KR20090117008A - Equipment for removing carbon dioxide for direct methanol fuel cell - Google Patents

Abstract

PURPOSE: An apparatus for removing carbon dioxide for a direct methanol fuel cell is provided to effectively discharge carbon dioxide generated during oxidation reaction of a fuel battery without a direction in which the fuel battery is placed. CONSTITUTION: An apparatus(200) for removing carbon dioxide for a direct methanol fuel cell comprises: a main body(201) which has hollows and a plurality of through holes(201b), wherein at least one side is opened and at least the other side may be opened or wholly blocked; a gas-liquid separator(210) which is arranged on the outer circumference of the main body to covers a plurality of through holes; and a mesh(220) arranged on the gas-liquid separator.

Description

Equipment for removing carbon dioxide for direct methanol fuel cell

The present invention relates to a carbon dioxide removal device for a direct methanol fuel cell, and more particularly, to a carbon dioxide removal device for a direct methanol fuel cell that can effectively discharge carbon dioxide generated during the oxidation reaction of the fuel cell regardless of the direction in which the fuel cell is placed. will be.

Recently, due to the rapid dissemination of portable electronic devices and wireless communication devices, a lot of interests and researches on the development of a fuel cell for power generation as a portable power supply and a clean energy source.

A fuel cell is a new power generation system that converts energy generated by electrochemical reaction between fuel gas (hydrogen or methanol) and oxidant (oxygen or air) directly into electrical energy.

Such fuel cells are classified into phosphoric acid fuel cells, molten carbonate fuel cells, solid oxide fuel cells, polymer electrolyte fuel cells, alkaline fuel cells, and direct methanol fuel cells, depending on the type of electrolyte used. Each of these fuel cells operates on essentially the same principle, but there are differences in the type of fuel used, operating temperature, catalyst, and electrolyte.

Among them, the direct methanol fuel cell (DMFC) uses methanol as a fuel, so it does not need to use a hydrogen reformer and can be operated at low temperature. In particular, the direct methanol fuel cell has a simpler fuel supply system and a simpler device than the other types of fuel cells, which can be miniaturized and more compact. Because of this, direct methanol fuel cell has the advantage that it can be applied to a wide range of applications, such as household, mobile equipment, portable power, military.

In such a direct liquid fuel cell, a direct methanol fuel cell using methanol and water as a mixed fuel is used as an electrode reaction by oxidizing a fuel (anode electrode reaction) and reducing hydrogen ions and oxygen. Reduction reaction (cathode electrode reaction) takes place. In the oxidation reaction, methanol and water react to generate carbon dioxide, hydrogen ions, and electrons, and the generated hydrogen ions are transferred to the cathode electrode through the electrolyte membrane. In the reduction reaction, hydrogen ions, electrons transferred through an external circuit, and oxygen supplied separately react to form water. Therefore, the overall reaction of the direct methanol fuel cell is a reaction in which methanol and oxygen react to generate water and carbon dioxide.

Meanwhile, the fuel cell may be classified into an active type and a passive type according to its configuration. The active type is a method of supplying and circulating methanol or air as fuel to a fuel cell using a pump or a fan, which is complicated in configuration but has an advantage of easily obtaining a large power. On the other hand, since the passive type supplies fuel and air to the fuel cell by using convection or concentration gradient without using a separate supply device, there is an advantage that the configuration is simple and is suitable for miniaturization. In addition, this passive type is operated at room temperature for mobile equipment and has less power than the active type.

1 is a view for explaining a fuel circulation and carbon dioxide removal process in a passive fuel cell system.

Referring to FIG. 1, a passive fuel cell system includes a membrane electrode assembly 100, current collectors 110a and 110b, a cathode plate 120, a fuel storage layer 130, and a carbon dioxide removal apparatus 200. do. The membrane electrode assembly 100 is composed of an electrolyte membrane 101 and a cathode electrode 102 and an anode electrode 103 disposed in close contact with both surfaces of the electrolyte membrane 101 with the electrolyte membrane 101 interposed therebetween. do.

Referring to Figure 1 describes the operation of the passive direct methanol fuel cell system as follows.

First, fuel is supplied from the fuel storage layer 130 to the anode electrode 103 through the anode current collector 110b. In the anode electrode 103, hydrogen ions, electrons, and carbon dioxide are generated by an oxidation reaction. The generated electrons are transferred to the cathode electrode 102 through an external circuit (not shown) through the current collectors 110a and 110b, and the anode electrode 103 is formed through the electrolyte membrane 101 at the cathode electrode 102. Water is generated by the reduction reaction in which the hydrogen ions migrated from the electrons and the electrons and oxygen meet.

The carbon dioxide generated at the anode electrode 103 is moved to the carbon dioxide removal device 200 together with the unreacted methanol solution, the carbon dioxide is discharged to the outside through a gas-liquid separator (not shown), and the methanol solution is stored in the fuel storage layer ( Go to 130) to continue circulation.

As described above, in the direct methanol fuel cell system, the performance of the system can be maintained only when the methanol solution is continuously supplied from the outside and the carbon dioxide generated is continuously removed. In addition, in order to be used as a portable or portable power source, a direct methanol fuel cell system must be configured in a completely sealed type, and a device for recovering and removing carbon dioxide generated by an oxidation reaction at the anode electrode is necessary.

In general, the carbon dioxide removal device is a gaseous carbon dioxide and a liquid methanol solution is introduced together and separated from each other through a built-in gas-liquid separator to be discharged through different paths, the conventional fuel cell system, that is, the carbon dioxide removal device is placed If the angle is inclined from a predetermined position, there is a problem in that it does not smoothly discharge the introduced carbon dioxide.

It is an object of the present invention to provide a direct methanol fuel cell carbon dioxide removal apparatus capable of effectively discharging carbon dioxide generated during an oxidation reaction regardless of the direction in which the fuel cell is placed.

The present invention to solve the above problems,

A main body having a hollow and at least a portion of one surface of which is open and at least a portion of the other surface of which is opened or the other surface of the other surface is closed and a plurality of through holes are formed on an outer circumferential surface thereof so as to communicate with the hollow;

A gas-liquid separation membrane disposed on an outer circumferential surface of the main body to cover the plurality of through holes; And

Provided is a carbon dioxide removal apparatus for a direct methanol fuel cell having a mesh disposed on the gas-liquid separator.

According to an embodiment of the present invention, the inlet and outlet are disposed on each of one side and the other side of the main body or on one side of the main body so as to communicate with the hollow.

According to another embodiment of the invention, the inner width of the inlet and the outlet is narrower than the width of the hollow.

According to another embodiment of the present invention, the gas-liquid separator is a porous membrane in which a plurality of pores are formed.

According to another embodiment of the invention, the pores of the gas-liquid separator has a diameter of 0.1 to 10㎛ size.

According to another embodiment of the present invention, the gas-liquid separator is a hydrophobic polymer membrane.

According to another embodiment of the invention, the body is cylindrical, triangular, rectangular, rectangular, triangular, rectangular, at least a portion of each of the corresponding two bottoms are open or at least a portion of one of the two bottoms is open and the other is entirely blocked. , Pentagonal, hexagonal, or octagonal.

In addition, the present invention to solve the above problems,

It provides a fuel cell having at least one carbon dioxide removal device according to any one of the above embodiments.

According to the present invention, a carbon dioxide removal device for a direct methanol fuel cell that can effectively discharge carbon dioxide generated during an oxidation reaction regardless of the direction in which the fuel cell is placed can be provided.

Next, a carbon dioxide removal apparatus for a direct methanol fuel cell according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of a direct carbon dioxide removal apparatus for a direct methanol fuel cell according to an embodiment of the present invention, FIG. 3 is a cross-sectional view taken along line AA ′ of FIG. 2, and FIG. 4 is a carbon dioxide removal apparatus of FIG. 2. Exposed only the main body is a perspective view showing, Figure 5 is a perspective view showing the carbon dioxide removal apparatus of FIG.

2 to 5, the carbon dioxide removal apparatus 200 according to an embodiment of the present invention includes a body 201, a gas-liquid separation membrane 210, and a mesh 220.

The main body 201 has a hollow, and at least a portion of one surface and at least a portion of the other surface are open, and a plurality of through holes 201a are formed on the outer circumferential surface so as to communicate with the hollow. Specifically, the main body 201 may be a cylindrical, triangular, rectangular, pentagonal, hexagonal, or octagonal, such that at least a portion of each of the two bottom surfaces is open. However, the present invention is not limited thereto, and although not shown here, the body is cylindrical, triangular, rectangular, pentagonal, at least a portion of which one of the two corresponding bottoms is open and the other bottom is closed. It may be a tubular shape, a hexagonal cylinder shape, an octagonal cylinder shape, or the like.

In addition, the outer circumferential surface of the main body 201 is formed so as to surround the main body 201 360 degrees around the main body groove 201b for accommodating the gas-liquid separation membrane 210 and the mesh 220 to be described later. However, the main body groove 201b is not necessarily required and may be omitted.

In addition, one side of the main body 201 is provided with an inlet 201c through which the carbon dioxide discharged from the fuel cell stack (not shown) and the unreacted methanol solution are introduced, and the methanol solution in which the carbon dioxide is removed is discharged. Outlet 201d is provided. However, if the body is formed of a cylindrical shape or the like and at least a portion of one of the two corresponding bottoms of the cylindrical body is open and the other bottom is completely blocked, the inlet and outlet are opened so as to communicate with the hollow. It may be installed only on one side.

In addition, the inner width W _201c of the inlet 201c and / or the outlet 201d is a hollow width W _h to secure a space where layer separation of the fuel, which is a liquid, and the gas, which is a gas, is facilitated. Narrower ones are preferred. Specifically, the inner width W _201c of the inlet 201c and / or the outlet 201d is preferably about 1 to 10 times smaller than the hollow width W _h .

The gas-liquid separation membrane 210 is disposed on the outer circumferential surface of the main body 201 to cover the plurality of through holes 201a as a membrane for selectively permeating carbon dioxide by suppressing the permeation of the methanol solution and smoothing the discharge of the carbon dioxide. Specifically, in the present embodiment, the gas-liquid separation membrane 210 is disposed on the outer circumferential surface of the main body 201 to be accommodated in the main body groove 201b. The gas-liquid separation membrane 210 is a porous membrane in which a plurality of pores are formed. In addition, the pores preferably have a diameter of 0.1 to 10㎛ size, more preferably have a diameter of 0.5 to 10㎛ size. If the pore diameter is less than 0.5 μm, carbon dioxide is not easily discharged, and thus the performance of the fuel cell may be degraded due to an increase in pressure. If the pore diameter exceeds 10 μm, the methanol solution may leak into the pore together with carbon dioxide. have.

In addition, the gas-liquid separation membrane 210 is preferably a hydrophobic polymer membrane. As the gas-liquid separator 210, polyvinylidene fluoride, fluoroethylene propylene, polytetrafluoroethylene, fluorinated ethylene propylene, polychlorotrifluoroethylene, and fluoroethylene polymer may be used.

The mesh 220 is disposed on the gas-liquid separator 210 to prevent damage to the gas-liquid separator 210 due to contact with an external object or an increase in the internal pressure of the apparatus 200. The size and thickness of the mesh 220 are not particularly limited as long as it can prevent damage of the gas-liquid separator 210, but the thickness of the mesh 220 is limited to a degree that can be completely accommodated in the body groove 201b. It is desirable to be.

Hereinafter, the operation and effects of the carbon dioxide removal device of the present invention will be described in detail with reference to FIGS. 2 to 5.

First, carbon dioxide and unreacted methanol solution discharged from a fuel cell stack (not shown) flow into the inlet 201c.

After inflow, the carbon dioxide is lower in density than the methanol solution regardless of the position where the carbon dioxide removal device 200 is placed, so that the carbon dioxide is moved in the opposite direction to the gravity direction and the methanol solution is moved in the gravity direction. However, since the gas-liquid separation membrane 210 is disposed to wrap the outer circumferential surface of the main body 201 360 degrees, at least a portion of the carbon dioxide removal apparatus 200 is in contact with carbon dioxide in any direction. Accordingly, the carbon dioxide may be smoothly discharged to the outside through the gas-liquid separator 210. Carbon dioxide emitted to the outside is released into the atmosphere as it is, or is introduced into a separate capture device.

Meanwhile, the introduced methanol solution is re-introduced into the fuel cell stack through the outlet 201d while carbon dioxide is removed.

The carbon dioxide removal apparatus having the above configuration is not particularly limited in size or number, and one is used alone or in consideration of carbon dioxide emission according to the power density required by the direct methanol fuel cell system employing the same. More than two may be used in series or in parallel.

The present invention will be described in detail with reference to the following Examples. However, the present invention is not limited only to the following examples.

Example

Example 1 Test of Power Density Change Over Time

The direct methanol fuel cell used a fuel cell system as shown in FIG. 1 connecting the carbon dioxide removal apparatus of FIG. 2. The membrane-electrode assembly 100 of the fuel cell was manufactured using a conventional method known in the art, a platinum-ruthenium alloy catalyst manufactured by Dongjin Semichem was used as an anode catalyst, and Dongjin Semichem was used as a cathode catalyst. The prepared platinum-cobalt catalyst was used. Dupont's Nafion 211 was used as the polymer electrolyte membrane 101. As the electrode support (not shown), SGL's 24AA (anode) and 24BC (cathode) were used, and the electrode area was 4.84 cm ² . A thermocompression process was performed at 110 ° C. for 3 minutes to prepare the membrane-electrode assembly 100. Porous polytetrafluoroethylene having a pore size of 3 μm in diameter was used as the gas-liquid separator, and the area of the prepared gas-liquid separator was 4 cm ² .

The fuel cell system was operated to measure a change in current density over time, and the results are shown graphically in FIG. 6. During the operation of the fuel cell system, a current of 700 mA was applied for 1 hour. In addition, the concentration of the methanol solution used was 2.5M and the on-off operation of the current was repeated every 10 minutes.

Referring to FIG. 6, it can be seen that power density was maintained substantially constant for 1 hour. In other words, it can be seen from the results that the performance of the fuel cell system was kept constant for 1 hour, which proves that carbon dioxide was smoothly discharged from the carbon dioxide removal device.

On the other hand, it was observed whether the leakage of the methanol solution through the gas-liquid separator, it was confirmed that such leakage does not occur.

Example 2 Change Test of Current Density According to the Area of Gas-Liquid Separation Membrane

In the fuel cell system as in Example 1, the size of the gas-liquid separator was sequentially increased to 4, 8, 12, and 16 cm ² , and the power density thereof was measured in the same manner as in Example 1, and the results are shown in FIG. 7. Shown graphically.

Referring to FIG. 7, it can be seen that as the area of the gas-liquid separator increases, the power density also increases in proportion to this. From this result, it can be seen that the emission of carbon dioxide increases as the area of the gas-liquid separator increases. Therefore, it is desirable to make the area of the gas-liquid separator as large as possible in the manufacture of the carbon dioxide removal apparatus.

Although the preferred embodiment according to the present invention has been described above with reference to the drawings, this is merely exemplary, and those skilled in the art can understand that various modifications and equivalent other embodiments are possible therefrom. There will be. Therefore, the protection scope of the present invention should be defined by the appended claims.

1 is a view for explaining a fuel circulation and carbon dioxide removal process in a passive fuel cell system.

2 is a cross-sectional view of a carbon dioxide removal apparatus for a direct methanol fuel cell according to an embodiment of the present invention.

3 is a cross-sectional view taken along line AA ′ of FIG. 2.

4 is a perspective view showing only the main body of the carbon dioxide removal apparatus of FIG.

5 is a perspective view illustrating the carbon dioxide removal apparatus of FIG. 2.

FIG. 6 is a graph showing a change in current density with time when a direct methanol fuel cell employing a carbon dioxide removal device having the configuration of FIG. 2 is operated.

FIG. 7 is a graph showing a change in current density according to the area of a gas-liquid separator when operating a direct methanol fuel cell employing a carbon dioxide removal device having the configuration of FIG. 2.

<Explanation of symbols for the main parts of the drawings>

100 membrane electrode assembly 101 polymer electrolyte membrane

102: cathode electrode 103: anode electrode

110a: cathode current collector 110b: anode current collector

120: cathode plate 130: fuel storage layer

200: carbon dioxide removal device 201: main body

201a: main body groove 201b: through hole

201c: inlet 201d: outlet

210: gas-liquid separator 220: mesh

Claims (8)

A main body having a hollow and at least a portion of one surface of which is open and at least a portion of the other surface of which is opened or the other surface of the other surface is closed and a plurality of through holes are formed on an outer circumferential surface thereof so as to communicate with the hollow; A gas-liquid separation membrane disposed on an outer circumferential surface of the main body to cover the plurality of through holes; And Carbon dioxide removal apparatus for a direct methanol fuel cell having a mesh disposed on the gas-liquid separator. The method of claim 1, And a carbon dioxide removal device further comprising an inlet and an outlet disposed on one surface and the other surface of the main body or on one surface of the main body so as to communicate with the hollow. The method of claim 2, The inner width of the inlet and the outlet is carbon dioxide removal device, characterized in that narrower than the width of the hollow. The method of claim 1, The gas-liquid separator is a carbon dioxide removal device, characterized in that the porous membrane is formed with a plurality of pores. The method of claim 4, wherein Pore of the gas-liquid separator is a carbon dioxide removal device, characterized in that having a diameter of 0.1 to 10㎛ size. The method of claim 1, The gas-liquid separator is a carbon dioxide removal device, characterized in that the hydrophobic polymer membrane. The method of claim 1, The body may have a cylindrical, triangular, rectangular, pentagonal, hexagonal, or octagonal cylinder, at least a portion of each of the two corresponding bottoms being opened or at least a portion of one of the bottoms being open and the other being entirely blocked. Carbon dioxide removal device, characterized in that the type. A fuel cell comprising at least one carbon dioxide removal device according to any one of claims 1 to 7.

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