JP2012038538A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of preventing such a failure that the system shuts down shortly after the startup.SOLUTION: A fuel cell system comprises: a condenser 74 which generates condensed water by cooling steam-containing gas; a stored hot water channel 71 which supplies water in a hot water storage tank 70 to the condenser 74 as cooling water; a stored hot water conveyance source 72 which supplies water in the hot water storage tank 70 to the stored hot water channel 71 as the cooling water to cool the steam-containing gas in the condenser 74; a reforming water tank 44 to which the condensed water generated by the condenser 74 is recovered; a reforming water conveyance source 42 which supplies the water in the reforming water tank 44 to a reformer 2; and a control unit 100 which outputs a signal to allow activation of the system if a condition that a water level in the reforming water tank 44 is equal to or higher than a predetermined water level is met when starting up the system.

Description

  The present invention relates to a fuel cell system in which water vapor-containing gas is cooled in a condenser to form condensed water, and the condensed water is stored as reformed water in a reformed water tank.

  The fuel cell system stores a reformer that reforms a fuel raw material with reformed water to generate an anode gas, a fuel cell that generates power using the anode gas and the cathode gas, and hot water heated by the exhaust heat of the system. A hot water storage tank, a condenser that cools the steam-containing gas generated by the operation of the system to generate condensed water, a hot water storage passage that supplies the hot water from the hot water tank to the condenser as cooling water, and hot water stored in the hot water tank A hot water supply source that cools the water vapor-containing gas in the condenser by supplying it as cooling water to the passage, and a reforming water tank that collects the condensed water generated by the condenser and stores it as liquid phase reforming water. (Patent Documents 1 and 2)

JP 2008-234869 A JP 2007-280970 A

  The above-mentioned patent documents do not mention a starting method after the system is stopped due to lack of reforming water. Therefore, when the system is started after the system is stopped due to a shortage of reforming water, the system is started and the power generation operation is executed for a short time, but the power generation operation of the system may be stopped again due to the shortage of water. The present invention has been made in view of the above-described circumstances, and even if the system is started, there is no risk of running out of reforming water, so that the operation of the system is stopped in a short time after startup due to water drainage. It is an object of the present invention to provide a fuel cell system capable of suppressing problems.

  The present invention according to claim 1 is a reactor that reforms a fuel raw material with reforming water to generate anode gas, a fuel cell that generates electricity using anode gas and cathode gas, and heated by exhaust heat of the system. A hot water storage tank for storing hot water, a condenser for cooling the steam-containing gas generated during the operation of the system to generate condensed water, a hot water storage passage for supplying the water in the hot water storage tank as cooling water, and a hot water storage tank Supply of hot water to the hot water storage passage as cooling water to cool the steam-containing gas in the condenser, and reforming that collects the condensed water generated by the condenser and stores it as liquid reforming water A water tank, a sensor for detecting the level of the reforming water stored in the reforming water tank, a reforming water conveyance source for supplying the reforming water stored in the reforming water tank to the reformer, When starting up the system, When at least one of the first condition that the position is equal to or higher than the predetermined water level and the second condition that the amount of water below the first predetermined temperature in the hot water tank is equal to or higher than the predetermined amount is satisfied, the system is A fuel cell system including a control unit that permits activation. In this case, even if the system is started, it is estimated that there is no possibility that the reformed water is insufficient.

  According to a second aspect of the present invention, there is provided a reformer that reforms a fuel raw material with reforming water to generate an anode gas, a fuel cell that generates electric power using the anode gas and the cathode gas, and heated by exhaust heat of the system. A hot water storage tank for storing hot water, a condenser for cooling the steam-containing gas generated during the operation of the system to generate condensed water, a hot water storage passage for supplying the water in the hot water tank to the condenser as cooling water, and hot water storage A hot water supply source for cooling the water vapor-containing gas of the condenser by supplying the tank water as cooling water to the hot water storage passage, and cooling the water in the passage portion upstream of the condenser in the hot water storage passage using the outside air. Detects the level of reforming water stored in the reforming water tank, the reforming water tank that collects the condensed water generated by the condenser and stores it as liquid phase reforming water Sensor and reforming water tank The first condition that the water level of the reforming water tank is equal to or higher than a predetermined water level when starting the system and the reforming water transport source that supplies the reforming water to the reformer. The system is activated when at least one of the second condition that the amount of water below the predetermined temperature is equal to or higher than the predetermined amount and the third condition that the temperature of the outside air is equal to or lower than the second predetermined temperature is satisfied. A fuel cell system including a control unit to be permitted. In this case, even if the system is started, it is estimated that there is no possibility that the reformed water is insufficient.

  Preferably, when starting the system, when the water level of the reforming water tank is less than a predetermined water level, when it is determined that the condensed water generation capability in the condenser is secured, the relaxed first condition that relaxes the first condition When the water level of the reforming water tank is satisfied, the control unit allows the system to be activated. This is because even if the system is started, it is presumed that there is no risk of the reforming water being insufficient.

  According to a fourth aspect of the present invention, a reformer that reforms a fuel raw material with reforming water to generate anode gas, a fuel cell that generates power using the anode gas and the cathode gas, and heated by the exhaust heat of the system A hot water storage tank for storing hot water, a condenser for cooling the steam-containing gas generated during the operation of the system to generate condensed water, a hot water storage passage for supplying the water in the hot water storage tank as cooling water, and a hot water storage tank Supply of hot water to the hot water storage passage as cooling water to cool the steam-containing gas in the condenser, and reforming that collects the condensed water generated by the condenser and stores it as liquid reforming water A water tank, a sensor for detecting the level of the reforming water stored in the reforming water tank, a reforming water conveyance source for supplying the reforming water stored in the reforming water tank to the reformer, When starting up the system, The amount is a fuel cell system and a control unit for activating allowed the system based on the amount of the first predetermined temperature or less of water out of the hot water storage tank. In this case, even if the system is started, it is estimated that there is no possibility that the reformed water is insufficient.

  According to a fifth aspect of the present invention, there is provided a reformer for reforming a fuel raw material with reforming water to generate an anode gas, a fuel cell for generating electric power with the anode gas and the cathode gas, and heating with exhaust heat of the system. A hot water storage tank for storing hot water, a condenser for cooling the steam-containing gas generated during the operation of the system to generate condensed water, a hot water storage passage for supplying the water in the hot water tank to the condenser as cooling water, and hot water storage A hot water supply source for cooling the water vapor-containing gas of the condenser by supplying the tank water as cooling water to the hot water storage passage, and cooling the water in the passage portion upstream of the condenser in the hot water storage passage using the outside air. Detects the level of reforming water stored in the reforming water tank, the reforming water tank that collects the condensed water generated by the condenser and stores it as liquid phase reforming water A sensor and the modified water tank The reforming water transport source that supplies the reforming water stored in the reformer and the amount of water in the reforming water tank, the amount of water below the first predetermined temperature in the hot water storage tank, It is a fuel cell system provided with the control part which permits starting of a system based on the temperature of this. In this case, even if the system is started, it is estimated that there is no possibility that the reformed water is insufficient.

  Preferably, when starting the system, the control unit uses the energy for starting the system for power generation operation, rather than the start / stop energy obtained by adding the start energy used for starting the system and the stop energy used for stopping the system. The system is allowed to start when the generation operation time exceeding the saving amount is obtained.

  The reformer reforms the fuel material with reforming water (gas phase and / or liquid phase reforming water) to generate anode gas. The fuel cell generates power with anode gas and cathode gas. The hot water storage tank stores hot water heated by the exhaust heat of the system. The condenser cools the steam-containing gas generated during the operation of the system and generates condensed water. Examples of such water vapor-containing gas include at least one of anode gas, anode off gas, cathode gas, cathode off gas, and combustion exhaust gas. The condensed water generated by the condenser is stored in the reformed water tank as liquid phase reformed water. The sensor directly or indirectly detects the water level of the reforming water stored in the reforming water tank. Indirect detection includes the case where the water level is detected by detecting a physical quantity related to the amount of reformed water stored. When the reforming water conveyance source is driven, the reforming water stored in the reforming water tank is supplied to the reformer and used for the reforming reaction.

  In starting the system, the control unit outputs a signal for allowing the system to start when the first condition that the water level of the reforming water tank is equal to or higher than a predetermined water level is satisfied. In this case, since the amount of water in the reformed water tank (hereinafter also referred to as a tank) is secured, it is possible to suppress the stop immediately after the system is started. Predetermined water level means the water level in the tank so that the system does not stop immediately after the system starts up, and depending on the type of system and the installation environment of the system, the system is a water self-supporting type It is appropriately set depending on whether or not. When the first condition that the water level of the tank is equal to or higher than the predetermined water level is not satisfied, the activation of the system is limited. Furthermore, even if the system is started, the power generation of the system may be stopped immediately due to the lack of reforming water. For this reason, the control unit does not permit activation of the system.

  It is energetically disadvantageous to shut down the system in a short time due to water drainage after the system is started. That is, it becomes a factor which increases the running cost and fuel cost of the system, which is not preferable. Therefore, according to the fuel cell system of the present invention, the control unit outputs a signal for permitting activation of the system when there is no shortage of reforming water even when the system is activated. In this case, it is possible to prevent the system from stopping in a short time after activation. In particular, in the case of a water self-sustained operation type system that suppresses or eliminates the operation of replenishing water as reformed water over a long period of time, there is a possibility that the reformed water stored in the tank may be limited. It is valid. Note that the present invention is also effective in the case of a system that performs an operation of replenishing water as reformed water.

  According to the present invention, even if the system is started, it is presumed that there is no risk of running out of the reforming water. A fuel cell system can be provided.

It is a figure which shows the outline | summary of a system. It is a figure which shows the outline | summary of the tank mounted in the system. It is a flowchart which a control part performs. The characteristic example at the time of implementing control shown in Drawing 3 is shown typically. It is a flowchart which concerns on another embodiment and a control part performs. 10 is a flowchart executed by a control unit according to another embodiment. It is a graph which shows the change of the temperature on a reference day. It is a graph which shows the fluctuation | variation of the water balance of a tank when producing | generating a fuel cell with the generated electric power W1 in a reference | standard day. It is a graph which shows the fluctuation | variation of the water balance of a tank when the fuel cell is generating with the generated electric power W1. It is a graph which shows the fluctuation | variation of the water balance of a tank when the fuel cell is generating with the generated electric power W1. It is a graph which shows the fluctuation | variation of the water balance of a tank when operating the system by the power generation stop mode. It is a graph which shows the relationship of the water balance of a tank when starting a system. It is an outline figure showing an inside of a power generation module concerning an example of an application form.

  According to one aspect of the present invention, when the system is started, the water sent from the hot water storage tank to the condenser via the hot water storage passage can exhibit a condensing action in the condenser, and the first predetermined temperature or lower in the hot water storage tank. When the second condition that the amount of water is equal to or greater than the predetermined amount is further satisfied, the control unit preferably allows the system to be activated. This is because when both the first condition and the second condition are satisfied, the amount of condensed water generated in the condenser is further increased, and the water level in the tank is more easily secured. The first predetermined temperature is preferably a temperature at which the steam-containing gas can be cooled and condensed water can be generated from the steam-containing gas in the condenser, and is lower than the temperature of the steam-containing gas. For example, 35, 30 degreeC, or 25 degreeC is illustrated.

  According to one aspect of the present invention, there is provided a radiator device that exhibits a cooling action by using outside air for water in a passage portion upstream of a condenser in a hot water storage passage. In this case, when the system is started, when the third condition that the outside air is equal to or lower than the second predetermined temperature is further satisfied so that the radiator device can exert a cooling action for cooling the water in the passage portion, the control unit It is preferable to allow the system to be activated. This is because when the first condition and the third condition are satisfied, the amount of condensed water generated in the condenser is further increased, and the water level in the tank is more easily secured. The second predetermined temperature means a temperature at which the water in the passage portion upstream of the condenser in the hot water storage passage can be cooled with outside air, and is lower than the water in the passage portion. For example, 38, 35 degreeC, 30 degreeC, or 25 degreeC is illustrated.

  According to one aspect of the present invention, when the system is started, even when the water level of the reforming water tank is less than the predetermined water level, when it is determined that the condensed water generation capability in the condenser is ensured, When the water level of the reforming water tank satisfies the relaxed first condition obtained by relaxing the first condition, the control unit permits the system to be activated. Moreover, when it determines with the condensed water production | generation capability in a condenser not being ensured, a control part does not permit starting of a system irrespective of satisfaction of 1st relaxation conditions. The reason for this is that when it is determined that the condensed water generation capability of the condenser is ensured, even if the water level of the reforming water tank is less than the predetermined water level, the system shutdown can be suppressed.

  According to one aspect of the present invention, it is preferable that the sensor detects a high water level and a middle water level that are located from the upper part to the lower part in the direction of gravity in the tank. In this case, it is preferable that the control unit executes the normal power generation mode when the water level of the tank is higher than the high water level. It is preferable to execute an output restriction mode in which the output restriction is applied to the maximum power generation output of the fuel cell when the water level of the tank is lower than the high water level and higher than the middle water level. In starting the system, it is preferable that the system is permitted to start when the water level of the tank is equal to or higher than the middle water level, and that the system is not permitted to start when the water level of the reforming water tank is less than the middle water level. This is because, if the water level of the tank is equal to or higher than the middle water level, even if the system is started, it is possible to prevent the power generation operation of the system from being stopped due to the lack of water in the tank. According to one aspect of the present invention, the control unit, after allowing the system to start, supplies the fuel raw material to the reformer and drives the reforming water conveyance source to reform the reforming water in the tank. It is preferable to supply to the vessel. As a result, the system starts up.

(Embodiment 1)
FIG. 1 shows an overview of the system. This is applied to a solid oxide fuel cell. The system basically includes a solid oxide fuel cell 1, a reformer 2, a control unit 100, and a housing 9. Further, the fuel cell system includes a reforming water system 4, a fuel material supply system 5, a cathode gas supply thread 6, and a hot water storage system 7 inside the housing 9. In FIG. 1, the fuel cell 1 is schematically shown. The system is a water self-supporting type in which power generation operation is performed without supplying water to the tank 44 for a long period of time or semipermanently. As shown in FIG. 1, the reformer 2 includes an evaporation unit 20 and a reforming unit 22 to which a fuel material is supplied. The evaporator 20 vaporizes the liquid phase reformed water supplied from the reforming water system 4 to the evaporator 20. The reforming unit 22 is provided downstream of the evaporation unit 20 and steam-reforms the fuel material with the steam generated by the evaporation unit 20 to generate anode gas. The anode gas is hydrogen gas or hydrogen-containing gas. The housing 9 has an outside air intake port 92 and a discharge port 93 that allow the storage chamber 91 of the housing 9 to communicate with the outside air. The power generation module 3 is housed inside the housing 9 and has a container-like heat insulating portion 30 formed of a heat insulating material that forms the power generation chamber 32, and the fuel cell 1 and the modified battery are formed inside the heat insulating portion 30. The mass device 2 is formed through the combustion space 23. In the power generation module 3, the reformer 2 (the reforming unit 22 and the evaporation unit 20) is disposed on the upper side of the fuel cell 1. In the power generation module 3, a combustion space 23 is formed between the fuel cell 1 and the reformer 2 (the reforming unit 22 and the evaporation unit 20). In particular, a combustion space 23 is formed between the upper part of the fuel cell 1 and the lower part of the reformer 2 (the reforming part 22 and the evaporation part 20). The anode off gas discharged from the anode of the fuel cell 1 is discharged into the combustion space 23. The anode off gas means a gas discharged from the anode of the fuel cell 1 and contains unreacted hydrogen (combustible component) and can be combusted. The cathode off gas contains unreacted oxygen. The anode off-gas discharged to the combustion space 23 is burned by a cathode gas containing oxygen or a cathode off-gas (corresponding to combustion air) to form a combustion flame 24 in the combustion space 23. The gas that forms the combustion flame 24 in the combustion space 23 becomes combustion exhaust gas. The combustion flame 24 in the combustion space 23 heats both the reforming unit 22 and the evaporation unit 20 and maintains the temperature of the reforming unit 22 in the reforming reaction temperature region.

  As shown in FIG. 1, the reforming water system 4 supplies reforming water that is consumed as water vapor in steam reforming in the reforming unit 22 to the reforming unit 22. 2, a reforming water passage 41, a reforming water pump 42 (reforming water transport source), and a water supply valve 43. The water purifier 40 includes a water purification material 40a such as an ion exchange resin that can purify water. In the reforming water passage 41, a tank 44, a reforming water pump 42, and a water supply valve 43 are provided.

  As shown in FIG. 1, the fuel material supply system 5 includes a fuel material supply passage 51 connected to a fuel source 50 for supplying a fuel material such as a hydrocarbon system to the reformer 2, an inlet valve 52, a flow meter. 53, a desulfurizer 54, and a fuel feed pump 55 (fuel feed transfer source). In the fuel material supply passage 51, an inlet valve 52, a flow meter 53, a desulfurizer 54, and a fuel material pump 55 are provided in this order. However, the order is not limited to this. The cathode gas supply yarn 6 includes a cathode gas supply passage 60 for supplying a cathode gas, which is air, to the cathode 12 of the fuel cell 1, a dust filter 61, a cathode gas pump 62 (cathode gas transport source), and a flow meter 63. Have. Although the dust filter 61, the cathode gas pump 62, and the flow meter 63 are arranged in this order in the cathode gas supply passage 60, the order is not limited to this order. The dust filter 61 is disposed in the housing chamber 91 of the housing 9. When the cathode gas pump 62 is driven, outside air flows into the housing chamber 91 from the outside air inlet 92 and is supplied to the cathode 12 from the inlet of the fuel cell 1 as cathode gas through the dust filter 61 and the cathode gas supply passage 60.

  As shown in FIG. 1, the hot water storage system 7 includes a hot water storage tank 70, a hot water storage passage 71 that circulates through the condenser 74 and the hot water storage tank 70, a hot water storage pump 72 (hot water storage water conveyance source) provided in the hot water storage path 71, And a condenser 74. A water outlet 70 p is provided in the lower part of the hot water tank 70. A water inlet 70 i is provided at the upper part of the hot water tank 70. The hot water storage passage 71 has a forward path 71a from the water outlet 70p to the condenser 74 and a return path 71c from the condenser 74 to the water inlet 70i. When the hot water storage pump 72 is activated, water near the bottom of the hot water storage tank 72 is discharged from the outlet 70p, supplied to the condenser 74 from the forward passage 71a of the hot water storage passage 71, and heated by heat exchange with the exhaust gas in the condenser 74. The The heated water returns to the hot water tank 70 from the water inlet 70i through the return path 71c. Thereby, the hot water tank 70 stores hot water. In the hot water storage tank 70, a plurality of temperature sensors 70t are arranged along the height direction. When the hot water in the hot water storage tank 70 is taken out from the hot water supply passage 70h to the hot water consumption unit 70k, make-up water such as tap water is supplied from the supply passage 70w. Accordingly, the hot water tank 70 is set to be always full.

  A condenser 74 (corresponding to a heat exchanger) is provided in the vicinity of the power generation module 3. The condenser 74 has a gas passage 74g through which the combustion exhaust gas discharged from the power generation module 3 passes and a water passage 74w through which water in the hot water storage passage 71 of the hot water storage system 7 passes. The heat of the exhaust gas flowing through the gas passage 74g of the condenser 74 is transferred to the water passage 74w by heat exchange, and further transferred to the water in the hot water storage passage 71 of the hot water storage system 7. An exhaust passage 75 extends from the gas passage 74 g of the condenser 74 toward the exhaust port 76 of the housing 9. The exhaust gas in the power generation chamber 32 of the power generation module 3 is discharged from the exhaust port 76 via the gas passage 74g and the exhaust passage 75 of the condenser 74. A condensed water passage 77 extends from the gas passage 74 g of the condenser 74 toward the water purifier 40. This exhaust gas is a steam-containing gas. Therefore, the vapor-phase moisture contained in the exhaust gas is cooled by the water passage 74w in the gas passage 74g of the condenser 74 to generate condensed water. The condensed water is stored in the tank 44 from the condensed water passage 77 through the water purifier 40. The forward path 71a of the hot water storage passage 71 is provided with a radiator device 79 that functions as a cooling device capable of forcibly cooling the water in the forward path 71a. The radiator device 79 includes a radiator 79a having cooling fins and a heat radiation passage communicating with the forward path 71a, and a cooling fan 79c that blows air to the radiator 79a and actively cools the radiator 79a. The rotational speed of the cooling fan 79c may be fixed or variable. The radiator device 79 may be outside the housing 9, inside the housing 9, or inside an unillustrated housing that houses the hot water tank 70.

  When the system is started, the fuel material pump 55 is driven, and the fuel material is supplied to the fuel cell 1 through the desulfurizer 54, the fuel material supply passage 51, the evaporation unit 20, and the reforming unit 22, To the combustion space 23. Further, since the cathode gas pump 62 is driven, cathode gas (air) is supplied to the combustion space 23 as combustion air. As a result, the combustible fuel material is burned by the cathode gas (combustion air) in the combustion space 23, and a combustion flame 24 is formed in the combustion space 23. The combustion flame 24 heats the reforming unit 22 and the evaporation unit 20 to a high temperature, enables a reforming reaction, and warms up the fuel cell.

  Next, during the power generation operation of the fuel cell 1, the fuel material pump 55 is driven, and the fuel material is supplied to the evaporation unit 20 of the reformer 2 through the fuel material supply passage 51. Further, the reforming water pump 42 is driven, and the liquid phase reforming water in the tank 44 is supplied to the evaporation unit 20 through the reforming water passage 41. Here, since the evaporation unit 20 is heated, the evaporation unit 20 vaporizes the reformed water. The steam is supplied to the reforming unit 22. The reforming unit 22 steam reforms the fuel material to generate anode gas.

When the fuel raw material is methane-based, it is considered that the generation of the anode gas in the steam reforming is based on the following equation (1). In the solid oxide fuel cell 1, CO can be used as fuel in addition to H ₂ .
(1) ... CH ₄ + 2H ₂ O → 4H ₂ + CO ₂
CH ₄ + H ₂ O → 3H ₂ + CO
The generated anode gas is supplied to the inlet of the anode 11 of the fuel cell 1 through the anode gas passage 14 and the anode gas manifold 13 and used for power generation. Since the cathode gas pump 62 is driven, outside air outside the housing 9 is supplied as cathode gas to the inlet of the cathode 12 of the fuel cell 1 through the dust filter 61 and the cathode gas supply passage 60. Thereby, the fuel cell 1 generates electric power. In the power generation reaction, it is considered that the reaction (2) basically occurs at the anode 11 supplied with the hydrogen-containing gas. It is considered that the reaction (3) basically occurs at the cathode 12 to which oxygen is supplied. Oxygen ions (O ²⁻ ) generated at the cathode 12 conduct the electrolyte from the cathode 12 toward the anode 11.
(2) ... H ₂ + O ²⁻ → H ₂ O + 2e ⁻
When CO is contained, CO + O ²⁻ → CO ₂ + 2e ⁻
(3)... 1 / 2O ₂ + 2e ⁻ → O ²⁻
The anode off gas after the power generation reaction includes hydrogen that has not undergone the power generation reaction and unreacted fuel raw material (methane). The cathode off gas contains oxygen that has not reacted in the power generation reaction. The anode off-gas and the cathode off-gas are discharged into the combustion space 23 above the fuel cell 1 to form a combustion flame 24 in the combustion space 23. Since hydrogen and methane react with oxygen in the combustion reaction in the combustion flame 24, H ₂ O is generated by the combustion reaction. The combustion exhaust gas after combustion flows through the exhaust passage 75 through the gas passage 74g and the gas outlet 78 of the condenser 74, and is further discharged from the exhaust port 76 at the tip of the exhaust passage 75 to the outside of the housing 9. Here, the exhaust gas flowing through the gas passage 74g of the condenser 74 contains moisture. This water is excessively added to the amount of reforming water necessary for the reforming reaction (usually 2.5 or more (S more than the amount of water necessary for improving the coking of the reforming catalyst and the fuel cell catalyst). / C) is poured.), including of _{H 2} O produced by combustion reaction of _H 2 O, the combustion flame 24 in the above (2). Moisture contained in the exhaust gas is cooled and condensed by the water passage 74w in the gas passage 74g of the condenser 74 to generate condensed water. The condensed water generated in the gas passage 74 g of the condenser 74 is supplied from the condensed water passage 77 to the water purifier 40 and purified by the water purifier 40. The purified water is stored in the tank 44 as the reformed water 44w. By reusing condensed water as reformed water, the system can be water self-supporting. Water self-supporting means a state where it is not necessary to replenish the system with reforming water over a long period or semipermanently. As described above, the anode off gas is discharged from the upper part of the anode 11 of the fuel cell 1 into the combustion space 23, the cathode off gas discharged from the cathode 12 is discharged into the combustion space 23, and the anode off gas is burned by the cathode off gas. A combustion flame 24 is formed, and the reforming unit 22 and the evaporation unit 20 are heated. In addition, according to the system in which the solid oxide fuel cell 1 is mounted, the operating temperature of the fuel cell 1 in the steady operation is exemplified in the range of 400 to 1100 ° C, and in the range of 500 to 800 ° C.

  A gas temperature sensor 201 for detecting the temperature T2 of the exhaust gas in a portion of the exhaust passage 75 downstream of the gas passage 74g of the condenser 74 is provided. A water temperature sensor 202 that detects the temperature T1 of the water upstream of the water passage 74w of the condenser 74 in the forward passage 71a of the hot water storage passage 71 is provided. An outside air temperature sensor 205 for detecting the outside air temperature T3 is provided in the vicinity of the outside air inlet 92. However, the sensor 205 may be disposed outside the housing 9. Temperature signals from the sensors 201, 202, 205, and 70 t are input to the control unit 100. The control unit 100 includes an input processing circuit, an output processing circuit, a CPU, and a memory. The control unit 100 controls auxiliary machines such as pumps 62, 55, 72, and 42, valves 52 and 43, and a fan 79c.

  The fuel cell 1 is grid-connected to an electric power load 504 and a commercial power source 505 via an inverter 501 and a switching element 502. The power load 504 is connected to the commercial power source 505 via the breaker 506. When the power generation output of the fuel cell 1 is insufficient, power is supplied from the commercial power source 505 to the power load 504 while the switching element 502 is on. When the switching element 502 is disconnected, the fuel cell 1 and the commercial power source 505 are disconnected. Here, if the temperature T1 of the water in the forward passage 71a upstream of the condenser 74 in the hot water storage passage 71 is equal to or higher than the predetermined temperature, the cooling capacity in the condenser 74 is reduced, and the amount of condensation generated in the condenser 74 is reduced. descend. For this reason, when the water level of the reforming water stored in the tank 44 may be excessively lowered, the control unit 100 operates the fan 79c of the radiator device 79 or outputs the output per unit time (the number of rotations) of the fan 79c. ) Is increased, the temperature T1 of the water in the forward passage 71a (the inlet side of the condenser 74) upstream of the condenser 74 in the hot water storage passage 71 is lowered. Thereby, the cooling capacity in the water passage 74w of the condenser 74 increases, and the amount of condensed water condensed in the gas passage 74g of the condenser 74 increases. The condensed water flows down from the condenser 74 to the tank 44 through the condensed water passage 77 by gravity. Thus, the condensed water is supplied to the tank 44 and used as reforming water. According to the present embodiment, when the system is stopped, the hot water storage pump 72 and the cooling fan 79c are stopped. When the system is started, the hot water storage pump 72 and the cooling fan 79c are driven as necessary.

  FIG. 2 shows the tank 44. From the upper part to the lower part of the tank 44, there are three levels of water level: overflow water level Over, high water level High as the first water level, medium water level Mid as the second water level, and low water level Low as the third water level. Is set. High water level sensor 301 (first water level sensor) capable of detecting high water level High, middle water level sensor 302 (second water level sensor) capable of detecting medium water level Mid, low water level sensor 303 (third water level sensor) capable of detecting low water level Low Are respectively provided in the tank 44. Each sensor such as the high water level sensor 301, the middle water level sensor 302, and the low water level sensor 303 may be a conductivity sensor or a float sensor. As for the conductivity sensor, when water is present, the conductivity of water is 2 to 10 μS / cm, but when there is no water, the space between the electrodes becomes air, so that it becomes 0 μS / cm. Presence / absence and presence / absence of impurities can be detected. Of the sensors 301, 302, and 303, the low water level sensor 303 disposed at the bottom is preferably a conductivity sensor. The reason is that water is present at the bottom of the tank 44 even if the amount of water in the tank 44 decreases. For this reason, if impurities are mixed in the tank 44, the probability of detecting the presence / absence of impurities and the presence / absence of pure water increases due to the change in conductivity. An overflow portion 44 p that overflows excess water stored in the tank 44 is provided in the upper portion of the tank 44. Therefore, the overflow water level Over is provided above the high water level High. In the normal power generation mode, the system is set so that the water level of the tank 44 is maintained at a high water level High or higher. Even if water increases in the tank 44, the water overflows from the overflow unit 44p, and the system Drained outside. According to the present embodiment, the system is a water self-supporting type in which power generation operation is performed without supplying water to the tank 44 for a long period of time or semipermanently. For this reason, a supply pipe for supplying supply water such as tap water to the water purifier 40 or the tank 44 is basically not arranged.

  The basic concept of the start permission in this embodiment is shown below. When the amount of condensed water condensed in the condenser 74 decreases, the reformed water recovered in the tank 44 decreases. For example, when the hot water tank 70 is full of hot water (full storage state), the water temperature of the storage passage 71 is high, and the outside air temperature T3 is high (for example, in summer), the hot water tank 70 is condensed in the condenser 74. There is a tendency that the amount of condensed water generated decreases and the reformed water recovered in the tank 44 also decreases. Energy required for system startup and system shutdown so that the benefits of system energy saving, CO2 reduction rate, economy, etc. can be fully demonstrated even under severe conditions for such reformed water storage. In consideration of the above, it is preferable to generate a minimum amount of power for the activated system for the time TM3. Even if the system is started, power generation operation of the system continues for a short time. However, if the system is stopped again in a short time due to the lack of reforming water, sufficient energy saving is not obtained, and the system is running. This is because the cost increases.

An example of studying energy saving is shown below. That is, in the case of a system in which the startup energy of the system is J1 [kWh] and the shutdown energy of the system is J2 [kWh], the energy of J12 is used once in the startup and shutdown of the system. J12 = J1 + J2
On the other hand, when the system generates power with the specified power generation amount and the specified efficiency, it is assumed that there is a reduction in energy of ΔJ3 kW. When the system generates power for time TM3, the energy of ΔJ3 × TM3 [kWh] can be reduced.

  Time TM3 is determined so that the relational expression (ΔJ3 × TM3) ≧ (J12 + α) is satisfied. As for α, it is set as appropriate so as to have an advantage including the cost of the system and the depreciation period. Therefore, when the conditions that allow generation of electric power for time TM3 or longer after the system is started are satisfied, the control unit 100 preferably gives the system start permission and starts the system.

The control unit 100 considers the first condition to the third condition that give the activation permission of the system.
(I) The first condition relating to the water level of the tank 44 (ii) The second condition relating to the amount (water level) of cold water stored in the hot water storage tank 70 not exceeding the first predetermined temperature (iii) The third condition relating to the temperature of the outside air temperature T3 Here, the outside air temperature T3 is used to cool the condenser 74 when the hot water stored in the forward path 71a located upstream of the condenser 74 in the hot water storage passage 71 is cooled by the cooling fan 79c of the radiator device 79. According to the present embodiment, which corresponds to a temperature at which water in the forward path 71c can be actively cooled, the pumps 62, 55, 42, 72, and the fan 79c are stopped before starting. In starting the system, first, the control unit 100 determines whether or not the first condition that the water level of the tank 44 is equal to or higher than a predetermined middle water level Mid is satisfied. Further, it is determined whether or not the second condition that the amount of cold water having a temperature equal to or lower than the first predetermined temperature in the hot water tank 70 is equal to or higher than a predetermined amount is satisfied. Here, warm water exists in the upper part of the hot water tank 70. Due to the difference in specific gravity of water, water having a temperature lower than that of the hot water is substantially separated in the lower part of the hot water tank 70. In the present embodiment, this is called cold water as a term for hot water. The cold water is set to a temperature not higher than a first predetermined temperature (for example, 30 ° C. or 35 ° C.). The amount of cold water corresponds to the water level of cold water. A plurality of temperature sensors 70t are provided in the height direction of the hot water tank 70, and the control unit 100 can recognize the water level of the cold water based on the temperature signal from each temperature sensor 70t. The water level of cold water is assumed to be A1, A2 (A1 <A2) in FIG. The first predetermined temperature is such that water sent from the hot water tank 70 to the water passage 74w of the condenser 74 via the forward passage 71a of the hot water passage 71 (passage portion upstream from the condenser 74) exhibits a condensing action in the condenser 74. It is set to be possible. Furthermore, it is determined whether or not the third condition that the outside air temperature T3 is equal to or lower than a second predetermined temperature (for example, an arbitrary temperature of 20 to 35 ° C.) is satisfied. The second predetermined temperature is set such that the outside air can exhibit a cooling action of cooling the water in the forward path 71a (the passage part upstream from the condenser 74) by the operation of the cooling fan 79c of the radiator device 79.

  And even if it is a water self-supporting type system without supplying water to the system when any of the first condition, the second condition and the third condition is satisfied, even if the system is started Since it is presumed that there is no risk of reforming water shortage, a signal for permitting activation of the system is output by the controller 100. After allowing the system to be activated, the control unit 100 supplies the fuel material to the power generation module 3 and drives the cathode gas pump 62 to supply the cathode gas as combustion air to the power generation module 3. Thereby, the combustion flame 24 is formed, and the evaporation section 20 and the reforming section 22 are heated by the combustion flame 24. The control unit 100 raises the temperature to a temperature range suitable for the reforming reaction by the reforming unit 22, and then drives the pump 42 (reformed water transport source) to supply the reforming water in the tank 44 to the reforming unit 22. Thus, anode gas is generated by the reforming reaction. The anode gas is supplied to the anode 11 of the fuel cell 1 of the power generation module 3. The fuel cell 1 generates power using the anode gas and cathode gas supplied to the power generation module 3. Since the shortage of the reforming water is suppressed, the problem that the system operation is stopped in a short time after activation is prevented in advance. Therefore, energy saving of the system is ensured, and an increase in running cost of the system can be suppressed.

(Embodiment 2)
Since this embodiment basically has the same configuration and the same function and effect as the first embodiment, FIGS. 1 and 2 are applied mutatis mutandis. Also in this embodiment, the system is a water self-supporting type in which power generation operation is performed without supplying water to the tank 44 for a long period or semipermanently. In starting the system, when the first condition that the water stored in the tank 44 is equal to or higher than the middle water level Mid is satisfied, the control unit 100 gives the start permission to the system.

  Further, the control executed by the control unit 100 during the power generation operation of the system will be described below.

  (1) When the system is executing the normal power generation mode according to the load of the power load 504, the amount of condensed water condensed in the condenser 74 is good, and the amount of water in the tank 44 is good. For this reason, the high water level sensor 301 is turned on to detect the high water level. The middle water level sensor 302 is turned on to detect the middle water level. Further, the low water level sensor 303 is turned on to detect the low water level. In this case, the normal power generation mode (power generation based on the power load or the like) of the system is executed. If the generated power of the fuel cell 1 is insufficient and interconnection is necessary, the power of the commercial power supply 505 connected to the grid is supplied to the power load 504.

  (2) In the power generation operation, when the water level of the tank 44 is lowered, the high water level sensor 301 is OFF and does not detect the water level, the intermediate water level sensor 302 is ON and the intermediate water level is detected, and the low water level sensor 303 is detected. ON may detect low water level. In this case, the water level of the tank 44 is located between the high water level High and the middle water level Mid, and the water level of the tank 44 is slightly lowered. Therefore, during the power generation operation, the control unit 100 performs control to limit the output of the maximum power generation output of the fuel cell 1 to the power W1 that is less than the rated power Wset regardless of the request of the power load 504. Examples of the power W1 include an arbitrary value in the range of 95% to 40% of the rated power Wset, particularly 90 to 50%. Thus, when the water level of the tank 44 becomes less than the high water level High, the power generation output of the fuel cell 1 is limited, so that the amount of reforming water consumed in the reformer 2 decreases, and the reformer 2 from the tank 44 decreases. The amount of reforming water supplied per unit time is reduced.

  Further, in the power generation operation, when the water level of the tank 44 becomes less than the high water level High, in some cases, the first operation for turning on the cooling fan 79c or increasing the rotational speed (as compared with the case of the water level higher than the high water level High); Performing at least one of the second operations to increase the output of the pump 72 (as compared to the case where the water level is higher than the high water level High), and lowering the temperature T1 of the water at the inlet of the water passage 74w of the condenser 74; A water increasing operation for increasing the amount of condensed water to be condensed in the condenser 74 can also be executed. In that case, by restricting the power generation output as described above, it is possible to reduce the thermal load of the radiator device 79 and to lower the T1 temperature better, and to improve the increase of condensed water. When the power of the power load 504 is insufficient, the power of the commercial power source 505 connected to the fuel cell 1 is supplied to the power load 504.

  (3) In the power generation operation, the high water level sensor 301 may be OFF and the water level may not be detected, the middle water level sensor 302 may be OFF and the water level may not be detected, and the low water level sensor 303 may be ON and the low water level may be detected. In this case, the water level in the tank 44 is less than the middle water level Mid, and is located between the middle water level Mid and the low water level Low, and the water level in the tank 44 is considerably lowered. In this case, the control unit 100 executes a power generation stop mode for stopping the power generation operation of the system. In this case, it is preferable to stop based on the power generation stop sequence stored in advance in the storage unit of the control unit 100. Further, in some cases, at least one of a first operation for further increasing the rotational speed (output) of the cooling fan 79c and a second operation for further increasing the output of the pump 72 than when the water level is higher than the middle water level High. To increase the generation amount of condensed water condensed in the condenser 74 by lowering the temperature T1 of the water at the inlet of the water passage 74w of the condenser 74. However, the power generation stop mode may be executed without executing the water increasing operation. When the generated power of the fuel cell 1 is insufficient, the commercial power source 505 supplies the power load 504.

  (4) In power generation operation, there are cases where the high water level sensor 301 is OFF and the water level is not detected, the middle water level sensor 302 is OFF and the water level is not detected, and the low water level sensor 303 is OFF and the water level is not detected. In this case, the water level of the tank 44 is located below the low water level Low and is considerably lowered. In this case, the control unit 100 makes an emergency stop of the system. Power from the commercial power source 505 is supplied to the power load 504. In this case, the power generation of the fuel cell 1 is stopped and the supply of the water in the tank 44 to the reformer 2 is stopped. In this case, since the water level in the tank 44 is considerably insufficient, the pump 42 is stopped and the reforming water is not supplied to the reformer 2. As a result, it is possible to suppress deterioration and failure due to coking of the reforming catalyst and the fuel cell catalyst due to insufficient reforming water.

  (5) It is preferable to determine whether ON / OFF of each water level sensor 301, 302, 303 is logically matched. When the logical alignment does not match, the control unit 100 determines that an abnormality such as sticking of the water level sensor has occurred and causes the system to stop urgently. Here, if each water level sensor is ON, the presence of water is detected, and if it is OFF, the absence of water is detected. For example, if the high water level sensor 301 is ON and the high water level is detected, but the intermediate water level sensor 302 is OFF and no medium water level is detected, it is logically impossible. Presumed to be a sensor failure. In addition, if the low water level sensor 303 is OFF and no low water level is detected even though the intermediate water level sensor 302 is ON and the low water level is not detected, it is logically impossible. Presumed.

  As described above, according to the present embodiment, when the sensor 301 detects that the water level of the tank 44 is equal to or higher than the high water level High when the power generation operation is performed, the control unit 100 controls the power load 504. Operate in normal power generation mode according to size. However, when it is detected by the sensors 301 and 302 that the water level of the tank 44 is less than the high water level High and is equal to or higher than the middle water level Mid, the control unit 100 determines whether the fuel cell 1 The maximum power generation output is limited to the generated power W1 less than the rated power Wset, and the rate of decrease in the amount of water in the tank 44 is suppressed. Thereby, the water self-sustained operation of the system can be executed. In the case of water self-sustained operation, the system can be installed even in an environment where there is no makeup water such as tap water. Furthermore, since it is possible to suppress replenishment water such as tap water from being supplied to the system over a long period of time, there is an advantage that deterioration of the water purification material 40a such as an ion exchange resin of the water purifier 40 can be suppressed. Since the system is premised on water self-sustained operation, there is basically no replenishment piping for replenishing water purifier 40 or tank 44 with replenishment water such as tap water. Even if the water level of the tank 44 is lowered, the water self-sustained operation is further facilitated by executing a water increasing operation for increasing the amount of water in the tank 44 while limiting the output to the system.

  As described above, according to the present embodiment, the tank 44 is provided with the three-level water level sensor, that is, the high water level sensor 301, the middle water level sensor 302, and the low water level sensor 303. For this reason, when the hot water tank 70 is filled with warm water and the temperature is high as in the summer, the amount of condensed water condensed in the condenser 74 tends to be insufficient, but external water ( For example, water self-sustained operation is possible without supplying the system with tap water. That is, on most days of the year, excluding hot days, according to the normal power generation mode of the system (when the water is free standing), the water in the tank 44 operates at a water level between the high water level High and the overflow water level over. The amount of water in the tank 44 is sufficient.

  According to the present embodiment, as described above, when the water level of the tank 44 falls below the high water level High and the high water level sensor 301 is turned OFF and no water is detected, the maximum generated power of the system becomes the system rating. Regardless of the power consumption of the power load 504, the control unit 100 limits the power generation operation of the system so that the specified generated power W1 is lower than the power Wset. Due to the output restriction, the amount of reforming water consumed in the reformer 2 is reduced. Further, when the power generation output of the fuel cell 1 decreases, the heat load on the radiator device 79 decreases. As a result, the temperature of the water flowing through the hot water storage passage 71 is lowered, the temperature of the exhaust gas discharged from the power generation chamber 32 of the power generation module 3 toward the exhaust passage 75 can be lowered, and the water balance amount (water balance amount = condensation). It is possible to increase the amount of condensed water produced in the vessel 74 -the amount of reformed water supplied to the reformer 2). According to the above-described embodiment, basically, even when the hot water tank 70 is full of hot water and the outside air temperature is high as in summer, the water level of the tank 44 is less than the high water level High. If there is a medium water level Mid or higher, the system operation can be continued by limiting the output of the generated power of the system. However, there is a possibility that it may occur under unexpected conditions (for example, when the hot time period is longer than expected due to the installation environment, etc., when the hot water storage pump 72 is broken, the specified flow rate is not enough, or the hot water storage passage 71 cannot be flowed). is there. In this case, the water level of the tank 44 is considerably lowered, and there is a possibility that both the high water level sensor 301 and the middle water level sensor 302 are turned off. In this case, when the middle water level sensor 302 is turned off and water cannot be detected, the water in the tank 44 is lower than the middle water level Mid and is lower than the low water level Low, so that the system is shifted to the power generation stop mode. .

  As described above, according to the present embodiment, when starting the system, when the water level of the tank 44 is equal to or higher than the second water level which is the middle water level Mid, it is estimated that there is no fear of the reforming water being insufficient. The control unit 100 outputs a signal for permitting activation of the system. When the water level of the tank 44 is lower than the second water level, which is the middle water level Mid, the control unit 100 does not allow the system to be activated. Further, when the power generation operation of the system is performed, when the water level of the water tank 44 falls below the first water level which is the high water level High, the control unit 100 restricts the maximum power generation output of the system to W1 less than the rated power. . Further, when the water level of the tank 44 is equal to or higher than the first water level which is the high water level High, the water in the tank 44 is sufficient, and the control unit 100 does not limit the maximum power generation output of the system to W1 less than the rated power.

(Embodiment 3)
Since this embodiment basically has the same configuration and the same function and effect as the first and second embodiments, FIGS. 1 and 2 are applied mutatis mutandis. According to the present embodiment, when the system is activated, the control unit 100 determines whether or not the first condition that the water level of the tank 44 is equal to or higher than a predetermined high water level High is satisfied. When the first condition is satisfied, it is presumed that there is no fear of the reforming water, so the control unit 100 allows the system to be started, and then starts the system in the same manner as described above to perform a power generation operation.

(Embodiment 4)
Since this embodiment basically has the same configuration and the same function and effect as the first embodiment, FIGS. 1 and 2 are applied mutatis mutandis. In starting the system, the control unit 100 determines whether or not the water level of the tank 44 satisfies the low water level Low (corresponding to the relaxed first condition in which the first condition is relaxed). Furthermore, it is determined whether or not the second condition that the amount of cold water below the first predetermined temperature in the hot water tank 70 is equal to or greater than a predetermined amount (that is, the cold water is equal to or greater than the water level A2 (A2> A1)). To do. Further, it is determined whether or not the third condition that the outside air temperature T3 is as low as a second predetermined temperature (for example, 20 ° C.) is low. And when relaxation 1st condition, 2nd condition, and 3rd condition are satisfy | filled, since it is estimated that there is no possibility of insufficient reforming water during operation | movement of a system, the control part 100 outputs the signal which permits starting of a system .

(Embodiment 5)
FIG. 3 shows a fifth embodiment. Since this embodiment has basically the same configuration and the same operation and effect as the above-described embodiments, FIGS. 1 and 2 are applied mutatis mutandis. The system is a water self-supporting type in which power generation operation is performed without supplying water to the tank 44 for a long period of time or semipermanently. Before the system is permitted to start, the pumps 42, 55, 62, 72 and the cooling fan 79c are stopped. Also in the present embodiment, when starting the system, if the first condition that the water stored in the tank 44 is equal to or higher than the middle water level Mid is satisfied, it is estimated that there is no risk of insufficient reforming water. Therefore, the control unit 100 gives activation permission to the system. However, if the amount of condensed water generated in the condenser 74 can be expected even if the water stored in the tank 44 is less than the middle water level Mid, the relaxed first condition is set to relax the first condition. When the relaxed first condition is satisfied, the control unit 100 increases the probability of granting the activation permission to the system.

  The flowchart shown in FIG. 3 is executed periodically (eg, every 20 milliseconds) when the system is waiting before starting. First, it is determined whether or not there is a start operation instruction for starting the system and generating power (step S2). The system start-up operation instruction is transmitted to the system by learning control, timer operation, operation of the start switch 102 by the user, and the like. If there is no start operation instruction (NO in step S2), the system standby is continued (step S10). When there is an instruction to start the system (YES in Step S2), the control unit 100 first determines whether or not the first condition that the water level in the tank 44 is equal to or higher than the middle water level Mid (predetermined water level) is satisfied (Step S2). S4). When the water level is equal to or higher than the middle water level Mid and the first condition is satisfied (YES in step S4), it is determined that the operation for the time TM3 or longer is possible. Therefore, the control unit 100 outputs a system activation permission (step S6) and further activates the system (step S8). In this case, the control unit 100 supplies the fuel raw material and the cathode gas into the power generation module 3 to form the combustion flame 24, raises the temperature of the evaporation unit 20 with the combustion flame 24, and makes the reforming unit 22 suitable for the reforming reaction. The temperature is raised to the temperature range. The combustion flame 24 simultaneously raises the temperature of the fuel cell 1. When the temperature of the reforming unit 22 rises, the pump 42 is driven to supply the reforming water in the tank to the reforming unit 22 via the evaporation unit 20. As a result, a reforming reaction occurs in the reforming unit 22 and an anode gas containing hydrogen as an anode active material is generated. The fuel cell 1 generates power using the anode gas and the cathode gas.

  However, even when the water level in the tank 44 is less than the middle water level Mid and the first condition is not satisfied (NO in step S4), the control unit 100 determines that the water level in the tank 44 is equal to or higher than the low water level Low (predetermined water level). It is determined whether or not there is (step S12). If the water level in the tank 44 is lower than the low water level Low (NO in step S12), the control unit 100 issues an alarm 104 and performs a start prohibition process because the water in the tank 44 is very low (step S16). ). In this case, since there is no water replenishment line, the user or the maintenance person replenishes water. Specifically, the panel of the housing 9 is removed, water is supplied to the tank 44 or the water purifier 40 in the storage chamber 91, and the panel is attached after the supply.

  When the water level of the tank 44 is equal to or higher than the low water level Low (YES in step S12), the control unit 100 determines whether or not the cold water in the hot water tank 70 is equal to or higher than the water level A2 (high water level) (step S14). ). Thus, even when the water level of the tank 44 is less than the middle water level Mid and the first condition is not satisfied, when the water level is the low water level Low or higher, the relaxed first condition that relaxes the first condition is satisfied. The In this case, if the water level of the cold water in the hot water tank 70 is A2 or higher (YES in step S14), the second condition is satisfied. In this case, if the pump 72 after the start is driven, the exhaust gas (steam-containing gas) flowing through the gas passage 74g in the condenser 74 is cooled and condensed by the water passage 74w, and a sufficient amount of condensed water is ensured. Is done. That is, since the pump 72 is driven when the system is started, it is determined that the condensed water generation capability in the condenser 74 is ensured. Therefore, the control unit 100 determines that power generation is possible for the time TM3 or more, outputs a system activation permission (step S6), and further activates the system (step S8).

  By the way, when the outside air temperature T3 is high, the cooling fan 79c of the radiator device 79 cannot sufficiently cool the water in the forward path 71a. In this case, the reforming water in the tank 44 may be insufficient. Even in such a harsh environment, if the cold water at the bottom of the hot water tank 70 is above the water level A2 and the amount of cold water in the hot water tank 70 is secured, the system is activated and the pump 72 is driven, The condensate generation capability of the condenser 74 can be secured, and even if the system is activated, it can be operated for a time TM or more. From such a viewpoint, the height of the water level A2 of the cold water in the hot water tank 70 is set. As an example, the amount of hot water used for system startup is Q1 [liter], and the amount of hot water used for power generation is Q2 [liter] (= q2 [liter / min] × TM3). In this case, the height of the cold water level A2 in the hot water storage tank 70 is set so as to ensure a water amount of Q1 + Q2 or more.

  Further, when the cold water at the bottom of the hot water tank 70 is less than the water level A2 (NO in step S14), the cold water is small, and there is a possibility that the amount of condensed water generated in the condenser 74 cannot be expected so much. Therefore, the control unit 100 determines whether or not the outside air temperature T3 is lower than the threshold value T3-a (step S20). If the outside air temperature T3 is higher than the threshold value T3-a (T3> T3-a) (NO in step S20), the third condition is not satisfied and the cooling capacity of the radiator device 79 is reduced. There is a possibility that the water cannot be sufficiently cooled and the amount of condensed water generated in the condenser 74 is not necessarily sufficient. Therefore, when the cold water in the hot water storage tank 70 is less than the water level A2, it is determined that power generation for the time TM3 or more is difficult, and thus the activation permission is suppressed. Here, the threshold value T3-a is basically a temperature (corresponding to the second predetermined temperature) determined based on the cooling capacity of the radiator device 79. In consideration of daily temperature changes and the like, the temperature at which the tank 44 is drained and the system does not stop within the time TM3 is set as the threshold T3-a. Note that the threshold T3-a may be set as a map with respect to time. For example, when the system start-up operation instruction is output at 6:00 AM, T3−a = 30 ° C. can be set. When the time when the system startup operation instruction is output is 12:00, T3-a = 35 ° C. is exemplified. As described above, even if the water level of the tank 44 is lower than the middle water level Mid (when the first condition is not satisfied), if the water level is not lower than the low water level Low (YES in step S12), the relaxed first condition is satisfied. Is done. In this case, when the user consumes the hot water in the hot water tank 70, the height of the cold water level at the bottom of the hot water tank 70 increases to the water level A2 or higher, and the second condition is satisfied (YES in step S14). Therefore, the process proceeds from step S14 to step S6, where the control unit 100 outputs a system activation permission (step S6) and activates the system (step S8).

  Even if the water level in the tank 44 is less than the middle water level Mid, if the water level is equal to or higher than the low water level (YES in step S12), the relaxed first condition is satisfied. In this case, even if the cold water in the hot water tank 70 is lower than the water level A2 (when the second condition is not satisfied) (NO in step S14), the third condition is because the outside air temperature T3 is as low as the threshold value T3-a or lower. Is satisfied (T3 ≦ T3-a). In this case, when the water level of the cold water in the hot water tank 70 is equal to or higher than A1 (A1 <A2) (when the relaxed second condition that relaxes the second condition is satisfied) (YES in step S22), the radiator is activated by activation. If the fan 79c of the device 79 is driven, the water in the forward passage 71a of the hot water storage passage 71 can be effectively cooled, the amount of condensed water generated in the condenser 74 can be secured, and the water in the tank 44 can be increased. That is, when the system is activated, it is determined that the condensed water generation capability in the condenser 74 is ensured. Therefore, it is determined that power generation can be performed for time TM3 or more, and the control unit 100 outputs a system activation permission (step S6) and activates the system (step S8). When the system is activated, the pump 72 and the fan 79c are driven, so that the condensed water generation capability of the condenser 74 is increased.

  Furthermore, even if the water level in the tank 44 is lower than the middle water level Mid, if the water level is lower than the low water level Low (YES in step S12, the first relaxation condition is satisfied), the cold water in the hot water tank 70 is lower than the water level A1. If the outside air temperature T3 is lower than the threshold value T3-b (for example, 10 ° C.) (T3 ≦ T3-b, If the pump 72 and the fan 79c of the radiator device 79 are driven by the start-up, the cooling capacity of the radiator device 79 is ensured and cooling of the water in the forward path 71a of the hot water storage passage 71 can be expected. As a result, the amount of condensed water condensed in the condenser 74 can be increased, and the water level of the tank 44 rises. That is, when the system is activated, it is determined that the condensed water generation capability in the condenser 74 is ensured. In this case, it is determined that power generation for time TM3 or more is possible. Accordingly, the control unit 100 proceeds from step S24 to step S6, outputs a system activation permission, and activates the system (step S8). Here, T3-b is at a lower temperature than T3-a.

  Regarding the height of the cold water level A1 in the hot water storage tank 70, when the outside air temperature T3 is equal to or lower than a threshold T3-a (for example, 20 ° C.) (T3 ≦ T3-a), power generation can be continued for more than time TM3. The amount of water is set. Here, when there is no cold water in the hot water tank 70 (that is, when the hot water tank 70 is full of hot water), the water cooling effect by the radiator device 79 is reduced, and the condensed water generating ability in the condenser 74 is reduced. Withering may occur. For this reason, the height of the water level A1 of the cold water in the hot water tank 70 is set so that the sum of the time during which the system can be operated without running out of water is equal to or greater than the time TM3.

  When the cold water in the hot water storage tank 70 is less than the water level A1 (NO in step S22, when the relaxed second condition that relaxes the second condition is not satisfied), and the outside air temperature T3 is higher than the threshold temperature T3-b (NO in step S24), there is a possibility that the condensed water generation capability in the condenser 74 may not be ensured satisfactorily. Therefore, even if the system is activated, the control unit 100 returns from step S24 to step S2 because there is a high possibility that the system will immediately stop. Here, even if the hot water storage tank 70 continues to be full with hot water, that is, when there is no cold water in the hot water storage tank 70, the threshold value T3-b This is a possible temperature. The concept of the threshold value T3-b is the same as that of the threshold value T3-a.

  Even when the amount of cold water in the hot water storage tank 70 is as low as less than the water level A1 (NO in step S22, when the relaxed second condition is not satisfied), when the outside air temperature T3 is as low as the threshold value T3-b (in step S24) YES, T3 ≦ T3-b), the water in the forward passage 71a of the hot water storage passage 71 is effectively cooled by driving the fan 79c of the radiator device 79, and the amount of condensed water condensed in the condenser 74 is increased. The risk of water drainage is eliminated. That is, when the system is activated, it is determined that the condensed water generation capability in the condenser 74 is ensured. Therefore, the control unit 100 outputs a system activation permission (step S6) and activates the system (step S8). When the system is started, the pump 72 and the fan 79c are driven, so that the condensed water generation capability of the condenser 74 is increased, and the tank 44 is increased in water. As described above, even if the user does not use the hot water in the hot water tank 70 and the hot water in the hot water tank 70 is full, the outside air temperature T3 is equal to the temperature T3-a, When the temperature is lower than T3-b, if the fan 79c rotates, the cooling capacity of the radiator device 79 is secured, and the condensed water generation capacity in the condenser 74 is secured, so the control unit 100 activates the system. be able to. Thus, according to this embodiment, water independence can be performed without supplying water to the system. Furthermore, it is possible to improve the total efficiency, energy saving, economy and the like throughout the year in the system.

FIG. 4 schematically shows a concept of a characteristic example when the control shown in FIG. 3 is performed. A characteristic line M1 indicates a change in the water level of the tank 44. A characteristic line M2 indicates a user's power generation request. A characteristic line M3 indicates a change in the power generation output of the fuel cell 1. A characteristic line M4 indicates a change in the water level of the cold water in the hot water tank 70. indication of start-up allowed in t ₀ is assumed to come. In that case, the reforming water tank is not higher than Mid (Step 4 NO), but since it is Low or higher (Step 12 YES) and the hot water tank cold water level A2 or higher (Step 14 YES), the control unit 100 satisfies the relaxation condition 1. to start the start given the start-up permitted in t _0. Thereafter, power generation of the fuel cell 1 is started at time tu when the warming-up of the reforming unit and the fuel cell is completed. However, at time tu, since the water in the tank 44 is less than the high water level High, the power generation output is limited. Therefore, after the time tu, the maximum power generation output of the fuel cell 1 is suppressed to W1 lower than W2, although the user's power generation request is the output W2. After the time tw when the water in the tank 44 becomes higher than the high water level High, the above restriction is released. For this reason, the power generation output of the fuel cell 1 becomes substantially the same as the user's power generation request, and is increased to W2 higher than W1. As the power generation time elapses, the flow rate at which the hot water heated by heat exchange in the condenser 74 returns to the hot water tank 70 increases, so that the cold water level in the hot water tank 70 gradually decreases as shown by the characteristic line M4. However, as shown by the characteristic line M1, the water level of the tank rises due to an increase in the amount of condensation in the condenser by cold water, and the user does not use hot water at all, and the cold water level of the tank becomes zero (the hot water fills up). Power generation over a predetermined time TM3 is possible.

(Embodiment 6)
FIG. 5 shows a sixth embodiment. Since this embodiment basically has the same configuration and the same operation and effect as the above-described embodiments, FIGS. 1 and 2 are applied mutatis mutandis. The system is a water self-supporting type. The flowchart shown in FIG. 5 is executed periodically when the system is waiting. First, it is determined whether or not there is a start operation instruction for starting the system and generating power (step SB2). The system start-up operation instruction is transmitted to the system by learning control, timer operation, operation of the start switch 102 by the user, and the like. If there is no startup operation instruction (NO in step SB2), the standby of the system is continued (step SB10). When there is a system startup operation instruction (YES in step SB2), the control unit 100 first determines whether or not the water level in the tank 44 is equal to or higher than the middle water level Mid (step SB4). When the water level is equal to or higher than the mid-water level (YES in step SB4), the first condition is satisfied, the amount of water in the tank 44 is sufficient, and it is estimated that there is no risk of reforming water. Is determined to be possible. For this reason, the control unit 100 outputs a system activation permission (step SB6) and further activates the system (step SB8). As a result, a reforming reaction occurs in the reforming unit 22 and an anode gas containing hydrogen as an anode active material is generated.

  When the water level in the tank 44 is less than the middle water level Mid (NO in step SB4), the first condition is not satisfied. Therefore, the control unit 100 determines whether or not the water level of the tank 44 is equal to or higher than the low water level Low (step SB12). When the water level in the tank 44 is lower than the low water level Low (NO in step SB12), even the first relaxation condition is not satisfied and the control unit 100 outputs a system activation permission because the water in the tank 44 is low. Instead, the alarm 104 is issued and the activation prohibition process is performed (step SB16). When the water level in the tank 44 is less than the mid-water level Mid and equal to or higher than the low water level Low (YES in step SB12), the relaxed first condition is satisfied. Then, the control part 100 determines whether the cold water of the hot water tank 70 is more than the water level A2 (high water level) (step SB14). When the cold water in the hot water tank 70 is equal to or higher than the water level A2 (high water level) (YES in step SB14), the second condition is satisfied. Therefore, even when the water level in the tank 44 is low, the pump 72 can be driven to supply a large amount of cold water in the hot water tank 70 to the forward path 71a of the hot water storage passage 71 regardless of the outside air temperature T3. In this case, the amount of condensed water condensed in the gas passage 74g is secured by the water passage 74w of the hot water storage passage 71 in the condenser 74. That is, when the system is activated, it is determined that the condensed water generation capability in the condenser 74 is ensured. For this reason, although the water level of the tank 44 is less than the middle water level Mid and the low water level is Low or higher, that is, the control unit 100 can generate power for the time TM3 or more even though the water amount of the tank 44 is small. Judgment is made, the system activation permission is output (step SB6), and the system is further activated (step SB8). When the cold water in the hot water storage tank 70 is less than the water level A2 (high water level) (NO in step SB14), the first condition is satisfied but the second condition is not satisfied. Without returning to step SB2.

(Embodiment 7)
FIG. 6 shows a seventh embodiment. Since this embodiment has basically the same configuration and the same operation and effect as the above-described embodiments, FIGS. 1 and 2 are applied mutatis mutandis. Also in this embodiment, the system is a water self-supporting type. In starting the system, when the first condition that the water stored in the tank 44 is equal to or higher than the middle water level Mid is satisfied, the control unit 100 gives the start permission to the system. However, even if the water stored in the tank 44 is less than the middle water level Mid and the first condition is not satisfied, the control unit 100 gives the system permission to start if the third condition is satisfied.

  The flowchart shown in FIG. 6 is executed periodically when the system is waiting. First, it is determined whether or not there is a start operation instruction for starting the system and generating power (step SC2). The system start-up operation instruction is transmitted to the system by learning control, timer operation, operation of the start switch 102 by the user, and the like. If there is no start-up operation instruction (NO in step SC2), the system standby is continued (step SC10). When there is an instruction to start the system (YES in step SC2), the control unit 100 first determines whether or not the water level in the tank 44 is equal to or higher than the middle water level Mid (step SC4). When the water level is equal to or higher than the mid-water level Mid (YES in step SC4), it is determined that the first condition is satisfied, the amount of water in the tank 44 is sufficient, and the operation can be performed for the time TM3 or longer. Therefore, the control unit 100 outputs a system activation permission (step SC6), and further activates the system (step SC8). When the water level in the tank 44 is less than the middle water level Mid (NO in step SC4), the first condition is not satisfied. Therefore, the control unit 100 determines whether or not the water level in the tank 44 is equal to or higher than the low water level Low (step SC12). If the water level in the tank 44 is lower than the low water level Low (NO in step SC12), even the first relaxation condition is not satisfied and the control unit 100 outputs a system activation permission because the water in the tank 44 is low. Instead, the alarm 104 is issued and the activation prohibition process is performed (step SC16). When the water level in the tank 44 is lower than the middle water level Mid and is equal to or higher than the low water level Low (YES in step SC12), the first relaxation condition is satisfied. Therefore, control unit 100 determines whether or not outside air temperature T3 is equal to or lower than threshold value T3-a (step SC14). When the outside air temperature T3 is as low as the threshold value T3-a or lower (YES in step SC14), the third condition is satisfied, so that even when the water level in the tank 44 is low, the radiator device 79 causes the water in the forward path 71a to flow. Can be effectively cooled, the amount of condensed water condensed in the condenser 74 can be secured, and the water level of the tank 44 can be increased. That is, when the system is activated, it is determined that the condensed water generation capability in the condenser 74 is ensured. For this reason, if the water level of the tank 44 is not less than the low water level Low, the control unit 100 generates power for the time TM3 or more even though the water level in the tank 44 is low, that is, it is low. It judges that it is possible, outputs a system activation permission (step SC6), and further activates the system (step SC8). When the outside air temperature T3 is higher than the threshold value T3-a (NO in step SC14), the control unit 100 returns to step SC2 without outputting the system activation permission. The threshold value in step SC14 may be the threshold value T3-b instead of the threshold value T3-a.

(Embodiment 8)
Since this embodiment basically has the same configuration and the same function and effect as the above-described embodiments, FIGS. 1 to 6 are applied mutatis mutandis. The system is a water self-supporting type. The cooling fan 79c of the radiator device 79 is ON / OFF controlled based on the temperature T1 of the water in the forward path 71a of the hot water storage passage 71 or the exhaust gas temperature T2 of the exhaust path 75, thereby cooling the water in the forward path 71a of the hot water storage passage 71. For example, the cooling fan 79c is turned on when T1 ≧ 38 ° C., and the cooling fan 79c is turned off when T1 ≦ 40 ° C. Alternatively, the cooling fan 79c is turned ON when the exhaust gas temperature T2 ≧ 43 ° C., and the cooling fan 79c is turned OFF when the exhaust gas temperature T2 ≦ 45 ° C.

  The amount of condensed water condensed in the condenser 74 is determined by the exhaust gas temperature T2 based on the saturated water vapor curve of the exhaust gas. The temperature T2 of the exhaust gas is determined based on the temperature T1 of the water in the forward path 71a of the hot water storage passage 71. Therefore, the amount of condensed water condensed in the condenser 74 can be controlled by the temperature T1 of the water in the hot water storage passage 71 and the temperature T2 of the exhaust gas. In consideration of responsiveness, it is preferable to control the temperature by the water temperature T1 of the hot water storage passage 71 in which the cooling capacity of the radiator device 79 appears early. Control based on the water level sensor of the tank 44 will be described below. Normally, the system is operated so that the water level of the tank 44 is between the high water level High and the overflow water level over. When the hot water tank 70 is hot and not full, low temperature water exists near the bottom of the hot water tank 70. This low-temperature water is supplied to the water passage 74 w of the condenser 74. If the temperature T2 of the exhaust gas in the exhaust passage 75 can be cooled to 42 to 45 ° C. or less in the gas passage 74g of the condenser 74, the amount of condensed water condensed in the condenser 74 increases, and as a result, reforming that is stored in the tank 44. The amount of water increases. For this reason, the balance of the reformed water in the system becomes positive, and it is not necessary to supply the system with the supplementary water such as tap water as the reformed water over a long period of time. Here, assuming that the temperature difference between the exhaust gas in the gas passage 74g and the water in the water passage 74w in the condenser 74 is 2 ° C., the radiator so that the water in the hot water storage passage 71 is in a temperature range of 40 to 43 ° C. or less. If the inlet temperature of the water passage 74w of the condenser 74 in the hot water storage passage 71 can be cooled by the device 79, the system can be independent of water. When the water level of the tank 44 exists between the high water level High and the overflow water level over, the amount of water stored in the tank 44 is sufficient even if the rated operation of the system continues. For this reason, the control unit 100 can control the power generated by the fuel cell 1 based on the amount of power consumed by the power load 504. The rating here means the limit of use guaranteed by the manufacturer even under the conditions specified for the system.

  On the other hand, when the hot water storage tank 70 is full of hot water and the outside air temperature is high (for example, a hot summer day in summer or the tropical region), the forward path 71a of the hot water storage passage 71 (the inlet side of the condenser 74). ) Becomes high, the cooling capacity in the condenser 74 is insufficient, and as a result, the amount of condensed water condensed in the condenser 74 may be insufficient. Thus, when the outside air temperature is high, even if the water in the forward path 71a of the hot water storage passage 71 is cooled by the radiator device 79, the temperature T1 of the water is in a temperature range exceeding 40 to 43 ° C. on the high temperature side. For this reason, if the rated power generation operation is continued, the cooling capacity in the condenser 74 becomes insufficient, and the amount of condensed water generated in the condenser 74 becomes insufficient. In this case, the water level of the tank 44 may be lowered. Therefore, when the control unit 100 detects that the high water level sensor 301 is OFF (no water), the control unit 100 determines whether the power load consumed by the power load 504 is the highest level of the system. The output is limited so that the generated power becomes W1 (less than the rated power Wset). In general, when the generated power is lower, the amount of reformed fuel is reduced, and hence the amount of reformed water can be reduced, the decrease in the water level of the tank 44 can be suppressed, and the heat load of the cooling device can be reduced to reduce the T1 temperature. Condensed water can be increased by lowering and thus improving the condensing capacity of the condenser 74. As a result, it is possible to suppress a reduction in the amount of reforming water stored in the tank 44.

  By the way, the tank capacity of water stored in the tank 44 below the overflow water level over the high water level High is assumed to be H1 (see FIG. 2). The tank capacity of water stored in the tank 44 below the high water level High and above the middle water level Mid is defined as H2 (see FIG. 2).

  The determination of the tank capacities H1 and H2 will be described below. A characteristic line WA in FIG. 7 shows a temperature change actually measured on a specific reference day in a summer in a certain year. This reference date indicates a hot day that shows the annual maximum temperature in a given country (Japan) where the system is installed so that it is almost the worst condition for one year for the generation of condensed water. As shown by the characteristic line WA in FIG. 7, the outside air temperature rises from 7 o'clock (7 am) to 15:00 (3 pm) during the daytime. From 2 am (2 am) to 7 am (7 am), the outside air temperature is relatively low. From 20:00 (8 pm) to 24:00 (midnight), the outside air temperature is relatively low. When the outside air temperature is high, the condensation in the condenser 74 is restricted, the amount of condensed water produced in the condenser 74 is reduced, and the water level of the tank 44 tends to be lowered. For this reason, in determining the tank capacities H1 and H2 of the tank 44, a reference is made on a very hot day showing the annual maximum temperature where the amount of condensed water generated is drastically reduced. Therefore, the extremely hot day is set as the reference date.

  FIG. 8 shows a simulation result of the water balance of the tank 44 in a state where the generator device W continues to be operated all day with the generated power W1 of the fuel cell 1 while cooling the water in the hot water storage passage 71 by the radiator device 79. Show. In this case, the water balance for a specified time (per minute) when the exhaust gas can be cooled to + 4 ° C. with respect to the outside air temperature by the ability of the radiator device 79 and the ability of the condenser 74 is shown. The horizontal axis of FIG. 8 indicates time, and the vertical axis indicates the water balance (relative display) of the tank 44. Here, since the outside air temperature rises in the daytime, the amount of generated water condensed in the condenser 74 decreases as shown by the characteristic line WB in FIG. 8, from 9:00 (9:00 am) to 19:00 ( 7pm), the water balance becomes negative due to the influence of outside air temperature. However, since the outside air temperature decreases at night, the amount of condensed water condensed in the condenser 74 increases, and the water balance becomes positive as shown by the characteristic line WB in FIGS. .

  The characteristic line WC in FIG. 9 and FIG. 10 shows the simulation result of the water balance in the tank 44 per day on the reference day. In this case, the fuel cell 1 continuously generates power, and the power generation output is W1. The horizontal axis in FIG. 9 indicates time, and the vertical axis indicates the water balance (relative display) of the tank 44. When looking at the accumulation at each time, a predetermined reference time on the reference day (24 hours = midnight in FIGS. 9 and 10) is set so that the water balance becomes zero in one-day operation. The amount of water stored in the tank 44 at the time (24:00) is displayed as a relative 0 value.

  According to the characteristic line WC of FIGS. 9 and 10, the amount of water stored in the tank 44 is alternately curved (for example, a sine curve) on the plus side and the minus side according to the change in the temperature on the day of the reference day. It changes in shape. That is, according to the characteristic line WC, water continues to increase while maintaining a water balance plus from 1 o'clock to 8 o'clock. Furthermore, from 9 o'clock to 14 o'clock, the water balance continues to decrease while the water balance plus remains positive. From 14:00 to 18:00, water continues to decrease while maintaining a negative water balance. From 19:00 to 24:00, water continues to increase while maintaining a negative water balance. Here, with respect to the amount of reformed water stored in the tank 44 that changes in accordance with the air temperature on the reference day (extremely hot day), the maximum peak value relative to the 0 value is Vmax. Further, the minimum peak value with respect to the relative 0 value of the reformed water storage amount is set to Vmin.

  According to the present embodiment, if the tank capacity of the tank 44 that can store the reformed water at the high water level High or higher and below the overflow water level over is H1, the tank capacity H1 reduces the amount of condensed water generated. Therefore, it is set based on the maximum peak value Vmax on a very hot day when the tank 44 tends to dry out. Specifically, the tank capacity H1 is set based on the total sum of the maximum peak value Vmax and the first margin capacity Vα. The first margin capacity Vα means the amount of surplus water in the tank 44 in consideration of the safety factor, and is appropriately set according to the type of system, the installation environment of the system, and the like. If the amounts of Vmax and Vα are the same unit, Vmax> Vα can be established.

  Further, assuming that the tank capacity of the tank 44 that can store the reformed water below the high water level High and above the middle water level Mmid is H2, the tank capacity H2 is extremely hot where the amount of condensed water generated tends to decrease. It is set based on the minimum peak value Vmin in the day. Specifically, the tank capacity H2 is set based on the total sum of the minimum peak value Vmin and the second margin capacity Vβ. The second margin capacity Vβ means a surplus water amount in the tank 44 in consideration of the safety factor, and is appropriately set according to the system, the installation environment of the system, and the like. If the amounts of Vmin and Vβ are the same unit, Vmin> Vβ can be satisfied. Note that Vα = Vβ, Vα> Vβ, and Vα <Vβ. If Vα> Vβ, there is an advantage that the amount of water higher than the high water level High can be increased, and the output restriction can be suppressed. Vα = Vβ≈0 may be used.

  According to the present embodiment as described above, the system can be independent of water while suppressing an increase in the capacity of the tank 44, and it is not necessary to replenish the system with reforming water such as tap water over a long period of time. I understand that. That is, according to the characteristic line WC in FIG. 10, surplus condensed water can be stored in the tank 44 from 0:00 to 14:00 (2 pm). On the other hand, from 14:00 (2pm) to 24:00 (midnight), the water level of the tank 44 decreases. However, the capacity of the deficient water corresponding to approximately 10 hours from 14:00 to 24:00 The capacity H2 can be secured in the tank 44. Accordingly, it is possible to continuously operate the fuel cell 1 without stopping the power generation while the amount of stored water in the tank 1 is reduced. According to the present embodiment, the tank capacity H1 and the tank capacity H2 of the tank 44 are determined based on the above viewpoint. As described above, the tank capacities H1 and H2 of the tank 44 are determined. For this reason, the tank 44 does not run out of water even on a very hot day when the amount of condensed water produced decreases.

  However, when the condenser 74 is not cooled due to an unexpected environmental condition, a malfunction of the hot water storage pump 72, or the like, the water level of the tank 44 may further decrease due to various factors such as abnormality. Therefore, when the middle water level sensor 302 is detected to be OFF (no water), the control unit 100 shifts the system from the power generation mode to the power generation stop mode. The power generation stop mode is power generation stop means when the system stops normally.

  The power generation stop mode will be described in the following I to III.

  I. In response to the power generation stop instruction, the control unit 100 reduces the outputs of the pumps 55 and 42 so that the fuel raw material and the reformed water supplied to the reformer 2 have a minimum flow rate. Furthermore, the control unit 100 increases the output of the cathode gas pump 62 to increase the cathode gas. Thereby, the inside of the power generation module 3 is cooled while continuing combustion of the combustion flame 24 in the combustion space 23. In this case, until the temperature of the reformer 2 or the fuel cell 1 becomes equal to or lower than the predetermined temperature Tc, the fuel raw material and the reforming water are supplied to the reformer 2 in order to keep the anode system such as the anode of the fuel cell 1 in a reducing atmosphere. The power generation module 3 is cooled while being supplied and generating a hydrogen-containing gas having reducibility.

  II. When the temperature of the reformer 2 or the fuel cell 1 falls below the predetermined temperature Tc, the pumps 55 and 42 are stopped, and the operation of supplying the fuel material and reforming water to the reformer 2 is shut off. In this case, hydrogen remaining in the power generation chamber 32 of the power generation module 3 is discharged to the exhaust passage 75 with the cathode gas and purged.

  III. When the temperature of the reformer 2 or the fuel cell 1 is cooled below a predetermined temperature Te lower than II, the system is completely stopped, and the system auxiliary devices (for example, valves and pumps) are also completely stopped.

  Now, the tank capacity of the tank 44 that is less than the middle water level Mid and equal to or higher than the low water level Low is set to H3. A method for setting the tank capacity H3 will be described. That is, FIG. 1011 shows an example of the water balance of the tank 44 in the power generation stop mode of the system. In the power generation stop mode, as described above, the amount of combustion of the fuel material supplied to the reformer 2 and the amount of reforming water are small, but the power is supplied into the power generation module 3 to cool the inside of the power generation module 3. The amount of cathode gas increases. For this reason, since the water vapor fraction contained in the exhaust gas flowing through the exhaust passage 75 becomes low, the amount of condensed water condensed in the condenser 74 is insufficient unless the temperature of the exhaust gas is cooled to 10 ° C. or lower. become. However, in practice, since it is difficult to cool the exhaust gas temperature to 10 ° C. or less, in the power generation stop mode, there is a possibility that the shortage of reforming water is V shortage in the worst case. Therefore, for the tank capacity H3 of the tank 44 that is less than the middle water level Mid and lower than the low water level Low, a shortage value Vshortage that is insufficient in the power generation stop mode and a water amount Vstart that is necessary for the next start-up are secured. It is preferable. Here, FIG. 12 shows the water balance in the start-up mode. However, since the water balance characteristic is almost the same as that in the power generation operation, the water amount Vstart is substantially about 50 to 100 cc regardless of the characteristic of FIG. I think it would be nice. When the middle water level Mid of the tank 44 is detected, the system shifts from the power generation mode to the power generation stop mode. Similarly, when the water level in the tank 44 further decreases due to unexpected factors, and the water level becomes lower than the low water level Low, the control unit 100 performs an emergency stop. Here, the emergency stop is a stop method on the premise that supply of reforming water to the reformer 2 is stopped, and the reforming catalyst and the fuel cell accommodated in the reformer 2 are not deteriorated. As such, the supply of the fuel material and the like to the reformer is also stopped. Parts that are not directly related to power generation, such as hot water and ventilation air, may be operated, or all auxiliary equipment may be stopped. This prevents the reforming catalyst 2 and the fuel cell 1 from deteriorating due to insufficient reforming water supplied to the reformer 2 when the reforming water in the tank 44 is completely exhausted. And deterioration of the fuel cell 1 is suppressed. In this case, the control unit 100 determines that there is an abnormality, performs maintenance of inspection of the hot water storage pump 72 and the like, and replenishes reforming water.

  As described above, also in this embodiment, when the sensors 301 and 302 detect that the water level of the tank 44 is equal to or higher than the high water level High, the control unit 100 causes the power load 504 to be detected. The power generation output of the fuel cell 1 is controlled in accordance with the magnitude of. When the sensor detects that the water level in the tank 44 is less than the high water level High, the control unit 100 limits the power generation output of the fuel cell 1 to less than the rated power regardless of the size of the power load 504. By doing so, the reduction | decrease of the reforming water of the tank 44 is suppressed. Thereby, the water self-sustained operation of the system can be executed. That is, a series of controls and the configuration of the tank 44 enable water-independent power generation operation without supplying new water as reformed water to the system. When an abnormality occurs when the water level of the reforming water in the tank 44 is excessively lowered, the system can be stopped before the reformer 2 and the fuel cell 1 are deteriorated. Pure water has high electrical insulation. If the quality of the reformed water deteriorates, the electrical conductivity of the water increases. For this reason, when a conductivity meter is used as the low water level sensor 303, the water quality of the tank 44 deteriorates due to deterioration of the ion exchange resin of the water purifier 40, deterioration of the water purification capacity, deterioration of the fuel cell, etc. It is possible to detect that the conductivity is increased (that is, the conductivity of water is abnormal). In particular, the low water level sensor 303 is arranged at the lowest position among the water level sensors provided in the tank 44. For this reason, the effect that the quality of the water stored in the tank 44 can be detected irrespective of the fluctuation of the water level of the tank 44 is obtained.

(Other embodiments)
(1) The activation is permitted even when only the second condition is satisfied.
Even if the amount of water in the tank 44 does not satisfy the relaxed first condition, or even if there is almost no amount of water in the tank 44, the combustion exhaust gas that is supplied with the fuel material and cathode gas and burned in the combustion space is condensed into the condenser 74. Thus, condensed water is collected in the tank 44, and when the amount of water in the tank 44 can be secured to some extent, it can be started by starting the supply of reforming water. However, it is preferable to permit activation when the first relaxation condition is satisfied because coking in the reformer 2 can be reduced.

(2) Permits activation even when only the third condition is satisfied.
The explanation is the same as above.

  (3) Activation is permitted based on the amount of water in the reforming water tank 4 and the amount of water below the first predetermined temperature in the hot water storage tank 70. Rather than determining the start permission based on the predetermined water level and the predetermined amount, the amount of water in the reforming water tank 44 and the amount of water below the first predetermined temperature in the hot water tank 70 are used to start the reforming water after the system is started. The balance of water amount is calculated, and activation is permitted when a condition that enables power generation for time TM3 or more is satisfied. In this case, the cold water temperature of the hot water may be added to the calculation factor. Moreover, when starting by learning control, it is preferable to calculate in consideration of an operation plan. Considering the performance factor of the apparatus in advance, the activation permission determination is made using a map in which the relationship between the amount of water in the reforming water tank 44 and the amount of water below the first predetermined temperature in the hot water tank 70 and the activation permission is determined. You may do it. Note that the amount of cold water in the hot water storage tank 70 can be calculated by using the values of the plurality of temperature sensors 70t even if they are in the middle of the temperature sensor 70t. The amount of water in the reforming water tank 44 can be calculated from, for example, the pressure detected by a pressure sensor provided at the bottom of the tank 44.

  (4) The control unit 100 permits activation based on the amount of water in the reforming water tank 44, the amount of water below the first predetermined temperature in the hot water storage tank 70, and the temperature of the outside air. In this case, instead of making a start permission determination based on the determined predetermined water level, predetermined amount, and predetermined temperature, the control unit 100 determines the amount of water in the reforming water tank 44, the amount of water below the first predetermined temperature in the hot water tank 70, The balance of the amount of reforming water after the system is started is calculated using the temperature of the outside air, and the start-up is permitted when a condition capable of generating power for the time TM3 or more is satisfied. In this case, the cold water temperature of the hot water may be added to the calculation factor. When starting by learning control, it calculates in consideration of an operation plan. In consideration of the performance factors of the apparatus, a map in which the amount of water in the reforming water tank 44, the amount of water below the first predetermined temperature in the hot water tank 70, the relationship between the outside air temperature and the start permission is used. The activation permission may be determined.

(Application form)
FIG. 13 shows an example of the application form. Since the present embodiment shows the same configuration and effect as the above-described embodiment, other drawings can be applied mutatis mutandis. As shown in FIG. 13, the plurality of fuel cells 1 are arranged side by side through a passage 32r to which a cathode gas is supplied to form a stack. The fuel cells 1 are electrically connected by a current collector (not shown). The fuel cell 1 includes a porous conductive portion 11w having a passage 11r through which an anode gas flows, an anode 11 that functions as a fuel electrode, a cathode 12 that functions as an oxidant electrode facing the passage 32r to which a cathode gas is supplied, It has an electrolyte membrane 15 using a solid oxide sandwiched between an anode 11 and a cathode 12 as a base material, and a dense connector 10x. The solid oxide has a property of conducting oxygen ions (O ²⁻ ), and examples thereof include zirconia type such as YSZ and lanthanum gallate type. The anode 11 is exemplified by nickel-ceria cermet. Examples of the cathode 12 include samarium cobaltite and lanthanum manganite. The material is not limited to the above. An anode gas manifold 13 that guides the anode gas to the inlet of the fuel cell 1 is disposed below the fuel cell 1.

(Other)
According to the above-described embodiment, the tank 44 is provided with the high water level sensor 301, the middle water level sensor 302, and the low water level sensor 303. However, a single sensor detects the high water level, the middle water level, and the low water level. Anyway. Although the high water level sensor 301, the middle water level sensor 302, and the low water level sensor 303 are provided, only the high water level sensor 301 and the middle water level sensor 302 may be used. In short, it is only necessary to detect a plurality of levels of water in the tank 44. Condensed water generated by the condenser 74 is stored in the tank 44 after being stored in the water purifier 40 having a water purification function and purified, but the condensate water generated by the condenser 74 is not limited thereto. May be stored in the tank 44 and then transported from the water purifier 40 toward the reformer 2.

  Although the above-described embodiment is applied to a water self-supporting type system, the present invention is not limited thereto, and may be applied to a water replenishing type system that replenishes water purifier 40 or tank 44 with replenishing water such as tap water. good. The above-described embodiment is applied to a solid oxide fuel cell system. However, the present invention is not limited to this, and one or more of water vapor-containing gases of anode gas, anode off gas, and cathode off gas are condensed. Any fuel cell system having a condenser for generating condensed water may be used, and the present invention can also be applied to a solid polymer type, molten carbonate type or phosphoric acid type fuel cell system. The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope not departing from the gist.

The following technical idea can also be grasped from the above description.
[Additional Item 1] A reformer that generates anode gas by reforming a fuel raw material with reformed water, a fuel cell that generates power using the anode gas and the cathode gas, and hot water heated by the exhaust heat of the system are stored. A hot water storage tank, a condenser that cools the steam-containing gas generated by the operation of the system to generate condensed water, a hot water storage passage that supplies the hot water from the hot water tank to the condenser as cooling water, and hot water stored in the hot water tank A hot water supply source for cooling the water vapor-containing gas of the condenser by supplying it as cooling water to the passage, a reforming water tank for collecting the condensed water generated by the condenser and storing it as liquid phase reforming water, A fuel cell system comprising a reforming water conveyance source that supplies reforming water stored in a reforming water tank to a reformer. The reforming water stored in the reforming water tank can be supplied to the reformer.
[Additional Item 2] In Additional Item 1, the control unit outputs a signal for permitting activation of the system when the condition that the amount of water below a predetermined temperature in the hot water tank is equal to or greater than the predetermined amount is satisfied. Fuel cell system.
[Additional Item 3] The fuel cell system according to Additional Item 1 or 2, wherein the control unit outputs a signal for permitting activation of the system when a condition that the outside air temperature is equal to or lower than a predetermined temperature is satisfied when the system is activated.
[Additional Item 4] In Additional Items 1 to 3, when the control unit starts the system, the condition that the water level of the reforming water tank is equal to or higher than a predetermined water level (for example, the second water level such as the middle water level Mid) is satisfied. When the fuel cell system outputs a signal to allow the system to start.
[Additional Item 5] In Additional Items 1 to 4, when the control unit is performing the power generation operation of the system, when the water level of the reforming water tank is less than a predetermined water level (for example, the first water level such as the high water level High), Limit the maximum power output to W1 less than the rated power, and limit the maximum power output of the system to W1 less than the rated power when the water level of the reforming water tank is higher than the specified water level (for example, the first water level such as high water level High). A fuel cell system that will not let you.

  The present invention can be applied to, for example, stationary, vehicle, electrical equipment, electronic equipment, and portable fuel cell systems.

  In the figure, 1 is a fuel cell, 2 is a reformer, 20 is an evaporation section, 22 is a reforming section, 3 is a power generation module, 32 is a power generation chamber, 4 is a reforming water system, 40 is a water purifier, and 41 is a reformer. A quality water passage, 42 is a reforming water pump (reforming water conveyance source), 43 is a water supply valve, 44 is a reforming water tank, 5 is a fuel raw material supply system, 50 is a fuel source, 51 is a fuel raw material supply passage, 6 Is a cathode gas supply system, 60 is a cathode gas supply passage, 7 is a hot water storage system, 70 is a hot water storage tank, 70t is a temperature sensor, 70i is a water inlet, 70p is a water outlet, 71 is a hot water storage passage, 72 is a hot water storage pump (hot water storage water) (Conveying source), 74 is a condenser, 75 is an exhaust passage, 76 is an exhaust outlet, 77 is a condensed water passage, 79 is a radiator device, 79a is a radiator, 79c is a cooling fan, 100 is a control unit, 102 is a start switch, 201 is a gas temperature sensor, 202 is a water temperature sensor, 20 The outside air temperature sensor, 301 a high water level sensor, the medium is 302 level sensor, 303 denotes a low water level sensor.

Claims (6)

  A reformer that reforms a fuel raw material with reformed water to generate anode gas, a fuel cell that generates electric power using the anode gas and cathode gas, a hot water storage tank that stores hot water heated by exhaust heat of the system, A condenser that cools a steam-containing gas generated during the operation of the system to generate condensed water, a hot water storage passage that supplies water from the hot water tank as cooling water to the condenser, and water in the hot water tank is the hot water storage A hot water supply source that cools the water vapor-containing gas of the condenser by supplying it as cooling water to the passage, and a reformed water tank that collects the condensed water generated by the condenser and stores it as liquid phase reformed water A sensor for detecting the level of the reformed water stored in the reformed water tank, and a reformed water transport for supplying the reformed water stored in the reformed water tank to the reformer And start the system At least one of the first condition that the water level of the reforming water tank is equal to or higher than a predetermined water level and the second condition that the amount of water below the first predetermined temperature in the hot water storage tank is equal to or higher than a predetermined amount. A fuel cell system comprising: a control unit that permits activation of the system when a condition is satisfied.   A reformer that reforms a fuel raw material with reformed water to generate anode gas, a fuel cell that generates electric power using the anode gas and cathode gas, a hot water storage tank that stores hot water heated by exhaust heat of the system, A condenser that cools a steam-containing gas generated during the operation of the system to generate condensed water, a hot water storage passage that supplies water from the hot water tank as cooling water to the condenser, and water in the hot water tank is the hot water storage A hot water supply source that cools the water vapor-containing gas of the condenser by supplying it as cooling water to the passage, and water in the passage portion upstream of the condenser in the hot water storage passage is exhibited using outside air. A radiator device, a reformed water tank that collects the condensed water generated in the condenser and stores it as liquid phase reformed water, and detects the level of the reformed water stored in the reformed water tank With sensor A reforming water transport source that supplies the reforming water stored in the reforming water tank to the reformer, and a system level that is activated when the system is activated, the water level of the reforming water tank is equal to or higher than a predetermined water level. At least one of the first condition, the second condition that the amount of water below the first predetermined temperature in the hot water tank is a predetermined amount or more, and the third condition that the temperature of the outside air is below the second predetermined temperature. A fuel cell system comprising: a control unit that permits activation of the system when two conditions are satisfied.   In claim 1 or claim 2, when starting the system, when the water level of the reforming water tank is less than the predetermined water level, when it is determined that the condensed water generation capability in the condenser is secured, When the water level of the reformed water tank satisfies the relaxed first condition in which the first condition is relaxed, the control unit permits the system to be activated.   A reformer that reforms a fuel raw material with reformed water to generate anode gas, a fuel cell that generates electric power using the anode gas and cathode gas, a hot water storage tank that stores hot water heated by exhaust heat of the system, A condenser that cools a steam-containing gas generated during the operation of the system to generate condensed water, a hot water storage passage that supplies water from the hot water tank as cooling water to the condenser, and water in the hot water tank is the hot water storage A hot water supply source that cools the water vapor-containing gas of the condenser by supplying it as cooling water to the passage, and a reformed water tank that collects the condensed water generated by the condenser and stores it as liquid phase reformed water A sensor for detecting the level of the reformed water stored in the reformed water tank, and a reformed water transport for supplying the reformed water stored in the reformed water tank to the reformer And start the system Per the water of the reforming water tank, a fuel cell system and a control unit for activating allowed the system based on the amount of the first predetermined temperature or less of water out of the hot water storage tank.   A reformer that reforms a fuel raw material with reformed water to generate anode gas, a fuel cell that generates electric power using the anode gas and cathode gas, a hot water storage tank that stores hot water heated by exhaust heat of the system, A condenser that cools a steam-containing gas generated during the operation of the system to generate condensed water, a hot water storage passage that supplies water from the hot water tank as cooling water to the condenser, and water in the hot water tank is the hot water storage A hot water supply source that cools the water vapor-containing gas of the condenser by supplying it as cooling water to the passage, and water in the passage portion upstream of the condenser in the hot water storage passage is exhibited using outside air. A radiator device, a reformed water tank that collects the condensed water generated in the condenser and stores it as liquid phase reformed water, and detects the level of the reformed water stored in the reformed water tank With sensor In starting the system and the reforming water transport source that supplies the reforming water stored in the reforming water tank to the reformer, the first of the amount of water in the reforming water tank and the hot water storage tank. A fuel cell system comprising: a controller that permits activation of the system based on an amount of water below a predetermined temperature and the temperature of the outside air.   6. The control unit according to claim 4 or 5, wherein, when the system is started up, the control unit is more effective than the start / stop energy obtained by adding the start energy used for starting the system and the stop energy used for stopping the system. A fuel cell system that allows the system to be activated when a power generation operation time exceeding the energy saving amount when the power generation operation is performed is obtained.