JP2000208162A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the concentration of carbon monoxide in reformed gas supplied from a reformer to a fuel cell as much as possible to prevent poisoning of a catalyst and to improve power generation efficiency. SOLUTION: In a fuel cell system which generates an electromotive force by an electrochemical reaction of a reformed gas supplied from a reformer, a temperature of a predetermined portion in the reformer, a concentration of carbon monoxide in the reformed gas, and a fuel Reformed gas supply permitting means (steps S2, S3, S4) for permitting the reformer to supply the reformed gas from the reformer to the fuel cell when any two of the battery voltage-related amounts satisfy a predetermined condition. , S6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell comprising a reformed fuel composed of a hydrocarbon such as methyl alcohol and water and reformed into a desired reformed gas such as a hydrogen-rich gas by a reformer. And a fuel cell system that obtains an electromotive force by supplying power to the fuel cell.

[0002]

2. Description of the Related Art In a fuel cell, an electrochemical oxidation reaction between a fuel gas and oxygen is caused through a polymer electrolyte membrane, a molten carbonate, a solid electrolyte, or the like, and an electromotive force accompanying the reaction is taken out. It is configured. If the fuel cell is of a fixed installation type, fuel gas supplied from a gas cylinder or gas tank can be used, but if the fuel cell is of a mobile type mounted on a vehicle or the like, it can be replaced with fuel gas. Use hydrocarbons that are easy to handle, such as methanol,
This is converted into a hydrogen-rich reformed gas by a reformer, and the reformed gas is used as a fuel gas for a fuel cell.

[0003] One example is described in Japanese Patent Application Laid-Open No. Hei 8-29312. The configuration is briefly described. A mixed steam of methanol and water is supplied to a reformer equipped with a reforming catalyst to cause a steam reforming reaction of methanol, and a hydrogen-rich reforming reaction product is produced. The electrolyte gas is supplied to a fuel cell using a polymer membrane as an electrolyte, an oxidation reaction between oxygen and hydrogen in the air is caused to occur through the electrolyte membrane, and an electromotive force associated therewith is taken out. . The fuel cell includes a platinum catalyst in a reaction layer of a fuel electrode. On the other hand, carbon monoxide gas is inevitably generated with the reforming reaction of methanol. Since the platinum is poisoned and deteriorated by the carbon monoxide gas, a CO converter is provided between the reformer and the fuel cell in order to remove the carbon monoxide gas.

As a general tendency, when the reforming reaction by the reforming catalyst does not proceed efficiently or when the temperature of carbon dioxide accompanying the reforming reaction of hydrocarbons is high, the reforming reaction or carbon dioxide Carbon monoxide is likely to be generated by the reversible reaction, and when such conditions are satisfied, the concentration of carbon monoxide in the reformed gas increases. Therefore, in the invention described in the above publication, the temperature in the reformer is detected, and when the temperature is not within the allowable range, the supply of the reformed gas to the fuel cell is stopped. As another condition, when the CO concentration in the reformed gas is detected by a CO sensor and the CO concentration exceeds an allowable value,
The supply of the reformed gas to the fuel cell is stopped.

[0005]

The steam reforming reaction of hydrocarbons is usually carried out using a reforming catalyst, but when the temperature of the reforming catalyst has not reached the activation temperature or, conversely, it has exceeded. In such a case, the quality of the reformed gas deteriorates, for example, the efficiency of the reforming reaction deteriorates, the amount of generated carbon monoxide increases, and the amount of residual hydrocarbons increases. Particularly, in a reformer in a fuel cell system mounted on a vehicle, the reformer is operated / stopped according to the output required of the fuel cell. It is likely that the quality of the quality gas will be reduced.

In the apparatus described in the above-mentioned publication,
Such a state in which the activity of the reforming catalyst is low is detected by the temperature, and the concentration of carbon monoxide in the reformed gas is estimated.
The temperature of all parts of the reformer cannot be detected, and the reformer temperature and the carbon monoxide concentration do not always correspond exactly. There is a high possibility that poisoning of the platinum catalyst will occur when supplied to the battery. In the device described in the above publication,
Although the CO sensor detects the concentration of carbon monoxide in the reformed gas, the accuracy of detecting the concentration of carbon monoxide by the conventional CO sensor is not always high. Probably there was a possibility to be supplied to the battery. In addition, if a CO sensor is used, the number of components of the system increases, so that there is a disadvantage that the equipment cost is increased.

The present invention has been made in view of the above circumstances, and has as its object to provide a fuel cell system capable of effectively suppressing the flow of carbon monoxide from a reformer into a fuel cell. Is what you do.

[0008]

In order to achieve the above object, the present invention provides a fuel which generates an electromotive force by an electrochemical reaction of a reformed gas supplied from a reformer. In the battery system, when any two of the temperature at a predetermined location in the reformer, the concentration of carbon monoxide in the reformed gas, and the voltage-related amount of the fuel cell satisfy predetermined conditions, the fuel from the reformer is discharged from the reformer. The fuel cell system further comprises a reformed gas supply permission unit for permitting the supply of the reformed gas to the battery.

Therefore, according to the first aspect of the present invention, the temperature of a predetermined portion in the reformer, the concentration of the carbon monoxide gas in the reformed gas itself, and the reforming gas, which cause the generation of carbon monoxide during the reforming reaction, When at least any two of the three quantities related to the voltage in the fuel cell according to the concentration of carbon monoxide in the gas satisfy predetermined conditions, the reformed gas from the reformer to the fuel cell Supply is allowed. That is, according to the first aspect of the present invention, the low carbon monoxide concentration in the reformed gas is determined based on at least the above two conditions. Is reliably prevented.

Further, according to the present invention, in a fuel cell system which generates an electromotive force by an electrochemical reaction of a reformed gas supplied from a reformer, the temperature of a predetermined portion in the reformer and the reformed gas First condition satisfaction determining means for determining that one of the carbon monoxide concentration in the reforming gas satisfies a predetermined condition, and the temperature of a predetermined portion in the reformer and the carbon monoxide concentration in the reformed gas. When the first condition satisfaction determination means determines that one of the conditions satisfies a predetermined condition, the second condition is satisfied for determining that the voltage-related amount of the fuel cell satisfies a predetermined condition. Determining means for permitting supply of reformed gas from the reformer to the fuel cell when the second condition satisfaction determining means determines that the voltage-related amount of the fuel cell satisfies a predetermined condition; Reforming gas And it is characterized in that it comprises a supply authorization means.

Therefore, according to the second aspect of the present invention, as the first condition for determining the carbon monoxide concentration, either one of the temperature at a predetermined location in the reformer and the carbon monoxide concentration in the reformed gas is determined. Is determined, and if the first condition is satisfied, it is determined as a second condition whether the voltage-related amount in the fuel cell satisfies a predetermined condition. . The voltage-related quantity as the second condition is
Reacts significantly with the amount of carbon monoxide in the reformed gas,
It is accurately determined whether to supply the reformed gas to the fuel cell. Further, prior to that, since the temperature of a predetermined portion of the reformer or the concentration of carbon monoxide was detected by a sensor in the reformed gas, it was confirmed that the concentration of carbon monoxide gas in the reformed gas was somewhat low. Later, since the reformed gas for detecting the voltage-related amount is supplied to the fuel cell, it is possible to prevent the reformed gas having a high carbon monoxide concentration from being supplied to the fuel cell.

According to a third aspect of the present invention, in the configuration of the first or second aspect, the reformer includes a reforming section for causing a reforming reaction of the reformed fuel, A carbon monoxide oxidizing section including an oxidation catalyst for oxidizing the carbon oxide gas, wherein the temperature of the reforming section, the temperature of the carbon monoxide oxidizing section, and the temperature of the most easily wetted portion of the oxidation catalyst are respectively Temperature determining means for determining that the temperature at a predetermined location of the reformer satisfies a predetermined condition by reaching a predetermined reference temperature according to It is.

Therefore, according to the third aspect of the present invention, all of the temperature of the reforming section, the temperature of the carbon monoxide oxidizing section, and the temperature of the most humid portion of the carbon monoxide oxidizing catalyst, which are factors causing generation of carbon monoxide, are reduced. Since it is determined that the predetermined condition is satisfied, it is possible to accurately grasp the state of generation of carbon monoxide in the reformer and the progress of oxidation for removing carbon monoxide.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on a specific example shown in the drawings. First, a reformer using methanol and water as a reforming fuel is used as a reformer, and a fuel cell is used as an energy converter for converting reformed gas generated from the reformer into another form of energy. The system that has been described will be described. FIG. 4 schematically shows an example of such a case. A reformer (MR) 2 is connected to a fuel electrode (hydrogen electrode) side of a fuel cell (FC) 1. The reformer 2 reforms a mixture of methanol and water, which are reforming fuels, into hydrogen and carbon dioxide, and includes a heating unit 3 for heating the reforming fuel, a reforming unit 4, A CO oxidation unit 5.

The heating unit 3 is for heating the reformed fuel to generate a mixed vapor of methanol and water. The heating unit 3 generates a heat for heating, and the reformed fuel is heated by the heat. And an evaporating section 7 for evaporating. The combustion unit 6 may have a structure in which the combustion raw material is burned by a burner, a structure in which the combustion raw material is oxidized by a catalyst, or the like. Therefore, a pump 8 for supplying methanol, which is an example of a heating fuel, is connected to the combustion unit 6 via an injector 9, and an air supply unit 10 for supplying air, which is an example of a supporting gas, is provided. . The air supply unit 10 is specifically constituted by an air pump. Further, a pump 11 is connected to the evaporating section 7 as a reforming fuel supply section for supplying a mixed liquid of methanol and water.
The evaporating section 7 and the combustion section 6 are connected to a heat exchanger 12
Are connected so that heat can be transferred.

The reforming section 4 is configured to generate a hydrogen-rich gas mainly by a reforming reaction between methanol and water. Specifically, the activation temperature is 280 ° C.
Using a copper-based catalyst of a certain degree, a reforming reaction mainly composed of hydrogen gas is generated by a reforming reaction of CH ₃ OH + H ₂ O → CO ₂ + 3H ₂ (1). The reforming section 4 generates hydrogen gas and heat by a partial oxidation reaction of methanol. For this purpose, air is supplied from an air supply section 13. That is, the reforming reaction represented by the above formula (1) is an endothermic reaction, whereas the reaction of the following formula (2), which is a partial oxidation reaction of methanol, is an exothermic reaction. By balancing the calorific value, the temperature of the reforming section 4 is maintained substantially constant. CH ₃ OH + ＯO ₂ → 2H ₂ + CO ₂ (2)

The reforming reaction represented by the above equation (1) and the partial oxidation reaction represented by the above equation (2) are reactions in an ideal state.
Also, since carbon dioxide changes reversibly to carbon monoxide,
In practice, carbon monoxide gas is inevitably mixed into the reformed gas. Since this carbon monoxide causes poisoning of the catalyst of the hydrogen electrode in the fuel cell 1, a CO oxidizing unit 5 is provided to remove this. This CO oxidation part 5
A CO oxidation catalyst is provided, and an air supply unit 14 is provided. By passing the reformed gas generated in the reforming unit 4, carbon monoxide contained in the reformed gas is oxidized by oxygen in the air. It is configured as follows.

On the other hand, in the fuel cell 1, as an example, a proton permeable polymer membrane is used as an electrolyte, and a hydrogen electrode (fuel electrode) 15 and an oxygen electrode (air electrode) 16 are provided with the electrolyte membrane interposed therebetween. A large number of cells having such a configuration are connected in series and parallel. Each of the electrodes 15 and 16 is composed of a diffusion layer and a reaction layer.
For example, it has a porous structure in which a catalyst such as platinum, an alloy thereof, or ruthenium is supported on carbon. The reformer 2 is connected to the hydrogen electrode 15, and a reformed gas mainly composed of hydrogen gas is supplied thereto.
An air supply unit 17 such as a pump is connected to the oxygen electrode 16 to supply oxygen for reacting with hydrogen in the reformed gas.

Note that a battery 18 and an inverter 19 are connected to the electrodes 15 and 16 as external loads so as to form a closed circuit. Further, a current sensor 20 is interposed in this closed circuit. Further, the inverter 19 includes:
The motor 21 is connected. The motor 21 is, for example, a power source for running the vehicle.

The reformer 2 and the fuel cell 1, ie, C
A switching valve 22 is provided in the middle of a pipe connecting the outlet of the O-oxidizing section 5 and the inlet of the hydrogen electrode 15. This switching valve 2
2 is configured to be electrically controlled to selectively communicate the CO oxidizing unit 5 with the hydrogen electrode 15 and a predetermined exhaust unit (not shown). The switching valve 22 and the hydrogen electrode 15
The air pump of the air supply unit 17 is connected between the fuel cell 1 and the air pump to supply air to the hydrogen electrode 15 at a predetermined time when the reformed gas is not supplied to the fuel cell 1.

FIG. 5 is a diagram showing a control system of the switching valve 22. The temperature sensor 2 for detecting the temperature Tr of the reforming section 4 is shown in FIG.
3 are provided. Preferably, the temperature sensor 23 detects the outlet temperature of the reforming section 4 and outputs a signal. The CO oxidizing unit 5 has a temperature sensor 24 for detecting a representative temperature Tco of the oxidation catalyst.
And a temperature sensor 25 for detecting a temperature Tcw of a portion where the oxidation catalyst is most likely to be wet, that is, a portion where water vapor and residual methanol in the reformed gas are easily condensed and wet. In addition, these temperature sensors 24 and 25
It is configured to output the detected temperature as an electric signal.

A CO concentration sensor 26 for detecting the concentration of carbon monoxide in the reformed gas flowing inside the pipe connecting the reforming section 4 and the switching valve 22 is provided. The CO concentration sensor 26 outputs an electric signal according to the concentration of carbon monoxide in the gas. further,
A flow control valve 27 that can electrically control the opening degree is provided in a pipe that supplies air from the air supply unit 17 to the hydrogen electrode 15.

The sensors 23, 24, 2
5 and 26 are connected to an electronic control unit (ECU) 28, and are configured to input respective detection signals to the electronic control unit 28. This electronic control unit 28
The microcomputer is mainly configured by a microcomputer, and performs an operation based on a program stored in advance, input data, and data stored in advance, and controls the switching valve 22 and the flow regulating valve 27. A control signal is output, the switching valve 22 is appropriately switched, and
Further, the opening of the flow control valve 27 is controlled.

Next, the operation of the above-described apparatus, that is, an example of control by the electronic control unit 28 will be described. FIG. 1 is a flowchart for explaining an example of the control. First, the start-up control of the reformer 2 is executed (Step S).
1). This includes control for establishing a normal operation state including a temperature rise of the reforming section 4 in a short time.
Next, it is determined whether the first condition is satisfied (step S2). One example is shown as a subroutine in FIG.

That is, it is determined whether or not the representative temperature Tco of the CO oxidizing section 5 is within the activation temperature range of the oxidation catalyst (Tco1 (for example, 90 ° C.) and Tco2 (for example, 130 ° C.)) (step). S21). This temperature range is a temperature determined by the carbon monoxide oxidation catalyst used. If the representative temperature Tco of the CO oxidizing unit 5 falls within the activation temperature range, the activity of the oxidation catalyst is good,
Therefore, carbon monoxide in the reformed gas is oxidized and removed as much as possible.

If a negative determination is made in step S21, the process returns. If an affirmative determination is made, the temperature (outlet temperature) Tr of the reforming unit 4 is reduced to the lower limit temperature (for example, 280) at which a large amount of carbon monoxide is generated. C) It is determined whether or not it is Tr0 (step S22). Since the carbon monoxide in the reformed gas is generated by the reversible reaction of carbon dioxide generated by the steam reforming reaction of methanol at a high temperature, the reversible reaction is suppressed if the determination is affirmative in step S22. Therefore, the generation of carbon monoxide is small.

If a negative determination is made in step S22, the process returns. If an affirmative determination is made, it is determined whether or not the temperature Tcw of the portion of the CO oxidation unit 5 where the oxidation catalyst is most likely to be wet is equal to or higher than a predetermined temperature Tcw0. Is determined (step S
23). This determination reference temperature Tcw0 is a temperature about the condensation temperature of a mixed liquid of methanol and water as reforming fuel.
That is, since the CO oxidation catalyst functions to promote its oxidation by contact with carbon monoxide, the oxidation of carbon monoxide is hindered when the surface area of the reforming raw material is reduced by adhering. Therefore, if the temperature is high enough to be affirmed in step S23, it means that the surface area of the CO oxidation catalyst has been secured and the oxidation of carbon monoxide has progressed.

If a negative determination is made in step S23, the process returns. If an affirmative determination is made, a flag Flg1 indicating the establishment of the temperature condition is set to "1" (step S24). That is, the temperature of the CO oxidizing unit 5 is within the activation temperature range, the representative temperature of the reforming unit 4 is out of the temperature range in which a large amount of carbon monoxide is generated (low temperature), Is satisfied, the flag Flg1 is set to "1", and it is determined that the first condition is satisfied. In other words, in step S2, the value of the flag Flg1 is determined.

Next, it is determined whether the second condition is satisfied (step S3). This is because the carbon monoxide concentration Nco (ppm) in the reformed gas detected by the CO concentration sensor 26 described above.
Is determined by determining whether or not the density is lower than a predetermined reference value Rco (Nco <Rco). Here, the reference value Rco is, for example, 20 ppm, which is a value corresponding to the upper limit of the allowable concentration of carbon monoxide during normal operation of the fuel cell 1. The CO concentration sensor 26 directly detects the concentration of carbon monoxide in the reformed gas. However, the detected value varies, and an accurate value may not always be obtained.

In step S2, although it is determined that the temperature condition related to the generation of carbon monoxide is satisfied, the concentration of carbon monoxide in the reformed gas cannot be directly known.
However, although the concentration of carbon monoxide in the reformed gas is detected, there is a variation in the detected value, and as a result, the concentration of carbon monoxide in the reformed gas cannot be accurately determined. Therefore, following these steps, a value related to the voltage of the fuel cell 1 is detected, and it is determined whether the third condition is satisfied based on the value (step S4). Specifically, for a very short time (for example, 2 to 3 seconds), the switching valve 22 is switched to connect the reformer 2 and the fuel cell 1 to supply the reformed gas to the fuel cell 1; The open circuit voltage (OCV) at that time is detected, and it is determined whether or not the minimum value of the absolute voltage Vfc (volt) is higher than a predetermined required voltage Rfc (volt). That is, it is determined whether or not min (Vfc)> Rfc. FIG. 3 shows the current-voltage characteristic (IV characteristic) of the fuel cell 1. The higher the concentration of carbon monoxide in the reformed gas, the lower the voltage. When poisoning occurs, the effect of activation polarization is O
Appears remarkably in CV state. Therefore, it is possible to determine whether or not the concentration of carbon monoxide is an allowable concentration based on the absolute voltage in the OCV state, and this is used in step S4.

By performing the control in step S4, carbon monoxide flows into the fuel cell 1 and the hydrogen electrode 15
May be poisoned, and post-processing is performed to recover the poisoned catalyst (step S5). Specifically, air is supplied to the hydrogen electrode 15 for a very short time by opening the flow control valve 27 connected to the pipeline between the switching valve 22 and the fuel cell 1.

Then, the above steps S2, S3, S4
If the conditions determined in step (1) are satisfied, the switching valve 22 connects the reformer 2 to the fuel cell 1, and the reformed gas generated in the reformer 2 is supplied to the fuel cell 1 (step S).
6). The reformed gas supplied to the fuel cell 1 in this manner is a high-quality reformed gas having a low carbon monoxide concentration, and the poisoning of the platinum catalyst at the hydrogen electrode 15 is suppressed or prevented. 1 improves the conversion efficiency from hydrogen to electric power, and enables efficient power generation. As a result, the fuel efficiency of a vehicle equipped with the above-described fuel cell system can be improved.

In the above system, the reformed gas is supplied from the reformer 2 to the fuel cell 1 after it is confirmed that the concentration of carbon monoxide in the reformed gas generated in the reformer 2 is low. Therefore, poisoning of the catalyst in the fuel cell 1 can be prevented, and the durability or reliability of the fuel cell 1 can be improved.
Further, in the above-described system, the open circuit voltage is used in combination with other conditions as a condition for permitting the supply of the reformed gas to the fuel cell 1, so that the concentration of carbon monoxide in the reformed gas is reduced sufficiently and sufficiently. Can be detected quickly and reliably, and as a result, it is not necessary to make other determination conditions particularly strict, so that power can be generated in the fuel cell 1 in a short time after startup. That is, the starting response is improved. In addition, since a device such as a special sensor is not required for the determination based on the open circuit voltage, which makes the most reliable determination, the equipment cost is not increased, and the device becomes larger and heavier. A system that avoids or suppresses the adverse effects of carbon monoxide can be obtained.

In the above specific example, the first to the third
When all of the above conditions are satisfied, the supply of the reformed fuel from the reformer 2 to the fuel cell 1 is started. However, the present invention is not limited to the above-described specific example. When any one of the first to third conditions is satisfied, the reformer 2 may supply the reformed gas to the fuel cell 1.

As a precondition for making the above-mentioned third condition, that is, judgment based on the voltage in the OCV state, either the above-mentioned first condition based on the temperature or the second condition based on the concentration detected by the CO concentration sensor is used. You may judge that it was materialized. That is, after at least one of the first condition determination and the second condition determination with relatively low determination accuracy is performed, it is determined whether the third condition with high determination accuracy is satisfied, and The reformed gas may be supplied to the fuel cell 1. Even with such control, since the state of poisoning by carbon monoxide is determined based on the open circuit voltage, it is possible to accurately determine the concentration of carbon monoxide in the reformed gas, and at the same time, Before determining whether the third condition is satisfied, it is determined that the carbon monoxide concentration has decreased based on the temperature condition and the value detected by the CO concentration sensor, so that the catalyst of the fuel cell may be excessively poisoned. It is prevented beforehand.

Further, the present invention can be applied to a system provided with a reformer using hydrocarbon as a raw material, and is not limited to the above-described system using methanol as a raw material. Further, the gas generated from the reformer before the reformed gas is supplied from the reformer to the fuel cell is returned to the combustion section instead of being discharged to the atmosphere through the switching valve, and the reformed material is heated. May be used. The voltage-related amount of the fuel cell determined by the present invention is preferably the above-described open circuit voltage, but is not limited thereto, and may be a voltage in another circuit state.

Here, the relationship between the above specific example and the present invention will be described. Steps S3, S3, S4 and S4 shown in FIG.
The function of S6 corresponds to the reformed gas supply permission means in claim 1. The functions of steps S2 and S3 in FIG. 1 correspond to the first condition satisfaction determination means in claim 2, the function of step S4 corresponds to the second condition satisfaction determination means in claim 2, and the function of step S6 It corresponds to the reformed gas supply permission means in claim 2. Further, the functions of steps S21, S22 and S23 shown in FIG.
Corresponds to the temperature determination means.

[0038]

As described above, according to the first aspect of the present invention, the temperature of a predetermined portion in the reformer, which is a factor of generating carbon monoxide during the reforming reaction, and the carbon monoxide gas in the reformed gas Concentration itself, when at least any two of the three quantities related to the voltage in the fuel cell according to the carbon monoxide concentration in the reformed gas satisfy a predetermined condition, Since the supply of the reformed gas from the reformer to the fuel cell is permitted by judging that the concentration of carbon monoxide is low, the judgment that the concentration of carbon monoxide in the reformed gas is low becomes accurate, and as a result, To prevent the supply of carbon monoxide to the fuel cell and the resulting poisoning of the catalyst, thereby increasing the durability and reliability of the fuel cell and improving the power generation efficiency. Can be.

According to the second aspect of the present invention, as the first condition for determining the carbon monoxide concentration, one of the temperature at a predetermined location in the reformer and the carbon monoxide concentration in the reformed gas is used. It is determined whether or not a predetermined condition is satisfied. If the first condition is satisfied, it is determined as a second condition whether or not the voltage-related amount in the fuel cell satisfies the predetermined condition. Since the voltage-related amount as the second condition is significantly affected by the amount of carbon monoxide in the reformed gas, it is necessary to accurately determine whether the reformed gas can be supplied to the fuel cell. In addition, before the control, the temperature of a predetermined portion of the reformer or the concentration of carbon monoxide is detected by a sensor in the reformed gas. After confirming that it is Will be supplied to the fuel cell of the reformed gas is carried out, as a result, it is possible to prevent the high reformed gas concentration of carbon monoxide is supplied to the fuel cell in advance.

According to the third aspect of the present invention, the temperature of the reforming unit, the temperature of the carbon monoxide oxidizing unit, and the temperature of the most susceptible portion of the carbon monoxide oxidizing catalyst, which are factors causing the generation of carbon monoxide, are determined. Since it is determined that each of them satisfies the predetermined condition, it is possible to accurately grasp the generation state of carbon monoxide in the reformer and the progress of oxidation for removing carbon monoxide. The determination at the time of starting supply of the reformed gas from the fuel cell to the fuel cell can be accurately performed, and inconveniences such as a response delay at the start and poisoning of the catalyst can be prevented.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining control performed in a system of the present invention.

FIG. 2 is a flowchart illustrating an example of a subroutine for determining a first condition.

FIG. 3 is an IV characteristic diagram of a fuel cell.

FIG. 4 is a diagram schematically showing an overall configuration of a system in which a reformer is connected to a fuel cell.

FIG. 5 is a block diagram for explaining a control system of the switching valve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Reformer, 4 ... Reforming part, 22 ...
Switching valve, 23, 24, 25 ... temperature sensor, 26 ... C
O concentration sensor, 28 ... electronic control unit.

Continued on the front page (72) Inventor Masaaki Yamaoka 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Kiyomi Nagamiya 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation F-term ( Reference) 5H027 AA06 BA01 BA16 DD03 KK31 KK41 KK42 KK54 MM09

Claims (3)

[Claims] 1. A fuel cell system for generating an electromotive force by an electrochemical reaction of a reformed gas supplied from a reformer, wherein a temperature of a predetermined portion in the reformer, a concentration of carbon monoxide in the reformed gas, The fuel cell further includes a reformed gas supply permitting means for permitting supply of the reformed gas from the reformer to the fuel cell when any two of the voltage and the fuel cell voltage satisfy a predetermined condition. Characteristic fuel cell system. 2. A fuel cell system in which an electromotive force is generated by an electrochemical reaction of a reformed gas supplied from a reformer, wherein a temperature of a predetermined portion of the reformer, a concentration of carbon monoxide in the reformed gas, First condition satisfaction determining means for determining that one of the conditions satisfies a predetermined condition; and one of a temperature at a predetermined location in the reformer and a carbon monoxide concentration in the reformed gas is predetermined. A second condition satisfaction determining means for determining that the voltage-related amount of the fuel cell satisfies a predetermined condition, when the first condition satisfaction determining means determines that the fuel cell has satisfied the predetermined condition; Reforming gas supply permitting means for permitting supply of reformed gas from the reformer to the fuel cell when the second condition satisfaction determining means determines that the voltage related amount of the fuel cell satisfies a predetermined condition. Has A fuel cell system comprising: 3. The reformer includes a reforming unit that causes a reforming reaction of the reformed fuel, and a carbon monoxide oxidizing unit that includes an oxidation catalyst that oxidizes carbon monoxide gas in the reformed gas. The temperature of the reforming section, the temperature of the carbon monoxide oxidizing section, and the temperature of the most easily wetted portion of the oxidation catalyst all reach a predetermined reference temperature corresponding to the reforming section. 3. The fuel cell system according to claim 1, further comprising a temperature judging means for judging that a temperature of a predetermined portion of the vessel satisfies a predetermined condition.