JP2008293756A - Fuel cell system and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system quickly raising catalyst temperature at starting of the system and capable of reducing exhaust of unburned fuel gas, and to provide the operation method of the fuel cell system. <P>SOLUTION: The fuel cell system 1 includes a fuel cell stack 10; a coolant circulation system for circulating a coolant through the fuel cell stack 10; a catalytic combustor 70 for heating circulating coolant; and a compressor 31 supplying air to the fuel cell stack 10 and the catalytic combustor 70, wherein the fuel cell stack 10 and the catalytic combustor 70 are installed in parallel to the compressor 31, and when the fuel cell stack 10 is warmed up at system starting, the catalytic combustor 70 warms up the fuel cell stack 10 through the coolant. The fuel cell system 1 further includes an ECU 90 for deciding whether the warming up of the fuel cell stack 10 is completed or not, and after completion of warming up is decided, the compressor 31 supplies air to the catalytic combustor 70 to scavenge the catalytic combustor 70. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system and an operation method thereof.

  In recent years, a polymer electrolyte fuel cell (PEFC) that generates electricity by generating an electrochemical reaction by supplying hydrogen (fuel gas) to the anode and oxygen (oxidant gas) to the cathode, etc. The development of fuel cells is thriving. Fuel cells are being applied in a wide range, such as fuel cell vehicles that run on the power generated by them, and household power supplies, and their application range is expected to expand in the future.

In order to generate such a fuel cell satisfactorily, a suitable power generation temperature (70 to 80 ° C. in the case of PEFC) related to the catalyst and the like contained in the anode and the like so that the electrode reaction at the anode and cathode proceeds well. It is preferable to warm up. Therefore, a fuel cell system has been proposed in which hydrogen and air are catalytically combusted by a catalytic combustor, combustion heat is generated, and the fuel cell is warmed up using the combustion heat (see Patent Document 1).
JP 2003-243209 A

  However, when hydrogen and air are subjected to catalytic combustion, water vapor is generated, and this water vapor may adhere to the surface of the catalyst built in the catalytic combustor. In addition, when the catalytic combustor is connected to an offgas pipe through which offgas discharged from the fuel cell flows, there is a risk that water vapor generated by power generation may enter the catalytic combustor and adhere to the catalyst surface in the fuel cell. is there.

  In this way, when hydrogen and air are supplied to the catalytic combustor in order to warm up the fuel cell at the next system start-up with moisture remaining on the catalyst surface, the hydrogen and air and the catalyst are added to the catalyst combustor. The contact with the catalyst is hindered and it becomes difficult for the catalyst to burn. As a result, the combustion heat of catalytic combustion makes it difficult for the temperature of the catalyst to rise to its preferred activation temperature, and the time until the catalyst combustor reaches a temperature at which it can operate satisfactorily increases. Moreover, since it is difficult to perform catalytic combustion in this manner, the amount of unburned hydrogen discharged from the catalytic combustor increases.

  Accordingly, the present invention provides a fuel cell capable of suitably performing catalytic combustion of fuel gas and oxidant gas at the time of system startup to quickly increase the catalyst temperature and reducing discharge of unburned fuel gas from the catalytic combustor. It is an object to provide a system and an operation method thereof.

  As means for solving the above-mentioned problems, the present invention provides a fuel cell that generates power by supplying fuel gas and oxidant gas, oxidant gas supply means for supplying oxidant gas, and via the fuel cell. A heat exchange fluid circulation means for circulating the heat exchange fluid, catalytic combustion of the fuel gas and the oxidant gas, heating the circulating heat exchange fluid, and scavenging the catalyst combustor with scavenging gas A catalytic combustor scavenging means, wherein the fuel cell and the catalytic combustor are arranged in parallel with the oxidant gas supply means, and when it is determined to warm up the fuel cell at the time of system startup, A fuel cell system in which a catalytic combustor warms up the fuel cell via a heat exchange fluid, comprising: a warm-up completion determining unit that determines whether or not the fuel cell has been warmed-up; Completion size After it is determined by the means that the warm-up of the fuel cell is completed, the catalytic combustor scavenging means supplies scavenging gas to the catalytic combustor and scavenges the catalytic combustor. System.

Here, scavenging the catalytic combustor means pushing out moisture (water vapor, condensed water, etc.) remaining in the catalytic combustor to the outside of the catalytic combustor. And scavenging gas means the gas introduce | transduced into this in order to scavenge a catalyst combustor in this way.
In addition, the fuel cell and the catalytic combustor are arranged in parallel to the oxidant gas supply means that the oxidant gas discharged from one oxidant gas supply means branches and the fuel cell and the catalyst. It means that the fuel cell and the catalytic combustor are arranged so as to be supplied to the combustor.

  According to such a fuel cell system, after it is determined that the warm-up of the fuel cell is completed by the warm-up completion determination unit, the catalytic combustor scavenging unit converts the scavenging gas whose temperature has been increased by compression into the catalytic combustor. Since the gas is supplied and scavenging the catalyst combustor, moisture (water vapor, condensed water, etc.) remaining in the catalyst combustor can be discharged to the outside. This prevents the inside of the catalytic combustor from being frozen during the system stop.

Therefore, when the fuel gas and the oxidant gas are supplied to the catalytic combustor in order to warm up the fuel cell at the next system startup, the fuel gas and the oxidant gas are not blocked by moisture and are not blocked by the catalyst. Can touch. As a result, the fuel gas and the oxidant gas can be catalytically burned well under the catalyst, and as a result, the temperature of the catalyst rises rapidly and quickly reaches its preferred activation temperature. That is, the time until the catalytic combustor reaches its preferred operating temperature does not increase.
Further, since the fuel gas and the oxidant gas are favorably catalytically combusted in the catalytic combustor, unburned fuel gas discharged from the catalytic combustor can be reduced.

  The catalytic combustor scavenging means scavenges when the heat exchange fluid circulates through the catalytic combustor.

  According to such a fuel cell system, after the warm-up is completed, when the refrigerant heated by the self-heating of the fuel cell that generates electricity is circulated through the catalyst combustor, the catalytic combustor scavenging means is the catalyst. Scavenge the combustor. That is, the catalyst combustor is scavenged with scavenging gas from the catalyst combustor scavenging means while warming the catalyst combustor with warm refrigerant, so that scavenging of the catalyst combustor with scavenging gas, that is, drying of the inside thereof can be promoted. it can.

  A temperature detecting means for detecting the temperature of the heat exchange fluid discharged from the fuel cell; and a switching means for switching whether or not the refrigerant passes through the catalytic combustor based on the temperature of the heat exchange fluid; A fuel cell system comprising:

  According to such a fuel cell system, for example, when the temperature of the heat exchange fluid detected by the temperature detection means is equal to or higher than a predetermined temperature, the switching means is configured so that the refrigerant passes through the catalyst combustor, When the temperature of the exchange fluid is not equal to or higher than the predetermined temperature, the switching means is configured so that the refrigerant bypasses the catalyst combustor, so that the catalyst combustor is warmed by the heat exchange fluid of the predetermined temperature or higher and the catalyst combustor scavenging means is used. The catalytic combustor can be scavenged with this scavenging gas.

  The catalytic combustor scavenging means stops the supply of the scavenging gas to the catalytic combustor when the cumulative supply time of the scavenging gas to the catalytic combustor reaches a predetermined time. System.

According to such a fuel cell system, when the cumulative supply time of the scavenging gas to the catalytic combustor reaches the predetermined cumulative supply time, the supply of the scavenging gas to the catalytic combustor by the catalytic combustor scavenging means is stopped. That is, since the stop determination of the supply of the scavenging gas to the catalytic combustor is performed based on the cumulative supply time of the scavenging gas to the catalytic combustor, for example, the supply (scavenging) of the scavenging gas to the catalytic combustor is interrupted. However, the amount of the scavenging gas necessary for scavenging the catalyst combustor and associated with the predetermined integrated supply time can be supplied.
When the integrated supply time reaches the predetermined integrated supply time, the supply of scavenging gas to the catalytic combustor is stopped, so that the energy consumption of the catalytic combustor scavenging means and its operating noise can be suppressed.

  Further, the catalytic combustor scavenging means stops the supply of the scavenging gas to the catalytic combustor when the cumulative supply amount of the scavenging gas to the catalytic combustor reaches a predetermined supply amount. It is a battery system.

  According to such a fuel cell system, since the stop determination of the supply of the scavenging gas to the catalytic combustor is performed based on the integrated supply amount of the scavenging gas to the catalytic combustor, for example, the scavenging gas to the catalytic combustor Even if the supply (scavenging) is interrupted, a predetermined cumulative supply amount of scavenging gas necessary for scavenging of the catalytic combustor can be supplied. When the integrated supply amount reaches the predetermined integrated supply amount, the energy consumption of the catalytic combustor scavenging means can be suppressed by stopping the supply of the scavenging gas to the catalytic combustor.

  The catalytic combustor scavenging means is the oxidant gas supply means, the scavenging gas is an oxidant gas discharged from the oxidant gas supply means, and the oxidant gas supply means is the fuel cell. The fuel cell system is characterized in that the oxidant gas is supplied to the catalytic combustor so as not to run out of the oxidant gas in the fuel cell in accordance with the consumption amount of the oxidant gas.

  According to such a fuel cell system, the oxidant gas supply means, which is a catalyst combustor scavenging means, corresponding to the oxidant gas consumption in the fuel cell, so as not to run out of oxidant gas in the fuel cell, An oxidant gas is supplied as a scavenging gas to the catalytic combustor. That is, when the power generation requirement for the fuel cell is small and the supply amount of the oxidant gas to the fuel cell is sufficient, the oxidant gas supply means supplies the oxidant gas to the catalytic combustor. While ensuring the power generation performance (output power), the oxidant gas can be supplied to the catalytic combustor to scavenge the catalytic combustor.

  Further, as means for solving the above-mentioned problems, the present invention provides a fuel cell that generates power by being supplied with a fuel gas and an oxidant gas, an oxidant gas supply unit that supplies an oxidant gas, and the fuel cell. A heat exchange fluid circulation means for circulating the heat exchange fluid so as to pass through, a catalyst combustor for catalytically burning the fuel gas and the oxidant gas and heating the circulating heat exchange fluid, and the catalyst combustor by scavenging gas A catalyst combustor scavenging means for scavenging, wherein the fuel cell and the catalyst combustor are arranged in parallel with the oxidant gas supply means, and it is determined that the fuel cell is warmed up when the system is started An operation method of a fuel cell system in which the catalyst combustor warms up the fuel cell via a heat exchange fluid, and the catalyst combustor scavenging means is determined after the warm-up of the fuel cell is determined to be completed. The scavenging gas is supplied to the al the catalytic combustor, a method of operating a fuel cell system, characterized in that scavenging the catalytic combustor.

  According to such an operation method of the fuel cell system, after it is determined that the warm-up of the fuel cell is completed, the scavenging gas that has become hot due to compression is supplied from the catalytic combustor scavenging means to the catalytic combustor, Since the catalytic combustor is scavenged, moisture (water vapor, condensed water, etc.) remaining in the catalytic combustor can be discharged to the outside. This prevents the inside of the catalytic combustor from being frozen during the system stop.

Therefore, when the fuel gas and the oxidant gas are supplied to the catalytic combustor in order to warm up the fuel cell at the next system startup, the fuel gas and the oxidant gas are not blocked by moisture and are not blocked by the catalyst. Can touch. As a result, the fuel gas and the oxidant gas can be catalytically burned well under the catalyst, and as a result, the temperature of the catalyst rises rapidly and quickly reaches its preferred activation temperature. That is, the time until the catalytic combustor reaches its preferred operating temperature does not increase.
Further, since the fuel gas and the oxidant gas are favorably catalytically combusted in the catalytic combustor, unburned fuel gas discharged from the catalytic combustor can be reduced.

  According to the present invention, when the system is started, the fuel gas and the oxidant gas are preferably catalytically combusted to quickly increase the catalyst temperature and to reduce the discharge of unburned fuel gas from the catalytic combustor. A system and its operating method can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

≪Configuration of fuel cell system≫
A fuel cell system 1 according to this embodiment shown in FIG. 1 is mounted on a fuel cell vehicle (moving body) (not shown). The fuel cell system 1 includes a fuel cell stack 10, an anode system that supplies and discharges hydrogen (fuel gas) to and from the anode of the fuel cell stack 10, and air containing oxygen to the cathode of the fuel cell stack 10 (oxidant) A cathode system that supplies and discharges gas), a power consumption system that consumes power generated by the fuel cell stack 10, and a refrigerant circulation system that circulates refrigerant (heat exchange fluid) through the fuel cell stack (heat exchange fluid) (Circulation means), a refrigerant heating system for heating the circulating refrigerant, IG81 (ignition), and an ECU 90 (Electronic Control Unit) for electronically controlling them.

<Fuel cell stack>
The fuel cell stack 10 is a stack formed by stacking a plurality of (eg, 200 to 400) solid polymer type single cells, and the plurality of single cells are connected in series. The single cell includes an MEA (Membrane Electrode Assembly) and two conductive separators sandwiching the MEA. The MEA includes an electrolyte membrane (solid polymer membrane) made of a monovalent cation exchange membrane or the like, and an anode and a cathode sandwiching the electrolyte membrane.

The anode and cathode are mainly composed of a conductive porous material such as carbon paper, and contain a catalyst (Pt, Ru, etc.) for causing an electrode reaction in the anode and cathode.
Each separator is formed with a groove for supplying hydrogen or air to the entire surface of each MEA, and through holes for supplying and discharging hydrogen or air to all single cells. It functions as a channel 11 (fuel gas channel) and a cathode channel 12 (oxidant gas channel). Then, when hydrogen is supplied to each anode via the anode flow path 11 and air is supplied to each cathode via the cathode flow path 12, an electrode reaction occurs, and a potential difference (OCV Open Circuit Voltage) is generated in each single cell. Open circuit voltage). Next, when the OCV is equal to or higher than the predetermined OCV, there is a power generation request, the contactor 43 described later is turned on, the VCU 42 is controlled, and the current is taken out, so that the fuel cell stack 10 generates power.

  In the present embodiment, the fuel cell stack 10 and the catalytic combustor 70 are arranged in parallel to the compressor 31 (oxidant gas supply means). The air from the compressor 31 is appropriately distributed to the fuel cell stack 10 and the catalytic combustor 70 by appropriately opening and closing a back pressure valve 32 and an air introduction valve 63 described later.

<Anode system>
The anode system includes a hydrogen tank 21, a shutoff valve 22, an ejector 23, and a purge valve 24 (discharge valve).
The hydrogen tank 21 is connected to the inlet of the anode channel 11 through a pipe 21a, a shutoff valve 22, a pipe 22a, an ejector 23, and a pipe 23a. When the shutoff valve 22 is opened by a command from the ECU 90, hydrogen is supplied from the hydrogen tank 21 to the anode flow path 11 via the shutoff valve 22 and the like.

  The outlet of the anode channel 11 is connected to a diluter 33 described later via a pipe 24a, a purge valve 24, and a pipe 24b. The middle of the pipe 24a is connected to the ejector 23 via the pipe 24c.

  The purge valve 24 is an on-off valve controlled by the ECU 90 and is set to be closed during power generation of the fuel cell stack 10. Thereby, the anode off gas containing unreacted hydrogen discharged from the anode channel 11 is returned to the ejector 23 through the pipe 24c. The returned hydrogen is supplied again to the anode channel 11 so that the hydrogen circulates. That is, the fuel cell system 1 includes a hydrogen circulation system that circulates hydrogen so that hydrogen is efficiently used.

  On the other hand, when the impurities (water vapor, nitrogen, etc.) accompanying the circulating hydrogen increase and the output of the fuel cell stack 10 and / or single cell decreases, the purge valve 24 is opened and the anode off-gas is discharged to discharge the impurities. Is supplied to the diluter 33.

<Cathode system>
The cathode system includes a compressor 31 (oxidant gas supply means, catalytic combustor scavenging means), a back pressure valve 32, a diluter 33 (dilution device), a silencer 34 (silencer), and a hydrogen sensor 35 (fuel gas concentration). Detection means).
The compressor 31 is connected to the inlet of the cathode flow path 12 via a pipe 31a. When the compressor 31 is operated according to a command from the ECU 90, it takes in oxygen-containing air and supplies it to the cathode flow path 12. Further, the pipe 31a is provided with a humidifier (not shown) so that the air supplied to the cathode channel 12 is appropriately humidified.

  Further, the compressor 31 shares a power source (not shown) such as an electric motor with a pump 53 described later, that is, the compressor 31 and the impeller of the pump 53 are fixed around the drive shaft of the power source, respectively. The compressor 31 and the pump 53 are designed to be synchronized. Since the power source is shared in this way, the system configuration is simplified.

  The outlet of the cathode channel 12 is connected to the diluter 33 via a pipe 32 a, a back pressure valve 32, and a pipe 32 b, and the cathode off gas discharged from the cathode of the fuel cell stack 10 is supplied to the diluter 33. It is like that. That is, the back pressure valve 32 is disposed on the downstream side of the fuel cell stack 10 and is constituted by, for example, a butterfly valve, and its opening degree can be freely changed. Then, the opening degree of the back pressure valve 32 is controlled by the ECU 90, whereby the pressure and flow rate of air supplied from the compressor 31 to the cathode flow path 12 (cathode) of the fuel cell stack 10 are controlled. Yes.

  The diluter 33 mixes the anode off-gas introduced from the anode system by opening the purge valve 24 and the cathode off-gas (oxidant gas, dilution gas) discharged from the cathode flow path 12 into the anode off-gas. This is a device for diluting hydrogen, and has a dilution space for mixing these gases and diluting hydrogen. The gas diluted by the diluter 33 is discharged to the outside (outside) through the pipe 33a, the silencer 34, and the pipe 34a. In addition, the silencer 34 reduces the operating sound of the compressor 31 which transmits in the gas which flows through a cathode system.

The hydrogen sensor 35 is a sensor that detects the hydrogen concentration, and is disposed on the pipe 32b and downstream of the connection point between the pipe 33a and the pipe 70c through which exhaust gas discharged from the catalytic combustor 70 described later flows. Has been. That is, the hydrogen sensor 35 is disposed on the downstream side of the catalytic combustor 70.
The hydrogen sensor 35 detects the hydrogen concentration C11 in the gas flowing through the pipe 33a. The hydrogen sensor 35 is connected to the ECU 90, and the ECU 90 detects the hydrogen concentration C11.

<Power consumption system>
The power consumption system is a system that consumes the power generated by the fuel cell stack 10 and includes a travel motor 41 that is a power source of the fuel cell vehicle, a VCU 42 (Voltage Control Unit), and a contactor 43. The VCU 42 is a device that controls the output power (current, voltage) of the fuel cell stack 10, and includes a DC / DC chopper and the like. The contactor 43 is a switch for turning on / off the electrical connection between the fuel cell stack 10 and the VCU 42 and the traveling motor 41. The travel motor 41 is connected to the output terminal of the fuel cell stack 10 through a PDU (Power Drive Unit, not shown) that generates a three-phase alternating current, a VCU 42, and a contactor 43 in this order.

  When the ECU 90 controls the VCU 42 in response to a power generation request from the accelerator pedal 82 or the like with the contactor 43 turned on, current is taken out from the fuel cell stack 10, the fuel cell stack 10 generates power, and the traveling motor 41 is It is designed to rotate. On the other hand, when the contactor 43 is OFF, no current is taken out from the fuel cell stack 10, so that the fuel cell stack 10 does not generate power.

In addition, the power consumption system includes a power storage device, a DC / DC converter, and the like (both not shown). The power storage device accumulates surplus power generated by the fuel cell stack 10 and regenerative power from the traveling motor 41, or assists the fuel cell stack 10 by discharging the charged power when the power generated by the fuel cell stack 10 is low. It is. The DC / DC converter appropriately boosts and lowers the electric power charged / discharged in the power storage device.
Further, the compressor 31, the pump 53, the shutoff valve 22, the purge valve 24, and the like are also included in the power consumption system, and operate with the power storage device and / or the fuel cell stack 10 as a power source. For this reason, even when there is no power generation request from the accelerator pedal 82 or the like, when it is necessary to operate an auxiliary machine such as the compressor 31, the ECU 90 generates power in the fuel cell stack 10 accordingly.

<Refrigerant circulation system>
The refrigerant circulation system circulates a refrigerant such as ethylene glycol so as to pass through the refrigerant flow path 13 of the fuel cell stack 10, and includes a radiator 51, a thermostat 52, a pump 53, and a three-way valve 54 (switching). Means) and a temperature sensor 55 (temperature detection means).

  The outlet of the refrigerant flow path 13 is connected to the inlet of the refrigerant flow path 13 via a pipe 52a, a thermostat 52, a pipe 52b, a pump 53, a pipe 53a, a three-way valve 54, and a pipe 54a. When the pump 53 operates in accordance with a command from the ECU 90, the refrigerant circulates.

The three-way valve 54 is controlled by the ECU 90 and can communicate the pipe 53a with the pipe 54a or a pipe 70a described later, and can switch whether or not to pass the circulating refrigerant through the catalyst combustor 70. . When the fuel cell stack 10 is warmed up by the catalytic combustor 70 at the time of starting the system, the three-way valve 54 is controlled so that the refrigerant passes through the pipes 53a and 70a and the refrigerant goes to the catalytic combustor 70. .
However, it is not limited to the three-way valve 54 as long as it is possible to switch between circulating and bypassing the catalyst combustor 70. For example, an on-off valve may be provided in each of the pipes 54a and 70a to open and close them appropriately. Good.

  The middle of the pipe 52a is connected to the thermostat 52 through the pipe 51a, the radiator 51, and the pipe 51b. The thermostat 52 is configured to close when the temperature of the refrigerant is low, and to connect the pipe 52a and the pipe 52b. On the other hand, when the temperature of the refrigerant increases, the thermostat 52 opens, the pipe 51b and the pipe 52b communicate with each other, and the high-temperature refrigerant is cooled by the radiator 51.

The temperature sensor 55 is a sensor that detects the temperature Tw of the refrigerant immediately after being discharged from the refrigerant flow path 13, and is provided in the pipe 52a.
In the present embodiment, it is assumed that the temperature Tw of the refrigerant is equal to the temperature of the fuel cell stack 10, and the temperature Tw indicates the temperature of the refrigerant and the fuel cell stack 10. The temperature sensor 55 is connected to the ECU 90, and the ECU 90 detects the temperature Tw of the refrigerant and the fuel cell stack 10 based on a detection signal from the temperature sensor 55.

<Refrigerant heating system>
The refrigerant heating system is a system for heating circulating refrigerant, and includes a hydrogen introduction valve 61, a hydrogen supply means 62 (for example, an injector), an air introduction valve 63, a mixer 64 (mixer), and a catalytic combustor 70. And.

  The upstream side of the air introduction valve 63 is connected to the pipe 31a via the pipe 63a, and the downstream side of the air introduction valve 63 is connected to the mixer 64 via the pipe 63b. During operation of the compressor 31, when the air introduction valve 63 is opened by the ECU 90, oxygen-containing air (oxidant gas, scavenging gas) is introduced into the mixer 64. That is, when scavenging the catalyst combustor 70, the air introduction valve 63 is opened, and air (scavenging gas, oxidant gas) is introduced from the compressor 31 (catalyst combustor scavenging means) to the catalyst combustor 70. ing.

  The upstream side of the hydrogen introduction valve 61 is connected to the pipe 21a via the pipe 61a, and the downstream side of the hydrogen introduction valve 61 is connected to the hydrogen supply means 62 via the pipe 61b. It is provided in the middle of 63b. Then, when the hydrogen introduction valve 61 is opened by the command from the ECU 90 and the hydrogen supply means 62 is appropriately controlled, hydrogen is discharged (supplied) from the hydrogen supply means 62 into the pipe 63b and together with the air passing through the pipe 63b. The mixer 64 is introduced.

  The mixer 64 is a device that mixes hydrogen and air introduced into the mixer 64 to generate a fuel mixed gas, and has a mixing space therein. Therefore, the mixer 64 preferably includes a diffusing means such as a rib for diffusing hydrogen or the like in order to properly mix hydrogen and air. The fuel mixed gas is supplied to the catalyst unit 71 of the catalytic combustor 70 via the pipe 64a.

The catalytic combustor 70 is a device that combusts a fuel mixed gas under a catalyst and heats the refrigerant with the combustion heat, and includes a catalyst unit 71 and a heat exchange unit 75.
The catalyst unit 71 includes a catalyst unit main body 72, a cylindrical water jacket 73 surrounding the catalyst unit main body 72, and a temperature sensor 74. The catalyst unit main body 72 includes a honeycomb body formed of cordierite or the like and having a plurality of pores serving as fuel gas passages, and a catalyst such as Pt or Ru supported on a wall surface surrounding the pores. Yes. When the fuel mixed gas is supplied to the catalyst unit main body 72, hydrogen and oxygen undergo a combustion reaction under the catalyst to generate high-temperature exhaust gas with combustion heat. This high-temperature exhaust gas is supplied to the heat exchange unit 75.

  The temperature sensor 74 is a sensor that detects the temperature of the exhaust gas from the catalyst unit body 72 toward the heat exchange unit 75 as the catalyst temperature (catalyst temperature Ts) of the catalyst unit body 72. The temperature sensor 74 is connected to the ECU 90, and the ECU 90 detects the catalyst temperature Ts based on a detection signal from the temperature sensor 74.

  The heat exchanging unit 75 is a part that heats the refrigerant by exchanging heat between the high-temperature exhaust gas and the refrigerant flowing through the high-temperature exhaust gas. The refrigerant is introduced from the three-way valve 54 into the heat exchanging portion 75 through the pipe 70a, heated by the high-temperature exhaust gas, passes through the water jacket 73 disposed outside the catalyst portion main body 72, and then is passed through the pipe 70b. Is sent to the pipe 54a.

  Further, the exhaust gas after the heat exchange is introduced into the pipe 33a through the pipe 70c (exhaust gas pipe). Therefore, the unburned hydrogen concentration C11 in the gas discharged to the outside is detected by the hydrogen sensor 35.

<Other equipment>
The IG 61 is a start switch for the fuel cell vehicle and the fuel cell system 1 and is provided around the driver's seat. Further, the IG 61 is connected to the ECU 90, and the ECU 90 detects an ON / OFF signal of the IG 61.

  An accelerator pedal 82 (Accelerator Pedal: AP) is a pedal that the driver steps on in response to a travel request, and is disposed at the foot of the driver's seat. Then, the accelerator pedal 82 sends a signal based on the degree of depression of the accelerator pedal 82 to the ECU 90. The ECU 90 detects the amount of depression of the accelerator pedal 82, and when the accelerator pedal 82 is depressed, And, it has come to recognize that there is a power generation request from the driver.

<ECU>
The ECU 90 is a control device that electronically controls the fuel cell system 1 and includes a CPU, a ROM, a RAM, various interfaces, an electronic circuit, and the like, and executes various processes in accordance with programs stored therein. It is supposed to be.

  The ECU 90 appropriately controls the shutoff valve 22, the purge valve 24, the compressor 31, and the back pressure valve 32 to supply hydrogen and air to the fuel cell stack 10, and controls the contactor 43 and the VCU 42 to thereby control the fuel cell stack. 10 has a function of generating electricity.

  The ECU 90 (warming-up necessity determining means) uses the catalytic combustor 70 based on the temperature Tw of the fuel cell stack 10 and the warming-up required temperature T1 (for example, 0 ° C.) when the fuel cell system 1 is started. Thus, a function for determining whether or not the fuel cell stack 10 needs to be warmed up is provided. The warm-up required temperature T1 is a temperature at which the inside of the fuel cell stack 10 is predicted to be frozen, is related to the material of the MEA, etc., and is obtained by a preliminary test.

  When it is determined that the fuel cell stack 10 is to be warmed up, the ECU 90 controls the compressor 31, the hydrogen introduction valve 61, the hydrogen supply means 62, the air introduction valve 63, the pump 53, etc. The fuel cell stack 10 has a function of warming up the fuel cell stack 10 through the circulating refrigerant by introducing air and generating fuel heat by catalytic combustion.

Further, after starting the warm-up of the fuel cell stack 10, the ECU 90 determines whether or not the temperature Tw of the fuel cell stack 10 is equal to or higher than a temperature at which self-power generation is possible (self-power generation possible temperature T2, for example, −10 ° C.). It has a function to judge.
Furthermore, the ECU 90 (warm-up completion determination means) starts the power generation of the fuel cell stack 10 and then rises in temperature due to self-heating, and is at or above the temperature at which the warm-up is completed (warm-up completion temperature T3, for example, 30 ° C.). A function for determining whether or not there is provided.
The self-power generation possible temperature T2 and the warm-up completion temperature T3 are related to the material of the MEA and the like and are obtained by a preliminary test.

In addition, the ECU 90 determines that the temperature Tw of the refrigerant immediately after being discharged from the fuel cell stack 10 after the completion of the warm-up of the fuel cell stack 10 is the temperature at which the refrigerant is allowed to pass through the catalytic combustor 70 (refrigerant). A function is provided for determining whether or not the temperature is Vpassable temperature T4, a predetermined temperature (for example, 70 ° C.) or higher. Based on the determination result, the ECU 90 has a function of controlling the three-way valve 54 (switching means) to switch between the bypass and bypass of the refrigerant catalytic combustor 70.
The refrigerant-passable temperature T4 is a temperature at which scavenging of the catalyst combustor 70 is predicted to be promoted by a warm refrigerant if a refrigerant having a temperature equal to or higher than this temperature is supplied to the catalyst combustor 70, and is obtained by a preliminary test or the like. .

Further, the ECU 90 includes a map in which the power generation request amount from the accelerator pedal 82 and the like, the power generation request amount and the air flow rate to be supplied to the fuel cell stack 10 (the rotation speed of the compressor 31) are associated in advance, and the current air flow rate. Based on (the current rotation speed of the compressor 31) and a function of determining whether or not there is a margin in the air flow rate (FC air flow rate) supplied from the compressor 31 to the fuel cell stack 10.
That is, the ECU 90 determines whether there is a margin based on the air flow rate based on the air amount (consumption amount) to be consumed by the fuel cell stack 10 based on the power generation request and the current air flow rate. It has. The ECU 90 has a function of opening and closing the air introduction valve 63 and scavenging the catalytic combustor 70 based on the determination result.

  Furthermore, the ECU 90 has a function of determining whether or not scavenging of the catalytic combustor 70 has been completed by the air from the compressor 31.

≪Operation and operation method of fuel cell system≫
Next, the operation and operation method of the fuel cell system 1 will be described together with the flow of a program (flow chart) set in the ECU 90.
When the IG 81 is turned on, the process shown in the flowchart of FIG. 2 starts. In addition, before the IG 81 is turned on (initial state), the compressor 31 and the pump 53 are stopped. The shut-off valve 22, the purge valve 24, the back pressure valve 32, the hydrogen introduction valve 61, and the air introduction valve 63 are closed, and the contactor 43 is turned off. The three-way valve 54 is in a position where the pipe 53a and the pipe 54a communicate with each other, that is, a position where the refrigerant bypasses the catalyst combustor 70.

<Use judgment of catalyst combustor>
In step S101, the ECU 90 determines whether or not it is necessary to use the catalytic combustor 70 when starting the fuel cell system 1 based on the temperature Tw of the fuel cell stack 10 and the warm-up required temperature T1, that is, the catalyst. It is determined whether the fuel cell stack 10 needs to be warmed up using the combustor 70.

Specifically, when the temperature Tw of the fuel cell stack 10 is lower than the warming-up required temperature T1, the inside of the fuel cell stack 10 may be frozen, so it is determined that the catalytic combustor 70 needs to be used. However, the process of the ECU 90 proceeds to step S102.
On the other hand, when the temperature Tw of the fuel cell stack 10 is not lower than the warming-up required temperature T1, it is determined that it is not necessary to use the catalytic combustor 70 (S101, No), and the processing of the ECU 90 proceeds to step S114.

In step S102, the ECU 90 starts operation of the catalytic combustor 70 and warms up the fuel cell stack 10.
Specifically, the ECU 90 opens the air introduction valve 63 and operates the compressor 31 and the pump 53. In parallel with this, the ECU 90 opens the hydrogen introduction valve 61, appropriately controls the hydrogen supply means 62, and discharges hydrogen into the pipe 63b.
As a result, hydrogen and air are sent to the mixer 64 and are suitably mixed by the mixer 64 to generate a fuel mixed gas. This fuel mixed gas is supplied to the catalyst section main body 72 of the catalytic combustor 70.
Further, the ECU 90 controls the three-way valve 54 to cause the pipe 53a and the pipe 70a to communicate with each other. Thereby, the refrigerant circulating by the operation of the pump 53 passes through the catalytic combustor 70.

Then, in the catalyst unit main body 72, hydrogen and oxygen in the fuel mixed gas undergo catalytic combustion to generate combustion heat, and high-temperature exhaust gas having this combustion heat is generated. And the catalyst temperature Ts of the catalyst part main body 72 begins to rise with this combustion heat.
The exhaust gas exchanges heat with the refrigerant in the heat exchanging unit 75, heats the refrigerant, and then is discharged to the outside through the pipes 70c and 33a and the silencer 34. On the other hand, the heated refrigerant passes through the water jacket 73 and is then supplied to the refrigerant flow path 13 via the pipes 70b and 54a. As a result, the temperature Tw of the fuel cell stack 10 starts to rise. The exhaust gas discharged from the catalyst combustor 70 includes unburned hydrogen, and the hydrogen concentration C11 is detected by the hydrogen sensor 35.

In step S103, the ECU 90 determines whether or not the temperature Tw of the fuel cell stack 10 is equal to or higher than a self-power generation possible temperature T2 (for example, −10 ° C.).
When it is determined that the temperature Tw of the fuel cell stack 10 is equal to or higher than the self-power generation possible temperature T2 (S103 / Yes), the processing of the ECU 90 proceeds to step S104. On the other hand, when it is determined that the temperature Tw of the fuel cell stack 10 is not equal to or higher than the self-power generation possible temperature T2 (S103, No), the processing of the ECU 90 repeats the determination of step S103.

In step S104, the ECU 90 stops the operation of the catalytic combustor 70 and stops warming up of the fuel cell stack 10 by the catalytic combustor 70.
Specifically, the ECU 90 closes the hydrogen introduction valve 61 and the air introduction valve 63. However, after the hydrogen introduction valve 61 is closed, the air introduction valve 63 is opened for a predetermined time, and air is sent from the compressor 31 to the catalytic combustor 70, and the hydrogen remaining in the catalytic combustor 70 by this air. Is preferably discharged.
Further, the ECU 90 controls the three-way valve 54 to a position where the pipe 53a and the pipe 54a communicate with each other. Thereby, the circulating refrigerant bypasses the catalytic combustor 70.

In step S105, the ECU 90 replaces the gas in the fuel cell stack 10.
Specifically, after opening the shut-off valve 22, the ECU 90 appropriately opens the purge valve 24 to replace the inside of the anode flow path 11 with hydrogen. In parallel with this, the ECU 90 opens the back pressure valve 32 and replaces the inside of the cathode flow path 12 with air. Such replacement with hydrogen and air is continued until the OCV of the fuel cell stack 10 detected via a voltage sensor (not shown) is increased to a predetermined OCV that can permit power generation.

In step S106, the ECU 90 starts power generation of the fuel cell stack 10.
Specifically, the ECU 90 turns on the contactor 43, controls the VCU 42 in response to a power generation request from an accelerator pedal or an in-vehicle air conditioner, extracts current from the fuel cell stack 10, and generates power. When power generation of the fuel cell stack 10 is started in this way, the temperature Tw of the fuel cell stack 10 and the refrigerant starts to rise due to self-heating due to power generation.

In step S107, the ECU 90 determines whether or not the temperature Tw of the fuel cell stack 10 is equal to or higher than the warm-up completion temperature T3 (for example, 30 ° C.).
When it is determined that the temperature Tw of the fuel cell stack 10 is equal to or higher than the warm-up completion temperature T3 (S107 / Yes), the processing of the ECU 90 proceeds to step S108. On the other hand, when it is determined that the temperature Tw of the fuel cell stack 10 is not equal to or higher than the warm-up completion temperature T3 (No at S107), the process of the ECU 90 repeats the determination at Step S107.

In step S108, the ECU 90 determines whether or not the refrigerant temperature Tw is equal to or higher than the refrigerant passing temperature T4 (for example, 70 ° C.).
When it is determined that the refrigerant temperature Tw is equal to or higher than the refrigerant passing temperature T4 (Yes in S108), the process of the ECU 90 proceeds to step S109. On the other hand, when it is determined that the refrigerant temperature Tw is not equal to or higher than the refrigerant passing temperature T4 (S108, No), the process of the ECU 90 proceeds to step S115.

  In step S109, the ECU 90 controls the three-way valve 54 so that the circulating refrigerant passes through the catalytic combustor 70, thereby causing the pipe 53a and the pipe 70a to communicate with each other.

In step S110, the ECU 90 supplies the fuel cell stack 10 with a map in which the current power generation request amount from the accelerator pedal 82 and the like, the power generation request amount and the amount of air to be supplied to the fuel cell stack 10 are associated in advance. It is determined whether or not there is a margin in the air flow rate to the fuel cell stack 10 based on the current air flow rate.
That is, for example, when the fuel cell vehicle is idlingly stopped (when idling is stopped), or when regenerative power is generated by the traveling motor 41 (when regenerating), the purge valve is not opened, or If the purged hydrogen is not diluted with the gas (cathode off-gas) from the compressor 31 (ie, when the purge hydrogen is not diluted), it is determined that there is a margin. The air flow rate to the fuel cell stack 10 is estimated or detected based on, for example, the rotational speed of the compressor 31 or a flow rate sensor (not shown) provided upstream of the pipe 31a or the compressor 31.

  If it is determined that there is a margin in the air flow rate to the fuel cell stack 10 (S110 / Yes), the processing of the ECU 90 proceeds to step S111. On the other hand, when it is determined that the air flow rate to the fuel cell stack 10 is not sufficient (S110 · No), the processing of the ECU 90 proceeds to step S116.

In step S111, the ECU 90 opens the air introduction valve 63 or continues the opened state. As a result, high-temperature compressed air from the compressor 31 (catalyst combustor scavenging means) is supplied to the catalyst combustor 70. If it does so, the water | moisture content (water vapor | steam, dew condensation water, etc.) in the catalyst part main body 72 will be extruded by high temperature air, and scavenging of the catalyst combustor 70 will advance.
At this time, since a warm refrigerant having a temperature that can be passed through the refrigerant T4 or higher is flowing through the water jacket 73, the high-temperature refrigerant also warms the catalyst unit main body 72 and the air flowing therethrough. Scavenging progresses.

In step S112, the ECU 90 determines whether scavenging of the catalytic combustor 70 has been completed.
As a scavenging completion determination method, when the integrated time (integrated scavenging time) of the time when the air from the compressor 31 flows through the catalytic combustor 70 is equal to or longer than the scavenging completion time, it can be determined that scavenging has been completed. The integrated scavenging time is the opening time of the air introduction valve 63 and is obtained by using a clock built in the ECU 90. Further, the scavenging completion time is an accumulated time when scavenging in the catalyst combustor 70 is completed, and is obtained by a preliminary test or the like.

  As a scavenging completion determination method, when the integrated amount of air flowing through the catalytic combustor 70 (integrated scavenging air amount) is equal to or greater than the scavenging completion air amount, it can be determined that scavenging has been completed. The integrated scavenging air amount is obtained based on, for example, the discharge amount (L / min) of the compressor 31, the distribution ratio of air toward the pipe 63a, and the open time of the air introduction valve 63. In addition, it is obtained based on the air flow rate by a flow rate sensor (not shown) provided in the pipe 63a and the like and the open time of the air introduction valve 63. The scavenging completion air amount is an integrated amount of air that is assumed to be scavenging in the catalytic combustor 70, and is obtained by a preliminary test or the like.

If it is determined that scavenging has been completed (S112 / Yes), the processing of the ECU 90 proceeds to step S113. Here, an on-off valve (not shown) is provided in the pipe 70c, and in order to prevent the humid air from flowing into the catalytic combustor 70 from the outside after it is determined that scavenging has been completed in this way, the on-off valve is provided. It is good also as a structure which closes.
On the other hand, when it is determined that scavenging has not been completed (No at S112), the process of the ECU 90 proceeds to step S108.

  In step S113, since the scavenging of the catalytic combustor 70 has been completed, the ECU 90 controls the three-way valve 54 so that the pipe 53a and the pipe 54a communicate with each other. Thereby, the refrigerant bypasses the catalytic combustor 70. Further, the ECU 90 closes the air introduction valve 63.

  In step S114, the ECU 90 causes the fuel cell system 1 to operate with normal power generation control. That is, the ECU 90 controls the VCU 42 in response to a power generation request from the accelerator pedal 82 or the like, and causes the fuel cell stack 10 to generate power.

Next, step S115 that proceeds when step S108 is No will be described.
In step S115, the ECU 90 controls the three-way valve 54 so that the circulating refrigerant bypasses the catalytic combustor 70, thereby causing the pipe 53a and the pipe 54a to communicate with each other. Thereby, since the low-temperature refrigerant is not supplied to the catalytic combustor 70, the water vapor hardly forms condensation in the catalytic combustor 70.

Next, step S116 that is performed after step S115 and when step S110 is No will be described.
In step S116, the ECU 90 closes the air introduction valve 63 or continues the closed state. As a result, air is not supplied to the catalytic combustor 70.
Thereafter, the processing of the ECU 90 proceeds to step S108.

≪Effect of fuel cell system≫
According to such a fuel cell system 1, the following effects can be obtained.
After the warm-up of the fuel cell stack 10 is completed (S107 / Yes), the catalytic combustor 70 can be scavenged using the high-temperature compressed air and the high-temperature refrigerant, and the moisture in the catalyst unit main body 72 can be removed. Can be reduced. Thus, when hydrogen and air are supplied to the catalytic combustor 70 in order to warm up the fuel cell stack 10 at the next system startup, the hydrogen and air will contact the catalyst without being inhibited by moisture. Can do.

As a result, hydrogen and air can be catalytically burned well under the catalyst, and the catalyst temperature Ts rises rapidly due to the heat of combustion. As a result, the catalyst temperature Ts quickly reaches the preparation completion temperature T5 (preferred catalyst activation temperature) at which stable catalytic combustion is possible (see FIG. 3A).
Since the catalyst temperature Ts quickly reaches the preparation completion temperature T5 in this way, hydrogen and air can be favorably catalytically burned under the catalyst, and unburned hydrogen discharged from the catalyst combustor 70 is reduced. can do. Therefore, it is possible to prevent the hydrogen concentration C11 in the gas discharged outside the vehicle from exceeding the upper limit hydrogen concentration C2 that can be discharged outside (see FIG. 3B).

  Further, scavenging of the catalytic combustor 70 with high-temperature compressed air is performed when a refrigerant having a temperature Tw of the refrigerant that is higher than the refrigerant-passable temperature T4 that can promote scavenging passes through the catalytic combustor 70. Drying in the combustor 70 can be promoted.

  Further, since the scavenging of the catalyst combustor 70 is executed only when there is a margin in the flow rate of air supplied to the fuel cell stack 10, it is possible to prevent the fuel cell stack 10 from running out of air. That is, the fuel cell stack 10 is prevented from being unable to generate power in response to a power generation request from the accelerator pedal 82 or the like.

  Furthermore, whether or not scavenging of the catalytic combustor 70 has been completed can be appropriately determined based on the cumulative supply time or integrated supply amount of air to the catalytic combustor 70. Thereby, the air from the compressor 31 can be used effectively.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to the said embodiment, For example, it can change as follows in the range which does not deviate from the meaning of this invention.

  In the above embodiment, the case where the temperature sensor that detects the temperature of the fuel cell stack 10 is the temperature sensor 55 that detects the temperature Tw of the refrigerant is exemplified. These temperature sensors for detection may be provided in the pipes 24 a and 32 a through which the anode off-gas and cathode off-gas flow, or directly in the fuel cell stack 10. A plurality of temperature sensors may be provided to prevent erroneous detection.

In the above-described embodiment, the compressor 31 is an oxidant gas supply unit that supplies air (oxidant gas) to the cathode flow path 12 and supplies air as a scavenging gas to the catalytic combustor 70 during the scavenging. Although the structure which is a catalyst combustor scavenging means is illustrated, the compressor 31 does not need to serve as both means. That is, it is good also as a structure provided with the compressor for scavenging of the catalyst combustor 70 separately from the compressor 31. FIG.
In such a configuration, the catalyst combustor 70 can be scavenged by operating the separately provided compressor regardless of whether or not the flow rate of the air supplied to the fuel cell stack 10 has a margin. .

  In the above-described embodiment, the case where the fuel cell system 1 includes the hydrogen circulation system configured by the pipe 24c and the like is illustrated, but the present invention may be applied to a fuel cell system that does not include the hydrogen circulation system. Further, the present invention may be applied to the fuel cell system 1 that does not include the diluter 33.

  In the above-described embodiment, the case where the fuel cell system 1 is mounted on a fuel cell vehicle has been illustrated. However, for example, a fuel cell system mounted on a motorcycle, a train, or a ship may be used. Further, the present invention may be applied to a stationary fuel cell system for home use or a fuel cell system incorporated in a hot water supply system.

It is a block diagram of the fuel cell system which concerns on this embodiment. It is a flowchart which shows operation | movement of the fuel cell system which concerns on this embodiment. (A), (b) is a graph which shows the effect of the fuel cell system concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 10 Fuel cell stack 11 Anode flow path (fuel gas flow path)
12 Cathode channel (oxidant gas channel)
13 Refrigerant flow path 31 Compressor (oxidant gas supply means, catalytic combustor scavenging means)
53 Pump (heat exchange fluid circulation means)
54 Three-way valve (switching means)
55 Temperature sensor (temperature detection means)
63 Air Introducing Valve 70 Catalytic Combustor 71 Catalyst Part 72 Catalyst Part Main Body 73 Water Jacket 74 Temperature Sensor (Catalyst Temperature Detection Means)
75 heat exchanger 90 ECU (warm-up completion judging means)
T1 Warm-up required temperature T2 Self-power generation possible temperature T3 Warm-up completion temperature T4 Refrigerable temperature Ts Catalyst temperature Tw Fuel cell stack / refrigerant temperature

Claims (7)

A fuel cell that generates electricity by being supplied with fuel gas and oxidant gas;
Oxidant gas supply means for supplying oxidant gas;
Heat exchange fluid circulation means for circulating the heat exchange fluid so as to pass through the fuel cell;
A catalytic combustor for catalytically burning a fuel gas and an oxidant gas and heating a circulating heat exchange fluid;
Catalytic combustor scavenging means for scavenging the catalytic combustor with scavenging gas;
With
The fuel cell and the catalytic combustor are arranged in parallel with the oxidant gas supply means,
A fuel cell system in which the catalytic combustor warms up the fuel cell via a heat exchange fluid when it is determined to warm up the fuel cell at the time of system startup;
Comprising a warm-up completion determination means for determining whether or not the fuel cell has been warmed-up,
After the warm-up completion determining means determines that the fuel cell has been warmed up, the catalytic combustor scavenging means supplies scavenging gas to the catalytic combustor to scavenge the catalytic combustor. A fuel cell system. The fuel cell system according to claim 1, wherein the catalytic combustor scavenging means scavenges when the heat exchange fluid circulates through the catalytic combustor. Temperature detecting means for detecting the temperature of the heat exchange fluid discharged from the fuel cell;
The fuel cell system according to claim 1, further comprising a switching unit that switches whether or not the refrigerant passes through the catalytic combustor based on the temperature of the heat exchange fluid. The catalytic combustor scavenging means stops the supply of the scavenging gas to the catalytic combustor when the cumulative supply time of the scavenging gas to the catalytic combustor reaches a predetermined time. The fuel cell system according to claim 3. The catalytic combustor scavenging means stops the supply of the scavenging gas to the catalytic combustor when the integrated supply amount of the scavenging gas to the catalytic combustor reaches a predetermined supply amount. The fuel cell system according to claim 3. The catalytic combustor scavenging means is the oxidant gas supply means, and the scavenging gas is an oxidant gas discharged from the oxidant gas supply means,
The oxidant gas supply means supplies the oxidant gas to the catalytic combustor so as not to run out of the oxidant gas in the fuel cell, corresponding to the consumption amount of the oxidant gas in the fuel cell. The fuel cell system according to any one of claims 1 to 5. A fuel cell that generates electricity by being supplied with fuel gas and oxidant gas;
Oxidant gas supply means for supplying oxidant gas;
Heat exchange fluid circulation means for circulating the heat exchange fluid so as to pass through the fuel cell;
A catalytic combustor for catalytically burning a fuel gas and an oxidant gas and heating a circulating heat exchange fluid;
Catalytic combustor scavenging means for scavenging the catalytic combustor with scavenging gas;
With
The fuel cell and the catalytic combustor are arranged in parallel with the oxidant gas supply means,
A fuel cell system operating method in which the catalyst combustor warms up the fuel cell via a heat exchange fluid when it is determined to warm up the fuel cell at the time of system startup,
After it is determined that the warm-up of the fuel cell is completed, scavenging gas is supplied from the catalytic combustor scavenging means to the catalytic combustor, and the catalytic combustor is scavenged. Method.

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