JP2001052728A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of making power generation of the fuel cell system continue at a low output while preventing a fuel cell stack from being poisoned, when the pressure of a reformed gas in a reformer rises, if the output of the fuel cell system is rapidly lowered. SOLUTION: If the output of a fuel cell stack 5 is rapidly lowered, the most proper amount of required air supply required for the fuel electrode of a fuel cell stack 5 is computed based on the pressure of a reformed gas in a reformer 1 read from a pressure detector 67 in order to increase the amount of air supply to the fuel electrode of the fuel cell stack 5, when the pressure of the reformed gas in the reformer 1 rises by making the opening of a first solenoid valve 43 small, and a sixth solenoid valve 53 is controlled so as to have this required amount of air supply.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fuel cell system provided with a fuel cell stack.

[0002]

2. Description of the Related Art As a conventional fuel cell system, for example, a system disclosed in JP-A-6-76847 is known.

[0003] This system includes a reformer, a carbon monoxide converter, and a fuel cell stack, and the concentration of carbon monoxide (CO) in the reformed gas delivered from the carbon monoxide converter is measured by an electrode of the fuel cell stack. When the catalyst is in an operating state that poisons the catalyst harmfully, the reformed gas sent from the carbon monoxide converter flows through the flow path that bypasses the fuel cell stack, so that the reforming gas containing high concentration of carbon monoxide can be obtained. The purpose of the present invention is to prevent the supply of high quality gas to the fuel cell stack and prevent the fuel cell stack from being poisoned.

[0004]

However, such a conventional fuel cell system has a problem that when the output of the fuel cell system is rapidly reduced, no output can be obtained.

[0005] That is, when the state of charge of the secondary battery is close to the upper limit and the secondary battery cannot be charged much, the output of the fuel cell system may be rapidly reduced. At this time, if the output decrease of the fuel cell stack (decrease in the amount of hydrogen used) is faster than the response of the output decrease of the reformer (decrease in the supply amount of fuel and water), surplus reform not consumed by the fuel cell stack is performed. Since the quality gas (hydrogen) increases, the reformed gas (hydrogen) wastefully consumed in the combustor increases, and the efficiency of the fuel cell system decreases.

As a method for avoiding this, it is conceivable to temporarily store the generated reformed gas in the reformer and then supply the reformed gas to the fuel cell stack in an amount corresponding to the output. . However, when the reformed gas is accumulated in the reformer, the pressure of the reformed gas in the reformer increases, so that it becomes difficult for air to enter a carbon monoxide converter or the like, and the carbon monoxide is selected. The oxidation reaction is no longer performed sufficiently, the amount of conversion (conversion) of carbon monoxide to carbon dioxide is reduced, and the carbon monoxide (CO) removal rate in the carbon monoxide converter is reduced. Will poison it.

On the other hand, when the reformed gas flows by bypassing the fuel cell stack as in the above-mentioned conventional fuel cell system, poisoning of the fuel cell stack is prevented, but the fuel cell stack is not poisoned. Since no reformed gas is supplied at all, no output can be obtained at all.

[0008] The present invention has been made in view of the above,
The purpose is to prevent poisoning of the fuel cell stack when the pressure of the reformed gas in the reformer increases when the output of the fuel cell system is suddenly reduced.
An object of the present invention is to provide a fuel cell system capable of continuing low-power generation of a fuel cell stack.

[0009]

According to the first aspect of the present invention,
In order to solve the above problems, a reformer for reforming a fuel to generate a reformed gas containing hydrogen, and a carbon monoxide for removing carbon monoxide contained in the reformed gas generated by the reformer A fuel cell stack comprising: a removing device; and a fuel cell stack configured to generate electric power by using a reformed gas supplied from the carbon monoxide removing device and air supplied from an air supply source. A first flow control valve for adjusting the flow rate of the reformed gas supplied to the fuel cell stack from the fuel cell stack; and a second flow control adjusting the flow rate of the air supplied from the air supply source to the fuel electrode of the fuel cell stack A valve,
Pressure detection means for detecting the pressure of the reformed gas in the reformer, and when the pressure of the reformed gas in the reformer rises by reducing the opening of the first flow control valve, Calculating the optimum required air supply amount required for the fuel electrode of the fuel cell stack based on the pressure of the reformed gas in the reformer to increase the amount of air supply to the fuel electrode of the fuel cell stack The gist of the present invention is to have control means for controlling the second flow control valve so as to achieve the required air supply amount.

According to a second aspect of the present invention, there is provided a fuel cell stack, comprising: a stack cooling means for adjusting a cooling water flow rate for supplying cooling water to the fuel cell stack; In order to increase the amount of cooling water supplied to the fuel cell stack in accordance with the increase in the amount of air supplied to the fuel electrode, the optimum required amount of cooling water required for cooling the fuel cell stack is calculated. The gist of the present invention is to control the stack cooling means so as to attain the required cooling water supply amount.

According to a third aspect of the present invention, in order to solve the above-mentioned problem, a second carbon monoxide removing device is provided downstream of the first flow control valve, and the second carbon monoxide removing device flows out of the second carbon monoxide removing device. The gist is that a reformed gas cooling means for cooling the reformed gas is provided.

[0012]

According to the first aspect of the present invention, when the output of the fuel cell system is rapidly reduced, the opening of the first flow control valve is reduced to reduce the reformed gas in the reformer. When the pressure of the fuel cell stack increases, the optimum demand for the fuel electrode of the fuel cell stack based on the pressure of the reformed gas in the reformer to increase the amount of air supply to the fuel electrode of the fuel cell stack By calculating the air supply amount and controlling the second flow control valve so as to achieve the required air supply amount, it is possible to prevent the fuel cell stack from being poisoned and continue the low-power generation of the fuel cell stack. Can be.

According to the present invention, cooling water is supplied to the fuel cell stack, and the cooling water is supplied to the fuel cell stack in accordance with an increase in the amount of air supplied to the fuel electrode of the fuel cell stack. In order to increase the cooling water supply amount of the fuel cell stack, the optimum required cooling water supply amount required for cooling the fuel cell stack is calculated, and by controlling the stack cooling means to achieve the required cooling water supply amount, the fuel It is possible to prevent overheating of the fuel cell stack due to heat of oxidation reaction of carbon monoxide in the cell stack.

According to the third aspect of the present invention, a second carbon monoxide removing device is provided downstream of the first flow control valve.
When the output of the fuel cell system is rapidly reduced by providing a reformed gas cooling unit for cooling the reformed gas flowing out of the second carbon monoxide removing device, Since the discharged reformed gas is supplied to the fuel cell stack after being cooled, the reformed gas is efficiently supplied to the second carbon monoxide removing device without being restricted by the upper limit of the temperature rise of the fuel cell stack. It is possible to set a temperature at which carbon monoxide can be removed, and the second carbon monoxide removing device can efficiently remove carbon monoxide.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 1 is a diagram showing a configuration of a fuel cell system according to an embodiment. In FIG. 1, a reformer 1 has a catalyst layer filled with a reforming catalyst, and uses water (pure water) to produce methanol or a petroleum-based fuel (here, methanol will be described as an example). ) Is steam reformed to generate a reformed gas containing a large amount of hydrogen. At this time, in some cases, reforming by partial oxidation of methanol is performed using air (compressed air) supplied from the compressor 11 through the air supply path 27. Steam reforming is an endothermic reaction, and partial oxidation reforming is an exothermic reaction. The reformed gas generated in the reformer 1 is sent to a carbon monoxide converter (carbon monoxide removing device) 3 through a reformed gas supply path 19. The air supply path 27 is connected to the fourth
The reformed gas supply path 19 includes a solenoid valve 49 and a ball valve (check valve) 55, and a pressure detector (pressure detection) for detecting the pressure of the reformed gas in the reformer 1 (reformer internal pressure). (Means) 67.

The carbon monoxide converter 3 converts (converts) carbon monoxide contained in the steam reformed gas from the reformer 1 into carbon dioxide to reduce the carbon monoxide concentration. Generates reformed gas. Also at this time, in some cases, reforming by partial oxidation of residual methanol is performed using air (compressed air) supplied from the compressor 11 through the air supply passage 29. The reformed gas whose carbon monoxide has been reduced to a low concentration in the carbon monoxide converter 3 is sent to the fuel cell stack 5 through the reformed gas supply path 21. The air supply path 29
Has a fifth solenoid valve 51 and a ball valve (check valve) 57, and the reformed gas supply passage 21 has a first solenoid valve (first flow control valve) 43 whose opening can be adjusted. . An air supply passage 33 for supplying air (compressed air) from the compressor 11 is provided downstream of the first electromagnetic valve 43 of the reformed gas supply passage 21.
The air supply path 33 also includes a sixth solenoid valve (second flow control valve) 53 and a ball valve (check valve) 59 whose opening can be adjusted.

The fuel cell stack 5 uses the reformed gas from the carbon monoxide converter 3 and the air from the compressor 11, and more specifically, uses the hydrogen in the reformed gas and the oxygen in the air to form a battery. A reaction is generated to generate electricity. At this time, the reformed gas and the air supplied to the fuel cell stack 5 are not all consumed in the fuel cell stack 5 but are discharged leaving a part thereof as surplus discharged reformed gas and discharged air. All are sent to the combustor 7 through the exhaust reformed gas supply passage 23 and the exhaust air supply passage 25, respectively. The exhaust reformed gas supply passage 23 includes a second electromagnetic valve 45, and the exhaust air supply passage 25 includes a third electromagnetic valve 47.

The combustor 7 causes a combustion reaction between the exhaust hydrogen in the surplus exhaust reformed gas discharged from the fuel cell stack 5 and the exhaust oxygen in the exhaust air. At this time, although not shown, in some cases, the exhaust reformed gas and the exhaust air from the fuel cell stack 5 are burned together with the air from the compressor 11 and methanol as the fuel. Then, the combustion gas generated in the combustor 7 is sent to the reformer 1 and the evaporator 9 through the combustion gas supply path 35. The reaction heat required for steam reforming in the reformer 1 is covered by the combustion heat in the combustor 7. The combustion gas supply path 35 includes a temperature detector 69 for detecting the temperature of the combustion gas (combustor temperature). The combustion gas that has passed through the reformer 1 and the evaporator 9 is exhausted to the atmosphere by an exhaust gas exhaust passage 37 as exhaust gas.

The evaporator 9 recovers the heat of the combustion gas discharged from the combustor 7 to evaporate methanol and water (pure water). That is, the heat of the combustion reaction in the combustor 9 is transferred to the evaporator 9 by the combustion gas, and is reused to evaporate methanol and water. The methanol and water evaporated by the evaporator 9 are sent to the reformer 1 as methanol vapor and steam, respectively. Note that methanol is supplied from the methanol tank 13 to the evaporator 9 via the fuel supply path 39, and water (pure water) is supplied from the water tank 15 to the water supply path 41.
Is supplied to the evaporator 9. The fuel supply path 39 includes a fuel pump 61, and the water supply path 41 includes a water pump 63.

The cooling of the fuel cell stack 5 is performed by a cooling device (stack cooling means) 17 using cooling water. The cooling device 17 has a function of forcibly circulating cooling water through the fuel cell stack 65, and includes, for example, a radiator,
It is composed of a pump, a cooling fan, etc. The cooling water circulates through the cooling water passage 65 to the fuel cell stack 5.

The secondary battery 71 includes the fuel cell stack 5
In addition to accumulating surplus power generated by the motor and regenerative power generated by a drive motor system (not shown) when the fuel cell vehicle decelerates, traveling power consumed by the drive motor system,
If the fuel cell stack 5 does not generate enough power to supply auxiliary power consumed by the compressor 11, the reformer 1, the combustor 7, the solenoid valves, the pumps, and the like, the fuel cell stack 5 discharges. Power is supplied to the drive motor system and auxiliary equipment (compressor 11, reformer 1, combustor 7, etc.) to compensate for the insufficient power. Such power distribution is performed by the power control circuit 73. The power control circuit 73 is connected to a control unit 75 for comprehensively controlling the fuel cell system. The control unit 75 inputs signals from various sensors and switches, performs various arithmetic processes, and comprehensively controls each part of the fuel cell system.

In particular, the control unit 75 has an RO storing control programs and various control maps therein.
M, having a RAM as a work area at the time of control,
In a case where the output of the fuel cell system is rapidly reduced, each unit is controlled based on an input signal from a predetermined sensor such as the pressure detector 67 to prevent the fuel cell stack from being poisoned and to reduce the fuel cell stack low. Output power generation is continued.

Next, the control operation of the fuel cell system will be described with reference to the control flowchart shown in FIG. The control flowchart shown in FIG. 2 is stored as a control program in the internal ROM of the control unit 75.

First, in step S10, the control unit 75 determines whether or not the output of the fuel cell stack 5 is rapidly reduced. This determination is made based on whether the secondary battery 71 can be charged because the state of charge of the secondary battery 71 is close to the upper limit. If the state of charge of the secondary battery 71 is close to the upper limit and the state cannot be charged to the secondary battery 71, it is determined that there is a request to rapidly reduce the output of the fuel cell system, and the process proceeds to step S20. On the other hand, when the state of charge of the secondary battery 71 is not close to the upper limit and the secondary battery 71 can be charged, it is determined that there is no request to rapidly decrease the output of the fuel cell system, and the apparatus stands by.

In step S20, the control unit 75 reduces the opening of the first solenoid valve 43 to reduce the amount of hydrogen used by the fuel cell stack 5,
The opening degree is set according to the target output after the output of the fuel cell stack 5 is reduced. As a result, the flow rate of the reformed gas supplied from the reformer 1 to the fuel cell stack 5 via the carbon monoxide converter 3 is reduced, and the reformed gas is accumulated in the reformer 1 and the fuel cell stack 5 5, the flow rate of the exhaust reformed gas supplied to the combustor 7 is reduced.

At the same time, in step S30, the fuel pump 61 is operated to reduce the output of the reformer 1.
And the water pump 63 to adjust the flow rates of methanol and pure water supplied from the methanol tank 13 and the water tank 15 to the evaporator 9 to values corresponding to the target output after the output of the fuel cell stack 5 is reduced. I do. The required methanol flow rate and the required pure water flow rate at this time are, for example, the required methanol flow rate and the required pure water flow rate assigned to the required methanol flow rate map and the required pure water flow rate map with respect to the output of the fuel cell stack 5 from the internal ROM. Obtained by reading.

When the processes in steps S20 and S30 are performed, the output of the fuel cell stack may decrease at a speed exceeding the response speed of the reformer 1, and in this case,
Since the reformed gas is accumulated in the reformer 1, the pressure of the reformed gas in the reformer 1 (internal pressure of the reformer) increases, and air (compressed) is supplied to the reformer 1 and the carbon monoxide converter 3. Air) is less likely to enter (reduction of the amount of air supplied to the carbon monoxide converter 3), the selective oxidation reaction of carbon monoxide is not sufficiently performed, and the amount of carbon monoxide converted (converted) into carbon dioxide is reduced. And the carbon monoxide (CO) removal rate in the carbon monoxide converter 3 decreases. Therefore, in the first embodiment, by repeating the processing from step S40 to step S100, the poisoning of the fuel cell stack 5 is prevented, and the low-power generation of the fuel cell stack 5 is continued. In addition, the reformed gas accumulated in the reformer 1 is gradually consumed to reduce the internal pressure of the reformer and thereby recover the carbon monoxide (CO) removal rate in the carbon monoxide converter 3. As a result, a stable normal operation state corresponding to a low output is realized for the reformer 1 finally.

In step S40, the combustion gas supply path 35
The temperature of the combustion gas (the temperature of the combustor 7) is read from the temperature detector 69 provided in the. In step S50, control is performed to maintain the temperature of the combustor 7 (the temperature of the combustion gas generated by the combustion reaction) based on the temperature of the combustion gas read from the temperature detector 69. Specifically, for example, as the flow rate of the exhaust reformed gas supplied to the combustor 7 through the fuel cell stack 5 is reduced, the exhaust reformed gas is similarly supplied to the combustor 7 through the fuel cell stack 5. The opening degree of the third solenoid valve 47 is controlled so as to reduce the flow rate of the exhaust air, and the ratio between the exhaust reformed gas supplied to the combustor 7 and the exhaust air is suitable for the combustion reaction in the combustor 7. Adjust so that the ratio is correct.

In step S60, the internal pressure of the reformer (the pressure of the reformed gas in the reformer 1) is read from the pressure detector 67 provided in the reformed gas supply passage 19. And
In step S70, the opening of the first solenoid valve 43 is adjusted so that the internal pressure of the reformer does not exceed the pressure resistance of the reformer 1 and becomes too large.

In step S80, CO flows into the fuel stack 5 due to a decrease in the CO removal rate in the carbon monoxide converter 3 due to an increase in the internal pressure of the reformer due to accumulation of the reformed gas in the reformer 1. In order to cope with the increase in the amount, based on the reformer internal pressure (the pressure of the reformed gas in the reformer 1) read in step S60, the air supply amount to the fuel electrode of the fuel cell stack is increased. Then, an optimum required air supply amount required for the fuel electrode of the fuel cell stack 5 is calculated, and the opening degree of the sixth solenoid valve 53 is controlled so as to achieve the required air supply amount. As described above, when the internal pressure of the reformer increases, the amount of air supplied to the fuel electrode of the fuel cell stack 5 is increased in anticipation of an increase in carbon monoxide downstream of the carbon monoxide converter 3. This promotes the selective oxidation reaction of carbon monoxide, thereby preventing the fuel cell stack 5 from being poisoned by carbon monoxide. The required air supply amount at this time can be obtained, for example, by reading the required air supply amount assigned to the required air supply amount map for the reformer internal pressure from the internal ROM.

In this case, the reformed gas accumulated in the reformer 1 is gradually consumed, the internal pressure of the reformer is reduced, and the carbon monoxide (CO) removal rate of the carbon monoxide converter 3 is reduced. , The required air supply amount is also gradually reduced toward the normal operation state.

Further, in step S90, step S90
In order to increase the amount of cooling water circulation to the fuel cell stack 5 in accordance with the increase in the amount of air supply to the fuel electrode of the fuel cell stack 5 at 80, the optimum required amount of cooling water circulation required for cooling the fuel cell stack 5 is determined. It calculates and controls the pump of the cooling device 17 so as to achieve the required cooling water circulation amount. As described above, by increasing the amount of circulation of the cooling water to the fuel cell stack 5 in accordance with the increase in the amount of air supplied to the fuel electrode of the fuel cell stack 5, the heat of oxidation reaction of carbon monoxide in the fuel cell stack 5 is increased. Overheating of the fuel cell stack 5 is prevented. The required cooling water circulation amount at this time can be obtained, for example, by reading the required cooling water circulation amount assigned to the required cooling water circulation amount map for the reformer internal pressure from the internal ROM.

Then, in step S100, it is determined whether or not the internal pressure of the reformer has stabilized. If the internal pressure of the reformer is not stable during rising or falling, the process returns to step S40. On the other hand, when the internal pressure of the reformer becomes stable, it is determined that the stable normal operation state corresponding to the low output with respect to the reformer 1 has been reached, and a series of processing ends.

As a result, the effect of the first embodiment is that, when the output of the fuel cell stack 5 is suddenly reduced, the opening of the first solenoid valve 43 is reduced, and the reformer 1 The reformed gas can be stored in the inside. As a result, the fuel passes through the fuel cell stack 5 and the combustor 7
The flow rate of the exhaust reformed gas supplied to the fuel cell is reduced, and is consumed more wastefully (as heat energy in the exhaust gas) in the combustor 7 than in the power generation in the fuel cell stack 5 and the reaction heat in the reformer 1. The amount of the reformed gas can be reduced, and the efficiency of the fuel cell system can be improved.

In addition, when the output of the fuel cell stack 5 is suddenly reduced, a sudden increase in the supply amount of the exhaust reformed gas to the combustor 7 can be reduced, so that the capacity of the combustor 7 can be reduced. .

Further, the internal pressure of the reformer increases due to the accumulation of the reformed gas in the reformer 1, and in this operation state, the air is sent to the carbon monoxide removing device such as the carbon monoxide converter 3 in order to send air. Must use a compressor that compresses the air to increase the pressure of the air even further.
Since the pressure of the reformed gas downstream of 3 is lower than the inside of the reformer 1, the pressure of the compressed air can be set higher than that of the reformed gas, and there is no need to provide a high-pressure type compressor.

When the internal pressure of the reformer rises, the sixth
By adjusting the opening of the control valve 53 to increase the amount of air supplied to the fuel electrode of the fuel cell stack 5 to remove carbon monoxide, the carbon monoxide converter attached to the reformer 1 is increased. Even when the carbon monoxide removal rate in the fuel cell stack 3 decreases, the fuel cell stack 5 can continue to generate low output power while preventing poisoning of the fuel cell stack 5.

(Second Embodiment) FIG. 3 is a diagram showing a configuration of a fuel cell system according to a second embodiment of the present invention. Note that the second embodiment has the same basic configuration as the fuel cell system corresponding to the first embodiment shown in FIG. 1, and the same components are denoted by the same reference numerals. , The description of which will be omitted.

The feature of the second embodiment is that, as shown in FIG.
Downstream, in turn, a second small carbon monoxide converter 81
And a heat exchanger (reformed gas cooling means) 83 for cooling the reformed gas flowing out of the carbon monoxide converter 81. Since the second carbon monoxide converter 81 is located downstream of the first solenoid valve 43, even if the pressure of the reformer 1 or the first carbon monoxide converter 3 is kept high, the pressure is reduced. Can be set lower. Further, the second carbon monoxide converter 81 is used for removing carbon monoxide when the output of the fuel cell stack 5 sharply decreases and the flow rate of the reformed gas supplied to the fuel cell stack 5 is small. Since it is used, the capacity can be reduced.

The control operation of the fuel cell system according to the present embodiment can be described with reference to the control flowchart shown in FIG. 2. However, the control operation is the same as that described in the first embodiment. Is omitted.

As a result, the effect of the second embodiment is the same as that of the first embodiment.
By providing a second small carbon monoxide converter 81 downstream of the first solenoid valve 43 and providing a heat exchanger 83 downstream of the carbon monoxide converter 81, a second carbon monoxide converter is provided. 81
Is supplied to the fuel cell stack 5 after being cooled by the heat exchanger 83, so that the reformed gas is not restricted by the upper limit of the temperature rise of the fuel cell stack 5 and the second carbon monoxide conversion The temperature setting at which the carbon monoxide can be removed efficiently can be performed on the converter 81, and the carbon monoxide can be removed efficiently by the second carbon monoxide converter 81.

[Brief description of the drawings]

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

FIG. 2 is a control flowchart for explaining a control operation of the fuel cell system according to the first embodiment.

FIG. 3 is a diagram showing a configuration of a fuel cell system according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 reformer 3 carbon monoxide converter 5 fuel cell stack 7 combustor 9 evaporator 11 compressor 13 methanol tank 15 water tank 17 cooling device 43, 45, 47, 49, 51, 53 solenoid valve 67 pressure detector 71 2 Secondary battery 73 Power control circuit 75 Control unit 81 Carbon monoxide converter 83 Heat exchanger

Claims (3)

[Claims] 1. A reformer for reforming a fuel to generate a reformed gas containing hydrogen, and a carbon monoxide removing device for removing carbon monoxide contained in the reformed gas generated by the reformer. And a fuel cell stack that generates electricity using the reformed gas supplied from the carbon monoxide removal device and air supplied from an air supply source. A first flow control valve for adjusting the flow rate of the reformed gas supplied to the fuel cell stack; a second flow control valve for adjusting the flow rate of air supplied from the air supply source to the fuel electrode of the fuel cell stack; Pressure detecting means for detecting the pressure of the reformed gas in the reformer; and when the pressure of the reformed gas in the reformer increases by reducing the opening of the first flow control valve, To the fuel electrode of the fuel cell stack Calculating the optimum required air supply amount required for the fuel electrode of the fuel cell stack based on the pressure of the reformed gas in the reformer so as to increase the required air supply amount. Control means for controlling the second flow control valve so that 2. A fuel cell stack, comprising: cooling means for adjusting a flow rate of cooling water for supplying cooling water to the fuel cell stack, wherein the control means adjusts an amount of air supplied to a fuel electrode of the fuel cell stack. In order to increase the supply amount of cooling water to the fuel cell stack, an optimum required cooling water supply amount required for cooling the fuel cell stack is calculated, and the stack cooling means is set to the required cooling water supply amount. The fuel cell system according to claim 1, wherein the fuel cell system is controlled. 3. A second carbon monoxide removing device, and a reformed gas cooling means for cooling the reformed gas flowing out of the second carbon monoxide removing device, downstream of the first flow control valve. The fuel cell system according to claim 1, wherein the fuel cell system is provided.