JP2016012518A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit a fuel cell system from erroneously determining that complete blow-off has occurred in a combustion unit in which unused fuel from a fuel cell is combusted.SOLUTION: A fuel cell system 100 includes: a blow-off determination unit (controller 15) for determining that complete blow-off, which is stop of combustion in a first combustion unit 36, has occurred when a second combustion unit 28's temperature T detected by a temperature sensor 28b becomes higher than a determination temperature; and a determination temperature setting unit (controller 15) that sets the determination temperature to be a first determination temperature T1 in the case that both fuel cell 34 and evaporation unit 32 show no variation that may cause temporary partial blow-off in the first combustion unit 36, and sets the determination temperature to be a second determination temperature T2 higher than the first determination temperature T1 in the case that at least one of the fuel cell 34 and evaporation unit 32 shows the variation.

Description

  The present invention relates to a fuel cell system.

  As one type of fuel cell system, one shown in Patent Document 1 is known. As shown in FIG. 1 and FIG. 2 of Patent Document 1, in the fuel cell system, the supplied reforming water is evaporated to generate water vapor, and the evaporating section (20a) that preheats the reforming raw material. ), A reforming section (22b) that generates reformed gas containing hydrogen from steam and reforming raw material, a fuel cell stack (14) that generates power using the reformed gas and air, and a fuel cell And a combustion section (18) for burning the exhaust gas discharged from the stack and heating the evaporation section and the reforming section.

  In the fuel cell system disclosed in Patent Literature 1, when the temperature of the exhaust gas exhausted from the combustion unit drops below a predetermined temperature drop amount during a predetermined determination time, combustion in the combustion unit is stopped (hereinafter referred to as the following). (Abbreviated as “complete blow-off” as appropriate).

Japanese Patent No. 4692938

  In the fuel cell system, when the amount of power generation in the fuel cell stack fluctuates, partial blowout (hereinafter, abbreviated as “partial blowout” as appropriate) may occur temporarily in the combustion section. In this case, the temperature of the exhaust gas exhausted from the combustion section drops below a predetermined temperature drop amount at a predetermined determination time, and the combustion section does not completely blow out, but the combustion is not performed. In some cases, it may be erroneously determined that complete blow-off has occurred in the part. Exhaust exhausted from the combustion section even when bumping occurs in the evaporation section where water suddenly evaporates in a short time, the pressure in the evaporation section suddenly increases, and partial blowout occurs temporarily. It is erroneously determined that a complete blow-off has occurred in the combustion section even though the gas temperature has fallen to a predetermined temperature drop amount or more during the predetermined determination time and no complete blow-out has occurred in the combustion section. It may be done.

  The present invention has been made to solve the above-described problems, and has an object to suppress misjudgment of complete blow-off in a combustion section where unused fuel from a fuel cell is burned in a fuel cell system. To do.

  The invention of the fuel cell system according to claim 1, which has been made to solve the above-described problems, includes an evaporation unit that evaporates supplied reformed water to generate water vapor, and water vapor generated in the evaporation unit. A reforming unit that generates fuel from a reforming raw material, a fuel cell that generates electricity using the fuel and oxidant gas generated by the reforming unit, and a combustible gas that includes the unused fuel from the fuel cell A first combustion part for heating the evaporation part and the reforming part by burning with an oxidant gas, and an unused combustible gas exhausted from the first combustion part is introduced, and the combustible gas is When the temperature of the second combustion unit to be burned, the temperature detection unit for detecting the temperature of the second combustion unit, and the temperature of the second combustion unit detected by the temperature detection unit are higher than the determination temperature, Combustion in the first combustion section stops In the case where there is no change that can cause a partial partial blow-off in the first combustion unit in any of the fuel cell and the evaporation unit, it is determined that complete blow-off has occurred. The determination temperature is set to a first determination temperature, and when the change occurs in at least one of the fuel cell and the evaporation unit, the determination temperature is set to a second determination temperature higher than the first determination temperature. A determination temperature setting unit.

  According to this, when a change in which at least one of the fuel cell and the evaporation unit may cause temporary partial blow-off occurs in the first combustion unit, the blow-off determination unit is higher than the first determination temperature. Based on the second determination temperature, the presence or absence of occurrence of complete blow-off in the first combustion portion is determined. If not, the blow-off determination portion determines whether complete blow-off in the first combustion portion is based on the first determination temperature. Determine if it occurs. For this reason, a temporary partial blowout occurs in the first combustion section, and the temperature of the second combustion section temporarily increases due to an increase in the amount of unused combustible gas introduced into the second combustion section. Even if it rises automatically, the blow-off determination unit can determine whether or not complete blow-off has occurred in the first combustion unit based on the second determination temperature that is higher than the first determination temperature. Therefore, it is possible to suppress erroneous determination that complete blow-out has occurred in the first combustion portion, even though complete blow-out has not occurred in the first combustion portion.

  The invention according to claim 2 is the invention according to claim 1, wherein the determination temperature setting unit is configured to detect the second combustion unit detected by the temperature detection unit when the second determination temperature is set. When the temperature of the first combustion temperature is lower than the first determination temperature, or a change that may cause a partial partial blow-off in the first combustion unit in either the fuel cell or the evaporation unit is the first If the predetermined time has not elapsed after the second determination temperature is set, the determination temperature is set to the first determination temperature. According to this, the second determination temperature does not remain set. For this reason, the determination temperature setting unit determines whether the first determination temperature and the first determination unit are based on whether at least one of the fuel cell and the evaporation unit has undergone a change that may cause temporary partial blowout in the first combustion unit. Either of the two judgment temperatures can be reset. Therefore, the presence or absence of occurrence of complete blow-off in the first combustion part is appropriately determined.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the power generation detection unit that detects the generated power or the generated current of the fuel cell, and the fuel cell detected by the power generation detection unit A first change determination unit that determines that the change that may cause partial partial blow-off in the first combustion unit has occurred in the fuel cell when a variation in generated power or generated current becomes greater than a determination threshold; Have. If the generated power or generated current in the fuel cell varies, the combustion state of the first fuel part becomes unstable along with it, so that a partial partial blow-off may occur in the first combustion part. The change determination unit determines that a change that may cause a partial partial blow-off in the first combustion unit has occurred in the fuel cell when a variation in the generated power or generated current of the fuel cell becomes greater than a determination threshold. For this reason, generation | occurrence | production of the temporary partial blow-off in the 1st combustion part resulting from the fluctuation | variation of the generated electric power of a fuel cell is detected reliably. Therefore, since an appropriate temperature is set as the determination temperature, the blow-off determination unit can appropriately determine whether or not complete blow-off has occurred in the first combustion unit.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, a bumping determination unit that determines whether or not bumping has occurred in the evaporation unit, and a bumping determination in the evaporation unit by the bumping determination unit. And a second change determination unit that determines that the change that may cause temporary partial blow-off in the first combustion unit has occurred in the evaporation unit when generation is determined. When bumping occurs in the evaporation section, the water vapor pressure in the evaporation section rises rapidly, so that the flow rate of the steam and reforming raw material supplied to the first combustion section rises temporarily, temporarily in the first combustion section. Partial blowout may occur. The change determination unit determines that a change that may cause a partial partial blow-off in the first combustion unit has occurred in the evaporation unit when the bumping determination unit determines the occurrence of bumping in the evaporation unit. For this reason, the occurrence of temporary partial blow-off in the first combustion portion due to the occurrence of bumping in the evaporation portion is reliably detected. Therefore, since an appropriate temperature is set as the determination temperature, the blow-off determination unit can appropriately determine whether or not complete blow-off has occurred in the first combustion unit.

  The invention according to claim 5 is the invention according to claim 4, wherein the pump for supplying the reforming raw material to the reforming section and the flow rate for detecting the flow rate of the reforming raw material to the reforming section. The reforming raw material that is driven by the pump and supplied to the reforming unit based on the flow rate of the reforming raw material detected by the detection unit and the flow rate detection unit to the reforming unit A pump control unit that feedback-controls the flow rate of the flow rate, and the bumping determination unit includes a flow rate of the reforming material detected by the flow rate detection unit to the reforming unit, an instruction flow rate to the pump, When the deviation exceeds the deviation threshold, it is determined that bumping has occurred in the evaporation section. According to this, when the deviation between the flow rate of the raw material for reforming to the reforming unit detected by the flow rate detection unit and the instruction flow rate to the pump exceeds the deviation threshold, the bumping determination unit performs bumping in the evaporation unit. Can be determined to have occurred. This is due to the following reason. When bumping occurs in the evaporation part, the water vapor pressure in the evaporation part rapidly increases and then decreases rapidly. This is because the back pressure on the downstream side of the evaporation section suddenly increases and decreases, and the flow rate of the reforming raw material supplied to the evaporation section also increases and decreases. Therefore, it is possible to reliably detect the occurrence of bumping in the evaporation unit.

  The invention according to claim 6 is the invention according to claim 4, wherein a pump for supplying the reforming raw material to the reforming section, and a flow rate for detecting a flow rate of the reforming raw material to the reforming section. The reforming raw material that is driven by the pump and supplied to the reforming unit based on the flow rate of the reforming raw material detected by the detection unit and the flow rate detection unit to the reforming unit A pump control unit that feedback-controls the flow rate of the evaporating unit when the change amount of a control command value commanded to the pump by the pump control unit exceeds a control command threshold value. It is determined that bumping has occurred. According to this, the bumping determination unit can determine that bumping has occurred in the evaporation unit when the change amount of the control command value commanded to the pump by the pump control unit exceeds the control command threshold. This is due to the following reason. When bumping occurs in the evaporation part, the water vapor pressure in the evaporation part rapidly increases and then decreases rapidly. Then, the back pressure on the downstream side of the evaporating section is abruptly increased or decreased, so that the control command value to the pump in which the flow rate of the reforming raw material is backed is changed. Therefore, it is possible to reliably detect the occurrence of bumping in the evaporation unit.

It is a schematic diagram showing an outline of one embodiment of a fuel cell system according to the present invention. It is a flowchart of the "first complete blow-off determination process" executed by the control device shown in FIG. It is a graph showing the relationship between time and the temperature T of a 2nd combustion part, and is a time chart when the "1st complete blow-off determination process" is performed. It is a flowchart of the "2nd complete blow-off determination process" performed with the control apparatus shown in FIG. It is a flowchart of the "third complete blow-off determination process" executed by the control device shown in FIG. It is a graph showing the relationship between time and the temperature T of a 2nd combustion part, and is a time chart when the "3rd complete blow-off determination process" is performed. It is a graph showing the relationship between time and the temperature T of a 2nd combustion part, and is a time chart when the "4th complete blow-off determination process" is performed.

  Hereinafter, an embodiment of the fuel cell system 100 according to the present invention will be described. As shown in FIG. 1, the fuel cell system 100 includes a power generation unit 10 and a hot water storage tank 21. The power generation unit 10 includes a housing 10a, a fuel cell module 11, a heat exchanger 12, an inverter device 13, a water tank 14, and a control device 15.

  The fuel cell module 11 includes a casing 31, an evaporation unit 32, a reforming unit 33, and a fuel cell 34. The casing 31 is formed in a box shape with a heat insulating material. The evaporation unit 32 is heated by combustion gas burned by a first combustion unit 36 to be described later, evaporates the supplied reforming water to generate water vapor, and preheats the supplied reforming raw material. It is. The evaporation section 32 mixes the steam generated in this way and the preheated reforming raw material and supplies the mixture to the reforming section 33.

  One end of a reforming material supply pipe 11a is connected to the evaporation section 32. A supply source Gs is connected to the other end of the reforming material supply pipe 11a. The supply source Gs supplies a raw material for reforming. As reforming raw materials, there are gas fuels for reforming such as natural gas and LP gas, and liquid fuels for reforming such as kerosene, gasoline and methanol. A fuel cell system 100 according to this embodiment will be described with respect to an embodiment using natural gas as a reforming raw material.

  The reforming material supply pipe 11a is provided with a shutoff valve 11a1, a desulfurizer 11a2, a flow rate sensor 11a3, a buffer tank 11a4, a pump 11a5, and a check valve 11a6 in order from the upstream. The shut-off valve 11a1 is a valve (double valve) that shuts off the reforming material supply pipe 11a in a freely openable / closable state according to a command from the control device 15. The desulfurizer 11a2 removes a sulfur content (for example, a sulfur compound) in the reforming raw material. The flow rate sensor 11 a 3 (flow rate detection unit) detects the flow rate of the reforming raw material supplied to the evaporation unit 32, that is, the flow rate per unit time, and transmits the detection result to the control device 15. . The buffer tank 11a4 suppresses a decrease in accuracy of the flow sensor 11a3 and a deviation from the true value due to the pulsation of the pump 11a5.

  The pump 11a5 is a supply device that supplies fuel (reforming raw material) to the fuel cell 34 by supplying the reforming raw material to the evaporation unit 32, and is supplied from the supply source Gs by a control command value from the control device 15. The fuel supply amount (supply flow rate (flow rate per unit time)) is adjusted. The pump 11a5 is a pumping device that sucks the reforming raw material and pumps it to the evaporation unit 32 (the reforming unit 33). Based on the flow rate of the reforming raw material to the evaporation unit 32 (reforming unit 33) detected by the flow sensor 11a3, the control device 15 supplies the reforming that the pump 11a5 supplies to the evaporation unit 32 (reforming unit 33). Feedback control of raw material flow rate. In addition, the control apparatus 15 adjusts the electric current amount supplied to the motor (not shown) which drives the pump 11a5 by linear current control. Here, the linear current control includes PWM control for changing the voltage duty ratio for driving the pump 11a5 and changing the effective current. The check valve 11a6 is disposed between the pump 11a5 and the fuel cell module 11 (evaporating part 32), and allows the flow from the pump 11a5 to the fuel cell module 11, but prohibits the flow in the opposite direction. Is.

  One end of a water supply pipe 11b is connected to the evaporation section 32. The other end of the water supply pipe 11b is connected to the water tank. The water supply pipe 11b is provided with a reforming water pump 11b1. With such a configuration, the reformed water is supplied from the water tank 14 to the evaporation unit 32. One end of a cathode air supply pipe 11 c is connected to the fuel cell 34. A cathode air blower 11c1 is connected to the other end of the cathode air supply pipe 11c. With such a configuration, cathode air is supplied to the fuel cell 34.

  The reforming unit 33 is heated by the combustion gas burned by the first combustion unit 36 described later and supplied with heat necessary for the steam reforming reaction, so that the mixed gas (reformation) supplied from the evaporation unit 32 is supplied. The reformed gas is generated and derived from the raw material (water vapor). The reforming unit 33 is filled with a catalyst (for example, Ru or Ni-based catalyst), and the mixed gas reacts with the catalyst to be reformed to generate a gas containing hydrogen gas and carbon monoxide. (So-called steam reforming reaction). The reformed gas contains hydrogen, carbon monoxide, carbon dioxide, steam, unreformed natural gas (methane gas), and reformed water (steam) that has not been used for reforming. As described above, the reforming unit 33 generates reformed gas (fuel) from the reforming raw material (raw fuel) and the reformed water and supplies the reformed gas (fuel) to the fuel cell 34. The steam reforming reaction is an endothermic reaction.

  The fuel cell 34 generates power using the fuel generated by the reforming unit 33 and cathode air (oxidant gas) supplied by the cathode air blower 11c1. The fuel cell 34 is configured by laminating a fuel electrode, an air electrode (oxidant electrode), and a plurality of cells 34a made of an electrolyte interposed between the two electrodes. The fuel cell of this embodiment is a solid oxide fuel cell, and uses zirconium oxide, which is a kind of solid oxide, as an electrolyte. Hydrogen, carbon monoxide, methane gas, etc. are supplied to the fuel electrode of the fuel cell 34 as fuel. The operating temperature is about 400-1000 ° C. Not only hydrogen but also natural gas and coal gas can be used directly as fuel. In this case, the reforming unit 33 can be omitted.

  On the fuel electrode side of the cell 34a, a fuel flow path 34b through which the reformed gas as the fuel flows is formed. An air flow path 34c through which air (cathode air) that is an oxidant gas flows is formed on the air electrode side of the cell 34a.

  The fuel cell 34 is provided on the manifold 35. The reformed gas from the reforming unit 33 is supplied to the manifold 35 via the reformed gas supply pipe 38. The lower end (one end) of the fuel flow path 34b is connected to the fuel outlet of the manifold 35, and the reformed gas led out from the fuel outlet is introduced from the lower end and led out from the upper end. . The cathode air sent out by the cathode air blower 11c1 is supplied via the cathode air supply pipe 11c, introduced from the lower end of the air flow path 34c, and led out from the upper end.

  The first combustion unit 36 is provided between the fuel cell 34, the evaporation unit 32, and the reforming unit 33. The first combustion unit 36 burns anode off-gas (fuel off-gas, combustible gas including unused fuel) from the fuel cell 34 and cathode off-gas (oxidant off-gas) from the fuel cell 34, and is generated after combustion. The evaporation section 32 and the reforming section 33 are heated by the combustion gas.

  In the first combustion section 36, the anode off gas is burned and a flame 37 is generated. The first combustion unit 36 is provided with a pair of ignition heaters 36a1 and 36a2 for igniting the anode off gas.

  The heat exchanger 12 is a device that is supplied with the combustion exhaust gas exhausted from the fuel cell module 11 and is supplied with hot water from the hot water storage tank 21 to exchange heat between the combustion exhaust gas and the hot water. The hot water storage tank 21 stores hot water, and is connected to a hot water circulation line 22 through which the hot water circulates (circulates in the direction of the arrow in FIG. 1). On the hot water circulation line 22, a circulation pump 22 a and a heat exchanger 12 are arranged in order from the lower end to the upper end of the hot water tank 21. The heat exchanger 12 is connected to a condensed water supply pipe 12 a connected to the water tank 14.

  In the heat exchanger 12, the combustion exhaust gas from the fuel cell module 11 is introduced into the heat exchanger 12 through the combustion exhaust gas introduction portion 12b, and is cooled by exchanging heat with hot water. Thereby, the water vapor contained in the exhaust gas is condensed to generate condensed water. The combustion exhaust gas after heat exchange passes through the exhaust pipe 12c, passes through the first exhaust port 10b provided in the housing 10a, and is discharged to the outside of the housing 10a. Moreover, the condensed condensed water is supplied to the water tank 14 through the condensed water supply pipe 12a. The water tank 14 purifies the condensed water with ion exchange resin.

  The heat exchanger 12, the hot water tank 21, and the hot water circulation line 22 described above constitute an exhaust heat recovery system 20. The exhaust heat recovery system 20 recovers and stores the exhaust heat of the fuel cell module 11 in hot water storage.

  A second combustion section 28 is provided at a portion where the inlet of the combustion exhaust gas introduction section 12 b of the heat exchanger 12 is connected to the casing 31, that is, at the outlet 31 a of the casing 31. The second combustion section 28 is a first combustion section off-gas which is a gas exhausted from the first combustion section 36, that is, an unused combustible gas (for example, hydrogen, methane gas, monoxide) exhausted from the first combustion section 36. Carbon etc.) is introduced and burned out. The 2nd combustion part 28 is comprised with the combustion catalyst which is a catalyst which burns combustible gas. Combustion catalysts include those in which a precious metal such as platinum or palladium is supported on a ceramic alone.

  Note that the combustion catalyst burns combustible gases such as hydrogen, methane gas, and carbon monoxide by the catalyst instead of flame combustion, so the combustion speed is high, a large amount of combustible gas can be burned, and the combustion efficiency is also high. Therefore, discharge of unburned gas can be suppressed.

  The second combustion section 28 is provided with a combustion catalyst heater 28a for heating the combustion catalyst to the catalyst activation temperature and burning the combustible gas. The combustion catalyst heater 28a is heated by an instruction from the control device 15, and is used to raise the combustion catalyst 28 to the activation temperature before the fuel cell system 100 is started. The second combustion section 28 is provided with a temperature sensor 28b (temperature detection section) for detecting the temperature T of the second combustion section 28. The detection result (output signal) of the temperature sensor 28 b is transmitted to the control device 15. Instead of the temperature sensor 28 b, a temperature sensor for detecting the temperature of the combustion exhaust gas discharged from the second combustion unit 28 may be provided at a position immediately downstream of the second combustion unit 28.

  A DC voltage output from the fuel cell 34 is input to the inverter device 13. The inverter device 13 converts the input DC voltage into a predetermined AC voltage and outputs the AC voltage to the power supply line 16b connected to the AC system power supply 16a and the external power load 16c (for example, an electrical appliance). An AC voltage from the system power supply 16a is input to the inverter device 13 through the power supply line 16b. The inverter device 13 converts the input AC voltage into a predetermined DC voltage and outputs it to an auxiliary machine (each pump, blower, etc.) or the control device 15. The control device 15 controls the operation of the fuel cell system 100 by driving an auxiliary machine. The inverter device 13 (generated power detection unit) detects the generated power of the fuel cell 34.

  The control device 15 performs overall control of the fuel cell system 100. The control device 15 adjusts the flow rate of the reforming raw material supplied to the evaporation unit 32 (reforming unit 33) by the pump 11a5, and the flow rate of the reforming water supplied to the evaporation unit 32 by the reforming water pump 11b1. Further, the generated power generated by the fuel cell 34 is adjusted by adjusting the flow rate of the cathode air supplied to the fuel cell 34 by the cathode air blower 11c1.

(First complete blow-off judgment process)
The “first complete blow-off determination process” will be described below using the flowchart shown in FIG. The “first complete blow-off determination process” shown in FIG. 2 changes the determination temperature for determining whether or not complete blow-off has occurred in the first combustion unit 36 due to fluctuations in the power generated by the fuel cell 34. It is an embodiment. When the fuel cell system is activated, the control device 15 advances the program to step S11.

  In step S11, the control device 15 (determination temperature setting unit) sets the first determination temperature T1, which is a determination temperature when the anode off-gas and the cathode off-gas are completely burned in the first combustion unit 36, and executes the program. Proceed to step S12. Note that complete combustion refers to a state in which a flame is formed in all of the first combustion portion 36. Further, the first determination temperature T1 is the first when the fluctuation of the generated power of the fuel cell 34 is equal to or less than the power determination threshold Pa, that is, when the partial blow-off in the first combustion unit 36 cannot occur. It is set to a temperature (for example, 350 ° C.) at which it can be detected that complete blow-off has occurred in the combustion unit 36. Here, the partial blow-off means a state in which the flame is not completely extinguished in the first combustion unit 36 (combustion is not stopped), but the flame is extinguished in a part of the first combustion unit 36.

  The reason for the occurrence of partial blowout will be described in detail below. If the generated power in the fuel cell 34 fluctuates, the first combustion is caused by the time lag between the change in the flow rate of the anode offgas supplied to the first combustion unit 36 and the change in the flow rate of the cathode offgas supplied to the first combustion unit 36. Temporary partial blowout may occur in the portion 36. Further, when the generated power in the fuel cell 34 varies, the water level of the reforming water changes in the evaporation unit 32 as the amount of heat supplied to the evaporation unit 32 by the first combustion unit 36 due to the change. As a result, bumping may occur in the evaporation section 32. Then, when bumping occurs in the evaporation unit 32, the water vapor pressure in the evaporation unit 32 rapidly increases, so the flow rates of the anode off-gas and cathode off-gas supplied to the first combustion unit 36 temporarily increase, Temporary partial blowout may occur in the first combustion section 36.

  Thus, when partial blowout occurs in the first combustion unit 36, the amount of combustible gas introduced from the first combustion unit 36 to the second combustion unit 28 increases. As a result, the temperature T of the second combustion unit 28 rises compared to before the partial blowout occurred. Thereafter, in the first combustion section 36, the flame that has once disappeared is restored by the flame that has not blown out. That is, the partial blow-off in the first combustion part 36 is eliminated, and the first combustion part 36 returns to the complete combustion state. It is also possible to reliably eliminate partial blow-off of the first combustion unit 36 by energizing the ignition heaters 36a1 and a2 based on the temperature of the second combustion unit 28 or the temperature of the first combustion unit 36. Is possible.

  Returning the description to the flowchart again. In step S12, when the control device 15 determines that the temperature T of the second combustion unit 28 detected by the temperature sensor 28b is higher than the first determination temperature T1 (step S12: YES), the program is set to step S13. Proceed. On the other hand, when it is determined that the temperature T is equal to or lower than the first determination temperature T1 (step S12: NO), the control device 15 repeats the process of step S12.

  In step S13, the control device 15 (first change determination unit) is based on a signal from the inverter device 13 during a time that is traced back in the past by a specified time Tm1 (for example, 20 to 30 minutes) from the time of determination in step S13. If it is determined that there has been a change in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa (step S13: YES), the program proceeds to step S14. On the other hand, based on the signal from the inverter device 13, the control device 15 determines the generated power of the fuel cell 34 that is greater than the power determination threshold Pa during a time that is traced back by the specified time Tm1 from the time of determination in step S 13. If it is determined that there is no change (step S13: NO), the program proceeds to step S16. Note that the power determination threshold Pa is set to a fluctuation amount of the generated power that may cause partial blowout in the first combustion unit 36. The specified time Tm1 is determined when the fluctuation of the generated power of the fuel cell 34 is greater than the power determination threshold Pa, that is, when partial blowout occurs in the first combustion unit 36. Is set to a time during which the temperature T can be higher than the first determination temperature T1.

  In step S14, the control device 15 (determination temperature setting unit) sets a second determination temperature T2 that is a determination temperature when partial blowout or complete blowout has occurred in the first combustion unit 36, and the program Advances to step S15. The second determination temperature T2 is set to a temperature at which it is possible to detect that complete blow-off has occurred in the first combustion unit 36 when the variation in the generated power of the fuel cell 34 is greater than the power determination threshold Pa. The second determination temperature T2 is set to a temperature at which the temperature T of the second combustion section 28 does not exceed the second determination temperature T2 when partial blow-off occurs in the first combustion section 36. Further, the second determination temperature T2 is a temperature lower than the heat resistance temperature of the catalyst of the second combustion section 28, the heat resistance temperature of peripheral parts (for example, gaskets) of the second combustion section 28, and the heat resistance temperature of the heat exchanger 12 (for example, 400). ~ 500 ° C).

  Thus, the temperature T of the second combustion section 28 becomes higher than the first determination temperature T1 (determined as YES in step S12), and during the time that goes back in the past by the specified time Tm1 from the determination in step S13, When there is a fluctuation in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa (YES in step S13), it is determined whether or not complete blowout has occurred in the first combustion unit 36. The determination temperature is changed to the second determination temperature T2 (step S14).

  On the other hand, if there is no change in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa during the time that is traced back by the specified time Tm1 from the time of determination in step S13 (determined NO in step S13). The determination temperature for determining whether or not complete blowout has occurred in the first combustion unit 36 is maintained at the first determination temperature T1.

  In addition, when the second determination temperature T2 is set and the temperature T of the second combustion unit 28 is lower than the first determination temperature T1, the temperature T of the second combustion unit 28 is determined as the second determination. Since it is lower than the temperature T2 (determined as NO in step S15), the first determination temperature T1 is set (step S11), and the set first determination temperature is maintained (determined as NO in step S12). That is, when the second determination temperature T2 is set and the temperature T of the second combustion unit 28 is lower than the first determination temperature T1, the first determination temperature T1 is set.

Returning to the flowchart shown in FIG.
In step S15, when the control device 15 determines that the temperature T of the second combustion unit 28 detected by the temperature sensor 28b is higher than the second determination temperature T2 (step S15: YES), the program is transferred to step S16. Proceed. On the other hand, when determining that the temperature T is equal to or lower than the second determination temperature T2 (step S15: NO), the control device 15 returns the program to step S11.

  In step S <b> 16, the control device 15 (blow-off determination unit) determines that complete blow-off has occurred in the first combustion unit 36. A factor that causes complete blow-off in the first combustion section 36 includes failure of the supply system for reforming raw material and reforming water. As described above, even when the temperature T of the second combustion unit 28 becomes higher than the first determination temperature T1 (determined as YES in step S12), during the time that is traced back to the past by the specified time Tm1 from the determination in step S13. In step S14, when the variation in the generated power of the fuel cell 34 is larger than the power determination threshold Pa (determined as YES in step S13), that is, if partial blowout may occur in the first combustion unit 36, A second determination temperature T2 is set. If the temperature T of the second combustion section 28 does not exceed the second determination temperature T2, it is not determined in step S16 that complete blowout has occurred in the first combustion section 36. The control device 15 advances the program to step S17.

  In step S17, the control device 15 stops driving the pump 11a5, the reforming water pump 11b1, and the cathode air blower 11c1, and supplies the reforming raw material, reforming water, and cathode air to the fuel cell 34. Execute stop operation processing to stop. When step S17 ends, the “first complete blow-off determination process” ends.

(Explanation of time chart)
Hereinafter, a case where partial blow-off occurs and a case where complete blow-off occurs will be described with reference to a time chart shown in FIG. During the operation of the fuel cell system 100, at time t1, a fluctuation in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa occurs, and a partial blowout or a complete blowout occurs in the first combustion unit 36. The temperature T of the combustion unit 28 rises, and at time t2, the temperature T exceeds the first determination temperature T1. Then, since the fluctuation of the generated power of the fuel cell 34 that is larger than the power determination threshold Pa occurs during a time traced back by the specified time Tm1 from the time t2 (determined as YES in step S13 in FIG. 2), At time t2, the second determination temperature T2 is set (step S14). When partial blowout has occurred in the first combustion section 36, the temperature T of the second combustion section 28 does not exceed the second determination temperature T2 (solid line shown between time t2 and time t4). , NO is determined in step S15), it is not determined that complete blow-off has occurred in the first combustion section 36. As described above, when a variation in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa occurs, the determination temperature for determining whether or not complete blowout has occurred in the first combustion unit 36 is the first determination. The temperature is changed from the temperature T1 to the second determination temperature T2. In this case, when the first combustion unit 36 is not completely blown out but partially blown out, the temperature T of the second combustion unit 28 does not exceed the second determination temperature T2. For this reason, it is not erroneously determined that complete blow-off has occurred in the first combustion section 36, even though complete blow-out has not occurred in the first combustion section 36.

  After the occurrence of partial blow-off in the first combustion unit 36, the flame that has once disappeared is revived by the flame that has not blown out in the first combustion unit 36. Then, since the amount of combustible gas contained in the first combustion part off-gas introduced into the second combustion part 28 decreases, the temperature T of the second combustion part 28 decreases, and at time t4, the temperature T is first determined. When the temperature is equal to or lower than the temperature T1, the first determination temperature T1 is set (step S11).

  On the other hand, during the operation of the fuel cell system 100, when the generated power fluctuation of the fuel cell 34 that is larger than the power determination threshold Pa occurs at time t1, and complete blowout has occurred in the first combustion unit 36. 3, at time t3, the temperature T of the second combustion unit 28 exceeds the second determination temperature T2 (determined as YES in step S15), and complete blowout occurs in the first combustion unit 36. It is determined that it has been done (step S16).

  Further, during the operation of the fuel cell system 100, when the temperature T exceeds the first determination temperature T1 at t2 without causing fluctuations in the generated power of the fuel cell 34 that is greater than the electricity determination threshold Pa (YES in step S12). And NO is determined in step S13), and it is determined that complete blow-off has occurred in the first combustion section 36 (step S16). Thus, it is determined whether or not the complete blow-off has occurred in the first combustion unit 36 at the first determination temperature T1 that is lower than the second determination temperature T2. For this reason, the occurrence of complete blow-off in the first combustion unit 36 is determined earlier.

(Effect of this embodiment)
As is apparent from the above description, the control device 15 (determination temperature setting unit) determines that the fuel cell 34 does not change when the first combustion unit 36 does not undergo a change that may cause temporary partial blowout. One determination temperature T1 is set (step S11 in FIG. 2). On the other hand, the control device 15 (determination temperature setting unit) is higher than the first determination temperature T1 when the fuel cell 34 undergoes a change that may cause temporary partial blowout in the first combustion unit 36. A second determination temperature T2 is set (step S14 in FIG. 2). According to this, when the fuel cell 34 undergoes a change that may cause a partial partial blow-off in the first combustion unit 36, the control device 15 (blow-out determination unit) starts from the first determination temperature T <b> 1. On the basis of the higher second determination temperature T2, the presence or absence of occurrence of complete blow-off in the first combustion unit 36 is determined (step S15 in FIG. 2). If not, the control device 15 (blow-out determination unit) Based on the first determination temperature T1, the presence or absence of occurrence of complete blow-off in the first combustion section 36 is determined (step S12 and step S13 in FIG. 2).

  For this reason, a partial partial blow-off occurs in the first combustion unit 36, and the amount of unused combustible gas introduced into the second combustion unit 28 increases. Even when the temperature rises temporarily (shown by a solid line between time t2 and time t4 in FIG. 3), the control device 15 (blow-out determination unit) determines the first in step S15 in FIG. Based on the second determination temperature T2 higher than the determination temperature T1, it is possible to determine whether or not the complete blow-off has occurred in the first combustion unit 36. Therefore, it is possible to suppress erroneous determination that complete blow-out has occurred in the first combustion unit 36 even though complete blow-out has not occurred in the first combustion unit 36.

  In the control device 15 (determination temperature setting unit), when the second determination temperature T2 is set, the temperature T of the second combustion unit 28 detected by the temperature sensor 28b is lower than the first determination temperature T1. If it is determined (NO in steps S15 and S12 in FIG. 2), the first determination temperature T1 is set (step S11). As a result, the second determination temperature T2 does not remain set. For this reason, one of the first determination temperature and the second determination temperature is reset based on whether or not the fuel cell 34 has undergone a change that may cause a temporary partial blow-off in the first combustion unit 36. . Therefore, the presence or absence of occurrence of complete blow-off in the first combustion unit 36 is appropriately determined.

  If the generated power in the fuel cell 34 fluctuates, the first combustion is caused by the time lag between the change in the flow rate of the anode offgas supplied to the first combustion unit 36 and the change in the flow rate of the cathode offgas supplied to the first combustion unit 36. Temporary partial blowout may occur in the portion 36. Further, when the generated power in the fuel cell 34 varies, the water level of the reforming water changes in the evaporation unit 32 as the amount of heat supplied to the evaporation unit 32 by the first combustion unit 36 due to the change. As a result, bumping may occur in the evaporation section 32. Then, when bumping occurs in the evaporation unit 32, the water vapor pressure in the evaporation unit 32 rapidly increases, so the flow rates of the anode off-gas and cathode off-gas supplied to the first combustion unit 36 temporarily increase, Temporary partial blowout may occur in the first combustion section 36. Using this principle, in step S13 of FIG. 2, the control device 15 (first change determination unit) converts the change in the fuel cell 34 that may cause temporary partial blowout in the first combustion unit 36 into an inverter. The detection is performed based on whether or not the fluctuation of the generated power of the fuel cell 34 detected by the device 13 (power generation detection unit) is larger than the power determination threshold Pa. As a result, the occurrence of temporary partial blow-off in the first combustion section 36 due to fluctuations in the power generated by the fuel cell 34 is reliably detected.

  The second combustion section 28, which is a combustion catalyst, has good temperature responsiveness with respect to the amount of unused combustible gas. On the other hand, since the first combustion unit 36 has a large heat capacity, the response speed of the temperature drop of the exhaust gas exhausted from the first combustion unit 36 is slow when complete blowout occurs in the first combustion unit 36. In the present embodiment, since the presence or absence of complete blow-off in the first combustion unit 36 is determined based on the temperature T of the second combustion unit 28 that is a combustion catalyst, the exhaust gas exhausted from the first combustion unit 36 Compared with the embodiment in which the presence / absence of complete blow-out in the first combustion unit 36 is determined based on the temperature of the first combustion unit 36, the presence / absence of complete blow-out in the first combustion unit 36 can be determined with good response.

  In the “first complete blow-off determination process” shown in FIG. 2, when the temperature T of the second combustion unit 28 becomes higher than the first determination temperature T <b> 1 in step S <b> 12, the controller 15 performs step in step S <b> 13. A determination is made as to whether or not there has been a change in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa during a time that has been traced back by the specified time Tm1 from the determination in S13, and the second determination temperature T2 is set. Judging whether to do. Thereby, the control device 15 always determines whether or not there is a variation in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa, and determines whether or not to set the second determination temperature T2. Compared with, the processing executed by the control device 15 is light and the storage area of the control device 15 is not occupied.

(Second embodiment)
In the second embodiment in which the control device 15 executes the “second complete blow-off determination process” using the flowchart shown in FIG. 4, the “first complete blow-off” shown in FIG. Differences from the embodiment (first embodiment) in which the “determination process” is executed will be described. Regarding the “second complete blow-off determination process”, the same step number as the flowchart shown in FIG. 2 is attached to the same process as the “first complete blow-off determination process” in the flowchart shown in FIG. The description is omitted. The “second complete blow-off determination process” is an embodiment in which a determination temperature for determining whether or not complete blow-off has occurred in the first combustion unit 36 is changed depending on whether or not bumping has occurred in the evaporation unit 32 ( Second embodiment). When bumping occurs in the evaporation unit 32 and the back pressure on the downstream side of the evaporation unit 32 increases or decreases, the fuel supplied to the first combustion unit 36 becomes a steam-rich state (reforming raw material lean state). In the evaporation section 32, the steam lean state (reforming raw material rich state) may occur, and partial blowout may occur in the first combustion section 36.

  In step S12, when the control device 15 determines that the temperature T of the second combustion unit 28 detected by the temperature sensor 28b is higher than the first determination temperature T1 (step S12: YES), the program is transferred to step S21. Proceed.

  In step S21, the control device 15 (second change determination unit) caused bumping in the evaporation unit 32 during a time that was traced back by a specified time Tm2 (for example, 20 to 30 minutes) from the time of determination in step S21. (Step S21: YES), the program proceeds to step S14. On the other hand, if the control device 15 determines that bumping has not occurred in the evaporation section 32 during the time traced back by the specified time Tm2 from the time of determination in step S21 (step S21: NO), The program proceeds to step S16. The specified time Tm2 is set so that the temperature T of the second combustion unit 28 is the first determination temperature T1 when bumping occurs in the evaporation unit 32, that is, when partial blowout may occur in the first combustion unit 36. It is set to a time that can be higher. Specifically, the control device 15 determines that bumping has occurred in the evaporation unit 32 when it is determined that either of the following (Condition 1) and (Condition 2) is satisfied.

(Condition 1) | ΔQ | ≧ ΔQa
ΔQ: Deviation between the flow rate of the reforming material detected by the flow sensor 11a3 and the commanded flow rate of the reforming material that the control device 15 instructs the pump 11a5 ΔQa: Deviation threshold value

  When bumping occurs in the evaporation unit 32, the amount of water vapor instantaneously increases in the evaporation unit 32, the back pressure on the downstream side of the evaporation unit 32 increases, and then the back pressure on the downstream side of the evaporation unit 32 decreases due to the reaction. To do. Then, the flow rate of the reforming raw material detected by the flow sensor 11a3 and the instruction flow rate of the reforming raw material that the control device 15 instructs to the pump 11a5 by feedback control are different. Using this principle, when Condition 1 is satisfied, it is determined that bumping has occurred in the evaporation section 32.

(Condition 2) | Δm | ≧ Δma
Δm: change amount of duty ratio (control command value) of current supplied from the control device 15 to the motor driving the pump 11a5 Δma: specified duty threshold value (control command threshold value)

  When bumping occurs in the evaporation unit 32, the back pressure on the downstream side of the evaporation unit 32 increases, and then the back pressure on the downstream side of the evaporation unit 32 decreases due to the reaction, and the flow rate of the reforming raw material discharged by the pump 11a5. Increases or decreases. The control device 15 changes the duty ratio of the current supplied to the motor of the pump 11a5 by feedback control in order to set the flow rate of the reforming raw material discharged from the pump 11a5 to a state before the occurrence of bumping. Using this principle, when Condition 2 is satisfied, it is determined that bumping has occurred in the evaporation section 32.

  Thus, even if the temperature T of the second combustion unit 28 becomes higher than the first determination temperature T1 (determined as YES in step S12 in FIG. 4), the process goes back to the past by the specified time Tm2 from the determination in step S21. If bumping has occurred in the evaporation section 32 during the time (YES in step S21 in FIG. 4), that is, if partial blowout can occur in the first combustion section 36, step S14 in FIG. , The second determination temperature T2 is set. If the temperature T of the second combustion section 28 does not exceed the second determination temperature T2 (determined as YES in step S15 in FIG. 4), complete blow-off occurs in the first combustion section 36 in step S16 in FIG. It is not determined that

(Effect of the second embodiment)
As described above, when bumping occurs in the evaporation section 32, the water vapor pressure in the evaporation section 32 rapidly increases, so the flow rates of the anode off-gas and cathode off-gas supplied to the first combustion section 36 temporarily increase. Thus, a temporary partial blow-off may occur in the first combustion unit 36. Using this principle, in step S23 of FIG. 2, the control device 15 (second change determination unit) evaporates the change of the evaporation unit 32 in which the partial partial blow-off in the first combustion unit 36 may occur. It is detected by whether or not bumping has occurred in the part 32. As a result, the occurrence of temporary partial blow-off in the first combustion unit 36 due to the occurrence of bumping in the evaporation unit 32 is reliably detected.

  As described above, when bumping occurs in the evaporation unit 32, the water vapor pressure in the evaporation unit 32 rapidly increases and then decreases rapidly. Then, since the back pressure on the downstream side of the evaporation unit 32 rapidly increases and decreases, the flow rate of the reforming raw material supplied to the evaporation unit 32 also increases and decreases. Using this principle, in step S23 of FIG. 4, the control device 15 (sudden boiling determination unit) controls the control device 15 by the flow rate of the reforming raw material detected by the flow rate sensor 11a3 (flow rate detection unit) and feedback control. When the deviation ΔQ from the instruction flow rate of the reforming raw material instructed to the pump 11a5 exceeds the deviation threshold value ΔQa, it is determined that bumping has occurred in the evaporation section 32 (determined as YES in step S23 of FIG. 4). . Thereby, generation | occurrence | production of bumping in the evaporation part 32 is reliably detectable.

  As described above, when bumping occurs in the evaporation unit 32, the water vapor pressure in the evaporation unit 32 rapidly increases and then decreases rapidly. Then, the back pressure on the downstream side of the evaporation section 32 increases and decreases rapidly, so the duty ratio of the current supplied to the motor that drives the pump 11a5 in which the flow rate of the reforming raw material is backed (control command for the pump 11a5) Value) changes. Using this principle, in step S23 of FIG. 4, the control device 15 (sudden boiling determination unit) determines that the amount of change in the duty ratio of the current supplied to the motor that drives the pump 11a5 is the specified duty threshold Δma (control command threshold value). ) Is exceeded, it is determined that bumping has occurred in the evaporation section 32 (YES in step S23 of FIG. 4). Thereby, generation | occurrence | production of bumping in the evaporation part 32 is reliably detectable.

  In the “second complete blow-off determination process” shown in FIG. 4, when the temperature T of the second combustion unit 28 becomes higher than the first determination temperature T1 in step S12, in step S21, the control device 15 performs step It is determined whether the second determination temperature T2 is set by determining whether bumping has occurred in the evaporating section 32 during the time that has been traced back in the past by the specified time Tm2 from the determination of S21. . Thereby, compared with the embodiment in which the control device 15 always determines whether or not bumping has occurred in the evaporation section 32 and determines whether or not to set the second determination temperature T2, the control device 15 The processing to be executed is light and the storage area of the control device 15 is not occupied.

  There may be an embodiment in which both the “first complete blow-off determination process” shown in FIG. 2 and the “second complete blow-off determination process” shown in FIG. 4 described above are executed. Further, there may be an embodiment in which only one of the “first complete blow-off determination process” and the “second complete blow-off determination process” is executed.

(Third embodiment)
Hereinafter, a third embodiment in which the control device 15 executes the “third complete blow-off determination process” will be described using the flowchart shown in FIG. 5. In the “first complete blow-off determination process”, after the temperature T of the second combustion unit 28 exceeds the first determination temperature T1 (YES in step S12 in FIG. 2), the specified time Tm1 from the determination in step S13. When there is a fluctuation in the generated power of the fuel cell 34 that is larger than the power determination threshold Pa during a time that is traced back in the past (determined as YES in step S13), the second determination temperature T2 is set (step S13). S14). On the other hand, in the “third complete blow-off determination process”, when the variation in the generated power of the fuel cell 34 is larger than the power determination threshold Pa, the second determination temperature T2 is set, and the variation in the generated power of the fuel cell 34 is determined. Is equal to or less than the power determination threshold Pa, the first determination temperature T1 is set. This will be described in detail below.

When the fuel cell system 100 is activated, the program proceeds to step S111.
In step S111, when the control device 15 determines that the fluctuation of the generated power of the fuel cell 34 is larger than the power determination threshold Pa based on the signal from the inverter device 13 (step S111: YES), the program is executed. Proceed to step S113. On the other hand, when the control device 15 determines that the variation in the generated power of the fuel cell 34 is equal to or less than the power determination threshold Pa (step S111: NO), the control device 15 advances the program to step S112.

In step S112, the control device 15 (determination temperature setting unit) sets the first determination temperature T1, and advances the program to step S121.
In step S113, the control device 15 (determination temperature setting unit) sets the second determination temperature T2, and advances the program to step S131.
Thus, when the fluctuation | variation of the electric power generation of the fuel cell 34 is larger than the electric power determination threshold value Pa, 2nd determination temperature T2 is set. On the other hand, when the fluctuation of the generated power of the fuel cell 34 is equal to or less than the power determination threshold Pa, the first determination temperature T1 is set.

  In step S121, when the control device 15 determines that the temperature T of the second combustion unit 28 detected by the temperature sensor 28b is higher than the first determination temperature T1 (step S121: YES), the program is transferred to step S122. Proceed. On the other hand, when the control device 15 determines that the temperature T is equal to or lower than the first determination temperature T1 (step S121: NO), the control device 15 returns the program to step S111.

  In step S122, the control device 15 determines that complete blow-off has occurred in the first combustion section 36, and advances the program to step S123.

  In step S123, the control device 15 executes the stop operation process described above. When step S123 ends, the “third complete blow-off determination process” shown in FIG. 5 ends.

  In step S131, when the control device 15 determines that the temperature T of the second combustion unit 28 detected by the temperature sensor 28b is higher than the second determination temperature T2 (step S131: YES), the program is transferred to step S122. Proceed. On the other hand, when the control device 15 determines that the temperature T is equal to or lower than the second determination temperature T2 (step S131: NO), the control device 15 advances the program to step S132.

  As described above, when the variation in the generated power of the fuel cell 34 is larger than the power determination threshold Pa (YES in step S111), that is, when partial blow-off can occur in the first combustion unit 36, in S113. Second determination temperature T2 is set. If the temperature T of the second combustion section 28 does not exceed the second determination temperature T2, it is not determined in step S122 that complete blow-off has occurred in the first combustion section 36.

  In step S132, when it is determined that the specified time Tm3 has elapsed since the second determination temperature T2 was set in step S113 (step S132: YES), the control device 15 returns the program to step S111. On the other hand, when it is determined that the specified time Tm3 has not elapsed since the second determination temperature T2 was set in step S113 (step S132: NO), the control device 15 returns the program to step S131. Note that the specified time Tm3 rises due to the partial blow-off when the fluctuation of the generated power of the fuel cell 34 becomes larger than the power determination threshold Pa and the partial blow-off occurs in the first combustion unit 36. The temperature T of the second combustion section 28 is set to a time (for example, 20 to 30 minutes) for returning to the temperature before partial blowout occurs.

(Explanation of the time chart when the third complete blow-off determination process is executed)
Hereinafter, the case where the partial blow-off occurs and the case where the complete blow-off occurs when the “third complete blow-off determination process” is executed will be described with reference to the time chart shown in FIG. 6. During the operation of the fuel cell system 100, when a change in the generated power of the fuel cell 34 greater than the power determination threshold Pa occurs at time t1, the second determination temperature T2 is set (step S113 in FIG. 5). As the generated power of the fuel cell 34 is greater than the power determination threshold Pa, partial blowout or complete blowout occurs in the first combustion section 36, and the temperature T of the second combustion section 28 rises. When partial blow-off has occurred in the first combustion section 36, the temperature T of the second combustion section 28 does not exceed the second determination temperature T2 (solid line shown between time t1 and time t3, step In S131, NO is determined), and it is not determined that complete blow-off has occurred in the first combustion section 36.

  At time t3, when the specified time Tm3 has elapsed since the second determination degree T2 was set (YES in step S132), and the generated power fluctuation of the fuel cell 34 greater than the power determination threshold Pa has not occurred. (Determined NO in step S111), the first determination temperature T1 is set (step S112).

  On the other hand, during the operation of the fuel cell system 100, when the generated power fluctuation of the fuel cell 34 that is larger than the power determination threshold Pa occurs at time t1, and complete blowout has occurred in the first combustion unit 36. 6, at time t2, the temperature T of the second combustion section 28 exceeds the second determination temperature T2 (determined as YES in step S131), and complete blowout occurs in the first combustion section 36. It is determined that it has been done (step S122).

  In the “third complete blow-off determination process”, the second determination temperature T2 is set without a time lag when the variation in the generated power of the fuel cell 34 is greater than the power determination threshold Pa. As a result, when partial blowout occurs in the first combustion section 36 and the temperature T of the second combustion section 28 rises gently, it is erroneously determined that complete blowout has occurred in the first combustion section 36. It is suppressed. In other words, there is a fluctuation in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa during a time that goes back in the past by the specified time Tm1 after the temperature T of the second combustion unit 28 exceeds the first determination temperature T1. In the case where the second determination temperature T2 is set in this case, the following erroneous determination can occur. When partial blowout occurs in the first combustion section 36 and the temperature T of the second combustion section 28 rises gently, the temperature of the generated power of the fuel cell 34 that is greater than the power determination threshold Pa is generated. If T exceeds the first determination temperature T1 for a time longer than the specified time Tm1, the first determination temperature T1 is not changed to the second determination temperature T2, and it is erroneously determined that complete blowout has occurred in the first combustion section 36. It will be.

(Fourth embodiment)
Hereinafter, the fourth embodiment in which the control device 15 executes the “fourth complete blow-off determination process” will be described with reference to the flowchart shown in FIG. 7. Differences from the embodiment (third embodiment) that executes the “determination process” will be described. Regarding the “fourth complete blow-off determination process”, the same step number as the flowchart shown in FIG. 5 is attached to the same process as the “third complete blow-off determination process” in the flowchart shown in FIG. The description is omitted.

  In the “fourth complete blow-off determination process” shown in FIG. 7, in step S <b> 111, the control device 15 determines whether bumping has occurred in the evaporation unit 32 as in the process of step S <b> 21 in FIG. 4. One of the first determination temperature T1 and the second determination temperature T2 is set according to the determination result. That is, if the controller 15 (second change determination unit) determines in step S111 that bumping has occurred in the evaporation unit 32 (step S111: YES), the program proceeds to step S112. On the other hand, if the control device 15 determines that bumping has not occurred in the evaporation section 32 (step S111: NO), the control device 15 advances the program to step S112.

  There may be an embodiment in which both the “third complete blow-off determination process” shown in FIG. 5 and the “fourth complete blow-off determination process” shown in FIG. 7 described above are executed. Further, there may be an embodiment in which only one of the “third complete blow-off determination process” and the “fourth complete blow-off determination process” is executed.

(Another embodiment)
In the “first complete blow-off determination process” described above, in step S13 of FIG. 2, the control device 15 (first change determination unit) performs a time period that is traced back by the specified time Tm1 from the determination in step S13. When it is determined that there has been a change in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa, the program proceeds to step S14. However, even if the control device 15 causes the program to proceed to step S14 in FIG. 2 when fluctuations in the generated power of the fuel cell 34 greater than the power determination threshold Pa occur more than the specified number of times within the specified time. There is no problem.

  In the “first complete blow-off determination process” and the “third complete blow-off determination process” described above, the control device 15 is based on the signal from the inverter device 13 in step S13 of FIG. 2 or step S111 of FIG. Thus, the fluctuation amount of the generated power in the fuel cell 34 is acquired. However, an embodiment in which the fluctuation amount of the generated power in the fuel cell 34 is calculated based on the sweep current from the inverter device 13 and the flow rate of the reformed gas or cathode air supplied to the fuel cell 34 may be used. No.

  In the embodiment described above, in step S13, the control device 15 (first change determination unit) is based on the signal from the inverter device 13 during the time that has been traced back by the specified time Tm1 from the time of determination in step S13. In FIG. 5, it is determined whether or not there is a variation in the generated power of the fuel cell 34 that is greater than the power determination threshold Pa. However, the control device 15 (first change determination unit) determines that the fuel is larger than the current determination threshold value Pb during the time that is traced back by the specified time Tm1 from the time of determination in step S13 based on the signal from the inverter device 13. Even in an embodiment in which it is determined whether or not there is a fluctuation in the generated current of the battery 34, there is no problem. In the case of this embodiment, the inverter device 13 detects the generated current of the fuel cell 34. Then, based on the signal from the inverter device 13, the control device 15 (first change determination unit) has a fuel larger than the current determination threshold value Pb during a time that is traced back by the specified time Tm1 from the time of determination in step S13. If it is determined that the generated current fluctuation of the battery 34 has occurred (step S13: YES), the program proceeds to step S14. On the other hand, on the basis of the signal from the inverter device 13, the control device 15 determines the generated current of the fuel cell 34 that is larger than the current determination threshold value Pb during the time that is traced back by the specified time Tm1 from the time of determination in step S 13. If it is determined that there is no change (step S13: NO), the program proceeds to step S16. The current determination threshold value Pb is set to the amount of fluctuation in the generated current that can cause partial blowout in the first combustion unit 36.

  DESCRIPTION OF SYMBOLS 11a3 ... Flow rate sensor (flow rate detection part), 11a5 ... Pump, 13 ... Inverter apparatus (power generation detection part), 15 ... Control apparatus (Blow-off determination part, determination temperature setting part, 1st change determination part, 2nd change determination part) , Bump boiling determination unit, pump control unit), 28 ... second combustion unit, 28b ... temperature sensor (temperature detection unit), 32 ... evaporation unit, 33 ... reforming unit, 34 ... fuel cell, 36 ... first combustion unit, 100: Fuel cell system.

Claims (6)

An evaporation section for evaporating the supplied reformed water to generate water vapor;
A reforming section for generating fuel from the steam generated in the evaporation section and a reforming raw material;
A fuel cell that generates electric power from the fuel and oxidant gas generated by the reforming unit;
A first combustion section for introducing a combustible gas containing the unused fuel from the fuel cell and burning it with an oxidant gas to heat the evaporation section and the reforming section;
Unused combustible gas exhausted from the first combustion section is introduced, the second combustion section for burning the combustible gas;
A temperature detection unit for detecting the temperature of the second combustion unit;
When the temperature of the second combustion unit detected by the temperature detection unit is higher than the determination temperature, the blow-off determination unit determines that a complete blow-off has occurred in which combustion has stopped in the first combustion unit. When,
If neither the fuel cell nor the evaporation unit undergoes a change that may cause temporary partial blowout in the first combustion unit, the determination temperature is set to the first determination temperature, and the fuel cell When the change occurs in at least one of the evaporation units, a determination temperature setting unit that sets the determination temperature to a second determination temperature that is higher than the first determination temperature;
A fuel cell system. The determination temperature setting unit includes:
In the case where the second determination temperature is set,
When the temperature of the second combustion unit detected by the temperature detection unit is lower than the first determination temperature, or
A change that may cause temporary partial blow-off in the first combustion section in both the fuel cell and the evaporation section has not occurred after a specified time has elapsed since the second determination temperature was set In
The fuel cell system according to claim 1, wherein the determination temperature is set to the first determination temperature. A power generation detection unit for detecting generated power or generated current of the fuel cell;
When the variation in the generated power or generated current of the fuel cell detected by the power generation detection unit becomes larger than a determination threshold, the change that may cause partial partial blow-off in the first combustion unit is the fuel. A first change determination unit that determines that the battery has occurred;
The fuel cell system according to claim 1 or 2, comprising: A bumping determination unit for determining whether bumping has occurred in the evaporation unit;
A second change for determining that the change that may cause a partial partial blow-off in the first combustion unit has occurred in the evaporation unit when the bumping determination unit determines the occurrence of bumping in the evaporation unit. A determination unit;
The fuel cell system according to claim 1 or 2, comprising: A pump for supplying the reforming raw material to the reforming section;
A flow rate detection unit for detecting a flow rate of the reforming raw material to the reforming unit;
Based on the flow rate of the reforming raw material detected by the flow rate detection unit to the reforming unit, the pump is driven to feed back the flow rate of the reforming raw material that the pump supplies to the evaporation unit. A pump control unit,
When the deviation between the flow rate of the reforming raw material detected by the flow rate detection unit to the reforming unit and the indicated flow rate to the pump exceeds a deviation threshold, the bumping determination unit The fuel cell system according to claim 4, wherein it is determined that bumping has occurred. A pump for supplying the reforming raw material to the reforming section;
A flow rate detection unit for detecting a flow rate of the reforming raw material to the steam reforming unit;
Based on the flow rate of the reforming material detected by the flow rate detection unit to the reforming unit, the pump is driven to feed back the flow rate of the reforming material that the pump supplies to the reforming unit. A pump control unit for controlling,
The fuel according to claim 4, wherein the bumping determination unit determines that bumping has occurred in the evaporation unit when a change amount of a control command value commanded to the pump by the pump control unit exceeds a control command threshold. Battery system.

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