JP2015099712A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system using water capable of improving water recovery capability.SOLUTION: The fuel cell system includes: a fuel cell that generates the power using a hydrogen containing gas; and a water supply path that supplies water collected from a flue gas discharged from a combustion unit of the fuel cell, which burns the fuel containing no off-gas, to at least any one of a vapor generator that generates water vapor used for reforming reaction and a humidifier for humidifying a reactant gas to be supplied to the fuel cell.

Description

  The present invention relates to a fuel cell system.

  The fuel cell system usually includes a reformer that generates a hydrogen-containing gas from natural gas or LPG, which is a general raw material infrastructure.

  In the reformer, a steam reforming reaction is generally used. This steam reforming reaction is performed, for example, by reacting city gas as a raw material and steam at a high temperature of about 600 ° C. to 700 ° C. using a noble metal-based reforming catalyst such as Ni-based or Ru-based. It generates hydrogen-containing gas as the main component.

  The generated hydrogen-containing gas is supplied to the fuel cell and reacted with an oxidant gas such as air supplied separately to generate electric power and heat.

  By the way, the water used for the steam reforming reaction needs to have high purity so as not to deteriorate the catalyst in the reformer. If this water is continuously supplied from infrastructure such as tap water, a large amount of ion exchange resin is required to make the water pure with ion exchange resin, and the cost of the fuel cell system increases.

  Therefore, a fuel cell system has been proposed in which water generated in the fuel cell system is recovered and used as water for the steam reforming reaction. (For example, refer to Patent Document 1).

  FIG. 8 is a conceptual diagram showing a schematic configuration of the fuel cell system of Patent Document 1. In this configuration, the hydrogen-containing gas generated by the hydrogen generator is supplied to the fuel cell 1. A separate oxidant gas is supplied to the fuel cell 1. In the fuel cell 1, the hydrogen-containing gas and the oxidant gas react to generate electricity and heat. The oxidant gas that has not been used for this reaction is discharged from the fuel cell 1 as off-oxidant gas. The off-oxidant gas contains water produced as a vapor when hydrogen and oxygen react in the fuel cell 1. The off-oxidant gas is cooled by the condenser 2 to condense the water vapor and recover the water.

JP 2008-234869 A

  In the fuel cell system disclosed in Patent Document 1, exhaust heat recovery water for recovering heat generated in the fuel cell is generally used as the refrigerant in the condenser. This exhaust heat recovery water is stored in a hot water storage tank, and high temperature water recovered from the fuel cell system is supplied to the upper part of the hot water storage tank, and low temperature water for recovering exhaust heat is supplied to the fuel cell system from the lower part of the hot water storage tank. This makes it possible to recover heat from the fuel cell system using low temperature water and store it as hot water in a hot water storage tank.

Here, when the temperature of the exhaust heat recovery water supplied from the lower part of the hot water storage tank becomes high, water cannot be sufficiently recovered by the condenser. In the fuel cell system, water for humidifying the hydrogen-containing gas supplied to the fuel cell, water for humidifying the oxidant gas supplied to the fuel cell, and a reforming reaction for generating the hydrogen-containing gas are used. If a large amount of water, such as the water used, is used and the amount of water recovered in the fuel cell system decreases, the amount of water recovered relative to the amount of water used in the fuel cell system will be insufficient, and the water balance will not be established. He had the problem of being unable to become independent.

  The present invention has been made in view of the above problems, and an object of the present invention is to improve water self-supporting performance as compared with the conventional fuel cell system.

  In the fuel cell system, the present inventors use water contained in combustion exhaust gas discharged from a combustion apparatus that burns using fuel that does not contain fuel cell off-gas as water necessary for operation of the fuel cell system. We discovered that it was possible and intensively studied how to use it. As a result, the following knowledge was obtained.

  The fuel cell system cools and recovers water by exchanging off-oxidant gas discharged from the cathode and off-fuel gas discharged from the anode through a heat exchanger and exchanging heat with exhaust heat recovery water or the like. However, since the conventional fuel cell system recovers water only by cooling by heat exchange even when the temperature of the exhaust heat recovery water becomes high, the cooling capacity of the off-oxidant gas or off-fuel gas is reduced, and the off-oxidant gas It was difficult to recover the amount of water necessary for operation of the fuel cell system because water vapor in the gas and off-fuel gas could not be condensed.

  That is, in order to solve the above-described problem, a fuel cell system of the present invention includes a fuel cell that generates power using a hydrogen-containing gas and a combustion exhaust gas of a combustion device that burns using fuel that does not include off-gas of the fuel cell. A water supply path for supplying the recovered water to at least one of a steam generator for generating water vapor used for the reforming reaction and a humidifier for humidifying the reaction gas supplied to the fuel cell;

  The fuel cell system according to the present invention has the above-described characteristics, and thus has an effect that the water recovery capability can be improved as compared with the conventional fuel cell system using water.

FIG. 1 is a conceptual diagram illustrating an example of a schematic configuration of a fuel cell system according to the first embodiment. FIG. 2 is a conceptual diagram showing an example of a schematic configuration of the fuel cell system according to the second embodiment. FIG. 3 is a conceptual diagram showing an example of a schematic configuration of a fuel cell system according to the third embodiment. FIG. 4 is a conceptual diagram showing an example of a schematic configuration of a fuel cell system according to the fourth embodiment. FIG. 5 is a conceptual diagram illustrating an example of a schematic configuration of a fuel cell system according to a first modification of the fourth embodiment. FIG. 6 is a conceptual diagram illustrating an example of a schematic configuration of a fuel cell system according to a second modification of the fourth embodiment. FIG. 7 is a conceptual diagram showing an example of a schematic configuration of a fuel cell system according to the fifth embodiment. FIG. 8 is a conceptual diagram showing a schematic configuration of the fuel cell system of Patent Document 1.

(First embodiment)
The fuel cell system according to the first embodiment reforms water recovered from the combustion exhaust gas of a fuel cell that generates power using hydrogen-containing gas and a combustion device that burns using fuel that does not contain off-gas of the fuel cell. A steam generator that generates water vapor used in the reaction, and a water supply path that supplies at least one of a humidifier that humidifies the reaction gas supplied to the fuel cell.

  With this configuration, combustion of a combustion apparatus that burns using fuel that does not contain off-gas of the fuel cell, compared to the case where water in the off-gas or off-oxidant gas of the fuel cell is condensed by a condenser alone and water is recovered. By supplying the water recovered from the exhaust gas to the steam generator and humidifier, the amount of water recovered as the fuel cell system is increased, and the water self-supporting performance is improved.

[Device configuration]
FIG. 1 is a conceptual diagram showing an example of a schematic configuration of the fuel cell system according to the first embodiment.

  In the example shown in FIG. 1, the fuel cell system of this embodiment includes a fuel cell 1 and a water supply path 3.

  The fuel cell 1 generates power using a fuel gas containing hydrogen and an oxidant gas containing oxygen. The fuel cell 1 may be of any type, and examples thereof include solid polymer fuel cells, solid oxide fuel cells, and phosphoric acid fuel cells. The fuel gas that has not been used for power generation in the fuel cell 1 is discharged from the fuel cell 1 as off-fuel gas. The oxidant gas that has not been used for power generation in the fuel cell 1 is discharged from the fuel cell 1 as an off-oxidant gas. The fuel gas used in the fuel cell 1 may be a hydrogen-containing gas generated by reforming a hydrocarbon such as city gas or LPG with a reformer, and may be an infrastructure, a cylinder, a tank, etc. It may be a hydrogen-containing gas supplied from.

The water supply path 3 generates water vapor used for the reforming reaction from the water recovered from the combustion exhaust gas of the combustion apparatus that burns using fuel that does not contain off-fuel gas or off-oxidant gas discharged from the fuel cell 1. This is a flow path for supplying to at least one of a steam generator for humidifying and a humidifier for humidifying a reaction gas supplied to the fuel cell 1.
The fuel that does not include off-fuel gas or off-oxidant gas is, for example, city gas or hydrocarbon fuel such as LPG. Any fuel may be used as long as it generates water during combustion.

  A combustion device that burns using a fuel that does not contain off-fuel gas or off-oxidant gas is a device that supplies heat for hot water supply or heating, which is an external heat load, by combustion heat. For example, boilers, such as a water heater and a hot water heater, are mentioned. The combustion apparatus may be any apparatus as long as it burns fuel that does not contain off-fuel gas or off-oxidant gas. The combustion exhaust gas discharged from the combustion apparatus is cooled by heating water or the like, and water is condensed. In general, the condensed water is drained without being used. In this embodiment, the water self-supporting performance of the fuel cell system is improved by reusing the water. Water recovered from the combustion exhaust gas is used in at least one of a steam generator and a humidifier.

The steam generator is a device that generates water vapor used in a reforming reaction for generating fuel gas used for power generation in the fuel cell 1. The reforming reaction may take any form, and examples thereof include a steam reforming reaction, an autothermal reaction, and a partial oxidation reaction. Although not shown, equipment necessary for each reforming reaction is provided as appropriate.
The humidifier is a device that humidifies fuel gas and oxidant gas, which are reaction gases supplied to the fuel cell 1. Any material can be used as long as at least one of the fuel gas and the oxidant gas can be humidified. For example, there is an apparatus that can move water vapor or water, such as a hollow fiber membrane, by flowing one containing fuel gas or oxidant gas on one side and water supplied from the water supply path 3 on the other side. Move the water.

[Operation]
Hereinafter, the operation of the fuel cell system will be described with reference to FIG.

  In a combustion apparatus that burns using fuel that does not contain off-fuel gas or off-oxidant gas discharged from the fuel cell 1, combustion is performed constantly or intermittently. The combustion exhaust gas generated by combustion contains water vapor, and the combustion exhaust gas is cooled by heating the water used for heating and hot water supply using the heat of the combustion exhaust gas. Thereby, the water vapor contained in the combustion exhaust gas is condensed and recovered as water. The recovered water is supplied to the steam generator or the humidifier via the water supplier 4.

  The recovered water may be stored to some extent and then supplied to a steam generator or a humidifier, or the generated condensed water may be supplied to the water supply path 3 as it is.

  The water supplied to the steam generator or the humidifier is used for generation of fuel gas used for power generation of the fuel cell 1, humidification of the fuel gas, or humidification of the oxidant gas. In this way, the water collected from the combustion device that burns using the fuel that does not contain off-fuel gas or off-oxidant gas is used for power generation in the fuel cell 1, thereby improving the water self-supporting performance of the fuel cell system. Help to improve.

(Second Embodiment)
The fuel cell system of the second embodiment is the fuel cell system of the first embodiment, and is configured to supply recovered water from the exhaust gas in the fuel cell system to at least one of the steam generator and the humidifier, A water supply device that controls the amount of water flowing to at least one of the steam generator and the humidifier through the water supply channel, and when the recovered water amount decreases, the water supply device is controlled to control at least one of the steam generator and the humidifier. And a controller for replenishing water supplied to one side.

  With this configuration, it becomes possible to use the recovered water from the exhaust gas through the water supply channel only when the amount of water that can be recovered by the fuel cell system is reduced, and to reduce the amount of recovered water from the exhaust gas as much as possible. Is possible.

  The fuel cell system of the present embodiment may be configured in the same manner as the fuel cell system of the first embodiment except for the above features.

[Device configuration]
FIG. 2 is a conceptual diagram showing an example of a schematic configuration of the fuel cell system according to the second embodiment.

  In the example shown in FIG. 2, the fuel cell system of the present embodiment includes a fuel cell 1, a water supply path 3, a water supply device 4, and a controller 5.

  Since the fuel cell 1 and the water supply path 3 are the same as those in the first embodiment, description thereof will be omitted.

The water supply device 4 flows the water collected from the combustion exhaust gas of the combustion apparatus that burns using the fuel that does not contain off-gas of the fuel cell 1 through the water supply path 3 to at least one of the steam generator and the humidifier. It is a device that controls the amount of water. Any device can be used as long as the amount of water can be controlled. For example, a device that opens and closes the flow path of the water supply path 3 such as an electromagnetic valve may be used to flow water or stop water. Further, like the flow control valve, by changing the opening degree, the flow resistance of the water supply path 3 may be varied, and the amount of water flowing in the water supply path 3 may be adjusted. Further, the amount of water may be adjusted with a pump or the like.

  The controller 5 is a device that controls the water supplier 4 to replenish water supplied to at least one of the steam generator and the humidifier when the amount of recovered water from the exhaust gas in the fuel cell system decreases. is there. The controller 5 only needs to have a control function, and includes an arithmetic processing unit (not shown) and a storage unit (not shown) that stores a control program. Examples of the arithmetic processing unit include an MPU and a CPU. An example of the storage unit is a memory. The controller 5 may be composed of a single controller that performs centralized control, or may be composed of a plurality of controllers that perform distributed control in cooperation with each other.

[Operation]
Hereinafter, the operation of the fuel cell system will be described.

  In the operation of the fuel cell system of this embodiment, when the amount of recovered water from the exhaust gas in the fuel cell system decreases, the water supply device 4 is controlled to supply water supplied to at least one of the steam generator and the humidifier. Replenish. Except for the above points, the operation of the fuel cell system of the present embodiment is the same as that of the first embodiment, and its features will be described with reference to FIG.

  Exhaust gas in the fuel cell system includes off-fuel gas and off-oxidant gas that have not been used for power generation in the fuel cell 1, and combustion exhaust gas that burns off-fuel gas. When there is a possibility that the amount of water recovered from these exhaust gases is less than the amount of water necessary to establish water independence of the fuel cell system, the water supplier 4 is controlled so as not to include the off-gas of the fuel cell. Water recovered from the combustion exhaust gas of a combustion apparatus that burns using fuel is supplied to at least one of a steam generator and a humidifier. Thereby, even if the amount of water recovered from the exhaust gas decreases, water self-supporting of the fuel cell system can be established. In addition, supplying water to at least one of the steam generator and the humidifier through the water supply device 4 is limited to a case where water independence of the fuel cell system is severe. The supply through the supply path 3 is prevented. Here, it is common that sulfur is contained in the water recovered from the exhaust gas of the combustion apparatus that burns using the fuel that does not contain the off-gas of the fuel cell. The sulfur degrades the fuel cell 1 or a reformer that generates fuel gas that is a hydrogen-containing gas used in the fuel cell 1. Therefore, a sulfur removing device is required to remove it. The amount can be reduced as much as possible.

(Third embodiment)
A fuel cell system according to a third embodiment is the fuel cell system according to any one of the first embodiment and the second embodiment, and the fuel cell system includes a water tank that stores recovered water from exhaust gas in the fuel cell system. When the water level in the water tank decreases, the controller controls the water supply device to replenish the water tank with water supplied to at least one of the steam generator and the humidifier.

  With this configuration, the amount of remaining water in the fuel cell system can be managed by the water level of the water tank, and water can be supplied to the water tank by the water supply only when the water level of the water tank decreases. Become.

  The fuel cell system of the present embodiment may be configured in the same manner as the fuel cell system of the first embodiment and the second embodiment except for the above features.

[Device configuration]
FIG. 3 is a conceptual diagram showing an example of a schematic configuration of a fuel cell system according to the third embodiment.

  In the example shown in FIG. 3, the fuel cell system of the present embodiment includes a fuel cell 1, a water supply path 3, a water supply device 4, a controller 5, and a water tank 6.

  Since the fuel cell 1, the water supply path 3, the water supply device 4, and the controller 5 are the same as those in the first embodiment and the second embodiment, the description thereof is omitted.

  The water tank 6 is a tank that stores recovered water from exhaust gas in the fuel cell system. Any configuration can be used as long as it can store water. The water tank 6 includes a water level measuring means for measuring the water level, and can detect a drop in the water level when the water level falls below a predetermined level. The water level measuring means may be anything as long as it can detect a drop in water level. For example, there are a float switch, an ultrasonic type, a radio wave type, and a pressure type.

  The water supplied to the water tank 6 includes off-fuel gas and off-oxidant gas that have not been used for power generation in the fuel cell 1 and water recovered from combustion exhaust gas obtained by burning off-fuel gas, and a water supplier. There is water supplied from 4. Water stored from these paths is supplied to a steam generator or humidifier that uses water in the fuel cell system.

[Operation]
Hereinafter, the operation of the fuel cell system will be described.

  Since the operation of the fuel cell system of this embodiment is the same as that of the fuel cell system of either the first embodiment or the second embodiment, the features will be described with reference to FIG.

  The controller 5 measures whether or not the water level in the water tank 6 is lowered. When the water level is lowered, the controller 5 controls the water supply device 4 to use the fuel that does not contain the off-gas of the fuel cell 1. Water recovered from the combustion exhaust gas of the combustion apparatus that burns is supplied to the water tank 6. In addition, if the water level fall of the water tank 6 is eliminated, the controller 5 stops water supply to the water tank 6 by the water supply device 4. The stop of water supply may be performed at the same time when the lowering of the water level is eliminated, or may be after a predetermined time after the elimination of the lowering of the water level. The operation timing of the water supply device 4 should be designed according to the configuration of the water tank 6 and the water supply path 3, and any method may be used as long as the water tank 6 does not run out of water. .

  In addition, as a method of detecting the water level drop of the water tank 6, not only the method of directly detecting the water level of the water tank 6, but also the water level drop may be detected from the operating conditions. When the power generation output of the fuel cell 1 is relatively low with respect to the rated output for a predetermined time or longer, the water balance is considered to be severe as the fuel cell system, and water is supplied to the water tank 6 by the water supply device 4. It doesn't matter.

  In addition, since the water balance of a fuel cell system changes with electric power generation amounts, you may change the time which detects the deterioration of a water balance according to electric power generation amount. Any value may be used as long as the relationship between the power generation amount and the time is set according to the design of the fuel cell system.

(Fourth embodiment)
The fuel cell system according to the fourth embodiment is the fuel cell system according to any one of the first embodiment, the second embodiment, and the third embodiment, and the fuel cell system includes a condenser that condenses water in the exhaust gas. When the controller detects a decrease in the capacity of the condenser, the controller controls the water supply unit to replenish the water tank with water supplied to at least one of the steam generator and the humidifier.

  With this configuration, it is possible to supply water to the water tank with the water supply only when the capacity of the condenser is reduced.

  The fuel cell system of the present embodiment may be configured in the same manner as the fuel cell system of the first embodiment, the second embodiment, and the third embodiment except for the above features.

[Device configuration]
FIG. 4 is a conceptual diagram showing an example of a schematic configuration of a fuel cell system according to the fourth embodiment.

  In the example shown in FIG. 4, the fuel cell system of this embodiment includes a fuel cell 1, a condenser 2, a water supply path 3, a water supply device 4, a controller 5, and a water tank 6.

  Since the fuel cell 1, the water supply path 3, the water supply unit 4, the controller 5, and the water tank 6 are the same as those in the first embodiment, the second embodiment, and the third embodiment, the description thereof is omitted.

  The condenser 2 is an exhaust gas in the fuel cell system, which is off-fuel gas or off-oxidant gas that has not been used for power generation in the fuel cell 1, and water vapor contained in the combustion exhaust gas in which the off-fuel gas is burned. Is a device that collects water and collects water. In order to condense the water vapor, it is necessary to lower the temperature of the exhaust gas, and the refrigerant flows through the condenser 2 in order to lower the temperature. As the refrigerant, any medium that can be cooled by water, gas, or air can be used.

[Operation]
Hereinafter, the operation of the fuel cell system will be described.

  Since the operation of the fuel cell system of this embodiment is the same as that of the fuel cell system of any one of the first embodiment, the second embodiment, and the third embodiment, its features will be described with reference to FIG. To do.

  When detecting a decrease in the cooling capacity in the condenser 2, the controller 5 controls the water supplier 4 to supply water to the water tank 6. As a method for detecting a decrease in the cooling capacity of the condenser 2, it may be detected by a rise in exhaust gas temperature after passing through the condenser 2 or by a rise in the temperature of the refrigerant supplied to the condenser 2. I do not care. Moreover, you may detect by the temperature rise of the refrigerant | coolant which comes out of the condenser 2. FIG. Further, a predetermined temperature of the condenser 2 may be measured. Any detection method may be used as long as the capability reduction of the condenser 2 can be detected.

[First Modification]
FIG. 5 is a conceptual diagram illustrating an example of a schematic configuration of a fuel cell system according to a first modification of the fourth embodiment.

  As shown in FIG. 5, in this modification, a condenser for condensing water in the exhaust gas and a refrigerant temperature measuring instrument for measuring the temperature of the refrigerant supplied to the condenser are provided, and the controller is a refrigerant temperature measuring instrument. When the detected temperature of the refrigerant exceeds a predetermined temperature, the water supply unit is controlled to supply water supplied to at least one of the steam generator and the humidifier to the water tank.

In such a configuration, when the temperature rise of the refrigerant supplied to the condenser 2 is detected by the refrigerant temperature measuring device 7, water can be supplied to the water tank 6 by the water supply device 4.

  The fuel cell system according to this modification can be configured in the same manner as the fuel cell system according to any one of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment except for the points described above.

  The refrigerant temperature measuring device 7 is a temperature measuring device that measures the temperature of the refrigerant supplied to the condenser 2. As long as the refrigerant temperature can be measured, any device such as a thermocouple or a thermistor may be used.

  It is only necessary to supply water to the water tank 6 by the water supply device 4 because the temperature of the refrigerant supplied to the condenser 2 has become equal to or higher than the predetermined temperature, and the temperature of the refrigerant has risen above the predetermined temperature. It does not matter whether the cooling capacity in the condenser 2 is lowered or not.

  The predetermined temperature of the refrigerant that defines the timing of supplying water to the water tank 6 by the water supply device 4 is 50 ° C. in this modification. If the refrigerant temperature exceeds this temperature, the amount of water recovered in the condenser 2 may decrease, so that temperature was set. In addition, since the setting of the predetermined temperature differs depending on the device configuration of the fuel cell system, it may be set to an optimum temperature according to the configuration.

[Second Modification]
FIG. 6 is a conceptual diagram illustrating an example of a schematic configuration of a fuel cell system according to a second modification of the fourth embodiment.

  As shown in FIG. 6, in this modified example, a condenser for condensing water in the exhaust gas and an exhaust gas temperature measuring device for measuring the temperature of the exhaust gas flowing through the condenser are provided, and the controller is an exhaust gas temperature measuring device. When the detected temperature of the exhaust gas exceeds a predetermined temperature, the water supply unit is controlled to supply water supplied to at least one of the steam generator and the humidifier to the water tank.

  In such a configuration, when the temperature increase of the exhaust gas flowing through the condenser 2 is detected by the exhaust gas temperature measuring device 8, water can be supplied to the water tank 6 by the water supply device 4.

  The fuel cell system according to this modification can be configured in the same manner as the fuel cell system according to any one of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment except for the points described above.

  The exhaust gas temperature measuring device 8 is a device that measures the temperature of the exhaust gas after flowing through the condenser 2. As long as the exhaust gas temperature can be measured, any device such as a thermocouple or thermistor may be used.

  Water may be supplied to the water tank 6 by the water supply device 4 due to the temperature of the exhaust gas flowing through the condenser 2 being equal to or higher than the predetermined temperature. It does not matter whether the cooling capacity in the vessel 2 is lowered or not.

  The predetermined temperature of the exhaust gas that defines the timing of supplying water to the water tank 6 by the water supply device 4 is 55 ° C. in this modification. If the exhaust gas temperature exceeds this temperature, the amount of water recovered in the condenser 2 may be reduced, so that temperature was set. In addition, since the setting of the predetermined temperature differs depending on the device configuration of the fuel cell system, it may be set to an optimum temperature according to the configuration.

(Fifth embodiment)
A fuel cell system according to a fifth embodiment is the fuel cell system according to any one of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment, and the fuel cell system is an exhaust gas in the fuel cell system. It has a water tank to store recovered water from And the water supply channel
A first water supply path for supplying water recovered from combustion exhaust gas of a combustion apparatus that burns using fuel that does not include off-gas of a fuel cell to a water tank, a water tank, a water tank, a steam generator, and a humidifier; A second water supply path that connects at least one of the second water supply path, the first water supply path includes a first water purifier that removes sulfur compounds in the water, and a second water supply path Includes a second water purifier for removing ammonia in the water.

  With this configuration, the water supplied to the steam generator or the humidifier in the fuel cell system can be kept in high purity water, and deterioration of the fuel cell system can be prevented.

  The fuel cell system of the present embodiment may be configured in the same manner as the fuel cell system of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment except for the above features.

[Device configuration]
FIG. 7 is a conceptual diagram showing an example of a schematic configuration of a fuel cell system according to the fifth embodiment.

  In the example shown in FIG. 7, the fuel cell system of the present embodiment includes a fuel cell 1, a water supplier 4, a controller 5, a water tank 6, a first water supply path 9, and a second water A supply path 10, a first water purifier 11, and a second water purifier 12 are provided.

  Since the fuel cell 1, the water supplier 4, the controller 5, and the water tank 6 are the same as those of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment, the description thereof is omitted.

  The first water supply path 9 is a path for supplying water recovered from the combustion exhaust gas of the combustion apparatus that burns using the fuel that does not contain off-gas of the fuel cell 1 to the water tank 6. In a combustion apparatus that uses a fuel that does not contain off-gas of the fuel cell 1 to burn, it is common to burn city gas, LPG, or the like, which is a hydrocarbon-based gas supplied from infrastructure. These gases contain sulfur compounds, and the sulfur compounds are also contained in the water recovered from the combustion exhaust gas after combustion. Therefore, the sulfur compound is contained in the water flowing through the first water supply path 9.

  The second water supply path 10 is a flow path that connects the water tank 6 and at least one of the steam generator and the humidifier. Since water collected from the fuel cell system is collected in the water tank 6, it contains impurities. A particularly large impurity is ammonia derived from nitrogen gas contained in hydrocarbons such as city gas and LPG used to generate the hydrogen-containing gas.

  The first water purifier 11 is a water purifier for removing impurities in the water flowing through the first water supply path 9. Since the main component of impurities in the water flowing through the first water supply path 9 is a sulfur compound, a water purifier suitable for the purpose of removing it is used. In order to remove the sulfur compound, it is desirable to use an anion resin suitable for removing ionized sulfur or an activated carbon suitable for non-ionized sulfur. The situation of sulfur compounds varies depending on the combustion state and fuel composition of the combustion device that burns using fuel that does not contain off-gas of the fuel cell, so any water purifier can remove sulfur depending on the situation. It does not matter.

  The second water purifier 12 is a water purifier for removing impurities contained in the water in the water tank 6. Since the main component of the impurity is ammonia, a cationic resin suitable for removing it is used. The fuel cell system may contain impurities in addition to ammonia. In that case, activated carbon or anion resin may be used in combination with the cation resin in order to remove the impurities.

[Operation]
Hereinafter, the operation of the fuel cell system will be described.

  The operation of the fuel cell system of this embodiment is the same as that of the fuel cell system of any one of the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment. 7 for explanation.

  When water collected from the combustion exhaust gas of a combustion apparatus that burns using fuel that does not contain off-gas from the fuel cell 1 is supplied to the water tank 6, the water passes through the first water supply path 9 and is subjected to the first water purification. Is supplied to the vessel 11. In the first water purifier 11, sulfur compounds contained in the water are removed. The water from which the sulfur compound has been removed is carried by the water supply device 4 to the water tank 6 through the first water supply path 9. As a result, water from which the sulfur compound has been removed is supplied to the water tank 6. The positional relationship between the first water purifier 11 and the water supply device 4 may not be the order shown in FIG. 7, and the water that has passed through the water supply device 4 is supplied to the first water purifier 11. It doesn't matter.

  The water stored in the water tank 6 is converted to pure water by the second water purifier 12 and then supplied to at least one of a steam generator and a humidifier. This prevents water containing impurities from being supplied to the steam generator or humidifier, and prevents deterioration of the fuel cell system.

  By removing impurities originating from the combustion exhaust gas of the combustion device that burns using the fuel that does not contain the off-gas of the fuel cell 1 in the first water purifier 11, diffusion of impurities throughout the fuel cell system is prevented. It becomes possible. In addition, if the amount of water flowing through the first water purifier 11 is managed, even if the first water purifier 11 reaches the end of its performance, only the first water purifier 11 needs to be replaced. Since the influence on the second water purifier 12 can be avoided, the maintenance cost and the maintenance cycle can be optimized.

  In addition, when ammonia is also contained in the water collected from the combustion exhaust gas of the combustion apparatus that burns using the fuel that does not contain off-gas of the fuel cell 1, the first water purifier 11 is provided with a cationic resin that removes ammonia. You may include. In addition, when the content of ammonia in the water flowing through the first water purifier 11 is extremely small, the water purifier for removing ammonia may be only the second water purifier 12.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The fuel cell system of the present invention is useful as a fuel cell system equipped with water-utilizing equipment that improves the water self-supporting performance in the fuel cell system as compared with the prior art.

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Condenser 3 Water supply path 4 Water supply apparatus 5 Controller 6 Water tank 7 Refrigerant temperature measuring instrument 8 Exhaust gas temperature measuring instrument 9 1st water supply path 10 2nd water supply path 11 1st water purification 12 Second water purifier

Claims (8)

  Steam generation for generating water vapor used in the reforming reaction from water recovered from the combustion exhaust gas of a fuel cell that generates power using a hydrogen-containing gas and a combustion device that burns using fuel that does not contain off-gas of the fuel cell And a water supply path for supplying water to at least one of the humidifiers for humidifying the reaction gas supplied to the fuel cell.   The recovered water from the exhaust gas in the fuel cell system is configured to be supplied to at least one of the steam generator and the humidifier, and is supplied to at least one of the steam generator and the humidifier through the water supply path. A water supply for controlling the amount of flowing water, and when the amount of recovered water decreases, the water supply is controlled to replenish water supplied to at least one of the steam generator and the humidifier The fuel cell system according to claim 1, further comprising:   A water tank for storing recovered water from the exhaust gas in the fuel cell system, and the controller controls the water supplier when the water level of the water tank decreases, and at least the steam generator and the humidifier The fuel cell system according to claim 2, wherein water supplied to either one of the water tanks is replenished.   A condenser for condensing water in the exhaust gas, and when the controller detects a decrease in the capacity of the condenser, the controller controls the water supply unit to at least one of the steam generator and the humidifier; The fuel cell system according to claim 2, wherein water supplied to the water tank is replenished to the water tank.   A condenser for condensing the water in the exhaust gas; and a refrigerant temperature measuring device for measuring the temperature of the refrigerant supplied to the condenser, wherein the controller detects the temperature of the refrigerant detected by the refrigerant temperature measuring device. The fuel cell according to claim 2, wherein when the temperature exceeds a predetermined temperature, the water supply device is controlled to supply water supplied to at least one of the steam generator and the humidifier to the water tank. system.   A condenser for condensing water in the exhaust gas; and an exhaust gas temperature measuring device for measuring the temperature of the exhaust gas flowing through the condenser; 3. The fuel according to claim 2, wherein when the temperature exceeds a predetermined temperature, the water supply device is controlled to supply water supplied to at least one of the steam generator and the humidifier to the water tank. Battery system.   When the output of the fuel cell continues for a relatively low time, the controller controls the water supplier to supply water supplied to at least one of the steam generator and the humidifier. The fuel cell system according to claim 2, wherein the tank is replenished.   A water tank for storing recovered water from the exhaust gas in the fuel cell system, wherein the water supply path supplies water recovered from the combustion exhaust gas of a combustion device that burns using fuel that does not contain off-gas of the fuel cell; A first water supply path for supplying to the tank; the water tank; a second water supply path for connecting the water tank to at least one of the steam generator and the humidifier; The first water supply path includes a first water purifier that removes sulfur compounds in water, and the second water supply path includes a second water purifier that removes ammonia in water. Item 8. The fuel cell system according to any one of Items 1 to 7.

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