JP2010177210A - Fuel cell system and starting method therefor - Google Patents

Abstract

An object of the present invention is to reduce energy consumption at the time of dilution satisfactorily and to start up economically.
A controller 21 constituting a fuel cell system 10 stops operation of an anode gas replacement device 82 that performs replacement of hydrogen in an anode gas flow path 36 via an anode gas supply device 16 and a fuel cell stack 12. The cathode gas flow rate supplied from the cathode gas supply device 14 is changed according to the soak time at the time of replacement of the hydrogen by the soak time detection device 84 for detecting the soak time and the anode gas replacement device 82. A cathode gas flow rate control device 86.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell system including a fuel cell, a cathode gas supply device, an anode gas supply device, an anode gas replacement device, and a dilution device, and a startup method thereof.

  A fuel cell supplies an anode gas (mainly hydrogen-containing gas) and a cathode gas (mainly oxygen-containing gas) to the anode-side electrode and the cathode-side electrode, and causes them to react electrochemically. A system for obtaining 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 mounted on a vehicle such as an automobile, for example, by alternately stacking a predetermined number of electrolyte membrane / electrode structures and separators.

  In this type of fuel cell, when power generation (operation) is stopped, the supply of anode gas and cathode gas to the fuel cell is stopped. However, while the anode gas remains on the anode side electrode, the cathode side electrode The cathode gas remains. For this reason, while the fuel cell is stopped, the cathode gas (air) that has permeated the electrolyte membrane from the cathode side moves to the anode side, and the cathode gas exists in the cathode side electrode and the anode side electrode.

  Therefore, in order to provide a method for starting a fuel cell device that can be restarted quickly even after long-term power generation is stopped, for example, a method for starting a fuel cell device disclosed in Patent Document 1 is known. . This Patent Document 1 includes a fuel cell main body, a hydrogen storage cylinder that stores hydrogen necessary for the fuel cell main body, a pressure control unit that controls the pressure of hydrogen supplied from the hydrogen storage cylinder to the fuel cell main body, A hydrogen control valve for controlling the flow of hydrogen, an air supply means for supplying oxygen necessary for power generation of the fuel cell to the fuel cell body, a control unit for controlling the air supply means, and an anode of the fuel cell Hydrogen sealing comprising a discharge valve provided on the pole side, a switch for controlling an external output from the fuel cell main body, and a control unit for monitoring the output voltage of the fuel cell and controlling the discharge valve and the switch It is related with the starting method of a fuel cell device of a type.

  When starting the fuel cell main body, the hydrogen control valve that controls the flow of hydrogen from the hydrogen storage cylinder is opened, and then the air is supplied from the air supply means by the signal from the control unit that controls the air supply means. Supply to the main body, then open the discharge valve, and after the fuel cell output voltage exceeds a certain voltage, close the discharge valve with a signal from the control unit controlling the discharge valve, and start external output Yes.

Japanese Patent Application Laid-Open No. 11-097047

  By the way, in the above prior art, after opening the hydrogen control valve and increasing the pressure on the anode electrode side, air is supplied to the fuel cell, and then the exhaust valve is opened to inactivate the staying reaction. The gas is exhausted. At that time, hydrogen, which is an anode gas, cannot be discharged directly, but must be diluted with air, which is a cathode gas.

  In this case, the amount of hydrogen discharged from the fuel cell via the discharge valve varies depending on the fluctuation of the soak time. This is because the anode gas is consumed due to a chemical reaction at the time of stopping, and the residual hydrogen amount is reduced due to out leak or cross leak.

  However, in the above-described conventional technology, the amount of air for diluting the hydrogen discharged from the fuel cell is set to the maximum amount required for dilution regardless of the fluctuation of the residual hydrogen amount. Thereby, when diluting hydrogen, an air amount more than necessary is sent, and there is a problem that energy consumption for driving the compressor (pump) increases, which is not suitable for energy saving.

  An object of the present invention is to solve this type of problem, and to provide a fuel cell system capable of starting up economically while reducing energy consumption at the time of dilution, and a starting method thereof. To do.

  The present invention relates to a fuel cell that generates electricity by an electrochemical reaction between a cathode gas supplied to a cathode gas flow channel and an anode gas supplied to an anode gas flow channel, a cathode gas supply device that supplies the cathode gas, and the anode gas. Anode gas supply device to be supplied, an anode gas replacement device that replaces the anode gas in the anode gas flow path via the anode gas supply device when the fuel cell is started up, and exhausted from the fuel cell The present invention relates to a fuel cell system including a diluting device that mixes and dilutes an anode off gas with the cathode gas supplied from the cathode gas supplying device.

  This fuel cell system includes a soak time detection device that detects a soak time during which the operation of the fuel cell is stopped, and a cathode gas flow rate supplied from the cathode gas supply device when the anode gas is replaced by the anode gas replacement device. And a cathode gas flow rate control device which is changed according to the soak time.

  The cathode gas flow rate control device preferably includes a control map for increasing the cathode gas flow rate as the soak time becomes shorter.

  Further, the cathode gas flow rate control device can set the cathode gas flow rate at the time of replacing the anode gas to the minimum flow rate value required at the OCV (open circuit voltage) when the anode gas flow path is scavenged with the cathode gas during the soak. preferable.

  Furthermore, it is preferable that the cathode gas flow rate control device sets the cathode gas flow rate at the time of anode gas replacement to the minimum flow rate value required at the OCV when the soak time is longer than the set time.

  Further, the cathode gas flow rate control device preferably includes a control map for decreasing the cathode gas flow rate as the soak time becomes shorter.

  Further, the cathode gas flow rate control device preferably sets the cathode gas flow rate at the time of the anode gas replacement to the maximum flow rate value required at the OCV when scavenging the anode gas flow path with the cathode gas during the soak.

  Furthermore, it is preferable that the cathode gas flow rate control device sets the cathode gas flow rate at the time of anode gas replacement to the highest flow rate value required at OCV when the soak time is longer than the set time.

  Further, the fuel cell system includes means for detecting the remaining amount of anode gas remaining in the fuel cell at the previous stop, and means for correcting the cathode gas flow rate at the time of anode gas replacement based on the remaining amount of anode gas. It is preferable to provide.

  Further, this fuel cell system preferably includes means for detecting the temperature of the fuel cell at the time of startup, and means for correcting the cathode gas flow rate at the time of anode gas replacement based on the temperature of the fuel cell.

  Furthermore, the fuel cell system includes a cooling medium supply device that supplies a cooling medium to the fuel cell, and a water pump that constitutes the cooling medium supply device and an air pump that constitutes the cathode gas supply device are coaxially driven. It is preferable. The air pump is preferably driven at a constant rotation.

  Furthermore, the present invention relates to a fuel cell that generates electric power by an electrochemical reaction of a cathode gas supplied to a cathode gas channel and an anode gas supplied to an anode gas channel, a cathode gas supply device that supplies the cathode gas, and the anode An anode gas supply device that supplies gas, an anode gas replacement device that replaces the anode gas in the anode gas flow path via the anode gas supply device when the fuel cell is started, and an exhaust gas from the fuel cell The present invention relates to a method for starting a fuel cell system including a diluting device that mixes and dilutes the anode off gas to be mixed with the cathode gas supplied from the cathode gas supply device.

  In this activation method, the soak time during which the operation of the fuel cell is stopped is detected, and the cathode gas flow rate supplied from the cathode gas supply device at the time of replacement of the anode gas by the anode gas replacement device is set to the soak time. And changing the process accordingly.

  Furthermore, this starting method preferably increases the cathode gas flow rate as the soak time decreases.

  Further, when the anode gas flow path is scavenged with the cathode gas during the soak, the cathode gas flow rate at the time of anode gas replacement is preferably set to the minimum flow rate value required at the OCV.

  Further, when the soak time is longer than the set time, it is preferable to set the cathode gas flow rate at the time of anode gas replacement to the minimum flow rate value required at the OCV.

  Furthermore, this starting method preferably reduces the cathode gas flow rate as the soak time decreases.

  Further, when the anode gas flow path is scavenged with the cathode gas during the soak, it is preferable to set the cathode gas flow rate at the time of the anode gas replacement to the maximum flow rate value required at the OCV.

  Furthermore, when the soak time is equal to or longer than the set time, it is preferable to set the cathode gas flow rate at the time of anode gas replacement to the maximum flow rate value required at the OCV.

  Furthermore, the start-up method includes a step of detecting the remaining amount of anode gas remaining in the fuel cell at the previous stop, a step of correcting the cathode gas flow rate at the time of anode gas replacement based on the remaining amount of anode gas, and It is preferable to have.

  The starting method preferably includes a step of detecting the temperature of the fuel cell at the time of starting, and a step of correcting the cathode gas flow rate at the time of replacing the anode gas based on the temperature of the fuel cell.

  In the present invention, when the fuel cell is started, the cathode gas flow rate supplied from the cathode gas supply device is changed according to the soak time, so that it can be diluted according to fluctuations in the amount of anode gas remaining in the fuel cell. The cathode gas flow rate is set.

  As a result, the cathode gas flow rate is set so that the anode gas actually remaining inside the fuel cell can be diluted well, so that the cathode gas supply device is not driven more than necessary. Therefore, energy consumption can be appropriately controlled, which is economical.

It is a schematic block diagram of the fuel cell system for enforcing the starting method concerning a 1st embodiment of the present invention. It is a flowchart explaining the said starting method. It is a control map of soak time and air flow rate. It is a schematic block diagram of the fuel cell system for implementing the starting method which concerns on the 2nd Embodiment of this invention. It is a control map of soak time and air flow rate. It is a flowchart explaining the said starting method. It is a flowchart explaining an air flow rate correction process. It is a flowchart explaining the starting method which concerns on the 3rd Embodiment of this invention. It is a control map of soak time and air flow rate. It is a flowchart explaining the starting method which concerns on the 4th Embodiment of this invention. It is a control map of soak time and air flow rate.

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

  The fuel cell system 10 includes a fuel cell stack 12, a cathode gas supply device 14 for supplying a cathode gas such as an oxygen-containing gas (hereinafter simply referred to as air) to the fuel cell stack 12, and a hydrogen content in the fuel cell stack 12. An anode gas supply device 16 for supplying an anode gas such as a gas (hereinafter simply referred to as hydrogen), a cooling medium supply device 18 for supplying a cooling medium to the fuel cell stack 12, and an anode discharged from the fuel cell stack 12 A diluting device 20 that mixes and dilutes off-gas with air supplied from the cathode gas supply device 14 and a controller 21 are provided. In addition, although the cathode offgas discharged | emitted from the fuel cell stack 12 is introduce | transduced into the dilution apparatus 20, in order to dilute anode offgas, you may bypass the said fuel cell stack 12 and introduce | transduce air directly.

  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 an anode side electrode 26 and a cathode side electrode 28, and the electrolyte membrane / electrode structure 30 is paired with a pair of separators 32, 34.

  The separator 32 is formed with an anode gas flow path 36 for supplying hydrogen to the anode side electrode 26, and the separator 34 is formed with a cathode gas flow path 38 for supplying air to the cathode side electrode 28. A cooling medium flow path 40 for temperature adjustment is formed between the separators 32 and 34.

  At one end of the fuel cell stack 12, a cathode gas inlet communication hole 42a for supplying air and an anode gas inlet communication hole 44a for supplying hydrogen are formed. At the other end of the fuel cell stack 12, a cathode gas outlet communication hole 42b for discharging air and an anode gas outlet communication hole 44b for discharging hydrogen are formed.

  The fuel cell stack 12 is further formed with a cooling medium inlet communication hole 46a for supplying a cooling medium such as pure water or ethylene glycol, and a cooling medium outlet communication hole 46b for discharging the cooling medium.

  The cathode gas inlet communication hole 42 a and the cathode gas outlet communication hole 42 b communicate with the cathode gas flow path 38 of each fuel cell 22, and the anode gas inlet communication hole 44 a and the anode gas outlet communication hole 44 b communicate with each fuel cell 22. It communicates with the anode gas flow path 36. The cooling medium inlet communication hole 46 a and the cooling medium outlet communication hole 46 b communicate with the cooling medium flow path 40 of each fuel cell 22.

  The cathode gas supply device 14 includes an air pump 50 that compresses and supplies air from the atmosphere, and the air pump 50 is disposed in the air supply passage 52. The air supply passage 52 communicates with the cathode gas inlet communication hole 42 a of the fuel cell stack 12. The cathode gas supply device 14 includes an air discharge passage 54 that communicates with the cathode gas outlet communication hole 42b. The air discharge passage 54 is connected to the dilution device 20 via a purge valve 56.

  The anode gas supply device 16 includes a hydrogen supply unit 58 having a hydrogen tank that stores high-pressure hydrogen (hydrogen-containing gas). The hydrogen supply unit 58 is connected to the anode gas inlet of the fuel cell stack 12 via the hydrogen supply passage 60. It communicates with the communication hole 44a. The hydrogen supply passage 60 is provided with an open / close valve 62, and a bypass passage 64 is connected to the hydrogen supply passage 60 and the air supply passage 52. An open / close valve 66 is disposed in the bypass passage 64.

  The anode gas supply device 16 includes a hydrogen discharge passage 68 that communicates with the anode gas outlet communication hole 44b. The hydrogen discharge passage 68 is connected to the dilution device 20 via the purge valve 70.

  The cooling medium supply device 18 includes a water pump 72, and the water pump 72 is connected to the cooling medium inlet communication hole 46 a and the cooling medium outlet communication hole 46 b of the fuel cell stack 12 through the cooling medium circulation passage 74. A radiator 76 is disposed in the cooling medium circulation passage 74.

  The air pump 50 constituting the cathode gas supply device 14 and the water pump 72 constituting the cooling medium supply device 18 are coaxially connected to a single motor 78 and driven coaxially. The fuel cell stack 12 is connected to a voltage / current monitor 80 that monitors the voltage and current during power generation. The fuel cell stack 12 is connected to a power storage device, for example, a battery 81, and the battery 81 can supply power to the motor 78 and the like.

  The controller 21 detects the soak time during which the operation of the fuel cell stack 12 is stopped, and the anode gas replacement device 82 that replaces the hydrogen in the anode gas flow path 36 via the anode gas supply device 16. A cathode gas flow rate control device 86 for changing the cathode gas flow rate supplied from the cathode gas supply device 14 according to the soak time when the hydrogen is replaced by the device 84, the anode gas replacement device 82, and a control described later. And a storage device 88 for storing a map or the like.

  The operation of the fuel cell system 10 configured as described above will be described below along the flowchart shown in FIG.

  When starting the fuel cell system 10 whose operation has been stopped (that is, during soaking), first, it is determined whether or not scavenging by air (cathode gas) has been performed on the anode gas flow path 36 during soaking. (Step S1). If it is determined that scavenging by the cathode gas is not performed during the soak (NO in step S1), the process proceeds to step S2, and the soak time detector 84 calculates the soak time via a timer (not shown), for example. Is done.

  Furthermore, it progresses to step S3 and the target air flow rate (cathode gas flow rate) at the time of starting is calculated from the calculated soak time. In the controller 21, a control map of soak time and air flow rate is stored in the storage device 88 in advance.

  In the first embodiment (the same applies to the second embodiment), the gas in the anode gas flow path system (the anode gas inlet communication hole 44a, the anode gas flow path 36, and the anode gas outlet communication hole 44b) during the OCV purge is performed. Are all replaced with anode gas.

  Therefore, in the control map, as shown in FIG. 3, the air flow rate is increased as the soak time is shortened, and when the soak time exceeds a certain time T1 (several hours), the air flow rate is The required minimum flow rate value V1 is set. This is because if the soak time is short, the amount of hydrogen remaining in the anode gas flow path system is large, so that the amount of hydrogen discharged when the gas is replaced by the OCV purge increases, and the air flow rate needs to be increased. Note that the minimum flow rate value V1 is the same as the predetermined value V1 when scavenging is performed during soaking, as will be described later.

  Therefore, the cathode gas flow rate control device 86 controls the air pump 50 constituting the cathode gas supply device 14 and the hydrogen supply unit 58 constituting the anode gas supply device 16 based on the target air flow rate calculated in step S3. Is driven (step S4).

  In the anode gas supply device 16, as shown in FIG. 1, the hydrogen supplied from the hydrogen supply unit 58 passes through the hydrogen supply passage 60 under the opening action of the on-off valve 62, and the anode gas inlet communication hole of the fuel cell stack 12. 44a. The hydrogen supplied to the anode gas inlet communication hole 44a is introduced into the anode gas flow path 36, moves along the electrode surface of the anode side electrode 26 of each fuel cell 22, and then discharged to the anode gas outlet communication hole 44b. The

  Therefore, the remaining gas (including hydrogen) in the anode gas flow path system (the anode gas inlet communication hole 44a, the anode gas flow path 36, and the anode gas outlet communication hole 44b) of the fuel cell stack 12 is replaced with new hydrogen. . This residual gas and new hydrogen (anode off gas) are introduced into the diluting device 20 through the hydrogen discharge passage 68 under the action of opening the purge valve 70.

  On the other hand, in the cathode gas supply device 14, the motor 78 is rotated by the electric power from the battery 81, and the air pump 50 starts to be driven. The compressed air supplied from the air pump 50 is supplied to the cathode gas inlet communication hole 42 a of the fuel cell stack 12 through the air supply passage 52.

  In each fuel cell 22 constituting the fuel cell stack 12, the air supplied to the cathode gas inlet communication hole 42 a is introduced into the cathode gas flow path 38 and moves along the electrode surface of the cathode side electrode 28, and then the cathode It is discharged into the gas outlet communication hole 42b. This air (cathode off-gas) is introduced into the diluting device 20 through the air discharge passage 54 under the opening action of the purge valve 56.

  In this case, as shown in FIG. 3, the first embodiment has a control map in which the relationship between the soak time and the air flow rate is set in advance. The flow rate is set.

  At that time, in the fuel cell stack 12, when the soak time becomes long, hydrogen is consumed by a chemical reaction, and the residual hydrogen amount decreases due to out leak or cross leak. Accordingly, by reducing the air flow rate at the time of startup as the soak time becomes longer, an appropriate air flow rate that can sufficiently dilute the hydrogen actually remaining in the fuel cell stack 12 is set.

  For this reason, the air pump 50 which comprises the cathode gas supply apparatus 14 is not driven more than necessary. Thereby, the electric power supplied to the motor 78 for driving the air pump 50 is reduced, the energy consumption of the battery 81 can be appropriately controlled, and the effect of being economical is obtained.

  In the cooling medium supply device 18, the water pump 72 is driven coaxially with the air pump 50 under the rotating action of the motor 78. The cooling medium supplied to the cooling medium circulation passage 74 via the water pump 72 is introduced into the cooling medium flow path 40 from the cooling medium inlet communication hole 46 a of the fuel cell stack 12. After cooling each fuel cell 22, the cooling medium is discharged from the cooling medium outlet communication hole 46 b to the cooling medium circulation passage 74.

  Next, the process proceeds to step S 5, where the OCV of the fuel cell stack 12 is detected via the voltage / current monitor 80. When the OCV detected by the voltage / current monitor 80 reaches a set value and / or when a predetermined time has elapsed since the start of the fuel cell stack 12, it is determined that the start of the fuel cell stack 12 has been completed. (YES in step S6).

  On the other hand, if it is determined in step S1 that the anode gas flow path 36 has been scavenged with air during the soak (YES in step S1), the process proceeds to step S7, where the target air flow rate at startup is the predetermined value V1, that is, The minimum flow rate value V1 for OCV is set.

  Here, scavenging with air in the anode gas flow path 36 closes the open / close valve 62, opens the open / close valve 66, closes the purge valve 56, and opens the purge valve 70. In this state, when the air pump 50 is driven via the motor 78, external air is supplied from the air supply passage 52 through the bypass passage 64 to the anode gas inlet communication hole 44 a of the fuel cell stack 12. The air supplied from the anode gas inlet communication hole 44 a to the hydrogen supply passage 60 discharges the gas remaining in the anode gas passage system of the fuel cell stack 12 from the hydrogen discharge passage 68 to the dilution device 20.

  As described above, since the anode gas channel system is scavenged with air, the amount of hydrogen remaining in the anode gas channel system is greatly reduced when the anode gas is replaced in step S4. Therefore, it is sufficient to supply at least the air amount of the minimum flow rate value V1 for the OCV check, and there is an advantage that energy consumption is effectively reduced.

  In the first embodiment, the air pump 50 and the water pump 72 are coaxially driven via the motor 78. For this reason, for example, when the soak time is long and the rotation speed of the air pump 50 is decreased, the rotation speed of the water pump 72 is also decreased, the flow rate of the cooling medium is decreased, and the fuel cell stack 12 is warmed up. There is an advantage of being promoted.

  Furthermore, since the rotation speed of the air pump 50 is kept constant, it is possible to effectively reduce, for example, noise due to fluctuations in the rotation speed of the air pump 50 before power generation of the fuel cell stack 12.

  FIG. 4 is a schematic configuration diagram of a fuel cell system 90 for carrying out the starting method according to the second embodiment of the present invention. 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 90 includes a controller 92. The controller 92 detects the remaining amount of hydrogen remaining in the fuel cell stack 12 at the time of the previous stop, and first corrects a control map (air flow rate) based on the remaining amount of hydrogen. An air flow rate correcting unit 96, a fuel cell temperature detecting unit 98 for detecting the temperature of the fuel cell stack 12 at the time of startup, and a second air for correcting a control map (air flow rate) based on the temperature of the fuel cell stack 12 The flow rate correcting means 100 is further provided. Note that the first air flow rate correcting unit 96 and the second air flow rate correcting unit 100 may be configured by a single unit.

  As shown in FIG. 5, the first and second air flow rate correcting means 96 and 100 are configured to increase the air flow rate according to a linear function of a preset air flow rate and soak time (see the inclined line L1), Or it correct | amends in the direction (refer inclination line L2) which reduces an air flow rate.

  The hydrogen remaining amount detecting means 94 detects the remaining amount of hydrogen based on the pressure of residual hydrogen in the fuel cell stack 12 and the like, and the fuel cell temperature detecting means 98 detects the temperature of the fuel cell stack 12 using a temperature sensor or the like. . The temperature of the fuel cell stack 12 can be detected from the temperature of the cooling medium, the temperature of hydrogen, or the temperature of air, or the temperature of the fuel cell stack 12 itself may be directly detected.

  The operation of the second embodiment configured as described above will be described below along the flowchart shown in FIG.

  First, after Steps S11 to S13 are performed in the same manner as Steps S1 to S3 of the first embodiment, the process proceeds to Step S14 and air flow rate correction processing is performed.

  In this air flow rate correction process, as shown in FIG. 7, the remaining amount of hydrogen remaining in the fuel cell stack 12 at the previous stop is detected (step S21), and based on the detected remaining amount of hydrogen, FIG. The air flow rate shown in FIG. 5 is corrected (step S22). That is, as the remaining amount of hydrogen increases, the air flow rate needs to be increased. For example, the air flow rate is corrected on the inclined line L1 side.

  In step S23, the temperature of the fuel cell stack 12 at the time of startup is detected, and the air flow rate is corrected based on the detected temperature (step S24). Here, the higher the temperature of the fuel cell stack 12 at startup, the greater the volume of air when passing through the fuel cell stack 12. For this reason, when the temperature of the fuel cell stack 12 at the time of start-up is high, for example, the air flow rate is corrected to the inclined line L2 side in FIG. 5 so as to reduce the air flow rate derived from the air pump 50. .

  In the air flow rate correction process, the air flow rate may be corrected based on the temperature of the fuel cell stack 12 at the time of stoppage, the temperature change in the soak, or the like in addition to the above process. After the above air flow rate correction process is performed, Steps S15 to S18 are performed in the same manner as Steps S4 to S7 of the first embodiment.

  Thus, in the second embodiment, highly accurate control of the air pump 50 is performed based on the remaining amount of hydrogen, the temperature of the fuel cell stack 12, and the like. Accordingly, it is possible to effectively reduce the energy consumption for diluting hydrogen and to perform a reliable dilution process.

  Next, an activation method according to the third embodiment of the present invention will be described below along the flowchart shown in FIG. In the third embodiment, the fuel cell system 10 is used as in the first embodiment.

  First, after step S21 and step S22 are performed, the process proceeds to step S23, and the startup target OCV purge amount is calculated from the calculated soak time. Then, the startup target air flow rate is calculated from the calculated startup target OCV purge amount (step S24).

  At this time, a control map of the soak time and the startup target OCV purge amount is stored in the controller 21 in advance. In this control map, as shown in FIG. 9, the air flow rate is reduced as the soak time is shortened, and when the soak time exceeds a certain time T2 (several hours), the air flow rate is required at the time of OCV. The maximum flow rate value V2 is set. This is because when the soak time is short, the hydrogen concentration in the anode gas flow path system is relatively high, so that the amount of hydrogen replaced by the OCV purge is small and the air flow rate is small. The maximum flow rate value V2 is the same as the predetermined value V2 when scavenging is performed during soaking.

  Further, Step S25 to Step S28 are performed in the same manner as Step S4 to Step S7 of the first embodiment.

  Accordingly, in the third embodiment, since the air flow rate is controlled according to the amount of hydrogen remaining in the anode gas flow path system, the energy consumption is effectively reduced, and the same as in the first embodiment described above. An effect is obtained.

  Next, an activation method according to the fourth embodiment of the present invention will be described below along the flowchart shown in FIG. In the fourth embodiment, the fuel cell system 90 is used as in the second embodiment.

  First, Steps S31 to S34 are performed in the same manner as Steps S21 to S24 of the third embodiment, and then the process proceeds to Step S35 to perform air flow rate correction processing (see FIG. 11).

  As a result, in the fourth embodiment, energy consumption for hydrogen dilution is effectively reduced, and the same effects as in the second embodiment are obtained, such as a reliable dilution process being performed.

DESCRIPTION OF SYMBOLS 10, 90 ... Fuel cell system 12 ... Fuel cell stack 14 ... Cathode gas supply device 16 ... Anode gas supply device 18 ... Cooling medium supply device 20 ... Dilution device 21, 92 ... Controller 22 ... Fuel cell 24 ... Solid polymer electrolyte membrane 26 ... Anode side electrode 28 ... Cathode side electrode 30 ... Electrolyte membrane / electrode structure 32, 34 ... Separator 36 ... Anode gas flow path 38 ... Cathode gas flow path 40 ... Cooling medium flow path 50 ... Air pump 56, 70 ... Purge valve 58 ... Hydrogen supply section 72 ... Water pump 78 ... Motor 81 ... Battery 82 ... Anode gas replacement device 84 ... Soak time detection device 86 ... Anode gas flow rate control device 88 ... Storage device 94 ... Hydrogen remaining amount detection means 96, 100 ... Air Flow rate correction means 98 ... Fuel cell temperature detection means

Claims (20)

A fuel cell that generates electricity by an electrochemical reaction between a cathode gas supplied to a cathode gas flow channel and an anode gas supplied to an anode gas flow channel, a cathode gas supply device that supplies the cathode gas, and an anode gas that supplies the anode gas A supply device, an anode gas replacement device that replaces the anode gas in the anode gas flow path via the anode gas supply device when the fuel cell is started, and an anode off-gas discharged from the fuel cell. A fuel cell system comprising a diluting device for mixing and diluting with the cathode gas supplied from the cathode gas supplying device,
A soak time detecting device for detecting a soak time during which the operation of the fuel cell is stopped;
A cathode gas flow rate control device for changing a cathode gas flow rate supplied from the cathode gas supply device according to the soak time when the anode gas is replaced by the anode gas replacement device;
A fuel cell system comprising:   2. The fuel cell system according to claim 1, wherein the cathode gas flow rate control device includes a control map for increasing the cathode gas flow rate as the soak time becomes shorter.   3. The fuel cell system according to claim 1, wherein the cathode gas flow rate control device requires the cathode gas flow rate at the time of OCV when the anode gas passage is scavenged with the cathode gas during soaking. A fuel cell system characterized in that the minimum flow rate is set.   4. The fuel cell system according to claim 1, wherein the cathode gas flow rate control device requires the cathode gas flow rate during anode gas replacement at OCV when the soak time is equal to or longer than a set time. 5. A fuel cell system characterized in that the minimum flow rate is set.   2. The fuel cell system according to claim 1, wherein the cathode gas flow rate control device includes a control map for decreasing the cathode gas flow rate as the soak time becomes shorter.   6. The fuel cell system according to claim 1 or 5, wherein the cathode gas flow rate control device requires the cathode gas flow rate at the time of OCV when the anode gas flow path is scavenged with the cathode gas during soak. The fuel cell system is characterized in that the maximum flow rate is set.   7. The fuel cell system according to claim 1, wherein when the soak time is equal to or longer than a set time, the cathode gas flow rate control device sets the cathode gas flow rate at the time of anode gas replacement to an OCV. The fuel cell system is characterized by setting the maximum flow rate required at times. In the fuel cell system according to any one of claims 1 to 7, means for detecting a remaining amount of anode gas remaining in the fuel cell at the previous stop;
Means for correcting the cathode gas flow rate at the time of anode gas replacement based on the anode gas remaining amount;
A fuel cell system comprising: The fuel cell system according to any one of claims 1 to 8, wherein means for detecting the temperature of the fuel cell at startup;
Means for correcting the cathode gas flow rate at the time of anode gas replacement based on the temperature of the fuel cell;
A fuel cell system comprising: The fuel cell system according to any one of claims 1 to 9, further comprising a cooling medium supply device that supplies a cooling medium to the fuel cell,
The water pump constituting the cooling medium supply device and the air pump constituting the cathode gas supply device are driven coaxially.   11. The fuel cell system according to claim 10, wherein the air pump is driven at a constant rotation. A fuel cell that generates electricity by an electrochemical reaction between a cathode gas supplied to a cathode gas flow channel and an anode gas supplied to an anode gas flow channel, a cathode gas supply device that supplies the cathode gas, and an anode gas that supplies the anode gas A supply device, an anode gas replacement device that replaces the anode gas in the anode gas flow path via the anode gas supply device when the fuel cell is started, and an anode off-gas discharged from the fuel cell. A starting method of a fuel cell system comprising a diluting device for mixing and diluting with a cathode gas supplied from the cathode gas supplying device,
Detecting a soak time during which the operation of the fuel cell is stopped;
A step of changing a cathode gas flow rate supplied from the cathode gas supply device according to the soak time when the anode gas is replaced by the anode gas replacement device;
A starting method for a fuel cell system, comprising:   The start-up method according to claim 12, wherein the cathode gas flow rate is increased as the soak time becomes shorter.   14. The start-up method according to claim 12 or 13, wherein when the anode gas flow path is scavenged with the cathode gas during soak, the cathode gas flow rate at the time of anode gas replacement is set to a minimum flow rate value required at OCV. A method for starting a fuel cell system.   The start-up method according to any one of claims 12 to 14, wherein when the soak time is equal to or longer than a set time, the cathode gas flow rate at the time of anode gas replacement is set to a minimum flow rate value required at OCV. A method for starting a fuel cell system.   13. The start-up method according to claim 12, wherein the cathode gas flow rate is decreased as the soak time becomes shorter.   17. The start-up method according to claim 12 or 16, wherein when the anode gas flow path is scavenged with the cathode gas during soak, the cathode gas flow rate at the time of anode gas replacement is set to a maximum flow rate value required at OCV. A method for starting a fuel cell system.   18. The start-up method according to claim 12, wherein when the soak time is equal to or longer than a set time, the cathode gas flow rate at the time of anode gas replacement is set to a maximum flow rate value required at OCV. And a starting method of the fuel cell system. The start method according to any one of claims 12 to 18, wherein a step of detecting a remaining amount of anode gas remaining in the fuel cell at the previous stop;
Correcting the cathode gas flow rate at the time of anode gas replacement based on the anode gas remaining amount;
A starting method for a fuel cell system, comprising: The method of starting according to any one of claims 12 to 19, wherein the step of detecting the temperature of the fuel cell at the time of startup;
Correcting the cathode gas flow rate during anode gas replacement based on the temperature of the fuel cell;
A starting method for a fuel cell system, comprising:

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