JPH06333583A - Solid polyelectrolyte fuel cell generating device - Google Patents

Abstract

PURPOSE:To provide a solid polyelectrolyte fuel cell generating device improved in the humidifying state to a reaction gas. CONSTITUTION:A solid polyelectrolyte fuel cell generating device 1 is provided with an oxidizing gas supplying system 4 having an oxidizing gas source 41 such as atmosphere; an oxidizing gas pressurizing device 42 such as air compressor; a humidifying device 43; and a cooler 44, instead of the oxidizing gas supplying system in a conventional solid polyelectrolyte fuel cell generating device. The air 41A supplied from the oxidizing agent gas source 41 is first supplied to the humidifying device 43, humidified by the cooling water 51A heated by a cooling body 23 in the humidifying device 43, and then sent to the air compressor 42, wherein it is compressed. The pressurized air 41A thermally insulated and compressed by the air compressor 42 is cooled to a temperature never exceeding at least the operating temperature of a solid polyelectrolyte fuel cell 2 by the cooler 4. The pressurized air 41A humidified and also cooled by the cooler 44 is supplied to an oxidizing agent electrode 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid polymer electrolyte fuel cell power generator, and relates to a structure of an oxidant gas supply system in which a method for humidifying an oxidant gas supplied to a solid polymer electrolyte fuel cell is improved. .

[0002]

2. Description of the Related Art As fuel cells, various types of fuel cells such as solid polymer electrolyte type, phosphoric acid type, molten carbonate type, and solid oxide type are known, depending on the type of electrolyte used therein. Among them, the solid polymer electrolyte fuel cell shows a low resistivity when it is saturated with a polymer resin membrane having a proton (hydrogen ion) exchange group in the molecule, and functions as a proton conductive electrolyte. It is the fuel cell used.

FIG. 3 is a side sectional view schematically showing a solid polymer electrolyte fuel cell unit cell in a developed state, and FIG. 4 is a fuel cell unit using the unit cell shown in FIG. It is a block diagram which showed the integrated body typically. FIG. 5 shows FIG.
FIG. 3 is a supply system diagram of a solid polymer electrolyte fuel cell power generator using the fuel cell cell assembly shown in FIG. First, FIG.
In the above, reference numeral 7 is a fuel battery cell including an electrolyte layer 7C, a fuel electrode (also serving as an anode electrode) 7A, and an oxidant electrode (also serving as a cathode electrode) 7B. The electrolyte layer 7C is made of a thin rectangular solid polymer electrolyte membrane (hereinafter, sometimes abbreviated as PE membrane). The fuel electrode 7B is an electrode that is closely stacked on one main surface of the PE film 7C and receives supply of a fuel gas (for example, hydrogen or a gas containing hydrogen at a high concentration). In addition, the oxidant electrode 7B is an electrode that is laminated in close contact with the other main surface of the PE film 7C and receives supply of an oxidant gas (for example, air). The outer surface side of the fuel electrode 7A is one side surface 7a of the fuel cell 7, and the outer surface side of the oxidant electrode 7B is the other side surface 7b of the fuel cell 7. The fuel electrode 7A and the oxidant electrode 7B both support the respective catalyst layers containing a catalyst active material, and support the catalyst layers, and the reaction gas (hereinafter, the fuel gas and the oxidant gas are collectively referred to as such. A porous electrode base material having a function as a current collector while supplying and discharging a). The catalyst layer is disposed on both main surfaces of the PE film 7C by hot pressing.

Further, 8A is made of a gas impermeable material and is arranged on one side surface 7a side of the fuel cell 7 to allow the fuel gas 31A to flow to one side thereof and to be consumed. Is a separator having a large number of gas circulation grooves 81A for discharging the fuel gas containing hydrogen. 8B is
A gas flow groove 8 which is arranged on the other side surface 7b of the fuel cell 7 and allows the oxidant gas 41A to flow therethrough and discharges the oxidant gas 41A containing unconsumed oxygen.
Like the separator 8A, it has a large number of 1B and is made of a material that does not allow gas to permeate. In the separator 8A, the side surface 8Aa in which the gas flow groove 81A is formed is in close contact with the side surface 7a of the fuel cell 7, and in the separator 8B, the side surface 8Ba in which the gas flow groove 81B is formed is the side surface of the fuel cell unit 7. The fuel cells 7 are arranged so as to be in close contact with the fuel cells 7b.

Further, 61 is a reaction gas 31 flowing through the gas flow grooves 81A and 81B of the separators 8A and 8B.
A and 41A are gas seal bodies that have a role of preventing leakage to the outside of the flow path, and separators 8A and
It is arranged in a space between the peripheral portion of 8B and the peripheral portion of the fuel cell unit 7. Since the voltage generated by one fuel battery cell 7 is as low as about 1 [V] or less, a large number of unit cells 6 having the above-mentioned configuration are inserted in each fuel battery cell 7 and this. Via the separators 8A and 8B,
It is generally configured as a fuel cell integrated body (hereinafter, may be abbreviated as a stack) connected in series with each other, and is generally put to practical use by increasing the voltage.

In FIG. 4, reference numeral 9 denotes a current collector plate 9 for stacking a plurality of unit cells 6 and for extracting DC electricity generated in the fuel cells 7 of the plurality of unit cells 6 at both ends thereof.
1a and 91b, the unit cell 6 and the current collectors 91a and 91b
Insulating plate 92 for electrically insulating the structure from the structure
a, 92b, single cells 6, current collectors 91a, 91b, and electrical insulation plates 92a, 92b.
Tightening bolt 94 that gives moderate pressure to a and 93b
In addition to these, in addition to these, it is a stack of the solid polymer electrolyte fuel cell which is constituted by a cooling body 95 inserted every time a plurality of unit cells 6 are stacked.

In the fuel cell unit 7, when generating direct current electricity, which will be described later, a loss equivalent to the amount of electric power generated is generated. The role of the cooling body 95 is to remove the heat due to this loss. Water (not shown) for removing heat is passed through the cooling body 95 to maintain the fuel cells 7 at an appropriate temperature described later. Therefore, in the stack 9 having the configuration shown in FIG. 4, the separators 8A and 8B are
The passage for the reaction gas to be supplied to the fuel cell 7 is ensured, and the direct current electricity generated by the fuel cell 7 is transmitted to the current collector plates 91a and 91b. It also plays the role of transferring the generated heat to the cooling body 95.

In this stack 9, a fuel gas is supplied to the fuel electrode 7A and an oxidant gas is supplied to the oxidant electrode 7B to each of the fuel electrode 7A and the oxidant electrode 7B included in the plurality of fuel cells 7. By doing so, the three-phase interface (the catalyst in the catalyst layer, the PE film, and one of the reaction gases are in contact with each other at the interface between the catalyst layer of each of the electrodes 7A and 7B and the electrolyte layer 7C made of the PE film. Interface), and direct current is generated by causing an electrochemical reaction. The catalyst layer is formed of a fine particle platinum catalyst and a fluororesin having water repellency, and by forming a large number of pores, the reaction gas is efficiently diffused up to the three-layer interface. Is maintained and a three-layer interface having a sufficiently large area is formed.

By the way, P forming the electrolyte layer 7C
As described above, the E membrane is a polymer membrane having a proton (hydrogen ion) exchange group in the molecule, and shows a resistivity of 20 [Ω · cm] or less at room temperature when it is saturated with water and exhibits a proton conductive electrolyte. It is a film that functions as. As this PE film, at present, a perfluorosulfonic acid resin film (for example, Nafion film manufactured by DuPont, USA) is known. The electrochemical reaction that occurs at the three-phase interface formed by the electrolyte layer 7C using such a PE film, the catalyst layer, and the reaction gas is as follows.

At the anode electrode 7A, the reaction of the formula (1) occurs.

[0011]

[Equation 1]

At the cathode electrode 7B, the reaction of the formula (2) occurs.

[0013]

[Equation 2]

That is, at the anode electrode 7A, hydrogen supplied from the outside produces protons and electrons. The generated protons pass through the PE film 7C into the cathode electrode 7
The electrons move toward B and move to the cathode electrode 7B through an external electric circuit (not shown). On the other hand, in the cathode electrode 7B, oxygen supplied from the outside reacts with the protons moving from the anode electrode 7A in the PE film 7C and the electrons moving from the external electric circuit to generate water. Thus, the fuel cell 7 obtains hydrogen and oxygen to generate direct current electricity. In such a solid polymer electrolyte fuel cell, in order to reduce the resistivity of the PE film 7C and obtain high power generation efficiency, a temperature condition of about 50 [° C.] to 100 [° C.] is usually used. Be driven in. Since the PE film 7C is also a film that does not allow the reaction gas such as the fuel gas and the oxidant gas to pass through, it also plays the role of preventing so-called cross leak in which the reaction gases are mixed with each other.

As described above, in order to keep the power generation efficiency of the solid polymer electrolyte fuel cell high, it is necessary to keep the water content of the PE membrane 7C saturated at the operating temperature. Further, the fuel gas 31A and the oxidant gas 41A are humidified, and the respective reaction gases are adjusted to a vapor pressure state close to saturation and supplied to the fuel cell.
In FIG. 5, 1A is a solid polymer electrolyte fuel cell 2
, Fuel gas supply system 3, and oxidant gas supply system 4A
And a cooling water system 5 is a solid polymer electrolyte fuel cell power generator. The solid polymer electrolyte fuel cell 2 is
It is provided with one or a plurality of stacks 9, and is schematically shown in FIG. 5 as including a fuel electrode 21, an oxidant electrode 22, and a cooling body 23.

The fuel gas supply system 3 supplies the fuel gas 31A to the fuel electrode 21, and the fuel gas source 31
And a humidifying device 32 and pipes 33, 34, 35, 36. The fuel gas 31A is from the fuel gas source 31 to the pipe 3
3 is supplied to the humidifying device 32, is humidified in the humidifying device 32, and then is supplied to the fuel electrode 21 through the pipe 34. The exhausted fuel gas containing hydrogen that has not been consumed in the fuel electrode 21 is partially exhausted from the pipe 35 to the outside of the solid polymer electrolyte fuel cell power generator 1A, but most of it is exhausted through the pipe 36. 34.

The oxidant gas supply system 4A includes an oxidant electrode 2
2, which supplies the oxidant gas 41A to the air source 2. The low-pressure oxidant gas source 41 such as the atmosphere, the oxidant gas pressurizing device 42 such as an air compressor, the humidifier 43, and the pipes 48a, 48.
b and 46 are provided. The oxidant gas 41A supplied from the oxidant gas source 41 is pressurized by the pressurizing device 42, supplied to the humidifying device 43 by the pipe 48a, humidified by the humidifying device 43, and then oxidized by the pipe 48b. It is supplied to the agent electrode 22. The exhausted oxidant gas in which oxygen is consumed in the oxidant electrode 22 is exhausted from the pipe 46 to the outside of the solid polymer electrolyte fuel cell power generator 1A.

The cooling water system 5 supplies cooling water 51A for removing heat due to loss generated during power generation reaction of the solid polymer electrolyte fuel cell 2 to the cooling body 23 and is heated by the cooling body 23. Humidification device 3 for cooling water 51A
2, 43, and a cooling water pump 51,
The pipe 52 is provided. The cooling water 51A is first pressurized by the cooling water pump 51 and then supplied to the cooling body 23 via the pipe 52 to cool the cooling body 23 to a predetermined temperature. Cooling water 5 heated by removing heat from the cooling body 23
1A is sequentially supplied to the humidifying device 32 and the humidifying device 43 through the pipe 52, and is used for humidifying the fuel gas 31A and the oxidant gas 41A as described above. As a result, the reaction gas 31A, 41A is substantially cooled by the cooling water 51.
Thus, it is possible to include the steam corresponding to the saturated steam pressure according to the temperature corresponding to the temperature A.

As the separator, in addition to the separators 8A and 8B having the above-mentioned groove 81A or groove 81B arranged on only one side surface, the grooves of the separators adjacent to each other in the stack structure are also integrally formed. By doing so, in order to rationalize the stack configuration, the grooves 81A, 8
There is also known a separator in which 1B is arranged on both side surfaces thereof.

[0020]

In the solid polymer electrolyte fuel cell power generator according to the prior art described above, the electrolyte layer 7C made of the PE film which constitutes the fuel cell 7 of the stack 9 is substantially the cooling water 51A. Although the fuel gas 31A and the oxidant gas 41A containing the steam corresponding to the saturated steam pressure corresponding to the temperature of 1 are humidified, the following problem still remains. That is, as described above, the cooling water 51A receives heat from the cooling body 23, and the cooling water 51A from the cooling body 23 also receives heat.
The heat given to the cooling water 51A is the heat loss generated in the fuel cell 7 transferred through the separators 8A, 8B, etc., so that the temperature of the cooling water 51A is higher than the operating temperature of the solid polymer electrolyte fuel cell 2. The temperature is always 5 to 10 [° C.], which is low. Therefore, even if the cooling water 51A is humidified, the reaction gas is not humidified to the saturated vapor pressure corresponding to the operating temperature of the fuel cell 2. In particular, when the operating temperature is high, the saturated vapor pressure changes greatly even if the temperature difference is small.
Due to the temperature difference from the operating temperature of, the degree of humidification of the reaction gas is greatly affected. As a result, the resistivity of the PE film 7C cannot be reduced sufficiently, which adversely affects the power generation characteristics of the solid polymer electrolyte fuel cell 2.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a solid polymer electrolyte fuel cell power generator in which the humidification state to a reaction gas is improved.

[0022]

The above-mentioned objects of the present invention are as follows: 1) a solid polymer electrolyte fuel cell, a fuel gas supply system for supplying a fuel gas to the solid polymer electrolyte fuel cell, and a solid fuel cell. A device comprising a fuel gas supply system for supplying an oxidant gas to a molecular electrolyte fuel cell, wherein the solid polymer electrolyte fuel cell uses a PE membrane as an electrolyte layer,
The fuel gas supply system includes a fuel battery cell that receives the supply of the fuel gas and the oxidant gas and generates DC power, and the fuel gas supply system includes a fuel gas supply device that supplies the fuel gas and a humidification device that humidifies the fuel gas. Further, the oxidant gas supply system is provided with an oxidant gas pressurizing device for pressurizing and supplying the oxidant gas, and a humidifying device for humidifying the oxidant gas, a solid polymer electrolyte type In the fuel cell power generation device, the oxidant gas supply system is achieved by arranging the humidifying device on the upstream side of the flow of the oxidant gas of the oxidant gas pressurizing device.

[0023]

According to the present invention, the oxidant gas supply system provided in the solid polymer electrolyte fuel cell power generator is provided with the humidifier on the upstream side of the flow of the oxidant gas of the oxidant gas pressurizer. Therefore, the humidification of the oxidizing gas is performed in a state where the oxidizing gas is not pressurized. By the way, as is well known, the saturated vapor pressure of a gas is related only to its temperature and not to its atmospheric pressure. Also, the partial pressure of water vapor cannot exceed the saturation pressure. From this, the water vapor partial pressure in the gas has the following properties.

When the gas temperature rises at a constant atmospheric pressure, the water vapor partial pressure increases, and when the gas temperature rises at a constant gas temperature, the water vapor partial pressure decreases. Therefore, even if the water vapor partial pressure of the oxidant gas in a low pressure state that is not pressurized is unsaturated, by pressurizing the oxidant gas in this state to a certain pressure or more, The water vapor pressure of the oxidant gas can be saturated.

By supplying the oxidant gas in such a saturated vapor pressure state to the fuel cell, it becomes possible to prevent the evaporation of water from the PE film.

[0026]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a supply system diagram of a solid polymer electrolyte fuel cell power generator according to an embodiment of the present invention. In FIG. 1, the same parts as those of the conventional solid polymer electrolyte fuel cell power generator shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, reference numeral 1 indicates that an oxidant gas supply system 4 is used in place of the oxidant gas supply system 4A in the conventional solid polymer electrolyte fuel cell power generator 1A shown in FIG. Is a solid polymer electrolyte fuel cell power generator. The oxidant gas supply system 4 includes an oxidant electrode 2
2, which supplies an oxidant gas 41A to the air 2, an oxidant gas source 41 such as the atmosphere, an oxidant gas pressurizing device 42 such as an air compressor, a humidifier 43, and pipes 45a, 45b, 45.
c, 45d and 46, and a cooler 44 installed as necessary. The oxidant gas 41A supplied from the oxidant gas source 41 is first supplied to the humidifier 43 through the pipe 45a, and after being humidified by the cooling water 51A heated in the cooling body 23 in the humidifier 43,
It is sent to the oxidant gas pressurizing device 42 through the pipe 45b and is pressurized. When the oxidant gas 41A is adiabatically compressed by the oxidant gas pressurizing device 42 and the temperature of the oxidant gas 41A excessively rises, the cooler 44 is provided and the pressurized oxidant gas 41A is provided.
A is sent to the cooler 44 through the pipe 45c and cooled to a temperature that does not exceed the operating temperature of the solid polymer electrolyte fuel cell 2 at least. The oxidant gas 41A that has been humidified and cooled by the cooler 44 is supplied to the oxidant electrode 22 through the pipe 45c.

Since the present invention has the above-mentioned structure, the oxidizing gas 41A is first humidified by the cooling water 51A.
Then, by being pressurized by the oxidant gas pressurizing device 42, the steam partial pressure can be lowered, so that the steam pressure can be saturated. As a result, even if the cooling water 51A having a low temperature is used as the humidification source, the water content of the PE membrane 7C included in the solid polymer electrolyte fuel cell 2 can be maintained in a saturated state.

In the above description of the embodiment, the oxidant gas supply system 4 is provided with the cooler 44. However, the present invention is not limited to this. For example, the oxidant gas pressurizing device 42 is adiabatically compressed. If the temperature rise that occurs is small, the cooling device 44 need not be installed.

[0030]

According to the present invention, with the above-mentioned structure, the oxidant gas is humidified to the saturated state, so that the water content of the PE membrane can be maintained in the saturated state. . As a result, the power generation characteristics of the fuel cell in the solid polymer electrolyte fuel cell power generator to which the present invention is applied are as shown in the graph of the power generation characteristics of the unit cell of FIG. There is an effect that it is possible to obtain high characteristics with respect to the power generation characteristics of.

[Brief description of drawings]

FIG. 1 is a supply system diagram of a solid polymer electrolyte fuel cell power generator according to an embodiment of the present invention.

FIG. 2 is a graph showing the power generation characteristics of a single cell in a solid polymer electrolyte fuel cell power generator to which the present invention is applied, in comparison with the case of a conventional example.

FIG. 3 is a side sectional view schematically showing a cell of a solid polymer electrolyte fuel cell in a developed state.

FIG. 4 is a configuration diagram schematically showing a fuel cell integrated body using the unit cell shown in FIG.

FIG. 5 is a supply system diagram of a solid polymer electrolyte fuel cell power generator using the fuel cell cell assembly shown in FIG.

[Explanation of symbols]

 1 Solid Polymer Electrolyte Fuel Cell Power Generation Device 2 Solid Polymer Electrolyte Fuel Cell 22 Oxidizer Electrode 23 Coolant 3 Fuel Gas Supply System 4 Oxidant Gas (Air) Supply System 41 Oxidant Gas (Air) Source 42 Oxidant Gas pressurizing device (air compressor) 43 Humidifying device 44 Cooler 51A Cooling water

Claims (1)

[Claims] 1. A solid polymer electrolyte fuel cell, a fuel gas supply system for supplying a fuel gas to the solid polymer electrolyte fuel cell, and a fuel gas for supplying an oxidant gas to the solid polymer electrolyte fuel cell. A solid polyelectrolyte fuel cell is a device including a supply system, wherein a solid polymer electrolyte membrane is used as an electrolyte layer, and a fuel cell that receives supply of a fuel gas and an oxidant gas and generates direct current power. The fuel gas supply system includes a fuel gas supply device for supplying the fuel gas, and a humidifying device for humidifying the fuel gas,
Further, the oxidant gas supply system includes an oxidant gas pressurizing device for pressurizing and supplying the oxidant gas, and a humidifying device for humidifying the oxidant gas, a solid polymer electrolyte fuel cell In the power generator, the oxidizing gas supply system has a humidifier installed upstream of the oxidizing gas pressurizing device in relation to the flow of the oxidizing gas.