JP2006210151A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the total energy efficiency of the system by reducing humidifying energy of a gas supplied to a fuel cell. <P>SOLUTION: A first humidifying device is constituted by laminating a first flow passage plate 24 to form a flow passage of at least one supply gas of supply fuel gas and supply oxidizer gas with a second flow passage plate 25 to form at least one flow passage of exhausted fuel gas and exhausted oxidizer gas so that the flow passage of the supply fuel gas and the flow passage of the exhausted fuel gas will be contacted via a moisture moving membrane 23. A second humidifying device is constituted by laminating a second flow passage plate 25 to form a flow passage of at least one supply fuel gas with a first flow passage plate 24 to form a flow passage of a cooling water so that the flow passage of the supply gas and the flow passage of the cooling water will be contacted via a moisture moving membrane 23. The sum total lamination number of steps ratio of the first flow passage plate 24 and the second flow passage plate 25 in the second humidifying device against the humidifying device 50 is made 10-80%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that generates power and supplies heat using a fuel cell.

  Conventionally, in this type of fuel cell system, in a fuel cell, electric power and heat are generated by reacting a hydrogen-rich gas supplied as a fuel gas with air supplied as an oxidant gas. Are known. The fuel gas and the oxidant gas are supplied to the fuel cell after being humidified by the humidifying means. As a means for humidifying the fuel gas and the oxidant gas, for example, there is a bubbler that performs humidification through the fuel gas and the oxidant gas in warm water heated by a heater (see, for example, Patent Document 1).

On the other hand, moisture (water vapor) contained in the exhaust air (off gas) discharged from the air electrode side of the fuel cell is moved to the air supplied to the air electrode side of the fuel cell through the water vapor permeable membrane and supplied thereby A humidifying device that humidifies air is also known (see, for example, Patent Document 2). This humidifier can reduce energy required for humidification by performing humidification using high-temperature exhaust air.
JP 7-288134 A JP-A-6-132038

  However, in the conventional configuration, energy is consumed for heating the water in the bubbler, resulting in a decrease in energy efficiency of the fuel cell system.

  In addition, when humidification is performed using off-gas, the gas to be humidified (here, the supply air to be humidified) cannot be humidified to a dew point temperature equal to or higher than the humidification gas (here, the exhaust air from which moisture is supplied). Furthermore, in order to humidify the humidified gas to a high dew point temperature, a water vapor permeable membrane having a large membrane area is required, and there is a problem that the scale of the humidifying device becomes large.

  Therefore, it is difficult to make the conventional fuel cell system compact.

  In order to solve the above-described conventional problems, the present invention relates to a humidifier that humidifies at least one of a supply fuel gas and a supply oxidant gas that are a fuel gas and an oxidant gas supplied to a fuel cell, and A first flow path plate configured to form a flow path for at least one of the supply fuel gas and the supply oxidant gas; and the exhaust fuel. The supply gas flow path and the exhaust gas flow path are in contact with a second flow path plate forming a flow path for at least one of the gas and the exhaust oxidant gas through a moisture transfer film. The second humidifier is configured by stacking a plurality of layers, and the second humidifying device includes a second flow path plate that forms a flow path of at least one of the supply fuel gas and the supply oxidant gas, and the cooling water. Form the flow path A plurality of first flow path plates are stacked so that the flow path of the supply gas and the flow path of the cooling water are in contact with each other through the moisture transfer film, and the first humidification apparatus includes: The total number of stacked layers of the flow path plate and the second flow path plate is determined to be 10 to 80%.

  By ensuring the ratio of the number of stacked layers, it is possible to suppress a significant decrease in water temperature in the second humidifier.

  The fuel cell system of the present invention improves the energy efficiency of the entire system by reducing the energy required to humidify the gas supplied to the fuel cell, and also makes the system more compact, stabilizes the system operation, and reduces the cost. Can be planned.

  The invention according to claim 1 is a fuel cell that generates power using a fuel gas and an oxidant gas, and a supply fuel gas and a supply oxidant gas that are fuel gas and oxidant gas respectively supplied to the fuel cell. A humidifying device for humidifying at least one of the first humidifying device and the second humidifying device configured to sequentially humidify the first humidifying device and the first humidifying device respectively discharged from the fuel cell. The humidification is performed using moisture contained in at least one of the exhaust gas and the exhaust oxidant gas, which are the fuel gas and the oxidant gas, and the second humidifier is configured to use the humidified water. In the fuel cell system, the first humidifier is connected to a first flow path plate that forms a flow path for at least one of the supply fuel gas and the supply oxidant gas. And a second flow path plate that forms a flow path of at least one of the exhaust fuel gas and the exhaust oxidant gas, the supply gas flow path and the exhaust gas through a moisture transfer film. A plurality of stacked layers so as to be in contact with each other, and the second humidifier is configured to form a flow path for at least one of the supply fuel gas and the supply oxidant gas. A plurality of plates and a first flow path plate that forms the flow path of the cooling water are stacked so that the flow path of the supply gas and the flow path of the cooling water are in contact with each other through the moisture transfer film. The total stacking stage ratio of the first flow path plate and the second flow path plate in the second humidifier is 10 to 80%.

  With this configuration, the water temperature of the second humidifier is not significantly reduced, and therefore, energy consumed for maintaining the water temperature can be suppressed, and as a result, a highly efficient fuel cell cogeneration system can be provided. it can.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a configuration of a fuel cell cogeneration system (hereinafter simply referred to as a fuel cell system) according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the fuel cell system of the present embodiment includes an air supply device 40, a humidifying device 50 including a first humidifying device 22 and a second humidifying device 21a, a fuel cell 11, and a fuel supply. A device 41, a fuel processing device 42, a fuel processing humidifier 21b, a cooling water radiator 13, a cooling water tank 14, a cooling water pump 12, an air path 3, a first cooling water path 6, The second cooling water flow path 6a, the third cooling water flow path 6b, the hot water storage tank 45, and the hot water storage water circulation path 15 are configured as main elements.

  The air supplied from the air supply device 40 to the humidifier 50 via the air path 1 is humidified by the first humidifier 22 and further humidified by the second humidifier 21a. The air humidified by the second humidifier 21a is supplied to the air electrode side of the fuel cell 11 through the air path 3 as an oxidant gas.

  On the other hand, the fuel processing device 42 is supplied from the fuel supply device 41 via the fuel path 8 with a gas containing at least a compound composed of carbon and hydrogen, and a raw material such as alcohol. As the gas containing the compound composed of carbon and hydrogen and the alcohol, for example, city gas, propane, methane, natural gas and the like are preferable. Here, as the fuel processing device 42, specifically, a reforming unit that generates a reformed gas containing hydrogen by a reforming reaction, and a shift unit that reduces carbon monoxide in the reformed gas by a shift reaction, The case where the structure provided with the purification | cleaning part which further reduces carbon monoxide in the reformed gas which passed through this metamorphic part by selective oxidation reaction is demonstrated.

  In the fuel processing device 42, a hydrogen-rich gas is generated by heating the supplied raw material in an atmosphere containing water vapor. The hydrogen-rich gas is supplied to the fuel processing humidifier 21b via the fuel gas path 9a and humidified. Here, as the fuel processing humidifier 21b, the humidifier described above in the second humidifier 21a is used.

  The humidified hydrogen-rich gas is supplied as a fuel gas of the fuel cell 11 to the fuel electrode side of the fuel cell 11 through the fuel gas path 9b. In the fuel cell 11, electricity is generated by the reaction between the air supplied to the air electrode side and the hydrogen-rich gas (hereinafter referred to as fuel gas) supplied to the fuel electrode side, generating electricity and heat. To do.

  Of the air supplied to the fuel cell 11, the air that has not been used for the reaction is supplied to the first humidifier 22 via the exhaust air path 4. In the first humidifier, the moisture supplied to the fuel cell 11 as an oxidant gas is humidified using moisture contained in the supplied exhaust air. Then, the air that has passed through the first humidifier 22 is exhausted through the exhaust gas path 5. On the other hand, the fuel gas that has not been used for the reaction in the fuel cell 11 is discharged through the exhaust gas path 10.

  The second cooling device 21a is connected to the first cooling water flow path 6a recovered from the fuel cell 11, passes through the air path 1, and the air humidified by the first humidifying device 22 is supplied to the second humidifying device 21a. The cooling water further humidified in step 2 is connected to the second cooling water flow path 6b.

  The hot water storage tank 45 and the hot water storage pump 44 for supplying the water stored in the hot water storage tank 45 and the water supplied from the previous hot water storage tank 45 to the hot water storage tank 45 again via the cooling water radiator (heat exchanger) 13. Heat is supplied to the cooling water radiator 13 from the cooling water that has been used for humidification by the second humidifying device 21 a by the returning hot water circulation path 15, and this heat passes through the hot water circulation path 15 to store the hot water tank. 45, where heat is stored.

  Further, in order to remove the heat generated in the fuel cell 11, the cooling water in the cooling water tank 14 is pressurized by the cooling water pump 12 and supplied to the fuel cell 11 through the cooling water path 7. Here, the cooling water in the cooling water tank 14 is maintained at about 70 ° C. The heat of the fuel cell 11 is removed by the supplied cooling water. Then, the cooling water whose temperature has been recovered by recovering the heat passes through the first cooling water flow path 6a, the second cooling water flow path 6b, and the third cooling water flow path 6c in order, and again becomes the cooling water. Returned to tank 14. Here, a cooling water radiator 13 is provided between the second cooling water channel 6 b and the third cooling water channel 6 c, and heat of the cooling water is released by the cooling water radiator 13.

  By such heat radiation, the cooling water is cooled again to about 70 ° C. In the fuel cell system, the cooling water is circulated in this way, and the temperature of the cooling water is stably maintained at a predetermined temperature, so that the fuel cell 11 is maintained at a predetermined temperature. It becomes possible to do.

  Next, the humidification operation to the supply air in the 1st humidification apparatus of the humidification apparatus 50 which is the characteristics of this Embodiment is demonstrated.

  2, 3, 4, and 5 are diagrams for explaining the configuration of the first humidifier in the fuel cell system of FIG. 1, and FIG. 2 schematically illustrates the configuration of the first flow path plate. FIG. 3 is a perspective view schematically showing the configuration of the second flow path plate, and FIG. 4 is a diagram in which the first flow path plate of FIG. 2 and the second flow path plate of FIG. It is a typical perspective view of the comprised humidifier. FIG. 5 is a longitudinal sectional view showing the configuration of the humidifier.

  As shown in FIGS. 2, 3, 4, and 5, the first humidifier 22 is interposed between the first end plate 31 and the second end plate 32. A plurality of flow path plates 24 and second flow path plates 25 are alternately stacked via a moisture transfer film 23. The first flow path plate 24 and the second flow path plate 25 have outer peripheral seal portions 24 s and 25 s, respectively, and seal leakage of supply air and discharge air from the first humidifier 22 to the outside. . In the first flow path plate 24, a flow path (hereinafter referred to as a supply air flow path) 24 a of air supplied from the fuel cell 11 is formed in a hollow portion (through space) through which the first flow path plate 24 penetrates. In the formed second flow path plate 25, a flow path (hereinafter referred to as “discharge air flow path”) 25 a of air discharged from the fuel cell 11 has a hollow portion (penetrated through the second flow path plate 25). Space). The moisture transfer membrane 23 is a membrane that selectively permeates moisture. For example, a proton conductive polymer electrolyte membrane such as a Nafion-based membrane is used. The supply air flow path 24a of the first flow path plate 24 is formed by a hollow hole penetrating through the central portion of the first flow path plate 24, and the manifold hole 28a serving as an integrally formed supply air path, It communicates with 28b.

  Similarly, with respect to the second flow path plate 25, the exhaust air flow path 25a is formed by a hollow hole penetrating the central portion of the second flow path plate 25, and the exhaust air path formed integrally therewith. It communicates with the manifold holes 29a and 29b. Then, the plurality of first flow path plates 24 and the second flow paths are arranged so that the positions of the manifold holes 28a, 28b, 29a, and 29b of the first flow path plate 24 and the second flow path plate 25 coincide with each other. By alternately laminating the path plates 25, in the laminated body, the supply air introduction flow path 28a ′ in which the manifold holes 28a communicate with each other, the supply air take-out flow path 28b ′ in which the manifold holes 28b communicate with each other, An exhaust air introduction passage 29a ′ in which the manifold hole 29a communicates and an exhaust air extraction passage 29b ′ in which the manifold hole 29b communicates are formed. The supply air introduction flow path 28 a ′ in which the manifold hole 28 a communicates is connected to the air path 1, and the supply air take-out flow path 28 b ′ in communication with the manifold hole 28 b is connected to the second end plate 32. It is connected to the manifold hole 30.

  Thereby, the air (that is, supply air) supplied from the air path 1 to the first flow path plate 24 of the first humidifier 22 is formed in the hollow hole (through space) of the first flow path plate 24. It flows along the supply air flow path 24 a and is sent to the manifold hole 30 of the second end plate 32. On the other hand, an exhaust air introduction passage 29 a ′ in which the manifold hole 29 a communicates is connected to the air path 4, and an exhaust air extraction passage 29 b ′ in which the manifold hole 29 b communicates is connected to the air path 5. Has been. As a result, the air (that is, the exhaust air) supplied from the air path 4 to the second flow path plate 25 of the first humidifier 22 passes through the exhaust air introduction flow path 29a ′, and the second end plate 32. In this case, the air flows along the exhaust air flow path 25 a formed in the hollow hole (through space) of the plate 25, forms a substantially U-shaped flow path, and is sent to the air path 5.

  In this way, in the hollow hole (through space) of the second flow path plate 25, a flow of supply air and discharge air that are opposed to each other through the moisture transfer film 23 is formed.

  In the first humidifier 22, the plurality of first flow path plates 24 and second flow path plates 25 having the above-described configuration are stacked via the moisture transfer film 23. The supply air flowing through the supply air flow path 24 a of the flow path plate 24 and the exhaust air flowing through the discharge air flow path 25 a of the second flow path plate 25 are in contact with each other via the moisture transfer film 23.

  Here, since the exhaust air discharged from the fuel cell 11 contains more moisture than the supply air, in the first humidifier 22 having such a configuration, the supply air is supplied from the exhaust air via the moisture transfer film 23. Moisture (specifically, water vapor) is given to. In particular, the supply air and the discharge air form opposing flows and come into contact with each other via the moisture transfer film 23, so that the moisture is efficiently moved. Further, since the temperature of the exhaust air discharged from the fuel cell 11 is higher than that of the supply air, in the first humidifier 22, thermal energy is given from the exhaust air to the supply air as the moisture moves, thereby Supply air is heated.

  The supply air humidified by the first humidifier 22 as described above is supplied to the second humidifier 21a via the second end plate 32. Here, since the air supplied to the second humidifier 21a has been heated and humidified in advance by the first humidifier 22 as described above, it is humidified only by the second humidifier 21a as in the prior art. Compared with the case where it does, less heat and humidification may be sufficient in the 2nd humidification apparatus 21a. Therefore, it is possible to reduce the heat energy and moisture required for the second humidifier 21a.

  Furthermore, in the predetermined size of the humidifier 50, the second humidifier configuration ratio with respect to the humidifier 50 is within a range of 10 to 80% as shown in the characteristic diagram of FIG. A predetermined dew point and temperature can be secured for the dew point at the outlet (air flow path 3) and the temperature of the second cooling water flow path 6b.

  Thus, in this Embodiment, it is possible to reduce the energy consumption in 21a in a 2nd humidifier by heating and humidifying supply air by the 1st humidifier 22 beforehand, It becomes possible to improve the energy efficiency of the entire system. Moreover, since the water consumption in the 2nd humidification apparatus 21a can be reduced, it becomes possible to suppress the quantity of the water | moisture content supplied to the 2nd humidification apparatus 21a. As a result, it is possible to suppress temperature fluctuations due to the replenished moisture, and a stable humidification amount can be realized in the second humidifier 21a.

  Furthermore, in the fuel cell system having such a configuration, the first humidifier 22 and the second humidifier 21a can efficiently perform humidification step by step, so that the supply air is humidified to a high dew point. However, the large first humidifier and the second humidifier are not required, and thus the system can be made compact.

  In the above description, the case where the fuel gas supplied to the fuel cell 11 (hereinafter referred to as supply fuel gas) is humidified only by the fuel humidifier 21b has been described. Similarly to the case of air, the first fuel humidifier may be provided upstream of the second fuel humidifier 21a to perform humidification step by step.

  In such a configuration, the exhaust fuel gas discharged from the fuel cell 11 is supplied to the first fuel humidifier, and in the first fuel humidifier, the moisture of the exhaust fuel gas is given to the supply fuel gas, and the supply fuel gas While the humidification is performed, the heat energy of the exhaust fuel gas is given to the supply fuel gas to heat the supply fuel gas. Thereby, as described above in the case of supply air, the energy consumption in the second fuel humidifier 21b is reduced, and as a result, the energy efficiency of the fuel cell system is improved and the second fuel is increased. The moisture consumption in the humidifying device 21b is reduced, and the humidification amount can be stabilized.

  Such a first fuel humidifier is, for example, similar to the configuration of the first humidifier 22 described above on the air supply side, with a plurality of first flow path plates and second flow path plates via a moisture transfer film. In this case, the supply fuel gas flow path 24a is formed in the hollow hole of the first flow path plate, and the exhaust fuel gas flow path is formed in the hollow hole of the second flow path plate. 25a is formed.

  Thus, in the fuel cell system, the first humidifier that humidifies the supply gas using the exhaust gas from the fuel cell 11 may be provided on both the air side and the fuel side. It may be used for one side. Note that the exhaust air from the fuel cell 11 has a higher humidity than the exhaust fuel gas, and the exhaust air is more efficient in transferring moisture through the moisture transfer film than the exhaust fuel gas. It is possible to feed the supply air. For this reason, it is preferable to arrange the first humidifier on the air supply side.

  As described above, the fuel cell system according to the present invention improves the energy efficiency of the entire system by reducing the energy required for humidifying the gas supplied to the fuel cell, and also makes the system more compact and stabilizes the system operation. Since it is possible to reduce the cost, it can be applied to uses such as dehumidification of supply air by utilizing the dehumidification of the exhaust air path 4 of the first humidifier.

Schematic diagram showing the configuration of the fuel cell system according to Embodiment 1 of the present invention. The perspective view which shows typically the structure of the 1st flow-path plate which comprises the humidification apparatus in the embodiment. The perspective view which shows typically the structure of the 2nd flow-path plate which comprises the humidification apparatus in the embodiment. Schematic perspective view of a humidifier configured by laminating a first flow path plate and a second flow path plate in the same embodiment The longitudinal cross-sectional view which shows the structure of the humidification apparatus in the same embodiment Characteristic diagram of second humidifier composition ratio in the same embodiment

Explanation of symbols

1, 2, 3 Air path 4, 5 Exhaust air path 6a 1st cooling water flow path 6b 2nd cooling water flow path 6c 3rd cooling water flow path 7 Cooling water flow path 11 Fuel cell 12 Cooling water pump 13 Cooling water radiator DESCRIPTION OF SYMBOLS 14 Cooling water tank 15 Hot water storage path 21a 2nd humidification apparatus 22 1st humidification apparatus 23 Moisture transfer film 24 1st flow path plate 24a Supply air flow path 24s, 25s Peripheral seal part 25 2nd flow path plate 25a Exhaust air flow path 31 First end plate 32 Second end plate 33 Third end plate 50 Humidifier

Claims (1)

  A fuel cell that generates power using a fuel gas and an oxidant gas, and a humidifier that humidifies at least one of a supply gas and a supply oxidant gas that are fuel gas and oxidant gas supplied to the fuel cell, respectively. And the humidifier is composed of a first humidifier and a second humidifier that sequentially humidify, and the first humidifier is composed of the fuel gas and the oxidant gas discharged from the fuel cell, respectively. In the fuel cell system, wherein the humidification is performed using moisture contained in at least one of the exhaust fuel gas and the exhaust oxidant gas, and the second humidifier is configured to perform the humidification using hot water. The first humidifying device includes a first flow path plate that forms a flow path of at least one of the supply fuel gas and the supply oxidant gas, and the exhaust fuel gas. And the second flow path plate that forms the flow path of at least one of the exhaust oxidant gas so that the flow path of the supply gas and the flow path of the exhaust gas are in contact with each other through the moisture transfer film. A plurality of layers, and the second humidifier comprises a second flow path plate that forms a flow path of at least one of the supply fuel gas and the supply oxidant gas, and the cooling water. A plurality of first flow path plates that form flow paths are stacked so that the flow path of the supply gas and the flow path of the cooling water are in contact with each other through the moisture transfer film, and the second flow path plate A fuel cell system in which a total stacking stage ratio of the first flow path plate and the second flow path plate in the humidifier is 10 to 80%.

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