JP2008181768A - Fuel cell system - Google Patents

Abstract

When water is discharged from a fuel gas channel, water can be effectively discharged by supplying higher-pressure fuel gas to the fuel gas channel. Thus, the fuel cell stack can be prevented from being degraded.
A fuel cell stack in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode, the fuel cell stack being stacked with a separator having a fuel gas flow path formed along the fuel electrode, and the fuel gas A first fuel supply line for supplying fuel gas to the flow path, a fuel discharge line for discharging fuel gas from the fuel gas flow path, and whether water clogging in the fuel gas flow path has occurred during steady operation And a control device that supplies higher-pressure fuel gas to the first fuel gas passage when water clogging occurs.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell system.

  Conventionally, since fuel cells have high power generation efficiency and do not emit harmful substances, they have been put into practical use as power generators for industrial and household use, or as power sources for artificial satellites and spacecrafts. Development is progressing as a power source for vehicles such as buses, trucks, passenger carts, and luggage carts. The fuel cell may be an alkaline aqueous solution (AFC), phosphoric acid (PAFC), molten carbonate (MCFC), solid oxide (SOFC), direct methanol (DMFC), etc. Although good, a polymer electrolyte fuel cell (PEMFC) is common.

  In this case, the solid polymer electrolyte membrane is sandwiched between two gas diffusion electrodes and integrated to join. When one of the gas diffusion electrodes is used as a fuel electrode (anode electrode) and hydrogen gas as fuel is supplied to the surface, hydrogen is dissociated into hydrogen ions (protons) and electrons, and the hydrogen ions are converted into a solid polymer electrolyte. Move the membrane. Further, when the other of the gas diffusion electrodes is an oxygen electrode (cathode electrode) and air as an oxidant is supplied to the surface, oxygen in the air is combined with the hydrogen ions and electrons to generate water. The An electromotive force is generated by such an electrochemical reaction.

  In the polymer electrolyte fuel cell, since at least one of the polymer electrolyte membranes needs to be maintained in a wet state, water is supplied to the fuel electrode side and the oxygen electrode side. In this case, moisture moves as proton-entrained water from the fuel electrode side toward the oxygen electrode side, and moves as back diffusion water from the oxygen electrode side toward the fuel electrode side.

However, when moisture stagnates on the fuel electrode side, the hydrogen gas flow path is blocked, hydrogen gas is not supplied to the fuel electrode, and the performance of the fuel cell deteriorates. Therefore, a technique for intermittently exhausting hydrogen gas has been proposed (see, for example, Patent Document 1). Thereby, moisture can be discharged from the hydrogen gas flow path together with the hydrogen gas.
JP 2000-243417 A

  However, in the conventional fuel cell system, since the exhaust pressure is low, moisture cannot be completely discharged from the hydrogen gas flow path. In general, during steady operation of a fuel cell system, it is not necessary to supply a large amount of hydrogen gas to the hydrogen gas flow path, and it is sufficient to supply an amount sufficient to supplement the hydrogen gas consumed for power generation. The hydrogen gas flow path is supplied with relatively low-pressure hydrogen gas. Therefore, even when hydrogen gas is intermittently exhausted, a relatively low-pressure hydrogen gas is supplied to the hydrogen gas channel, so that the effect of the pressure of the hydrogen gas supplied with moisture stagnated in the channel is effective. Could not be discharged.

  The present invention solves the problems of the conventional fuel cell system, and when water is discharged from the fuel gas flow path, a higher pressure fuel gas is supplied to the fuel gas flow path to It is an object of the present invention to provide a fuel cell system that can be effectively discharged, does not hinder the supply of fuel gas to the fuel electrode, and can prevent the performance degradation of the fuel cell stack.

  Therefore, in the fuel cell system of the present invention, a fuel cell in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode is laminated with a separator having a fuel gas flow path formed along the fuel electrode. A fuel cell stack; a first fuel supply line for supplying fuel gas to the fuel gas flow path; a fuel discharge line for discharging fuel gas from the fuel gas flow path; and a fuel gas flow path in steady operation A controller that determines whether or not water clogging has occurred and supplies a higher-pressure fuel gas to the first fuel gas flow path when water clogging has occurred.

  In another fuel cell system of the present invention, a fuel pressure adjusting valve disposed in the first fuel supply pipe for reducing the pressure of the fuel gas from the fuel gas supply source, and bypassing the fuel pressure adjusting valve. The second fuel supply line connected to the first fuel supply line for supplying a higher pressure fuel gas, and disposed in the second fuel supply line and stagnated in the fuel gas flow path A bypass valve set to a pressure at which moisture can be blown away, and the controller opens the bypass valve when the moisture is discharged from the fuel gas flow path.

  In still another fuel cell system according to the present invention, the fuel discharge pipe further includes a first fuel discharge pipe connected to the fuel gas flow path, one end connected to the first fuel discharge pipe, and the other end. A second fuel discharge line connected in the middle of the fuel supply line, and a third fuel discharge line having one end connected to the first fuel discharge line and the other end communicating with the atmosphere. A fuel circulation valve is disposed in the discharge line, a fuel discharge valve is disposed in the third fuel discharge line, and the controller is configured to discharge the fuel from the fuel gas flow path when the fuel is discharged. Close the circulation valve and open the fuel discharge valve.

  According to the structure of Claim 1, a water | moisture content can be discharged | emitted effectively. And supply of the fuel gas to a fuel electrode is not inhibited, and the performance fall of a fuel cell stack can be prevented.

  According to the second aspect of the present invention, when water is discharged from the fuel gas flow path, higher pressure fuel gas can be supplied to the fuel gas flow path simply by opening the bypass valve.

  According to the third aspect of the present invention, when the moisture is discharged from the fuel gas flow path, the fuel circulation valve is closed, and the fuel discharge valve is opened, so that the water is effectively discharged from the fuel gas flow path. be able to.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a fuel cell system according to an embodiment of the present invention.

  In the figure, reference numeral 20 denotes a fuel cell stack as a fuel cell (FC) of the fuel cell system according to the present embodiment, which is used as a power source for vehicles such as passenger cars, buses, trucks, passenger carts, and luggage carts. The Here, the vehicle includes a large number of auxiliary devices that consume electricity, such as a lighting device, a radio, and a power window, which are used even when the vehicle is stopped. Therefore, the fuel cell stack 20 as the power source and the capacitor as the power storage means are used in combination.

  The fuel cell stack 20 may be an alkaline aqueous solution type, phosphoric acid type, molten carbonate type, solid oxide type, direct type methanol, or the like, but is preferably a solid polymer fuel cell. .

  More preferably, PEMFC (Proton Exchange Membrane Fuel Cell) type fuel cell or PEM (Proton Exchange Membrane) using hydrogen gas as fuel gas, that is, anode gas, and oxygen or air as oxidant, that is, cathode gas. ) Type fuel cell. Here, the PEM fuel cell is generally a fuel cell in which a catalyst, an electrode, and a separator are combined on both sides of a solid polymer electrolyte membrane as an electrolyte layer that transmits ions such as protons. Are composed of a plurality of stacks connected in series.

  In the present embodiment, the fuel cell stack 20 has a plurality of cell modules not shown. The cell module includes a unit cell (MEA) as a fuel cell, and a hydrogen gas flow path as an anode gas flow path that is electrically connected to each other and introduced into the unit cell. And a separator for separating the air flow path as the cathode gas flow path as one set, and a plurality of sets are stacked in the thickness direction. In the cell module, unit cells and separators are stacked in multiple stages so that the unit cells are arranged with a predetermined gap (gap) therebetween.

  The unit cell includes an air electrode as an oxygen electrode provided on the side of the solid polymer electrolyte membrane as the electrolyte layer and a fuel electrode provided on the other side. The air electrode includes an electrode diffusion layer made of a conductive material that permeates while diffusing the reaction gas, and a catalyst layer that is formed on the electrode diffusion layer and is supported in contact with the solid polymer electrolyte membrane. In addition, the current collector in contact with the electrode diffusion layer on the air electrode side of the unit cell, and the air electrode side collector as a net-like current collector formed with a large number of openings through which a mixed flow of air and water is transmitted; And a fuel electrode side collector as a net-like current collector for contacting the electrode diffusion layer on the fuel electrode side of the unit cell and leading out current to the outside.

  In the unit cell, water moves. In this case, when a fuel gas, that is, hydrogen gas as an anode gas is supplied into the fuel chamber of the fuel electrode side collector, hydrogen is decomposed into hydrogen ions and electrons, and the hydrogen ions are accompanied by proton-entrained water. Permeates the electrolyte membrane. Further, when the air electrode is used as a cathode electrode and an oxidant, that is, air as a cathode gas, is supplied into an oxygen chamber as an air flow path, oxygen in the air is combined with the hydrogen ions and electrons to form water. Is generated. Moisture permeates through the solid polymer electrolyte membrane as reverse diffusion water and moves into the fuel chamber of the fuel electrode side collector. Here, the reverse diffusion water means that water generated in the oxygen chamber diffuses into the solid polymer electrolyte membrane and permeates into the fuel chamber through the solid polymer electrolyte membrane in the direction opposite to the hydrogen ions. It is a thing.

  FIG. 1 shows an apparatus for supplying hydrogen gas as fuel gas to the fuel cell stack 20. Although hydrogen gas, which is fuel taken out by reforming methanol, gasoline, or the like by a reformer (not shown), can be directly supplied to the fuel cell stack 20, it is stable and sufficient even during high-load operation of the vehicle. In order to be able to supply an amount of hydrogen gas, it is desirable to supply the hydrogen gas stored in the fuel storage means 53. As a result, the hydrogen gas is always sufficiently supplied at a substantially constant pressure, so that the fuel cell stack 20 can follow the fluctuation of the load of the vehicle and supply a necessary current. it can. In this case, the output impedance of the fuel cell stack 20 is extremely low and can be approximated to zero.

  The hydrogen gas is supplied from a fuel storage means 53 as a fuel gas supply source such as a container storing a hydrogen storage alloy, a container storing a hydrogen storage liquid such as decalin, a hydrogen gas cylinder, etc. The fuel is supplied to the inlet of the fuel gas flow path of the fuel cell stack 20 through the pipe 21 and the third fuel supply pipe 33 as the fuel supply pipe connected to the first fuel supply pipe 21. . The first fuel supply pipe 21 is provided with a pressure sensor 27, a fuel pressure adjustment valve 25, and a hydrogen supply valve 26 as a fuel supply electromagnetic valve. In addition, a hydrogen high-pressure supply valve 29 as a bypass valve is disposed in a bypass line 24 as a second fuel supply line that bypasses the fuel pressure regulating valve 25. Further, a safety valve 33 a is disposed in the third fuel supply pipe 33. The number of the pressure sensors 27 and the hydrogen supply valves 26 can be arbitrarily set. The fuel storage means 53 has a sufficiently large capacity and can always supply a sufficiently high pressure of hydrogen gas.

  Then, the hydrogen gas discharged as an unreacted component from the outlet of the fuel gas flow path of the fuel cell stack 20 is discharged out of the fuel cell stack 20 through the first fuel discharge pipe 31. The first fuel discharge pipe 31 is provided with a water recovery drain tank 60 as a recovery container. The water recovery drain tank 60 is connected to a second fuel discharge pipe 30 for discharging hydrogen gas separated from water, and a suction circulation pump 36 as a pump is arranged in the second fuel discharge pipe 30. It is installed. The second fuel discharge pipe 30 is provided with a hydrogen circulation solenoid valve 34 as a fuel circulation valve. The end of the second fuel discharge line 30 opposite to the water recovery drain tank 60 is connected to the third fuel supply line 33. Thereby, the hydrogen gas discharged out of the fuel cell stack 20 can be recovered, supplied to the fuel gas flow path of the fuel cell stack 20 and reused.

  Further, a third fuel discharge pipe 56 is connected to the water recovery drain tank 60, and a hydrogen exhaust electromagnetic valve 62 as a fuel discharge valve is disposed in the third fuel discharge pipe 56, and a fuel cell stack. Hydrogen gas discharged from the fuel gas flow path at the time of starting 20 can be discharged into the atmosphere. The outlet end of the third fuel discharge pipe 56 is connected to the exhaust manifold 51 to dilute the discharged hydrogen with air.

  Further, a fourth fuel discharge line 56 a having the other end connected to the third fuel discharge line 56 is provided between the suction circulation pump 36 and the hydrogen circulation electromagnetic valve 34 in the second fuel discharge line 30. It is connected. The fourth fuel discharge pipe 56a is provided with a reduced-pressure hydrogen discharge valve 62a that is opened when the pressure in the fuel cell stack 20 is reduced. The second fuel discharge conduit 30 is connected to an outside air introduction electromagnetic valve 35 and an air filter 37 so that outside air can be introduced when the fuel cell stack 20 is stopped.

  Here, the fuel pressure adjusting valve 25 is a butterfly valve, a regulator valve, a diaphragm valve, a mass flow controller, a sequence valve, or the like. The pressure of the hydrogen gas flowing out from the outlet of the fuel pressure adjusting valve 25 is set in advance. Any type can be used as long as it can be adjusted to the set pressure. The pressure adjustment may be performed manually, but is preferably performed by an actuator including an electric motor, a pulse motor, an electromagnet, or the like.

  The hydrogen supply valve 26, the hydrogen high pressure supply valve 29, the hydrogen circulation solenoid valve 34, the hydrogen exhaust solenoid valve 62, the decompression hydrogen discharge valve 62a, and the outside air introduction solenoid valve 35 are so-called on-off types, It is actuated by an actuator composed of an electric motor, a pulse motor, an electromagnet or the like. The suction circulation pump 36 may be of any type as long as it can forcibly discharge the reverse diffusion water together with the hydrogen gas to bring the fuel gas flow path into a negative pressure state. Good.

  On the other hand, air as an oxidant is supplied from an air supply fan (not shown) as an oxidant supply source through an intake manifold 54 to an oxygen chamber of the fuel cell stack 20, that is, an air flow path. In this case, the pressure of the supplied air is a normal pressure of about atmospheric pressure. Note that oxygen can be used as the oxidizing agent instead of air. And the air discharged | emitted from an air flow path is discharged | emitted in air | atmosphere through the exhaust manifold 51 and the condenser 52 as a manifold.

  In the present embodiment, the fuel cell system has a control device (not shown). The control device includes arithmetic means such as a CPU and MPU, storage means such as a magnetic disk and a semiconductor memory, an input / output interface, and the like, and is supplied from various sensors to the fuel gas flow path and the air flow path of the fuel cell stack 20. The flow rate of hydrogen, oxygen, air, etc., temperature, output voltage, etc. are detected, and the fuel pressure regulating valve 25, hydrogen supply valve 26, hydrogen high pressure supply valve 29, hydrogen circulation solenoid valve 34, hydrogen exhaust solenoid valve 62, The operation of various valves such as the decompression hydrogen discharge valve 62a and the outside air introduction electromagnetic valve 35 is controlled. Further, the control device is connected to the fuel cell stack 20 in cooperation with other sensors arranged in the vehicle and an EV (Electronic Vehicle) control ECU (Electronic Control Unit) (not shown) as a vehicle control means. And overall control of the operation of all devices supplying the oxidant.

  Next, the operation of the fuel cell system having the above configuration will be described. First, the operation | movement in the starting driving | running started from a stop state is demonstrated.

  First, when the vehicle driver turns on the ignition switch, an activation command is transmitted to the control device, and an operation for activating the fuel cell system is started. In addition, in the state before starting, the hydrogen supply valve 26, the hydrogen high pressure supply valve 29, the hydrogen circulation solenoid valve 34, the hydrogen exhaust solenoid valve 62, and the reduced pressure hydrogen discharge valve 62a are closed. The fuel gas flow path of the fuel cell stack 20 is filled with air as a hydrogen gas replacement gas.

  The control device first operates the air supply fan to supply air to the air flow path of the fuel cell stack 20. Subsequently, the hydrogen exhaust electromagnetic valve 62 is opened, the reduced-pressure hydrogen discharge valve 62a is opened, the suction circulation pump 36 is turned on, and the air in the fuel gas flow path of the fuel cell stack 20 is discharged. The outside air introduction solenoid valve 35 is closed.

  Subsequently, the control device opens the hydrogen high pressure supply valve 29, opens the hydrogen supply valve 26, and waits until a predetermined time elapses. When the predetermined time has elapsed, the hydrogen high-pressure supply valve 29 is closed, and further waiting is performed until the predetermined time elapses.

  Subsequently, when a predetermined time has elapsed, it can be determined that the discharge of air from the fuel gas flow path of the fuel cell stack 20 is completed and the fuel gas flow path is filled with hydrogen gas. Then, the hydrogen exhaust solenoid valve 62 is closed, and the decompression hydrogen discharge valve 62a is closed. When the hydrogen pressure exceeds a predetermined value, the hydrogen circulation solenoid valve 34 is opened, the hydrogen gas discharged outside the fuel cell stack 20 is recovered, supplied to the fuel gas flow path of the fuel cell stack 20, and reused. .

  In addition, after opening the hydrogen circulation solenoid valve 34, the control device determines whether or not the fuel cell voltage exceeds a predetermined value. When the fuel cell voltage exceeds the predetermined value, the control device shifts to a steady operation process. The start operation process is terminated.

  Here, when the fuel cell system is in steady operation, the hydrogen high-pressure supply valve 29 is closed, so that the high-pressure hydrogen gas supplied from the fuel storage means 53 does not pass through the bypass line 24. As indicated by an arrow in FIG. 1, the pressure is reduced by passing through the fuel pressure regulating valve 25 and supplied to the fuel gas flow path of the fuel cell stack 20 via the third fuel supply pipe 33. Therefore, there is no possibility that each part of the fuel cell stack 20 is damaged by the high-pressure hydrogen gas.

  Further, since the hydrogen exhaust solenoid valve 62, the reduced pressure hydrogen discharge valve 62a and the outside air introduction solenoid valve 35 are closed and the hydrogen circulation solenoid valve 34 is opened, the hydrogen gas discharged from the fuel gas flow path of the fuel cell stack 20 is As indicated by the arrows in FIG. 1, the air is drawn by the suction circulation pump 36 and passes through the first fuel discharge conduit 31, the water recovery drain tank 60, the second fuel discharge conduit 30, and the hydrogen circulation solenoid valve 34. Then, the fuel is introduced into the third fuel supply pipe 33, supplied again to the fuel gas flow path of the fuel cell stack 20, and reused.

  On the other hand, when the fuel cell system performs a start-up operation, the high-pressure hydrogen gas supplied from the fuel storage means 53 does not pass through the fuel pressure adjustment valve 25 and therefore is not decompressed and passes through the bypass line 24. Then, the high pressure is supplied to the fuel gas flow path of the fuel cell stack 20 via the third fuel supply pipe 33. Therefore, the air filled in the fuel gas passage can be quickly replaced with hydrogen gas. The hydrogen gas is caused by resistance when passing through valves such as the hydrogen supply valve 26 and the hydrogen high-pressure supply valve 29 and pipes such as the first fuel discharge pipe 31 and the third fuel supply pipe 33. Since each part of 20 is suppressed to a high pressure that does not damage each part, each part of the fuel cell stack 20 is not damaged. Further, since the safety valve 33a is provided in the third fuel supply line 33, each part of the fuel cell stack 20 is reliably damaged by the high-pressure hydrogen gas by appropriately setting the relief pressure of the safety valve 33a. Can be prevented.

  During the operation of the fuel cell stack 20, reverse diffusion water is generated in each unit cell constituting the fuel cell stack 20, and the reverse diffusion water passes through the solid polymer electrolyte membrane and reaches the fuel gas flow path. Then, the fuel electrode side of the solid polymer electrolyte membrane is humidified. As a result, the fuel electrode side of the solid polymer electrolyte membrane becomes wet, and hydrogen ions generated from hydrogen by the electrochemical reaction can move smoothly in the solid polymer electrolyte membrane.

  Further, the hydrogen gas as an unreacted component that is supplied to the fuel gas flow path and surplus is mixed with the back-diffused water that has permeated into the fuel gas flow path and becomes surplus, and a gas-liquid mixture Become. The hydrogen gas that has become the gas-liquid mixture is sucked by the suction circulation pump 36 and discharged to the outside of the fuel cell stack 20 through the first fuel discharge pipe 31 connected to the fuel cell stack 20. The gas-liquid mixture passes through the first fuel discharge pipe 31 and is introduced into the water recovery drain tank 60. By staying in the water recovery drain tank 60 having a relatively wide space, heavy moisture falls downward due to gravity, and the reverse diffusion water is separated from the hydrogen gas. The hydrogen gas in a state where the reverse diffusion water is separated and dried is discharged from the second fuel discharge pipe 30 to the outside of the water recovery drain tank 60, and as described above, the hydrogen circulation solenoid valve which is open. After passing through 34, the fuel is introduced into the third fuel supply pipe 33, supplied again to the fuel gas flow path of the fuel cell stack 20, and reused.

  Next, the operation of the fuel cell system when water is discharged from the fuel gas channel during steady operation will be described.

  FIG. 2 is a diagram showing the operation of the fuel cell system when water is discharged from the fuel gas flow channel according to the embodiment of the present invention. FIG. 3 is a case where water is discharged from the fuel gas flow channel according to the embodiment of the present invention. It is a flowchart which shows operation | movement of the fuel cell system of.

  During the steady operation, the control device determines whether or not there is a stagnation of water in the fuel gas flow path of the fuel cell stack 20 every predetermined cycle, for example, 100 [msec], that is, whether or not there is hydrogen electrode clogging. Detection is performed (step S1), and it is determined whether or not the fuel gas flow path is blocked by moisture, that is, whether or not water clogging has occurred in the hydrogen electrode (step S2). Whether or not the fuel gas flow path is blocked by moisture is determined by measuring the voltage of each unit cell constituting the fuel cell stack 20 as described in, for example, Japanese Patent Application Laid-Open No. 2006-302767. Can be judged by. If the fuel gas flow path is not blocked by moisture, the process is terminated and the above operation is repeated.

  If the fuel gas flow path is blocked by moisture, the control device performs the operation of closing the circulation electromagnetic valve and closes the hydrogen circulation electromagnetic valve 34 (step S3). Subsequently, the control device opens the exhaust solenoid valve and opens the hydrogen exhaust solenoid valve 62 (step S4). Subsequently, the control device opens the start electromagnetic valve and opens the hydrogen high-pressure supply valve 29 (step S5). The operation of opening the exhaust solenoid valve and the operation of opening the start solenoid valve may be performed substantially simultaneously. However, in order to prevent damage to the fuel cell stack, the exhaust solenoid valve is opened with an interval of about 100 [msec]. It is desirable that the opening operation and the start solenoid valve opening operation are sequentially performed in this order.

  As a result, the high-pressure hydrogen gas supplied from the fuel storage means 53 does not pass through the fuel pressure regulating valve 25 and therefore is not depressurized, and passes through the bypass conduit 24 as shown by the arrow in FIG. Thus, the fuel gas is supplied to the fuel gas flow path of the fuel cell stack 20 through the third fuel supply pipe 33 while maintaining the high pressure. Therefore, the water that has stagnated in the fuel gas channel is blown away by the high-pressure hydrogen gas and is reliably discharged out of the fuel gas channel.

  In this case, the hydrogen gas supplied to the fuel gas flow path of the fuel cell stack 20 is higher in pressure than the hydrogen gas supplied to the fuel gas flow path during steady operation, but is supplied to the fuel gas flow path during start-up operation. The pressure is equivalent to that of hydrogen gas. Accordingly, since the pressure of the fuel cell stack 20 is suppressed to such a level as not to damage each portion of the fuel cell stack 20, the hydrogen gas supplied to blow off the water stagnated in the fuel gas flow path is Each part will not be damaged. Further, since the safety valve 33a is provided in the third fuel supply line 33, each part of the fuel cell stack 20 is reliably damaged by the high-pressure hydrogen gas by appropriately setting the relief pressure of the safety valve 33a. Can be prevented.

  The water discharged from the fuel gas flow path is introduced together with hydrogen gas through the first fuel discharge conduit 31 into the water recovery drain tank 60, the hydrogen circulation electromagnetic valve 34 is closed, and the hydrogen exhaust electromagnetic valve Since 62 is opened, it is introduced into the exhaust manifold 51 through the third fuel discharge pipe 56 as indicated by an arrow in FIG. The moisture and hydrogen gas are diluted by the air discharged from the air flow path of the fuel cell stack 20 and discharged into the atmosphere.

  Subsequently, the control device performs the operation of closing the startup electromagnetic valve, and closes the hydrogen high-pressure supply valve 29 (step S6). Subsequently, the control device performs the operation of closing the exhaust solenoid valve, and closes the hydrogen exhaust solenoid valve 62 (step S7). Finally, the control device opens the circulation electromagnetic valve, opens the hydrogen circulation electromagnetic valve 34 (step S8), and ends the process. The operation of the start solenoid valve close, the exhaust solenoid valve close and the circulation solenoid valve open may be performed almost simultaneously, but in order to prevent damage to the fuel cell stack, an interval of about 100 [msec] is opened, It is desirable that the start solenoid valve closing operation, the exhaust solenoid valve closing operation, and the circulation solenoid valve opening operation are sequentially performed in this order.

  Thus, in the present embodiment, when the fuel gas flow path of the fuel cell stack 20 is blocked by moisture, the fuel gas stack 20 does not pass through the fuel pressure regulating valve 25 and thus is not depressurized. As described above, the high-pressure hydrogen gas supplied from the fuel storage means 53 is supplied to the fuel gas passage without passing through the bypass conduit 24 and through the fuel pressure regulating valve 25. Thereby, the water stagnated in the fuel gas channel can be effectively discharged out of the fuel gas channel by blowing off the water with the high-pressure hydrogen gas.

  At the same time, the hydrogen circulation solenoid valve 34 is closed and the hydrogen exhaust solenoid valve 62 is opened, so that moisture discharged from the fuel gas flow path together with hydrogen gas is discharged into the atmosphere through the third fuel discharge pipe 56. be able to.

  Accordingly, the supply of hydrogen gas to the fuel electrode of the fuel cell stack 20 is not hindered by the water stagnating in the fuel gas flow path, and the performance deterioration of the fuel cell stack 20 can be prevented.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is a figure which shows the structure of the fuel cell system in embodiment of this invention. It is a figure which shows operation | movement of the fuel cell system in the case of discharging | emitting water | moisture content from the fuel gas flow path in embodiment of this invention. It is a flowchart which shows operation | movement of the fuel cell system in the case of discharging | emitting water | moisture content from the fuel gas flow path in embodiment of this invention.

Explanation of symbols

20 Fuel cell stack 21 First fuel supply line 24 Bypass line 25 Fuel pressure regulating valve 29 Hydrogen high pressure supply valve 30 Second fuel discharge line 31 First fuel discharge line 33 Third fuel supply line 34 Hydrogen circulation electromagnetic Valve 53 Fuel storage means 56 Third fuel discharge line 62 Hydrogen exhaust solenoid valve

Claims (3)

A fuel cell stack in which an electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode, and is stacked with a separator having a fuel gas flow path formed along the fuel electrode;
A first fuel supply line for supplying fuel gas to the fuel gas flow path;
A fuel discharge line for discharging fuel gas from the fuel gas flow path;
A controller that determines whether water clogging has occurred in the fuel gas flow path during steady-state operation and supplies higher pressure fuel gas to the first fuel gas flow path in the event of water clogging; A fuel cell system. A fuel pressure regulating valve disposed in the first fuel supply line and depressurizing fuel gas from a fuel gas supply source;
A second fuel supply line connected to the first fuel supply line to bypass the fuel pressure regulating valve and for supplying a higher pressure fuel gas;
A bypass valve that is disposed in the second fuel supply pipe and is set to a pressure that blows away water stagnated in the fuel gas flow path;
The fuel cell system according to claim 1, wherein the control device opens the bypass valve when water is discharged from the fuel gas flow path. The fuel discharge line includes a first fuel discharge line connected to the fuel gas flow path, a second fuel discharge whose one end is connected to the first fuel discharge line and the other end is connected in the middle of the fuel supply line. A pipe and a third fuel discharge pipe having one end connected to the first fuel discharge pipe and the other end communicating with the atmosphere;
A fuel circulation valve is disposed in the second fuel discharge conduit,
A fuel discharge valve is disposed in the third fuel discharge line,
2. The fuel cell system according to claim 1, wherein the controller closes the fuel circulation valve and opens the fuel discharge valve when water is discharged from the fuel gas passage. 3.

Images