JP4027756B2 - Method of humidifying polymer membrane in gas cell humidification system and fuel cell gas humidification system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention comprises a gas humidifier using a water vapor permeable polymer membrane, and in a gas humidification system particularly suitable for a solid polymer fuel cell, a method for humidifying the water vapor permeable polymer membrane, and It relates to a gas humidification system for carrying out the method.
[0002]
[Prior art]
Conventional gas separators using polymer membranes having the property of selectively permeating a specific component gas from a mixed gas composed of various components are disclosed in JP-A-62-274434, JP-A-63-224714, etc. Is known by.
In this type of gas separation apparatus, both ends of a yarn bundle formed by bundling a plurality of gas separation hollow fibers made of the above-described polymer membrane are formed with a heat-resistant thermosetting resin such as an epoxy resin. A yarn bundle element is formed by embedding in a resin wall (potting material) and firmly supporting it, and this yarn bundle element is built in the case body, and the polymer membrane forming the hollow fiber is water vapor permeable. By using a polymer film, it can also be used as a gas humidifier.
[0003]
However, when the conventional gas separation device is used as a gas humidification device, the water vapor permeable polymer membrane that forms the hollow fiber while both ends of the hollow fiber are embedded and fixedly supported in the resin wall Has a large swelling / shrinking behavior in the wet state and the dry state due to its characteristics, and when it is repeatedly used, the hollow fiber repeats wet expansion and dry shrinkage in the radial direction and longitudinal direction, thereby causing the end of the hollow fiber to end. The force repeatedly acts on the fixed portion between the resin wall and the fixed portion, the fixed portion peels off, or a fine crack occurs in the resin wall at the fixed portion, and the hollow fiber and the resin wall in the fixed portion As a result, the gas humidifier may not be able to exhibit sufficient humidification performance, and the product life may be shortened. Ah It was.
In particular, the higher the water vapor permeability of the polymer membrane, the greater the swelling and shrinkage behavior thereof, and the above problems become more serious.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of such problems, and the subject thereof is a water vapor permeability that forms a humidified flow path that can reduce the humidification performance of the gas humidifier and shorten the product life. is to provide a swelling shrinkage behavior that can suppress, humidification method and gas humidification system for the fuel cell of the vapor permeable polymeric membrane in a gas humidification system for a fuel cell of the polymer film.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems, a method for humidifying a polymer membrane in a gas humidification system for a fuel cell according to the present invention includes a hollow case for humidifying a humidified gas supplied to a polymer electrolyte fuel cell. the body comprising a humidifying passage humidified fluid is supplied, and a target humidification flow field for supplying a bridging has been said to be humidified gas is formed by the water vapor permeable polymer membrane humidification passage, the A cathode humidified gas is supplied from the cathode of the fuel cell to the humidified channel from the cathode of the fuel cell to a gas humidifier in which both ends of the humidified channel are hermetically embedded and fixedly supported in a support member made of resin in the case body. Oite the gas humidification system connecting a discharge conduit communicating with the atmosphere for discharging the supply line, the humidified fluid from the humidification passage for supplying a fluid, the forming of the humidification flow path Polymer membrane A method of humidity, inlet and out of the humidified gas to the target humidifying passage is stopped, and stopping the gas humidification system the supply of humidifying fluid is stopped for the humidification flow path from the cathode of the fuel cell The state is characterized in that the polymer film forming the humidified flow path is kept in a wet state by automatically shutting off the discharge pipe and retaining the humidified fluid in the humidified flow path. To do.
[0006]
According to the humidification method described above, the humidified flow path formed by the water vapor permeable polymer membrane is not only in operation of the humidification system, but also the inflow and outflow of the humidified gas is stopped, and the supply of the humidified fluid is stopped. Even when the humidification system is stopped, it can be kept in a swollen state, and the swelling and shrinkage behavior in the radial direction and the longitudinal direction associated with wetting and drying of the humidified flow path can be suppressed. It is possible to prevent the occurrence of problems associated with the swelling and shrinkage behavior of the humidified flow path, such as peeling of the fixing part between the support member and the support member, and to prevent the humidification performance of the gas humidifier from being reduced and shortening the product life Can do.
The humidifying fluid may be any one containing water in a gas phase or a gas-liquid two-phase state.
[0007]
In a specific example of the gas humidifier in the polymer membrane humidification method, the humidification channel is formed by a bundle of hollow fibers made of a water vapor permeable polymer membrane , and the support member is made of a thermosetting resin. It has become . Further, as the water vapor permeable polymer membrane, a fluorine ion exchange membrane having water vapor selective permeability is employed.
[0008]
In the method for humidifying the polymer film, when resuming the inflow / outflow of the humidified gas to / from the humidified flow path, the moisture accumulated in the humidified flow path is removed by air purging the humidified flow path. Once eliminated, it is possible to prevent overhumidification of the humidified gas, which is more preferable.
[0009]
Then, the anode gas containing hydrogen to be supplied to the anode of the upper Symbol fuel cell, it is also possible with Turkey be introduced into the subject humidifying passage as the humidified gas.
[0010]
Further, the humidification method of the polymer film may include an introduction pipe for introducing the humidified gas into the humidified flow path and / or a delivery pipe for sending the humidified gas from the humidified flow path to the fuel cell . A humidified gas control valve for controlling the inflow and outflow of the humidified gas to and from the humidified flow path is provided, and the supply pipe has a humidified gas to the humidified flow path when the humidified gas control valve is closed. Is connected to the cathode of the fuel cell that stops the supply of the humidified fluid to the humidification flow path, and the humidified gas control valve is closed in the exhaust line It can be implemented by a gas humidification system provided with a discharge control valve that automatically shuts off the discharge pipe by detecting the state .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an example of a gas humidifier 1 used in the present invention. In the figure, reference numeral 2 denotes a hollow case body comprising a cylindrical outer cylinder 10 and head caps 11 and 12 respectively attached to both axial ends of the outer cylinder 10 by means such as screwing. A humidifying channel 4 and a humidified channel 5 that is provided in the humidifying channel 4 and is formed of a water vapor permeable polymer film having excellent water permeability are provided therein.
The one head cap 11 is provided with an introduction port 11a for introducing a dry humidified gas 14 such as a gas containing hydrogen or a gas containing oxygen into the humidified flow path 5, for example. The head cap 12 is provided with a delivery port 12a for sending out the humidified gas 14 that has been humidified from the humidified flow path 5. Further, for example, water is supplied to the outer periphery of the outer cylinder 10 from a humidification source. A supply port 10a for supplying a humidifying fluid 16 such as a gas contained in a gas phase or a gas-liquid two-phase state to the humidifying channel 4, and an outlet for discharging the humidifying fluid 16 from the humidifying channel 4 10b.
[0012]
Then, both ends of the humidified flow channel 5 made of a water vapor permeable polymer membrane are embedded in close contact with and firmly supported by the support members 6 and 7 made of resin, and the humidified flow channel 5 and the support member The space between 6 and 7 is hermetically sealed. The support members 6 and 7 are provided in the case body 2 with the introduction side space portion 17 and the delivery side space portion 18 in which the introduction port 11a and the delivery port 12a of the humidified gas 14 are communicated, respectively, and the humidification flow. The humidified flow path 5 penetrates the support members 6 and 7, and both ends thereof open to the introduction-side space portion 17 and the delivery-side space portion 18, respectively. Yes.
[0013]
More specifically, the case body 2 has a pair of head caps 11 and 12 with screws provided on the outer periphery of both ends of the outer cylinder 10 with respect to the openings on both ends of the outer cylinder 10. , 12 are assembled by screwing screws provided on the inner surfaces thereof. Further, cylindrical rings 8 and 9 are airtightly fitted and fixed to both end portions of the inner surface of the outer cylinder, and outer end surfaces thereof are packing 11b provided on the inner surfaces of the head caps 11 and 12, respectively. The airtightness between the screwed portion and the inside of the case body 2 is maintained by abutting on the contact 12b.
[0014]
On the other hand, the humidified flow path 5 is formed by a bundle of a plurality of hollow fibers 5a made of a water vapor permeable polymer membrane having excellent water permeability, such as a fluorine ion exchange membrane. Is a so-called potting material, which is formed of, for example, a thermosetting resin excellent in moldability and sealability, such as an epoxy resin or a polyurethane resin, and both ends of the yarn bundle of the hollow fiber 5a are connected to the support member. 6 and 7 are embedded in an airtight manner and fixedly supported. In fixing the both ends of the hollow fiber 5a to the support members 6 and 7, an adhesive can also be used.
In the rings 8 and 9, support members 6 and 7 for fixing and supporting both ends of the yarn bundle of the hollow fiber 5a are fitted in an airtight manner, and each hollow fiber 5a passes through the support members 6 and 7. Both ends thereof open to the introduction-side space 17 and the delivery-side space 18 formed in the head caps 11 and 12, respectively. Further, in the humidification channel 4 in the outer cylinder 10, the humidified fluid 16 supplied from the supply port 10 a is placed in the humidification channel 4 so as to form a humidified channel 5. A cylindrical guide 3 for guiding the yarn bundle to the discharge port 10b is provided along the longitudinal direction of the yarn bundle.
[0015]
In the gas humidifying apparatus 1 having such a configuration, the humidifying fluid 16 is supplied from the supply port 10a to the humidifying channel 4, and the yarn bundle of the hollow fibers 5a installed in the humidifying channel 4 from the introducing port 11a. When the humidified gas 14 is introduced into the humidified flow path 5 consisting of the above, the humidified gas 14 flows through the hollow fibers 5a and is sent out from the delivery port 12a, while the humidified fluid 16 is sent to the humidified flow path 5a. 4 flows between the hollow fibers 5a along the longitudinal direction of the hollow fibers 5a and is discharged from the discharge port 10b. At this time, the water of the humidified fluid 16 passes through the hollow fibers 5a and is humidified. Since it is taken into the gas 14, the humidified humidified gas 14 is sent out from the delivery port 12a. In addition, the supply port 10a of the humidified fluid 16 is provided on the outlet 12a side of the humidified gas 14 so that the humidified gas 14 and the humidified fluid 16 are in countercurrent contact via the hollow fiber 5a. A discharge port 15 b for the fluid 16 is provided on the inlet 11 a side of the humidified gas 14.
[0016]
FIG. 2 is a schematic view showing an embodiment of the gas humidification system according to the present invention, in which the gas humidifier 1 having the configuration shown in FIG. 1 is applied to the polymer electrolyte fuel cell 20. Is illustrated.
The polymer electrolyte fuel cell 20 is composed of an electrode composed of an anode (anode) 21 and a cathode (cathode) 22 and a polymer electrolyte membrane 23 interposed between the electrodes. The anode gas containing hydrogen is supplied to 21 and the cathode gas containing oxygen is supplied to the cathode 22 through the cathode gas pipe 32, so that the reaction shown in the following equation is caused by the catalytic action of Pt or the like at both electrodes. Done.
Anode: H ₂ → 2H ⁺ + 2e ⁻
Cathode: 2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O
That is, a reaction for converting hydrogen into protons and electrons is performed at the anode 21, and the protons become hydrated (H ⁺ .xH ₂ O) and pass through the polymer electrolyte membrane 23. A reaction for generating water from the proton, oxygen and electrons is performed.
[0017]
Here, the polymer electrolyte membrane 23 is made of, for example, a fluorine ion exchange membrane, and has a property of exhibiting high proton conductivity in a wet state, so that the above reaction can be continuously performed. Needs to maintain the polymer electrolyte membrane 23 in a wet state by humidifying the anode gas and the cathode gas.
Therefore, in this embodiment, the anode gas is introduced into the gas humidifier 1 through the introduction pipe 30 while the cathode 22 is used as a humidification source, and the water generated therein is in a gas phase or a gas-liquid two-phase. The cathode gas after the reaction, that is, the cathode off-gas included in the state is supplied to the gas humidifier 1 through the supply line 34 to humidify the anode gas and then supplied to the anode 21 through the delivery line 31. Yes. Although not shown, the cathode gas is also humidified by an appropriate humidifying means and then supplied to the cathode 22 through the cathode gas conduit 32.
The anode gas that has finished the reaction at the anode is also discharged as an off gas through the anode off gas conduit 33.
[0018]
Specifically, in order to introduce the dried anode gas from the anode gas supply source (not shown) into the humidified flow path 5 as the humidified gas 14 into the introduction port 11a of the humidified flow path 5 in the gas humidifier 1. A feed pipe 31 for sending the anode gas humidified in the gas humidifier 1 to the anode 21 of the fuel cell 20 is connected to the feed outlet 12a. ing. Here, in order to prevent leakage of the anode gas containing hydrogen, as the water vapor permeable polymer film forming the humidified flow path 5, a physical hole is not formed, such as a fluorine ion exchange membrane. A non-porous polymer membrane is used.
Further, a supply line 34 for supplying a cathode off gas containing water from the cathode 22 to the humidification channel 4 as the humidification fluid 16 is connected to the supply port 10a of the humidification channel 4 in the gas humidification device 1, On the other hand, a discharge pipe 35 connected to the atmosphere for discharging the cathode off gas, which has been humidified with the anode gas in the gas humidifier 1, from the humidification flow path 4 is connected to the discharge port 10 b. .
[0019]
The introduction conduit 30 and the delivery conduit 31 are respectively provided with an introduction control valve 30a and a delivery control valve 31a for controlling the inflow and outflow of the anode gas to and from the humidified passage 5 of the gas humidifier 1. In addition, by closing either one or both of these control valves 30a and 31a, the inflow and outflow of the anode gas to and from the humidified flow path 5 can be stopped. When the flow of the anode gas into and out of the humidified flow path 5 is stopped, the supply of the anode gas to the anode 21 of the fuel cell 20 and the generation of water at the cathode 22 are also stopped. The supply of the cathode off-gas as the humidifying fluid 16 to the humidifying channel 4 is also stopped at the same time.
That is, the gas humidification system can be stopped by stopping the inflow and outflow of the anode gas with respect to the humidified flow path 5 by the introduction control valve 30a and / or the delivery control valve 31a.
[0020]
On the other hand, the supply line 34 is provided with a supply control valve for shutting off the supply line 34 and stopping the supply of gas to the humidification channel 4 in a state where the gas humidification system is stopped as described above. 34a is provided. Further, in the state where the gas humidification system is stopped, the exhaust pipe 35 communicated with the atmosphere is shut off, and the humidification flow path 4 is shut off from the atmosphere. A discharge control valve 35 a is provided in the flow path 4 for containing and retaining the cathode off gas containing water.
[0021]
Here, each of the control valves 30a, 31a, 34a, 35a by the control means not shown FIG detects the state of introduction control valve 30a and / or the delivery control valve 31a is closed, the other control valve (supply The control valve 34a and the discharge control valve 35a) may be automatically closed.
Further, a separate control valve may be provided in the cathode gas conduit 32 for supplying the cathode gas to the cathode 22 of the fuel cell 20, and the supply of the cathode gas to the cathode 22 is controlled by controlling the control valve. In addition to this, the supply of the cathode off-gas to the gas humidifier 1 can be controlled. The control valve may be provided in the cathode gas pipe 32 instead of the supply control valve 34a.
[0022]
Next, a method for humidifying the water vapor permeable polymer membrane forming the humidified flow path 5 (the yarn bundle of the hollow fibers 5a) in the gas humidifier 1 using the gas humidification system will be described.
First, the gas humidification system is operating, that is, the introduction control valve 30a and the delivery control valve 31a are opened, and the anode gas flows into and out of the gas humidifier 1 through the introduction line 30 and the delivery line 31. Since the humidified anode gas and cathode gas are supplied to the fuel cell 20 and water is generated at the cathode 22 by the reaction, the supply control valve 34a and the discharge control valve 35a are Cathode off-gas that is opened and is supplied with water from the humidification source to the gas humidifier 1 through the supply pipe 34, and the cathode off-gas that has been humidified in the gas humidifier 1 is It is released into the atmosphere through the discharge pipe 35. Therefore, the water vapor permeable polymer film forming the humidified flow channel 5 installed in the humidified flow channel 4 can be maintained in a wet state.
[0023]
On the other hand, the state in which the gas humidification system is stopped, that is, the introduction control valve 30a and / or the delivery control valve 31a is closed to stop the inflow / outflow of the anode gas with respect to the gas humidifier 1, and as a humidification source In the state where the generation of water at the cathode 22 is stopped and the supply of the cathode off-gas as the humidifying fluid 16 to the humidifying channel 4 is stopped, the supply control valve 34a is closed and the supply line 34 is shut off. Thus, the supply of gas to the humidification channel 4 is stopped. At the same time, the discharge control valve 35a is closed to shut off the discharge conduit 35 communicated with the atmosphere, and the humidification passage 4 is shut off from the atmosphere, so that the cathode off-gas containing water is contained in the humidification passage 4. To stay. Therefore, even when the gas humidification system is stopped, the water remaining in the humidification flow path 4 is not diffused into the atmosphere, and the cover installed in the humidification flow path 4 is the same as during operation. The polymer film forming the humidification channel 5 can be kept in a wet state.
In resuming the inflow / outflow of the humidified flow gas to / from the humidified flow channel and operating the gas humidification system again, the humidified flow channel 5 passes through the polymer membrane while the gas humidification system is stopped. The water accumulated inside is temporarily removed by air purging the humidified flow path 5. By doing so, over humidification of the anode gas can be prevented.
[0024]
As described above, according to the gas humidification system according to the embodiment of the present invention, not only during operation of the gas humidification system but also during stoppage of the gas humidification system, the water vapor permeability is high. The molecular film can be kept in a wet state without being dried, and the swelling and shrinkage behavior of the polymer film can be suppressed. Therefore, the humidified flow path 5, that is, the fixing portion between the both ends of the hollow fiber 5 a and the supporting members 6, 7 is peeled off, or a fine crack is generated in the supporting members 6, 7 at the fixing portion, It is possible to prevent problems that may occur due to the swelling and shrinkage behavior of the polymer film, such as deterioration of the sealing performance between the both end portions of the humidified flow path 5 and the support members 6 and 7. It is possible to prevent the humidifying performance of the humidifying device 1 from being lowered and the product life from being shortened.
[0025]
In the present embodiment wherein the upper Symbol be humidified channel 5 has been formed by the fiber bundle of the hollow fiber 5a made of water vapor permeable polymer film, the pair superimposed water vapor permeable polymeric membrane Of course, it may be formed in various forms such as a laminated shape in which the end portions of each other are coupled together, or a spiral shape in which the ends are wound.
The structure of the gas humidifier 1 is not limited to that shown in FIG. 1 as long as both ends of the humidified flow path 5 are fixedly supported by the support members 6 and 7. For example, to be humidified gas and two or more kinds, of course the us go good be bridged plurality of the humidification passage 5 to it humidification flow path 4 in association.
[0026]
【The invention's effect】
Thus, according to the gas humidification system for humidifying method and a fuel cell of the polymer film in a gas humidification system for a fuel cell according to the present invention, the inflow and out of the humidified gas with respect to the humidification passage is stopped, and, Even when the supply of the humidifying fluid from the cathode of the fuel cell to the humidifying channel is stopped, the gas humidifying system is shut off, and the humidifying fluid is retained in the humidifying channel by blocking the discharge pipe. By preventing the humidified fluid remaining in the passage from being released to the atmosphere, the water vapor permeable polymer film forming the humidified flow path can be kept in a wet state without being dried. The swelling and shrinkage behavior of the film can be suppressed.
Therefore, the fixing portion between the both end portions of the humidified flow path and the support member is peeled off, or a fine crack is generated in the support member at the fixing portion, and both ends of the humidifying flow channel and the supporting member are It is possible to prevent problems that may occur due to the swelling and shrinkage behavior of the polymer film, such as deterioration of the sealing performance between the two, and as a result, the humidification performance of the gas humidifier decreases and the product life is shortened. Can be prevented.
[Brief description of the drawings]
FIG. 1 shows an example of a gas humidifier used in a gas humidification system for a fuel cell according to the present invention.
FIG. 2 is a schematic view showing one embodiment of a gas humidification system for a fuel cell according to the present invention.

Claims (7)

In order to humidify the humidified gas supplied to the solid polymer fuel cell , the humidified flow is formed in a hollow case body by a humidification channel for supplying a humidified fluid and a water vapor permeable polymer membrane. and a target humidification flow field for supplying a bridging has been said to be humidified gas into the road, both end portions of該被humidification passage is formed by buried affixed supported airtightly to a support member made of resin in the body said case A gas humidifier is connected to a supply line for supplying cathode offgas as the humidified fluid from the cathode of the fuel cell to the humidified channel, and to the atmosphere for discharging the humidified fluid from the humidified channel. Oite a discharge line to a gas humidification system that is connected with, a method of humidifying the polymer film forming the object humidification passage,
In the stop state of the gas humidification system in which the inflow / outflow of the humidified gas to / from the humidified flow path is stopped and the supply of the humidified fluid from the cathode of the fuel cell to the humidified flow path is stopped, the discharge pipe A gas humidification system for a fuel cell characterized in that the polymer film forming the humidified flow path is kept in a wet state by automatically shutting off the passage and retaining the humidified fluid in the humidified flow path Method for humidifying polymer membranes. It said the humidification passage is formed by the thread bundle of hollow fibers made of water vapor permeable polymer film for a fuel cell according to claim 1, wherein the support member is characterized in that it consists of a thermosetting resin A method for humidifying a polymer film in a gas humidification system. The method for humidifying a polymer membrane in a gas humidification system for a fuel cell according to claim 1 or 2, wherein the water vapor permeable polymer membrane is a fluorine ion exchange membrane. The water collected in the humidified flow path is temporarily removed by air purging the humidified flow path when resuming the inflow and outflow of the humidified flow gas to and from the humidified flow path. A method for humidifying a polymer membrane in the gas humidification system for a fuel cell according to any one of 1 to 3. The humidification fluid, the humidification method of the polymer film in a gas humidification system for a fuel cell according to claim 1, the water, characterized in that it is intended to include a state of the vapor phase or gas-liquid two-phase . The humidified gases to be introduced into the upper Symbol be humidification passage, the fuel cell according to claim 1, characterized in that the anode gas containing hydrogen to be supplied to the anode of the fuel cell Method for humidifying polymer membrane in gas humidification system for industrial use . A fuel cell gas humidification system for carrying out the humidification method according to claim 1,
Inflow of the humidified gas into the humidified flow path into the introduction conduit for introducing the humidified gas into the humidified flow path and / or the delivery line for sending the humidified gas from the humidified flow path to the fuel cell. A humidified gas control valve for controlling the discharge,
The feed line, in a state where inflow and out of the humidified gas is stopped above with the humidified gas control valve is closed with respect to the humidification passage, the fuel cell to stop the supply of the humidified fluid to the humidified flow path Connected to the cathode ,
The exhaust pipe is provided with a discharge control valve that automatically shuts off the exhaust pipe by detecting a state in which the humidified gas control valve is closed . Gas humidification system.

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