JP2013137948A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of avoiding erroneous detection of a combustion state of a combustor as extinction.SOLUTION: When extinction estimation means 24 estimates an extinction state, a controller 23 for controlling a generation output of a fuel cell 12 increases an output command value of the fuel cell more than an output command value before an extinction state is estimated to continue power generation of the fuel cell. Otherwise, when stopping the operation of a fuel cell system and then operating the fuel cell system, the controller 23 controls so that an output command value of the fuel cell is increased more than an output command value before an extinction state is estimated.

Description

  The present invention relates to a fuel cell system in which the combustion state of a combustor is not erroneously detected as fire extinguishing.

  In general, when power is generated by a fuel cell system, a source gas such as city gas is reformed into a hydrogen-rich fuel gas by a hydrogen generator and supplied to the fuel cell. The reforming in the hydrogen generator is carried out by catalytic reaction, but this reaction is endothermic and requires a certain amount of heat energy, so it is equipped with a combustor to heat the hydrogen generator, where it is mainly off-fuel. Gas (the fuel gas after reaction discharged from the fuel cell contains combustible components) is burned. The combustor takes in fresh air from the outside of the fuel cell system as combustion air to maintain the combustion state.

  However, since the power generation amount of the fuel cell changes according to the load, the amount and composition of the off-fuel gas also change accordingly. The amount of combustion air is adjusted so that stable combustion is possible even in such a state, but if there is a sudden change in the amount of power generation, the combustion state also deteriorates, and in some cases the flame of the combustor is extinguished There is a case.

  In order to cope with such a problem, when the output current is reduced according to a change in the external load, the reduction rate of the flow rate of the oxidant gas is equal to or greater than the reduction rate of the raw material gas flow rate. Thus, it is proposed to suppress fire extinguishing (misfire) by suppressing the increase in the ratio of the flow rate of the oxidant gas to the flow rate of the raw material gas. (For example, refer to Patent Document 1).

  FIG. 7 shows a conventional fuel cell system described in Patent Document 1. As shown in FIG. 7, the fuel cell system 101 includes a fuel cell 102, a raw material gas supply device 103 for supplying a raw material gas, an oxidant gas supply device 104 for supplying an oxygen-containing gas to the fuel cell, a raw material gas and water vapor. And a reformer 105 for performing a reforming reaction. The fuel cell 102 contains a fuel cell stack in which a plurality of fuel cells are arranged. The fuel cell stack is supplied with raw material gas and oxidant gas for power generation and is not used for power generation. In addition, the fuel cell 102 and the reformer 105 are heated by separately combusting the source gas and the oxidant gas.

  In such a fuel cell system, when the output current is reduced according to a change in the external load, the reduction rate of the flow rate of the oxidant gas is the same as or lower than the reduction rate of the flow rate of the raw material gas. By controlling the oxidant gas supply device and the raw material gas supply device so as to be larger than that, the ratio of the flow rate of the oxidant gas to the flow rate of the raw material gas can be suppressed and fire extinguishing (misfire) can be suppressed. Is disclosed.

JP 2010-277760 A

However, in the conventional configuration shown in FIG. 7, when the output current of the fuel cell is reduced, the ratio of the oxidant gas flow rate to the raw material gas flow rate is only restrained from relatively increasing. When using a rectifying frame rod (hereinafter simply referred to as “frame rod”), which is a flame detector widely used in equipment, it is burning smoothly. Nevertheless, it may be erroneously detected that the fire is extinguished.

  The reason for this can be explained as follows. When the output current of the fuel cell is reduced, the setting of the raw material gas flow rate and the reformer temperature is also reduced according to the degree of reduction. However, the temperature of the reformer does not decrease immediately due to the heat capacity of the reformer. As a result, the temperature of the reformer with respect to the raw material gas flow rate becomes higher than an appropriate value for a while, and the reforming efficiency during that period is high, that is, the ratio of hydrogen is high. Accordingly, the ratio of hydrogen gas in off-fuel gas also increases. When the ratio of hydrogen gas increases, the output current of the flame rod decreases correspondingly, so that there is a problem that it is determined that the fire is extinguished even though combustion in the combustor is continuing smoothly. .

  Here, the reason why the output current of the flame rod decreases as the ratio of hydrogen gas in the off-fuel gas increases will be described below. The flame rod outputs the strength of conductivity by the ionic substance generated according to the flame condition as a current value. The fire extinguishing estimation means of the fuel cell system estimates that the fire extinguishing state is obtained when the output current of the frame rod becomes a predetermined threshold value or less. In combustion with hydrocarbon gas used as a raw material gas for fuel cell systems such as methane and propane, there are many ionic substances in the flame due to the molecular structure of the gas components. When it becomes smaller, there is no problem even if it is determined that the combustion state is unstable or the fire is extinguished. On the other hand, combustion with hydrogen gas reduces the amount of ionic substances present in the flame as compared with combustion with hydrocarbon gas. Along with this, the output current of the frame rod is also reduced, and if it is determined based on the same standard as that of the hydrocarbon-based gas, it is erroneously detected that the fire is extinguished despite good combustion.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a fuel cell system in which the combustion state of the combustor is not erroneously detected as extinguishing.

  In order to solve the above-described conventional problem, the fuel cell system of the present invention increases the output command value of the fuel cell and continues the power generation of the fuel cell when the fire extinguishing estimation means estimates that the fire is extinguished, or When the operation of the fuel cell system is stopped and thereafter the operation of the fuel cell system is performed, the output command value of the fuel cell is controlled to be increased.

  As a result, even when the load of the fuel cell system is reduced, the flow rate of the raw material gas can be secured at a certain level or higher, so that the reformer temperature does not decrease to a predetermined temperature when the output of the fuel cell is reduced. However, since the reforming efficiency is not excessively increased and the ratio of the methane gas in the off-fuel gas is ensured to be a certain level or more, it is possible to prevent the fire extinguishing estimation unit from finally making a false judgment that the fire is extinguished.

  The fuel cell system of the present invention can provide a fuel cell system in which the combustion state of the combustor is not erroneously detected as fire extinguishing.

The figure which shows the structure of the fuel cell system which concerns on Embodiment 1 and 2 of this invention. The figure which shows the output change of the fuel cell system which concerns on Embodiment 1 and 2 of this invention The flowchart which shows the driving | operation operation | movement of the fuel cell system which concerns on Embodiment 1 of this invention. The flowchart which shows the driving | operation operation | movement of the fuel cell system which concerns on Embodiment 2 of this invention. The figure which shows the structure of the fuel cell system which concerns on Embodiment 3 of this invention. The figure which shows the structure of the fuel cell system which concerns on Embodiment 4 of this invention. The figure which shows the structure of the conventional fuel cell system

  According to a first aspect of the present invention, there is provided a fuel cell system comprising: a fuel cell that generates power by reacting a fuel gas and an oxidant gas; and reforming a raw material gas containing at least a hydrocarbon gas and water vapor; A hydrogen generating device that generates at least an off-fuel gas discharged from the fuel cell, and a combustor that heats the hydrogen generating device, and supplies combustion air to the combustor A combustion air supply device, a fire extinguishing estimation means for estimating whether the flame of the combustor is in a combustion state or a fire extinguishing state, and a controller for controlling the power generation output of the fuel cell. And when the said fire extinguishing estimation means estimates that the fire extinguishing state, the controller raises the output command value of the fuel cell from the output command value before estimating the fire extinguishing state, and continues the power generation of the fuel cell. Alternatively, when the operation of the fuel cell system is stopped and then the operation of the fuel cell system is performed, control is performed so that the output command value of the fuel cell is increased from the output command value before estimating the fire extinguishing state. As a result, even when the output value of the fuel cell is lowered, the flow rate of the raw material gas can be maintained at a certain level or more, so that a decrease in the ratio of methane gas in the off-fuel gas can be suppressed, and thereby the fire extinguishing estimation means can The operation of the fuel cell system can be continued without erroneous detection.

  In the fuel cell system according to a second aspect of the invention, in particular, in the first aspect of the invention, the controller sets the supply command value of the raw material gas supplied to the hydrogen generator when the fire extinguishing estimating means estimates that the fire extinguishing state is in the fire extinguishing state. When the fuel cell system continues to generate power by increasing the supply command value before the estimation, or the operation of the fuel cell system is stopped and then the fuel cell system is operated, the fuel cell system is supplied to the hydrogen generator. The supply command value of the raw material gas to be controlled is controlled to be higher than the supply command value before the fire extinguishing state is estimated. As a result, even when the output value of the fuel cell is lowered, the flow rate of the raw material gas can be maintained at a certain level or more, so that a decrease in the ratio of methane gas in the off-fuel gas can be suppressed, and thereby the fire extinguishing estimation means can The operation of the fuel cell system can be continued without erroneous detection.

  A fuel cell system according to a third aspect of the present invention includes the flame detection device for detecting the combustion state of the combustor based on the current value generated by receiving the flame of the combustor, particularly in the first or second aspect of the invention. An estimation means makes it the structure which estimates that it is a fire extinguishing state, when the electric current value measured with the flame detection apparatus falls below the predetermined 1st electric current value. As a result, the output current of the flame detection device made of, for example, a flame rod changes depending on the state of the flame of the combustor. Therefore, the current value and the first threshold set to determine whether the combustion state is stable are set. By comparing the current value, the combustion state of the combustor can be detected appropriately.

  In a fuel cell system according to a fourth aspect of the invention, particularly in the third aspect of the invention, the controller is configured such that the current value measured by the flame detector is a first operation time or a first number of times, and the first current value. When the current value is larger than the second current value, the output command value of the fuel cell is returned to the output command value before the increase. As a result, the output command can be returned to the original value after the hydrogen ratio of the off-fuel gas returns to the normal range, so that the combustion state of the combustor can be extinguished even when the output of the fuel cell is reduced. The operation of the fuel cell system can be continued without erroneous detection.

In the fuel cell system according to a fifth aspect of the invention, particularly in the first or second aspect of the invention, the hydrogen generator detects a reformer that performs a reforming reaction between a raw material gas and water vapor, and a temperature of the reformer. A first temperature at which the controller is controlled so that the controller reduces the power generation output of the fuel cell, and the temperature of the reformer is predetermined. When it is above, it is estimated that the fire is extinguished. As a result, it can be determined that the combustion state of the combustor is unstable without checking the output value of the flame detection device, so that it is necessary to shift to the fire detection detection avoidance operation in which the output command value of the fuel cell is increased in advance. The power generation operation of the fuel cell system can be continued without erroneously detecting the combustion state of the combustor as extinguishing.

  In the fuel cell system according to a sixth aspect of the invention, in particular, in the fifth aspect of the invention, the controller has a temperature detected by the temperature detector lower than the first temperature for a second operation time or a second number of times that is predetermined. When the temperature falls below the second temperature, the output command value of the fuel cell is returned to the output command value before the increase. This makes it possible to determine that the combustion state of the combustor has stabilized without checking the output value of the flame detection device, so that the combustor 7 is not erroneously detected as extinguished even when the output of the fuel cell is reduced. The operation of the fuel cell system can be continued.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to this embodiment.

(Embodiment 1)
FIG. 1 shows the configuration of a fuel cell system 1 according to Embodiment 1 of the present invention. The components of the fuel cell system 1 are housed in a housing 2. In FIG. 1, a hydrogen generator 3 includes a reformer 4 that reforms a raw material gas into a hydrogen-rich gas, a CO converter 5 that transforms CO generated in the reformer 4, and a CO that removes the contained CO. It consists of a remover 6. A combustor 7 is provided to heat the hydrogen generator 3 including the reformer 4 to an appropriate temperature.

  The source gas is supplied from the outside of the system and introduced into the hydrogen generator 3 at an appropriate flow rate by the source gas supply device 8 and the source gas flow meter 9. In addition, combustion air is supplied to the combustor 7 at an appropriate flow rate by the combustion air supply device 10 and the combustion air flow meter 11 so that the combustion in the combustor 7 becomes an optimum state.

  The fuel gas generated by the hydrogen generator 3 is supplied to the anode electrode of the fuel cell 12. On the other hand, air outside the casing 2 humidified to an appropriate dew point by the humidifier 14 as an oxidant gas containing oxygen is supplied to the cathode electrode of the fuel cell 12 by the oxidant gas supply device 13.

  The off-fuel gas discharged from the anode electrode of the fuel cell 12 is supplied to the combustor 7 after recovering heat in the condenser 15 and separating condensed water. The condensed water separated from the condenser 15 is collected in the condensed water tank 17. On the other hand, the off-oxidant gas discharged from the cathode electrode of the fuel cell 12 recovers the heat in the condenser 16 and separates the condensed water, and is then released to the outside of the system. The condensed water separated from the condenser 16 is collected in the condensed water tank 17. Further, the combustion exhaust gas discharged from the hydrogen generator 3 is discharged to the outside of the housing 2 after recovering heat in the condenser 18 and separating condensed water. The condensed water separated from the condenser 18 is collected in the condensed water tank 17.

  The water collected in the condensed water tank 17 is stored in the water tank 20 by the water supply pump 19. The water stored in the water tank 20 is supplied as cooling water to the fuel cell 12 by the cooling water circulation pump 21, and heat generated during power generation in the fuel cell 12 is recovered in the circulating water. The heat recovered in the circulating water is stored in hot water stored in an external hot water storage tank (not shown) by the heat exchanger 22. The heat recovered from the condensers 15, 16 and 18 is also stored in the hot water stored in the external hot water storage tank.

  A controller 23 is disposed inside the housing 2. The controller 23 converts the direct current generated by the fuel cell 12 into an alternating current. Further, it is also connected to various actuators used in the fuel cell system 1 to control these. Fire extinguishing estimation means 24 is formed inside the controller.

  The operation and action of the fuel cell system 1 configured as described above will be described below. At the start of the fuel cell system, the temperature of the hydrogen generator 3 is raised by a heater (not shown) attached to the hydrogen generator 3. When the hydrogen generator 3 rises to a temperature necessary for reforming the raw material gas, the raw material gas is supplied to the hydrogen generator 3 and a hydrogen-rich fuel gas is generated. When the fuel gas is generated by the hydrogen generator 3, the water in the water tank 20 is supplied to the hydrogen generator 3 by driving the reforming water supply pump 27 as water necessary for the reforming reaction.

  The fuel gas generated by the hydrogen generator 3 is supplied to the fuel cell 12 and is generated by a reaction with the air supplied by the air pump 13 and humidified by the humidifier 14. The fuel gas used for power generation in the fuel cell 12 is discharged from the fuel cell 12 as an off-fuel gas containing residual combustible components that have not been used for the cell reaction, and heat recovery and condensed water are collected by the condenser 15. After separation, it is supplied to the combustor 7. The off-fuel gas supplied to the combustor 7 is used as a combustion gas for maintaining the temperature of the hydrogen generator 3. Combustion exhaust gas generated by combustion in the combustor 7 is discharged to the outside of the housing 2 after heat recovery and condensed water are separated by a condenser 18 disposed in the middle.

  Next, the operation when the power load of the fuel cell system 1 is reduced will be described with reference to FIGS. When the power load of the fuel cell system decreases (S11), an output target value corresponding to the power load of the fuel cell system is set (S12), and the fuel cell system is set at a predetermined decrease rate toward the output target value. The output command value is decreased (S13). In accordance with the degree of reduction, the supply target amount of the raw material gas and the set target value of the temperature of the reformer 4 are also reduced to predetermined values.

  However, the hydrogen generation apparatus 3 including the reformer 4 may estimate that the fire extinguishing estimation means is in a fire extinguishing state without the temperature decreasing at a predetermined speed due to the heat capacity of the constituent material, the heat insulating material, and the like (S14). ). In that case, by raising the output command value of the fuel cell from the output command value before estimating the fire extinguishing state (S15), the temperature of the reformer 4 becomes a temperature corresponding to the reset output command value of the fuel cell. Since it approaches, the fire extinguishing estimation means does not estimate the fire extinguishing state, and the operation of the fuel cell system can be continued (S17). If the fire extinguishing estimation means does not estimate that the fire is extinguished, the output command value of the fuel cell is continuously reduced, and when it reaches the same value as the output target value, the reduction of the output command value is finished (S16) and the operation is continued as it is. (S17).

  Also, once the operation of the fuel cell system is stopped and then the fuel cell system is operated, the output command value of the fuel cell is increased from the output command value before estimating the fire extinguishing state, thereby the reformer Since the temperature of 4 approaches the temperature corresponding to the output command value of the reset fuel cell, the fire extinguishing estimation means does not estimate the fire extinguishing state, and the fuel cell is not erroneously detected as a fire extinguishing state. System operation can be continued.

  In the present embodiment, the case where the power load of the fuel cell system is reduced is described as a condition in which the combustion state of the combustor may be erroneously detected as fire extinguishing. Needless to say, the present invention can be similarly applied when the temperature of the reformer becomes higher than a predetermined value due to excessive temperature rise or load fluctuation during the temperature operation, or when the supply amount of the raw material gas decreases due to some factor. .

(Embodiment 2)
The configuration of the fuel cell system 1 according to Embodiment 2 of the present invention can be described with reference to FIG. Since the basic configuration and operation are the same as those in the first embodiment, the description of overlapping contents is omitted.

  Next, the operation when the power load of the fuel cell system 1 is reduced will be described with reference to FIGS. When the power load of the fuel cell system is reduced (S21), an output target value corresponding to the power load of the fuel cell system is set (S22), and the fuel cell system is set at a predetermined rate of reduction toward the output target value. The output command value is decreased (S23). In accordance with the degree of reduction, the supply target amount of the raw material gas and the set target value of the temperature of the reformer 4 are also reduced to predetermined values.

  However, the hydrogen generator 3 including the reformer 4 may estimate that the fire extinguishing estimation means is in a fire extinguishing state without the temperature decreasing at a predetermined speed due to the heat capacity of the constituent material, the heat insulating material, etc. (S24). ). In that case, the temperature of the reformer 4 is set to a temperature corresponding to the reset supply gas supply command value by raising the supply gas supply command value from the supply command value before the fire extinguishing state is estimated (S25). Therefore, the fire extinguishing estimation means does not estimate the fire extinguishing state, and the operation of the fuel cell system can be continued (S27). When the fire extinguishing estimation means does not estimate that the fire is extinguished, the output command value of the fuel cell is continuously decreased, and when the output target value becomes the same value as the output target value, the decrease of the output command value is finished (S26) and the operation is continued as it is. (S27).

  Also, once the operation of the fuel cell system is stopped and then the fuel cell system is operated, the supply command value of the raw material gas is increased from the supply command value before estimating the fire extinguishing state, thereby the reformer Since the temperature of 4 approaches the temperature corresponding to the reset supply gas gas supply command value, the fire extinguishing estimation means does not estimate the fire extinguishing state, and the fuel cell does not erroneously detect the combustion state of the combustor 7. System operation can be continued.

  In the present embodiment, the case where the power load of the fuel cell system is reduced is described as a condition in which the combustion state of the combustor may be erroneously detected as fire extinguishing. Hydrogen ratio in off-fuel gas even when the temperature of the reformer becomes higher than the specified value due to excessive temperature rise or load fluctuation during temperature operation, or when the supply amount of raw material gas decreases due to some factor It goes without saying that the same applies to these cases.

(Embodiment 3)
FIG. 5 shows the configuration of the fuel cell system 1 according to Embodiment 3 of the present invention. Since the basic configuration and operation are the same as those in the first embodiment, description of overlapping contents is omitted, and only different points will be described.

  In FIG. 5, in order to detect the combustion state of the combustor 7, a flame detector 25 is attached. This flame detection device 25 is connected to the fire extinguishing estimation means 24.

Next, the operation when the load of the fuel cell system 1 is reduced. As described in the first and second embodiments, when the temperature of the reformer 4 does not decrease at a predetermined speed, such a state is obtained. If the operation is continued, as described above, the hydrogen gas ratio in the off-fuel gas increases, and accordingly, the output value of the flame detection device 25 decreases. Therefore, the combustion state of the combustor 7 can be estimated by comparing the current value measured by the flame detector 25 with a predetermined first current value. Further, according to the estimation contents of the fire extinguishing estimation means 24, the output command value of the fuel cell is increased from the output command value before estimating the fire extinguishing state, or the supply command value of the raw material gas is estimated before the extinguishing state By taking measures to raise the supply command value, it is possible to continue the operation of the fuel cell system without erroneously detecting that the combustion state of the combustor 7 is extinguished.

  Further, when the current value measured by the flame detection device 25 becomes larger than the first current value, the temperature of the reformer 4 is initially set when the current value is greater than the first operation time or the first number of times determined in advance. Since it is found that the temperature has approached the temperature corresponding to the reduced rate, the output command value of the fuel cell is returned to the initial target value before the increase. By performing such control, it is possible to reduce the output value of the fuel cell to the initial target output value while avoiding the occurrence of problems due to erroneous detection of the combustion state of the combustor 7 as extinguishing.

  In the present embodiment, the current value measured by the flame detector 25 is larger than the first current value as a condition for determining the timing for returning the output command value of the fuel cell to the initial target value before the increase. Of course, this is not the case. For example, as a condition for determining the timing for returning the output command value of the fuel cell to the initial target value before the increase, the current value measured by the flame detection device 25 is a predetermined first operating time or the first number of times. By setting the current value to be greater than or equal to the second current value greater than the first current value, it is possible to provide a fuel cell system with more stability.

(Embodiment 4)
FIG. 6 shows the configuration of the fuel cell system 1 according to Embodiment 4 of the present invention. Since the basic configuration and operation are the same as those in the first embodiment, description of overlapping contents is omitted, and only different points will be described.

  In FIG. 6, a temperature detector 26 is attached to detect the temperature of the reformer 4. This temperature detector 26 is connected to the fire extinguishing estimation means 24. In the same case as in the third embodiment, the temperature of the reformer 4 detected by the temperature detector 26 is controlled to be a first temperature that is determined in advance in a state where the power generation output of the fuel cell is controlled to be reduced. When it becomes above, as it is clear from the contents described in the third embodiment, it can be estimated that the fire is extinguished. Therefore, by implementing measures to increase the output command value of the fuel cell from the output command value before estimating the extinguishing state, or to increase the supply command value of the raw material gas from the supply command value before estimating the extinguishing state As in the third embodiment, power generation can be continued without erroneously detecting the combustion state of the combustor 7 as extinguishing.

  In addition, when the temperature detected by the temperature detector 26 is lower than the first temperature for a predetermined second operation time or a second number of times, the temperature of the reformer 4 is initially reduced. Since it is directly known that the temperature has approached the temperature according to the speed, the output command value of the fuel cell is returned to the initial target value before the increase. By performing such control, it is possible to reduce the output value of the fuel cell to the initial target output value while avoiding the occurrence of problems due to erroneous detection of the combustion state of the combustor 7 as extinguishing.

  In the present embodiment, the temperature of the reformer 4 measured by the temperature detector 26 is used as a condition for determining the timing for returning the fuel cell output command value to the initial target value before the increase. Although it is assumed that the temperature is lower than the temperature, it is not limited to this. For example, as a condition for determining the timing for returning the output command value of the fuel cell to the original target value before the increase, the temperature of the reformer 4 measured by the temperature detector 26 is determined as a second operation time that is determined in advance. Alternatively, a fuel cell system with more stability can be provided by setting the second number of times to be equal to or lower than the second temperature lower than the first temperature.

In particular, if the load on the fuel cell system suddenly decreases immediately after it has increased to the rated or maximum value, it must be decreased immediately after the temperature of the reformer is increased in accordance with the output increase target set when the load increases. Since the overshoot at the time of rising also occurs, the difference between the target temperature of the reformer and the actual temperature becomes larger, and the possibility that the combustion state of the combustor is determined to be extinguished is increased. It is very effective to introduce the control method used in the fuel cell system of the present invention to a household fuel cell system in which such changes are considered to occur frequently.

  As described above, the fuel cell system of the present invention extinguishes the combustion state of the combustor by installing a flame detector such as a flame rod in the combustor or installing a temperature detector in the reformer. The operation can be continued while avoiding erroneous detection. Thereby, for example, a combustor using hydrogen gas other than a fuel cell, or an industrial combustor using a gas (for example, coke oven gas) whose output value at the flame rod is likely to decrease similarly to hydrogen. It can also be applied to.

DESCRIPTION OF SYMBOLS 1 Fuel cell system 3 Hydrogen generator 4 Reformer 7 Combustor 10 Combustion air supply device 12 Fuel cell 23 Controller 24 Fire extinguishing estimation means 25 Flame detection device 26 Temperature detector

Claims (6)

A fuel cell that generates electricity by reacting a fuel gas and an oxidant gas; and
A hydrogen generator that reforms at least a raw material gas containing a hydrocarbon gas and water vapor to generate the fuel gas containing hydrogen; and
A combustor configured to combust at least off-fuel gas discharged from the fuel cell and heating the hydrogen generator;
A combustion air supply device for supplying combustion air to the combustor;
Fire extinguishing estimation means for estimating whether the flame of the combustor is in a combustion state or a fire extinguishing state;
A controller for controlling the power generation output of the fuel cell;
With
When the controller estimates that the fire extinguishing state is a fire extinguishing state, the controller increases the output command value of the fuel cell from the output command value before estimating the fire extinguishing state, and continues the power generation of the fuel cell, or When stopping the operation of the fuel cell system and then operating the fuel cell system, control to increase the output command value of the fuel cell from the output command value before estimating the fire extinguishing state,
Fuel cell system.   When the fire extinguishing estimation means estimates that the fire extinguishing state, the controller raises the supply command value of the raw material gas supplied to the hydrogen generator above the supply command value before estimating the fire extinguishing state to generate power from the fuel cell. Or when the operation of the fuel cell system is stopped and then the fuel cell system is operated, the supply command before the supply command value of the raw material gas supplied to the hydrogen generator is estimated to be in the fire extinguishing state The fuel cell system according to claim 1, wherein the fuel cell system is controlled so as to be higher than a value. A flame detection device that detects a combustion state of the combustor according to a current value generated by receiving the flame of the combustor;
3. The fuel cell system according to claim 1, wherein the fire extinguishing estimation unit estimates a fire extinguishing state when the current value measured by the flame detection device falls below a predetermined first current value. When the current value measured by the flame detection device is greater than the first current value, the first operation time or the first number of times determined in advance, the controller outputs an output command value of the fuel cell. Return to the output command value before increasing.
The fuel cell system according to claim 3. The hydrogen generator includes a reformer that performs a reforming reaction between a raw material gas and water vapor, and a temperature detector that detects a temperature of the reformer,
The fire extinguishing estimation means controls the controller to reduce the power generation output of the fuel cell, and when the temperature of the reformer is equal to or higher than a predetermined first temperature, The fuel cell system according to claim 1, wherein the fuel cell system is estimated. The controller increases the output command value of the fuel cell when the temperature detected by the temperature detector becomes lower than the first temperature for a predetermined second operation time or second number of times. Return to the output command value before
The fuel cell system according to claim 5.

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