KR100823205B1 - Dilluted fuel mixing tank for direct methanol fuel cell - Google Patents

Abstract

A diluted fuel mixing tank for a direct methanol fuel cell is provided to minimize the capacity of a fuel tank, thereby reducing the size of a fuel cell system and maximizing the efficiency of fuel. A diluted fuel mixing tank comprises a lower bath(11) which has an upward open type lower space(R1), is provided with a first injection hole(I1) for injecting the pure methanol of a pure methanol tank into the lower space and a second injection hole(I2) for injecting the fluid discharged from the one side of a fuel cell, and is provided with a first discharge hole(E1) formed at the position higher than the first and second injection holes for supplying the diluted fuel generated at the lower space to the fuel cell; a partition wall(12) which is combined with the total internal interference of the lower bath and has a water inflow hole and a gas inflow hole(H2) provided with a vertically erected gas pipe(P1); and an upper bath(13) which is extended from the upper part of the lower bath, has a downward open upper space(R2) divided with the lower space by the partition wall, and is provided with a third injection hole(I3) for injecting the water and air discharged from the other side of the fuel cell and a second discharge hole(E2) for discharging the excessive of water and carbon dioxide gas in fluid.

Description

Diluted fuel mixing tank for direct methanol fuel cell

1 is a perspective view of a mixing tank of a first embodiment of the present invention;

Figure 2 is a perspective view of the mixing tank of the first embodiment of the present invention.

3 is a perspective view of a mixing tank of a second embodiment of the present invention;

Figure 4 shows the diffuser that can be used in the mixing tank of the present invention,

  (A) is a perspective view of the ring-shaped tube,

  (B) is a perspective view of a straight diffuser.

5 is a perspective view of a mixing tank of a third embodiment of the present invention;

          ((Explanation of symbols for main part of drawing))

     11. Bottom tank 12. Bulkhead 13. Upper tank

     14. Valve member 15, 15 '. Diffuser 16. Terminal Sensor

     17. Water level sensor E1. First outlet E2. 2nd outlet

     G. Groove H1. Water Inlet H2. Gas inlet

     H3. Through I1. First inlet I2. 2nd entrance

     I3. Third inlet P1. Gas pipe P2. water tube

     R1. Subspace R2. Upper space

The present invention recovers excess methol and water discharged after being used in a direct methanol fuel cell (DMFC), and then mixes with pure methanol to supply a mixture of dilution fuel diluted for direct methanol fuel cells. A direct dilution fuel mixing tank for methanol fuel cells.

A fuel cell is a battery that directly converts chemical energy generated by oxidation of a fuel into electrical energy. It is the same as a conventional chemical cell in that it uses an oxidation / reduction reaction, but it is different from a chemical cell that reacts in a closed system. Alternatively, the reaction product acts as a power generation unit where the reactants are continuously supplied externally while the reaction products are continuously discharged out of the system.

The most representative ones are hydrogen-oxygen fuel cells, all of which use alkaline aqueous solution as electrolyte and pure hydrogen and oxygen as reactants.

The fuel cell using alkaline electrolyte as the first generation, the high-temperature molten carbonate fuel cell without the noble metal catalyst is the second generation, and the solid electrolyte fuel cell capable of generating higher efficiency is the third generation fuel. It is called a battery, and the closest practical use is a phosphate fuel cell using a phosphate electrolyte as the first generation fuel cell.

The fuel cell is a hydrogen-air fuel cell using hydrogen gas mainly containing hydrogen reformed fossil fuel and oxygen in the air, and has excellent energy conversion efficiency, no pollution factor, and can replace conventional thermal power generation. Therefore, development research for commercialization is rapidly progressing.

However, a fuel cell using hydrogen has a difficulty in handling hydrogen, and when using a liquid fuel such as methanol, there is a problem in that an additional facility is required, such as a reforming apparatus for generating hydrogen therefrom. For example, it is possible to develop a power plant of a certain size or more, but miniaturization is impossible or very difficult.

Therefore, a direct methanol fuel cell has been developed that can use liquid methanol directly as a fuel. The direct methanol fuel cell has a structure in which an anode and a cathode are coupled to both sides of the polymer electrolyte membrane, and toward the cathode side. The supplied methanol and water react to generate hydrogen ions and electrons, and the generated hydrogen ions and electrons move to the anode side through the electrolyte membrane and the external circuit, respectively, and then hydrogen ions and electrons combine with oxygen to generate water. Through the electrical energy is generated.

The direct methanol fuel cell as described above has recently been intensively developed as a portable battery because it is relatively safe because it uses methanol as a liquid fuel rather than a gas, and can be made smaller and lighter.

That is, the direct methanol fuel cell has been evaluated as the most suitable fuel cell for miniaturization because it has a relatively low operating temperature of about 150 ° C. and uses liquid chain methanol directly as a fuel. There are disadvantages.

The crossover is a phenomenon in which only hydrogen ions generated at the cathode move through the electrolyte membrane to the anode, but methanol itself moves through the electrolyte membrane to the anode side due to the functional limitations of the current polymer electrolyte membrane. The introduced methanol reacts with the platinum catalyst of the anode to primarily reduce the electrochemical potential, thereby lowering the power generation efficiency, and also generate heat to cause combustion of the platinum catalyst, thereby losing the function of the fuel cell.

Therefore, in a direct methanol fuel cell, crossover of methanol is one of the most important problems to be solved. In order to prevent this, a new electrolyte membrane has to be developed. Currently, the surface of the polymer electrolyte membrane is modified to reduce the permeability of methanol. Alternatively, a method of diluting to about 3 wt% without using pure methanol as a fuel is used.

However, when using a diluted fuel diluted with methanol as described above, for example, when one liter of pure methanol is required, the diluted fuel becomes about 33 liters, which is more diluted than when using pure methanol. The capacity of the fuel tank for storing and using the fuel becomes larger than necessary, and the dilution fuel supplied to the fuel cell does not completely react and is discharged together with water, thereby lowering the efficiency of using methanol.

In other words, the fuel supply method of the conventional direct methanol fuel cell is not only a large dilution fuel tank for storing and supplying the methanol diluted in advance, but also a non-circulating non-reacted methanol that is not reacted in the fuel cell with water. Since it is a formula, there is a fundamental difficulty in miniaturization, and there is also a problem of low use efficiency of fuel.

The present invention was devised to solve the problem of miniaturization of a fuel cell system using dilute fuel diluted with methanol in water to directly operate a methanol fuel cell, and to remove unreacted methanol and water discharged from a fuel cell. According to the recovered and unreacted methanol, the pure methanol is diluted and then supplied to the fuel cell by appropriately mixing pure methanol with a mixture of unreacted methanol and water. It is an object of the present invention to provide a dilution fuel mixing tank for direct methanol fuel cells that can significantly reduce the capacity of the fuel tank and maximize the use efficiency of methanol by recovering unreacted methanol and circulating it repeatedly. have.

The above object of the present invention is a double tank structure in which the inner space is divided by a partition wall and divided into upper and lower basins each having an upper and lower space, a pair of inlets provided in the lower part of the lower tank, and an inlet above A discharge port provided on one side of the lower tank of, and the injection port and the discharge port is achieved by the upper tank provided respectively.

Dilution fuel mixing tank for direct methanol fuel cell of the present invention is a device for supplying diluted methanol used as fuel for direct methanol fuel cell (hereinafter referred to as "fuel cell"), and the unreacted surplus discharged from the fuel cell There is a technical feature of the present invention in mixing and diluting 100% pure methanol in methanol and water.

That is, the diluted fuel mixing tank of the present invention recovers excess methanol and water discharged after being used in a fuel cell, and adjusts and mixes the amount of pure methanol according to the amount, concentration, etc. of the excess methanol mixed with water. It is a device for supplying a diluent fuel mixed with excess methanol, pure methanol and water to a fuel cell.

Dilution fuel mixing tank of the present invention serves as described above, the inner partition is divided into an upper tank and a lower tank, the upper and lower tanks are connected to each other by a water inlet hole and a gas inlet hole formed through the partition wall.

In addition, the lower tank of the mixing tank is connected to a pure methanol tank to receive a first inlet for supplying pure metalol from the pure methanol tank, and to one side of the fuel cell to receive excess methanol, water, and carbon dioxide gas from the fuel cell. And a second inlet for supplying the diluted fuel mixed and diluted in the lower tank to the fuel cell, respectively. Hereinafter, both the excess methanol and water and carbon dioxide gas discharged from one side of the fuel cell will be referred to as "fluid".)

In addition, the upper tank of the mixing tank is connected to the other side of the fuel cell and the third inlet through which the air and water discharged from the fuel cell are injected, and the excess water, the air and the lower tank introduced through the gas inlet from the tank. As a structure having a second outlet for discharging carbon dioxide gas to the outside, a process in which pure methanol is diluted in a mixing tank of the present invention and then supplied to a fuel cell is as follows.

Pure methanol is injected from the pure methanol tank through the first inlet of the lower tank, and fluid is injected from the fuel cell through the second inlet, thereby diluting the pure methanol in the lower tank, and dilution generated in the lower tank. The fuel is supplied to the fuel cell through the first outlet of the lower tank, and the carbon dioxide gas introduced into the second inlet flows into the upper tank through the gas inlet hole of the partition wall and then is discharged to the outside of the mixing tank through the second outlet of the upper tank.

In addition, the water flowing into the third inlet of the upper tank from the other side of the fuel cell is supplied to the lower tank through the water inlet hole of the partition wall to be further used for diluting pure methanol, and the amount and concentration of the diluted fuel generated in the lower tank. Accordingly, when the amount of pure methanol is adjusted and water is supplied more than necessary, the water flowing into the third inlet of the upper tank is discharged to the outside of the mixing tank through the second outlet with carbon dioxide gas.

Therefore, it is preferable that a valve member capable of automatically opening and closing the water inlet hole is coupled to the water inlet hole formed in the partition wall. As the valve member, an automatic valve or a water level which is automatically operated by an electrical signal according to the water level of the lower tank. The float valve etc. equipped with the float which moves according to the example are mentioned as an example.

In addition, the gas inlet hole provided in the partition wall serves as a movement path in which carbon dioxide gas injected into the lower tank moves to the lower tank, and water introduced into the upper tank through the third inlet flows into the lower tank through the gas inlet hole. In order to prevent that from happening, it is preferable to couple a gas pipe having a hollow coincident with the gas inflow hole in the up and down directions to the upper tank side gas inflow hole, that is, the upper surface of the partition wall.

In addition, when the gas pipe is provided as described above, the upper end of the gas pipe must be made higher than the height of the second outlet port from the upper tank bottom, that is, the upper surface of the partition wall, and the water discharged into the third inlet port is discharged to the second outlet port. It will not flow into the basin through.

Details of the effects and the resulting effects, including the object and technical configuration of the present invention will be clearly understood by the following description with reference to the drawings showing a preferred embodiment of the present invention.

1 is a perspective view of the mixing tank of the present invention, Figure 2 is a cross-sectional view of the mixing tank of the present invention.

As shown in the mixing tank of the present invention,

The lower space R1 is upwardly open and discharged from one side of the first inlet I1 and a fuel cell (not shown) for injecting pure methanol from the pure methanol tank (not shown) into the lower space R1. Second inlets I2 for injecting fluid into the lower space R1 are respectively provided, and a first outlet E1 for supplying the dilution fuel mixed and produced in the lower space R1 to the fuel cell is provided. A lower jaw 11 provided at a position higher than the two inlets I1 and I2;

A plate-shaped partition wall 12 which is coupled to the entire inner diameter of the upper end of the lower tank 11 and has a gas inlet hole H2 having a water inlet hole H1 and an upright gas pipe P1 therethrough;

Water extending from the upper end of the lower tank 11, has a downward open upper space (R2) partitioned from the lower space (R1) of the lower tank 11 by the partition 12, the water discharged from the fuel cell And an upper tank 13 provided with a third inlet I3 through which air is introduced, and a second outlet E2 for discharging carbon dioxide gas, etc. introduced through excess water and air, and the gas pipe P1. It consists of.

At this time, the carbon dioxide gas introduced through the second inlet I2 of the lower tank 11 is discharged to the outside through the path of the gas inlet hole H2 → gas pipe P1 → second outlet E2, Water introduced through the third inlet I3 of the tank 13 flows into the lower tank 11 through the water inlet hole H1 of the partition 12 or outside the mixing tank through the second outlet E2. Is discharged.

Therefore, when the water inflow through the third inlet I3 is greater than the inflow into the lower tank 11 through the water inlet hole H1 or when the water inlet hole H1 is closed due to the situation of the lower tank 11, The water introduced into the third inlet I3 may be introduced into the lower tank 11 through the gas pipe P1. To prevent this, the height of the gas pipe P1 is higher than that of the second outlet E2. good.

Further, the height of the gas pipe P1 is higher than that of the ceiling surface of the upper tank 13, that is, the upper surface of the upper tank 13 at a position corresponding to the gas pipe P1 portion up and down is projected so that the cloth in the upper tank 13 It is also preferable to position the upper end of the gas pipe P1 in the groove G so that the downwardly open groove G is formed at the front side and the inner surface of the groove G does not come into contact with the gas pipe P1.

In this way, even when the level of water introduced into the upper tub 13 comes into contact with the ceiling surface inside the upper tub 13, the water surface of the water is caused by the gas pressure in the recess G to form the interior of the upper tub 13. As it does not rise any more through the water pipe (P1) is prevented from entering the water tank 13 through the lower portion (13).

Of course, depending on the pressure of the water flowing into the upper tank 13, the discharge pressure of the water through the second outlet (E2) and the pressure of the carbon dioxide gas may be caused some changes in the above phenomenon, groove (G) The forming of the gas pipe P1 may be more effective in preventing water from flowing into the lower tank 11 through the upper end of the gas pipe P1.

And, it is preferable that the water inlet hole (H1) of the partition 12 is automatically opened and closed by the valve member as needed, in order to combine the valve member, as shown in Figure 3, the water inlet hole (H1) ), That is, a water pipe (P2) having a hollow formed in the up and down direction coinciding with the water inlet hole H1 may be coupled to the bottom surface of the partition wall 12.

In addition, as the simplest structure of the valve member 14 for automatically opening and closing the water inlet hole H1, a float valve in which the float F and the valve V are combined may be exemplified.

In the mixing tank of the present invention configured as described above, it is preferable to mix pure methanol with excess methanol and water, and to mix them as uniformly as possible, and a power or non-powered stirrer (not shown) may be installed inside the lower tank 11. have.

In this case, the non-powered stirrer is a lift force of the stirrer that uses the floating force of the carbon dioxide gas introduced through the second inlet I2 of the lower tank 11 as the rotational power of the stirrer, that is, the carbon dioxide gas rising upward from the lower portion of the lower tank. By means of a stirrer with a rotary vane fan.

In addition, in order to uniformly mix methanol and water, as shown in FIG. 4, each of the first inlet I1 or the second inlet I2 has a plurality of through holes H3 in the lower part of the lower tank 11. It is also preferable to couple a pair of diffusers 15, 15 ′ connected to

That is, the pure methanol injected through the first inlet I1 and the fluid injected through the second inlet I2 are dispersed as much as possible into the lower tank 11 through the respective diffusers 15 and 15 '. By injecting in a stable state, the pure methanol and the fluid can be mixed more uniformly and quickly.

In order to dilute pure methanol in the lower tank 11, the methanol concentration and amount of the diluted fuel must be continuously determined, and thus, pure methanol and water must be supplied accordingly, so that the diluted fuel filled in the lower tank 11 is supplied. It is preferable to have a means for detecting the amount and concentration of, and there are various kinds of such means, looking at one example as follows.

As shown in FIG. 5, the metal terminal sensor 16 is coupled to the lower part of the lower tub 11, and is spaced apart from the terminal sensor 16, on the upper portion thereof, for example, a triangle, a trapezoid, or the like. Dilution fuel is provided by a plate-shaped metal level sensor 17 whose width is changed and a cross-sectional area is changed, and a controller 18 electrically connected to the terminal sensor 16 and the level sensor 17 is provided outside the mixing tank. Through the controller 18, the pure methanol supply amount, the dilution fuel supply amount to the fuel cell, etc. can be controlled according to the concentration and the amount of.

That is, the diluted fuel serves as a conductor connecting the terminal sensor 16 and the water level sensor 17, and the resistance value of the water level sensor 17 that changes according to the water level becomes an electric signal. The amount, concentration, pure methanol injection amount, dilution fuel supply amount, etc. of the dilution fuel are controlled.

At this time, various fluids injected or discharged into the mixing tank are made by a pump, and the controller 18 controls each pump by signals from the terminal sensor 16 and the water level sensor 17. In the piping for supply, etc., various pumps and valves are essential components that must be naturally combined, and the description thereof is omitted for convenience.

As described above, the dilute fuel mixing tank for direct methanol fuel cell of the present invention uses dilute methanol beforehand since pure methanol is diluted with unreacted methanol and water recovered from the fuel cell immediately before fuel cell input. Fuel tank system can be miniaturized by minimizing the capacity of the fuel tank compared to the fuel tank in this case, and maximized the efficiency of use of fuel because unreacted methanol that is not reacted in the fuel cell is continuously circulated and used. There is this.

Claims (5)

It has an upward open lower space (R1), the first inlet (I1) for injecting pure methanol of the pure methanol tank into the lower space (R1) and the second inlet (I2) for injecting fluid discharged from one side of the fuel cell ), Each of which is provided with a lower tank having a first discharge port E1 for supplying the dilution fuel mixed in the lower space R1 to the fuel cell at a position higher than the first and second injection ports I1 and I2. (11); A partition wall 12 coupled to the entire inner diameter of the upper end of the lower tank 11 and having a gas inlet hole H2 having a water inlet hole H1 and an upright gas pipe P1 therethrough; It is formed at the upper end of the lower tank 11, has a downward open upper space (R2) partitioned from the lower space (R1) by the partition 12, the water and air discharged from the other side of the fuel cell flows in Dilution fuel mixture for direct methanol fuel cell, characterized in that it comprises a third inlet (I3) and the upper tank 13, each provided with a second outlet (E2) for discharging excess carbon dioxide gas in the water and fluid. Tank. The method of claim 1, Dilute fuel mixing tank for direct methanol fuel cell, characterized in that the height of the gas pipe (P1) is higher than the second outlet (E2). The method of claim 1, Dilute fuel mixing tank for direct methanol fuel cell, characterized in that the bottom surface of the partition 12 is a water pipe (P2) having a hollow corresponding to the water inlet hole (H1) is erectly coupled. The method of claim 1, In the lower part of the lower tank 11, a pair of diffusers 15 and 15 ′ having a plurality of through holes H3 and connected to the first inlet I1 or the second inlet I2, respectively, are additionally provided. Dilution fuel mixing tank for direct methanol fuel cell, characterized in that coupled to. The method of claim 1, The lower tank 11 is coupled up and down so that the plate-shaped metal level sensor 17 and the metal terminal sensor 16 whose cross-sectional area is changed in width are not in contact, and the terminal sensor 16 and the water level sensor ( 17 is a dilution fuel mixing tank for direct methanol fuel cell, characterized in that it is electrically connected to a controller 18 outside the mixing tank.

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