KR20200072676A - Gas-liquid separator attached a connection tube for fuel level control for direct methanol fuel cell system and direct methanol fuel cell system comprising the same - Google Patents

Abstract

The present invention relates to a gas-liquid separator for a direct methanol fuel cell system having a connection tube for control of a fuel level, including: a separation plate embedded in the gas-liquid separator and vertically dividing an interior space of the gas-liquid separator into an upper chamber and a lower chamber; a water supply tube formed to pass through the separation plate, and an upper side of which is disposed in the upper chamber and a lower side of which is disposed in the lower chamber; and a connection tube for control of a fuel level that delivers gas filled in the lower chamber to the upper chamber and maintains the level of a methanol diluted fuel at a predetermined height, whereby the fuel can be maintained at the predetermined level even when the fuel cell system is inclined to one direction during an operation thereof, and a gas-liquid separation function can be smoothly continued. The present invention further relates to a direct methanol fuel cell system including the same.

Description

Gas-liquid separator for direct methanol fuel cell system with a water level maintenance connector and a direct methanol fuel cell system including the same. COMPRISING THE SAME}

The present invention relates to a gas-liquid separator for a direct methanol fuel cell system having a connection pipe for maintaining a water level and a direct methanol fuel cell system including the same, and more specifically, the fuel cell system is tilted in one direction during operation to incline the slope. Even if achieved, it is possible to maintain a constant water level, as well as a gas-liquid separator for a direct methanol fuel cell system having a water level separating connector for smoothly maintaining the water-liquid separation function and a direct methanol fuel cell system including the same.

A fuel cell is an electrochemical generator that directly converts chemical energy contained in gaseous hydrogen and hydrocarbon-based fuels such as natural gas or liquid methanol and ethanol into electrical energy and thermal energy.

Such an electrochemical fuel cell generator may function as a clean energy generator that can replace an internal combustion engine generator that uses fossil energy.

In addition, these electrochemical fuel cell generators can be configured as a fuel cell stack module in which a plurality of unit cells are stacked to control a wide range of outputs, and have a energy density of 4 to 10 times that of a conventional battery charger, so they are small and portable. It is attracting attention as a power source for buildings and automobiles.

Typical examples of a low temperature fuel cell operating at a temperature of 100° C. or lower are a polymer electrolyte fuel cell (PEMFC) and a direct methanol fuel cell (DMFC).

The direct methanol fuel cell uses liquid methanol directly as fuel, so it is easy to store, transport, and handle liquid fuel, and it is portable because of the advantages of simple system construction and low temperature operation, because a reformer or humidifier, which is essential in PEMFC, is unnecessary. And a mobile power supply.

The direct methanol fuel cell system is composed of a fuel supply unit, an air supply unit, and a cathode circulating water circulation unit, as well as a stack (composed of MEA, separation plate, gasket, and end plate), which is a core part of the power generation unit. It becomes a fuel cell power generation system.

The electrochemical reaction equation occurring at the electrodes constituting the direct methanol fuel cell stack is as follows.

CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e-

3/2O ₂ + 6H ⁺ + 6e- → 3H ₂ O

CH ₃ OH + 3/2O ₂ → 3H ₂ O + CO ₂ (E = 1.21V)

The anode reaction of methanol and water to the catalytic oxidation reaction of carbon dioxide (CO _2), hydrogen ion (proton, H ⁺⁾ and electron (e ^-) is generated.

In the cathode reaction, oxygen in the air generates oxygen ions (O ^2- ) through a catalytic reduction reaction, and reacts with hydrogen ions (H ⁺ ) that have passed through the electrolyte at the anode to produce water (H ₂ O).

The overall electrochemical reaction scheme is methanol (CH ₃ OH) and oxygen (O ₂₎ e (e ^-) respectively, oxidation and the reduction reaction generate water (H ₂ O) and carbon dioxide (CO _2), and through an external circuit By moving, electricity is obtained.

In the actual fuel cell electrode reaction, the methanol permeability of the cation conducting membrane used as an electrolyte becomes too high when a high concentration of methanol fuel is used, so the performance of the fuel cell is lowered. shall.

That is, if the methanol concentration in the fuel is too high, the amount of methanol permeated to the cathode increases, and these methanol burns at the cathode, resulting in a large amount of heat and methanol loss.

In other words, in order to supply 2-5 wt% of fuel to the stack, a tank for mixing fuel and product water, a gas-liquid separator, and a stock methanol tank are required, among which a tank for mixing fuel and product water and a gas-liquid separator are used for fuel. They occupy the largest volume in the battery system, and they are connected and integrated with each other to reduce the overall volume of the system.

When the direct methanol fuel cell system is operated for the first time, pure methanol is supplied to the gas-liquid separator from the methanol stock tank to set a predetermined concentration of 2-5 wt% using water previously supplied to the gas-liquid separator. When the methanol concentration is reached, the fuel is supplied to the fuel cell stack using a fuel supply pump.

Thereafter, after the operation, the unreacted water of the anode and the generated water generated from the cathode are adjusted to a predetermined concentration.

After starting the system for the first time, the fuel solution of the anode continues to circulate, and the water used in the reaction is replenished by using the generated water from the cathode.

If the fuel solution of the anode is continuously circulated by evaporation of the reactants due to the temperature of the stack and crossover (transmission) of methanol and water from the anode to the cathode, ultimately water shortage occurs. In order to supply the water generated in the anode to the anode, it is necessary to additionally install a condenser and a gas-liquid separator on the cathode side.

In the fuel supply system, rational design and operation technology of circulation of generated water, concentration and level control of fuel, and water management control are among the most important technologies for long-term operation and durability of direct methanol fuel cell systems.

The flow rate theoretically calculated when the direct methanol fuel cell system was operated (assuming that all amounts of electricity was completely oxidized in the anode at this time) is:

Using Faraday's law, the required amount of methanol and air, and the amount of carbon dioxide and product water produced can be calculated at normal conditions (at room temperature (298 K), 1 atm) according to the electrochemical reaction equation.

When 1 F of electricity, that is, 96,500 C passes, 1 mol(e-) of electrons, that is, 6 x 10 ²³ electrons move, so the amount of charge that one electron has (e = (96500 C)/(6 x 10 ²³ )= 6 x 10 ^-19 C)) is calculated.

Calculating the amount of electricity (1 C) when a current of 1 A flows for 1 second according to the number of electrons (N _e = 6e-) generated when methanol is oxidized in an electrochemical reaction formula, the amount of methanol required for the anode is N _MeOH = (5.54 x 10 ^-8 )/(0.788) = 7.03 x 10 ^-8 L/sec.

When 1 mol of methanol is consumed at the anode by the whole electrochemical reaction equation, 1.5 mol (48 g) of oxygen is required.

Therefore, the amount of oxygen required at 1A load current is N _O2 = 8.3x10 ^-8 kg/sec = (22.4 L x 8.3 x 10 ^-8 kg/sec)/(32 x 10 ^-3 kg) = 5.81 x 10 ^-5 L/ sec.

Since the proportion of oxygen in the atmosphere is about 21%, the amount of air to be supplied is N _air = (5.81 x 10 ^-5 )/(0.21) = 2.77 x 10 ^-4 L/sec.

When 1 mol (mol) of methanol is consumed, 1 mol (mol) (44 g) of carbon dioxide is produced.

The amount of methanol that is consumed when a load current of ^{1 A 1.73 x 10 -6 (10} 1.73 x -6 mol / sec) The amount of _CO2 N = the carbon dioxide produced, so mol / sec x (22.4 L / mol) = 3.87 x 10 - ⁵ L/sec.

When 1 mol of methanol is consumed, 2 mol (36 g) of water is generated, and the amount of generated water at a load current of 1 A is N _H2O = (1.73 x 10 ^-6 k) x (36 x10 ^-3 ) kg/mol = 6.23 x 10 ^-8 L/sec, and the amount of generated water considering the density of water is N _H2O = (6.23 x 10 ^-8 kg/sec) x (1 L/kg) = 6.23 x 10 ^-8 L/sec.

The utilization rate of methanol is an important factor influencing the performance of a fuel cell.

This is because it determines how much of the fuel and air supplied participate in the electrochemical reaction.

The fuel utilization rate is the ratio of the amount of electricity supplied and the amount of fuel used to generate electricity, and the ratio of the observed amount of electricity to the theoretical output of the fuel cell, that is, methanol utilization ratio = (observed amount of electricity)/(the theoretical output of equivalent methanol).

It is generally reported that the utilization rate of methanol is about 60%, so assuming this, if the product is taken as 1, the reactant should supply 1/0.6 = 1.67.

Therefore, the amount of methanol to be supplied is F _MeOH = 1.67 x 7.03 x 10 ^-8 L/sec = 1.17 x 10 ^-7 L/sec, and the amount of oxygen to be supplied is F _O2 = 5.81 x 10 ^-5 x 1.66 = 9.64 x 10 ^-5 L/sec, and the amount of air to be supplied is F _Air = 1.66 x 2.77 x 10 ^-4 L/sec = 4.02 x 10 ^-4 L/sec.

At this time, the amount of water generated is P _H2O = 6.23 x 10 ^-8 L/sec, and the amount of generated carbon dioxide is P _CO2 = 3.87 x 10 ^-5 L/sec.

The decrease in the utilization rate of methanol in the direct methanol fuel cell system is due to the methanol crossover and the loss of unreacted methanol, and lowering it is very important in determining the performance and efficiency of the direct methanol fuel cell.

That is, it is necessary to reduce the loss by using the supplied methanol as much as possible, and this can be increased by using an electrolyte membrane with less methanol permeation in the stack or by designing and applying a highly efficient gas-liquid separator (fuel mixture tank).

Therefore, these fuel cell systems are widely used in various fields such as automobiles, power plants, and co-generators as well as ships, submarines, and airplanes as clean technologies.

In view of the above, "Liquid moisture control in fuel cell system" of Patent No. 10-0657531 and US Patent Publication US2006/0286415A1, and "fluid separation device of Patent No. 10-0718296 and US Patent Publication US2006/0081130A1 Various fuel cell system related technologies are known, such as "Waiting Patent No. 10-1342536"

However, all of the gas-liquid separators used in the above-described prior art have a problem in that the fuel cell system cannot maintain a constant water level when a slope is formed by inclining in one direction during operation.

In particular, since all of the gas-liquid separators used in the prior art require a water level sensor (level sensor), they faced a fatal problem that the gas-liquid separation function cannot be sustained without using a water level sensor.

Registered Patent No. 10-0657531 US Patent Publication US2006/0286415A1 Registered Patent No. 10-0718296 US Patent Publication US2006/0081130A1 Registered Patent No. 10-1342536

The present invention has been invented to improve the above problems, and it is possible to maintain a constant water level even when the fuel cell system is inclined in one direction during operation, and the gas-liquid separation function can be continued smoothly. The present invention is to provide a gas-liquid separator for a direct methanol fuel cell system equipped with a connection pipe for maintaining a water level and a direct methanol fuel cell system including the same.

In order to achieve the above object, the present invention, in a direct methanol fuel cell system, receiving raw methanol fuel, cathode emissions and anode emissions from the fuel tank, the cathode and the anode, respectively, mixing of fuel and product water, and methanol concentration A gas-liquid separator for diluting, discharging each of the anode and the cathode of the stack into gas and liquid, and supplying the mixed fuel prepared by mixing fuel and product water to the anode; A separator plate built in the gas-liquid separator and partitioning the interior space of the gas-liquid separator into upper and lower chambers; A water supply pipe formed through the separation plate, an upper side disposed in the upper chamber, and a lower side disposed in the basement; And Direct methanol fuel cell system installed with a water level maintenance connector, characterized in that it comprises a water level maintenance connecting tube for maintaining the water level of the methanol diluted fuel to a certain height, so that the gas filled in the basement is delivered to the chamber. It may be possible to provide a solvent separator.

Here, the connection pipe for maintaining the water level is characterized in that the loss and the basement communicate with each other through the outside of the gas-liquid separator.

At this time, the water level maintenance connecting pipe, one end portion installed inside the basement, the other end portion installed inside the chamber, the one end portion and the other end portion is connected through the outside of the gas-liquid separator It is characterized by.

And, the cathode discharge inlet is formed in the upper chamber is supplied with the cathode discharge, the gas outlet is formed in the chamber to discharge the gas to the outside, and the anode discharge inlet is formed in the base to supply the anode discharge, the It is formed in a basement further comprises a stock solution methanol inlet through which the stock solution methanol fuel is supplied from the fuel tank, and a fuel supply port formed in the basement to supply the mixed fuel from the anode, wherein the water level in the basement is the anode discharge. A water level sensor for measuring the water level in the basement is located by placing the distal end of the connecting pipe for maintaining the water level perpendicular to the center of the separating plate orthogonally in the vertical direction so as to be kept lower than the inlet port and higher than the fuel supply port. It is characterized by being omitted.

In addition, the connection pipe for maintaining the water level maintains a constant water level even when the direct methanol fuel cell system is inclined in any direction during operation to form an inclination, and the gas-liquid separator continues the gas-liquid separation function. It characterized in that the distal end of the connection pipe for maintaining the water level is located on a virtual line that orthogonally penetrates the center of the separator in the vertical direction.

In addition, the distal end of the connection pipe for maintaining the water level is formed to be higher than the flat water level of the mixed fuel in the basement, and the flat water level is an average level of the mixed fuel in the basement during operation of the stack. .

In addition, the distal end of the connection pipe for maintaining the water level is characterized in that the liquid fuel is installed at a position that is 5 to 80% of the total volume of the base.

In addition, the ratio of the liquid level of the loss to the liquid level of the basement is 1/10 to 1/3.

And, the center of the upper end and the lower end of the water supply pipe is disposed on a virtual line orthogonally penetrating the center of the separation plate in the vertical direction, the distal end of the water level maintenance connecting pipe is located on the virtual line and for maintaining the water level In order to avoid interference with the distal end of the connecting pipe, it is characterized in that it further comprises a bent pipe portion formed in the middle of the water supply pipe.

In addition, the inner diameter of the water supply pipe and the connection pipe for maintaining the water level is characterized in that 3 to 10 mm.

In addition, the connection pipe for maintaining the water level and the gas-liquid separator is characterized in that formed of one of corrosion-resistant stainless steel (STS), polypropylene (PP), polyethylene (PE), ABS or polycarbonate (PC).

On the other hand, the present invention is the gas-liquid separator described above; And at least one stacked membrane-electrode assembly (MEA), an anode for discharging unreacted emissions including unreacted methanol, water and carbon dioxide, and an anode for discharging discharges including unreacted air and product water, , A stack for producing electricity by receiving fuel through a fuel pump from the gas-liquid separator and receiving air or oxygen from an air pump; An anode heat exchanger for liquefying the generated water contained in the discharge discharged from the cathode to be supplied to the gas-liquid separator; An anode heat exchanger that cools the unreacted effluent heated to the reaction heat by the electrochemical reaction occurring in the anode to a certain level; And an air supply unit supplying the air or the oxygen to the cathode for supply of the oxygen used as an oxidant in the reaction of the cathode, wherein the gas-liquid separator receives methanol fuel through a methanol pump from a fuel tank, Characterized in that the gas and liquid contained in the unreacted emissions discharged from the anode and the exhaust discharged from the cathode are separated, and water and methanol are mixed to supply a methanol mixed fuel diluted to an appropriate concentration to the anode. Of course, it is also possible to provide a direct methanol fuel cell system.

According to the present invention having the above configuration, the following effects can be achieved.

First, the present invention makes it possible to control the level of fuel without the need for a sensor.

And, the present invention has no fuel leakage even if the inclination is inclined in either direction during operation and maintains a constant water level and the gas-liquid separation function can also be continued without being interrupted.

In addition, the present invention is to maintain the level of the mixed fuel even if the flow rate of the fluid flowing into the base of the gas-liquid separator increases.

In particular, the present invention can simplify the configuration of the system because it can simultaneously function for mixing fuel and product water, diluting methanol concentration, and separating gas and liquid from the anode and cathode emissions.

In addition, the present invention can minimize the loss of methanol discharged together with carbon dioxide vaporized in the gas-liquid separation process for reuse of the used fuel.

1 is a schematic diagram showing the configuration of a direct methanol fuel cell system according to an embodiment of the present invention
2 is a view schematically showing the configuration of a gas-liquid separator having a water level maintenance connecting pipe installed in a direct methanol fuel cell system according to an embodiment of the present invention.
3 is a view schematically showing a structure in which a gas-liquid separator in which a water level maintaining connector of a direct methanol fuel cell system according to an embodiment of the present invention is installed is inclined at an inclined angle.
4 is to mount the gas-liquid separator installed in the fuel cell stack system is installed in the water level maintenance connecting pipe of the direct methanol fuel cell system according to an embodiment of the present invention, before, after, left and right to be inclined to 30 ° each Curve showing the output characteristics over time of the fuel cell stack measured at the time
5 is mounted on the fuel cell stack system equipped with a gas-liquid separator installed in the water level maintenance connecting pipe of the direct methanol fuel cell system according to an embodiment of the present invention, before, after, inclined to 30 °, respectively in the left and right direction Photo showing gas-liquid separator when measuring output characteristics over time of fuel cell stack

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings.

However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms.

In the present specification, this embodiment is provided to make the disclosure of the present invention complete, and to fully inform the scope of the invention to those skilled in the art to which the present invention pertains.

And the present invention is only defined by the scope of the claims.

Thus, in some embodiments, well-known components, well-known operations, and well-known techniques are not specifically described in order to avoid obscuring the present invention.

In addition, the same reference numerals throughout the specification refer to the same components, and the terms used (referred to) in this specification are for describing the embodiments and are not intended to limit the present invention.

In the present specification, the singular form also includes the plural form unless specifically stated in the phrase, and the components and operations referred to as'comprising (or, provided)' do not exclude the presence or addition of one or more other components and operations. .

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used as meanings commonly understood by those skilled in the art to which the present invention pertains.

Also, terms that are defined in a commonly used dictionary are not ideally or excessively interpreted unless they are defined.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

For reference, Figure 1 is a schematic diagram showing the configuration of a direct methanol fuel cell system according to an embodiment of the present invention.

And, Figure 2 is a view schematically showing the configuration of the gas-liquid separator 20 is installed in the water level maintenance connecting pipe 250 of the direct methanol fuel cell system according to an embodiment of the present invention.

And, FIG. 3 is a view schematically showing a structure in which the gas-liquid separator 20 in which the water level maintenance connecting pipe 250 of the direct methanol fuel cell system according to an embodiment of the present invention is formed at an inclination angle α is inclined. .

In addition, FIG. 4 is equipped with a gas-liquid separator 20 having a water level maintenance connector 250 installed in a direct methanol fuel cell system according to an embodiment of the present invention in a fuel cell stack system, before and after the gas-liquid separator 20. , It is a curve showing the output characteristics over time of the fuel cell stack 10 measured when it is inclined at 30° in the left and right directions, respectively.

In addition, FIG. 5 is equipped with a gas-liquid separator 20 in which the water level maintenance connecting pipe 250 of the direct methanol fuel cell system according to an embodiment of the present invention is installed in a fuel cell system, before and after the gas-liquid separator 20, It is a photograph showing the gas-liquid separator 20 when measuring the output characteristics over time of the fuel cell stack 10 by inclining 30° in the left and right directions, respectively.

For reference, the dotted arrows in FIGS. 2 and 3 indicate the flow direction of the fluid flowing in the corresponding direction.

The direct methanol fuel cell system according to an embodiment of the present invention is a stack 10, a gas-liquid separator 20, a fuel tank 30, a heat exchanger 40, 50, an air supply unit 70, 61 as shown in FIG. It includes.

The stack 10 is a part for producing electricity by receiving fuel from the gas-liquid separator 20 through the fuel pump 62 and receiving air (oxygen) from the air pump 61, one or more stacked membranes /Includes electrode assembly (MEA).

The gas-liquid separator 20 is supplied with methanol fuel from the fuel tank 30 through the methanol pump 63, and unreacted emissions (unreacted methanol, water, and carbon dioxide) discharged from the anode of the stack 10 and from the cathode Gas (unreacted air, carbon dioxide) and liquid (unreacted methanol, water, and generated water) contained in the discharged product (unreacted air, product water) are separated, and methanol diluted with an appropriate concentration by mixing water and methanol It serves to supply the mixed fuel to the anode.

The cathode discharged from the cathode has a lot of generated water discharged in a gaseous state, so the generated water is liquefied using the cathode heat exchanger 50 to be supplied to the gas-liquid separator 20.

The fuel tank 30 stores the methanol fuel stock solution. As described above, the reaction at the anode can be used as fuel only after mixing with water in the gas-liquid separator 20 since water as well as methanol is used as a reactant. . The fuel of the fuel tank 30 is supplied to the gas-liquid separator 20 through a methanol pump 63.

The air supply units 70 and 61 are parts for supplying air to the air electrode to supply oxygen used as an oxidizing agent in the reaction of the air electrode, and may include an air filter 70 and an air pump 61.

Although a structure using air is illustrated in this embodiment, oxygen may be supplied and used, and in this case, the air filter 70 is not used.

On the other hand, the anode discharged from the anode is heated to a high temperature (60 to 80°C) due to the reaction heat from the electrochemical reaction at the anode, so the temperature of the anode discharge is set to an appropriate level by using the anode heat exchanger 40. It can be cooled.

A part of interest in the present invention is the gas-liquid separator 20 used for the reuse of fuel and water.

In the stack 10, methanol, which is fuel, is evaporated or discharged as exhaust gas through a gas-liquid separator 20 for discharging gaseous carbon dioxide generated by a methanol oxidation reaction and recovering methanol and water, and thus methanol is unnecessary. Is consumed.

Unnecessary consumption of methanol leads to a decrease in the efficiency of use of methanol, i.e. a decrease in system efficiency.

According to the direct methanol fuel cell system of the present invention, by designing a gas-liquid separator 20 that functions as a mixture of fuel and product water, dilution of methanol concentration, and gas-liquid separation of the anode and cathode emissions, the complex structure of the system is simplified and gas-liquid It is possible to minimize the loss of methanol during the separation process.

In addition, the system maintains a constant level of water even during operation and ensures that the gas-liquid separation function works well even when the system is inclined.

Hereinafter, the gas-liquid separator 20 in which the water level maintenance connecting pipe 250 of the direct methanol fuel cell of the present invention is installed will be described in more detail with reference to FIGS. 2 and 3.

The gas-liquid separator 20 according to an embodiment of the present invention includes a loss 230 and a basement 210 separated by a separation plate 220 as shown in FIG. 2.

An air cathode discharge inlet 231 through which the cathode discharge discharged from the cathode is supplied and a gas discharge hole 232 through which gas is discharged are formed in the upper chamber 230.

In the basement 210, the anode discharge inlet 213 through which the anode discharge discharged from the anode is supplied, and the stock methanol inlet 211 through which methanol fuel is supplied from the fuel tank 30, and fuel supply for supplying mixed fuel to the anode The sphere 212 is formed.

In addition, inside the basement 210, the level control of the mixed fuel is possible without a sensor, and a connection pipe 250 for maintaining the water level is formed so that there is no fuel leakage even if an inclination is formed by inclining in either direction.

A water supply pipe 240 is formed in the separation plate 220, and the water supply pipe 240 penetrates through the separation plate 220, the upper portion of which is disposed in the upper portion 230 of the gas-liquid separator 20, and the lower portion of the water-liquid separator. It is placed in the basement 210 of 20.

On the other hand, the gas-liquid separator 20 is formed with a connection pipe 250 for maintaining the water level so that gas such as carbon dioxide filled in the basement 210 is transferred to the chamber 230.

In addition, the gas-liquid separator 20 does not need to separately install a level sensor for measuring the water level in the basement 210 because the water level in the basement 210 is maintained at the position of the connector 250 for maintaining the anode level.

In addition, the basement 210 may be further provided with a concentration measurement sensor 270 for measuring the methanol concentration, and if the concentration of the methanol in the concentration measurement sensor 270 is less than the proper range, the crude methanol is supplied from the fuel tank 30. do.

The water level maintenance connecting pipe 250 is formed to connect the chamber 210 and the chamber 230 to allow the mixed fuel higher than a certain level to move to the chamber 230 from the inside of the chamber 210.

The connection pipe 250 and the gas-liquid separator 20 for maintaining the water level are preferably made of a metal or plastic material resistant to methanol, and representative examples thereof are corrosion-resistant stainless steel (STS), polypropylene (PP), and polyethylene (PE). ) Or polycarbonate (PC).

One of the connecting pipes 250 for maintaining the water level may be installed, and is preferably formed higher than the level of the normal level of the mixed fuel of the basement 210.

Here, the "peace level" refers to the average level of the mixed fuel in the basement 210 of the gas-liquid separator 20 during the operation of the fuel cell.

Looking at the detailed structure of the gas-liquid separator 20, considering the volume of the basement 210 and the loss 230, the volume ratio corresponding to the water level of the loss 230 to the water level of the basement 210 is 1/10 to 1 It is desirable to keep it at /3.

If the volume ratio is less than 1/10, the volume of the loss 230 is too small, and a large amount of the generated water supplied to the loss 230 is discharged together with air through the gas outlet 232, and the water to be supplied to the basement 210 is insufficient. The problem arises.

If the volume ratio is more than 1/3, the volume of the loss 230 is too large, and a large excess of the generated water supplied to the loss 230 is not discharged to the gas outlet 232, but is supplied to the basement 210 and water remains excessive. A problem arises.

In addition, the inner diameter of the water supply pipe 240 is preferably 3 to 10 mm and the inner diameter of the connection pipe 250 for maintaining the water level is 3 to 10 mm.

When the inner diameter of the water supply pipe 240 is less than 3 mm, the surface tension of the water supply pipe 240 increases, and it is difficult for the water generated in the loss 230 to move to the basement 210 through the water supply pipe 240.

If the inner diameter of the water supply pipe 240 is more than 10 mm, some of the unreacted air and carbon dioxide supplied to the chamber 230 cannot be discharged to the gas outlet 232 and move to the basement 210 through the water supply pipe 240 There is a problem that can cause symptoms.

When the inner diameter of the connection pipe 250 for maintaining the water level is less than 3 mm, the surface tension of the connection pipe 250 for maintaining the water level increases, so that the pressure in the basement 210 increases and the carbon dioxide and excess fuel in the basement 210 for maintaining the water level It is difficult to move to the loss 230 through the connector 250.

If the inner diameter of the connector 250 for maintaining the water level is greater than 10 mm, carbon dioxide and excess fuel supplied to the basement 210 are faced with the problem of moving to the loss 230 through the connector 250 for maintaining the water level. Is done.

The gas outlet 232 is an outlet through which unreacted air, which is an anode emission, and produced carbon dioxide, which is an anode emission, are discharged outside the fuel cell system.

Therefore, the gas outlet 232 should be designed so that only unreacted air and product carbon dioxide are discharged, and product water, unreacted methanol and water are not discharged.

To achieve this purpose, if the gas outlet 232 is designed to pass only unreacted air and product carbon dioxide and not methanol or water, water shortage or loss of methanol can be prevented.

To achieve this purpose, when a porous hydrophobic separator (not shown) is installed in the gas outlet 232, it is possible to pass liquids such as methanol or water, but only unreacted air or gas such as carbon dioxide.

To this end, a hydrophobic membrane such as polytetrafluoroethylene (PTFE), ethylenetetrafluoroethylene (ETFE) or polyvinylidene fluoride (PVDF) may be used as the porous hydrophobic separator.

The porous hydrophobic separator is made of porosity, and the pore size is 0.001 to 0.05 mm, and the thickness is 0.01 to 0.1 mm.

In addition, to impart mechanical strength of the porous hydrophobic separator, a support membrane having pores larger than the pores of the porous hydrophobic separator may be installed on the upper and lower surfaces of the porous hydrophobic separator.

If the pore size of the porous hydrophobic separator is too large, liquid such as methanol or water may pass through and be discharged to the outside, and if the pore size is too small, the passage of methanol or water is difficult and the pressure of gas or liquid may rise inside the chamber. There is this.

Therefore, the pore size of the porous hydrophobic separator is preferably 0.001 to 0.05 mm, and more preferably to be formed in the range of 0.01 to 0.03 mm.

The porous hydrophobic separator preferably has hydrophobicity rather than hydrophilicity in order to prevent pores from being blocked by water or methanol.

Hereinafter, a process in which methanol fuel, anode discharge and cathode discharge are mixed and supplied to the anode through the gas-liquid separator 20 of the direct methanol fuel cell system according to an embodiment of the present invention will be described in detail.

First, the cathode discharge discharged from the cathode through the cathode discharge inlet 231 of the chamber 230 is supplied.

The cathode discharge includes water (water) produced at the cathode, water and methanol crossover to the cathode through the electrolyte membrane, and air supplied for an oxygen reduction reaction.

In addition, the anode discharge discharged from the anode through the anode discharge inlet 213 of the basement 210 is supplied.

The anode emissions include methanol and water supplied to the anode, and carbon dioxide produced by the methanol oxidation reaction.

Along with this, the methanol fuel stock solution supplied from the fuel tank 30 is supplied to the stock solution methanol inlet 211 of the basement 210.

When the anode discharge and methanol fuel are supplied to the basement 210 through the anode discharge inlet 213 and the stock solution methanol inlet 211, the bottom of the base 210 is filled with methanol and water, and the top is filled with air including carbon dioxide.

When the anode emission and methanol fuel are continuously supplied to the chamber 210, the carbon dioxide moves through the connecting pipe 250 for maintaining the water level and moves to the chamber 230 due to the increase in the pressure inside the chamber 210.

At this time, the exhaust gas contains not only carbon dioxide, but also vaporized methanol, and is collected by the water filled in the chamber 230 while moving to the chamber 230 through the connection pipe 250 for maintaining the water level.

When the cathode 230 is continuously supplied with the cathode emission, the generated water (water) is filled, and when the water level rises and becomes higher than the upper level of the water supply pipe 240, water overflows into the water supply pipe 240. Water of the loss 230 is supplied to the basement 210.

The upper portion of the upper room 230 is filled with carbon dioxide discharged through the connection pipe 250 for maintaining the water level in the basement 210 and air supplied through the cathode discharge inlet 231 and finally external through the gas outlet 232 Is discharged.

The diluted methanol filled in the basement 210, that is, the mixed fuel is supplied to the anode through the fuel supply port 212 by the fuel pump 62.

FIG. 3 shows a structure in which the gas-liquid separator 20 in which the water level maintenance connecting pipe 250 shown in FIG. 2 is installed forms an inclination angle α .

In the gas-liquid separator 20 in which the water level maintenance connecting tube 250 is installed, the distal end of the water level maintaining connecting tube 250 is positioned on the virtual line L penetrating orthogonally to the center of the separation plate 220 in the vertical direction. Even if the gas-liquid separator 20 is inclined in any direction in all directions to form an inclined angle α , it is possible to continuously maintain a constant water level.

If the distal end of the water level maintenance connecting pipe 250 is not located on the above-mentioned virtual line L, the distal end of the water level maintaining connecting pipe 250 is biased in one direction of up, down, left, and right, and thus is lost in the corresponding biased direction ( 230) and a lot of fuel and generated water in the basement 230 may be leaked to the outside.

In addition, as shown in FIGS. 2 and 3, the water supply pipe 240 may further include a bent pipe portion 241.

That is, the center of each of the upper end and the lower end of the water supply pipe 240 is disposed on the above-described virtual line (L) that orthogonally crosses the center of the separation plate 220 in the vertical direction, the connection pipe 250 for maintaining the water level When the distal end of the is disposed on the virtual line (L) as described above, interference between the distal end of the water level maintenance connecting pipe 250 and the middle portion of the water supply pipe 240 occurs.

The bent pipe portion 241 avoids interference between the distal end of the connection pipe 250 for maintaining the water level and the middle portion of the water supply pipe 240, and allows a smooth flow of water through the water supply pipe 240 to allow the water supply pipe It will be able to be formed to bend at a constant curvature in the middle of (240).

Meanwhile, it is preferable that the level of the mixed fuel filled in the basement 210 occupies 50 to 80 vol% of the total volume of the basement 210.

If the level of the mixed fuel filled in the basement 210 is less than 50 vol% of the total volume of the basement 210, when the gas-liquid separator 20 is inclined, the water produced in the loss 230 flows through the water supply pipe 240. ).

When the volume of the basement 210 exceeds 80 vol%, when the gas-liquid separator 20 is inclined, the pressure of the basement 210 increases by the carbon dioxide and fuel supplied to the basement 210 and 50 of the total volume of the basement 210 There is a disadvantage in that only about vol% of fuel remains in the basement 210 and the remaining fuel is discharged to the outside.

The above-described inclination angle ( α ) may range from 0° to 90°, and the gas-liquid separator 20 maintains a constant water level even when it is inclined to 90° for a temporary time within 1 to 10 minutes. The gas-liquid separation function can be performed.

Through this circulation process, water can be continuously reused, carbon dioxide can be prevented from entering the fuel supplied to the anode, and the loss of methanol discharged to the outside in a vaporized state can be minimized.

Meanwhile, FIG. 4 manufactures a gas-liquid separator 20 in which the water level maintenance connecting pipe 250 of the direct methanol fuel cell system according to an embodiment of the present invention shown in FIG. 2 is installed, and mounts it in a fuel cell stack system. It shows the output characteristics over time of the fuel cell stack according to the inclination angle of the gas-liquid separator 20.

In FIG. 4, the area A of the fuel cell stack is measured by tilting the gas-liquid separator 20 forward 30°, the area B 30° rearward, the area C 30° left, and the area D 30° rightward. It shows.

In FIG. 4, the stack is 310~325W (6.23 hours) (11.15~11.16A, 27.96~) even if the machined gas-liquid separator mounted on the fuel cell system is maintained for 1.5 hours at a front/back/left/right 30° slope, respectively. 29.21V).

Also, the water level was kept constant at the position of the connector for maintaining the water level (water level: 95 mm, fuel amount: 0.95 L) without the aid of a water level sensor.

FIG. 5 is equipped with a gas-liquid separator 20 having a water level maintenance connector 250 installed in a direct methanol fuel cell system according to an embodiment of FIG. 2 installed in a fuel cell stack system, and transferring the gas-liquid separator 20 It shows the gas-liquid separator 20 when measuring the output characteristics over time of the fuel cell stack when it is inclined at 30 degrees in each of the rear/left/right directions.

In FIG. 5, (a) is 30° forward of the gas-liquid separator 20, (b) 30° of the rear, (c) 30° of the left, and (d) 30° to the right of the fuel cell stack. It shows the gas-liquid separator 20 when measuring the output change over time (see Fig. 4) of (10).

As shown in Figure 5, even if the gas-liquid separator 20 is inclined to 30 degrees in either direction of the front / rear / left / right, the water level of the gas-liquid separator 20 is kept constant at the end position of the water level maintenance connector 250 Became.

As described above, the present invention enables direct maintenance of a water level maintenance connecting tube to maintain a constant level of water even when the fuel cell system is inclined in any direction during operation, and maintains a smooth liquid separation function. It can be seen that the basic technical idea is to provide a gas-liquid separator for a methanol fuel cell system and a direct methanol fuel cell system including the same.

And, within the scope of the basic technical idea of the present invention, for those of ordinary skill in the art, the above-described shape of the bent pipe portion 241 may be formed into a semi-circular shape or a semi-elliptical shape so that an arc-shaped flow path is formed. Of course, if the structure capable of avoiding the interference with the distal end of the water level maintenance connecting pipe 250, many other modifications and applications are also possible, such as, for example, forming a "c" shape or a "V" shape. to be.

10...stack
20... gas-liquid separator
30...fuel tank
40... anode heat exchanger
50...air pole heat exchanger
61...air pump (blower)
62...Fuel pump
63... methanol pump
70...air filter
210... you
211... stock methanol inlet
212...Fuel supply port
213...Anode discharge inlet
220...
230... Lost
231...air electrode discharge inlet
232...gas outlet
240...water supply pipe
241...
250... water level maintenance connector
270...Fuel concentration sensor
L... virtual ship

Claims (12)

In a direct methanol fuel cell system, raw methanol fuel, cathode emissions and anode emissions are received from the fuel tank, the cathode and the anode, respectively, mixing the fuel and product water, diluting the methanol concentration, and discharging the anode and cathode electrodes of the stack. A gas-liquid separator for separating gas and liquid and supplying a mixed fuel prepared by mixing fuel and product water to an anode;
A separator plate built in the gas-liquid separator and partitioning the interior space of the gas-liquid separator into upper and lower chambers;
A water supply pipe formed through the separation plate, an upper side disposed in the upper chamber, and a lower side disposed in the basement; And
It is for direct methanol fuel cell system installed with a water level maintenance connector, characterized in that it comprises a water level maintenance connector that allows the gas filled in the basement to be delivered to the chamber and maintains the level of the methanol diluted fuel at a constant height. Gas-liquid separator.
The method according to claim 1,
The water level maintenance connector,
A gas-liquid separator for a direct methanol fuel cell system equipped with a connection pipe for maintaining a water level, characterized in that the chamber communicates with the chamber through the outside of the gas-liquid separator.
The method according to claim 1,
The water level maintenance connector,
One end portion installed inside the basement,
And the other end portion installed inside the loss,
The one end portion and the other end portion is a gas-liquid separator for a direct methanol fuel cell system equipped with a connection pipe for maintaining the water level, characterized in that connected through the outside of the gas-liquid separator.
The method according to claim 1,
An anode discharge inlet formed in the chamber to which the cathode discharge is supplied,
A gas outlet formed in the chamber to discharge gas to the outside;
An anode discharge inlet formed in the basement and supplied with the anode discharge,
A stock solution methanol inlet formed in the basement and supplied with the stock solution methanol fuel from the fuel tank;
It is formed on the base and further includes a fuel supply port for supplying the mixed fuel from the anode,
The lower end of the connecting pipe for maintaining the water level is positioned on a virtual line orthogonally orthogonally penetrating the center of the separating plate so that the water level of the basement is maintained lower than the anode discharge inlet and higher than the fuel supply port. A liquid-liquid separator for a direct methanol fuel cell system equipped with a water level maintaining connector, characterized in that a water level sensor for measuring the water level is omitted.
The method according to claim 1,
The water level maintenance connector,
The direct methanol fuel cell system maintains a constant water level even when inclined in any direction during operation to form a slope, so that the gas-liquid separator can continue the gas-liquid separation function,
A gas-liquid separator for a direct methanol fuel cell system equipped with a water level-maintaining connector, characterized in that the distal end of the water level-maintaining connector is located on an imaginary line perpendicularly penetrating the center of the separator in the vertical direction.
The method according to claim 1,
The distal end portion of the connecting pipe for maintaining the water level is formed higher than the normal water level of the mixed fuel in the basement,
The normal water level is a gas-liquid separator for a direct methanol fuel cell system equipped with a connection pipe for maintaining a water level, characterized in that the average level of the mixed fuel in the basement during operation of the stack.
The method according to claim 1,
The distal end of the water level connection connector,
A gas-liquid separator for a direct methanol fuel cell system equipped with a connection pipe for maintaining a water level, characterized in that the liquid fuel is installed at a position of 5 to 80% of the total volume of the basement.
The method according to claim 1,
A gas-liquid separator for a direct methanol fuel cell system equipped with a water level maintenance connector, characterized in that a volume ratio corresponding to the liquid level of the basement to the liquid level of the basement is 1/10 to 1/3.
The method according to claim 1,
The center of the upper end and the lower end of the water supply pipe is disposed on a virtual line orthogonally penetrating the center of the separation plate in the vertical direction, and the distal end of the water level maintaining connector is located on the virtual line and the water level maintaining connector A gas-liquid separator for a direct methanol fuel cell system equipped with a connection pipe for maintaining a water level, further comprising a bent pipe portion formed in an intermediate portion of the water supply pipe to avoid interference with an end portion of the water.
The method according to claim 1,
A gas-liquid separator for a direct methanol fuel cell system equipped with a water level maintenance connection tube, characterized in that the water supply pipe and the water level maintenance connection tube have an inner diameter of 3 to 10 mm.
The method according to claim 1,
The water level maintaining connector and the gas-liquid separator are formed of one of corrosion-resistant stainless steel (STS), polypropylene (PP), polyethylene (PE), ABS or polycarbonate (PC). Installed gas-liquid separator for direct methanol fuel cell systems.
The gas-liquid separator according to any one of claims 1 to 11;
And at least one stacked membrane-electrode assembly (MEA), an anode for discharging unreacted emissions including unreacted methanol, water and carbon dioxide, and an anode for discharging discharges including unreacted air and product water, , A stack for producing electricity by receiving fuel through a fuel pump from the gas-liquid separator and receiving air or oxygen from an air pump;
An anode heat exchanger for liquefying the generated water contained in the discharge discharged from the cathode to be supplied to the gas-liquid separator;
An anode heat exchanger that cools the unreacted effluent heated to the reaction heat by the electrochemical reaction occurring in the anode to a certain level; And
It includes an air supply for supplying the air or the oxygen to the cathode for the supply of the oxygen used as an oxidizing agent in the reaction of the cathode,
The gas-liquid separator receives methanol fuel from a fuel tank through a methanol pump, separates gas and liquid contained in the unreacted emissions discharged from the anode and the exhaust discharged from the cathode, and mixes water and methanol. A direct methanol fuel cell system, characterized in that a methanol mixed fuel diluted to an appropriate concentration is supplied to the anode.

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