is started and ended based on the cell temperature detected by the cell temperature sensor 60 and the external temperature detected by the external temperature sensor 70, and then the second low-temperature start-up process S3 is started. The second low-temperature start-up process S3 is ended based on the cell temperature. However, the present invention is not limited to this. It is also possible to execute either the start or the end of the first and second low-temperature start-up processes based on either or both of the cell temperature and the external temperature. Further, if necessary, the start and end of the low-temperature start-up process may be executed based on other conditions inside and outside the system 2.

[0051] In the above-described embodiment, the heaters 28 and 38 are used to heat the outlet sealing valve 27 and the purge valve 37, respectively. However, the present invention is not limited to this, and they may be appropriately operated as necessary. Depending on the degree of "low temperature" during low-temperature start-up, both of these heaters 28 and 38 may not be required.

[0052] In the above-described embodiment, the reaction air supply device 22 is a blower such as a blower capable of adiabatic compression with an adiabatic compression ratio of 1.1 or more. However, the present invention is not limited to this, and it may be provided with a device for heating air.

[0053] As described above, specific examples of the technology disclosed in this specification have been described in detail. However, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples exemplified above, such as, for example, a fuel cell control method. The technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology exemplified in this specification or the drawings can achieve a plurality of purposes simultaneously, and achieving one of these purposes itself has technical utility.

[0054] This specification includes the following aspects. [1] A fuel cell stack in which a plurality of fuel cells are stacked, An oxidant system that circulates oxidant gas through the plurality of fuel cells of the fuel cell stack, and a fuel system that circulates fuel gas through the plurality of fuel cells of the fuel cell stack, a cooling system that circulates cooling gas between the plurality of fuel cells of the fuel cell stack, and a control device that controls the oxidant system, the fuel system, and the cooling system, comprising, when starting the fuel cell stack at a low temperature, the control device performs a first low-temperature start-up process of supplying the fuel gas and the cooling gas to the fuel cell stack to purge a fuel gas flow path through which the fuel gas flows, and after the first low-temperature start-up process, in a state where the supply of the cooling gas is stopped, supplies the fuel gas and the oxidant gas to the fuel cell stack to generate power and raise the temperature, a fuel cell system that executes a second low-temperature start-up process. [2] Further, a cell temperature sensor that detects the temperature of one or more of the plurality of fuel cells is provided, Based on the cell temperature detected by the cell temperature sensor, the control device determines any one of the start and end of the first low-temperature start-up process and the start and end of the second low-temperature start-up process, the fuel cell system according to [1]. [3] Further, an external temperature sensor that detects the external temperature of the fuel cell stack is provided, Based on the external temperature detected by the external temperature sensor, the control device determines any one of the start and end of the first low-temperature start-up process and the start and end of the second low-temperature start-up process, the fuel cell system according to [1] or [2]. [4] Further, the oxidant system includes a sealing valve that can seal the stack inlet and outlet, the fuel system includes a purge valve for discharging exhaust gas and drainage liquid derived from the fuel gas discharged from the fuel cell stack, the fuel cell system includes one or a plurality of heating devices that heat either or both of the sealing valve and the purge valve, When the control device executes the first low-temperature start-up process, it heats either or both of the sealing valve and the purge valve by the one or more heating devices, and when executing the second low-temperature start-up process, continues heating by the one or more heating devices. The fuel cell system according to any one of [1] to [3]. [5] Further, it includes a heating device for the oxidant gas, When the control device executes the second low-temperature start-up process, it uses the oxidant gas heated to 0°C or higher. The fuel cell system according to any one of [1] to [4].

Explanation of reference numerals

[0055] 2 Fuel cell system, 10 Fuel cell stack, 11 Fuel cell, 12 MEA, 13 Frame, 16a, 16b Separator, 17 Fin, 20 Reaction air system, 22 Reaction air supply device, 24, 24a, 24b Reaction air flow path, 26 Inlet sealing valve, 27 Outlet sealing valve, 28 Heater, 30 Hydrogen system. 32 Hydrogen supply source, 33 Hydrogen supply valve, 34, 34a, 34b, 34c Flow path, 35 Pump, 36 Gas-liquid separator, 37 Purge valve, 38 Heater, 40 Cooling air system, 42 Cooling air supply device, 50 Control device, 60 Cell temperature sensor, 70 External temperature sensor

Claims

1. A fuel cell stack in which a plurality of fuel cells are stacked, an oxidant system that circulates an oxidant gas through the plurality of fuel cells of the fuel cell stack, a fuel system that circulates a fuel gas through the plurality of fuel cells of the fuel cell stack, a cooling system that circulates a cooling gas between the plurality of fuel cells of the fuel cell stack, a control device that controls the oxidant system, the fuel system, and the cooling system, comprising: when starting up at low temperature of the fuel cell stack, the control device performs a first low-temperature start-up process of supplying the fuel gas and the cooling gas to the fuel cell stack to purge a fuel gas flow path through which the fuel gas flows, and after the first low-temperature start-up process, a second low-temperature start-up process of supplying the fuel gas and the oxidant gas to the fuel cell stack to generate power and raise the temperature while stopping the supply of the cooling gas. A fuel cell system.

2. Furthermore, it includes a cell temperature sensor that detects the temperature of one or more fuel cells among the plurality of fuel cells, Based on the cell temperature detected by the cell temperature sensor, the control device determines any one of the start and end of the first low-temperature start-up process and the start and end of the second low-temperature start-up process. The fuel cell system according to claim 1.

3. Furthermore, it includes an external temperature sensor that detects the external temperature of the fuel cell stack, Based on the external temperature detected by the external temperature sensor, the control device determines any one of the start and end of the first low-temperature start-up process and the start and end of the second low-temperature start-up process. The fuel cell system according to claim 1.

4. Furthermore, the oxidant system includes a sealing valve that can seal the stack inlet and outlet, the fuel system includes a purge valve for discharging exhaust gas and drainage derived from the fuel gas discharged from the fuel cell stack, the fuel cell system includes one or more heating devices that heat either or both of the sealing valve and the purge valve, When executing the first low-temperature start-up process, the control device heats either or both of the sealing valve and the purge valve by the one or more heating devices, and when executing the second low-temperature start-up process, continues heating by the one or more heating devices. The fuel cell system according to claim 1.

5. Furthermore, it includes a heating device for the oxidant gas The fuel cell system according to claim 1, wherein the control device executes the second low-temperature start-up process using the oxidant gas heated to 0°C or higher.

Images