JP2008041537A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system of higher durability and power generation performance of a stack by preventing drifting of low moisture gas in a humidifier even during low electric energy of the fuel cell system, so that the low moisture gas gains sufficient amount of humidification. <P>SOLUTION: The flow-in surface and flow-out surface are formed for low moisture gas at both ends in lengthwise direction of a hollow fiber membrane humidifier 71. A flow path blocking member 81 is provided at the center of either the flow-in surface or flow-out surface. So, the flow path of low moisture gas can be regulated against drifting of a high moisture gas to provide sufficient amount of humidification stably at all times. Thus, power generation performance of a stack and durability are raised. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system provided with a humidifier, and more particularly, to a fuel cell system provided with a humidifier that allows a low-humidity gas to suitably recover moisture from a high-humidity gas and obtain a humidification amount. It is.

  In a fuel cell system, power generation and heat generation are performed by reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen in the fuel cell. The heat generated by the fuel cell is conveyed by circulating the cooling water, and the temperature of the fuel cell is maintained within a predetermined temperature range suitable for power generation. Further, the heat of the cooling water is used in a water heater or the like. By doing so, the energy efficiency of the fuel cell system can be improved.

  Further, in the fuel cell system, in order to change the power generation amount according to the required power amount, the operating state can be changed by adjusting the fuel gas flow rate, the oxidant gas flow rate, the cooling water flow rate, and the like.

  Further, in the polymer electrolyte fuel cell, a solid polymer electrolyte membrane having proton conductivity is used as an electrolyte. However, this solid polymer electrolyte membrane needs to be in a highly wet state, and is in a dry state or a state of insufficient wetness. Then, since proton conductivity deteriorates and power generation performance deteriorates and durability deteriorates, fuel gas or oxidant gas is humidified from a low wet state to a high wet state by a humidifying means and supplied to the fuel cell. Is going to do.

  As a humidifying device for low-humidity gas using fuel gas or oxidant gas, there is one disclosed in Patent Document 1, for example.

  FIG. 9 shows a hollow fiber membrane humidifier 71 provided inside the humidifier 21a. The hollow fiber membrane humidifier 71 includes a cylindrical housing 72, a hollow fiber membrane bundle accommodated in the housing 72, and It is comprised including in the center part of this hollow fiber membrane bundle. The peripheral wall of the housing 72 is provided with a plurality of openings located in the vicinity of both ends thereof. The opening indicated by reference numeral 74 is a high-humidity gas inlet, and the opening indicated by reference numeral 75 is a high-humidity gas outlet. One end of the housing 72 indicated by reference numeral 76 is a low wet gas inflow port, and the other end of the housing 72 indicated by reference numeral 77 is a low wet gas outflow port.

  On the other hand, the hollow fiber membrane bundle accommodated in the housing 72 is configured by bundling thousands of hollow fiber membranes 80 having the hollow passages 80a shown in FIG. The hollow passage 80a of the hollow fiber membrane 80 is secured on the end side of the opening in the direction), and is fixed with an adhesive so as not to be scattered. Portions where the hollow fiber membrane bundle is bonded to the housing 72 are referred to as potting portions 78 and 79. The potting portions 78 and 79 allow the wet fiber membrane bundle to pass through a hollow passage 80a inside the hollow fiber membrane bundle 73. The gas and the highly humid gas flowing outside the hollow fiber membrane 80 are not mixed.

  And the humidifier 21a is comprised by incorporating the hollow fiber membrane humidifier 71 comprised as mentioned above in the cylindrical case 210 as shown in FIG.

  That is, seal rings (hereinafter referred to as O-rings) 211, 212, and 213 are respectively provided at both ends and an intermediate portion of the outer periphery of the hollow fiber membrane humidifier 71, and the case 210 is formed by the O-rings 211, 212, and 213. The air path 301a and the exhaust air path 361b are partitioned in the case 210 when assembled into the case 210.

  With this configuration, the air from the air supply device 20 flows through the air filter 32 and the main air path 30 and flows into the case 210 from the air path 30a. The low-humidity gas outlet port passes through the hollow passages 80a of the hollow fiber membranes 80 constituting the hollow fiber membrane humidifier 71 from the low-humidity gas inlet port 76 opened to the air passage 301a located in the front stage in the case 210. 77 flows from the air path 30a through the air path 301a located at the rear stage. This flow is indicated by a white arrow as a low wet gas flow.

  On the other hand, the high-humidity air that has passed through the main exhaust air path from the fuel cell and has flowed into the case 210 from the air inflow path 36 a passes through the exhaust air path 361 a in the previous stage partitioned by the O-ring 212 to the hollow fiber membrane humidifier 71. It passes through the high-humidity gas inlet 74, flows through the gap formed on the outer surface of the dense hollow fiber membrane 80, flows into the exhaust air passage 361b in the subsequent stage, and passes through the air exhaust passage 36b from here to the exhaust main air passage. Flowing. This flow is indicated by a black arrow as a flow of highly humid gas.

  The temperature and humidity exchange between the low wet gas and the high wet gas is performed by both flows in the humidifier 21a. That is, in the hollow fiber membrane humidifier 71 of the humidifier 21a, the high-humidity gas of high temperature and high humidity exchanges heat with the low-humidity gas of low temperature and low humidity via the membrane structure of the hollow fiber membrane 80, and at the same time Through the membrane structure, moisture moves to a low wet gas.

As a result, the air (low wet gas) supplied to the fuel cell is in a state where both temperature and humidity are increased, and becomes an oxidant gas that suppresses deterioration of the electrolyte membrane of the fuel cell.
JP 2002-289229 A

However, if a humidifier having such a configuration and action is used to recover the moisture from the high-humidity gas and supply the sufficiently humidified gas to the fuel cell stack, the low-humidity gas is hollow. If the filling rate of the yarn membrane bundle is not more than a certain value (40% or more), the membrane hangs down in the case and the membrane is broken, so the gap between the hollow fiber membranes is very small. Therefore, the high-humidity gas flows in a direction perpendicular to the longitudinal direction of the hollow fiber membrane bundle, but particularly when the high-humidity gas flows at a low flow rate during low power generation, the resistance of the hollow fiber membrane is large. The gap outside the hollow fiber membrane could not pass uniformly in the vertical direction, and it was concentrated and circulated in the gap between the outer surface portion of the hollow fiber membrane bundle and the upstream side portion of the highly humid gas.

  In the operating state of the fuel cell, the power generation amount is set by a predetermined program set in consideration of the power load and the like. The amount of power generated by the fuel cell is determined by the flow rates of oxidant gas (for example, air) and fuel gas (hydrogen) when the electrode area, current density, and number of stages are constant. The flow rates of the oxidant gas and the fuel gas are smaller than those at the time of setting.

  In the hollow fiber membrane, the high wet gas discharged from the fuel cell recovers the moisture of the supply gas from the outside of the membrane to the low wet gas inside the hollow fiber membrane. Since the temperature is low, water condenses inside the hollow fiber membrane. At this time, the water condensed inside the hollow fiber membrane is pumped and discharged by the air supply device, but the water condensed inside the hollow fiber membrane cannot be completely discharged, especially at a low flow rate during low power generation. Water tends to stay, so-called flooding phenomenon occurs, condensed water stays, and low wet gas cannot flow inside the hollow fiber membrane. The low wetting gas drifts away from the inside of the hollow fiber membrane where the flooding phenomenon of the hollow fiber membrane bundle has occurred, and it is not very in contact with the high wet gas in the membrane of other hollow fiber membranes with relatively little flooding. It distributes selectively in the center part of the longitudinal section of the hollow fiber membrane bundle. That is, the low wet gas that has circulated through the hollow fiber membrane bundle cannot sufficiently collect moisture with the high wet gas, so that the low wet gas cannot obtain a predetermined humidification amount. This is not preferable because the supply gas with insufficient moisture reacts with the electrolyte membrane of the fuel cell, and accelerates the deterioration of the electrolyte membrane.

  That is, the hollow fiber membrane bundle collects moisture from the high-humidity gas with the membrane on the outer peripheral surface portion, but the membrane in the central portion hardly collects moisture, and conversely, the low-humidity circulating in the membrane in the central portion. In order to dry and dilute the moisture recovered by the gas, there has been a problem that a sufficiently humidified gas cannot be supplied to the fuel cell stack.

  The present invention solves the above-described conventional problems, prevents uneven flow of a low-humidity gas in a humidifier even during low power generation of a fuel cell, and circulates in the membrane at the center of the hollow fiber membrane bundle. It is an object of the present invention to provide a fuel cell system that can sufficiently secure the humidification amount of at least one of the fuel gas and the oxidant gas supplied to the fuel cell without drying and diluting the moisture recovered by the gas.

  In order to solve the problem related to the conventional fuel cell not being able to ensure a sufficient amount of humidification during low power generation, the fuel cell system of the present invention generates power using a fuel gas containing hydrogen and an oxidant gas containing oxygen. A oxidant gas humidifier that humidifies an oxidant gas supplied to the fuel cell, the oxidant gas humidifier includes a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled, and The hollow fiber membrane bundle has a case for accommodating the low-humidity gas inflow surface and outflow surface at both ends of the hollow fiber membrane bundle, and the low-wetness is formed on either the inflow surface or the outflow surface. A flow path closing member for closing the gas flow path is provided, and the high-humidity gas discharged from the fuel cell is circulated inside the case and outside the hollow fiber membrane, and inside the hollow fiber membrane. Low humidity supplied to the fuel cell By circulating the scan, the fuel cell system characterized by a water content of the high humid gas is shifted to the low wet gas humidifies the low wet gas.

  The fuel gas humidifier comprises: a fuel cell that generates power using a fuel gas containing hydrogen and an oxidant gas containing oxygen; and a fuel gas humidifier that humidifies the fuel gas supplied to the fuel cell. A hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled, and a case that accommodates the hollow fiber membrane bundle, and an inflow surface and an outflow surface of the low wet gas are formed at both ends of the hollow fiber membrane bundle, A flow path closing member that closes the flow path of the low-humidity gas is provided on one of the inflow surface and the outflow surface, and is discharged from the fuel cell inside the case and outside the hollow fiber membrane. The high-humidity gas is circulated, and the low-humidity gas supplied to the fuel cell is circulated inside the hollow fiber membrane, thereby transferring the moisture in the high-humidity gas to the low-humidity gas. Fuel cell characterized by humidification Stem to.

  With this configuration, even at the time of low power generation of a fuel cell in which the flow rate of at least one of the fuel gas and the oxidant gas is low, the moisture recovered by the low-humidity gas flowing through the membrane at the center of the hollow fiber membrane bundle is dry diluted. In addition, it is possible to maintain the contact area between the bundle of hollow fiber membranes and the high-humidity gas that can sufficiently secure the humidification amount of at least one of the fuel gas and the oxidant gas supplied to the fuel cell.

  According to the present invention, the low-humidity gas of the supply gas can recover a sufficient amount of water, and the supply gas of the appropriate humidification amount can be always supplied to the fuel cell stack for any power generation amount. It is possible to ensure the power generation performance of the fuel cell and to prevent deterioration of durability.

  The invention described in claim 1 is a fuel cell that generates power using a fuel gas containing hydrogen and an oxidant gas containing oxygen, and an oxidant gas humidifier that humidifies the oxidant gas supplied to the fuel cell. The oxidant gas humidifier includes a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled, and a case for housing the hollow fiber membrane bundle, and the low wet gas is provided at both ends of the hollow fiber membrane bundle. An inflow surface and an outflow surface are provided, and a flow path closing member that closes the flow path of the low-humidity gas is provided on one of the inflow surface and the outflow surface, and the hollow fiber is provided inside the case. A high wet gas discharged from the fuel cell is circulated outside the membrane, and a low wet gas supplied to the fuel cell is circulated inside the hollow fiber membrane, thereby reducing the moisture in the high wet gas. Move to wet gas and humidify low wet gas Is obtained by a fuel cell system characterized and.

  According to such a configuration, the flow path portion that does not flow due to the uneven flow of the high wet gas does not flow the low wet gas due to the blocking member, and therefore flows in the membrane at the center of the hollow fiber membrane bundle even during low power generation of the fuel cell. Without drying and diluting the moisture collected by the low-humidity gas, it is possible to sufficiently secure the humidification amount of the low-humidity gas of the oxidant gas supplied to the fuel cell, and to prevent deterioration of durability.

  The invention according to claim 2 includes a fuel cell that generates power using a fuel gas containing hydrogen and an oxidant gas containing oxygen, and a fuel gas humidifier that humidifies the fuel gas supplied to the fuel cell. The fuel gas humidifier has a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled, and a case for housing the hollow fiber membrane bundle, and the low wet gas inflow surface is provided at both ends of the hollow fiber membrane bundle. And a flow path closing member that closes the flow path of the low-humidity gas is provided on one of the inflow surface and the outflow surface, and is provided inside the case and outside the hollow fiber membrane. The high-humidity gas discharged from the fuel cell is circulated through the hollow fiber membrane, and the low-humidity gas supplied to the fuel cell is circulated inside the hollow fiber membrane. To moisten the low-humidity gas It is obtained by a fuel cell system according to symptoms.

  According to such a configuration, the flow path portion that does not flow due to the uneven flow of the high wet gas does not flow the low wet gas due to the blocking member, and therefore flows in the membrane at the center of the hollow fiber membrane bundle even during low power generation of the fuel cell. Without drying and diluting the moisture collected by the low-humidity gas, it is possible to sufficiently secure the humidification amount of the low-humidity gas of the fuel gas supplied to the fuel cell and to prevent deterioration of durability.

  A third aspect of the present invention is the fuel cell system according to the first or second aspect of the present invention, wherein the flow path closing member is constituted by a core material penetrating the hollow fiber membrane bundle.

  According to such a configuration, an unnecessary membrane that does not collect moisture is not used by the low-humidity gas of the supply gas, so that the cost of the membrane can be reduced.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the flow path blocking member provided on either the inflow surface or the outflow surface of the hollow fiber membrane bundle is The downstream side of the high wet gas is more closed than the upstream side.

  According to such a configuration, the flow path portion that does not circulate due to the uneven flow of the high-humidity gas does not circulate the low-humidity gas due to the blocking member, and circulates only through the high-humidity gas circulation portion. Without humidifying the water collected by the low-humidity gas flowing through the membrane in the center of the hollow fiber membrane bundle, the amount of humidification of the low-humidity gas at least one of the fuel gas and the oxidant gas supplied to the fuel cell is sufficiently It is possible to ensure and prevent deterioration of durability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the present embodiment.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a configuration of a fuel cell system according to Embodiment 1 of the present invention, FIG. 2 is a configuration diagram showing a hollow fiber membrane humidifier according to Embodiment 1, and FIG. 3 is a hollow fiber membrane humidifier of FIG. FIG. 4 is a configuration diagram of a hollow fiber membrane used in the hollow fiber membrane humidifier, and FIG. 5 is a longitudinal section of a humidifier equipped with the hollow fiber membrane humidifier. FIG. 6 and FIG. 6 are longitudinal sectional views showing other configurations of the humidifying device provided with the hollow fiber membrane humidifier.

  As shown in FIG. 1, the fuel cell system of the present embodiment includes an air supply device 20, an air humidifier 21 that is an oxidant gas humidifier, a fuel cell 19, a fuel supply device 23, and a fuel processing device. 24, the fuel gas humidifier 25, the heat exchanger 26, the cooling water tank 27, the cooling water pump 28, and the hot water storage tank 29 are comprised as main elements.

  Oxidant gas (air in the embodiment of the present invention) from the air supply device 20 is removed from impurities such as nitrogen oxide and sulfur oxide in the atmosphere by the air filter 32, and passes through the air path 30 to form the oxidant. It is supplied to the air humidifier 21 which is a gas humidifier. The air supplied to the air humidifier 21 is humidified by the air humidifier 21 that has passed through the first air path 30 in accordance with the amount of power generated by the fuel cell 19, and the air that has passed through the air humidifier 21 is oxidant gas. Is supplied to the cathode electrode of the fuel cell 19 through the air path 31.

  Of the air supplied to the fuel cell 19, the air that has not been used for the reaction is supplied to the humidifier 21 via the exhaust air path 36 and uses moisture and heat contained in the supplied exhaust air. Thus, the air supplied to the fuel cell 19 as the oxidant gas is humidified and heated. Then, the exhaust air that has passed through the humidifier 21 is exhausted through the exhaust air path 37.

  Here, air has been described as an example of the oxidant gas. However, any gas containing oxygen can be used as the oxidant gas.

  On the other hand, the fuel processing device 24 includes, for example, city gas, propane, methane, natural gas, or the like gas containing a compound composed of at least carbon and hydrogen, or alcohol through the fuel path 33 from the fuel supply device 23. A raw material gas such as is supplied. In the fuel cell system of the present embodiment, a case where city gas is used as a raw material gas will be described.

  In addition, although not specifically shown, the fuel processor 24 generates a reformed gas containing hydrogen by a reforming reaction, and converts carbon monoxide in the reformed gas by a shift reaction. This is a generally known configuration in which a reforming section for reducing and a purifying section for further reducing carbon monoxide in the reformed gas that has passed through the transforming section by a selective oxidation reaction are provided. By heating the raw material in an atmosphere containing water vapor, a hydrogen-rich fuel gas is generated. The hydrogen-rich fuel gas is supplied to the fuel gas humidifier 25 via the fuel gas path 34 and humidified.

  Furthermore, the fuel gas humidifier 25 is a humidifier that performs the same heating and humidification operations as the air humidifier 21, and has the same configuration as the air humidifier 21.

  The hydrogen-rich gas humidified by the fuel gas humidifier 25 is supplied to the anode electrode side of the fuel cell 19 through the fuel gas path 35 as the fuel gas of the fuel cell 19. In the fuel cell 19, electricity is generated by the reaction between the air supplied to the cathode electrode side and the fuel gas supplied to the anode electrode side, and electricity and heat are generated.

  Of the fuel gas supplied to the fuel cell 19, the fuel gas that has not been used for the reaction is supplied to the fuel gas humidifier 25 via the exhaust fuel gas path 38 a, and the fuel cell in the fuel gas humidifier 25. After being used for heating and humidification of the fuel gas before being supplied to the fuel gas 19, the fuel gas is supplied to the combustion section of the fuel processing device 24 via the exhaust fuel gas passage 38b, where the raw material is reformed into fuel gas. It is used for heating the device 24.

  Further, in order to remove the heat generated in the fuel cell 19, the cooling water in the cooling water tank 27 is supplied to the fuel cell 19 by the cooling water pump 28 via the cooling water path 39.

  Then, the cooling water heated in the fuel cell 19 is supplied to the heat exchanger 26 via the cooling water passage 41. In the heat exchanger 26, since the water stored in the hot water storage tank 29 is supplied by the hot water storage pump 42 via the hot water circulation path 43, the cooling water is cooled by the heat exchange in the heat exchanger 26, and conversely. Water from the hot water storage tank 29 is heated, and hot water is stored in the hot water storage tank 29 by this repetition.

  The cooling water discharged from the cooling water tank 27 is heated by the heat generated along with the power generation in the fuel cell 19 and is cooled again by exchanging heat with the hot water storage in the heat exchanger 26. However, the amount of heat generated in the fuel cell 19 is Since there is a correlation with the power generation amount, the operation of the cooling water pump 28 is controlled to supply a cooling water flow rate according to the power generation amount, and further, the hot water storage water pump 42 adjusts the hot water storage water flow rate. The temperature and the water temperature in the cooling water tank 27 are maintained at a predetermined temperature.

  Next, an air humidifier 21 that is an oxidant gas humidifier, which is a feature of the first embodiment, will be described. FIG. 2 shows a hollow fiber membrane humidifier provided inside the air humidifier 21, and the hollow fiber membrane humidifier 71 includes a cylindrical housing 72 and a hollow fiber membrane bundle 73 accommodated in the housing 72. It is comprised including. The peripheral wall of the housing 72 is provided with a plurality of openings located in the vicinity of both ends thereof. The opening indicated by reference numeral 74 is a high-humidity gas inlet, and the opening indicated by reference numeral 75 is a high-humidity gas outlet. One end of the housing 72 indicated by reference numeral 76 is a low wet gas inflow port, and the other end of the housing 72 indicated by reference numeral 77 is a low wet gas outflow port.

  On the other hand, the hollow fiber membrane bundle 73 accommodated in the housing 72 is configured by bundling thousands of hollow fiber membranes 80 having the hollow passages 80a shown in FIG. While securing the hollow passage 80a of the hollow fiber membrane 80 on the end side of the opening in the circumferential direction), it is fixed with an adhesive so as not to be scattered. Portions where the hollow fiber membrane bundle 73 is bonded to the housing 72 are referred to as potting portions 78 and 79, and the potting portions 78 and 79 allow the low wetting state in which the hollow fiber membrane bundle 73 is circulated through the hollow passage 80 a. The high-humidity gas that circulates outside the hollow fiber membrane 80 is prevented from being mixed.

  Incidentally, in such a hollow fiber membrane humidifier 71, a bundle of a predetermined number of hollow fiber membranes 80 is inserted into the housing 72, and both sides of the hollow fiber membrane humidifier 71 are sufficiently bonded and fixed with an adhesive. It is created by cutting and removing a bundle of membranes 80.

  Further, as the hollow fiber membrane humidifier 71, a hollow fiber membrane 80 having an inner diameter of 0.5 to 1.5 mm and an outer shape of 0.7 to 1.7 mm in the housing 72 is 20 to 60% of its internal volume. Filled in proportion.

  Accordingly, in the hollow fiber membrane humidifier 71, a minute passage space is secured on the outer periphery of each hollow fiber membrane 80, and the hollow passage 80a of each hollow fiber membrane 80 is compressed and crushed without being crushed. The area is secured.

  Reference numeral 81 denotes a flow path closing member, which is positioned as a core material whose both ends are closed in the longitudinal direction of the hollow fiber membrane bundle 73, and the flow of the high-humidity gas from the center in the longitudinal section of the hollow fiber membrane humidifier 71. It can arrange | position in the downstream of this.

  And the air humidifier 21 is comprised by incorporating the hollow fiber membrane humidifier 71 comprised as mentioned above in the cylindrical case 210 as shown in FIG.

  That is, seal rings (hereinafter referred to as O-rings) 211, 212, and 213 are respectively provided at both ends and an intermediate portion of the outer periphery of the hollow fiber membrane humidifier 71, and the case 210 is formed by the O-rings 211, 212, and 213. The air path 301a and the exhaust air path 361a are partitioned in the case 210 when assembled into the case 210.

  With this configuration, the air from the air supply device 20 flows through the air filter 32 and the air path 30 and flows into the case 210. Then, the low wet gas inlet 76 opened in the case 210 passes through the hollow passages 80a of the hollow fiber membranes 80 constituting the hollow fiber membrane humidifier 71, and the air path is located downstream from the low wet gas outlet 77. It flows with the air path 30a via 301a. This flow is indicated by a white arrow as a low wet gas flow.

  On the other hand, the high-humidity air flowing from the fuel cell 19 through the exhaust air path 36 into the case 210 flows from the upstream exhaust air path 361 a partitioned by the O-ring 212 to the high-humidity gas flow of the hollow fiber membrane humidifier 71. It passes through the inlet 74, passes through a gap formed on the outer surface of the dense hollow fiber membrane 80, flows into the exhaust air passage 361b at the subsequent stage, and flows from here to the exhaust air passage 37 through the exhaust air passage 36b. This flow is indicated by a black arrow as a flow of highly humid gas.

  The heat / humidity exchange between the low-humidity gas and the high-humidity gas is performed by both flows in the air humidifier 21. That is, in the hollow fiber membrane humidifier 71 of the air humidifier 21, the high-humidity gas of high temperature and high humidity exchanges heat with the low-humidity gas of low temperature and low humidity via the membrane structure of the hollow fiber membrane 80, At the same time, the moisture passes through the membrane structure and moves to a low-humidity gas.

  As a result, the air (low wet gas) supplied to the fuel cell 19 is in a state where both temperature and humidity are increased, and becomes an oxidant gas that suppresses the deterioration of the electrolyte membrane of the fuel cell 19.

  Regarding the operation of the fuel cell system configured as described above, the operation of the air humidifier, which is a feature of the first embodiment, will be described below.

  When the low-humidity gas of the supply gas supplied to the fuel cell 19 is discharged from the fuel cell 19, the air humidifier 21 is heated and heated by the heat and generated water generated by the power generation in the fuel cell 19. Moist heat exchange with humidified exhaust air. Then, the humidified air flowing through the air path 30 heated and humidified by the wet heat exchange leaves the air humidifier 21 and is supplied from the air path 30 to the fuel cell 19.

  On the other hand, the operating state of the fuel cell 19 sets the power generation amount by a predetermined program set in consideration of the power load and the like. Since the power generation amount of the fuel cell 19 is determined by the flow rates of the oxidant gas (air) and the fuel gas (hydrogen) when the electrode area, current density, and the number of stages are constant, the high power generation amount is set when the low power generation amount is set. Compared to the case, the flow rates of the oxidant gas and the fuel gas are small.

  In the hollow fiber membrane 80, the high wet gas discharged from the fuel cell 19 recovers the moisture of the supply gas from the outside of the membrane to the low wet gas inside the hollow fiber membrane 80. Since water has a lower temperature than the outside, water condenses inside the hollow fiber membrane 80. At this time, the water condensed inside the hollow fiber membrane 80 is pumped and discharged by the air supply device 20, but the water condensed inside the hollow fiber membrane 80 cannot be completely discharged when the flow rate is low during low power generation. Condensed water tends to stay in the water, so-called flooding phenomenon occurs, the condensed water stays, and the low wet gas cannot flow inside the hollow fiber membrane 80. The low wet gas drifts away from the inside of the hollow fiber membrane in which the flooding phenomenon occurs in the hollow fiber membrane bundle 73, and is not in contact with the high wet gas in the other hollow fiber membranes with relatively little flooding. The hollow fiber membrane bundle 73 that has not been circulated selectively in the center of the longitudinal section.

  That is, the low wet gas that has circulated through the hollow fiber membrane humidifier 71 cannot sufficiently recover the moisture with the row wet gas, and thus the low wet gas cannot obtain a predetermined humidification amount. This is not preferable because the supply gas with insufficient moisture reacts with the electrolyte membrane of the fuel cell 19 and promotes deterioration of the electrolyte membrane.

  In the hollow fiber membrane humidifier 71, the flow path closing member 81 is disposed at the center of the low wet gas inlet 76 and the low wet gas outlet or below the low wet gas outlet, that is, downstream of the high wet gas. Thus, the low wet gas can be forced to flow through the outer peripheral portion of the hollow fiber membrane bundle through which the high wet gas flows (see FIG. 7).

  As described above, the air humidifier 21 can always supply an appropriate amount of humidified gas (oxidant gas) to the fuel cell stack even when the low-humidity gas has a low flow rate, regardless of the amount of power generated by the fuel cell 19. In addition, the power generation performance of the fuel cell 19 can be ensured, and deterioration of durability can be suppressed.

  Further, as shown in FIG. 6, the flow path closing member of the present embodiment is a disc member (flow path closed in FIG. 6) disposed on at least one surface of the low wet gas inlet 72 or the low wet gas outlet 73. The member 82) may be used.

  In the present embodiment, the humidified gas is the oxidant gas, but the same effect can be obtained by using the fuel gas.

  As described above, the fuel cell system according to the present invention can also be applied to the use of a fuel cell cogeneration system that performs power generation and heat supply using a polymer electrolyte fuel cell.

Schematic diagram showing the configuration of the fuel cell system according to Embodiment 1 of the present invention. The block diagram which shows the hollow fiber membrane humidifier in Embodiment 1 The figure which shows the flow of the highly humid gas which distribute | circulates the inside of the hollow fiber membrane humidifier of the same hollow fiber membrane humidifier of FIG. The block diagram of the hollow fiber membrane used for the hollow fiber membrane humidifier in Embodiment 1 The longitudinal cross-sectional view of the humidification apparatus which comprised the hollow fiber membrane humidifier in Embodiment 1 The longitudinal cross-sectional view which showed the other structure of the humidification apparatus which comprised the hollow fiber membrane humidifier in Embodiment 1 The figure which shows the flow of the highly humid gas which distribute | circulates the inside of the hollow fiber membrane humidifier which showed the other structure of Embodiment 1 of FIG. Graph showing humidification performance in the first embodiment Longitudinal sectional view of a conventional hollow fiber membrane humidifier The figure which shows the flow of the highly humid gas which distribute | circulates in the hollow fiber membrane humidifier which shows a prior art example

Explanation of symbols

19 Fuel cell 21 Air humidifier (oxidant gas humidifier)
25 Fuel Gas Humidifier 71 Hollow Fiber Membrane Humidifier 80 Hollow Fiber Membrane 81 Channel Blocking Member 82 Disc Member (Channel Blocking Member)

Claims (4)

  A fuel cell that generates power using a fuel gas containing hydrogen and an oxidant gas containing oxygen, and an oxidant gas humidifier that humidifies the oxidant gas supplied to the fuel cell, the oxidant gas humidifier Has a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled and a case for accommodating the hollow fiber membrane bundle, and an inflow surface and an outflow surface of the low wet gas are formed at both ends of the hollow fiber membrane bundle. A flow path closing member for closing the flow path of the low-humidity gas is provided on one of the inflow surface and the outflow surface, and is discharged from the fuel cell inside the case and outside the hollow fiber membrane. The high-humidity gas is circulated, and the low-humidity gas supplied to the fuel cell is circulated inside the hollow fiber membrane to transfer the moisture in the high-humidity gas to the low-humidity gas. Fuel cell characterized by humidifying Stem.   A fuel cell that generates power using a fuel gas containing hydrogen and an oxidant gas containing oxygen, and a fuel gas humidifier that humidifies the fuel gas supplied to the fuel cell, the fuel gas humidifier comprising a plurality of fuel cells A hollow fiber membrane bundle in which hollow fiber membranes are bundled, and a case for housing the hollow fiber membrane bundle, and an inflow surface and an outflow surface for the low-humidity gas are formed at both ends of the hollow fiber membrane bundle, A flow path closing member that closes the flow path of the low-humidity gas is provided on any one of the surface and the outflow surface, and the height discharged from the fuel cell inside the case and outside the hollow fiber membrane A wet gas is circulated, and a low-humidity gas supplied to the fuel cell is circulated inside the hollow fiber membrane, whereby moisture in the high-humidity gas is transferred to the low-humidity gas to humidify the low-humidity gas. Fuel cell system .   The fuel cell system according to claim 1, wherein the flow path blocking member is configured by a core material that penetrates the hollow fiber membrane bundle.   The flow path closing member provided on any one of the inflow surface and the outflow surface of the hollow fiber membrane bundle is configured such that the downstream side is more closed than the upstream side of the highly humid gas. The fuel cell system according to any one of the above.

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