JPH08138705A - Fuel cell humidifier - Google Patents

Abstract

PURPOSE: To prevent drop in power generating capability of a fuel cell by preventing drop in humidifying function caused by hydrogen gas penetrating from a gas flow path side to a water flow path side through a porous film. CONSTITUTION: A hydrogen gas humidifier 20 is constituted with a porous film 21, a catalyst reaction layer 22 formed on its one side surface, and separators 24 which interpose the porous film 21 and the catalyst reaction layer 22 from both sides and form a hydrogen gas flow path 23p and a water flow path 24p respectively. The catalyst reaction layer 22 is formed by dispersing and attaching carbon particles 22b on which platinum 22a is carried on one side surface of the porous film 21. Water in the water flow path 24p permeates the porous film 21 and the catalyst reaction layer 22 according to the difference between the pressure of water flowing in the water flow path 24p and the pressure of hydrogen gas 23p flowing in the hydrogen gas flow path 23p. Hydrogen gas reversely flows from the hydrogen gas flow path 23p side to the catalyst reaction layer 22 through the porous film 21, and the permeated hydrogen gas reacts with oxygen dissolved in water by the action of the platinum 22a and disappears.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell humidifier for humidifying a fuel gas supplied to an electrode of a fuel cell.

[0002]

2. Description of the Related Art In a polymer electrolyte fuel cell, which is one of the fuel cells, the reaction of converting hydrogen gas into hydrogen ions and electrons at the anode and oxygen gas, hydrogen ions and electrons at the cathode are as shown in the following equation. From which water is produced.

Anode reaction: H ₂ → 2H ⁺ + 2e ^- Cathode reaction: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O

The hydrogen ions generated at the anode become hydrated (H ⁺ .xH ₂ O) and move to the cathode in the electrolyte membrane. For this reason, water becomes insufficient in the vicinity of the surface of the electrolyte membrane on the anode side, and in order to continuously carry out the above-mentioned reaction, it is necessary to replenish this insufficient water. The electrolyte membrane used in the polymer electrolyte fuel cell has good electric conductivity in a wet state, but when the water content decreases, the electric resistance of the electrolyte membrane increases and the electrolyte membrane does not sufficiently function as an electrolyte. Will stop the electrode reaction.

This water replenishment is generally performed by humidifying the fuel gas. As a device for humidifying the fuel gas, a device for bubbling the fuel gas to humidify is well known. However, for example, when trying to use this bubbling humidifier for a fuel cell stack mounted on an electric vehicle, a bubbler with a large volume must be prepared and heated by an electric heater, which is practical in terms of volume and energy consumption. Hard to say.

Therefore, as another humidifying device, a device for humidifying the fuel gas through a porous membrane made of tetrafluoroethylene resin has been proposed (for example, Japanese Patent Laid-Open No. 3-269958). This is because water and gas are made to flow through the porous membrane and the pressure of water is made higher than that of gas,
Due to the pressure difference, water is permeated to the gas side through the porous membrane, and the water is vaporized on the surface of the porous membrane to try to humidify the gas.

The humidifying device using such a porous membrane can be incorporated in the solid polymer type fuel cell stack or can be integrally assembled on the outer side of the solid polymer type fuel cell stack. Can be made compact, and since the heat generated by the reaction of the fuel cell can be used as heat for vaporizing water, a heating means such as an electric heater is not required, and the energy consumption is also reduced. Are better.

[0008]

However, in this humidifying device, not only water permeates to the gas side through the porous membrane, but also a phenomenon occurs in which the gas flows back to the water side through the porous membrane. In fact, when the water pressure is much higher than the gas pressure, the reverse flow hardly occurs, but when the pressure difference ΔP between the water pressure and the gas pressure becomes small, the reverse flow becomes large.

On the other hand, since the porous film is thin and has low strength, it has a property of being easily damaged when a large pressure is applied. Considering this property, gas is permeable through the porous film. There is no choice but to tolerate that the water flows back to the water side.

When the gas leaks to the water side, a gas layer is formed between the porous membrane and water, and the humidifying function is deteriorated.
There is a problem that gas is mixed in the water flow path to deteriorate the flow of water. These problems eventually lead to a reduction in the power generation capacity of the fuel cell supplied with the humidified gas.

The humidifying device for a fuel cell of the present invention has been made in view of these problems. It prevents deterioration of the humidifying function and deterioration of the flow of water, and consequently the power generation capacity of the fuel cell. The purpose is to prevent.

[0012]

In order to achieve such an object, the following constitution is adopted as a means for solving the above problems.

That is, the first fuel cell humidifier of the present invention is a humidifier for humidifying the fuel gas supplied to the electrodes of the fuel cell, and is in contact with the water flow path and the fuel gas flow path. A porous membrane that permeates the water according to the pressure difference between the water and the fuel gas, and a catalyst is provided on at least one of the inside of the porous membrane and the surface of the water on the flow channel side. , The summary.

A second fuel cell humidifier of the present invention is a humidifier for humidifying a fuel gas supplied to an electrode of a fuel cell, the humidifier being in contact with a water flow path and the fuel gas flow path. A porous membrane that permeates the water according to the pressure difference between the water and the fuel gas is provided, and a support having water permeability and carrying a catalyst is provided in the water channel. Is the gist.

Here, the fuel gas is hydrogen gas or hydrogen-containing gas supplied to the anode electrode of the fuel cell.

A third fuel cell humidifying device of the present invention is a humidifying device for humidifying a material gas supplied to an electrode of a fuel cell, which is in contact with a reservoir for storing water and a passage for the material gas. A porous membrane that permeates the water according to the pressure difference between the water and the material gas, a gas amount detection unit that detects the amount of the gas that accumulates in the water storage passage, and the accumulated gas A gas vent passage for exhausting gas from the storage passage, an on-off valve for opening and closing the gas vent passage, and a control means for controlling the opening and closing of the on-off valve according to the gas amount detected by the gas amount detecting means. , The summary.

Here, the material gas may be hydrogen gas or hydrogen-containing gas supplied to the anode electrode of the fuel cell, or may be oxygen-containing gas supplied to the cathode electrode.

[0018]

According to the humidifier for a first fuel cell of the present invention having the above-described structure, hydrogen in the fuel gas that has permeated through the porous membrane and appeared on the flow channel side of water is not absorbed by the porous membrane. By contacting with a catalyst provided inside or on at least one of the surfaces of the water on the flow path side, oxygen dissolved in water reacts with the hydrogen to become water. As a result, no gas layer is formed between the porous membrane and water.

When the catalyst is provided on the surface of the porous membrane on the water channel side, the water contributing to the reaction is the water in the water channel, and the catalyst is provided inside the porous membrane. If present, it is water in the porous material that is moving from the water flow path side to the fuel gas side.

According to the second fuel cell humidifier of the present invention, the hydrogen gas that permeates the porous membrane and enters the water channel side is carried on the support provided in the water channel. By coming into contact with the catalyst, oxygen dissolved in water reacts with the hydrogen to become water. As a result, hydrogen gas that has entered the water flow path side is removed.

According to the third fuel cell humidifier of the present invention, the control means opens and closes the on-off valve of the gas vent passage in accordance with the amount of gas accumulated in the water storage passage detected by the gas amount detection means. Control. As a result, the material gas that has permeated the porous membrane and entered the water storage passage is escaped from the gas vent passage.

[0022]

Preferred embodiments of the present invention will be described below in order to further clarify the structure and operation of the present invention described above.

FIG. 1 is a schematic configuration diagram of a power generation system 1 for a polymer electrolyte fuel cell as a first embodiment equipped with a humidifier for a fuel cell according to the present invention. The fuel cell power generation system 1 includes a fuel cell main body 10 including a plurality of battery cells,
A hydrogen gas humidifier 20 that humidifies hydrogen gas, an oxygen-containing gas humidifier 30 that humidifies an oxygen-containing gas (air), and a common water tank 40 that stores water are provided.

The shared water tank 40 is connected to the hydrogen gas humidifier 20 via a pipe 50 and a pressure pump 50P, and the oxygen-containing gas humidifier 3 is connected via a pipe 60 and a pressure pump 60P.
0, and is further connected to the cooling unit 10a of the fuel cell main body 10 via the conduit 70 and the pressurizing pump 70P. Therefore, water is supplied from the shared water tank 40 to the hydrogen gas humidifier 20, the oxygen-containing gas humidifier 30, and the cooling unit 10a.

The hydrogen gas humidifier 20 is connected to an inlet 10b of an anode side flow path (a hydrogen gas flow path 15p described later) of the fuel cell main body 10 via a pipe 80, and the oxygen-containing gas humidifier 30 is connected to a pipe. Inlet 10 of the cathode side flow passage (oxygen gas flow passage 14p described later) of the fuel cell main body 10 via the passage 90.
connected to c. Therefore, the hydrogen gas humidifier 20
The hydrogen gas humidified in (1) is sent to the anode-side flow path of the fuel cell main body 10, and the oxygen-containing gas humidified by the oxygen-containing gas humidifier 30 is sent to the cathode-side flow path of the fuel cell main body 10.
In the figure, 10d is an outlet on the anode side,
e is a cathode side flow path outlet.

The structure of the fuel cell body 10 will be described below. Here, for simplicity, the case where the fuel cell main body 10 is composed of one battery cell will be described first. As shown in the structural diagram of FIG. 2, the battery cell has an electrolyte membrane 11, a cathode 12 and an anode 13 as gas diffusion electrodes which sandwich the electrolyte membrane 11 from both sides to form a sandwich structure, and the sandwich structure from both sides. Separator 14, 15 forming a flow path for an oxygen-containing gas and a fuel gas with the cathode 12 and the anode 13 while sandwiching them.
And the cathode 1 arranged outside the separators 14 and 15.
2 and collector plates 16 and 17 serving as collector electrodes for the anode 13
It is composed of

The electrolyte membrane 11 is an ion exchange membrane made of a polymer material, for example, a fluororesin, and exhibits good electric conductivity in a wet state. The cathode 12 and the anode 13 are made of carbon cloth woven with a yarn made of carbon fiber.
Carbon powder carrying platinum or an alloy of platinum and another metal as a catalyst is kneaded into the gap of the cloth.

The separators 14 and 15 are formed of a dense carbon plate. The separator 14 on the cathode 12 side forms a flow path for the oxygen-containing gas, which is a material gas, with the surface of the cathode 12, and also forms an oxygen gas flow path 14p that serves as a water collection path for water generated in the cathode 12.
The separator 15 on the anode 13 side is the anode 1
The surface of 3 forms a hydrogen gas flow path 15p that forms a flow path for a mixed gas of hydrogen gas as a fuel gas and water vapor. The collector plates 16 and 17 are made of copper (Cu).

This is the basic structure of a single cell. In practice, the separator 14, the cathode 12, the electrolyte membrane 11,
The fuel cell main body 10 is configured by stacking a plurality of sets of the anode 13 and the separator 15 in this order and disposing the current collectors 16 and 17 on the outer side thereof.

The structure of the hydrogen gas humidifier 20 will be described below. As shown in the structural diagram of FIG. 3, the hydrogen gas humidifier 20 includes a porous membrane 21, a catalytic reaction layer 22 provided on one surface of the porous membrane 21, a porous membrane 21 and a catalytic reaction layer 22. And the separators 23 and 24 that form the hydrogen gas and water flow paths 23p and 24p while sandwiching the both sides. The catalytic reaction layer 22 is the water flow path 2
It is located on the side of the separator 24 forming 4p.

The porous film 21 is a polyolefin-based porous film having a porosity of 50% or more and an average pore diameter of about 0.05 μm. The porous membrane 21 allows water to permeate according to the pressure difference between both sides of the film. The porous membrane 21 can be obtained, for example, from Asahi Kasei Kogyo under the trade name “HIPORE 1000”.

As shown in FIG. 4, the catalytic reaction layer 22 is formed by dispersing and adhering carbon particles 22b carrying platinum 22a as a catalyst on one surface of the porous membrane 21.
It adheres on the porous film 21 as follows.

First, the carbon particles 22b are dispersed in an appropriate solvent to prepare a dispersion solution, and then the porous membrane 21 is set in a pressure filtration holder, and the dispersion solution is pressure filtered. As a result, only the solvent passes through the porous film 21, and the carbon particles 22b remain on the surface of the porous film. Then, on the surface of the porous membrane 21 in this state, a small amount of a solution of a proton conductive solid electrolyte (for example, a Nafion 5% solution sold by Aldrich Co., USA) is removed and then hot pressed. As a result, in the process of solidifying the solution of the proton conductive solid electrolyte, the carbon particles 22b are fixed to the surface of the porous film 21 while playing a role as an adhesive. Since this proton conductive solid electrolyte allows water, hydrogen and oxygen to pass therethrough,
Even if the surface of the carbon particles 22b is covered with the proton conductive solid electrolyte, there is no problem.

Carbon particles 22b carrying platinum 22a
Is created by the following method. An aqueous solution of platinum sulfite complex is obtained by mixing an aqueous solution of chloroplatinic acid and sodium thiosulfate. While stirring this aqueous solution, the hydrogen peroxide solution is removed to deposit colloidal platinum particles in the aqueous solution. Next, carbon black as a carrier [eg Vul
While adding can XC-72 (trademark of CABOT Co., USA) and Denka Black (trademark of Denki Kagaku Kogyo Co., Ltd.), the colloidal platinum particles are attached to the surface of the carbon black. Next, the solution is suction-filtered or pressure-filtered to separate the carbon black to which the platinum particles are attached, repeatedly washed with deionized water, and then completely dried at room temperature. Next, the aggregated carbon black is pulverized with a pulverizer and then in a hydrogen reducing atmosphere at 250 ° C. to 3 ° C.
By heating at 50 ° C. for about 2 hours, platinum on carbon black is reduced and residual chlorine is completely removed to complete the platinum catalyst.

In this example, the amount of platinum catalyst supported was 0.01 mg by weight of platinum per cm ^{2 of} the porous membrane.
Has become. The weight of platinum is increased when the gas easily flows back to the water side through the porous membrane 21 (that is, the smaller the pressure difference ΔP between the water pressure and the gas pressure is). If the pressure difference is the same, the platinum weight is increased when a porous membrane having a large amount of humidification per unit area is used. That is, the optimum value of platinum weight may be determined according to the configuration conditions and operating conditions of each humidifier. Further, although platinum is used as the catalyst in the embodiment, it may be replaced with an alloy made of platinum and another metal. Furthermore, in the examples, carbon powder was used as the carrier,
Instead of this, a structure using silica powder, titania powder, alumina powder, or the like may be used.

The separators 23 and 24 are formed of a dense carbon plate which is made by impressing carbon to make it impermeable to gas. Porous film 21 of separators 23 and 24
A plurality of protrusions arranged in parallel are provided on the surface on the side, and the plurality of protrusions and the porous membrane 21 form a plurality of hydrogen gas passages 23p and water passages 24p. In addition, the separators 23 and 24 and the porous film 21 have O-rings 25,
It is sealed by 26, and both sides in the longitudinal direction of the porous membrane 21 are sealed by sealing members 27, 28.

Although the separator 23 is made of gas impermeable carbon in the embodiment, it may be made of any material as long as it is a material that is not attacked by hydrogen gas and has excellent thermal conductivity. Further, the separator 24 may be formed of any material as long as it is a material stable to water and has excellent thermal conductivity.

The inlet of the hydrogen gas flow path 23p of the hydrogen gas humidifier 20 thus constructed is connected to a reformer (not shown), and the outlet of the hydrogen gas flow path 23p is connected to the above-mentioned conduit (fuel cell). Anode side flow path inlet 10b of the main body 10
To a conduit 80). Further, the inlet of the water flow passage 24p of the hydrogen gas humidifier 20 is connected to the pipe 50 leading to the shared water tank 40, and the outlet of the water flow passage 24p is closed. As a result, depending on the difference between the pressure of the water flowing through the water channel 24p and the pressure of the hydrogen gas flowing through the hydrogen gas channel 23p, as shown in FIG. It penetrates the reaction layer 22.
The permeated water vaporizes on the surface of the porous membrane 21 and humidifies the hydrogen gas flowing through the hydrogen gas flow path 23p.

The oxygen-containing gas humidifier 30 has a structure in which the catalytic reaction layer 22 is removed from the hydrogen gas humidifier 20 described above, that is, a structure in which an electrolyte membrane is sandwiched between separators, and detailed description thereof is omitted here. This oxygen-containing gas humidifier 3
When 0, water permeates the porous membrane 121 according to the difference between the pressure on the water side and the pressure on the oxygen-containing gas side. The permeated water vaporizes on the surface of the porous membrane to humidify the oxygen-containing gas.

The fuel cell power generation system 1 configured as described above directly converts chemical energy into electric energy by the above-described chemical reaction, but the hydrogen gas and oxygen humidified by the hydrogen gas humidifier 20 and the oxygen-containing gas humidifier 30 are used. The contained gas facilitates this chemical reaction.

That is, the anode 1 of the fuel cell body 10
In 3, a reaction is performed in which hydrogen becomes an electron with a hydrogen ion, and the generated hydrogen ion combines with water in the vicinity of the anode 13 to be in a hydrated state and move in the electrolyte membrane 11. Therefore, if water is left as it is in the vicinity of the anode 13 of the electrolyte membrane 11, this shortage is replenished by the water vapor in the mixed gas of hydrogen gas and water vapor. As a result, the electrolyte membrane 11 is always in a wet state, and hydrogen ions are not contained in the electrolyte membrane 1.
It is possible to move smoothly in 1 and the cathode reaction is performed smoothly. At the cathode 12, a reaction for producing water is carried out by hydrogen ions, electrons and oxygen. The water vapor in the mixed gas of the oxygen-containing gas and the water vapor is the electrolyte membrane 1
It plays the role of ensuring the wet condition of 1.

As described above in detail, in the fuel cell power generation system 1 of the first embodiment, the hydrogen gas supplied to the fuel cell is humidified by the hydrogen gas humidifier 20. In this hydrogen gas humidifier 20, the catalytic reaction layer 22 is formed on the surface of the porous film 21.
Therefore, as shown in FIG. 4, the hydrogen gas that has permeated the porous film 21 from the hydrogen gas flow path 23p side and reached the catalytic reaction layer 22 is treated in water by the action of the platinum 22a. Reacts with the oxygen dissolved in to form water. As a result, it is possible to prevent a gas layer from being formed between the porous membrane 21 and water by the hydrogen gas flowing back from the hydrogen gas flow path 23p side to the water flow path 24p side. The water generated by the reaction has no adverse effect because it is mixed with the water existing on the water flow path 24p side.

Therefore, it is possible to prevent the humidifying function from being deteriorated by the gas layer, and it is possible to prevent the power generation capacity of the fuel cell main body 10 from being deteriorated.

The second embodiment of the present invention will be described below. FIG. 5 is a schematic diagram of the porous membrane 121 used in the hydrogen gas humidifier of the second embodiment. As shown in FIG. 5, the hydrogen gas humidifier according to the second embodiment does not have the catalytic reaction layer 22 as compared with the hydrogen gas humidifier 20 according to the first embodiment. It has silica particles 122b carrying platinum 122a as a catalyst therein.

The silica particles 122b are the porous film 121.
It is formed in the following manner. First, platinum is supported on the surface of silica particles, which are inorganic fillers, and then a film is formed using this inorganic filler so that platinum is supported inside the membranes. The supported amount of platinum catalyst is the porous membrane 1c.
The platinum weight per m ² may be 0.01 mg.

Although silica powder is used for the inorganic filler as in this embodiment, titania powder or alumina powder can be used in place of silica powder, so long as the cost is not a concern. It is also possible to use zirconia powder, boron nitride powder or aluminum nitride powder. Such a method of supporting a platinum catalyst on the surface of powder is widely and generally performed, and a detailed description thereof will be omitted here.

In the hydrogen gas humidifier of the second embodiment having such a structure, since the silica particles 122b carrying the platinum 122a which is the catalyst are provided inside the porous film 121, the hydrogen gas flow channel side is porous. The hydrogen gas that permeates the membrane 121 and tries to reach the water flow path side is the porous membrane 121.
While passing through the inside of the
Water reacts with oxygen dissolved in water in a normal flow from the water channel side to the membrane channel side to become water. As a result, as in the first embodiment, the water flow path 24p is moved from the hydrogen gas flow path 23p side.
It is possible to prevent a gas layer from being formed between the porous film 21 and water by the hydrogen gas flowing back to the side. Therefore, similarly to the first embodiment, it is possible to prevent the humidifying function from being deteriorated by the gas layer, and it is possible to prevent the power generation capacity of the fuel cell main body 10 from being deteriorated.

The third embodiment of the present invention will be described below. FIG. 6 is a schematic configuration diagram of a fuel cell power generation system 201 as the third embodiment. Compared to the fuel cell power generation system 1 of the first embodiment, this fuel cell power generation system 201 includes a hydrogen gas humidifier 220, a shared water tank 40, and a hydrogen gas humidifier 20 as shown in FIG. The difference is that a holder 300 described later is provided in the connecting pipe 50,
The other configurations are the same. The same parts are designated by the same reference numerals as in the first embodiment.

The hydrogen gas humidifier 220 of this embodiment is similar to the hydrogen gas humidifier 20 of the first embodiment except that the catalytic reaction layer 22 is used.
Except for the porous membrane 21.
It is provided with a structure sandwiched by 3, 24.

The holder 300 will be described below. Figure 7
8 is a perspective view of the holder 300, and FIG. 8 is an exploded perspective view of the holder 300. As shown in both figures, the holder 300
Is the two support screens 301, 3 that are stacked on each other.
Membrane body 3 carrying platinum as a catalyst on one surface of 02
03, and these are packed into two packing 304, 30
It is sandwiched between the inner body 306 and the outer body 307 while improving the sealing property by means of 5. The lock nut 309 and the lock nut 309 are then passed through the lock nut gasket 308.
It is tightened by. The inner body 306
And the outer body 307 is provided with a through hole,
With such a configuration, the holder 300 functions to hold the film body 303 in the middle of the flow path.

The membrane 303 is a polyester non-woven fabric, has a thickness of about 150 [μm], and has water permeability that does not hinder the passage of water. The film body 303 has platinum supported on one surface (both sides may be used, of course). Note that the amount of platinum carried is 1 of the film body 303.
The weight of platinum is about 0.05 [mg] per [cm ² ]. In addition to the polyester type, the film body 303 may be a polyethylene type, polypropylene type, polyamide type, or polysulfone type nonwoven fabric.

The holder 300 having such a structure is provided between the pipe 50 connecting the common water tank 40 and the hydrogen gas humidifier 20, and in particular, in this embodiment, between the pressurizing pump 50P and the hydrogen gas humidifier 20. It is arranged at 50.

As described above in detail, in the fuel cell power generation system 201 of the third embodiment, the hydrogen gas supplied to the fuel cell is humidified by the hydrogen gas humidifier 220. Hydrogen gas enters from the hydrogen gas channel side to the water channel side through the membrane 21. After that, the hydrogen gas advances from the hydrogen gas humidifier 220 to the shared water tank 40 via the pipe line 50. At that time, the hydrogen gas comes into contact with the platinum of the film body 303 provided in the holder 300, and Reacts with the oxygen dissolved in to form water. This allows
The hydrogen gas that has entered the pipeline 50 can be removed.

Conventionally, hydrogen gas that has entered such a pipe deteriorates the flow of water in that pipe or enters the common water tank and mixes into the water flow path of the hydrogen gas humidifier again from the common water tank. Or, if it is mixed in the water flow path of the oxygen-containing gas humidifier, the humidification function of both humidifiers is deteriorated. On the other hand, in the fuel cell power generation system 201 of this embodiment, as described above. Since it is possible to remove the hydrogen gas that has entered the pipeline 50, it is possible to prevent deterioration of the humidification function of the hydrogen gas humidifier 220 and the oxygen-containing gas humidifier 230, and, in turn, the fuel to be humidified. It is possible to prevent the power generation capacity of the battery body 10 from decreasing.

In the third embodiment, the holder 3
00 may be provided in the collecting pipe on the outlet side of the water flow path 24p of the hydrogen gas humidifier 220.

The fourth embodiment of the present invention will be described below. FIG. 9 is a schematic configuration diagram of a hydrogen gas humidification system as the fourth embodiment. As shown in FIG. 9, the hydrogen gas humidifying system 401 mainly includes a humidifier body 410. The humidifier main body 410 has a porous film 421 and a hydrogen gas passage 423p on one side with the porous film 421 interposed therebetween.
And members 423, 42 forming a water flow path 424p on the other side.
4 and.

The hydrogen gas flow path 423p formed by the member 423 is a conduit 430 from the reformer to the fuel cell body.
The water flow path 424p formed by the member 424 has a pressure pump 440 on the inlet side.
It is connected to the water tank 450 through and the outlet side is closed. Further, the control valve 4 is provided in the water channel 424p.
A degassing line 470 provided with 60 is connected. The humidifier main body 410 is arranged such that the outlet side is located above the inlet side.

Further, this hydrogen gas humidifying system 401
From the humidifier body 410 of the line 470 to the control valve 46.
A water level sensor 480, which is provided between 0 and 0, detects the height of the liquid surface of the water flow path 424p, and an electronic control unit 490 electrically connected to the water level sensor 480.

The electronic control unit 490 is a well-known CP.
The microcomputer is composed of a microcomputer including U, ROM, RAM, etc., and controls the opening / closing of the control valve 460 according to the detection signal from the water level sensor 480. Specifically, a predetermined program is stored in advance in the ROM of the electronic control unit 490, and the electronic control unit 490 controls the opening / closing of the control valve 460 according to the program.

The control valve opening / closing process executed by the CPU of the electronic control unit 490 will be described with reference to the flowchart of FIG. As shown in FIG.
The U first takes in the detection signal of the water level sensor 480 (step 500), and determines whether or not the water level indicated by the detection signal is below a predetermined predetermined water level (step 510). Here, when it is determined that the water level is below the predetermined water level, it is determined that a predetermined amount or more of gas has been stored in the water flow path 424p, and a control signal is sent to the control valve 460 to control the control valve 460 to the open state. (Step 520).

On the other hand, when it is determined in step 510 that the water level exceeds the predetermined water level, step 52
0 is skipped and the control valve 460 remains closed. In this way, the processing shown in this routine is once completed.

In the hydrogen gas humidification system 401 configured as described above, when the amount of hydrogen gas that has entered from the hydrogen gas flow passage 423p side to the water flow passage 424p side through the porous membrane 421 reaches a predetermined amount or more, By opening the control valve 460, the hydrogen gas accumulated in the water channel 424p leaks from the degassing conduit 470. Although not shown, the leaked gas is collected and returned to the hydrogen gas system side.

Therefore, it is prevented that a gas layer is formed between the porous film 421 and water by the hydrogen gas that has permeated the porous film 421 and entered from the hydrogen gas flow channel 423p side to the water flow channel 424p side. As a result, similarly to the first embodiment, it is possible to prevent the humidifying function from being deteriorated by the gas layer, and, by extension, the fuel cell main body that is humidified by the hydrogen gas humidifier 410. It is possible to prevent a decrease in power generation capacity.

In the fourth embodiment, the hydrogen gas humidifying system is designed to humidify the hydrogen gas supplied to the anode of the fuel cell. However, instead of this, an oxygen-containing gas supplied to the cathode of the fuel cell is used. May be humidified. That is, the gas flow path 423p is configured to flow the oxygen-containing gas instead of the hydrogen gas. Also with this configuration, it is possible to prevent the humidifying function from being deteriorated by the gas layer, as in the fourth embodiment.

In place of the above-described embodiment, the simplest structure for preventing the formation of a gas layer between the porous membrane and the water flow passage will be described below. The configuration is shown in FIG. As shown in FIG. 11, the hydrogen gas humidifier 600 includes a porous film 621 and hydrogen gas and water channels 623p, 6 while sandwiching the porous film 621 from both sides.
In addition to the separators 623 and 624 forming 24p, the water channel 624p is arranged so as to be on the upper side with respect to the hydrogen gas channel 623p.

FIG. 12 shows an undesirable example. As shown in FIG. 12, when the water flow path is below the hydrogen gas flow path, the gas that has passed through the porous film from the hydrogen gas flow path side and entered the water flow path side is separated into the water flow path and the porous film. In the meantime, gas stays in the gap (in the figure, gas stays in G), so that water cannot contact the porous membrane, and as a result, the internal humidifying function may not work.

On the other hand, in this embodiment, the water flow path 6
Since 24p is arranged so as to be on the upper side with respect to the hydrogen gas flow channel 623p, the gas that has passed through the porous membrane 621 from the hydrogen gas flow channel 623p side and has entered the water flow channel 624p side is the water flow channel 624p. Does not accumulate in the upper side (the side opposite to the porous membrane 621) and the gas thereof does not stay between the water channel 624p and the porous membrane 621. Therefore, it is possible to prevent the deterioration of the humidifying function due to the gas, and it is possible to prevent the power generation capacity of the fuel cell to be humidified from decreasing.

The embodiments of the present invention have been described above.
The present invention is in no way limited to these examples, for example, the porous membrane, instead of a polyolefin film, a cellulose-based, polyamide-based, polysulfone-based, polypropylene-based film, etc. Needless to say, the present invention can be implemented in various modes without departing from the scope of the invention.

[0069]

As described above, in the humidifier for a fuel cell according to the first aspect of the invention, the catalyst provided on at least one of the inside of the porous membrane and the surface on the water flow path side allows the permeation of the porous membrane. The hydrogen gas that appears on the water flow path side can be changed to water. Therefore, it is possible to prevent the deterioration of the humidification function due to the hydrogen gas, and it is possible to prevent the deterioration of the power generation capacity of the humidified fuel cell.

In the fuel cell humidifier of the second aspect,
The hydrogen gas that permeates the porous membrane and enters the flow path of water can be changed to water by the catalyst arranged in the flow path of water. Therefore, the hydrogen gas that has entered the flow path of water can be removed. Therefore, it is possible to prevent the deterioration of the humidification function due to the hydrogen gas, and it is possible to prevent the deterioration of the power generation capacity of the fuel cell to be humidified.

In the humidifying device for a fuel cell according to claim 3,
When the amount of gas that has passed through the porous membrane and entered the water storage passage increases, it can be exhausted to the outside. Therefore, it is possible to prevent the deterioration of the humidifying function due to the gas, and it is possible to prevent the power generation capacity of the fuel cell to be humidified from decreasing.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a power generation system 1 for a polymer electrolyte fuel cell as a first embodiment including a fuel cell humidifier of the present invention.

FIG. 2 is a structural diagram of a battery cell of a fuel cell body.

FIG. 3 is a structural diagram of a hydrogen gas humidifier 20.

FIG. 4 is a schematic view of the vicinity of a catalytic reaction layer 22.

FIG. 5 is a schematic diagram of a porous membrane 121 used in the hydrogen gas humidifier of the second embodiment.

FIG. 6 is a fuel cell power generation system 20 as a third embodiment.
It is a schematic block diagram of 1.

FIG. 7 is a perspective view of a holder 300 used in the third embodiment.

FIG. 8 is an exploded perspective view of a holder 300.

FIG. 9 is a schematic configuration diagram of a hydrogen gas humidification system as a fourth embodiment.

FIG. 10 is a flowchart showing a control valve opening / closing process executed by an electronic control unit 490.

FIG. 11 is a structural diagram of a hydrogen gas humidifier 600 according to another embodiment.

FIG. 12 is a structural diagram of an undesired comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel cell power generation system 10 ... Fuel cell main body 10a ... Cooling part 10b ... Anode side channel inlet 10c ... Cathode side channel inlet 11 ... Electrolyte membrane 12 ... Cathode 13 ... Anode 14 ... Separator 14p ... Oxygen gas channel 15 ... Separator 15p ... Hydrogen gas flow path 16, 17 ... Current collector 20 ... Hydrogen gas humidifier 21 ... Porous membrane 22 ... Catalytic reaction layer 22a ... Platinum 22b ... Carbon particles 23 ... Separator 23p ... Hydrogen gas flow path 24 ... Separator 24p ... Water flow path 25, 26 ... O-ring 27, 28 ... Seal member 30 ... Oxygen-containing gas humidifier 40 ... Shared water tank 50 ... Pipe line 50P ... Pressurizing pump 60 ... Pipe line 60P ... Pressurizing pump 70 ... Pipe line 70P ... Pressure pumps 80, 90 ... Pipeline 121 ... Porous membrane 122a ... Platinum 122b ... Silica particles 201 ... Fuel cell power generation Stem 220 ... Hydrogen gas humidifier 230 ... Oxygen-containing gas humidifier 300 ... Holder 301, 302 ... Support screen 303 ... Membrane 304, 305 ... Packing 306 ... Inner body 307 ... Outer body 308 ... Lock nut gasket 309 ... Lock nut 401 ... Hydrogen gas humidifying system 410 ... Humidifier main body 410 ... Hydrogen gas humidifier 421 ... Porous membrane 423, 424 ... Member 423p ... Hydrogen gas flow path 424p ... Water flow path 430 ... Pipe line 440 ... Pressurizing pump 450 ... Water tank 460 ... Control valve 470 ... Pipe line 480 ... Water level sensor 490 ... Electronic control unit 600 ... Hydrogen gas humidifier 621 ... Porous membrane 623, 624 ... Separator 623p ... Hydrogen gas flow path 624p ... Water flow path

Claims (3)

[Claims] 1. A humidifying device for humidifying a fuel gas supplied to an electrode of a fuel cell, wherein the humidifier is in contact with a water flow path and the fuel gas flow path, and responds to a pressure difference between the water and the fuel gas. And a water-permeable porous membrane, and a fuel cell humidifier provided with a catalyst on at least one of the inside of the porous membrane and the surface of the water on the flow channel side. 2. A humidifying device for humidifying a fuel gas supplied to an electrode of a fuel cell, wherein the humidifier is in contact with a water flow path and the fuel gas flow path, and responds to a pressure difference between the water and the fuel gas. A humidifier for a fuel cell, which comprises a porous membrane that allows water to permeate therethrough and which has a support having water permeability and carrying a catalyst provided in the water flow path. 3. A humidifying device for humidifying a material gas supplied to an electrode of a fuel cell, the humidifier being in contact with a storage passage for storing water and a flow path of the material gas, and for reducing a pressure difference between the water and the material gas. A porous membrane permeable to the water, a gas amount detection means for detecting the amount of gas retained in the water storage passage, a gas vent passage for exhausting the retained gas from the storage passage, A humidifier for a fuel cell, comprising: an on-off valve that opens and closes a gas vent passage; and a control unit that controls the opening and closing of the on-off valve according to the amount of gas detected by the gas amount detection unit.