JP5266635B2 - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system in which energy efficiency of the entire system is improved by reducing energy required for humidifying gas supplied to a fuel cell, and in which compactification of a system, stabilization of system operation, and cost reduction are achieved. <P>SOLUTION: In the fuel cell system, cooling water flowing through a cooling water passage 7 humidifies a supplied oxidizing gas in an oxidizing gas humidifiers 21, 22 after humidifying a supplied fuel gas in a fuel gas humidifier 20, and thereafter flows outside form the humidifier through the cooling water passage contacting with the fuel gas humidifier 20, while an exhaust fuel gas passage is installed so that an exhaust fuel gas exhausted from the fuel gas humidifies the supplied fuel gas in the fuel gas humidifier 20 after passing through the vicinity of the oxidizing gas humidifiers 21, 22, and then flows outside from the humidifier. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

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

  A fuel cell system is known to generate electric power and heat in a fuel cell by reacting a hydrogen-rich gas supplied as a fuel gas with air supplied as an oxidant gas.

  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 humidifier that humidifies air is known (for example, see Patent Document 2).

This humidifier is intended to reduce energy required for humidification by performing humidification using high-temperature exhaust air.
JP 7-288134 A JP-A-6-132038

  However, the humidifying means described in Patent Document 1 consumes energy to heat water in the bubbler, and thus causes a reduction in energy efficiency of the fuel cell system.

  Further, the humidifier described in Patent Document 2 can humidify a humidified gas (here, supply air to be humidified) to a dew point temperature equal to or higher than the humidification gas (exhaust air from which moisture is supplied here). In addition, 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 the scale of the humidifying device is increased.

  Therefore, it is difficult to make the fuel cell system compact with this humidifier.

  The present invention solves the above-described problems of the conventional fuel cell system. By reducing the energy required for humidifying the gas supplied to the fuel cell, the energy efficiency of the entire system is improved and the system is made compact. An object of the present invention is to provide a fuel cell system that can stabilize system operation, reduce costs, and improve quality during manufacture.

In order to solve the above problems, the present invention provides a fuel cell that generates power using a fuel gas and an oxidant gas, a fuel gas humidifier that humidifies a supply fuel gas supplied to the fuel cell, and the fuel cell. containing gas humidifier to humidify the supply oxidizing gas supplied, a fuel cell system which have a cooling water passage through which cooling water flows for cooling the heat generated during power generation of the fuel cell, the cooling water flowing through the cooling water path, after heating the supply fuel gas in the fuel gas humidifier, while humidifying the supply oxidant gas in the oxidant gas humidifier, which is discharged from the fuel cell A fuel cell system configured to provide an exhaust fuel gas path so that exhaust fuel gas passes through a through-hole penetrating the inside of the oxidant gas humidifier, is then humidified by the fuel gas humidifier, and flows out of the humidifier; did Than is.

  Therefore, the exhaust fuel gas path is provided so as to pass through the vicinity of the oxidant gas humidifier before being humidified by the fuel gas humidifier. As a result, the temperature before humidification of the exhaust fuel gas is set at the outlet of the fuel cell. Therefore, the temperature of the oxidant gas humidifier can be reduced, and a certain amount of water is recovered, so that a highly efficient system can be provided.

  The fuel cell system of the present invention improves energy efficiency and is excellent in durability and can realize stable operation of the fuel cell system. In addition, the fuel cell system can be made compact and simplified, and the cost can be reduced, the number of man-hours during manufacturing, and the quality can be improved.

According to a first aspect of the present invention, there is provided a fuel cell that generates power using a fuel gas and an oxidant gas, a fuel gas humidifier that humidifies a supply fuel gas supplied to the fuel cell, and a supply oxidation supplied to the fuel cell. agent and the oxidizing gas humidifier for humidifying gas, a the fuel cell fuel cell system which have a cooling water passage through which cooling water for cooling the heat generated during power generation flows of flowing through the cooling water passage cooling water, after heating the supply fuel gas in the fuel gas humidifier, while humidifying the supply oxidant gas in the oxidant gas humidifier, exhaust fuel gas discharged from the fuel cell the oxidation The fuel cell system is configured by providing an exhaust fuel gas path so as to pass through a through-hole penetrating the inside of the agent gas humidifier, and then humidify by the fuel gas humidifier and flow out of the humidifier.

  By adopting such a configuration, the exhaust fuel gas path is provided in the vicinity of at least one of the first oxidant gas humidifier and the second oxidant gas humidifier before being humidified by the fuel gas humidifier. As a result, the temperature before the humidification of the exhaust fuel gas is lower than the temperature at the outlet of the fuel cell and can be suppressed to the temperature of the oxidant gas humidifier, and a certain amount of water is recovered. Can provide a highly efficient system.

In a second aspect based on the first aspect, the oxidant gas humidifier comprises a first oxidant gas humidifier and a second oxidant gas humidifier, and the second oxidant gas humidifier comprises: The exhaust gas is disposed between the fuel gas humidifier and the first oxidant gas humidifier, and in the exhaust fuel gas path, the exhaust fuel gas is the first oxidant gas humidifier and the second oxidant. A fuel cell system is configured in which an exhaust fuel gas path is configured to pass through the through hole provided in at least one of the gas humidifiers, and then humidify by the fuel gas humidifier and flow out of the humidifier.

  With this configuration, the exhaust fuel gas path is routed to at least one of the casing of the first oxidant gas humidifier and the first flow path plate of the second oxidant gas humidifier. Since the through hole is provided, the exhaust fuel gas temperature can be controlled more systematically, the energy efficiency of the entire system can be improved, and the oxidizer / fuel gas humidifier can be made more compact.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

(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 according to Embodiment 1 includes an air supply device 40, an oxidant gas humidifier provided with a first oxidant gas humidifier 22 and a second oxidant gas humidifier 21. The device 50, the fuel cell 11, the fuel supply device 41, the fuel processing device 42, the fuel gas humidifier 20, the cooling water radiator 13, the cooling water tank 14, the cooling water pump 12, and the first The air path 1, the second air path 2, the third air path 3, the first cooling water path 6a, the second cooling water path 6b, the third cooling water path 6c, and the fourth The cooling water path 6d, the hot water storage tank 45, and the hot water storage water circulation path 15 are the main elements.

  In particular, the fuel gas humidifier 20 and the oxidant gas humidifier 50 constitute an integrated humidifier 51, the details of which will be described later.

  Next, the operation of the entire system will be described.

  The air supplied from the air supply device 40 to the oxidant gas humidifier 50 through the first air path 1 is humidified by the first oxidant gas humidifier 22 and then passes through the second air path 2. Further, the second oxidant gas humidifier 21 is further humidified. The air humidified by the second humidifier 21 is supplied to the air electrode side of the fuel cell 11 through the third air path 3 as an oxidant gas.

  On the other hand, the raw material is supplied from the fuel supply device 41 to the fuel processing device 42 via the first fuel gas path 8. The raw material is preferably a gas containing at least a compound composed of carbon and hydrogen (for example, city gas, propane, methane, natural gas, etc.), alcohol, or the like.

  Here, the fuel processing device 42 specifically includes 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, A purification unit (none of which is shown) for further reducing carbon monoxide in the reformed gas that has passed through the transformation unit by a selective oxidation reaction is provided, and since such a configuration is well known, description thereof is omitted.

  And in the fuel processing apparatus 42, hydrogen-rich gas is produced | generated by heating the supplied raw material in the atmosphere containing water vapor | steam. The hydrogen-rich gas is supplied to the fuel gas humidifier 20 via the second fuel gas path 9a and is humidified.

  The humidified hydrogen-rich gas is supplied as the fuel gas of the fuel cell 11 to the fuel electrode side of the fuel cell 11 through the third fuel gas path 9b. In the fuel cell 11, electricity is generated by the reaction between air supplied to the air electrode side and hydrogen-rich gas (hereinafter referred to as fuel gas) supplied to the fuel electrode side, and electricity and heat are generated. Occur. The details of this reaction are well known and will not be described.

  Of the air supplied from the third air path 3 to the fuel cell 11, the air that has not been used for the reaction becomes exhausted air, and the first oxidant gas is humidified via the first exhaust oxidant gas path 4. To the container 22.

  Humidification of the air (oxidant gas) flowing into the first oxidant gas humidifier 22 from the first air path 1 described above is performed using moisture contained in the exhaust air. Since the heat of the exhaust air is also used, a wet heat exchange action is performed in the first oxidant gas humidifier 22.

  Then, the exhaust air that has passed through the first oxidant gas humidifier 22 is discharged through the second exhaust oxidant gas path 5.

  The fuel gas that has not been used for the reaction in the fuel cell 11 becomes exhausted fuel gas, is supplied to the fuel gas humidifier 20 through the fourth fuel gas path 10, and is discharged through the fuel gas discharge path 10a.

  Humidification of the hydrogen-rich gas generated by the fuel processing device 42 is performed using the moisture of the exhaust gas that has flowed into the second oxidant gas humidifier 21 via the fourth fuel gas path 10. Strictly speaking, since the heat of the exhausted fuel gas is also used, a wet heat exchange action is performed in the fuel gas humidifier 20.

  Further, the cooling water whose heat has been recovered by the fuel cell 11 flows into the fuel gas humidifier 20 via the first cooling water path 6a, and then the second oxidant gas humidification from the second cooling water path 6b. It flows into the vessel 21 and is supplied to the cooling water radiator 13 via the third cooling water path 6c, where heat is recovered.

  That is, the cooling water heats the condensed water of the exhaust gas supplied to the fuel gas humidifier 20 via the fourth fuel gas path 10 and then flows to the second humidifier 21 where fuel is supplied. The air (oxidant gas) supplied to the battery 11 is humidified. The humidification performed by the second humidifier 21 also has a heat exchange function because the temperature of the cooling water is used in addition to the water of the cooling water.

  In other words, the humidification (wet heat exchange action) of the air supplied from the air supply device 40 is performed by the moisture and heat of the exhaust gas flowing in from the first exhaust oxidant gas path 4 in the first oxidant gas humidifier 22. The second oxidant gas humidifier 21 is used by utilizing the water and heat of the cooling water.

  Further, the hot water tank 45, the hot water pump 44 for supplying the water stored in the hot water tank 45, and the water supplied from the hot water tank 45 are passed through the cooling water radiator (heat exchanger) 13. In the hot water circulation path 15 that returns to the hot water storage tank 45 again, the cooling water radiator 13 is given the heat of the cooling water after being used for humidification by the second oxidant humidifier 21 as described above. The hot water is supplied and stored in the hot water tank 45 through the hot water circulation path 15.

  Further, the cooling water that has passed through the cooling water radiator 13 flows to the cooling water tank 14 via the fourth cooling water path 6d. Then, the cooling water in the cooling water tank 14 is circulated by being pressurized by the cooling water pump 12 to be removed from the fuel cell 11 and supplied to the fuel cell 11 again through the cooling water path 7. repeat.

  Here, the cooling water in the cooling water tank 14 is maintained at about 70 ° C., and this temperature is a temperature at which sufficient heat exchange with the fuel cell 11 is possible.

  Further, the cooling water will be described in detail. The cooling water whose temperature is about 75 ° C. by recovering the heat of the fuel cell 11 is the first cooling water path 6a, the second cooling water path 6b, the third cooling water. It is returned to the cooling water tank 14 again via the cooling water path 6c and the fourth cooling water path 6d.

  Here, a cooling water radiator 13 is provided between the third cooling water path 6 c and the fourth cooling water path 6 d, and the 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 according to the first embodiment, the cooling water is circulated as described above, and the temperature of the cooling water is stably maintained at a predetermined temperature. Can be maintained at a predetermined temperature.

  Further, in the first embodiment, the fuel gas humidifier 20 and the oxidant gas humidifier 50 are integrated to form a humidifier 51. Next, the fuel that is a feature of the first embodiment is shown in FIG. The gas humidifier 20 and the oxidant gas / fuel gas humidifier 51 will be described.

  2, 3, and 4 are explanatory diagrams for explaining the configuration of the oxidizer / fuel gas humidifier in the fuel cell system shown in FIG. 1 and the wet heat exchange action.

  2, 3, and 4, the oxidant gas / fuel gas humidifier 51 is sandwiched between the first end plate 61 and the second end plate 62, and the first oxidant gas humidifier 22 is the first end plate 61. Between the opposite surface of the first oxidant gas humidifier 22 and the second oxidant gas humidifier 21, an oxidant gas end plate 63 is in contact with the second end plate 61. An intermediate end plate 64 is interposed between the opposite surface of the oxidant gas humidifier 21 and the fuel gas humidifier 20. The first oxidant gas humidifier has a hollow fiber membrane configuration.

  The first end plate 61 has a supply oxidant gas inlet 65, an exhaust oxidant gas inlet 66, an exhaust oxidant gas outlet 67, and an exhaust fuel gas inlet 68, and the second end plate 62. Has a supply oxidant gas outlet 69, a supply fuel gas outlet 70, a supply fuel gas inlet 71, an exhaust fuel gas outlet 72, a cooling water inlet 73, and a cooling water outlet 74. The agent gas humidifier 22 includes a first humidification module 75, a casing 76 that leads piping (not shown) to the first humidification module 75, and a through hole 102 that allows exhaust fuel gas to pass through the casing 76. .

  The second oxidant gas humidifier 21 is configured by laminating a first flow path plate 77 and a moisture transfer film 23, and the first flow path plate 77 has a supply oxidant gas flow path 78 on one side, A first cooling water flow path 79 is formed on the other surface, and a supply oxidant gas inlet manifold 80, a supply oxidant gas outlet manifold 81, a first cooling water inlet manifold 82, and a first cooling water outlet manifold. 83 and an exhaust fuel gas through hole 84.

  In addition, the fuel gas humidifier 20 includes a second flow path plate 85, a third flow path plate 86, and a second flow path plate 85, the exhaust fuel gas flow path 87 on one side, and the second flow path plate 85 on the other side. A cooling water passage 88 is formed, a supply fuel gas passage 89 is formed on one side of the third passage plate 86, an exhaust fuel gas passage 87 and a third passage plate 86 of the second passage plate 85. The water transfer film 23 is disposed between the supply fuel gas flow paths 89, and the second flow path plate 85 includes a second cooling water inlet manifold 90, a second cooling water outlet manifold 91, and the like. , An exhaust fuel gas inlet manifold 92, an exhaust fuel gas outlet manifold 93, a supply oxidant gas through hole 94, supply fuel gas through holes 95a and 95b, and a coolant recovery hole 101, and a third flow path The plate 86 has a supply fuel gas inlet port. Hold 96, supply fuel gas outlet manifold 97, second cooling water inlet hole 98, second cooling water outlet hole 99, exhaust fuel gas through hole 100, oxidant gas through hole 94, and cooling water recovery The hole 101 is configured. The fuel gas humidifier 20 and the second oxidant gas humidifier 21 are internally separated by a moisture transfer film (water vapor permeable film) 23, and the moisture transfer film 23 moves from the high moisture concentration side to the low moisture concentration side. It is made of a material that can move moisture (water vapor) and can move heat from the high temperature side to the low temperature side.

  Here, as the moisture transfer membrane 23, for example, a proton conductive polymer electrolyte membrane represented by a Nafion-based membrane or the like is used.

  Further, the fuel gas humidifier 20, the first oxidant gas humidifier 22, and the second oxidant gas humidifier 21 are configured such that their outer shells are in contact with each other, as shown in FIG. Both ends thereof are fixed to the pair of end plates 61 and 62 by appropriate means, and are unitized so that a single humidifier 51 is obtained.

  The exhaust fuel gas flows through the humidifiers 20, 21, and 22 of the humidifier 51 having the above-described configuration as follows.

  The fuel gas flows into the supply fuel gas flow path 89 of the fuel gas humidifier 20, flows into the fuel electrode side of the fuel cell 11 from the third fuel gas path 9b, and reacts with the oxidant gas. Condensed water is also generated along with this reaction, and the fuel gas remaining without reacting with the oxidant gas flows again into the oxidizer / fuel gas humidifier 51 from the fourth fuel gas path 10 together with the condensed water, The amount of water necessary for humidifying the fuel gas is temporarily collected and stored in the exhaust fuel gas passage 87 of the third passage plate 85. The fuel gas in the exhaust fuel gas flow path 87 is discharged through the fuel gas discharge path 10a.

  The moisture (water vapor) of the condensed water in the exhaust fuel gas flow path 87 permeates into the fuel gas chamber 89 by the action of allowing the moisture of the moisture transfer film (water vapor permeable film) 23 to permeate.

  The exhaust fuel gas passage 87 is provided with a second cooling water passage 88 through a second passage plate 85 made of a material having good thermal conductivity. The cooling water flowing through the second cooling water channel 88 is heated to about 75 ° C. when leaving the fuel cell 11, but stays in the exhaust fuel gas channel 87 and the temperature drops to about 50 ° C. . However, since the cooling water temperature in the second cooling water flow path 88 is constantly maintained at about 75 ° C., the temperature when leaving the fuel cell 11, the condensed water in the exhaust fuel gas flow path 87 is heated to a constant temperature. ing.

  Therefore, the condensed moisture (water vapor) that has passed through the supply fuel gas channel 89 is also at a predetermined temperature, and the condensed moisture exchanges wet heat with the fuel gas flowing through the supply fuel gas channel 89 to humidify the fuel gas.

  Further, the exhausted fuel gas passes through the through hole 102 provided in the casing of the first oxidant gas humidifier 22 from the fourth fuel gas path 10 and flows into the second oxidant gas humidifier 21. In the second oxidant gas humidifier, the exhaust fuel gas passes through the exhaust gas through hole 84 provided in the oxidant gas end plate 63, the moisture transfer film 23, and the first flow path plate 77. The first oxidant gas humidifier 22 and the second oxidant gas humidifier 21 maintain the temperature and dew point of the supplied oxidant gas at predetermined values lower than the exhaust fuel gas temperature, and the oxidant The main body of the gas humidifier 50 also maintains a constant temperature lower than the exhaust fuel gas temperature. Therefore, since the exhaust fuel gas that has passed through the oxidant gas humidifier 50 flows into the fuel gas humidifier after a certain temperature lowers than the temperature immediately after leaving the fuel cell, the fuel gas humidifier A certain amount of water to be humidified by the vessel can be secured.

  As described above, in the first embodiment, the exhaust fuel gas path is connected to at least the first oxidant gas humidifier and the second oxidant gas humidifier before being humidified by the fuel gas humidifier. As a result of passing through one vicinity, the temperature before humidification of the exhausted fuel gas can be suppressed to a temperature lower than the temperature at the outlet of the fuel cell and to the temperature of the oxidant gas humidifier, and a certain amount of water Therefore, a highly efficient system can be provided.

  Further, since the exhaust fuel gas path is provided in at least one of the casing of the first oxidant gas humidifier and the first flow path plate of the second oxidant gas humidifier, the exhaust fuel gas through hole is provided. The exhaust gas temperature can be controlled more systematically, the energy efficiency of the entire system can be improved, and the oxidizer / fuel gas humidifier can be made more compact.

  In the first embodiment, the first oxidant gas humidifier 22 has a hollow fiber membrane humidifier configuration. However, a humidifier configuration using a flat membrane of the fuel gas humidifier 20 may be used.

  As described above, the fuel cell system according to the present invention improves the energy efficiency of the entire system, and can be downsized and stably operated, and can be applied to electric vehicles and the like.

Schematic diagram showing the configuration of the fuel cell system according to Embodiment 1 of the present invention. Explanatory drawing of the structure of the humidifier in the same Embodiment 1, and a wet heat exchange effect Description perspective view of the configuration of the humidifier and wet heat exchange action in the first embodiment Description perspective view of the configuration of the humidifier and wet heat exchange action in the first embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st air path 2 2nd air path 3 3rd air path 4 1st discharge | emission oxidant gas path 5 2nd discharge | emission oxidant gas path 6a 1st cooling water path 6b 2nd cooling water path 6c Third cooling water path 7 Cooling water path 11 Fuel cell 12 Cooling water pump 13 Cooling water radiator 14 Cooling water tank 15 Hot water storage path 20 Fuel gas humidifier 21 Second oxidant gas humidifier 22 First oxidation Oxidant gas humidifier 23 Moisture transfer film 50 Oxidant gas humidifier 51 Oxidant / fuel gas humidifier 63 Oxidant gas end plate 76 Casing 77 First flow path plate 84 Exhaust fuel gas through hole 102 Through hole

Claims (2)

A fuel cell that generates power using fuel gas and oxidant gas, a fuel gas humidifier that humidifies the supply fuel gas supplied to the fuel cell, and an oxidation that humidifies the supply oxidant gas supplied to the fuel cell containing gas humidifier, a fuel cell system which have a cooling water passage through which cooling water flows for cooling the heat generated during power generation of the fuel cell,
Cooling water flowing through the cooling water path, after heating the supply fuel gas in the fuel gas humidifier, while humidifying the supply oxidant gas in the oxidant gas humidifier,
The exhaust fuel gas discharged from the fuel cell passes through a through hole penetrating the inside of the oxidant gas humidifier, and is then humidified by the fuel gas humidifier, and is discharged to the outside of the humidifier. A fuel cell system provided and configured. The oxidant gas humidifier includes a first oxidant gas humidifier and a second oxidant gas humidifier,
The second oxidant gas humidifier is disposed between the fuel gas humidifier and the first oxidant gas humidifier;
In the exhaust fuel gas path, the exhaust fuel gas passes through the through hole provided in at least one of the first oxidant gas humidifier and the second oxidant gas humidifier, and then the fuel 2. The fuel cell system according to claim 1, wherein the exhaust fuel gas path is configured so as to be humidified by a gas humidifier and to flow out of the humidifier.

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