JP2011060586A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system advantageous in carrying out a flooding control even at an extended power generation operation at a low output. <P>SOLUTION: The fuel cell system includes a fuel cell 1, an anode gas supply system 2 to supply anode gas to an anode electrode 10 of the fuel cell 1, a cathode gas supply system 5 to supply cathode gas to a cathode electrode 11 of the fuel cell 1, and a control portion 700 to control the anode gas supply system 2 and the cathode gas supply system 5. When continuous run time of a low-output power generation operation which tends to generate flooding elapses a first predetermined time t1, while the power generation operation is done in a way that the decline of an anode gas utilization factor in the fuel cell 1 is controlled, a first control to execute a flooding control power generation treatment for a second predetermined time t2 (t1>t2) is carried out by the control portion 700. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel cell system in which flooding may occur due to low power generation operation.

  The fuel cell system has an anode electrode to which an anode gas is supplied and a cathode electrode to which a cathode gas is supplied, and generates a fuel cell using the anode gas and the cathode gas, and supplies the anode gas to the anode electrode of the fuel cell. An anode gas supply system, a cathode gas supply system for supplying cathode gas to the cathode electrode of the fuel cell, and a controller for controlling the anode gas supply system and the cathode gas supply system.

  When the fuel cell performs a power generation operation, water accumulates inside the fuel cell, and flooding may occur. Flooding means that the flow path resistance is increased by narrowing the flow path formed inside the fuel cell with water. In this case, the power generation output of the fuel cell may be reduced. Flooding is likely to occur when the low power generation operation of the fuel cell is continued for a long time. The reason is that in low power generation operation, the flow rate per unit time of the anode gas supplied to the fuel cell is small, so the driving force to bring water existing inside the fuel cell to the outside of the fuel cell is small. is there.

  Patent Document 1 discloses a fuel cell system that suppresses flooding. According to this system, when the low output power generation operation is continuously operated for a long time, and the continuous execution time of the low output power generation operation passes the first time, the second time shorter than the first time, A utilization rate lowering step for reducing the anode gas utilization rate is performed while maintaining the power generation output of the fuel cell constant. In the utilization rate reduction process, the flow rate per unit time of the anode gas supplied to the fuel cell increases, so the flow rate of the anode gas is high, the water inside the fuel cell is taken out of the fuel cell, and flooding is suppressed. It is done.

  When the system shown in Patent Document 1 is applied to a fuel cell system of a type equipped with a reformer, the following problems may occur. That is, the flow rate per unit time of the anode gas supplied to the fuel cell increases in order to perform the utilization rate lowering process for reducing the anode gas utilization rate while maintaining the power generation output of the fuel cell constant, and as a result The concentration of the unreacted active material (hydrogen) contained in the anode off gas discharged from the battery increases. In this case, the anode off-gas is often returned to the combustion section of the reformer and recombusted, so that combustion in the combustion section becomes intense, and the temperature of the combustion section and thus the reforming section becomes excessively high. Precise control may be difficult.

JP 2006-24478 A

  The present invention has been made in view of the above-described circumstances. In the flooding suppression power generation process, power generation operation is performed while suppressing a decrease in the anode gas utilization rate of the fuel cell, and unreacted contained in the anode off-gas discharged from the fuel cell. A fuel cell system that is advantageous for suppressing flooding even when low-power generation operation in which the concentration of the active material (for example, hydrogen) increases and flooding is likely to occur is continued for a long time. It is an issue to provide.

  A fuel cell system according to the present invention includes a fuel cell having an anode electrode supplied with anode gas and a cathode electrode supplied with cathode gas, and an anode gas supply system for supplying anode gas to the anode electrode of the fuel cell. A cathode gas supply system for supplying a cathode gas to the cathode electrode of the fuel cell, and a control unit for controlling the anode gas supply system and the cathode gas supply system. When the low output continuous execution time of the low output power generation operation that is likely to cause flooding exceeds the first predetermined time t1 or more, the power generation is performed so as to suppress the decrease in the anode gas utilization rate in the fuel cell with respect to the low output power generation operation. The first control is executed to execute the flooding suppression power generation process for suppressing flooding for a second predetermined time t2 (t2 <t1) while driving. Cormorant.

  In the low power generation operation of the fuel cell, since the flow rate of the gas flowing through the gas flow path of the fuel cell is slow, the generated water tends not to be discharged by the gas, and the frequency of occurrence of flooding increases. The flooding suppression power generation process can be performed, for example, by making the flow velocity flowing through the gas flow path of the fuel cell faster than the low-power power generation operation. In this case, the generated water is easily taken out of the fuel cell by the reaction gas, and flooding of the fuel cell is suppressed.

  The flooding suppression power generation process can be performed by raising the temperature inside the fuel cell while generating power. In this case, since the liquid-phase water inside the fuel cell is easily vaporized, flooding can be suppressed. Further, the flooding process can be performed by reducing the humidity of at least one of the anode gas and the cathode gas supplied to the fuel cell.

  As described above, when the low output continuous execution time of the low output power generation operation in which flooding is likely to occur exceeds the first predetermined time t1, the frequency of occurrence of flooding in the fuel cell increases. Therefore, before the flooding actually occurs, or even if the flooding occurs, the control unit performs the flooding suppression power generation process for the second predetermined time t2 regardless of the magnitude of the power load request. (T2 <t1) The first control to be executed is performed. As a result, flooding of the fuel cell is suppressed, and a decrease in generated power due to flooding is suppressed. Even if the flooding suppression power generation process is continued for a long time, it is preferable to perform the flooding suppression power generation process within a predetermined time if the residual amount of water in the fuel cell increases.

  According to the present invention, when the low output continuous execution time of the low output power generation operation in which flooding is likely to occur exceeds the first predetermined time t1, the control unit suppresses the decrease in the anode gas utilization rate in the fuel cell. During the power generation operation, the first control is executed to execute the flooding suppression power generation process for a second predetermined time t2 (t1> t2). For this reason, the water existing inside the fuel cell is taken out of the fuel cell. As a result, flooding is suppressed, and a decrease in generated power due to flooding is suppressed.

  According to the present invention, in the flooding-suppressing power generation process, the power generation operation is performed while suppressing a decrease in the anode gas utilization rate in the fuel cell. For this reason, it can suppress that the density | concentration of the unreacted active material (for example, hydrogen) contained in the anode off gas discharged from the anode electrode of a fuel cell increases. Therefore, when applied to a system equipped with a reformer, a large amount of unreacted active material (hydrogen) contained in the anode off-gas is supplied to the combustion section of the reformer in the flooding-suppressing power generation process. And the controllability for controlling the temperature of the combustion section is ensured. Furthermore, when applied to a system of a type equipped with a storage unit for storing fuel gas (also referred to as anode gas) without being equipped with a reformer, unreacted activity contained in the anode off-gas in the flooding suppression power generation process. A large amount of a substance (for example, hydrogen) is suppressed from being supplied to the anode electrode of the fuel cell, and controllability for controlling the power generation output of the fuel cell is ensured.

It is a figure which shows the concept of a system typically. It is a piping diagram showing typically the structure of a heat exchange passage. It is a block diagram which shows a control part. It is a flowchart which the control part which concerns on other embodiment performs. It is a figure which concerns on another embodiment and shows the connection relation of a stack and commercial power.

  According to the present invention, the power generation operation of the fuel cell is roughly divided into a low output power generation operation and a high output power generation operation that operates at a higher output than the low output power generation operation. The high output power generation operation is roughly divided into a first high output power generation operation and a second high output power generation operation. The flooding suppression power generation process can be a first high-power power generation operation and / or a second high-power power generation operation.

  According to one aspect of the present invention, when the rated power output is, for example, 1000 W, the low power generation operation can be set to the lowest power generation output to 400 W or less, the first high output power generation operation exceeds 400 W to 800 W or less, and the second high output power generation. The operation is exemplified to be over 800 W to rated power output. In other words, if the rated power generation output is 100%, the low power generation operation can be set to the lowest power generation output to 40% or less, the first high output power generation operation exceeds 40% to 80% or less, and the second high output power generation operation is 80%. Exceeding% to 100% is exemplified. Depending on the type of fuel cell, when the rated power output is 1000 W, the low power generation operation can be made to the lowest power generation output to 300 W or less, the first high power generation operation is over 300 W to 800 W or less, and the second high output power operation is 800 W. Exceeding to rated power output is exemplified. In other words, when the rated power generation output is 100%, the low power generation operation can be set to the lowest power generation output to 30% or less, the first high power generation operation is more than 30% to 80% or less, and the second high power generation operation is 80%. Exceeding% to 100% is exemplified. Alternatively, assuming that the rated power output is 100%, the low power generation operation can be reduced to the lowest power generation output to 35% or less, the first high power generation operation is over 35% to 75% or less, and the second high output power operation is 75% Exceeding 100% is exemplified. Here, if the minimum power generation output is lower than this, the power generation operation of the fuel cell is not continued. The rated power output refers to the limit of use that guarantees continuous operation by the manufacturer under specified conditions, and is generally described in nameplates and catalogs.

  When the low output continuous execution time of the low output power generation operation in which flooding is likely to occur exceeds the first predetermined time t1, the control unit performs the high output power generation operation regardless of the power load demand by the user or the like. 2 It is preferable to execute the flooding suppression power generation process by executing a predetermined time t2 (t2 <t1). The flooding suppression power generation process is performed while suppressing a decrease in the anode gas utilization rate. Here, the anode gas utilization rate means the ratio (mol%) of the active material of the anode gas consumed as a power generation reaction among all the active materials contained in the anode gas supplied to the anode electrode of the fuel cell. . In the flooding-suppressing power generation process, the generated power of the fuel cell is increased as compared with the case of the low-power power generation operation regardless of the power load requirement. Therefore, in the flooding suppression power generation process, the flow rates of the anode gas and the cathode gas per unit time supplied to the fuel cell are increased as compared with the case of the low power generation operation. As a result, the flow velocity flowing through the gas flow path of the fuel cell is made faster than in the low-output power generation operation. As a result, the generated water is easily taken out of the fuel cell by the reaction gas, and the flooding of the fuel cell is suppressed. In this case, a decrease in the anode gas utilization rate is suppressed. In this case, there is a possibility that surplus generated power may be generated than the power consumed by the power load. In addition, it can set suitably in the range of t2 / t1 = 0.001-0.1, the range of 0.01-0.1, and the range of 0.02-0.1.

  According to one aspect of the present invention, an energy storage unit is provided that stores surplus generated power generated in the flooding suppression power generation process as thermal energy or electrical energy. In this case, surplus generated power can be generated by an electric heater to generate hot water directly or indirectly, and the hot water can be stored in a hot water storage tank. Moreover, it can be stored in a storage element such as a storage battery or a capacitor.

  The length of the first predetermined time t1 described above corresponds to the time when the generated power of the fuel cell is reduced due to flooding caused by the water generated inside the fuel cell by the low power generation operation. It is determined depending on the type and power generation conditions in the low power generation operation. The first predetermined time t1 is appropriately set to, for example, 1 hour or more, 3 hours or more, 5 hours or more, 8 hours or more, 10 hours or more, 20 hours or more, or the like.

  The length of the second predetermined time t2 (t2 <t1) during which the flooding-suppressing power generation process is executed is such that the liquid phase or vapor phase water present inside the fuel cell is converted into the fuel cell by the reaction gas in the high power generation operation. It is preferable to be determined by the type of fuel cell, power generation conditions, etc. so as to correspond to a time during which the generation of flooding can be suppressed. The second predetermined time t2 is shorter than the first predetermined time t1, and is set to, for example, 1 minute or more, 5 minutes or more, 10 minutes or more, 20 minutes or more. If the second predetermined time t2 is excessively long, there is a high possibility that surplus generated power will increase, and there is a high possibility that the generated water will further increase. Therefore, the upper limit value of the second predetermined time t2 can be 10 minutes, 15 minutes, 20 minutes, and 30 minutes.

  According to one aspect of the present invention, the high output power generation operation is executed for the third predetermined time t3 (t1> t3) or more before the continuous execution time of the low output power generation operation passes the end of the first predetermined time t1. Thereafter, when returning to the low output power generation operation, the control unit may correct the first predetermined time t1 and the second predetermined time t2 based on the execution time ta (t1> ta ≧ t3) of the high output power generation operation. preferable. Before the end of the first predetermined time t1, the high output power generation operation may be executed for a third predetermined time t3 (t1> t3) or longer. In this case, if the high output power generation operation is not excessively long, water generated inside the fuel cell by the low output power generation operation is discharged out of the fuel cell by the high output power generation operation, and flooding is less likely to occur. . For this reason, it is preferable that the control unit corrects the first predetermined time t1 and / or the second predetermined time t2 based on the execution time ta (t1> ta ≧ t3) of the high-output power generation operation.

  For example, when the execution time ta of the high-output power generation operation becomes long, water generated inside the fuel cell is taken out of the fuel cell by the high-output power generation operation, and flooding is less likely to occur. In consideration of this, the control unit corrects the first predetermined time t1 that is currently measured to be extended and the end of the first predetermined time t1 to be delayed before the end of the first predetermined time t1 has elapsed. It is preferable. Further, the control unit can correct the second predetermined time t2 during which the next flooding suppression power generation process is executed to be shortened.

  According to one aspect of the present invention, the high output power generation operation is executed for the third predetermined time t3 or more (t1> t3) before the low output continuous execution time of the low output power generation operation passes the end of the first predetermined time t1. After that, when returning to the low output power generation operation, the control unit resets the measurement of the first predetermined time t1 based on the execution time ta (t1> ta ≧ t3) of the high output power generation operation, Remeasurement of the predetermined time t1 can be started. Here, as described above, before the end of the first predetermined time t1, the high power generation operation may be executed for the third predetermined time t3 (t1> t3) or longer. In this case, water generated inside the fuel cell by the low output power generation operation is taken out of the fuel cell by the high output power generation operation, and flooding hardly occurs. For this reason, it is preferable that the control unit resets the measurement of the first predetermined time t1 and remeasures the first predetermined time t1 from the beginning before the end of the first predetermined time t1 has elapsed. For example, if the execution time ta of the high-output power generation operation becomes longer than the predetermined time, the amount of water generated inside the fuel cell is discharged outside the fuel cell by the high-power generation operation. Then, the control unit resets the measurement of the first predetermined time t1.

  According to one aspect of the present invention, the high output power generation operation is executed for the fourth predetermined time t4 or more (t1> t4) before the low output continuous execution time of the low output power generation operation passes the end of the first predetermined time t1. After that, when returning to the low power generation operation, the control unit starts the high output power generation operation from the execution time ta (t1> ta ≧ t4) of the high output power generation operation and the start time of the first predetermined time t1. It is preferable to correct the first predetermined time t1 and / or the second predetermined time t2 based on the elapsed time tx until the start. Here, when the high output power generation operation is executed for the fourth predetermined time t4 or more (t1> t4) before the end of the first predetermined time t1 has elapsed before the continuous execution time of the low output power generation operation has elapsed, the low output power generation operation is performed. As a result, the generated water generated inside the fuel cell is taken out of the fuel cell by the high-output power generation operation, and flooding is less likely to occur. For this reason, the control unit can correct the first predetermined time t1 and / or the second predetermined time t2 based on the execution time ta (t1> ta ≧ t4) of the high-output power generation operation and the elapsed time tx. preferable. For example, if the execution time ta related to the high-output power generation operation is long, if it is within a predetermined time, there is a high possibility that the generated water inside the fuel cell is taken out, so that it is difficult for flooding to occur, and the first predetermined time It is preferable that correction is made so that t1 is extended or correction is made so that the second predetermined time t2 is shortened. As the elapsed time tx is longer, it is estimated that the inside of the fuel cell is not excessively wet at the present time and is moderately wet. Therefore, the first predetermined time t1 is corrected to be extended, or the second predetermined time is set. It is preferable to correct so as to shorten the time t2. Each correction described above can take into account the magnitude of the power generation output in addition to time.

  According to one aspect of the present invention, when the stack is cooled with the stack cooling water, when the flooding suppressing power generation process is executed, the flow rate (liter / second) of the stack cooling water is increased as compared to the low power generation operation, Eventually, heat may be stored in the hot water tank.

  According to one aspect of the present invention, the anode gas supply system includes a reforming unit that generates anode gas to be supplied to the fuel cell by reforming the raw material, and the reforming unit is heated to a temperature range suitable for the reforming reaction. It is preferable to include a combustion section that performs this operation, and an anode offgas passage that supplies the anode offgas discharged from the anode electrode of the fuel cell to the combustion section and burns it in the combustion section. However, it is not limited to this structure.

(Embodiment 1)
FIG. 1 shows a first embodiment. A fuel cell system (hereinafter also referred to as a system) includes a stack 1 formed of a fuel cell, an anode gas supply system 2 that supplies anode gas to the anode electrode 10 of the stack 1, and a cathode gas to the cathode electrode 11 of the stack 1. A cathode gas supply system 5 to be supplied, a cooling system 6 for cooling the stack 1, and a control unit 700 are provided. The anode gas supply system 2 includes an anode gas supply passage 20 that connects the raw material source 21 and the anode 10 of the stack 1, a raw material valve 22 and a raw material pump 23 (raw material conveyance source) provided in the anode gas supply passage 20, A reformer 24 provided in the anode gas supply passage 20 to reform a raw material with water vapor to form a gaseous anode gas (hydrogen-containing gas, anode gas); a valve 25v on the outlet side of the reformer 24; A condenser 27 provided in the anode gas supply passage 20 for reducing the moisture of the gaseous anode gas, an inlet valve 28 for opening and closing the anode gas supply passage 20, and an off-gas of the anode gas discharged from the anode electrode 10 of the stack 1 Off gas passage 29 for supplying gas to combustion section 26, outlet valve 30 provided in anode off gas passage 29, and off And a condenser 29h to reduce the scan moisture. The anode gas supply passage 20 is provided with a desulfurizer 97 (a harmful component reducer). The desulfurization material 97 a (hazardous component reducing material) of the desulfurizer 97 has a function of reducing sulfur components as harmful components contained in the raw material before being supplied to the reforming unit 25. The anode gas supply passage 20 is provided with a bypass passage 46 having a bypass valve 45.

  The stack 1 has a large number of membrane electrode assemblies (MEAs). The MEA has a solid polymer type ion conductive membrane 12 (for example, fluorine-based, hydrocarbon-based, or glass-based) sandwiched between an anode 10 and a cathode 11. Therefore, the fuel cell used in Embodiment 1 is a polymer electrolyte fuel cell. A fuel cell generates electric energy by an oxidation-reduction reaction. The MEA may be a sheet type or a tube type. A sensor 10s for detecting the pressure in the anode 10 and a sensor 11s for detecting the pressure in the cathode 11 are provided. The stack 1 is connected to a commercial power source 49 through a breaker 47 and an inverter 48 having a cutoff function and a connection function, and is connected to the grid. The inverter 48 has an inverter controller 7. When the power of the stack 1 is insufficient, the power load 49x (for example, an internal load provided inside the system or an external load provided outside the system) is operated by the power of the commercial power supply 49.

  As shown in FIG. 1, a reformer 24 includes a reforming unit 25 that reforms a raw material with gas-phase or liquid-phase water, and a combustion unit that heats the reforming unit 25 to be suitable for the reforming reaction. 26 (heating unit). A sensor 25s for detecting the pressure in the reforming unit 25 is provided. As shown in FIG. 1, a reforming water system 34 for supplying reforming gas-phase or liquid-phase water to the reforming unit 25 is provided.

  The reforming water system 34 includes a tank 35 that stores the condensed water of the system as reforming water, a reforming water passage 36 that connects the tank 35 and the reforming unit 25, and water provided in the reforming water passage 36. It has a pump 37 (water conveyance source) and a water valve 38, and an evaporation section 39 that converts liquid phase water into a vapor phase to produce water vapor. Sensors 93 and 94 for detecting the amount of water in the tank 35 are provided. The evaporator 39 may be a separate body from the reformer 24 or may be integrally mounted on the reformer 24.

  A water purification system 9 is connected to the reforming water system 34. The water purification system 9 purifies the raw water supplied to the tank 35, and includes a valve 90 for supplying raw water and a first water having a first water purification material 91a having a water purification action such as an ion exchange resin. It has the refinement | purification part 91 and the 2nd water purification part 92 which has the 2nd water purification material 92a which has water purification effects, such as an ion exchange resin. Condensed water generated in each condenser of the system is supplied to the water purification units 91 and 92 by gravity or the like.

  Further, as shown in FIG. 1, the anode gas supply system 2 includes a branch passage 40 having a valve 40 a for communicating the anode gas supply passage 20 and the combustion unit 26, an air passage 41, and a pump provided in the air passage 41. 42 (combustion air conveyance source). The air passage 41 may communicate with the cathode gas supply passage 52. The raw material of the raw material source 21 is supplied from the branch path 40 to the combustion unit 26 as combustion gas. When the pump 42 is operated, combustion air is supplied to the combustion unit 26. As a result, combustion gas is combusted in the combustion part 26, and the reforming part 25 is heated. In addition, although the raw material reformed in the reforming unit 25 may be gaseous or liquid, a gaseous state such as city gas is preferable. In some cases, examples of the raw material include LPG, kerosene, methanol, dimethyl ether, gasoline, and biogas instead of city gas. The exhaust gas combusted in the combustion unit 26 is discharged to the exhaust passage 43 and is discharged to the outside after the moisture is reduced by the condenser 43h.

  As shown in FIG. 1, the cathode gas supply system 5 purifies the humidifier 50 having a moisture retaining member 50c that partitions the humidification path 50a and the moisture absorption path 50b, and the cathode gas (air) with a filter 51 (purifying material). After that, the cathode gas supply passage 52 that supplies the cathode electrode 11 of the stack 1 via the humidification passage 50a of the humidifier 50, the cathode gas pump 53 (cathode gas conveyance source) provided in the cathode gas supply passage 52, and the cathode gas The inlet valve 54 for opening and closing the supply passage 52 and the wet cathode off-gas discharged from the cathode electrode 11 of the stack 1 are discharged to the outside after the moisture is reduced through the moisture absorption path 50b and the condenser 55h of the humidifier 50. Cathode gas discharge passage 55 and a return path that bypasses the moisture absorption passage 50b of the humidifier 50 in communication with the cathode gas discharge passage 55 With a bypass 56 and a bypass valve 57 for return flow of the cathode off-gas discharged from the cathode 11 of the stack 1 to the bypass passage 56. The cathode gas supply passage 52 is provided with a sensor 52s that detects the flow rate per unit time of the cathode gas (air) flowing therethrough.

  The moisture retention member 50c has moisture retention and gas barrier properties, and is formed of, for example, an ion exchange membrane. As can be understood from FIG. 1, the bypass valve 57 can change the ratio of the flow rate flowing in the moisture absorption path 50 b of the humidifier 50 and the flow rate flowing in the bypass path 56. Further, the detour 58 for the forward path that communicates with the cathode gas supply passage 52 and bypasses the humidification path 50 a of the humidifier 50, and the forward path for flowing the cathode gas just before being supplied to the cathode electrode 11 of the stack 1 to the detour 58. And a bypass valve 59. The bypass valve 59 can change the ratio of the flow rate flowing through the humidification path 50 a of the humidifier 50 and the flow rate flowing through the bypass circuit 58. In some cases, the detour 58 for the forward path and the detour valve 59 for the forward path can be eliminated.

  The cooling system 6 includes a circulation passage 60 that communicates with the refrigerant passage 13 formed inside the stack 1, a refrigerant pump 61 (refrigerant conveyance source) that circulates refrigerant (cooling liquid such as cooling water) in the circulation passage 60, and the like. And a temperature sensor 62 that is provided in the circulation passage 60 and detects the temperature of the refrigerant in the circulation passage 60, and a heater 63 (power consumption element) that heats the refrigerant in the circulation passage 60. When the stack 1 is activated, the control unit 700 can preheat the stack 1 by causing the heater 63 to generate heat by using the power from the commercial power supply 49 or the power storage element 79 to preheat the refrigerant in the circulation passage 60. The temperature of the refrigerant in the circulation passage 60 substantially corresponds to the operating temperature of the stack 1. Further, the cooling system 6 includes a branching path 65 branched from the circulation passage 60, a refrigerant processing unit 66, a flow rate sensor for detecting a flow rate flowing through the refrigerant processing unit 66, or a liquid level sensor for detecting a liquid level in the refrigerant processing unit 66. And a sensor 67 formed by The refrigerant treatment material 66a of the refrigerant treatment unit 66 is formed of an ion exchange resin or the like so as to reduce impurities contained in the refrigerant (for example, a cooling liquid such as cooling water) and improve the electric insulation of the refrigerant. . When the refrigerant pump 61 is activated, the refrigerant circulates in the circulation passage 60 and the refrigerant passage 13 of the stack 1, and heat of the stack 1 can be taken away. At this time, the electrical insulation of the refrigerant is enhanced by the refrigerant treatment material 66a.

  A hot water storage system 8 is provided. The hot water storage system 8 includes a hot water storage passage 80, a heat exchanger 81 that exchanges heat between the circulation passage 60 and the hot water storage passage 80, a pump 82 (a hot water supply source) that transfers water in the hot water storage passage 80, and the hot water storage passage 80. It has a hot water storage tank 85 connected, a replenishment passage 84 for replenishing replenishment water (for example, tap water) when water in the hot water storage tank 85 is insufficient, and a hot water consumption passage 85x for consuming hot water in the hot water storage tank 85. When the pump 82 operates, the water in the hot water storage passage 80 is conveyed, the thermal energy of the circulation passage 60 is transmitted to the hot water storage passage 80, the water temperature of the hot water storage passage 80 rises, and the thermal energy of the hot water storage tank 85 rises. A radiator device 89 provided between the heat exchanger 81 and the hot water tank 85 is provided. The radiator device 89 has a radiator fan 89a. When the hot water in the hot water storage tank 85 is full, the radiator fan 89a is rotationally driven to blow air, thereby promoting the heat radiation of the radiator device 89 and lowering the water temperature of the hot water storage passage 80.

  During the power generation operation of the stack 1, the control unit 700 operates the pump 23 with the anode gas valve 22 opened while the stack 1 and the power load 49x are electrically connected, so that the gaseous raw material of the raw material source 21 is supplied. The water is supplied to the reforming unit 25 of the reformer 24, and the water pump 37 is further operated, and the reforming water in the tank 35 is vaporized by the evaporation unit 39 and then supplied to the reforming unit 25. As a result, the raw material is steam reformed in the reforming unit 25 to become an anode gas (hydrogen-containing gas). The anode gas is supplied to the anode electrode 10 of the stack 1 through an open inlet valve 28 after excess moisture is removed by the condenser 27. Further, the control unit 700 operates the cathode gas pump 53 with the valves 54, 57, 59 opened, passes the cathode gas (air) through the filter 51, and humidifies the humidification path 50 a of the humidifier 50. , And supplied to the inlet of the cathode electrode 11 of the stack 1. As a result, the stack 1 performs a power generation operation.

  However, since the composition of the anode gas reformed by the reformer 24 may not be sufficiently stable at the beginning of startup, the control unit 700 closes the inlet valve 28 and the outlet valve 30 with the bypass valve. 45 is opened, and the anode gas is caused to flow through the bypass passage 46 to the combustion unit 26 and burn in the combustion unit 26, and does not flow to the anode 10 of the stack 1. When the composition of the reformed anode gas is stabilized, the control unit 700 opens the inlet valve 28 and the outlet valve 30, closes the pass valve 45, and supplies the anode gas to the anode electrode 10 of the stack 1 instead of the bypass passage 45. To do.

  In the power generation operation, the anode gas off-gas discharged from the outlet of the anode electrode 10 of the stack 1 has a combustible component (unreacted hydrogen), and therefore flows through the anode off-gas passage 29 and the moisture is reduced by the condenser 29h. Then, it is discharged to the combustion section 26 and burned. The combustion exhaust gas is discharged outward from the exhaust passage 43. On the other hand, the cathode off gas discharged from the outlet of the cathode electrode 11 of the stack 1 flows from the cathode gas discharge passage 55 to the moisture absorption passage 50 b of the humidifier 50. By controlling the bypass valve 57, it is possible to variably control the ratio between the flow rate of the cathode off gas flowing through the moisture absorption path 50b of the humidifier 50 and the flow rate of the cathode off gas flowing through the bypass circuit 56. Each device and each element of the system described above are accommodated in the accommodation chamber 501 of the housing 500.

  As shown in FIG. 2, the condensers 27, 43h, 29h, and 55h are a kind of heat exchanger, and cool water vapor contained in the gas that passes through these condensers 27, 43h, 29h, and 55h. To condense. A heat exchange passage 520 through which a heat exchange medium (cooling water) for cooling the condensers 27, 43h, 29h, and 55h flows is provided together with a pump 521 (heat exchange medium conveyance source). As a result, the heat exchange medium flowing through the heat exchange passage 520 collects exhaust heat generated in the system, and transmits the exhaust heat to the water in the hot water storage passage 80 via the heat exchanger 87. Thereby, the thermal energy accumulated as hot water in the hot water tank 85 is increased.

  As shown in FIG. 3, the control unit 700 includes an input processing circuit 70, a CPU 71 having a timer function, memories 72 and 73 as memories, and an output processing circuit 74. The control unit 700 includes auxiliary devices such as valves 22, 25v, 28, 30, 40a, 90, 54, 57, 59, pumps 23, 37, 42, 61, 53, 82, 521, heater 63, and radiator fan 89a. Control. The power for driving each of these auxiliary machines is basically covered by the power generated by the stack 1, and when the power is insufficient, the power of the commercial power supply 49 is consumed.

  By the way, according to the present embodiment, the power generation operation of the stack 1 is roughly divided into the low power generation operation, the first high power power generation operation, and the second high power power generation operation from the low output side. When the rated power output is 1000 W, the low power generation operation can be set to the lowest power generation output to 400 W or less, the first high power generation operation is over 400 W to 800 W or less, and the second high power generation operation is over 800 W to the rated power output. The In other words, if the rated power generation output is 100%, the low power generation operation can be set to the lowest power generation output to 40% or less, the first high output power generation operation exceeds 40% to 80% or less, and the second high output power generation operation is 80%. % To 100%.

  According to the present embodiment, the low power generation operation tends to easily generate flooding. This is because the flow rate of the anode gas and cathode gas is slow, and it is not easy to take out the water inside the stack 1 to the outside of the stack 1. There are times when the low output continuous operation time of the low output power generation operation is long, that is, the first predetermined time t1 (or more) elapses. For example, continuous power generation operation at night. In addition, only a part of the power load 49x driven by the generated power of the system is used. Thus, when low power generation operation continues for a long time, it is estimated that the probability that flooding will occur is high. Therefore, when the low output power generation operation continues for the first predetermined time t1, the control unit 700 performs the high output power generation operation for the second predetermined time t2 regardless of whether or not the power load 49x is requested by the user or the like. (T1> t2) By executing, the flooding suppression power generation process is executed. In high-output power generation operation, it is preferable to keep the power generation output as constant as possible. In the high-output power generation operation constituting the flooding suppression power generation process, the reaction gas supplied to the inside of the stack 1 (the anode gas supplied to the anode electrode 10 and the cathode gas supplied to the cathode electrode 11) per unit time. The flow rate is large and the gas flow rate is fast, so that water existing in the gas flow path inside the stack 1 can be easily taken out of the stack 1. For this reason, if a high output power generation operation is executed, the excessively wet state inside the stack 1 can be shifted in the drying direction. However, if the high-output power generation operation is continuously operated for an excessively long time, excessive heat or excessive power may be generated. Therefore, it is preferable to define an upper limit of the flooding suppression power generation processing time.

  The above-described flooding suppression power generation process is performed while suppressing a decrease in the anode gas utilization rate in the stack 1, that is, while suppressing a decrease in the anode gas utilization rate with respect to the low power generation operation. As described above, in the flooding suppression power generation process, the control unit 700 suppresses a decrease in the anode gas utilization rate with respect to the low output power generation operation. The generated power of the stack 1 is increased as compared with the above case. Therefore, in the flooding suppression power generation process according to the present embodiment, the unit time of the anode gas (fuel gas) and the cathode gas (oxidant gas) per unit time supplied to the stack 1 than in the case of the low power generation operation. The flow rate per hit increases. Therefore, there is a possibility that surplus generated power may be generated than the power consumed by the power load 49x.

  Therefore, according to the present embodiment, an energy storage unit that stores surplus generated power generated in the flooding suppression power generation process as thermal energy or electrical energy is provided. In this case, surplus generated power is generated by the electric heater 63 to generate hot water directly or indirectly, and the hot water is stored in the hot water storage tank 85 as an energy storage unit via the heat exchanger 81 and the hot water storage passage 80. Heat storage operation can be performed. Further, the storage element 79a can be turned on, and a storage operation for storing electrical energy in the storage element 79 including a storage battery and / or a capacitor that functions as an energy storage unit can be executed. In this case, in winter or cold districts, in order to use surplus generated power, the heater 63 is turned on to generate hot water, and the heat storage operation for storing the hot water in the hot water storage tank 85 as an energy storage unit is given priority. When the hot water in the hot water tank 85 is full, it is possible to carry out a power storage operation that causes the power storage element 79 to store electricity. Alternatively, in summer and in extremely hot regions, priority is given to a power storage operation for storing surplus generated power in the power storage element 79, and when the power storage element 79 is fully charged, the surplus generated power is secondarily generated by the heater 63. It is also possible to execute a heat storage operation for storing the heat energy of the hot water as hot water in the hot water storage tank 85 as an energy storage unit. When the power storage element 79 is fully charged and the hot water in the hot water tank 85 is full, the radiator fan 89a of the radiator device 89 provided between the heat exchanger 81 and the hot water tank 85 is rotated. It may be driven to promote the heat radiation of the radiator device 89, and the water temperature upstream of the heat exchanger 81 in the hot water storage passage 80 may be lowered.

  According to the present embodiment, the first predetermined time t1 described above corresponds to a time during which flooding occurs due to water generated inside the stack 1 due to low power generation operation and the generated power of the stack 1 decreases. It is preferable to be determined by the type of the stack 1, the power generation conditions in the low-power power generation operation, and the like. The first predetermined time t1 is basically set in advance as, for example, 3 hours, 5 hours, 8 hours, 10 hours, or the like.

  In addition, the second predetermined time t2 (t2 <t1), which is the time during which the flooding suppression power generation process is executed, is performed by stacking the liquid phase or vapor phase water present in the stack 1 with the reactive gas by the high output power generation operation. 1 is preferably determined according to the type of stack 1, power generation conditions, and the like so as to correspond to a time during which discharge can be performed from 1 and the occurrence of flooding can be suppressed. The second predetermined time t2 is set in advance as, for example, 1 minute, 5 minutes, 10 minutes, 20 minutes, or the like according to the type of the stack 1 or the like. If the second predetermined time t2 is excessively long, there is a high possibility that surplus generated power will increase.

  Now, further description will be made on the main part of the present embodiment. When the low output power generation operation in which flooding is likely to occur is continuously performed, when the low output continuous execution time of the low output power generation operation has passed the first predetermined time t1, the control unit 700 causes flooding as it is. The flooding suppression power generation process is executed by executing the high-output power generation operation for the second predetermined time t2 (t1> t2) regardless of the magnitude of the request of the power load 49x by the user or the like. In the flooding-suppressing power generation process, the decrease in the anode gas utilization rate is suppressed, that is, the anode gas utilization rate per unit time supplied to the anode electrode 10 of the stack 1 is maintained while maintaining the anode gas utilization rate for the low power generation operation. The flow rate per unit time of the cathode gas (air) supplied to the cathode electrode of the stack 1 is increased. In this case, the flow rate per unit time of the reforming water supplied to the reforming unit 25 is increased.

  As a result, in the flooding suppression power generation process, the flow rates of the anode gas and the cathode gas per unit time supplied to the stack 1 are increased as compared with the case of the low output power generation operation. Therefore, there is a possibility that surplus generated power may be generated than the power consumed by the power load 49x. Therefore, a hot water storage tank 85 and a power storage element 79 are provided as an energy storage unit for storing surplus generated power generated in the flooding suppression power generation process as heat energy or electric energy. In this case, surplus generated power can be generated by the electric heater 63 to heat the water in the circulation passage 60, and as a result, can be stored as hot water in the hot water tank 85 via the heat exchanger 81. Further, surplus generated power can be stored in the storage element 79 connected to the stack 1 as electric energy.

  The first predetermined time t1 and the second predetermined time t2 described above are stored in advance in the area of the memory 72 of the control unit 700 as a map. Here, the second predetermined time t2 corresponds to a time during which liquid-phase water existing in the stack 1 is discharged from the stack 1 by the reactive gas by high-power power generation operation, and generation of flooding can be suppressed. It is determined by the type of stack 1, power generation conditions, and the like. The second predetermined time t2 is set as, for example, 1 minute, 5 minutes, 10 minutes, 20 minutes, or the like. Here, when the second predetermined time t2 is excessively long, there is a high possibility that surplus generated power will increase, and flooding may occur. For this reason, the upper limit value of the second predetermined time t2 can be set to, for example, 30 minutes.

  When the low output continuous execution time of the low output power generation operation passes the first predetermined time t1, the control unit 700 executes the flooding suppression power generation process for the second predetermined time t2. In this case, the flow rate (L / sec) of the anode gas supplied to the anode electrode 10 can be increased, and the flow rate (L / sec) of the cathode gas supplied to the cathode electrode 11 can be increased. As a result, the gas flow rate of the anode 10 and the gas flow rate of the cathode 11 are increased, so that water existing in the stack 1 is easily moved. As a result, the reactive gas in the flooding suppression power generation process is discharged to the outside of the stack 1, and flooding is prevented in advance. Even in the initial stage of flooding, the reactive gas in the flooding suppression power generation process is discharged outside the stack 1 to prevent flooding. In addition, if 2nd predetermined time t2 passes, the control part 700 will be able to perform a low output electric power generation operation again according to a user's request | requirement.

  In order to suppress flooding, it is also conceivable to perform flooding-suppressing power generation processing by high-power power generation operation while actively reducing the anode gas utilization rate with respect to low-power power generation operation as in Patent Document 1. In this case, in order to increase the flow rate of the anode gas supplied to the anode electrode 10 of the stack 1 and reduce the utilization rate of the anode gas, the unreacted active material contained in the anode off-gas discharged from the anode electrode 10 of the stack 1 The concentration of (hydrogen) increases excessively. That is, the concentration of unreacted hydrogen contained in the anode off gas supplied from the anode 10 to the combustion unit 26 of the reformer 24 through the anode off gas passage 29 increases. For this reason, the combustion of the combustion part 26 of the reformer 24 becomes excessive, and the temperature of the reforming part 25 may become excessively high unless the combustion of the combustion part 26 is strictly controlled.

  In this regard, according to the present embodiment, the flooding suppression power generation process is performed while suppressing a decrease in the anode gas utilization rate with respect to the low output power generation operation. Therefore, although the flow rate per unit time of the anode gas supplied to the anode electrode 10 of the stack 1 increases, the anode gas active material (hydrogen) is favorably consumed as a power generation reaction in the stack 1. Therefore, when the flooding suppression power generation process is being performed, it is possible to suppress an excessive increase in the concentration of unreacted hydrogen contained in the anode off-gas discharged from the anode electrode 10 of the stack 1. That is, an excessive increase in the concentration of unreacted hydrogen contained in the anode off gas supplied from the anode off gas passage 29 to the combustion unit 26 of the reformer 24 can be suppressed. For this reason, it is suppressed that the combustion of the combustion part 26 of the reformer 24 becomes excessive, and the temperature of the reforming part 25 is suppressed from becoming excessively high. Therefore, the reforming reaction in the reforming unit 25 is maintained well.

  Furthermore, even when applied to a system without a reformer, a large amount of unreacted active material (hydrogen) contained in the anode off-gas is suppressed from being supplied to the anode electrode 10 of the stack 1, Good controllability of the power generation output of the stack 1 is ensured.

  As described above, in the flooding suppression power generation process, the flow rate per unit time of the anode gas supplied to the anode electrode 10 and the flow rate per unit time of the cathode gas supplied to the cathode electrode 11 are increased. In this case, since the drive amount (rotation speed) of the pumps 23, 42, 53, and 37 is increased as compared with the low-output power generation operation, the power consumption increases. However, according to the present embodiment, the flooding suppression power generation process can easily generate surplus generated power, and the surplus power can be used to increase the drive amount of the pumps 23, 42, 53, 37. Effective use can be achieved. Moreover, since the flooding suppression power generation process is a high power generation, the stack 1 may be heated. In this case, when the flooding suppression power generation process is executed, the rotational speed (driving amount) of the pump 61 per unit time is increased as compared with the low-power power generation operation, and the flow rate (liter / second) of the stack cooling water flowing through the circulation passage 60 is increased. The hot water in the hot water storage passage 80 may be heated through the heat exchanger 91 and stored in the hot water storage tank 85.

(Embodiment 2)
Since this embodiment has basically the same configuration as that of the first embodiment and has the same function and effect, FIGS. 1 to 3 are applied mutatis mutandis. Hereinafter, the description will focus on the different parts. When the low output power generation operation is being performed, the power generation history information regarding the low output power generation operation is continuously stored in the area of the memory 72 of the control unit 700. Then, it is determined whether or not the first predetermined time t1 has elapsed during the continuous execution time of the operation while maintaining the low output power generation operation. When the continuous execution time of the low output power generation operation exceeds the first predetermined time t1, the control unit 700 sets the residual moisture estimated value α related to the generated power of the low output power generation operation at the first predetermined time t1 in the low output power generation operation. Obtained based on power generation history information. The moisture residual estimated value α predicts the amount of moisture at the current time point present in the stack 1, and basically has a form obtained based on a value obtained by time-integrating the generated power in the low-output power generation operation. Illustrated. In addition, the moisture residual estimated value α is basically a value obtained by integrating the generated power in the low output power generation operation over time, and a correction coefficient α1 regarding the total flow rate of the anode gas supplied to the anode electrode 10 in the low output power generation operation. In the low power generation operation, the form obtained based on the correction coefficient α2 related to the total flow rate of the anode gas supplied to the cathode electrode 11 is exemplified.

  Further, the second predetermined time t2 during which the flooding suppression power generation process is executed is obtained based on the map or arithmetic expression based on the moisture residual estimated value α. The map or the calculation formula defines the relationship between the moisture residual estimated value α and the second predetermined time t2, and is set to increase the second predetermined time t2 within the predetermined time when the estimated value increases. . When the first predetermined time t1 elapses, the control unit 700 starts the flooding suppression power generation process and executes the second predetermined time t2. When the second predetermined time t2 has elapsed, the control unit 700 ends the flooding suppression power generation process. In this case, the low-output power generation operation can be executed again according to the user's request.

  By the way, when the low output power generation operation is being performed, the high output power generation operation is performed according to the demand of the power load before the continuous execution time of the low output power generation operation has passed the end of the first predetermined time t1 (for example, 3 hours). May be executed for the third predetermined time t3 or more (t1> t3, t3 = 10 minutes, for example). This is because in the present embodiment, the power generation output is basically controlled following the power load. In this case, it is presumed that the water generated inside the stack 1 due to the low output power generation operation was taken out of the stack 1 due to the fast gas flow rate during the high output power generation operation. For this reason, before the end of the first predetermined time t1, the high-power generation operation is performed for the third predetermined time t3 or more (for example, 5 minutes, t1> t3). It is estimated that it does not occur, and the first predetermined time t1 is reset and returned to zero. In this case, if the low-output power generation operation is continued, the control unit 700 starts remeasurement of the first predetermined time t1.

(Embodiment 3)
Since this embodiment has basically the same configuration as that of the second embodiment and has the same function and effect, FIGS. 1 to 3 are applied mutatis mutandis. Hereinafter, the description will focus on the different parts. When the continuous execution time of the low output power generation operation has passed the end of the first predetermined time t1, the control unit 700 obtains the moisture residual estimated value α related to the generated power of the low output power generation operation at the first predetermined time t1. Further, the control unit 700 obtains a second predetermined time t2 during which the flooding suppression power generation process is executed from a map or an arithmetic expression based on the moisture residual estimation value α. The map or the arithmetic expression defines the relationship between the moisture residual estimated value α and the second predetermined time t2. Then, the control unit 700 executes the flooding suppression power generation process for the second predetermined time t2. If 2nd predetermined time t2 passes, the control part 700 will be able to perform a low output electric power generation operation again according to a user's request | requirement.

  By the way, when the low-output power generation operation is being executed, the power is continuously output in the latter period of the first predetermined time t1 before the low output continuous execution time of the low-output power generation operation has passed the first predetermined time t1 (for example, 3 hours). The high output power generation operation may be executed for a third predetermined time t3 or more (t1> t3, t3 = for example, 10 minutes) due to a load request. In this case, water generated inside the stack 1 due to the low output power generation operation is taken out of the stack 1 when the high output power generation operation is executed in the latter half of the period when the first predetermined time t1 is measured. It is estimated that the probability is high. Therefore, before the end of the first predetermined time t1 elapses during the low output continuous operation time of the low output power generation operation, the high output power generation operation is performed for the third predetermined time t3 or more (for example, 3 When the time, t1> t3) is being executed, the controller 700 estimates that the water in the stack 1 has been discharged out of the stack 1, and resets the first predetermined time t1 to zero. Then, the control unit 700 remeasures the first predetermined time t1 from 0. Here, the latter period of the first predetermined time t1 means, for example, the latter half of the time period from the start time to the end time of the first predetermined time t1. However, it is not limited to this. Depending on the case, the time zone may be divided into n to be the last period. When the high-output power generation operation is executed in the latter period of the first predetermined time t1, the water in the stack 1 is discharged to the outside of the stack 1, and it is estimated that the excessively wet state inside the stack 1 has been eliminated.

  Also in the present embodiment, as described above, the flooding suppression power generation process is performed so that the anode gas utilization rate does not decrease as much as possible with respect to the low power generation operation. Therefore, in the flooding suppression power generation process, the flow rate per unit time of the anode gas supplied to the anode electrode 10 of the stack 1 increases, and the increased anode gas is basically consumed as a power generation reaction in the stack 1. For this reason, in the flooding suppression power generation process, the concentration of unreacted hydrogen contained in the anode off-gas discharged from the anode 10 of the stack 1 to the combustion unit 26 of the reformer 24 via the anode off-gas passage 29 is excessive. The increase is suppressed. For this reason, in the flooding suppression power generation process, the combustion of the combustion unit 26 is suppressed from being excessive, and the temperature of the reforming unit 25 is suppressed from becoming excessively high. Therefore, the temperature in the reforming part 25 can be controlled well, and the advantage that the reforming reaction is maintained well can be obtained.

(Embodiment 4)
Since this embodiment has basically the same configuration as that of the first embodiment and has the same function and effect, FIGS. 1 to 3 are applied mutatis mutandis. Hereinafter, the description will focus on the different parts. When the first predetermined time t1 elapses during the low output power generation operation for the low output power generation operation, the control unit 700 obtains the moisture residual estimated value α related to the generated power of the low power generation operation at the first predetermined time t1, and performs flooding-suppressed power generation. A second predetermined time t2 during which the process is executed is obtained from a map or an arithmetic expression based on the moisture residual estimated value α. And the control part 700 performs the flooding suppression power generation process for 2nd predetermined time t2. If 2nd predetermined time t2 passes, the control part 700 will be able to perform a low output electric power generation operation again according to a user's request | requirement.

  By the way, when the low output power generation operation is being performed, the high output power generation operation is performed according to the demand of the power load before the first predetermined time t1 (for example, 5 hours) elapses. 4 There are times when it is executed for a predetermined time t4 (for example, 15 minutes, t1> t4) or more. In this case, it is estimated that a considerable portion of the water that was present inside the stack 1 due to the low-power generation operation is taken out of the stack 1 due to the high-power generation operation, and flooding is less likely to occur.

  For this reason, the control part 700 calculates | requires execution time ta (t1> ta> = t4) of the high output power generation operation performed before the end of the 1st predetermined time t1 passes. Before the end of the first predetermined time t1, the control unit 700 sets the first predetermined time t1 currently being measured and the second predetermined time t2 of the flooding suppression power generation process to be executed next time to the execution time ta ( Correction is made based on t1> ta ≧ t4). Specifically, when the execution time ta of the high-output power generation operation performed before the end of the first predetermined time t1 elapses, the control unit 700 maps or calculates the first predetermined time t1 currently measured. Is corrected based on the above, and corrected so as to delay the end of the first predetermined time t1 currently being measured. Alternatively, the second predetermined time t2 during which the flooding suppression power generation process is executed is corrected in a direction of shortening based on a map or an arithmetic expression. The reason is that a considerable amount of water inside the stack 1 is discharged to the outside of the stack 1 due to the execution time ta of the high-output power generation operation that is executed before the end of the first predetermined time t1 elapses. It is because it is estimated that it is a moderate wet state (dry taste). In the correction, it is preferable to consider the magnitude of the power generation output at the execution time ta. Specifically, for example, when the power generation output is large, the first predetermined time t1 is lengthened.

  In the above correction, it is preferable to consider the magnitude of the power generation output value of the high power power generation operation. In this case, if the power generation output value of the high power power generation operation is high, the water inside the stack 1 is more easily taken out to the outside. Therefore, in consideration of the accumulated value of the power generation output of the high output power generation operation at the execution time ta, the control unit 700, when the accumulated value is large, based on the map or the arithmetic expression, the first predetermined time t1 currently being measured. Correction can be made in the direction of delaying the end, or correction can be made in the direction of shortening the second predetermined time t2 during which the flooding suppression power generation process is executed.

  Here, in the high-output power generation operation, the flow rate of the anode gas supplied to the anode electrode 10 and the flow rate of the cathode gas supplied to the cathode electrode 11 are high. For this reason, if the execution time ta is long, it is presumed that the amount of water present inside the stack 1 is discharged outside the stack 1 and flooding hardly occurs. In this case, before the end of the first predetermined time t1 arrives, the extension of the first predetermined time t1 currently being measured is lengthened, and the end is corrected so as to be delayed by that amount. Or it correct | amends so that 2nd predetermined time t2 in which flooding suppression power generation processing is performed may be shortened.

  Further, when the execution time ta of the high-output power generation operation is excessively short, it is estimated that the amount of the water existing inside the stack 1 is discharged out of the stack 1 is small. In this case, the first predetermined time t1 and the second predetermined time t2 are not corrected. In the present embodiment as well, in the flooding suppression power generation process, the power generation operation is performed while suppressing a decrease in the anode gas utilization rate with respect to the low power generation operation.

(Embodiment 5)
Since this embodiment has basically the same configuration as that of the fourth embodiment and has the same function and effect, FIGS. 1 to 3 apply mutatis mutandis. Hereinafter, the description will focus on the different parts. When the low-output power generation operation is being executed, the high-output power generation operation is performed before the first predetermined time t1 (for example, 5 hours) elapses and in the latter period of the first predetermined time t1. May be executed for a fourth predetermined time t4 (for example, 15 minutes, t1> t4) or more. In this case, it is estimated that a considerable portion of the water that was present inside the fuel cell due to the low output power generation operation is taken out of the stack 1 by the high output power generation operation and flooding is unlikely to occur.

  For this reason, when the low output power generation operation is being performed, the control unit 700 is configured to execute the low output continuous operation time of the low output power generation operation before the first predetermined time t1 and the latter period of the first predetermined time t1. The execution time ta (t1> ta ≧ t4) of the high-output power generation operation performed in is obtained. Furthermore, the control unit 700 corrects the first predetermined time t1 currently measured and the second predetermined time t2 of the flooding suppression power generation process based on the execution time ta (within a predetermined time). Specifically, when the execution time ta of the high output power generation operation that is performed before the end of the first predetermined time t1 elapses is long, the water inside the stack 1 It is estimated that flooding is difficult to take out. Then, the control unit 700 corrects the first predetermined time t1 currently measured by extending the first predetermined time t1 currently measured based on a map or an arithmetic expression. Alternatively, the second predetermined time t2 when the flooding suppression power generation process is executed is corrected based on a map or an arithmetic expression.

  Specifically, if the execution time ta of the high-output power generation operation is long within the specified time, it is estimated that the water existing inside the stack 1 has been discharged out of the stack 1, and thus the first predetermined value currently being measured. The time t1 is extended for a long time, and the end of the first predetermined time t1 currently being measured is delayed accordingly. Alternatively, the second predetermined time t2 during which the flooding suppression power generation process is executed is shortened. Also in the present embodiment, the flooding suppression power generation process is performed while suppressing a decrease in the anode gas utilization rate with respect to the low power generation operation.

(Embodiment 6)
Since this embodiment has basically the same configuration as each of the above-described first embodiments and has the same function and effect, FIGS. 1 to 3 are applied mutatis mutandis. Hereinafter, the description will focus on the different parts. When the low output power generation operation is being executed and the low output continuous execution time of the low output power generation operation has passed the first predetermined time t1, the control unit 700 sets the second predetermined time t2 during which the flooding suppression power generation process is executed. Obtained by map or arithmetic expression. And the control part 700 performs the flooding suppression power generation process for 2nd predetermined time t2. If 2nd predetermined time t2 passes, the control part 700 will be able to perform a low output electric power generation operation again according to a user's request | requirement.

  By the way, there is a case where the high output power generation operation is executed for the fourth predetermined time t4 or more (t1> t4) before the low output continuous execution time of the low output power generation operation passes the end of the first predetermined time t1. In this case, before the end of the first predetermined time t1, the water generated inside the fuel cell by the low output power generation operation is estimated to be taken out of the stack 1 by the high output power generation operation. Therefore, when the high-output power generation operation is executed for the fourth predetermined time t4 or more (t1> t4) before the end of the first predetermined time t1, the control unit 700 executes the execution time ta of the high-output power generation operation. And an elapsed time tx from the start of the first predetermined time t1 to the start of the high-output power generation operation. Then, the control unit 700 corrects the lengths of the first predetermined time t1 and the second predetermined time t2 based on the execution time ta of the high-output power generation operation and the elapsed time tx, respectively.

  For example, as the execution time ta of the high-output power generation operation is longer or the elapsed time tx is longer, the water in the stack 1 is taken out and flooding is less likely to occur. For this reason, the control unit 700 corrects the first predetermined time t1 currently measured to be extended, or corrects the second predetermined time t2 to be shortened.

  That is, according to the present embodiment, the relationship among the execution time ta, the elapsed time tx, and the first predetermined time t1 of the high-output power generation operation is set as a map or an arithmetic expression. This map or arithmetic expression is stored in the area of the memory 72 of the control unit 700. Therefore, the control unit 700 obtains the first predetermined time t1 based on the execution time ta and the elapsed time tx of the high-output power generation operation.

  Furthermore, the relationship between the execution time ta, the elapsed time tx, and the second predetermined time t2 of the high-output power generation operation is set as a map or an arithmetic expression. This map or arithmetic expression is stored in the area of the memory 72 of the control unit 700. Therefore, the control unit 700 obtains the second predetermined time t2 based on the execution time ta and the elapsed time tx. In this embodiment as well, the flooding suppression power generation process is performed while suppressing a decrease in the anode gas utilization rate with respect to the low power generation operation.

(Embodiment 7)
Since this embodiment has basically the same configuration as each of the above-described embodiments and has the same function and effect, FIGS. 1 to 3 are applied mutatis mutandis. Hereinafter, the description will focus on the different parts. Depending on the type of stack 1, if the accumulated power generation time ttotal accumulated from the start of stack 1 installation becomes longer, or if the time tset from the installation time of stack 1 becomes longer, the stack Since the inside of 1 changes over time, there is a possibility that flooding may occur. In such a case, the control unit 700 obtains the cumulative power generation time ttotal and / or time tset of the stack 1, and when the cumulative power generation time ttotal and time tset become longer, the control unit 700 depends on the length of the cumulative power generation time ttotal and / or time tset. Thus, the first predetermined time t1 is shortened and the second predetermined time t2 is extended. Thereby, the flooding suppression power generation process is executed at an early stage. In addition, the flooding suppression power generation process is executed for a long time within the specified time. Therefore, the inside of the stack 1 can be maintained in an appropriate wet state. However, even if the flooding suppression power generation process is performed continuously for a long time, the inside of the stack 1 may be excessively wetted. Therefore, the second predetermined time t2 that is the execution time of the flooding suppression power generation process is a predetermined time (for example, Within 15 minutes).

(Embodiment 8)
Since this embodiment has basically the same configuration as each of the above-described embodiments and has the same function and effect, FIGS. 1 to 3 are applied mutatis mutandis. Hereinafter, the description will focus on the different parts. When the first predetermined time t1 has elapsed, the high-power generation operation that constitutes the flooding suppression power generation process can be performed intermittently. That is, a flooding suppression power generation process is performed in which the sixth predetermined time Δt6 (for example, 5 minutes) high power generation operation and the seventh predetermined time Δt7 (for example, 5 minutes) low power generation operation are alternately repeated a plurality of times. Can do. In this case, since the gas flow rate changes intermittently inside the stack 1, it is possible to contribute to moving the liquid phase water that is difficult to take out to the outside of the stack 1. Δt6 and / or Δt7 can be corrected according to the accumulated power generation time ttotal, the power generation conditions of the low power generation operation, and the like.

(Embodiment 9)
Since this embodiment has basically the same configuration as each of the above-described embodiments and has the same function and effect, FIGS. 1 to 3 are applied mutatis mutandis. Hereinafter, the description will focus on the different parts. FIG. 4 shows an example of a flowchart executed by the CPU 71 of the control unit 700. The flowchart is not limited to this. In this case, the first predetermined time t1 related to the low output power generation operation is set long, and the third predetermined time t3 related to the high output power generation operation ends within the first predetermined time t1 (t1> t3). . If the current operation state is the first high-output power generation operation or the second high-output power generation operation, the flag H is set. First, the current power generation state of the stack 1 is read (step S102). Next, it is determined whether or not the flag H is set, that is, whether or not the current operation state is a low output power generation operation or a high output power generation operation (step S104). If the flag H is not set (NO in step S104), it is determined whether or not the continuous execution time of the low-output power generation operation continues for a first predetermined time (for example, 5 minutes) (step S106). If the continuous execution time of the low output power generation operation continues for the first predetermined time (YES in step S106), the continuity of the low output power generation operation is determined to some extent, so the start time of the low output power generation operation is taken as the starting point. Then, measurement of the first predetermined time t1 is started (step S110). It is determined whether or not the first predetermined time t1 has elapsed (step S112).

  As a result of the determination in step S112, if the end of the first predetermined time t1 has passed (YES in step S112), the measurement of the first predetermined time t1 is reset and returned to 0 (step S114). Further, a residual moisture estimated value α in the continuous operation of the low output power generation operation is obtained (step S116). Further, a second predetermined time t2 is obtained from a map or an arithmetic expression based on the moisture residual estimated value α (step S118). Next, flooding suppression power generation processing is started (step S120). In this case, the stack 1 is controlled so that the power generation operation is performed while suppressing a decrease in the anode gas utilization rate and the cathode gas utilization rate with respect to the low-output power generation operation. That is, the control unit 700 outputs a command to maintain the anode gas utilization rate and the cathode gas utilization rate for the low-output power generation operation to the system. Measurement of the second predetermined time t2 is started (step S122).

  According to the flooding-suppressing power generation processing, in order to suppress fluctuations in the anode gas utilization rate and the cathode gas utilization rate for the low-power power generation operation, surplus power more than the power consumed by the power load 49x is basically stacked. Is likely to occur. For this reason, surplus power processing is executed (step S124). Specifically, at least one of a power storage operation in which the switching element 79a is turned on to store surplus power in the power storage element 79 and a heat storage operation in which the heater 63 is turned on to accumulate hot water energy in the hot water storage tank 85 is executed. To do. In particular, when surplus power is consumed by turning on the heater 63, if the control is performed so as to raise the temperature for collecting the hot water storage, the water temperature in the circulation passage 60 rises and the temperature of the stack 1 can be raised. It is possible to contribute to shifting the inside of the battery in the drying direction, and it is advantageous for preventing excessive flooding by using surplus power. Further, in the flooding suppression power generation process, the opening degree of the bypass valve 59 is controlled, the cathode gas flow rate that causes the humidifier 50 to bypass the bypass route 58 is increased, and the cathode gas flow rate that flows through the humidification path 50a of the humidifier 50 is increased. It is preferable to reduce. Furthermore, in the flooding suppression power generation process, the opening degree of the bypass valve 57 is controlled, the cathode gas flow rate that causes the humidifier 50 to bypass the bypass circuit 56 is increased, and the cathode off-gas flow rate that flows through the moisture absorption path 50 b of the humidifier 50. Is preferably reduced. Thereby, the humidification capability of the humidifier 50 is lowered. For this reason, the humidity of the cathode gas supplied to the cathode electrode 11 is lowered.

  If the end of the second predetermined time t2 has not elapsed, the flooding suppression power generation process is continued (NO in step S126). If the end of the second predetermined time t2 has elapsed (YES in step S126), it is estimated that the inside of the stack 1 has been appropriately wetted, and the flooding suppression power generation process is terminated (step S128) and the second predetermined time is reached. The measurement at time t2 is reset to 0, and the process returns to the main routine. When the low output power generation operation is continued again, the system is controlled through steps S102, S104, S106, S108 and the like.

  If the end of the first predetermined time t1 has not elapsed as a result of the determination in step S112 (NO in step S112). Wait for a second predetermined time (for example, 30 seconds) (step S140). It is determined whether the low-output power generation operation is still continued (step S142). If the low output power generation operation is continued (YES in step S142), since the operation continuity of the low output power generation operation is high, the measurement of the first predetermined time t1 is continued. If the low output power generation operation is not continued (NO in step S142), it is determined whether the first high output power generation operation or the second high output power generation operation is currently performed. That is, it is determined whether or not the flag H is currently set (step S144). If the flag H is not set (NO in step S144), the process returns to the main routine. If the flag H is set (YES in step S144), the first high-output power generation operation or the second high-output power generation operation is performed, and excess water inside the stack 1 is taken out of the stack 1. The control unit 700 starts measuring the third predetermined time t3 that is the execution time of the high-output power generation operation (step S146). As long as the first high-output power generation operation or the high-output power generation operation is continued (NO in step S148), the process returns to the main routine, and proceeds again to YES and S148 in steps S102, S104, and S170, and at a third predetermined time. Measurement of t3 is continued.

  As a result of the determination in step S148, if the first high-output power generation operation or the second high-output power generation operation is completed and the flag H is off (YES in step S148), the first predetermined time t1 is calculated from the start time of calculation. An elapsed time tx until the start of the first high output power generation operation or the second high output power generation operation is obtained (step S150). The elapsed time tx is the time when the first high-power generation operation or the second high-output power generation operation that exhibits the action of taking out the water inside the stack 1 is started until the end of the first predetermined time t1 ends. Is a parameter provided to clarify the above. Here, when the first high-output power generation operation or the second high-output power generation operation is executed in the second half of the period within the first predetermined time t1, there is a high probability that the water in the stack 1 is taken out to the outside. It can be said that the stack 1 is in a moderate wet state or dry state. On the other hand, when the first high output power generation operation or the second high output power generation operation is executed in the initial period within the first predetermined time t1, the flooding suppression effect based on the high output power generation operation performed in the initial stage is performed. May have disappeared.

  Furthermore, the accumulated power generation time ttotal of the stack 1 after the stack 1 is installed at the installation location is obtained (step S152). Then, based on the execution time ta and the elapsed time tx of the high-output power generation operation, the control unit 700 further considers the accumulated power generation time ttotal and the correction value Δt10 related to the first predetermined time t1 and the second predetermined time. A correction value Δt20 relating to t2 is obtained from a map or an arithmetic expression (step S154). Furthermore, the power generation output value Pw of the first high power power generation operation or the second high power power generation operation is obtained. The map or the arithmetic expression defines the correction value Δt10 and the correction value Δt20 based on the execution time ta, the elapsed time tx, the accumulated power generation time ttotal, and the power generation output value Pw. Here, if the execution time ta is long within the specified time, it is considered that the amount of water taken out from the stack 1 is large. If the elapsed time tx is long, flooding is unlikely to occur at the present time. If the cumulative power generation time ttotal is long, flooding is likely to occur due to secular change. If the power generation output value Pw is large, it is basically considered that the amount of water taken out from the stack 1 is large. A map or an arithmetic expression is set in consideration of these.

  Further, the control unit 700 adds the correction value Δt10 to the first predetermined time t1 and extends the length of the first predetermined time t1 under the condition that the end of the first predetermined time t1 has not yet ended. Correct as follows. Thus, the first correction is executed in which the end of the first predetermined time t1 is corrected to be extended. Also, a second correction is performed to reduce the length of the second predetermined time t2 by subtracting the correction value Δt20 from the second predetermined time t2 (step S156). Therefore, thereafter, the system is controlled based on the first predetermined time t1 corrected for extension and the second predetermined time t2 corrected for shortening. Thereafter, the third predetermined time t3 is reset, and the process returns to the main routine. One of the first correction and the second correction may be performed.

  Note that, as a result of the determination in step S104, if the current time is the first high-output power generation operation or the high-low power generation operation, the flag H is set, so the process proceeds from step S104 to step S170, and the third predetermined time t3 is being measured. If the third predetermined time t3 is being measured (YES in step S170), the process proceeds to step S148. If the measurement is not being performed for the third predetermined time t3 (NO in step S160), the process returns to the main routine. The flag H, the first predetermined time t1, the second predetermined time t2, and the third predetermined time t3 are reset when they are inappropriate.

  In the present embodiment, when the first high-output power generation operation and / or the second high-output power generation operation is executed a plurality of times within the first predetermined time t1, the measured value and correction value Δt10 of the third predetermined time t3, Δt20 takes this into account.

  As described above, also in the present embodiment, when the low output continuous execution time of the low output power generation operation passes the end of the first predetermined time t1, the control unit 700 generates the generated power of the low output power generation operation at the first predetermined time t1. A residual moisture estimated value α is obtained, and a second predetermined time t2 during which flooding suppression power generation processing is executed is obtained from a map or an arithmetic expression based on the residual moisture estimated value α. Then, the control unit 700 executes the flooding suppression power generation process for the second predetermined time t2. If 2nd predetermined time t2 passes, the control part 700 will be able to perform a low output electric power generation operation again according to a user's request | requirement.

  Furthermore, also in the present embodiment, the control unit 700 obtains the execution time ta of the high-output power generation operation and the elapsed time tx until the high-output power generation operation is started from the start time of the first predetermined time t1. Then, the control unit 700 corrects the first predetermined time t1 and the second predetermined time t2 in consideration of the accumulated power generation time ttotal based on the execution time ta and the elapsed time tx of the high output power generation operation. For example, the longer the execution time ta of the high-output power generation operation or the longer the elapsed time tx, the higher the probability that the water inside the stack 1 is taken out of the stack 1. Correction is made to extend the first predetermined time t1 being measured, or correction is made to shorten the second predetermined time t2.

(Embodiment 10)
Since the present embodiment has basically the same configuration as each of the embodiments described above and has the same function and effect, FIGS. 1 to 4 can be applied mutatis mutandis. Hereinafter, the description will focus on the different parts. FIG. 5 shows a connection portion between the stack 1 and the commercial power source 49. As shown in FIG. 5, the commercial power source 49 is electrically connected to a household or business power load 49x via a breaker 49e. Between the stack 1 and the commercial power source 49, a switching element 154, a power conditioner 120, and a control board 130 electrically connected to the power conditioner 120 are provided. The power conditioner 120 includes a switching element 151, a switching element 152, a heater drive circuit 630 for operating the heater 63, a heater switching element 153 for switching between power supply and interruption to the heater 63 and the heater drive circuit 630, A rectifier circuit 16w provided between the commercial power supply 49 and the auxiliary machine for converting AC power of commercial power into DC power, and DC power generated by the stack 1 is converted into DC power having different voltages. DC / DC converter (DC / DC converter) 17w, and DC / AC inverter 18w (DC / AC converter) for converting DC generated power converted by the DC / DC converter 17w into AC power, And a control circuit 19w for a power conditioner.

  The power supply line 25m for supplying power to the heater 63 is connected to wirings 180 and 182 between the DC / AC inverter 18w and the first switching element 151 so that AC power can be supplied to the heater 63. The power supply line 16m connected to the rectifier circuit 16w is connected to the wirings 160 and 162 on the input side of the switching element 151. The switching element 151 is a switching element because it is interconnected with the commercial power source 49. The first switching element 151 is configured by arranging switches 151a and 151c in series.

  Further, the control board 130 has an auxiliary machine drive power supply 131 that mounts a drive circuit for operating the auxiliary machine, and an auxiliary machine control circuit 132 for controlling the auxiliary machine via the auxiliary machine drive power supply 131. A power supply line 135m for supplying power to the auxiliary drive power supply 131 is connected to the commutator 174 on the wirings 170 and 172 between the DC / DC converter 17w and the DC / AC inverter 18w so that direct current power can be supplied to the auxiliary drive power supply 131. Connected through.

  Auxiliary equipment is equipment that performs operations associated with power generation operation of the system. Accordingly, the auxiliary machines include the pumps 23, 37, 42, 61, 53, 82, 521, valves 22, 25v, 28, 30, 40a, 90, 54, 57, 59, radiator fan 89a shown in FIG. Etc. Each of these has a drive circuit. However, for convenience, in the present specification, these are summarized as auxiliary machines. The auxiliary machine is driven by DC power.

  As can be understood from FIG. 4, the generated power (direct current) of the stack 1 is voltage-adjusted by the DC / DC converter 17w and then fed to the auxiliary drive power supply 131 via the feed line 135m. A power storage element 79 is connected to the auxiliary drive power supply 131 via a switching element 79a and a power storage circuit 79e.

  As described above, according to the flooding-suppressing power generation processing, the flow rate per unit time of the anode gas supplied to the anode electrode 10 and the flow rate per unit time of the cathode gas supplied to the cathode electrode 11 are reduced from the low power generation operation. Therefore, surplus generated power is more easily generated than the power consumed by the power load 49x. Here, according to the flooding suppression power generation process, it is necessary to increase the flow rates of the anode gas and the cathode gas and also increase the supply flow rate of the reformed water to the reforming unit 25, such as pumps 23, 42, 53, and 37. Since the driving amount (rotation speed) of the auxiliary machine is increased as compared with the low output power generation operation, the power consumption of the auxiliary machine is increased as compared with the low output power generation operation. In this regard, according to the present embodiment, the flooding-suppressing power generation process generates surplus generated power, but the surplus generated power is used preferentially as drive power for auxiliary equipment such as pumps 23, 42, 53, and 37. It can be consumed, and the surplus power is effectively utilized. In particular, if the switching elements 153 and 79a are turned off, it can be preferentially consumed as driving power for the auxiliary machine. Furthermore, the surplus power can be stored as heat energy of hot water that is consumed as heat of the heater 63 and stored in the hot water tank 85 when the switching element 153 is turned on. Or, secondarily, the storage element 79 can be stored as electrical energy by turning on the switching element 79a.

(Other)
The present invention is not limited to the embodiment described above and shown in the drawings, but can be applied to any system in which flooding is likely to occur due to low-output power generation operation. it can. The system is not limited to the structure shown in FIG. A storage unit for storing the anode gas may be provided without mounting the reformer, and the anode gas may be supplied from the storage unit to the anode electrode 10 of the stack 1. The humidifier 50 may be abolished. The control unit 700 obtains a moisture residual estimated value α related to the generated power in the low power generation operation at the first predetermined time t1, and based on the moisture residual estimated value α, the second predetermined time t2 during which the flooding suppression power generation process is executed. It may be determined from a map or an arithmetic expression. Alternatively, the second predetermined time t2 may be simply obtained from the length of the first predetermined time t1 so that the relationship of t1> t2 is established.

The following technical idea can also be grasped from the description of the present specification.
[Additional Item 1] A fuel cell having an anode electrode to which an anode gas is supplied and a cathode electrode to which a cathode gas is supplied and generating power with the anode gas and the cathode gas, and supplying the anode gas to the anode electrode of the fuel cell A fuel cell system comprising: an anode gas supply system for performing the operation; a cathode gas supply system for supplying a cathode gas to the cathode electrode of the fuel cell; and a controller for controlling the anode gas supply system and the cathode gas supply system. The fuel cell is generated.

  The present invention can be used in, for example, fuel cell systems for stationary use, electronic equipment use, electrical equipment use, vehicle use, portable use, and portable use.

  1 is a stack (fuel cell), 10 is an anode electrode, 11 is a cathode electrode, 12 is an ion conductive membrane, 13 is a refrigerant passage, 2 is an anode gas supply system, 20 is an anode gas supply passage, 21 is an anode gas supply source, 22 is an anode gas valve, 23 is an anode gas pump, 24 is a reformer, 25 is a reforming section, 26 is a combustion section, 29 is an anode off-gas passage, 28 is an inlet valve, 34 is a reforming water system, 35 is a tank, 37 is Water pump, 38 water valve, 39 evaporating section, 42 pump, 47 breaker, 48 inverter, 49 commercial power supply, 5 cathode gas supply system, 50 humidifier, 52 cathode gas supply passage, 53 Is a cathode gas pump, 54 is an inlet valve, 56 is a bypass, 57 is a bypass valve, 6 is a cooling system, 60 is a circulation passage, 61 is a refrigerant pump, 62 is a temperature sensor, 63 Heater, 700 is a control unit, 79 is a power storage element (energy storage unit), 9 is a water purification system, 90 is a valve, 91 is a first water purification unit, 92 is a second water purification unit, 8 is a hot water storage system, and 80 is A hot water storage passage, 82 is a pump, and 85 is a hot water storage tank (energy storage unit).

Claims (6)

A fuel cell having an anode electrode supplied with an anode gas and a cathode electrode supplied with a cathode gas;
An anode gas supply system for supplying an anode gas to the anode electrode of the fuel cell;
A cathode gas supply system for supplying a cathode gas to the cathode electrode of the fuel cell;
A control unit for controlling the anode gas supply system and the cathode gas supply system,
When the low output continuous execution time of the low output power generation operation that is likely to generate flooding inside the fuel cell exceeds the first predetermined time t1 or more, the control unit A fuel cell system that performs a first control to execute a flooding suppression power generation process that suppresses flooding for a second predetermined time t2 (t2 <t1) while performing a power generation operation so as to suppress a decrease in anode gas utilization rate.   2. The fuel cell system according to claim 1, further comprising: an energy storage unit that generates surplus generated power in the flooding suppression power generation process and stores the generated surplus generated power as thermal energy or electrical energy. 3. The high output power generation operation for generating power at an output higher than the low output power generation operation before the low output continuous execution time has passed the first predetermined time t1 in the third predetermined time t3 (t1). > T3) When executed above, and then return to the low power generation operation,
The control unit corrects the first predetermined time t1 and / or the second predetermined time t2 based on an execution time ta (t1> ta ≧ t4) of the high-output power generation operation. 3. The high-power power generation operation for generating power at a higher output than the low-power power generation operation before the first predetermined time t1 elapses before the low-power power generation operation time exceeds a third predetermined time t3 (t1). > T3) When executed, and then return to the low power generation operation,
The control unit resets the low output continuous execution time and starts re-measurement of the low output continuous execution time. In Claim 1 or 2, before the said low output continuous execution time passes the said 1st predetermined time t1, the high output electric power generation operation | movement which generates electric power with a higher output than the said low output electric power generation operation is more than 4th predetermined time t4 ( t1> t4) is executed and then returns to the low power generation operation,
The control unit includes an execution time ta (t1> ta ≧ t4) of the high output power generation operation and an elapsed time from the start of the low output continuous execution time to the start of the high output power generation operation. Based on this, the fuel cell system corrects the first predetermined time t1 and / or the second predetermined time t2.   6. The anode gas supply system according to claim 1, wherein the anode gas supply system reforms the raw material to generate anode gas to be supplied to the fuel cell, and reforms the reformer. A fuel cell system comprising: a combustion section that heats to a temperature range suitable for a reaction; and an anode offgas passage that supplies anode offgas discharged from an anode electrode of the fuel cell to the combustion section and burns the combustion section.

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