JP2009277672A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage on a fuel cell system caused by freezing even when outside air temperature is low at a location where a fuel cell is mounted. <P>SOLUTION: The fuel cell system 400 includes the fuel cell 406 and a water supply line (for example, a piping 467, a water tank 411, and a water tank 412) for supplying water to the fuel cell 406. The fuel cell system 400 also includes a temperature sensor 530 for always measuring outside air temperature and a control section 455. The control section 455 determines whether the fuel cell 406 generates power. When the fuel cell 406 does not generate power, freezing prevention treatment for preventing freezing of the water in the water supply line is performed when the outside air temperature measured by the temperature sensor 530 becomes below designated temperature, for example, approximately 4°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell system.

  In recent years, fuel cells that have high energy conversion efficiency and do not generate harmful substances due to power generation reactions have attracted attention. As one of such fuel cells, a polymer electrolyte fuel cell (PEFC) that operates at a low temperature of 100 ° C. or lower is known.

  A solid polymer electrolyte fuel cell has a basic structure in which a solid polymer electrolyte membrane is disposed between a fuel electrode and an air electrode. Hydrogen is supplied to the fuel electrode and oxygen is supplied to the air electrode. This is a device that generates electricity.

Fuel ^{_{electrode: H 2 → 2H + + 2e}} - (1)
Air electrode: 1 / 2O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)
The fuel electrode and the air electrode have a structure in which a catalyst layer and a gas diffusion layer are laminated. The catalyst layers of the electrodes are arranged opposite to each other with the solid polymer electrolyte membrane interposed therebetween to constitute a fuel cell. The catalyst layer is a layer formed by binding carbon particles carrying a catalyst with an ion exchange resin. The gas diffusion layer becomes a passage for oxygen and hydrogen. The power generation reaction proceeds at a so-called three-phase interface of the catalyst, ion exchange resin and hydrogen in the catalyst layer.

  At the fuel electrode, hydrogen contained in the supplied fuel is decomposed into hydrogen ions and electrons as shown in the above formula (1). Among these, hydrogen ions move inside the solid polymer electrolyte membrane toward the air electrode, and electrons move to the air electrode through an external circuit. On the other hand, in the air electrode, oxygen contained in the oxidant supplied to the air electrode reacts with hydrogen ions and electrons that have moved from the fuel electrode, and water is generated as shown in the above formula (2). In this way, in the external circuit, electrons move from the fuel electrode toward the air electrode, so that electric power is taken out.

  In recent years, attempts have been made to use such solid polymer electrolyte fuel cells as household power sources. Patent Document 1 describes an example in which a solid polymer electrolyte fuel cell is used as a household power source. Here, as shown in FIG. 3, for example, a fuel cell power supply device A including a solid polymer electrolyte fuel cell is installed outdoors, and a raw fuel gas such as city gas is supplied to generate electric power. Is converted into alternating current, and electric power is supplied to indoor electrical equipment.

  In such a fuel cell system, since heat is generated in the fuel cell, cooling water is caused to flow through the fuel cell in order to cool the generated heat. Further, when a reformer is used to reform the hydrogen supplied to the fuel electrode, heat is also generated in the reformer, so that cooling water is also passed through the reformer. At this time, warm water is generated from city water by the exhaust heat absorbed by the cooling water using the heat exchanger. This hot water is supplied to water around indoor kitchens, washrooms, and bathrooms. Therefore, a hot water storage tank C is connected to the fuel cell system.

  City water is supplied to the hot water storage tank C, and a part of the city water is sent to a plurality of heat exchangers disposed in the fuel cell power supply device A to be heated, and this hot water is supplied to the hot water storage tank C. It is returned and stored. At the time of hot water supply, hot water is taken out from the hot water storage tank C and used for indoor water spots.

  Further, in a solid polymer electrolyte fuel cell, in a region of high current density, water flows away from the fuel electrode side due to the flow of ions in the polymer electrolyte membrane, and the membrane is dried. As a result, the output density may decrease due to an increase in electrical resistance. Therefore, moisture management is important in order to suppress the drying of the film. As an example of moisture management, a method of supplying hydrogen and oxygen to a fuel electrode and an air electrode of a fuel cell via a water tank in which water is bubbled is performed. Thereby, drying of a polymer electrolyte membrane can be avoided and the fall of output density can be suppressed.

JP 2002-216810 A

  However, for example, in the fuel cell system of DSS (Daily Start Stop) method that stops the operation of the fuel cell system at night, the WSS (Weekly Start Stop) method of stopping the operation of the fuel cell system on the weekend, or at the end of the year and the beginning of the year If the outside air temperature decreases when the battery system is not operated, water in the water pipe or water tank used as cooling water may freeze. In such a case, piping may burst. In addition, the container that houses the fuel cell may burst. Furthermore, if the polymer electrolyte membrane is frozen, the performance may be degraded even if it is subsequently thawed.

  In view of such circumstances, the present invention provides a technology capable of preventing damage to the fuel cell system due to freezing of the water supply line supplied to the fuel cell system even when the outside air temperature at the place where the fuel cell is installed is low. The purpose is to provide.

  One embodiment of the present invention is a fuel cell system. The fuel cell system is a fuel cell system including a fuel cell and a water supply line that supplies water to the fuel cell, and an outside air temperature measurement unit that measures an outside air temperature at a place where the fuel cell is installed; When the outside air temperature measured by the outside air temperature measurement unit is less than or equal to a predetermined temperature when it is determined whether the fuel cell is generating electricity and it is determined that the fuel cell is not generating electricity, A control unit that performs anti-freezing processing for preventing freezing of water in the water supply line, and the control unit starts power generation of the fuel cell when the outside air temperature becomes equal to or lower than the predetermined temperature. Features.

  Here, the predetermined temperature may be a temperature at which water may freeze at that temperature, or a temperature that is several degrees higher than the temperature. The predetermined temperature may be about 4 ° C., for example. Here, the start of power generation can include, in addition to power generation of the fuel cell itself, introduction of fuel gas, start of fuel gas reforming, start of air supply, and the like. Further, as the antifreezing treatment, it is sufficient to generate the fuel cell to such an extent that the power generation amount of the fuel cell is minimized. In this way, freezing of water in the water supply line can be prevented even when the outside air temperature of the fuel cell system falls below a predetermined temperature. In addition, if the predetermined temperature is set to a temperature that is several degrees higher than the temperature at which water may freeze, it may take time to actually perform the freeze prevention process after the freeze prevention process start command is issued. Even if it exists, freezing of the water supply line of a fuel cell system can be prevented. Here, the fuel cell main body may be provided in the casing, and in this case, the outside air temperature at the place where the fuel cell is installed can be a temperature outside the casing. The fuel cell system may be installed in a building such as a boiler room. In this case, the outside air temperature at the place where the fuel cell is installed may be the temperature inside the building such as the boiler room.

  In the fuel cell system of the above aspect, the control unit can control the power generation amount of the fuel cell according to the outside air temperature.

  For example, when the outside air temperature is low, the control unit can increase the power generation amount of the fuel cell. In this way, even if the outside air temperature is low, freezing of water in the water supply line of the fuel cell system can be prevented, and damage to the fuel cell system can be prevented.

  In the fuel cell system of the above aspect, the control unit can supply water to the water supply line when the outside air temperature becomes equal to or lower than a predetermined temperature.

  By continuously supplying water to the water supply line, freezing of water in the water supply line can be prevented even if the outside air temperature is equal to or lower than a predetermined temperature.

  The fuel cell system of the above aspect can further include a cooling unit that cools heat generated from the fuel cell, and the water supply line can supply water to the cooling unit.

  Here, the cooling unit can be configured to cool either one or both of the air electrode and the fuel electrode of the fuel cell.

  The fuel cell system according to the aspect described above may further include a reformer that reforms the raw fuel gas into a reformed gas containing hydrogen, and a cooling unit that cools heat generated from the reformer. The line can supply water to the cooling section.

  In the fuel cell system of the above aspect, the fuel cell may be a solid polymer fuel cell including a solid polymer electrolyte membrane, and a fuel electrode and an air electrode provided with the solid polymer electrolyte membrane interposed therebetween, The water supply line can supply water to a water tank that humidifies fuel and air supplied to the fuel electrode and the air electrode, respectively.

  The fuel cell system of the above aspect can further include a heater disposed in the water supply line, and the control unit can turn on the heater when the outside air temperature becomes a predetermined temperature or lower.

  Here, the fuel cell can be accommodated in the housing, and in this case, the heater can be disposed on the water supply line provided on the outside of the housing and on the side close to the outside of the housing. . Further, the heater may be disposed in the drainage line, and the control unit can turn on the heater provided in the drainage line when the outside air temperature becomes a predetermined temperature or lower.

  The fuel cell system of the above aspect may further include a heat exchanger that recovers heat generated from the fuel cell and heats water introduced from the outside.

  In this way, the fuel cell system of the above aspect is a cogeneration type that collects steam / hot water discharged from a fuel gas reforming device or a fuel cell, and uses it for air conditioning, hot water supply, and various other things. It can be a fuel cell system.

  The fuel cell system of the above aspect may further include a power storage unit or a power consumption unit. Here, the power consuming unit may be a heater installed in a hot water storage tank that stores heat discharged from the fuel cell system as hot water, or a heater for heating water supplied to the hot water storage tank. In addition, it can also be set as the dummy heater for using up the electric power which generate | occur | produced when performing the freeze prevention process. For example, in a cold district where snow is accumulated, the heating means for melting snow can be used as the power consuming part.

  According to this aspect, there is provided a method for operating a fuel cell system including a fuel cell and a water supply line that supplies water to the fuel cell, wherein the fuel cell generates power in the fuel cell system. When the outside air temperature of the place where the fuel cell is installed falls below a predetermined temperature when the fuel cell is not installed, the fuel cell system is operated to prevent freezing of the water in the water supply line. A method is provided.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention among methods, apparatuses, systems, etc. are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, even when outside temperature is low, the technique which can prevent the failure | damage of a fuel cell system by freezing etc. of the water supply line supplied to a fuel cell system can be provided.

1 is a block diagram showing a fuel cell system according to an embodiment of the present invention. It is a flowchart which shows the procedure of the freeze prevention process by a control part. It is a figure which shows the example which used the solid polymer electrolyte fuel cell as household power supply.

  FIG. 1 is a diagram showing a configuration of a fuel cell system according to an embodiment of the present invention.

The fuel cell system 400 according to the present embodiment is disposed in a housing as shown in FIG. 3 described above, or an apartment house such as an apartment or a condominium.

  The fuel cell system 400 includes a fuel cell 406 of a solid polymer electrolyte fuel cell. The fuel cell system 400 also adopts a cogeneration system that effectively uses the heat generated in the power generation of the fuel cell 406. As a configuration for that purpose, the fuel cell system 400 includes a hot water storage tank 501.

  In addition to the fuel cell 406 and the hot water storage tank 501, the fuel cell system 400 includes a fuel supply source 401, a desulfurizer 402, a reformer 413, an air supply source 430, a water tank 411, a water tank 412, Water treatment device 509, water supply source 510, water tank 507, heat recovery heat exchanger 503, heat recovery heat exchanger 505, heater 513, power exchange device 457, control unit 455, A system 459, a temperature sensor 530, and a power storage unit 532 are included.

  The fuel supply source 401 supplies a fuel gas such as natural gas, city gas, methanol, LPG, or butane as a fuel supply source of the fuel cell 406. The desulfurizer 402 removes sulfur components from the fuel gas. The reformer 413 includes a reformer 403, a CO converter 404, and a CO remover 405. The reformer 403 generates a reformed gas containing hydrogen, carbon dioxide, and carbon monoxide from the fuel gas. Here, although not shown, since the chemical reaction in the reformer 403 is an endothermic reaction, it is preferable to provide a burner in the reformer 403 and perform the chemical reaction while always heating.

  The CO converter 404 converts carbon monoxide contained in the reformed gas generated by the reformer 403 into carbon dioxide. The CO remover 405 removes unmodified carbon monoxide in the gas transformed by the CO transformer 404. Although not shown here, since the CO converter 404 and the CO remover 405 perform an exothermic reaction, the CO converter 404 and the CO remover 405 are also provided with a cooling unit that cools the heat generated by the exothermic reaction. You can also.

  The fuel supply source 401 and the desulfurizer 402 are connected by a gas pipe 417. The gas pipe 417 is provided with an electromagnetic open / close valve 418 and a booster pump 419. Further, the desulfurizer 402 and the reformer 413 are connected by a gas pipe 422. Here, although not shown, in the reformer 413, the reformer 403, the CO converter 404, and the CO remover 405 are each connected by a gas pipe.

  The fuel cell 406 includes a fuel electrode 406a and an air electrode 406b. The fuel cell 406 reacts the reformed gas and oxygen to generate electric power. Hydrogen (reformed gas), which is a fuel, is supplied to the fuel electrode 406a, and oxygen in the air is supplied to the air electrode 406b. As a result, an electrochemical reaction occurs in the fuel cell 406, and electric power can be taken out. The electric power extracted from the fuel cell 406 is transmitted to the power exchange device 457 via the wiring 434.

  In the electrochemical reaction performed in the fuel cell 406, heat is generated by the activation overvoltage, concentration overvoltage, and resistance overvoltage. Therefore, in fuel cell system 400 in the present embodiment, fuel cell 406 further includes a cooling unit 406c that cools the heat generated in air electrode 406b.

  The reformed gas reformed by the reformer 413 is supplied to the fuel electrode 406a via the pipe 424. Here, as described above, in order to avoid drying of the polymer electrolyte membrane of the fuel cell 406, the reformed gas is supplied to the fuel electrode 406a after passing through the water tank 411. In addition, oxygen in the air is supplied to the air electrode 406 b from the air supply source 430 through the pipe 431 and the pipe 432. Again, in order to avoid drying of the polymer electrolyte membrane of the fuel cell 406, oxygen is supplied to the air electrode 406b after passing through the water tank 412. The air electrode 406 b is connected to the heat recovery heat exchanger 503 via the pipe 469. An exhaust duct and a drain water pipe (both not shown) are connected to the heat recovery heat exchanger 503. The reformed gas from the fuel electrode 406a is circulated again to the reformer 403 (a burner provided in the reformer 403) and used as a heat source.

  Water is supplied from the water tank 412 to the cooling unit 406c through the booster pump 463 and the pipe 471. Here, the cooling unit 406c is configured to cool the air electrode 406b, but the cooling unit 406c may be configured to cool the fuel electrode 406a. In this case, the cooling unit 406c can be configured to be supplied with water from the water tank 411 via a booster pump. Further, both the fuel electrode 406a and the air electrode 406b can be cooled. The water that has passed through the cooling unit 406 c is introduced into the heat recovery heat exchanger 505 through the pipe 465. The water introduced into the heat recovery heat exchanger 505 passes through the heat recovery heat exchanger 505 and returns to the water tank 412. Although not shown, a drain water pipe may be connected to the pipe 567. Further, this drain water pipe may be connected to the pipe 461.

  The water treatment device 509 performs a process for converting the city water supplied from the water supply source 510 into pure water. The water tank 507 stores the pure water treated in the water treatment device 509. The pure water treated in the water treatment device 509 is transferred to the water tank 411 and the water tank 412 via the pipe 467 by the booster pump 520. The water tank 507 and the reformer 413 are connected by a pipe 522 provided with a booster pump 524, and pure water from the water tank 507 is supplied to the reformer 413. Further, water from the water supply source 510 is also supplied to the hot water storage tank 501 through the water pipe 515.

  The hot water storage tank 501 is connected to the heat recovery heat exchanger 503 by the booster pump 446 via the hot water pipe 443, and is connected to the heat recovery heat exchanger 505 by the booster pump 445 via the hot water pipe 442. Yes. The temperature of the air led out from the air electrode 406b to the pipe 469 is increased by the exothermic reaction of the fuel cell 406, and the exhaust air whose temperature has been increased is recovered by the heat recovery heat exchanger 503. As a result, the water circulated from the hot water storage tank 501 is warmed and returned to the hot water storage tank 501 via the hot water pipe 443. Similarly, the water passing through the cooling unit 406c absorbs heat generated during power generation and rises in temperature. The water that has risen in temperature is introduced into the heat recovery heat exchanger 505 via the hot water pipe 442. Heat exchange with water from the hot water storage tank 501 is performed. Therefore, the temperature of the water in the hot water storage tank 501 rises and the temperature of the water in the water tank 412 falls. As a result, the water in the water tank 412 can circulate through the cooling unit 406c to cool the fuel cell 406. In addition, since the temperature of the water in the hot water storage tank 501 can be raised by using heat generated during power generation, hot water is generated from city water using this heat, Can be supplied to kitchens.

  Power exchange device 457 includes a boost converter and an inverter. The boost converter boosts the electric power generated by the fuel cell 406 to a voltage necessary for the inverter. Power from the inverter is sent to the system 459 and the power storage unit 532.

  The system 459 is supplied to a home via electric wiring (not shown) as a single-phase three-wire 100V / 200V power source, for example. Further, the inverter of the power exchange device 457 is also electrically connected to the hot water storage tank 501.

  The temperature sensor 530 is provided outside the main body of the fuel cell system 400 and measures the outside air temperature around the place where the fuel cell system 400 is provided. When the fuel cell system 400 is installed outdoors, the temperature sensor 530 measures the outdoor temperature.

For example, when the fuel cell system 400 is provided in the boiler chamber, the temperature sensor 530 is provided in the boiler chamber. Further, the temperature sensor 530 may be provided in the hot water storage tank 501. During the operation of the fuel cell 406, the temperature in the housing 534 of the fuel cell system 400 rises to about 60 ° C., so that it is not always necessary to provide the heater 513, but for example, a water pipe 515 from the water supply source 510 or water Pipes and devices connected to the outside of the housing 534, such as water supply lines such as the tank 507, water treatment device 509, piping 522, drain water piping from the reforming device 413, piping provided near the outside of the housing 534, It is preferable to provide a heater 513 in the apparatus or the like. Normally, water begins to freeze at 0 ° C, but when the wind blows, the heat of vaporization on the surface of the water is deprived even when the wind blows, and the freezing starts from the surface. . For this reason, it is preferable to provide a heater 513 because the drain water pipe or the like is likely to condense even at about 4 ° C.

  Based on the temperature of the temperature sensor 530, the control unit 455 performs anti-freezing processing for preventing freezing of the water supply line such as piping of the fuel cell system 400 when the outside air temperature becomes a predetermined temperature or lower. As anti-freezing processing, (i) start of power generation of the fuel cell 406, (ii) start of water supply, (iii) switch on of the heater 513, etc. can be performed. The power storage unit 532 can be a secondary battery that stores the power generated by the fuel cell 406 during the freeze prevention process. The power stored in this way can be used for commercial power or a dummy heater. Further, the stored electric power can be used when the load fluctuation among the electric power consumed in the home is severe and the output fluctuation of the fuel cell system 400 cannot follow the load fluctuation. Note that power may be directly supplied to a dummy heater or the like instead of the power storage unit 532. In particular, in cold regions where snow is accumulated, the electric power generated during the freeze prevention process can be used as a power source for the heating means for melting snow. This electric power can also be used as an electric power source for heating the heater 513 or driving a booster pump, for example.

  FIG. 2 is a flowchart showing the procedure of the freeze prevention process by the control unit 455.

First, the control unit 455 determines whether or not the fuel cell system 400 is in a normal operation state (S10). The normal operation of the fuel cell system 400 means that the power generation processing of the fuel cell 406 is performed, for example, during the daytime. When the fuel cell system 400 is in a normal operation state (Yes in S10), the control unit 455 ends the freeze prevention process. When the fuel cell system 400 is not in a normal operation state (No in S10), the control unit 455 determines whether or not the outside air temperature is equal to or lower than a predetermined temperature based on the temperature measured by the temperature sensor 530 (S12). Here, the predetermined temperature is not particularly limited, but can be set to 4 ° C., for example. This is because water begins to freeze at such a temperature. In addition, as will be described later, the control unit 455 issues a command to start the freeze prevention process. However, after the command to start the freeze prevention process is performed, a certain amount of time is required until the process for actually preventing the freeze is started. The predetermined temperature may be higher than 4 ° C. because a period may be required.

  In step 12, when the outside air temperature is equal to or lower than the predetermined temperature (Yes in S12), the control unit 455 issues a command to start the freeze prevention process (S14). For example, the control unit 455 controls the power exchange device 457 to start the power generation of the fuel cell 406.

Further, the control unit 455 controls the booster pump 520 and the booster pump 463 to start supplying the cooling water to the cooling unit 406c. In addition, the control unit 455 turns on the heater 513 to heat the water tank 507, the water treatment device 509, the pipe 522, and the like.

  At this time, the control unit 455 can control, for example, the power generation amount (output) of the fuel cell 406, the flow rate of cooling water, and the heating temperature of the heater according to the outside air temperature. The control unit 455 preferably performs control so that the lower the outside air temperature is, the higher the power generation amount of the fuel cell 406, the higher the flow rate of the cooling water, and the higher the heating temperature of the heater. Note that only one of the processes (i) to (iii) can be performed, but can be performed in appropriate combination. In this case, for example, the power generated by the fuel cell 406 can be used as a power source for heating the heater 513 or a power source for driving pumps such as the boost pump 520 and the boost pump 463. Further, in the freeze prevention process, when excessive power is generated, it can be stored in the power storage unit 532 or a dummy resistor such as a dummy heater can be provided to consume power.

  In step 12, if the outside air temperature is not lower than the predetermined temperature (No in S12), the freeze prevention process is terminated. The control unit 455 performs the freeze prevention process until a predetermined condition is satisfied (Yes in S16). The predetermined condition may be, for example, when a predetermined time has elapsed from the start of the freeze prevention process or when the outside air temperature measured by the temperature sensor 530 is equal to or higher than a predetermined temperature. If the predetermined condition is satisfied (Yes in S16), the freeze prevention process is terminated, but the temperature sensor 530 always measures the outside air temperature, and the control unit 455 performs the freeze prevention process shown in FIG. Make a decision.

  The freeze prevention process can be performed continuously for a certain long period of time, but can also be performed intermittently, for example, at relatively short intervals. In this case, the control unit 455 can perform control such as changing the interval of the intermittent freeze prevention process according to the outside air temperature measured by the temperature sensor 530. For example, when the outside air temperature is about 0 ° C., the freeze prevention process is intermittently performed, but when the outside air temperature falls to about −20 ° C., the freeze prevention process may be continuously performed. As a freeze prevention process, when generating power from a fuel cell, it takes a long time from the introduction of the fuel gas in the fuel supply source 401 until the power is actually taken out from the fuel cell 406, and a relatively large amount of energy is required at startup. For reasons such as necessity, it may be preferable to perform anti-freezing treatment continuously in cold regions where the outside air temperature is always below a predetermined temperature.

  Next, the operation in the normal operation state when the fuel cell system 400 is operated will be described.

When the operation of the fuel cell system 400 is started, fuel gas from the fuel supply source 401 enters the booster pump 419 via the electromagnetic on-off valve 418, is boosted by the booster pump 419, and is supplied to the desulfurizer 402. . In the desulfurizer 402, sulfur components are removed from the fuel gas. When a catalyst utilizing an adsorption reaction such as activated carbon is used for the desulfurizer 402, the sulfur component can be removed at room temperature. The fuel gas that has passed through the desulfurizer 402 is supplied to the reformer 403 of the reformer 413 via the gas pipe 422. In the reformer 403, a reformed gas containing hydrogen, carbon dioxide, and carbon monoxide is generated.

  The gas that has passed through the reformer 403 is supplied to a CO converter 404, where carbon monoxide contained in the reformed gas is converted into carbon dioxide. The gas that has passed through the CO converter 404 is supplied to the CO remover 405, and unconverted carbon monoxide in the gas that has passed through the CO converter 404 is removed. Hydrogen after carbon monoxide removed through the CO remover 405 is supplied to the fuel electrode 406 a of the fuel cell 406 through the gas pipe 423, the water tank 411, and the pipe 424.

  On the other hand, the air supplied from the air supply source 430 is supplied to the air electrode 406b via the water tank 412. As a result, hydrogen supplied to the fuel electrode 406a and oxygen supplied to the air electrode 406b react to generate electric power. At this time, water partially generated by the chemical reaction and remaining in the fuel electrode 406a and drain water generated in the reformer 413 are discharged to the outside through a drain water pipe (not shown). Further, the exhaust gas generated by the chemical reaction is discharged to the outside through an exhaust duct (not shown).

  At this time, the temperature of the water in the hot water storage tank 501 rises due to heat exchange in the heat exchanger for heat recovery 503 and the heat exchanger for heat recovery 505. In addition, since the water generated in the chemical reaction of the fuel cell 406 exists as water vapor in the exhaust air whose temperature has increased, heat is exchanged with the water circulated from the hot water storage tank 501 in the heat recovery heat exchanger 503. At this time, the water is condensed and discharged as drain water to the outside through a drain water pipe (not shown).

  In the present embodiment, even when the outside air temperature becomes equal to or lower than the predetermined temperature, the antifreezing process is performed so that the water supplied to the fuel cell system 400 is not frozen. Damage can be prevented. Furthermore, the electric power generated during the freeze prevention process can also be effectively used for various applications, and energy saving can be realized. Further, since the fuel cell system 400 takes the form of a cogeneration system, energy can be effectively used. Therefore, high overall thermal efficiency can be obtained, so that the amount of raw fuel consumed can be reduced and the amount of carbon dioxide emitted can be reduced.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are within the scope of the present invention. . Such an example is described below.

  In the above embodiment, an example in which the fuel cell system 400 is stopped during non-normal operation and the freezing prevention process is performed when the outside air temperature becomes a predetermined temperature or lower has been described. In an area where water is always frozen at night, the fuel cell system 400 is operated even during non-normal operation, and the operation of the fuel cell system 400 is performed when the outside air temperature exceeds a predetermined temperature. It is also possible to perform processing of a procedure that stops the process.

  In the above embodiment, an example has been described in which the outside temperature is constantly measured by the temperature sensor 530 and the freeze prevention process is performed when the outside temperature falls below a predetermined temperature. However, the temperature sensor 530 is necessarily provided. However, depending on the season and region, the freeze prevention process can be performed at a predetermined time.

  In addition, for example, the fuel cell system 400 installed in each of a plurality of households is connected via a network, and setting of a control method and the like when performing anti-freezing processing as shown in FIG. It can also be.

  Although not shown in the above embodiment, a heat exchanger (not shown) may be connected to the exhaust system of the reformer 403, and the water in the water tank 507 is supplied via the booster pump 524. The steam may be vaporized by a heat exchanger, and the steam may be mixed with raw fuel and supplied to the reformer 403. Further, when the reformer 403 is provided with a burner, the combustion exhaust gas from the burner of the reformer 403 can also be used for heat exchange.

  In the above embodiment, the air electrode 406b and the cooling unit 406c have been supplied with water from the water tank 412, but these may be supplied separately, in which case the cooling unit As the cooling water supplied to 406c, for example, an antifreeze containing an electrolyte or the like can be used.

  The antifreezing treatment of water inside the water tank 507, the water treatment device 509, the water tank 411, the water tank 412 and the like can be performed by providing a stirrer in these devices and stirring the water.

  Furthermore, the temperature sensor 530 may be provided, for example, in a pipe or the like in the housing in which the fuel cell 406 is accommodated. When the temperature of that portion falls below a predetermined temperature, the temperature sensor 530 performs a freeze prevention process. You may do it.

  In the above embodiment, it has been described that the reformed gas obtained by reforming the fuel gas by the reformer 413 is supplied to the fuel cell 406. However, the fuel cell system 400 does not include the reformer 413. It can also be set as a structure and hydrogen gas may be supplied directly.

400 fuel cell system, 401 fuel supply source, 402 desulfurizer, 403 reformer, 404 CO converter, 405 CO remover, 406 fuel cell, 406a fuel electrode, 406b air electrode, 406c cooling unit, 411 water tank, 412 Water tank, 413 reformer, 417 gas pipe, 418 electromagnetic on-off valve, 419 boost pump, 422 gas pipe, 423 gas pipe, 424 piping, 430 air supply source, 431 piping, 432 piping, 434 wiring, 442 hot water piping, 443 Hot water piping, 445 boosting pump, 446 boosting pump, 455 control unit, 457 power exchange device, 459 system, 461 piping, 463 boosting pump, 465 piping, 467 piping, 469 piping, 471 piping, 501 hot water storage tank, 503 heat recovery Heat exchanger, 505 Heat exchange for heat recovery Vessel, 507 water tank, 509 water treatment device, 510 water supply source, 513 a heater, 515 water pipes, 520 boost pump, 522 pipe, 524 boost pump, 530 temperature sensor, 532 power storage unit, 534 housing, 567 pipe.

Claims (7)

A fuel cell system including a fuel cell and a water supply line for supplying water to the fuel cell,
An outside air temperature measuring unit for measuring the outside air temperature at a place where the fuel cell is installed;
When it is determined whether or not the fuel cell is generating power, and it is determined that the fuel cell is not generating power, the outside air temperature measured by the outside air temperature measurement unit becomes a predetermined temperature or less. And a control unit for performing anti-freezing processing for preventing freezing of water in the water supply line;
With
The said control part starts the electric power generation of the said fuel cell, when the said external temperature becomes below the said predetermined temperature, The fuel cell system characterized by the above-mentioned. The fuel cell system according to claim 1,
The said control part controls the electric power generation amount of the said fuel cell according to the said external temperature, The fuel cell system characterized by the above-mentioned. The fuel cell system according to claim 1 or 2,
The said control part supplies the said water to the said water supply line when the said external temperature becomes below the said predetermined temperature, The fuel cell system characterized by the above-mentioned. The fuel cell system according to any one of claims 1 to 3,
A cooling unit for cooling heat generated from the fuel cell;
The fuel cell system, wherein the water supply line supplies water to the cooling unit. The fuel cell system according to any one of claims 1 to 4,
A reformer that reforms the raw fuel gas into a reformed gas containing hydrogen;
A cooling unit that cools the heat generated from the reformer,
The fuel cell system, wherein the water supply line supplies water to the cooling unit. The fuel cell system according to any one of claims 1 to 5,
The fuel cell is a solid polymer type fuel cell including a solid polymer electrolyte membrane, and a fuel electrode and an air electrode provided with the solid polymer electrolyte membrane interposed therebetween,
The water supply line supplies water to a water tank that humidifies fuel and air supplied to the fuel electrode and the air electrode, respectively. The fuel cell system according to any one of claims 1 to 6,
Further comprising a heater disposed in the water supply line;
The said control part turns on the said heater when the said external temperature becomes the said predetermined temperature or less, The fuel cell system characterized by the above-mentioned.

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