KR101117635B1 - Fuel cell system - Google Patents

Abstract

Fuel cell system according to the present invention, at least one electricity generating unit for generating electrical energy through the electrochemical reaction of hydrogen and oxygen; A reformer for reforming the hydrogen-containing fuel to generate hydrogen gas, and supplying the hydrogen gas to the electricity generator; A fuel supply source for supplying the fuel to the reformer; An oxygen supply source supplying the oxygen to the electricity generator; And a concentration detecting unit connected to the hydrogen gas injector and configured to detect the concentration of the carbon monoxide through the color changing by reacting with the carbon monoxide contained in the hydrogen gas.

Fuel cell, stack, electricity generation unit, reformer, hydrogen gas, carbon monoxide, poisoning, concentration detection unit, body, concentration sensor, color, change

Description

Fuel Cell System {FUEL CELL SYSTEM}

1 is a schematic diagram showing an overall configuration of a fuel cell system according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view illustrating the stack structure shown in FIG. 1.

FIG. 3 is an exploded perspective view of the separator shown in FIG. 2 in which one side of the separator is rotated. FIG.

FIG. 4 is a partial cross-sectional view of a state in which the membrane-electrode assembly and the separator illustrated in FIG. 2 are assembled.

FIG. 5 is a schematic perspective view of the concentration sensor shown in FIG. 1.

6 is a perspective view illustrating a package structure of a fuel cell system according to an exemplary embodiment of the present invention.

The present invention relates to a fuel cell system, and more particularly, to a structure for detecting the concentration of carbon monoxide for a fuel cell.

As is known, a fuel cell is a power generation system that converts chemical reaction energy of hydrogen and oxygen contained in hydrocarbon-based materials such as methanol, ethanol and natural gas directly into electrical energy.

This fuel cell is classified into a phosphoric acid fuel cell, a molten carbonate fuel cell, a solid oxide fuel cell, a polymer electrolyte type or an alkaline fuel cell according to the type of electrolyte used. Each of these fuel cells operates on essentially the same principle, but differs in the type of fuel used, operating temperature, catalyst, and electrolyte.

Among these, the polymer electrolyte fuel cell (PEMFC, hereinafter referred to as PEMFC for convenience), which has been developed recently, has excellent output characteristics, low operating temperature, and fast start-up and response characteristics compared to other fuel cells. In addition to mobile power supplies such as automobiles, as well as distributed power supplies such as homes and public buildings and small power supplies such as for electronic devices has a wide range of applications.

Such a PEMFC basically includes a stack, a reformer, a fuel tank, a fuel pump, and the like to constitute a system. The stack forms the body of the fuel cell, and the fuel pump supplies the fuel in the fuel tank to the reformer. The reformer reforms the fuel to generate hydrogen gas and supplies the hydrogen gas to the stack. The PEMFC thus feeds the fuel in the fuel tank to the reformer by operation of a fuel pump, reforming the fuel in the reformer to generate hydrogen gas, and electrochemically reacting this hydrogen gas and oxygen in the stack to generate electrical energy. Let's do it.

By the way, in the conventional fuel cell system, the reformer described above is difficult to completely perform a chemical catalytic reaction for removing carbon monoxide, and generates hydrogen gas containing a small amount of carbon monoxide. Therefore, when the hydrogen gas is supplied to the anode electrode of the membrane-electrode assembly, the catalyst poisoning of the anode electrode by the carbon monoxide weakens the activity of the catalyst, resulting in deterioration of the performance of the fuel cell and shortening the life of the fuel cell. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a fuel cell system capable of easily detecting the concentration of carbon monoxide so as to prevent catalyst poisoning of the fuel cell by carbon monoxide in advance.

In order to achieve the above object, the fuel cell system according to the present invention includes at least one electricity generating unit for generating electrical energy through an electrochemical reaction between hydrogen and oxygen; A reformer for reforming the hydrogen-containing fuel to generate hydrogen gas, and supplying the hydrogen gas to the electricity generator; A fuel supply source for supplying the fuel to the reformer; An oxygen supply source supplying the oxygen to the electricity generator; And a concentration sensing unit connected to the injecting unit of the hydrogen gas to sense the concentration of the carbon monoxide through a color changing in response to the carbon monoxide contained in the hydrogen gas.

In the fuel cell system of the present invention, the fuel supply source comprises: a fuel tank for storing the fuel; And a fuel pump connected to the fuel tank and discharging the fuel stored in the fuel tank, wherein the fuel tank and the reformer may be connected by a first supply line.

In addition, the fuel cell system according to the present invention may include a plurality of electricity generating units, form a stack having a collection structure of these electricity generating units, and configure the reformer and the injection unit to be connected by a second supply line. .

In the fuel cell system of the present invention, the concentration detecting unit is provided on the second supply line.

In addition, the fuel cell system according to the present invention, the concentration detection unit, the body of the transparent pipe form of the both ends open; And a concentration sensor disposed in the main body in which a unique color changes according to the concentration of carbon monoxide contained in the hydrogen gas.

In addition, the fuel cell system according to the present invention includes a packaging portion in which the entire system is incorporated, and the packaging portion forms a hole for exposing the main body to the outside.

In addition, in the fuel cell system of the present invention, the oxygen supply source includes an air pump that sucks air and supplies the air to the electricity generation unit, and the air pump and the electricity generation unit may be connected by a third supply line. have.

In the fuel cell system according to the present invention, the electricity generating unit is formed of a close contact structure of a membrane-electrode assembly (MEA) and a separator disposed on both sides of the membrane-electrode assembly. The electrode assembly includes an anode electrode and a cathode electrode positioned at both sides of the electrolyte membrane at the center thereof, and the anode electrode is formed of at least one of Pt or Ru.

In the present invention having such a structure, the fuel cell system adopts a polymer electrolyte fuel cell (PEMFC) method.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

1 is a schematic diagram showing an overall configuration of a fuel cell system according to an embodiment of the present invention.

Referring to FIG. 1, the system 100 is a power supply system mounted on a portable electronic device such as a notebook PC or a mobile communication terminal device to supply power for driving the portable electronic device.

The fuel cell system 100 generates a hydrogen gas by reforming a fuel containing hydrogen, and generates a polymer electrolyte fuel cell that generates electric energy through an electrochemical reaction between the hydrogen gas and oxygen. ; PEMFC) method is adopted.

In the fuel cell system 100 according to the present invention, the fuel for generating electricity includes methanol, ethanol or natural gas.

However, the fuel described below is defined as a fuel consisting of a liquid phase for convenience.

In addition, the system 100 may use pure oxygen gas stored in a separate storage means as oxygen reacting with hydrogen contained in the fuel, or may use air containing oxygen as it is. However, the latter example is explained below.

The fuel cell system 100 basically generates at least one electricity generating unit 11 for generating electrical energy through an electrochemical reaction between hydrogen and oxygen, and reforming a fuel containing hydrogen to generate hydrogen gas. A reformer 20 for supplying this hydrogen gas to the electricity generator 11, a fuel supply source 30 for supplying the fuel to the reformer 20, and an oxygen supply source for supplying oxygen to the electricity generator 10 ( 40).

The electricity generator 11 has a membrane-electrode assembly (MEA) (hereinafter referred to as 'MEA') 12 and a separator (bipolar plate in the art) on both sides thereof. (Bipolar Plate) ') refers to a fuel cell of a minimum unit that generates electricity by placing (14, 15). Therefore, the stack 10 of the stacked structure as in the present embodiment may be formed by sequentially stacking the plurality of electricity generating units 11 as described above.

The reformer 20 has a structure of a conventional reformer that generates hydrogen gas from a fuel containing hydrogen through a chemical catalytic reaction by thermal energy and reduces the concentration of carbon monoxide contained in the hydrogen gas. In detail, the reformer 20 generates hydrogen gas from the fuel through a catalytic reaction such as steam reforming, partial oxidation, or autothermal reaction. As an example, the reformer 20 reduces the concentration of carbon monoxide contained in the hydrogen gas by a method such as a catalytic gas conversion method, a selective oxidation method, or purification of hydrogen using a separator.

The fuel source 30 includes a fuel tank 31 for storing fuel as described above, and a fuel pump 33 connected to the fuel tank 31 for discharging the fuel stored in the fuel tank 31. do. At this time, the fuel tank 31 and the reformer 20 may be connected by a first supply line 91 in the form of a pipe.

The oxygen source 40 includes an air pump 41 capable of sucking air with a predetermined pumping force and supplying the air to the electricity generating unit 11 of the stack 10. Alternatively, the oxygen source 40 may be a known technology fan that can be mounted to a portable electronic device employing the system 100.

The stack 10 generating electricity by receiving hydrogen gas and air from the reformer 20 and the oxygen source 40 will be described with reference to FIG. 2.

FIG. 2 is an exploded perspective view illustrating the stack structure shown in FIG. 1.

1 and 2, the stack 10 applied to the present system 100 is an assembly of the electricity generating units 11 formed by closely placing the plurality of electricity generating units 11 as described above. The outermost of the stack 10 may be a pressing plate 13 for pressing and contacting the plurality of electricity generating units 11 described above. However, the stack 10 according to the present invention may be configured such that the separators 14 and 15 positioned at the outermost side of the stack 10 take the role of the pressure plate, excluding the pressure plate 13 described above. . In addition, the pressure plate 13 may be configured to have a unique function of the separators 14 and 15 which will be further described later, in addition to the function of press-contacting the plurality of electricity generating units 11.

In addition, the pressurizing plate 13 is supplied from the air supply source 40 and the first injection unit 13a for injecting hydrogen gas generated from the reformer 20 into the electricity generation unit 11 through the separator 14. The second injection portion 13b for injecting the air into the electricity generation unit 11 through the separator 14 and the first discharge portion 13c for discharging the remaining hydrogen gas after reacting in the electricity generation unit 11. ) And a second discharge portion 13d for discharging the water and the unreacted air generated by the hydrogen-oxygen combined reaction in the electricity generating portion 11. At this time, the first injection unit 13a and the reformer 20 are installed by a second supply line 92 in the form of a pipe, and the second injection unit 13b and the air pump 41 are in the form of a pipe. It may be connected by the third supply line 93.

FIG. 3 is an exploded perspective view of a state in which one side of the separator shown in FIG. 2 is rotated, and FIG. 4 is a partial cross-sectional view of the state in which the membrane-electrode assembly and the separator shown in FIG. 2 are assembled.

Referring to FIGS. 3 and 4, the membrane-electrode assembly 12 described above includes an anode electrode 17 and a cathode electrode 18 positioned on both sides thereof with an electrolyte membrane 16 interposed therebetween. It is composed. The separators 14 and 15 are closely arranged with the membrane-electrode assembly 12 interposed therebetween to form the hydrogen passage 19a and the air passage 19b on both sides of the membrane-electrode assembly 12. At this time, the hydrogen passage 19a is positioned on the anode electrode 17 side of the membrane-electrode assembly 12, and the air passage 19b is positioned on the cathode electrode 18 side of the membrane-electrode assembly 12. .

The anode electrode 17 is a portion to which hydrogen gas is supplied through the hydrogen passage 19a of the separator 14 on one side, and the catalyst layer 17a converts hydrogen gas into electrons and hydrogen ions, and the hydrogen It is composed of a gas diffusion layer (GDS) 17b for smoothly moving gas to the catalyst layer 17a. At this time, the catalyst layer 17a of the anode electrode 17 is made of Pt or an alloy of Pt and Ru having poisoning resistance of carbon monoxide.

In addition, the cathode electrode 18 is a portion in which air is supplied through the air passage 19b of the other separator 15, and a catalyst layer 18a for reducing and converting oxygen in the air into electrons and oxygen ions, and the oxygen Is composed of a gas diffusion layer 18b for smoothly moving to the catalyst layer 18a.

The electrolyte membrane 16 is formed of a solid polymer electrolyte having a thickness of 50 to 200 µm, and moves hydrogen ions generated in the catalyst layer 17a of the anode electrode 17 to the catalyst layer 18a of the cathode electrode 18, It combines with the oxygen ions of the cathode electrode 18 to enable ion exchange to produce water.

The electricity generation unit 11 of the stack 10 receives hydrogen gas generated from the reformer 20 when the fuel cell system 100 according to the present invention is configured as described above through the hydrogen passage 19a of the one side separator 14. When the air is supplied from the air pump 41 to the electricity generator 11 through the air passage 19b of the other separator 15, the electricity generator 11 generates hydrogen. The electrochemical reaction between and oxygen generates electricity, water and heat.

At this time, the hydrogen gas generated through the reformer 20 contains carbon monoxide as a side product. When such hydrogen gas is supplied to the anode electrode 17 of the membrane-electrode assembly 12, the catalyst layer 17a of the anode electrode 17 is poisoned by carbon monoxide to weaken the activity of the catalyst and consequently generate electricity. The performance and life of the unit 11 is shortened.

Therefore, according to the embodiment of the present invention, in the process of supplying the hydrogen gas generated from the reformer 20 to the electricity generating unit 11 of the stack 10, the color changing by reacting with the carbon monoxide contained in the hydrogen gas It includes a concentration detection unit 60 through which the user can detect the concentration of the carbon monoxide.

FIG. 5 is a schematic perspective view of the concentration sensor shown in FIG. 1.

1 and 5, the concentration detecting unit 60 according to the present embodiment is on the second supply line 92 connecting the reformer 20 and the first injection unit 13a of the stack 10. Is installed. Alternatively, the concentration detecting unit 60 is not limited to being installed on the second supply line 92, but is installed at a connection portion connecting the second supply line 92 and the first injection unit 13a. May be

Specifically, the concentration detection unit 60 has been developed by the US Department of Energy's Lawrence Berkeley National Laboratory (LBNL) and the US Quantum Group Incorporated (QGI, San Diego). Adopts carbon monoxide detection and monitoring system.                     

The concentration detecting unit 60 has a main body 61 in the form of a transparent tube substantially open at both ends, and is disposed in the main body 61 so that a unique color changes according to the concentration of carbon monoxide contained in the hydrogen gas. The concentration sensor 62 is provided.

The main body 61 has a rectangular transparent pipe shape, and has a structure that enables the flow of hydrogen gas supplied from the reformer 20 to the first injection portion 13a of the stack 10. Preferably, the body 61 is made of polystyrene. The main body 61 forms an inlet 61a at one end and an outlet 61b at the other end. At this time, a second supply line 92 is connected to the inlet 61a and the outlet 61b.

The concentration sensor 62 is disposed inside the main body 61, and reacts with the carbon monoxide contained in the hydrogen gas flowing along the main body 61 so that the first unique color is proportional to the amount of the carbon monoxide at least. It is configured to change to one different color. Preferably, the concentration sensor 62 takes the form of a sheet made of palladium and molybdenum, and is attached to an inner circumferential surface of the main body 61.

6 is a perspective view illustrating a package structure of a fuel cell system according to an exemplary embodiment of the present invention, in which the fuel cell system 100 (FIG. 1) having the above-described structure is provided in a box-shaped packaging unit 70. Can be mounted. The packaging unit 70 is provided to be detachable from the portable electronic device by known coupling means (not shown).

In addition, the packaging part 70 is provided with an exposure hole 71 for exposing the main body 61 of the concentration detecting unit 60 according to the present embodiment to the outside. Accordingly, the main body 61 is partially exposed to the outside through the exposure hole 71 of the packaging part 70. Since the main body 61 is made of a transparent material, the concentration sensor 62 disposed inside the main body 61 is exposed to the outside through the main body 61, so that the color of the concentration sensor 62 is caused by carbon monoxide. This is to visualize the change to the user.

Referring to the operation of the fuel cell system according to an embodiment of the present invention configured as described above in detail as follows.

First, in a state in which the packaging unit 50 incorporating the present system is mounted in a portable electronic device, the fuel pump 33 is operated to reform fuel stored in the fuel tank 31 through the first supply line 91. Supply to (20). Then, the reformer 20 generates hydrogen gas from the fuel through steam reforming (SR) catalytic reaction by thermal energy, and a water-gas shift reaction (WGS) catalytic reaction. Alternatively, the concentration of carbon monoxide contained in the hydrogen gas may be reduced through a selective oxidation (PROX) catalytic reaction. At this time, the hydrogen gas contains a small amount of carbon monoxide because it is difficult to completely perform the above series of catalytic reactions.

Subsequently, the hydrogen gas is supplied to the first injection part 13a of the stack 10 through the second supply line 92.

In this process, the hydrogen gas passes through the main body 61 of the concentration sensor 60. The concentration sensor 62 then reacts with the carbon monoxide contained in this hydrogen gas to change from its original color to another color depending on the amount of carbon monoxide. At this time, since the main body 61 is made of a transparent material and is exposed to the exposure hole 71 of the packaging part 70, the above-described concentration sensor 62 is exposed to the outside through the main body 61 so that the user Make the color aware of the change.

Thereafter, when the degree of discoloration of the concentration sensor 62 is measured by a conventional spectrophotometer, the concentration of carbon monoxide contained in the hydrogen gas can be known. The color change of the concentration sensor 62 allows the user to recognize the carbon monoxide concentration in the allowable range or the carbon monoxide concentration exceeding the allowable range without the poisoning risk of the electricity generating unit 11 according to the degree of discoloration.

As a result, the carbon monoxide concentration in the hydrogen gas supplied from the reformer 20 to the stack 10 can be measured in the same manner as described above, so that poisoning of the electricity generating unit 11 due to carbon monoxide can be prevented in advance. That is, when the concentration of the carbon monoxide exceeds the allowable range, the user recognizes this through the discoloration degree of the concentration sensor 62, and stops the operation of the system 100 to determine the concentration of the carbon monoxide contained in the hydrogen gas. Can be reduced. On the contrary, when the concentration of the carbon monoxide does not exceed the allowable range, the user recognizes this through the degree of discoloration of the concentration sensor 62, and the hydrogen gas passes through the second supply line 92 to the stack 10. It is made to continuously supply to the 1st injection part 13a.

In this state, the air pump 41 is operated to supply air to the second inlet 13b of the stack 10 through the third supply line 93.                     

Accordingly, the hydrogen gas is supplied to the anode electrode 17 of the membrane-electrode assembly 12 through the hydrogen passage 19a of the separator 14, and air is supplied through the air passage 19b of the separator 15. Supplied to the cathode electrode 18 of the electrode assembly 12. At this time, since the catalyst layer 17a of the anode electrode 17 is made of Pt or an alloy of Pt and Ru, it is not poisoned by carbon monoxide contained in hydrogen gas.

Thus, in the catalyst layer 17a of the anode electrode 17, hydrogen gas is decomposed into electrons and protons (hydrogen ions) through an oxidation reaction. Then, protons are moved to the cathode electrode 18 through the electrolyte membrane 16, and electrons are not moved through the electrolyte membrane 16 and the cathode of the membrane-electrode assembly 12 neighboring through the separators 14 and 15. It is moved to the electrode 18, which generates a current by the flow of electrons. In addition, the catalyst layer 18a of the cathode electrode 18 generates heat and moisture through the reduction reaction of the transferred protons and oxygen.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the scope of the invention.

According to the fuel cell system according to the present invention, since it comprises a concentration detector for detecting the concentration of the carbon monoxide through the color changing in response to the carbon monoxide contained in the hydrogen gas supplied to the stack, The concentration can be detected in real time. Therefore, since poisoning of the fuel cell by carbon monoxide can be prevented in advance, it is possible to further improve the performance of the fuel cell and further extend the life of the fuel cell.

Claims (9)

At least one electricity generating unit generating electrical energy through an electrochemical reaction between hydrogen and oxygen; A reformer for reforming the hydrogen-containing fuel to generate hydrogen gas, and supplying the hydrogen gas to the electricity generator; A fuel supply source for supplying the fuel to the reformer; An oxygen supply source supplying the oxygen to the electricity generator; And It is connected to the injection portion of the hydrogen gas concentration detection unit that can detect the concentration of the carbon monoxide through the color changing in response to the carbon monoxide contained in the hydrogen gas Including, The reformer and the injection unit are connected by a second supply line, The concentration detector is installed on the second supply line, The concentration detector, A main body in the form of a transparent pipe with both ends open; And And a concentration sensor disposed in the main body, the concentration sensor having a unique color that changes according to the concentration of carbon monoxide contained in the hydrogen gas. The method of claim 1, The fuel supply source, A fuel tank for storing the fuel; And A fuel pump connected to the fuel tank to discharge fuel stored in the fuel tank; And a fuel tank and a reformer connected by a first supply line. The method of claim 1, A fuel cell system comprising a plurality of said electric generators, and forming a stack which consists of a collection structure of these electric generators. delete delete The method of claim 1, It has a packaging part for embedding the whole system, And the packaging part forms a hole for exposing the body to the outside. The method of claim 1, The oxygen source includes an air pump for sucking air and supplying the air to the electricity generating unit, The air pump and the electricity generating unit is connected to the fuel cell system by a third supply line. The method of claim 1, The electricity generating unit is made of a close contact structure of a membrane-electrode assembly (MEA) and a separator (Separator) disposed on both sides of the membrane-electrode assembly, The membrane-electrode assembly includes an anode electrode and a cathode electrode on both sides of the electrolyte membrane, And the anode electrode comprises a catalyst layer comprising at least one of Pt and Ru. The method of claim 1, The fuel cell system is a fuel cell system comprising a polymer electrolyte fuel cell (PEMFC) method.

Images