JP5490493B2 - Combustion device, fuel cell system, and method for determining ignition of combustion - Google Patents

Description

  The present invention relates to a combustion apparatus, a fuel cell system, and an ignition determination method for a combustion section, and in particular, a combustion apparatus including a combustion section in which a hydrocarbon-based fuel and a hydrogen-containing gas are selectively supplied as fuel, and the combustion apparatus And an ignition determination method in the combustion section.

  Patent Document 1 discloses a temperature change on the downstream side of a combustion section that burns city gas (hydrocarbon fuel), off-gas (hydrogen-containing gas) discharged from a fuel cell, or a gas body obtained by mixing city gas and off-gas. A plurality of temperature detection means for detecting temperature changes due to the formation state (combustion state) of the flame is provided, and a misfire occurs when the temperature of the combustion gas is reduced to the temperature detection data stored in advance when the flame is not formed. A combustion apparatus for determining this is disclosed.

  Patent Document 2 discloses ignition and ignition in a combustion apparatus that generates reforming heat based on the rate of increase / decrease in the temperature of the combustion section detected by a thermocouple (increase / decrease per unit time). A combustion apparatus for detecting the presence or absence of a subsequent misfire is disclosed.

JP 2006-002991 A JP 2007-187426 A

By the way, in the structure provided with a plurality of temperature detection means as in Patent Document 1, there is a problem that the cost of the combustion apparatus increases and the combustion apparatus becomes large, and the temperature changes to a preset threshold value. Since the determination of the combustion state is performed based on whether or not, it takes time until the final determination is made.
Further, as in Patent Document 2, when ignition / misfire determination is performed based on the rate of temperature increase / decrease, there is a possibility of erroneous detection because it is easily affected by temperature fluctuations due to external factors.

In particular, when the fuel supplied to the combustion section is transferred from a hydrocarbon fuel to a hydrogen-containing gas (off gas, hydrogen-rich reformed gas, etc.), the mixed combustion state (the supply state of both the hydrocarbon fuel and the hydrogen-containing gas) is changed. Increasing the length can suppress the occurrence of misfire, but if the mixed combustion state becomes long, the temperature may increase excessively, and it is necessary to limit the mixed combustion state short.
However, if the co-firing state is shortened, the supply of the hydrogen-containing gas is unstable immediately after the transition, so that a misfire may occur, and further, the misfire may occur immediately after igniting temporarily during misfire.
Therefore, when the fuel supplied to the combustion section is transferred from the hydrocarbon-based fuel to the hydrogen-containing gas, the temperature does not change uniformly, and the increase and decrease are repeated. In the ignition determination based on the (change speed), it is difficult to make the ignition determination with high accuracy.

  Accordingly, the present invention provides a combustion apparatus, a fuel cell system, and an ignition determination method for a combustion section that can perform ignition determination at the time of transition from a hydrocarbon-based fuel to a hydrogen-containing gas with high response, high accuracy, and low cost. For the purpose.

Therefore, the combustion apparatus of claim 1 receives a combustion part to which hydrocarbon fuel and hydrogen-containing gas are selectively supplied as fuel, a temperature sensor for detecting the temperature of the combustion part, and a detection signal from the temperature sensor. An ignition determination unit that performs an ignition determination in the combustion unit, and the ignition determination unit sets the temperature of the combustion unit at the time of transition from a hydrocarbon-based fuel to a hydrogen-containing gas as an initial value of a minimum temperature, When a temperature lower than the previous minimum temperature is detected at each periodic ignition determination timing, the minimum temperature is updated to the detected temperature, and the temperature of the combustion unit is lower than the minimum temperature at the ignition determination timing. When the value is higher than the threshold value , the ignition success in the supply state of the hydrogen-containing gas is determined.
In such a configuration, the temperature of the combustion section at the time of transition from the hydrocarbon-based fuel to the hydrogen-containing gas is set as the initial value of the minimum temperature, and then a temperature lower than the minimum temperature is detected at each periodic ignition determination timing. The minimum temperature is updated to the detected temperature, and if the temperature of the combustion part is higher than the minimum temperature above the threshold at the ignition determination timing , in other words, the temperature at the ignition determination timing is higher than the minimum temperature , and When the difference exceeds the threshold value, it is determined that the hydrogen-containing gas has been successfully ignited.

In the configuration of claim 1, as in claim 2, the ignition determination unit determines whether ignition has succeeded during a period from when the hydrocarbon-based fuel is transferred to the hydrogen-containing gas until a determination end timing when a predetermined determination time has elapsed. If not, it is possible to determine ignition failure in the supply state of the hydrogen-containing gas .
In such a configuration, if the ignition success is not determined until the determination end timing is reached, it is determined that the ignition has not been successful even if the ignition operation is continued for a predetermined maximum time, and the ignition has failed. (Timeout) is determined.

In the configuration of claim 2, as in claim 3, the ignition determination unit determines whether the hydrogen-containing gas is in a state where the minimum temperature at the determination end timing is higher than the lower limit combustion temperature in the supply state of the hydrogen-containing gas. Successful ignition in the supply state can be determined.
In such a configuration, even if ignition success is not determined based on the comparison between the minimum value and the detected temperature before the determination end timing, the minimum temperature when the determination end timing is reached is the supply of the hydrogen-containing gas. When the temperature is higher than the lower limit combustion temperature in the state, that is, during the period from the transition from the hydrocarbon-based fuel to the hydrogen-containing gas until the determination end timing is reached, the detected temperature does not become lower than the lower limit combustion temperature. In this case, the ignition success in the supply state of the hydrogen-containing gas is determined.

Further, in the configuration of claim 1 or 2, as in claim 4, the ignition determination unit has a state in which the temperature of the combustion unit is higher than the lower limit combustion temperature in the supply state of the hydrogen-containing gas exceeds the first predetermined time. If successful, ignition success in the supply state of the hydrogen-containing gas can be determined.
In such a configuration, even if the temperature of the combustion section is not determined to be higher than the minimum temperature beyond the threshold, the state higher than the lower limit combustion temperature in the supply state of the hydrogen-containing gas continues for the first predetermined time. For example, the ignition success in the supply state of the hydrogen-containing gas is determined.

Moreover, in any one structure of Claims 1-4, as in Claim 5, the ignition determination part is in a state where the temperature of the combustion part is higher than the minimum temperature exceeding the threshold and exceeds the second predetermined time. When it continues, it is possible to determine the success of ignition in the supply state of the hydrogen-containing gas , and the second predetermined time can be set to a shorter time as the temperature rise rate of the combustion section is faster .
In such a configuration, even if the temperature at that time is determined to be higher than the minimum temperature by exceeding the threshold at the ignition determination timing, the ignition success is not immediately determined, and after that, the temperature exceeds the second predetermined time. If the temperature continues to be determined to be higher than the minimum temperature by exceeding the threshold, in other words, if the temperature continues to be determined to be higher than the minimum temperature by more than a predetermined number of times, the ignition is successful. judge. Further, the second predetermined time is set to a shorter time as the rate of temperature rise in the combustion section is faster.

Moreover, in any one structure of Claims 1-5, as the claim 6, before the start of the transition from the ignition device provided in the combustion unit and the hydrocarbon-based fuel to the hydrogen-containing gas, It is preferable to further include an ignition control unit that starts the ignition operation of the ignition device and stops the ignition operation of the ignition device after the ignition determination unit determines that the ignition is successful.
In such a configuration, the ignition operation of the ignition device is started in advance before the start of the transition from the hydrocarbon-based fuel to the hydrogen-containing gas, and the ignition operation of the ignition device is stopped after a delay after the ignition determination unit determines that the ignition is successful. .

A fuel cell system according to claim 7 is provided with the combustion part in the combustion apparatus according to any one of claims 1 to 6 for heating a catalyst provided in the reformer, and supplied to the combustion part As described above, an off gas discharged from the fuel cell is used.
According to such a configuration, as a fuel for the combustion section for heating the catalyst provided in the reformer, the transition from the hydrocarbon-based fuel to the off-gas discharged from the fuel cell is performed, and the ignition in the off-gas supply state is performed. The determination is made based on the minimum temperature .

A fuel cell system according to claim 8 is provided with a combustion section in the combustion apparatus according to any one of claims 1 to 6 for heating a catalyst provided in the reformer and supplied to the combustion section. A hydrogen rich reformed gas generated by reforming a hydrocarbon-based fuel by the reformer is used as the contained gas.
According to such a configuration, as a fuel for the combustion portion for heating the catalyst provided in the reformer, the hydrocarbon fuel is changed to the hydrogen-rich reformed gas generated by reforming the hydrocarbon fuel with the reformer. The ignition determination in the supply state of the hydrogen-rich reformed gas is performed based on the minimum temperature .

An ignition determination method for a combustion section according to claim 9 is an ignition determination method for performing an ignition determination in a combustion section in which a hydrocarbon-based fuel and a hydrogen-containing gas are selectively supplied as fuel, wherein hydrogen is determined from hydrocarbon-based fuel. The temperature of the combustion section at the time of transition to the contained gas is set to the initial value of the minimum temperature, and if a temperature lower than the previous minimum temperature is detected at each periodic ignition judgment timing, the minimum temperature is set to the detected temperature. In the ignition determination timing, when the temperature of the combustion section is higher than the minimum temperature above the threshold, the ignition success in the supply state of the hydrogen-containing gas is determined.
In such a configuration, the temperature of the combustion section at the time of transition from the hydrocarbon-based fuel to the hydrogen-containing gas is set as the initial value of the minimum temperature, and then a temperature lower than the minimum temperature is detected at each periodic ignition determination timing. Then, the minimum temperature is updated to the detected temperature, and when the temperature of the combustion part is higher than the minimum temperature above the threshold at the ignition determination timing, in other words, the temperature at the ignition determination timing is higher than the minimum temperature, And when the difference is over the threshold value, it determines with having succeeded in ignition of hydrogen containing gas.

  According to the above invention, since the temperature rise in the combustion section is determined based on the lowest temperature value, the temperature rise due to successful ignition can be determined with high response and high accuracy, and a plurality of temperature sensors are not required and the cost is reduced. Can be suppressed.

1 is a schematic configuration diagram of a fuel cell system in an embodiment. It is a partial sectional view showing a burner combustor and a reformer in an embodiment. It is a flowchart which shows the starting process of a fuel cell system in case off gas is used as burner fuel in embodiment. It is a flowchart which shows the starting process of a fuel cell system in case hydrogen rich reformed gas is used as burner fuel in embodiment. It is a flowchart which shows 1st Embodiment of the ignition determination process at the time of transfer of a burner fuel. It is a time chart which shows the transfer process and ignition determination process of the burner fuel in embodiment with the temperature change of a combustion part. It is a time chart which shows the transfer process and ignition determination process of the burner fuel in embodiment with the temperature change of a combustion part. It is a flowchart which shows 2nd Embodiment of the ignition determination process at the time of transfer of a burner fuel.

Embodiments of the present invention will be described below.
FIG. 1 is a block diagram showing a fuel cell system including a combustion apparatus according to the present invention.
The fuel cell system in this embodiment performs power generation using a hydrocarbon fuel such as kerosene as a raw fuel.

As shown in FIG. 1, a fuel cell system 1 includes a desulfurizer 2, a fuel processing system (hereinafter referred to as “FPS”) 3 as a reformer, and a polymer electrolyte fuel cell (hereinafter referred to as “PEFC”) stack 4. And an inverter 5 and a housing 6 for housing them.
The desulfurizer 2 removes sulfur from a hydrocarbon fuel supplied from the outside. The desulfurizer 2 includes a desulfurization catalyst and a heater, and the desulfurization catalyst is heated to, for example, 220 ° C. to 230 ° C. by the heater and used for desulfurization treatment of hydrocarbon fuel.

The FPS 3 reforms a hydrocarbon-based fuel to generate a reformed gas (hydrogen-rich reformed gas). The reformer (hydrogen generator) 7, the burner combustor (combustion unit) 8, and the transformer 9 and a selective oxidizer 11.
The reformer 7 generates a steam reformed gas containing hydrogen by subjecting the hydrocarbon-based fuel and steam after the desulfurization process to a steam reforming reaction using a reforming catalyst.
The burner combustor 8 supplies the amount of heat necessary for the steam reforming reaction by heating the reforming catalyst of the reformer 7.

The transformer 9 performs an aqueous shift reaction of the steam reformed gas generated by the reformer 7 to generate a shift reformed gas in which the concentration of carbon monoxide CO is reduced.
In addition, the selective oxidizer 11 performs a selective oxidation reaction of the shift reformed gas generated by the transformer 9 by supplying air to further reduce the concentration of carbon monoxide CO, and the reformed gas used for the power generation reaction in the PEFC stack 4. Gas (hydrogen-rich reformed gas) is generated.

The PEFC stack 4 includes a plurality of battery cells (single cells) connected in series, and generates power using the reformed gas (hydrogen-rich reformed gas) generated by the FPS 3. Each battery cell constituting the PEFC stack 4 includes an anode, a cathode, and an electrolyte that is a solid oxide disposed between the anode and the cathode, and supplies reformed gas to the anode and air to the cathode. The power generation reaction is performed by supplying.
The inverter 5 converts the DC current output from the PEFC stack 4 into an AC current.
The casing 6 accommodates the above-described desulfurizer 2, FPS 3, PEFC stack 4 and inverter 5 in a modular manner.

The fuel cell system 1 also includes a fuel line L1 for supplying hydrocarbon fuel (gas fuel such as LPG or city gas or liquid fuel such as kerosene) to the FPS 3 from the outside of the housing 6. .
In the present embodiment, kerosene is used as the hydrocarbon fuel.
On the downstream side of the desulfurizer 2, the fuel line L 1 branches into a fuel line L 11 that supplies hydrocarbon fuel to the reformer 7 and a fuel line L 12 that supplies hydrocarbon fuel to the burner combustor 8.
The fuel line L11 and the fuel line L12 are provided with electromagnetic valves 12 and 13 for adjusting the amount of hydrocarbon-based fuel supplied to the reformer 7 and the burner combustor 8, respectively.

Furthermore, a water line L2 for supplying water (raw water) used for steam reforming to the reformer 7 is connected to the fuel line L11 in the vicinity of the reformer 7.
The water line L2 is connected to the water tank 15, and the water line L2 is provided with an electromagnetic valve 14 for adjusting the amount of water supplied to the reformer 7.
The water tank 15 is connected to a water line L21 for supplying water to the water tank 15 from the outside of the housing 6 and a recovery water line L22 for recovering process water generated by the reaction in the PEFC stack 4. .

Further, the water tank 15 is connected to a recovered water line L23 for recovering water contained in the combustion gas (exhaust gas) discharged from the burner combustor 8.
Recovery of water from the combustion gas via the recovery water line L23 is performed when a hydrogen-containing gas (off-gas or hydrogen-rich reformed gas) is burned in the burner combustor 8.
This is because the combustion gas when the hydrogen-containing gas is combusted has less oil components and can collect water with less impurities compared to the combustion gas when the hydrocarbon-based fuel is combusted in the burner combustor 8. It is.
The off-gas is a hydrogen-containing gas containing unreacted hydrogen discharged from the PEFC stack 4, and the hydrogen-rich reformed gas is a hydrogen-containing gas generated by reforming a hydrocarbon-based fuel with the FPS 3. is there.

The burner combustor 8 is connected to a burner air line L31 for supplying air from the outside of the housing 6 to the burner combustor 8. The burner combustor 8 is connected to the burner air line L31. An electromagnetic valve 16 is provided for adjusting the amount of air supplied to the air.
The PEFC stack 4 is connected to the FPS 3 via the reformed gas supply line L4, and the reformed gas (hydrogen-rich reformed gas) is supplied to the PEFC stack 4 via the reformed gas supply line L4. Supplied.

Also, a burner reforming gas supply line L14 is provided which branches from the middle of the reforming gas supply line L4 and is connected to the burner combustor 8, and an electromagnetic valve provided in the burner reforming gas supply line L14. 26 and the electromagnetic valve 27 provided in the reformed gas supply line L4 downstream of the branch portion of the burner reformed gas supply line L14, the reformed gas (hydrogen-rich reformed gas) generated by the FPS3 is controlled. Quality gas) can be supplied directly to the burner combustor 8.
The PEFC stack 4 is connected to an air introduction line L32 for introducing air from the outside of the housing 6. The air introduction line L32 is an electromagnetic valve that adjusts the amount of air supplied to the PEFC stack 4. 17 is provided.

Further, an offgas line L5 for discharging offgas containing hydrogen that has not contributed to the power generation reaction is connected to the PEFC stack 4, and the downstream side of the offgas line L5 is connected to the burner combustor 8, and burner fuel. As a result, off-gas is supplied to the burner combustor 8. The off gas line L5 is provided with an electromagnetic valve 18 for adjusting the amount of off gas supplied to the burner combustor 8.
As described above, the burner combustor 8 (combustion unit) is supplied with any one of hydrocarbon fuel, off-gas (hydrogen-containing gas), and hydrogen-rich reformed gas (hydrogen-containing gas) as electromagnetic valves 13, 18, 26. , 27 can be selectively supplied.
The system may not be provided with the burner reformed gas supply line L14 and the electromagnetic valves 26 and 27. In this case, either the hydrocarbon fuel or the off-gas (hydrogen-containing gas) is selectively burned. Will be supplied to the vessel 8 (combustion section).
Further, it is sufficient that the hydrogen-containing gas supply line has at least one of L14 and L5, and either the hydrocarbon fuel or the hydrogen-rich reformed gas is selectively burned by the burner combustor 8 (combustion). Part).
Further, methane, which is a hydrocarbon gas, may be contained in the off-gas or reformed gas, but even if it is a gas containing hydrocarbon, the gas introduced into the burner combustor 8 from L14 or L5. Is a hydrogen-containing gas.
Further, the transition from the hydrocarbon-based fuel to the hydrogen-containing gas (off-gas and / or hydrogen-rich reformed gas) may be any configuration in which the main fuel is transferred from the hydrocarbon-based fuel to the hydrogen-containing gas. Even after the transition to the gas, the case where the hydrocarbon fuel is continuously reduced and supplied to the burner combustor 8 is included in the transition from the hydrocarbon-based fuel to the hydrogen-containing gas.

Here, the structure of the said reformer 7 and the burner combustor (combustion part) 8 is demonstrated in detail.
FIG. 2 is a partial cross-sectional view of the reformer 7 and the burner combustor 8 shown in FIG.
As shown in FIG. 2, the burner combustor (combustion unit) 8 is configured to inject burner fuel (hydrocarbon fuel, off gas, hydrogen rich reformed gas) together with air, and to perform burner combustion. The combustion cylinder 21 is provided.

The burner unit 19 is connected to the fuel line L12, off-gas line L5, burner air line L31, and burner reformed gas supply line L14, and an igniter 22 is provided as an ignition device capable of performing an ignition operation continuously. The burner fuel is ignited and burned by the spark ignition of the igniter 22.
In the case of using a liquid hydrocarbon fuel such as kerosene, a vaporizer (not shown) is disposed in the fuel line L12 or the burner combustor, and the liquid hydrocarbon fuel such as kerosene is vaporized by this vaporizer. It is supplied to the combustion cylinder 21 later.
The combustion cylinder 21 defines a burner combustion space S, and combustion is performed in the combustion cylinder 21. Further, the combustion cylinder 21 is provided with a temperature sensor (thermocouple) 23 for detecting a temperature T (temperature of the combustion part) in the combustion cylinder 21.

On the other hand, a cylindrical reformer casing 24 is disposed so as to surround the outside of the combustion cylinder 21, and an annular shape is provided between the outer peripheral surface of the combustion cylinder 21 and the inner peripheral surface of the reformer casing 24. A catalyst housing space SC is formed.
In the catalyst housing space SC, a reforming catalyst container 25 formed in an annular shape is inserted into the inner peripheral surface of the reformer casing 24 and the outer peripheral surface of the combustion cylinder 21 with gaps SR1 and SR2, respectively. The gap SRE is also formed between the end surface of the reforming catalyst container 25 on the burner combustor 8 side and the end surface of the reformer casing 24 on the burner combustor 8 side.

The reforming catalyst container 25 is filled with, for example, a catalyst (reforming catalyst) 25a mainly composed of nickel or ruthenium, and a raw material gas composed of desulfurized hydrocarbon fuel and water vapor is supplied to the reforming catalyst 25a. A steam reforming reaction is performed to produce a steam reformed gas containing hydrogen.
In the reforming catalyst container 25, a partition wall 25b is formed that separates the annular space in the reforming catalyst container 25 from the inside to the outside, and the raw material gas flows from the lower end of the reforming catalyst container 25 to the inside of the partition wall 25b. After being introduced and passing through the reforming catalyst 25a on the inner side of the partition wall 25b from the lower side to the upper side, the direction is changed at the end on the burner combustor 8 side to pass through the reforming catalyst 25a on the outer side of the partition wall 25a. It passes from the upper side to the lower side, and is finally taken out from the lower end of the reforming catalyst container 25 as steam reformed gas.

An opening 24 a is formed in the peripheral wall on the lower end side of the reformer casing 24 to discharge combustion gas generated by burner combustion, and the combustion gas generated in the combustion cylinder 21 is outside the combustion cylinder 21. After moving toward the end on the burner combustor 8 side through the annular space SR1 sandwiched between the surface and the inner peripheral surface of the reforming catalyst container 25, the reformer catalyst container 25 on the burner combustor 8 side is then moved. Entering the annular space SR2 sandwiched between the inner peripheral surface of the reformer casing 24 and the outer peripheral surface of the reforming catalyst container 25 so as to wrap around the end surface and move in the direction away from the burner combustor 8. After that, it is discharged to the outside through the opening 24a.
As described above, the high-temperature combustion gas generated in the combustion cylinder 21 (combustion section) flows along the inner peripheral surface and the outer peripheral surface of the reforming catalyst container 25, so that the reforming in the reforming catalyst container 25 is performed. The catalyst 25a and the raw material gas are heated to a temperature (for example, 700 ° C. to 800 ° C.) necessary for the endothermic reaction in the reforming catalyst 25a.

Further, as shown in FIG. 2, the fuel cell system 1 includes a control device 30 that controls the entire system during operation.
The control device 30 includes a microprocessor, and controls the electromagnetic valves 13, 16, 18, 26, and 27 to control the fuel for the burner combustor 8 (hydrocarbon fuel, off gas, hydrogen rich reformed gas). ) And air supply, and the solenoid valves 12 and 14 are controlled to control the amount of hydrocarbon fuel and raw water supplied to the reformer 7, respectively.

FIG. 3 is a flowchart showing a control processing procedure executed by the control device 30 when the fuel cell system 1 is started.
The processing procedure shown in the flowchart of FIG. 3 shows a case where either hydrocarbon-based fuel or off-gas (hydrogen-containing gas) is selectively used as the fuel supplied to the burner combustor 8.
The control process shown in the flowchart of FIG. 3 is started, for example, when an ON operation signal of the start switch 31 is input to the control device 30.
First, the solenoid valves 13 and 16 are controlled to supply hydrocarbon fuel and air to the burner combustor 8 (S101), and the igniter 22 performs ignition and combustion. Thereby, the combustion exhaust gas of the burner combustor 8 heats the reforming catalyst 25a.

Until the reformed gas is generated in the FPS 3, no off-gas that can be supplied to the burner combustor 8 is generated. Therefore, at the time of start-up, a hydrocarbon-based fuel such as kerosene is used as the burner fuel to generate reformed heat. .
When the fuel cell system 1 is started up, the hydrocarbon fuel burns, so that the temperature T of the combustion part rises rapidly from room temperature, and the hydrocarbon fuel as the fuel can be stably supplied. Can be performed with high accuracy based on the fact that the rising speed of the combustion section temperature exceeds the determination speed or the combustion section temperature exceeds the ignition determination temperature.

When the temperature of the reforming catalyst 25a increases due to combustion of the hydrocarbon fuel in the burner combustor 8, the electromagnetic valves 12 and 14 are controlled to start the generation of reformed gas (hydrogen-rich reformed gas) in the FPS 3. Then, hydrocarbon fuel and raw water (raw gas) are supplied to the reformer 7 (S102).
By supplying the raw material gas, a reformed gas (hydrogen-rich reformed gas) is generated by the FPS 3, and the generated reformed gas (hydrogen-rich reformed gas) is supplied to the PEFC stack 4 via the reformed gas supply line L4. To supply.

Further, the electromagnetic valve 17 is controlled to supply air to the cathode of the PEFC stack 4 (S103).
The supply of power generation air to the PEFC stack 4 may be started before the supply of the raw material gas to the reformer 7 or at the same time as the supply of the raw material gas to the reformer 7 is started.
Thereafter, after the temperature of the PEFC stack 4 is raised to a predetermined temperature, power is taken out from the PEFC stack 4 by taking out a current from the PEFC stack 4. At this time, off-gas is discharged from the PEFC stack 4.

When off-gas is discharged from the PEFC stack 4, in order to shift the burner fuel from the hydrocarbon-based fuel to off-gas (hydrogen-containing gas), first, the electromagnetic valve 13 is controlled to carbonize the burner combustor 8. The supply of hydrogen-based fuel is stopped (S104), and then the electromagnetic valve 18 is controlled to supply off-gas to the burner combustor 8 (S105). At this time, the electromagnetic valve 16 is controlled so that the air supply amount is optimal for the combustion of off-gas.
The supply of the off-gas may be started by controlling the electromagnetic valve 18 and then the supply of the hydrocarbon fuel may be stopped by controlling the electromagnetic valve 13.

As described above, hydrocarbon fuel is used as the burner fuel supplied to the burner combustor 8 immediately after startup, but power generation by the PEFC stack 4 is started, and off-gas (hydrogen-containing gas) is discharged from the PEFC stack 4. Then, the burner fuel supplied to the burner combustor 8 is shifted from hydrocarbon fuel to off-gas (hydrogen-containing gas).
Further, the control device 30 (ignition control unit) starts a spark ignition operation in a short cycle by the igniter 22 before the start of the transition when the burner fuel is shifted from the hydrocarbon-based fuel to the off-gas, and the off-gas (hydrogen-containing) When it is determined that the ignition has succeeded in a state where the gas) is burner fuel, the spark ignition operation in a short cycle by the igniter 22 is thereafter stopped.

In the transition process from the hydrocarbon-based fuel to the off-gas, the supply of the hydrocarbon-based fuel may be stopped and the supply of the off-gas may be started substantially simultaneously, or prior to the stop of the supply of the hydrocarbon-based fuel. A process of combusting a hydrocarbon-based fuel is a mixed combustion step of supplying both the hydrocarbon-based fuel and off-gas to the burner combustor 8 by starting the supply of off-gas and then stopping the supply of hydrocarbon-based fuel. And the stroke of burning off-gas.
Moreover, it is also possible to shift from the hydrocarbon-based fuel to a hydrogen-rich reformed gas (hydrogen-containing gas), and the processing procedure for performing the burner fuel transfer processing will be described with reference to the flowchart of FIG.

The control process shown in the flowchart of FIG. 4 is started, for example, when an ON operation signal of the start switch 31 is input to the control device 30 as in the process shown in FIG.
First, the solenoid valves 13 and 16 are controlled to supply hydrocarbon fuel and air to the burner combustor 8 (S111), and the igniter 22 performs ignition combustion. Thereby, the combustion exhaust gas of the burner combustor 8 heats the reforming catalyst 25a.

Until the reformed gas is generated in the FPS 3, the reformed gas cannot be used as a burner. Therefore, at the time of start-up, a hydrocarbon-based fuel such as kerosene is used as the burner fuel to generate reformed heat.
When the fuel cell system 1 is started, the hydrocarbon-based fuel is ignited and burned, so that the temperature T of the combustion part rises rapidly from the normal temperature and the hydrocarbon-based fuel as the fuel can be stably supplied. The determination can be performed with high accuracy based on the fact that the rising speed of the combustion section temperature exceeds the determination speed, the combustion section temperature exceeds the ignition determination temperature, and the like.

When the temperature of the reforming catalyst 25a increases due to combustion of the hydrocarbon fuel in the burner combustor 8, the electromagnetic valves 12 and 14 are controlled to start the generation of reformed gas (hydrogen-rich reformed gas) in the FPS 3. Then, hydrocarbon fuel and raw water (raw gas) are supplied to the reformer 7 (S112).
When the reformed gas (hydrogen-rich reformed gas) is generated by the FPS3 by supplying the raw material gas, the burner fuel is transferred from the hydrocarbon-based fuel to the reformed gas (hydrogen-rich reformed gas). First, the electromagnetic valve 13 is controlled to stop the supply of hydrocarbon fuel to the burner combustor 8 (S113). Subsequently, the electromagnetic valves 26 and 27 are controlled to supply the reformed gas ( Hydrogen-rich reformed gas) is supplied (S114).
The supply of off-gas may be started by controlling the electromagnetic valves 26 and 27, and then the supply of hydrocarbon fuel may be stopped by controlling the electromagnetic valve 13.

At this time, the electromagnetic valve 16 is controlled to control the supply amount of air that is optimal for the combustion of the reformed gas (hydrogen-rich reformed gas), and the reformed gas (hydrogen-rich reformed gas) is burner combustor. 8 and the PEFC stack 4 can be supplied sufficiently, the electromagnetic valves 26 and 27 are controlled to provide reformed gas (hydrogen-rich reformed gas) to both the burner combustor 8 and the PEFC stack 4. Supply.
Next, the electromagnetic valve 17 is controlled to supply air to the cathode of the PEFC stack 4 (S115). The supply of power generation air to the PEFC stack 4 may be started before the supply of the raw material gas to the reformer 7 or at the same time as the supply of the raw material gas to the reformer 7 is started.

Thereafter, after the temperature of the PEFC stack 4 is raised to a predetermined temperature, power is taken out from the PEFC stack 4 by taking out a current from the PEFC stack 4. At this time, off-gas is discharged from the PEFC stack 4, but the fuel supplied to the burner combustor 8 may be shifted from the reformed gas (hydrogen-rich reformed gas) to the off-gas.
In the transition process from the hydrocarbon-based fuel to the reformed gas (hydrogen-rich reformed gas), the supply of the reformed gas (hydrogen-rich reformed gas) is started prior to stopping the supply of the hydrocarbon-based fuel, Thereafter, by stopping the supply of the hydrocarbon-based fuel, a combustion process in which both the hydrocarbon-based fuel and the reformed gas (hydrogen-rich reformed gas) are supplied to the burner combustor 8 is combusted. It can set between the process to make and the process to burn off gas.

Here, the state of the ignition determination process at the time of transition from the hydrocarbon-based fuel to the hydrogen-containing gas (off gas or hydrogen-rich reformed gas) by the control device 30, in other words, the function as the ignition determination unit of the control device 30 ( The ignition determination method) will be described with reference to the flowchart of FIG.
First, it is determined whether or not it is time to start detection of a temperature change associated with the burner fuel transition process (at the time of transition from a hydrocarbon-based fuel to a hydrogen-containing gas) (step S201).

The detection start timing of the temperature change is, for example, when a transition condition from a hydrocarbon-based fuel to a hydrogen-containing gas is satisfied (for example, when generation of off-gas or hydrogen-rich reformed gas is determined), or for burner fuel transition processing. When ignition operation by the igniter 22 is started in advance, when a predetermined time has elapsed from the start of transition, when supply of hydrocarbon fuel is cut off, when supply of hydrogen-containing gas starts, and when supply of hydrocarbon fuel is cut off It can be set after a predetermined time from the point in time or the supply start point of the hydrogen-containing gas.
When the temperature change detection start timing comes (in other words, when it is determined that the transition from the hydrocarbon-based fuel to the hydrogen-containing gas), the inside of the combustion cylinder 21 detected by the temperature sensor 23 at that time is detected. Temperature (combustion part temperature) T is read (step S202).

Next, the temperature T read at the temperature change detection start timing is set to the minimum temperature Tmin as an initial value (step S203).
Next, whether or not the elapsed time from the detection start timing has reached the maximum determination time (for example, about 4 to 10 minutes), in other words, the determination end set after the transition from the hydrocarbon fuel to the hydrogen-containing gas It is determined whether or not the timing has been reached (step S204).
The time when the maximum determination time has elapsed from the detection start timing is set as the ignition determination end timing. If the elapsed time from the detection start timing has not reached the maximum determination time, a hydrogen-containing gas (off gas or hydrogen In order to determine whether or not ignition has succeeded in the supply state of the rich reformed gas, the (latest) temperature in the combustion cylinder 21 detected by the temperature sensor 23 (the temperature of the combustion section) T is read (step S205).

Then, the lowest temperature Tmin up to the previous time is compared with the temperature T of the combustion part detected this time (step S206), and if the temperature T of the combustion part detected this time is lower than the lowest temperature Tmin up to the previous time, it is detected this time. The temperature T of the combustion part is set to the minimum temperature Tmin (step S207).
Thereby, if the temperature is decreasing due to misfire, the minimum temperature Tmin is periodically updated to the latest detected temperature.

On the other hand, if the temperature T of the combustion section detected this time is equal to or higher than the minimum temperature Tmin until the previous time, the minimum temperature Tmin is not updated, and the temperature obtained by subtracting the minimum temperature Tmin from the previous time from the temperature T of the combustion section detected this time. It is determined whether or not (an increase in the latest temperature from the minimum temperature Tmin) is equal to or greater than a threshold ΔT (for example, about 5 ° C. to 10 ° C.) (step S208).
In other words, it is determined whether or not the temperature T of the combustion portion detected by the temperature sensor 23 at the current ignition determination timing is higher than the threshold value ΔT by a minimum temperature (minimum value) Tmin.

When the minimum temperature Tmin is updated (when Tmin> T), and Tmin ≦ T, and the temperature obtained by subtracting the previous minimum temperature Tmin from the temperature T of the combustion section detected this time is a threshold value When it is determined that it is less than ΔT, the process returns to the process of determining whether or not the maximum determination time has been reached (step S204).
Thus, until the maximum determination time is reached, the minimum temperature Tmin until the previous time is compared with the temperature T of the combustion portion detected this time at every ignition determination timing at a minute time interval (constant period). The update process is repeated, and if Tmin ≦ T, the comparison between the lowest temperature Tmin and the temperature T of the combustion section detected this time is repeated.

For this reason, the minimum temperature Tmin indicates the minimum value of the temperature T of the combusting section between the temperature change detection start timing (at the time of transition from the hydrocarbon-based fuel to the hydrogen-containing gas) and the current ignition determination timing. become.
Then, if it is determined that the temperature obtained by subtracting the previous minimum temperature Tmin from the temperature T of the combustion section detected this time (the increase in the latest temperature from the minimum temperature Tmin) is greater than or equal to the threshold ΔT, Successful ignition in the supply state of gas (off-gas or hydrogen-rich reformed gas) is determined (step S209).

In other words, the temperature T of the combustion portion detected by the temperature sensor 23 at the current ignition determination timing is the lowest temperature (from the detection start timing (at the time of transition from hydrocarbon-based fuel to hydrogen-containing gas)) until this time ( If it is determined that the threshold value ΔT is higher than the minimum value Tmin, the ignition success in the supply state of the hydrogen-containing gas (off-gas or hydrogen-rich reformed gas) is determined.
When the ignition success is determined, the ignition operation of the igniter 22 is stopped later, and the operation of the fuel cell system is continued until a stop command is generated.

On the other hand, between the minimum temperature Tmin and the detected temperature T for each fixed period until the elapsed time from the start of the ignition determination reaches the maximum determination time (until the end timing of the ignition determination). If the ignition success is not determined even after repeating the comparison (ignition determination process), the minimum temperature Tmin until the maximum determination time is reached and the supply of the hydrogen-containing gas (off-gas or hydrogen-rich reformed gas) The lower limit combustion temperature Th in the state is compared (step S210).
The lower limit combustion temperature Th is a lower limit value of the combustion part temperature T when the hydrogen-containing gas (off-gas or hydrogen-rich reformed gas) is combusted, and if the hydrogen-containing gas is continuously burned, the combustion part Is a temperature at which the temperature T does not fall below.

When the maximum determination time is reached, that is, when the minimum temperature Tmin at the determination end timing is equal to or higher than the lower limit combustion temperature Th, the fuel is changed from hydrocarbon fuel to hydrogen-containing gas (off gas or hydrogen rich reformed gas). It shows that the temperature T of the combustion part has never fallen below the lower limit combustion temperature Th and has maintained the temperature equal to or higher than the lower limit combustion temperature Th until the maximum determination time has elapsed since the transition.
Here, as described above, the lower limit combustion temperature Th is a temperature at which the temperature T of the combustion section does not fall below if the hydrogen-containing gas continues to burn, and therefore the lower limit combustion temperature Th for the maximum determination time. If the above temperature is maintained, it is presumed that the ignition was successful in the supply state of the hydrogen-containing gas and the stable combustion state is maintained, so the hydrogen-containing gas (off-gas or hydrogen-rich reforming) The ignition success in the gas supply state is determined (step S209).

On the other hand, when the minimum temperature Tmin at the determination end timing is less than the lower limit combustion temperature Th, the combustion section temperature T may be less than the lower limit combustion temperature Th until the maximum determination time elapses. In other words, even if it is temporary, it indicates that a misfire has occurred. Therefore, it cannot be determined that the ignition has succeeded, and the temperature rise from the minimum temperature (minimum value) Tmin to the threshold ΔT or more is determined to be the maximum. Since it did not occur within the time, an ignition failure (timeout: time-out of the ignition process) that did not reach the ignition state within the predetermined time is determined (step S211).
If ignition failure (timeout) is determined, an alarm (warning) is issued, the supply of air, hydrocarbon fuel, raw water, etc. is stopped and the fuel cell system is reset.

Next, the operation and effect of the above-described ignition determination process will be described with reference to the time chart of FIG.
The time chart of FIG. 6 shows an example of a temperature change when the burner fuel is transferred from the hydrocarbon-based fuel to the hydrogen-containing gas.
In FIG. 6, the step of using the burner fuel as a hydrocarbon-based fuel (kerosene) is shown as step 1, and the step of using the burner fuel as a hydrogen-containing gas (off-gas or hydrogen-rich reformed gas) as step 2 is shown. is there.

In the example shown in FIG. 6, the burner fuel is transferred from the hydrocarbon-based fuel to the hydrogen-containing gas at time t2, but the ignition operation by the igniter 22 is started from time t1 before the transfer time (switching time) t2. The ignition performance of the hydrogen-containing gas can be ensured.
At time t2, when the supply of the hydrocarbon-based fuel is stopped, the supply of the hydrogen-containing gas is started almost simultaneously, and the transition from the hydrocarbon-based fuel to the hydrogen-containing gas is performed (switching), immediately after the hydrocarbon-based fuel and hydrogen The mixed gas is in a mixed combustion state, and the temperature of the combustion part may temporarily rise above the temperature (for example, about 750 ° C.) during combustion of the hydrocarbon-based fuel before switching. In the example shown in FIG. 6, the period from time t2 to time t3 is a temperature increase period due to mixed firing.

However, immediately after the transition to the hydrogen-containing gas (immediately after the start of the supply of the hydrogen-containing gas to the burner combustor 8), the supply of the hydrogen-containing gas to the burner combustor 8 is not stable, and the supply of the hydrogen-containing gas is temporarily The burner combustor 8 may misfire due to stagnation, and the temperature T of the combustion part may drop. In the example shown in FIG. 6, the period from time t3 to time t4 is a temperature drop period of the combustion section due to a temporary stagnation of the supply of hydrogen-containing gas.
Prior to stopping the supply of hydrocarbon fuel, start the supply of hydrogen-containing gas, wait for the combustion of hydrogen-containing gas to stabilize, and then stop the supply of hydrocarbon-based fuel to avoid transient misfires Then, the burner fuel can be switched. In this case, however, an excessive temperature rise is caused by the prolonged mixed firing time.

Therefore, if the co-firing time is shortened to avoid an excessive increase in temperature, the supply of the hydrogen-containing gas shifts to combustion of the hydrogen-containing gas alone in an unstable state, resulting in misfire. If an attempt is made to avoid an excessive increase in temperature, a temperature drop as shown between time t3 and time t4 in FIG. 6 may occur.
The ignition operation by the igniter 22 is continued even during the temperature drop due to the misfire as described above, and the supply stability of the hydrogen-containing gas is improved as time passes. Although it may shift to the stable combustion state of the contained gas, it may be temporarily ignited but may immediately return to the misfire state. In the example shown in FIG. 6, immediately after the temperature rises due to ignition at time t4. A case where a misfire occurs and the temperature starts to decrease again from time t5 is shown.

In the example shown in FIG. 6, since the ignition is performed at time t6 and the stable combustion state of the hydrogen-containing gas is maintained thereafter, the temperature T of the combustion portion gradually increases, and finally in the combustion state of the hydrogen-containing gas. Near the stable temperature (for example, about 730 ° C.).
In the ignition determination of the present embodiment, the ignition determination is performed when the increase with respect to the minimum temperature Tmin is equal to or greater than the threshold value ΔT. For example, in the example shown in FIG. 6, the minimum temperature Tmin is carbonized until time t3. When the hydrogen-based fuel is burner fuel, the temperature of the combustion section (for example, about 750 ° C.) is maintained, and when the temperature rises in the mixed combustion state accompanying the transition of the burner fuel, the temperature T of the combustion section becomes the minimum temperature Tmin. The temperature exceeds.

However, as the threshold value ΔT, a value that exceeds the temperature increase due to the mixed combustion state is set in advance so that the ignition determination is not made for the temperature increase due to the mixed combustion state. In other words, the burner fuel is transferred so that the temperature rise due to the mixed combustion state does not exceed the threshold value ΔT.
After the mixed combustion state, when the supply of the hydrogen-containing gas is delayed, when the temperature T of the combustion section decreases, the minimum temperature Tmin is also updated accordingly, and a temperature increase due to temporary ignition occurs. At the time t4 immediately before the start, the detected temperature at the time t4 is set to the minimum temperature Tmin.

When a temperature increase due to temporary ignition occurs, the temperature becomes higher than the minimum temperature Tmin that is the detected temperature at time t4. However, the threshold ΔT is set so that the ignition determination is not made even with respect to the temporary temperature increase. Even if the temperature T is preset and the temperature T at which the temperature reaches a peak value due to temporary ignition, the ignition success is not determined based on the relative comparison with the minimum temperature Tmin that is the detected temperature at the time t4. .
When the temperature T decreases gradually from the temporary ignition state to the misfire state, the minimum temperature Tmin is updated to a lower temperature accordingly. At time t6, the detected temperature T at that time is set to the minimum temperature. Set to Tmin.

In the temperature rise process after the time t6, the lowest temperature Tmin (the detected temperature at the time t6) is periodically compared with the latest detected temperature T, and finally the threshold ΔT is higher than the temperature T at the time t6. The ignition success is determined at the time (time t7) when the temperature becomes higher than the above.
In other words, the threshold value ΔT does not determine whether ignition has succeeded due to a temperature rise due to mixed combustion or temporary ignition, and succeeds in ignition only after the transition from the misfire state to the stable combustion state and the temperature rises smoothly. Pre-adapted to determine.

Then, the ignition operation by the igniter 22 is stopped at a time t8 when a preset delay time has elapsed from the time t7 when it was determined that ignition was successful.
As described above, since the ignition is determined based on the rise from the minimum temperature Tmin, for example, even if the rate of temperature rise (temperature rise rate) immediately after time t2, time t4, and time t6 is similar. In the temperature rise from time t2 and time t4, the deviation between the highest temperature finally reached and the temperature T at time t2 and time t4 is less than the threshold value ΔT, and successful ignition is not determined.

On the other hand, in the temperature rise from time t6, the temperature rises smoothly based on the fact that ignition was actually successful starting from the temperature T at time t6, so that it exceeds the threshold ΔT from the temperature T at time t6. When the temperature rises to a high temperature T and a temperature rise equal to or greater than the threshold value ΔT is determined (time t7), ignition success is determined.
In other words, if the temperature rises smoothly based on the fact that ignition has actually succeeded, even if the temperature rise gradient is more gradual than when the temperature rises due to mixed firing or temporary ignition, Successful ignition can be determined.

Thus, according to the ignition determination process of the present embodiment, there is no false detection of successful ignition based on a temperature increase due to co-firing or a temperature increase due to temporary ignition, and stability during combustion of the hydrogen-containing gas Since the ignition success can be determined before reaching the temperature (target temperature), and a plurality of temperature sensors are not required, the ignition success can be determined with high response and high accuracy, and the cost of the combustion apparatus can be reduced.
On the other hand, when the hydrogen-containing gas is in a stable combustion state without misfiring at the time of transition from the hydrocarbon-based fuel to the hydrogen-containing gas, as shown by a one-dot chain line in FIG. Successful ignition is determined by determining that the temperature T of the combustion section changes in the temperature range and the minimum temperature Tmin at the determination end timing is equal to or higher than the lower limit combustion temperature Th.

  In the time chart of FIG. 6, an example in which supply of hydrogen-containing gas (off gas or hydrogen-rich reformed gas) to the burner combustor (combustion unit) 8 is started substantially simultaneously with the cutoff of the supply of hydrocarbon fuel. As shown in the time chart of FIG. 7, the supply of the hydrogen-containing gas (off-gas or hydrogen-rich reformed gas) is started prior to the cutoff of the hydrocarbon-based fuel, and the carbonization is performed after the supply of the hydrogen-containing gas is started. Even in the configuration in which the supply of the hydrogen-based fuel is shut off, the same operation and effect as described above can be obtained.

By the way, in the embodiment shown in the flowchart of FIG. 5, it is determined that the current temperature T is higher than the threshold value ΔT than the minimum temperature (minimum value) Tmin between the temperature change detection start timing and the current ignition determination timing. At that time, the ignition success was determined immediately. However, the ignition success can be determined on condition that the state of ΔT ≦ T−Tmin has continued for a predetermined time or longer. This will be described with reference to the flowchart of FIG.
In the flowchart of FIG. 8, in each step of steps S221 to 227, the same processing as that of steps S201 to S207 of the flowchart of FIG.

In the second embodiment, when the minimum temperature (minimum value) Tmin is updated (step S227), it is next determined whether or not the temperature T of the combustion section detected this time is equal to or higher than the lower limit combustion temperature Th ( Step S228).
When the detected temperature T of the combustion section is equal to or higher than the lower limit combustion temperature Th, it is determined whether or not the state of T ≧ Th continues for a predetermined time or more (step S230). If the state continues for a predetermined time or more, the ignition success in the combustion using the hydrogen-containing gas (off gas or hydrogen rich reformed gas) as the burner fuel is determined (step S231).

  When the temperature T drops due to misfire, the temperature immediately falls below the lower limit combustion temperature Th, and the state of T ≧ Th does not continue for a predetermined time or longer. Therefore, the minimum temperature (minimum value) Tmin is updated. If the temperature T continues to exceed the lower limit combustion temperature Th even when the temperature T is in a lowered state, the hydrogen-containing gas is in a stable combustion state, and the hydrogen is detected from the combustion temperature of the hydrocarbon fuel. Since it is presumed that the temperature is gradually decreasing toward the combustion temperature of the contained gas, the ignition success is determined.

On the other hand, if T <Th, or if T ≧ Th and the duration is less than the predetermined time, the process returns to the process of determining whether or not the determination end timing has been reached (step S224). .
Further, it is determined that the maximum determination time (determination end timing) has not been reached (step S224), and the temperature (combustion part temperature) T in the combustion cylinder 21 detected by the temperature sensor 23 is read (step S224). S225) If it is determined that Tmin> T (step S226), the temperature obtained by subtracting the previous minimum temperature Tmin from the temperature T of the combustion section detected this time (the increase in the latest temperature from the minimum temperature Tmin) is a threshold value. It is determined whether or not ΔT (for example, about 5 ° C. to 10 ° C.) or more (whether ΔT ≦ T−Tmin is satisfied) (step S229).

In the first embodiment shown in the flowchart of FIG. 5, the ignition success is determined immediately when it is determined that ΔT ≦ T−Tmin. In the second embodiment shown in the flowchart of FIG. 8, ΔT ≦ T− If it is determined that Tmin, it is further determined whether or not the state where ΔT ≦ T−Tmin is continued for a predetermined time or more (whether ΔT ≦ T−Tmin is continuously performed for a predetermined number of times or more of the ignition determination timing). (Step S230).
Even if it is determined that ΔT ≦ T−Tmin is satisfied this time, if the duration of ΔT ≦ T−Tmin is less than the predetermined time (ignition determination timing determined as ΔT ≦ T−Tmin) If the continuous number of times is less than the predetermined number), the process returns to the step of determining whether or not the maximum determination time has passed without determining the success of ignition (step S224).

On the other hand, when the duration of ΔT ≦ T−Tmin reaches the predetermined time, it is determined whether ignition is successful in combustion using the hydrogen-containing gas (off gas or hydrogen-rich reformed gas) as the burner fuel (step S231). If the maximum determination time has passed without determining the ignition success, an ignition failure (timeout) is determined (step S232).
According to the above configuration, since the ignition success is not determined unless a temperature higher than the minimum temperature Tmin by more than the threshold value ΔT is maintained for a predetermined time or more, the accuracy of the ignition determination can be further improved, and compared with the first embodiment. Even if the threshold value ΔT is set to a smaller value, the determination accuracy can be maintained.

The predetermined time used for determining the duration of ΔT ≦ T−Tmin may be a constant value stored in advance. For example, the predetermined time may be set to a shorter time as the rate of change in the combustion section temperature T increases. The determination response can be accelerated.
When the rate of change in the combustion section temperature T is slow, it can be estimated that combustion is unstable and there is a high possibility of misfire. Therefore, in order to ensure the determination accuracy, the predetermined time is lengthened. On the other hand, when the rise in the combustion part temperature T is fast, it can be estimated that the temperature rises smoothly due to stable combustion of the hydrogen-containing gas (off-gas or hydrogen-rich reformed gas). Shorten the response of the judgment process.
Further, in the flowchart of FIG. 5 showing the first embodiment, the ignition success can be determined when the state of T ≧ Th continues for a predetermined time or more, and conversely, in the flowchart of FIG. 8 showing the second embodiment. The ignition success can be determined when the minimum temperature Tmin at the determination end timing is equal to or higher than the lower limit combustion temperature Th.
FIG. 7 shows an example in which the lower limit combustion temperature Th is lower than the combustion part temperature at the time of hydrocarbon fuel supply, but when the lower limit combustion temperature Th is higher than the combustion part temperature at the time of hydrocarbon fuel supply. The same determination can be made by setting the predetermined time determined in step S230 of FIG. 8 to be longer than the temporary temperature rise time due to co-firing.

The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the above embodiment.
For example, in the above embodiment, kerosene has been exemplified as the hydrocarbon fuel used in the burner combustor 8 (combustion unit). Further, the hydrocarbon fuel is not limited to the liquid fuel, and may be a gaseous fuel such as city gas.
Further, the temperature of the combustion section is not limited to the temperature transition tendency described in FIGS. 6 and 7 because it varies depending not only on the fuel supplied to the combustion section but also on the mounting position (sensing position) of the temperature sensor 23.
Moreover, in the said embodiment, although it was set as the fuel cell system 1 provided with the PEFC stack 4, the fuel cell system provided with the solid oxide fuel cell (SOFC) stack may be sufficient.

Further, for example, the reformer 7 and the transformer 9 are integrally formed, the reformer 7, the transformer 9 and the selective oxidation unit 11 are integrally formed, or the desulfurizer 2 and the reformer. 7 and the transformer 9 can be integrally formed.
Further, the burner combustor 8 may be used for heating a shift catalyst (for example, a mixed oxide of Fe—Cr) provided in the transformer 9.

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system 1, 3 ... Fuel processing system (FPS), 4 ... Solid polymer fuel cell (PEFC) stack, 7 ... Reformer, 8 ... Burner combustor (combustion part), 9 ... Transformer, DESCRIPTION OF SYMBOLS 11 ... Select oxidizer, 21 ... Combustion cylinder, 22 ... Igniter (ignition device), 23 ... Temperature sensor, 30 ... Control device (ignition determination part, ignition control part)

Claims (9)

A combustion section in which a hydrocarbon-based fuel and a hydrogen-containing gas are selectively supplied as fuel;
A temperature sensor for detecting the temperature of the combustion section;
An ignition determination unit that receives a detection signal of the temperature sensor and performs an ignition determination in the combustion unit;
Including
The ignition determination section,
The temperature of the combustion section at the time of transition from the hydrocarbon-based fuel to the hydrogen-containing gas is set as an initial value of the minimum temperature, and then a temperature lower than the minimum temperature is detected at each periodic ignition determination timing. Then, the minimum temperature is updated to the detected temperature, and when the temperature of the combustion section is higher than the minimum temperature by a threshold value at the ignition determination timing, the ignition success in the supply state of the hydrogen-containing gas is determined. to, the combustion device. The ignition determination unit is configured to supply the hydrogen-containing gas when the ignition success is not determined between the transition from the hydrocarbon-based fuel to the hydrogen-containing gas and the determination end timing when the predetermined determination time has elapsed. The combustion apparatus according to claim 1 , wherein ignition failure is determined in The ignition determination section, the lowest temperature in the determination end timing is higher than the lower limit the combustion temperature in the supply state of the hydrogen-containing gas, determines ignition success in the supply state of the hydrogen-containing gas, wherein Item 3. A combustion apparatus according to Item 2. The ignition determination unit is configured to supply the hydrogen-containing gas in a state where the temperature of the combustion unit is higher than a lower limit combustion temperature in the supply state of the hydrogen-containing gas for more than a first predetermined time. The combustion apparatus according to claim 1 , wherein ignition success is determined. The ignition determination section,
When the state where the temperature of the combustion part is higher than the minimum temperature and exceeds the threshold continues for a second predetermined time, it is determined whether ignition is successful in the supply state of the hydrogen-containing gas ,
The combustion apparatus according to any one of claims 1 to 4, wherein the second predetermined time is set to a shorter time as the rate of temperature rise of the combustion section is faster . The combustion device comprises:
An ignition device provided in the combustion section;
Ignition that starts the ignition operation of the ignition device before the start of the transition from the hydrocarbon-based fuel to the hydrogen-containing gas, and stops the ignition operation of the ignition device after the ignition determination unit determines successful ignition A control unit;
The combustion apparatus according to claim 1, further comprising: A combustion section in the combustion apparatus according to any one of claims 1 to 6 is provided for heating a catalyst provided in the reformer,
A fuel cell system using off-gas discharged from a fuel cell as a hydrogen-containing gas supplied to the combustion section. A combustion section in the combustion apparatus according to any one of claims 1 to 6 is provided for heating a catalyst provided in the reformer,
A fuel cell system using a hydrogen-rich reformed gas generated by reforming the hydrocarbon fuel by the reformer as a hydrogen-containing gas supplied to the combustion section. An ignition determination method for performing an ignition determination in a combustion section in which a hydrocarbon-based fuel and a hydrogen-containing gas are selectively supplied as fuel,
The temperature of the combustion section at the time of transition from the hydrocarbon-based fuel to the hydrogen-containing gas is set as an initial value of the minimum temperature, and then a temperature lower than the minimum temperature is detected at each periodic ignition determination timing. Then, the minimum temperature is updated to the detected temperature,
When the temperature of the combustion section is higher than the minimum temperature above the threshold at the ignition determination timing, it is determined whether ignition is successful in the supply state of the hydrogen-containing gas.
How to determine the ignition of a combustion part.

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