JP2004296340A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent discharge of high-concentration hydrogen in system stop with a simple structure. <P>SOLUTION: This fuel cell system is equipped with: a fuel cell stack 1 for generating power by being supplied with a plurality of fluids including at least a fuel gas and an oxidizer gas; respective systems formed on the fluid entrance side of the stack 1 for supplying the respective fluids to the stack 1, and formed on the fluid exit side of the fuel cell stack for discharging the respective fluids having passed the fuel cell stack; and shutoff valves 5, 8, 11, 16, 20, 22, 24 and 26 installed in respective fluid supply passages on the fluid entrance side of the stack 1 and in respective fluid discharge passages of the fluid exit of the fuel cell stack; and the respective shutoff valves are brought into an open state in normal operation. In stopping the operation of the system, the respective shutoff valves 5, 8, 11, 16, 20, 22, 24 and 26 are closed, the respective fluids are shutoff between the shutoff valves of the respective fluid supply passages and the shutoff valves of the respective fluid discharge passages, and thereafter the respective fluids are gradually discharged. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell system for supplying a plurality of types of fluids such as hydrogen and air to a fuel cell stack to generate power.
[0002]
[Prior art]
Conventionally, in a fuel cell system including a fuel cell stack that generates power using hydrogen as a fuel gas, at the time of an emergency stop of the system, by opening a nitrogen supply valve prior to a shutoff operation of a hydrogen shutoff valve, A technique for reliably diluting hydrogen is known from Patent Document 1 below.
[0003]
[Patent Document 1]
JP-A-9-293522
[0004]
[Problems to be solved by the invention]
However, the above-described conventional fuel cell system has an advantage that hydrogen dilution is not delayed, but on the other hand, it must have a nitrogen cylinder, so that the whole system becomes expensive and there is a problem in layout when mounted on a vehicle, for example. .
[0005]
Therefore, the present invention has been proposed in view of the above-described circumstances, and has a simple configuration and can prevent a large amount of high-concentration hydrogen from being discharged at once when the system is stopped. The purpose is to provide a system.
[0006]
[Means for Solving the Problems]
In the present invention, a fuel cell stack that is supplied with a plurality of fluids including at least a fuel gas and an oxidizing gas to generate electric power, and for each of the fluids, is provided on a fluid inlet side of the fuel cell stack and uses A plurality of fluid supply systems each having a fluid supply flow path for supplying a stack, a fluid discharge flow path provided on a fluid outlet side of the fuel cell stack and discharging each fluid passing through the fuel cell stack, A shutoff valve is provided in each of the supply flow path and each of the fluid discharge flow paths, and each of the shutoff valves is kept open during normal operation.
[0007]
In this fuel cell system, when the operation of the system is stopped, the respective shut-off valves are closed, and each fluid is gradually confined between the shut-off valve of each fluid supply flow passage and the shut-off valve of each fluid discharge flow passage. The above-mentioned problem is solved by discharging each fluid.
[0008]
【The invention's effect】
According to the fuel cell system of the present invention, when the operation of the system is stopped, each fluid is confined between the shut valves by closing the shut valves provided at the fluid inlet and the fluid outlet of the fuel cell stack. Is gradually discharged, so that a large amount of high-concentration hydrogen can be prevented from being discharged at once with a simple configuration without using a nitrogen cylinder or the like for diluting the fuel gas.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
The present invention is applied to, for example, a fuel cell system configured as shown in FIG.
[0011]
[Configuration of fuel cell system]
As shown in FIG. 1, the fuel cell system includes a fuel cell stack 1 that generates power by being supplied with a fuel gas and an oxidizing gas. The fuel cell stack 1 is configured by, for example, sandwiching a fuel cell structure in which an air electrode and a hydrogen electrode are opposed to each other with a solid polymer electrolyte membrane interposed therebetween and a separator, and stacking a plurality of cell structures. . In the present embodiment, a description will be given of a fuel cell system that supplies hydrogen gas to the hydrogen electrode as a fuel gas for causing the fuel cell stack 1 to generate a power generation reaction, and supplies air containing oxygen as an oxidant gas to the air electrode. .
[0012]
In this fuel cell system, an air system that supplies air to the fuel cell stack 1 and guides the air discharged from the fuel cell stack 1 to the combustor 2, supplies hydrogen gas to the fuel cell stack 1, and supplies hydrogen gas to the fuel cell stack 1 The temperature of the hydrogen gas system for guiding the discharged hydrogen gas to the combustor 2, the pure water system for circulating air supplied to the fuel cell stack 1 and the humidifying pure water for humidifying the hydrogen gas, and the temperature of the fuel cell stack 1 are adjusted. A cooling water system for circulating cooling water is provided. In this fuel cell system, when controlling the power generation of the fuel cell stack 1, the control unit 3 controls the flow rate and pressure of each fluid of air, hydrogen gas, pure water for humidification, and cooling water.
[0013]
In the air system, an air compressor 4, an air humidifier inlet shut-off valve 5, and a humidifier 6 are provided in an air supply passage L1, and an air pressure regulating valve 7 is provided in an air discharge passage L2 on the air discharge side of the fuel cell stack 1. , An air stack outlet shut-off valve 8 and the combustor 2 are provided. During normal operation of the fuel cell system, the control unit 3 adjusts the number of revolutions of the air compressor 4 and the opening of the air pressure regulating valve 7 so that the air flow and the air supplied to the fuel cell stack 1 are controlled. The pressure is adjusted, the outside air is taken in by the air compressor 4, the air is guided to the humidifier 6, the humidified air is supplied to the fuel cell stack 1, and the air discharged from the fuel cell stack 1 is guided to the combustor 2. .
[0014]
In this air system, the operation of the air humidifier inlet shut-off valve 5 and the air stack outlet shut-off valve 8 is controlled by the control unit 3 during an emergency stop of the fuel cell system.
[0015]
In the hydrogen gas system, a hydrogen tank 9, a hydrogen pressure regulating valve 10, a hydrogen humidifier inlet shut valve 11, and a humidifier 6 are provided in a hydrogen supply flow path L3. This hydrogen gas system guides the hydrogen stored in the hydrogen tank 9 to the fuel cell stack 1 as hydrogen gas during normal operation of the fuel cell system. At this time, in the hydrogen gas system, the hydrogen pressure and the hydrogen flow rate are adjusted by adjusting the opening of the hydrogen pressure regulating valve 10 by the control unit 3.
[0016]
In addition, the hydrogen gas system is provided on the hydrogen discharge side of the fuel cell stack 1 with a hydrogen circulation flow path L4 for returning the hydrogen gas discharged from the fuel cell stack 1 to the fuel cell stack 1 again. The vessel 2 is provided with a hydrogen discharge channel L5 for discharging hydrogen gas and a purge channel L6 for purging hydrogen gas. A hydrogen circulation system shut valve 12 and a hydrogen circulation pump 13 are provided in the hydrogen circulation channel L4, and an outside air suction valve 14 is provided in a branched outside air suction channel L7. The hydrogen discharge flow path L5 is provided with a hydrogen discharge opening variable valve 15 and a hydrogen stack outlet shutoff valve 16, and the purge flow path L6 is provided with a purge valve 17.
[0017]
In such a hydrogen gas system, during normal operation of the fuel cell system, the hydrogen circulation pump 13 is driven by the control unit 3 to reuse the hydrogen gas, and the purge valve 17 is opened when necessary. Is done. In the hydrogen gas system, the operations of the hydrogen stack outlet shutoff valve 16, the hydrogen circulation system shutoff valve 12, and the outside air intake valve 14 are controlled by the control unit 3 when the fuel cell system is stopped in an emergency.
[0018]
The humidifying pure water system includes a humidifying pure water tank 18, a humidifying pure water pump 19, a pure water humidifier inlet shut valve 20, a humidifier 6, a pure water discharge opening variable valve 21, and a pure water circulating passage L8. A water humidifier outlet shut valve 22 is provided. During the normal operation of the fuel cell system, the control unit 3 adjusts the rotation speed of the humidification pure water pump 19 and the opening of the pure water discharge opening variable valve 21 in the humidification pure water system. By sending the pure water for humidification accumulated in 18 to the humidifier 6, the air and the hydrogen gas supplied to the fuel cell stack 1 are humidified. In the humidifying pure water system, the operation of the pure water humidifier inlet shutoff valve 20 and the pure water humidifier outlet shutoff valve 22 is controlled by the control unit 3 during an emergency stop of the fuel cell system.
[0019]
The cooling water system includes a cooling water circulation passage L9, a stack cooling water pump 23, a cooling water stack inlet shutoff valve 24, a fuel cell stack 1, a cooling water discharge opening adjustment valve 25, a cooling water stack outlet shutoff valve 26, and a cooling water. A radiator bypass three-way valve 27, a radiator 28, and a blower fan 29 are provided. During the normal operation of the fuel cell system, the cooling water system is controlled by the control unit 3 to drive the stack cooling water pump 23, to open the cooling water discharge opening adjustment valve 25, and to control the cooling water radiator bypass three-way valve 27. The operation and the driving amount of the blower fan 29 are adjusted, and the temperature of the cooling water supplied from the stack cooling water pump 23 to the fuel cell stack 1 is adjusted to an appropriate value. In the cooling water system, the operation of the cooling water stack inlet shutoff valve 24 and the cooling water stack outlet shutoff valve 26 is controlled by the control unit 3 when the fuel cell system is stopped in an emergency.
[0020]
Further, this fuel cell system has a stack accommodating portion 1A for accommodating the fuel cell stack 1, and adjusts the temperature and humidity inside the stack accommodating portion 1A to adjust the temperature and humidity around the fuel cell stack 1. A ventilation system for supplying air to the periphery of the fuel cell stack 1 and performing ventilation is provided in order to set an appropriate value. This ventilation system is configured such that a stack ventilation blower 30, a stack accommodation section 1A, and a ventilation blower line three-way valve 31 are provided in an air flow path L10. This ventilation system adjusts the driving amount of the stack ventilation blower 30 during normal operation of the fuel cell system, and also ventilates the air discharged through the stack accommodating section 1A to the atmosphere. Operate the valve 31.
[0021]
Further, in this fuel cell system, as shown in FIG. 2, a discharge resistor 41 can be connected to the fuel cell stack 1, and a converter 42 and a secondary battery 43 are connected in parallel with the fuel cell stack 1. In this fuel cell system, during normal operation, the electric power generated by the fuel cell stack 1 is taken out by the converter 42 and supplied to loads such as a drive motor and auxiliary equipment (not shown), and if necessary, the secondary battery. 43 is charged and discharged.
[0022]
During normal operation of the fuel cell system thus configured, the control unit 3 includes the air stack inlet pressure sensor 51 provided in the air supply passage L1 and the hydrogen stack inlet pressure sensor provided in the hydrogen supply passage L3. 52, a sensor signal from a pure water humidifier inlet pressure sensor 53 provided in the pure water circulation flow path L8, and a cooling water stack inlet pressure sensor 54 provided in the cooling water circulation flow path L9. The rotation speeds of the circulation pump 13, the humidified pure water pump 19, the stack cooling water pump 23, and the stack ventilation blower 30 are monitored. Then, the control unit 3 refers to the sensor signals from the respective sensors according to the generated power required for the fuel cell stack 1, and refers to the flow rates of the respective fluids of air, hydrogen gas, humidifying pure water, and cooling water. A control signal for controlling the pressure is sent to each unit.
[0023]
The control unit 3 executes an emergency stop process for stopping the fuel cell system when the fuel cell system is emergency stopped for some reason. The details of the emergency stop process will be described later.
[0024]
[Emergency stop processing]
Next, the processing procedure of the emergency stop processing in the fuel cell system configured as described above will be described with reference to the flowchart of FIG.
[0025]
The control unit 3 starts the processing after step S1 when the fuel cell system is emergency stopped for some reason. First, in step S1, the air humidifier inlet shut valve 5, the hydrogen humidifier inlet shut valve 11, the air The stack outlet shut-off valve 8, hydrogen stack outlet shut-off valve 16, pure water humidifier inlet shut-off valve 20, pure water humidifier outlet shut-off valve 22, cooling water stack inlet shut-off valve 24 and cooling water stack outlet shut-off valve 26 are simultaneously closed. As a result, each fluid is confined in the flow path between the shut valves at substantially the same pressure as the operation state at the time when step S1 was started. In this emergency stop processing, the purge valve 17 is also closed as in the normal operation.
[0026]
When the process of step S1 is performed in this manner, as shown in FIG. 4, for example, when an emergency stop is performed at time t1, each of the shut valves 5, 8, 11, 16, 20, 22, 24, and 26 is closed. As a result, each fluid is confined, and the hydrogen pressure, air pressure, stack cooling water pressure, and humidifying pure water pressure become constant values that are substantially the same as those in the normal operation.
[0027]
In the next step S2, the discharge resistor 41 is connected to the fuel cell stack 1, and the voltage (residual voltage) remaining in the fuel cell stack 1 is discharged by the discharge resistor 41 and reduced. This is because when the state where the residual voltage exists in the fuel cell stack 1 is left for a long time even though the power generation of the fuel cell stack 1 is stopped, deterioration of the polymer film in the fuel cell stack 1 is suppressed. It is. As described above, when the state in which the residual voltage exists is for a long time, for example, when the secondary battery 43 is not charged enough to execute the emergency stop process described below, the emergency stop process is performed. This is the case when time is needed to move to a location where an external power source is available.
[0028]
In the next step S3, the control unit 3 determines whether or not the electric power for executing the operation mode described later is charged in the secondary battery 43, thereby reducing the pressure difference between the fluids in each system. It is determined whether or not it is possible to start an operation mode for discharging hydrogen (hydrogen discharge mode) while keeping the pressure within a preset allowable value. If it is determined that the hydrogen discharge mode cannot be started, the process proceeds to step S4, whereas if it is determined that the hydrogen discharge mode can be started, the process proceeds to step S5.
[0029]
In step S4, the control unit 3 notifies the driver to supply an external power supply for executing the hydrogen discharge mode, prompts the driver to charge the secondary battery 43, and proceeds to step S3. return.
[0030]
Also, in step S5, the control unit 3 notifies the driver that the hydrogen discharge mode can be started, and when the driver gives an instruction to permit the start of the hydrogen discharge mode in response to the notification. Move to step S6. Here, when notifying the driver that the hydrogen discharge mode can be started, an instruction to permit the start of the hydrogen discharge mode is provided by, for example, a button (not shown) using a display mechanism or a sound emitting mechanism (not shown). The operation of the operation mechanism such as is detected. Not only when prompting the driver to give an instruction to start the hydrogen discharge mode as described above, but also when the secondary battery 43 is sufficiently charged, the process automatically shifts to the processing after step S6. You may.
[0031]
In step S6, the control unit 3 reads sensor signals from the air stack inlet pressure sensor 51, the hydrogen stack inlet pressure sensor 52, the pure water humidifier inlet pressure sensor 53, and the cooling water stack inlet pressure sensor 54, and reads each sensor signal. From the respective pressure values corresponding to the air pressure regulating valve 7, the opening degree variable valve 15 for discharging hydrogen, the opening degree variable valve 21 for discharging pure water, the opening degree adjusting valve 25 for discharging cooling water, the stack ventilation blower 30 Is determined and driven. By determining the rotation speed of the stack ventilation blower 30 in this manner, the control unit 3 determines the flow rate of the air supplied to the combustor 2 via the ventilation blower line three-way valve 31, and removes hydrogen when discharging hydrogen. Determine the air flow rate for dilution.
[0032]
In the next step S7, the control unit 3 controls the ventilation blower line three-way valve 31 to be closed with respect to the atmosphere and open with respect to the combustor 2. Then, in step S7, the hydrogen stack outlet shut valve 16 is opened, and the hydrogen gas in the flow path from the hydrogen humidifier inlet shut valve 11 to the hydrogen stack outlet shut valve 16 and in the hydrogen circulation flow path L4 is The hydrogen is sent to the combustor 2 at the opening degree of the opening degree variable valve 15 for hydrogen discharge driven in step S6. Thus, in the combustor 2, the hydrogen sent through the hydrogen stack outlet shut-off valve 16 is mixed and diluted with the air supplied through the ventilation blower line three-way valve 31. At this time, the combustor 2 functions as a mixer for mixing hydrogen gas with air.
[0033]
In the next step S8, the control unit 3 opens the air stack outlet shut-off valve 8, the pure water humidifier outlet shut-off valve 22, and the cooling water stack outlet shut-off valve 26, and sets the air stack inlet pressure sensor 51, hydrogen Referring to the sensor signals from the stack inlet pressure sensor 52, the pure water humidifier inlet pressure sensor 53, and the cooling water stack inlet pressure sensor 54, the air pressure regulating valve 7 and the pure water The opening of the water discharge opening variable valve 21 and the cooling water discharge opening adjustment valve 25 is adjusted. As a result, the air of the air system is started to be discharged to the combustor 2, the cooling water of the cooling water system is started to be discharged to the radiator 28 and the like, and the pure water for humidification of the pure water system for humidification is started to be discharged to the humidified pure water tank 18. .
[0034]
Here, step S8 is executed substantially simultaneously with step S7, so that hydrogen is combusted via the hydrogen discharge opening variable valve 15 and the hydrogen stack outlet shut valve 16 as shown after time t2 in FIG. The control unit 3 controls the air pressure, the cooling water pressure, and the pure water pressure for humidification with a gradient substantially the same as the gradient of the hydrogen pressure due to the discharge to the vessel 2 with reference to the sensor signals. Further, the control unit 3 controls the opening degree of each valve so that the pressure difference between the respective fluids falls within the allowable differential pressure.
[0035]
In the next step S9, the control unit 3 monitors the sensor signal from the hydrogen stack inlet pressure sensor 52, and continues to discharge each fluid as shown in FIG. 4, whereby the pressure of each fluid gradually decreases. When it is detected that the hydrogen gas pressure has decreased to the atmospheric pressure at time t3 in FIG. 3, the process proceeds to step S10.
[0036]
In step S10, the control unit 3 controls the air stack outlet shut-off valve 8, the pure water humidifier outlet shut-off valve 22 and the cooling water stack outlet shut-off valve 26 to a closed state, so that the fuel cell stacks other than the hydrogen gas system are controlled. The movement of the fluid at the first fluid outlet and the fluid outlet of the humidifier 6 is stopped.
[0037]
In the next step S11, the replacement of residual hydrogen in the hydrogen gas system with air is started.
[0038]
In step S12, the control unit 3 closes the hydrogen circulation system shut valve 12 and opens the outside air suction valve 14.
[0039]
In the next step S13, by starting the hydrogen circulation pump 13 by the control unit 3, air is taken in from the outside air intake valve 14 to replace hydrogen with air. At this time, the control unit 3 sends the hydrogen gas, the air, the cooling water, and the pure water for humidification to the combustor 2 from the stack ventilation blower 30 to the head in a range in which the pressure difference falls within the allowable differential pressure. The hydrogen circulation pump 13 is driven so that the air sent to the combustor 2 with the supplied air has an air flow rate that can be diluted to a value equal to or lower than the combustible region.
[0040]
In the next step S14, the control unit 3 refers to the sensor signal from the hydrogen stack inlet pressure sensor 52 and adjusts the pressure of the hydrogen gas system so that the pressure difference from the pressure of the other system is within the allowable pressure difference. In order to adjust, the opening degree of the hydrogen discharge opening degree variable valve 15 is adjusted.
[0041]
In the next step S15, the control unit 3 stops the driving of the hydrogen circulation pump 13 after a certain period of time from the start of the replacement of the hydrogen gas system with air in step S13, and turns off the hydrogen stack outlet shut-off valve 16. The process is terminated by closing the state. Here, the certain time is a time obtained from the volume of the hydrogen gas system and the flow rate of the hydrogen circulation pump 13 at the time of air replacement.
[0042]
[Effects of Embodiment]
As described above in detail, according to the fuel cell system to which the present invention is applied, the shut-off valves 5, 8, 11, 16, 16 provided at the fluid inlet and the fluid outlet of the fuel cell stack 1 during an emergency stop of the system. After closing the fluids between the shut-off valves by closing 20, 22, 24, and 26, each fluid is discharged while gradually reducing its pressure, and air is sent from the stack ventilation blower 30 to the combustor 2. Thus, the combustible hydrogen can be diluted with air while gradually discharging the combustible hydrogen to the combustor 2. Therefore, according to this fuel cell system, it is possible to prevent a large amount of high-concentration hydrogen from being discharged at once with a simple configuration without using a nitrogen cylinder or the like for diluting hydrogen.
Further, according to this fuel cell system, since the shut-off valves 5, 8, 11, 16, 20, 22, 24, and 26 are simultaneously closed, each fluid is confined in a state substantially equal to the pressure during normal operation. Accordingly, each fluid can be discharged while maintaining the pressure of each fluid within the allowable differential pressure, and the fuel cell stack 1 can be prevented from being damaged due to a difference in the manner in which the pressure of each fluid decreases.
[0043]
Further, according to this fuel cell system, the cooling water circulation passage L9 is provided with the cooling water stack inlet shutoff valve 24 and the cooling water stack outlet shutoff valve 26 to discharge the cooling water similarly to the hydrogen gas system and the air system. Since the pressure is reduced, it is possible to prevent the fuel cell stack 1 from being damaged due to the differential pressure between the cooling water and hydrogen or air, and to further improve the reliability of the fuel cell stack 1 during an emergency stop. Can be.
[0044]
Furthermore, according to this fuel cell system, the discharge resistor 41 is connected to the fuel cell stack 1 while each fluid is confined in each system, and the residual voltage of the fuel cell stack 1 is reduced. Even when it takes time to discharge hydrogen, such as when the secondary battery 43 is unusable, it is possible to prevent the polymer membrane of the fuel cell stack 1 from deteriorating.
[0045]
Furthermore, according to this fuel cell system, the driver can be notified that the hydrogen discharge mode can be performed after step S5, so that the driver can select the place and timing for performing the hydrogen discharge mode. Can be done.
[0046]
Furthermore, according to this fuel cell system, the combustor 2 can be used as a mixer for mixing the air from the stack ventilation blower 30 and the hydrogen gas from the hydrogen gas system. Hydrogen gas can be reliably diluted and discharged with a simpler configuration without additional components, and the reliability of emergency stop of the system is further improved while reducing the cost and improving the layout of the system. be able to.
[0047]
Furthermore, according to this fuel cell system, the combustor 2 of hydrogen gas used for purging during normal operation can be used as a mixer, and it is simpler without adding a new mixer. With such a configuration, the hydrogen gas can be reliably diluted and discharged, and the reliability of the emergency stop of the system can be further improved while realizing the cost reduction and the layout improvement of the system.
[0048]
Furthermore, according to this fuel cell system, the bypass ventilation flow path is provided for diverting the air from the stack ventilation blower 30 to the combustor 2 and discharging the air to the atmosphere during normal operation. It is possible to prevent the combustion performance of the combustor 2 from being lowered without lowering the temperature of the combustor 2 by the air from the air conditioner 30.
[0049]
Furthermore, according to this fuel cell system, the rotation of the stack ventilation blower 30 is referred to by referring to the pressure of each fluid when the shut valves 5, 8, 11, 16, 20, 22, 24, and 26 are closed. The number can be determined to determine the optimal flow rate of the air to be supplied to the combustor 2, and the power consumption of the stack ventilation blower 30 can be suppressed to a minimum.
[0050]
Furthermore, according to this fuel cell system, after the hydrogen pressure of the hydrogen gas system drops to near the atmospheric pressure, the hydrogen circulation pump 13 is driven to take in air from the outside air suction valve 14 to thereby remove hydrogen in the hydrogen gas system. The air is replaced with air, and the replaced hydrogen gas is diluted with air in the combustor 2, so that it is possible to reliably suppress the hydrogen from remaining in the fuel cell stack 1, and to reduce the fuel cell stack 1 due to the residual hydrogen. Deterioration can be suppressed.
[0051]
Furthermore, according to this fuel cell system, the air pressure regulating valve 7, the hydrogen discharge opening variable valve 15, and the cooling water discharge opening adjustment capable of continuously adjusting the opening on the fluid outlet side of the fuel cell stack 1. Since the valve 25 is provided and the pure water discharge opening variable valve 21 is provided on the fluid outlet side of the humidifier 6, the opening of each valve can be increased to discharge each fluid, and each fluid can be discharged in a short time. Can be discharged.
[0052]
Furthermore, according to this fuel cell system, each valve 7, 15, 21 is referred to by referring to the pressure of each fluid in a state where the shut valves 5, 8, 11, 16, 20, 22, 24, 26 are closed. , 25 are determined, so that the concentration of the hydrogen gas to be discharged is reliably diluted to below the flammable range, and the discharge of the hydrogen gas is completed in a short time, regardless of the operation state immediately before the emergency stop state. be able to.
[0053]
Furthermore, according to this fuel cell system, when gradually discharging each fluid by a small amount, each valve 7 is controlled so that the differential pressure between the fluids is within an allowable value while referring to the pressure of each fluid. , 15, 21, and 25, the damage of the fuel cell stack 1 and the humidifier 6 due to the differential pressure can be more reliably prevented.
[0054]
Furthermore, according to this fuel cell system, a pure water humidifier inlet shut-off valve 20 and a pure water humidifier outlet shut-off valve 22 are provided in the pure water circulating flow path L8, and humidification is performed similarly to the hydrogen gas system and the air system. Since the pressure is reduced by discharging the pure water, it is possible to prevent the humidifier 6 from being damaged due to the pressure difference between the pure water for humidification and hydrogen or air. Can be further improved.
[0055]
Note that the above embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and other than the present embodiment, various modifications may be made according to the design and the like within a range not departing from the technical idea according to the present invention. Can be changed.
[0056]
That is, in the above-described embodiment, it has been described that the present embodiment is particularly effective at the time of an emergency stop in which the supply of the hydrogen gas also needs to be stopped. However, the processing of steps S1 to S15 may be performed at the time of the normal stop. Of course.
[0057]
In the above-described embodiment, the case where the fluid supplied to the fuel cell stack 1 is hydrogen gas, air, pure water for humidification, and cooling water has been described. Even when the fluid to be used is only the hydrogen gas and the oxidizing gas, the same effect can be obtained by performing the above-described emergency stop processing.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a fuel cell system to which the present invention is applied.
FIG. 2 is a block diagram showing an electrical configuration of a fuel cell system to which the present invention is applied.
FIG. 3 is a flowchart showing a processing procedure when performing an emergency stop processing in a fuel cell system to which the present invention is applied.
FIG. 4 is a diagram showing temporal changes in hydrogen gas pressure, air pressure, cooling water pressure and humidification pure water pressure when an emergency stop process is performed in a fuel cell system to which the present invention is applied.
[Explanation of symbols]
1 Fuel cell stack
1A Stack storage section
2 Combustor
3 Control unit
4 Air compressor
5. Air humidifier inlet shut-off valve
6 humidifier
7 Air pressure regulating valve
8 Air stack outlet shut-off valve
9 Hydrogen tank
10 Hydrogen pressure regulating valve
11 Hydrogen humidifier inlet shut-off valve
12. Hydrogen circulation system shut-off valve
13 Hydrogen circulation pump
14 Outside air intake valve
15 Variable opening valve for hydrogen discharge
16 Hydrogen stack outlet shut-off valve
17 Purge valve
18 humidified pure water tank
19 Humidifying pure water pump
20 Pure water humidifier inlet shut-off valve
21 Variable opening valve for pure water discharge
22 Pure water humidifier outlet shut valve
23 Stack cooling water pump
24 Cooling water stack inlet shut-off valve
25 Cooling water discharge opening adjustment valve
26 Cooling water stack outlet shut-off valve
27 Three-way valve for cooling water radiator bypass
28 Radiator
29 blower fan
30 Stack ventilation blower
31 Ventilation blower line three-way valve
41 Discharge resistance
42 Converter
43 Secondary battery
51 Air stack inlet pressure sensor
52 Hydrogen stack inlet pressure sensor
53 Pure water humidifier inlet pressure sensor
54 Cooling water stack inlet pressure sensor
L1 air supply channel
L2 air discharge channel
L3 hydrogen supply channel
L4 hydrogen circulation channel
L5 hydrogen discharge channel
L6 purge channel
L7 Outside air suction channel
L8 Pure water circulation channel
L9 Cooling water circulation channel
L10 air flow path

Claims (13)

A fuel cell stack that is supplied with a plurality of fluids including at least a fuel gas and an oxidant gas to generate power,
For each of the fluids, a fluid supply channel provided on the fluid inlet side of the fuel cell stack and supplying each fluid to the fuel cell stack, and passing through the fuel cell stack provided on the fluid outlet side of the fuel cell stack A plurality of fluid supply systems having a fluid discharge flow path for discharging each of the fluids,
A shut valve provided in each of the fluid supply channels and each of the fluid discharge channels,
When shutting down the system, the shut valves are closed, each fluid is confined between the shut valve of each fluid supply channel and the shut valve of each fluid discharge channel, and then each fluid is gradually discharged. And a fuel cell system. The fuel cell system according to claim 1, wherein the fluid includes cooling water for adjusting a temperature of the fuel cell stack. While each fluid is confined between the shut valve of each fluid supply channel and the shut valve of each fluid discharge channel, a discharge resistor is connected to the fuel cell stack to reduce the residual voltage of the fuel cell stack. The fuel cell system according to claim 1, wherein the fuel cell system is discharged. Further comprising a secondary battery for discharging and charging power,
While each fluid is confined between the shut valve of each fluid supply flow path and the shut valve of each fluid discharge flow path, the secondary battery is gradually charged with power used to discharge each fluid. 2. The fuel cell system according to claim 1, wherein it is determined whether or not the discharge is performed, and the start of discharge of each fluid is notified. 3. A blower for ventilation for supplying air around the fuel cell stack,
It further comprises a mixer for mixing the air supplied from the blower through the periphery of the fuel cell stack and the fuel gas discharged through the fluid discharge passage to dilute the fuel gas. The fuel cell system according to claim 1, wherein: The fuel cell system according to claim 5, wherein a combustor that burns fuel gas discharged from the fuel cell stack during normal operation of the system is used as the mixer. 7. The fuel cell system according to claim 6, further comprising a flow path for discharging the air supplied from the blower by bypassing the combustor. The rotation speed of the blower is determined based on the pressure of each fluid confined between a shut valve of each fluid supply channel and a shut valve of each fluid discharge channel, according to claim 5, wherein: A fuel cell system as described. A fuel circulation pump that returns a fuel gas discharged from the fuel cell stack to a fuel gas inlet of the fuel cell stack;
After the fuel gas is gradually discharged and the fuel gas pressure is reduced to substantially the atmospheric pressure, outside air is taken in by the fuel circulation pump, and the circulation flow path, the fuel gas fluid supply flow path and the fuel discharge flow path The fuel cell system according to claim 5, wherein the fuel gas is replaced with air, and the fuel gas is diluted with the air of the blower. 2. The fuel cell system according to claim 1, further comprising an opening variable valve capable of continuously changing an opening on a fluid outlet side of the fuel cell stack. Based on the pressure of each fluid confined between the shut valve of each fluid supply passage and the shut valve of each fluid discharge passage, the opening of the variable opening valve is determined, and each fluid is gradually settled. The fuel cell system according to claim 10, wherein the fuel cell system is discharged. Based on the pressure of each fluid confined between the shut valve of each fluid supply passage and the shut valve of each fluid discharge passage, the opening degree is adjusted so that the difference between the pressures of the respective fluids is within an allowable value. 11. The fuel cell system according to claim 10, wherein the degree of opening of the variable valve is determined, and each fluid is gradually discharged. Humidifier for humidifying at least one of the fuel gas and the oxidizing gas using humidifying water,
A humidifying water circulation channel for circulating humidifying water to the humidifier,
The humidifier further includes a humidification water inlet and a humidification water shutoff valve provided in the humidification water circulation flow path of the humidification water outlet, respectively.
When the operation of the system is stopped, the respective humidifying water shut valves are closed, the humidifying water is confined between the respective humidifying water shut valves, and the respective fluids are gradually discharged, and the humidifying water is gradually discharged. The fuel cell system according to claim 1.

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