KR20090111241A - Fuel cell system provided with air inlet valve for preventing deterioration of fuel cell and method for preventing deterioration of fuel cell using air inlet valve - Google Patents

Abstract

PURPOSE: A fuel battery system having gas inhalation valve for preventing deterioration of fuel battery is provided to prevent deterioration generated by exchanging oxide of cathode through electrolytic membrane. CONSTITUTION: A fuel battery system comprises a hydrogen recirculation blower (117), recirculation line blocking valve (116) and hydrogen purge valve (118). The front end of the hydrogen recirculation blower comprises gas inhalation line (115a) and gas inhalation valve (119). A controller (131,132) regulates each valve and hydrogen recirculation blower to remove residual hydrogen.

Description

Fuel cell system provided with air inlet valve for preventing deterioration of fuel cell and method for preventing deterioration of fuel cell using air inlet valve}

The present invention relates to a fuel cell system having an air intake valve for preventing deterioration of a fuel cell, and a method for preventing deterioration of a fuel cell using an air intake valve, wherein a hydrogen recirculation blower and an air intake valve are used during shutdown of the fuel cell system. The present invention relates to a fuel cell system and a method for preventing deterioration of a fuel cell, so that residual hydrogen on the anode side can be quickly removed, thereby preventing deterioration of the fuel cell.

A fuel cell is a kind of power generation device that converts chemical energy of fuel into electric energy by electrochemical reaction in the fuel cell stack without converting it into heat by combustion. It can also be applied to the power supply of electrical / electronic products, especially portable devices.

Examples of such fuel cells include a polymer electrolyte membrane fuel cell (PEMFC), which is most frequently researched as a power supply for driving a vehicle, and a membrane electrolyte based on an electrolyte membrane in which hydrogen ions move. Membrane Electrode Assembly (MEA) with a catalytic electrode layer on both sides, a gas diffusion layer (GDL) that distributes the reactants evenly and delivers the generated electrical energy. And a gasket and fastening mechanism for maintaining the airtightness and proper fastening pressure of the reactor bodies and cooling water, and a bipolar plate for moving the reactor bodies and cooling water.

In the fuel cell, hydrogen as the fuel and oxygen (air) as the oxidant are respectively supplied to the anode and the cathode of the membrane electrode assembly through the flow path of the separator, and the hydrogen is the anode ('fuel electrode' or 'oxidation'). Oxygen (air) is supplied to the cathode ('air electrode' or 'oxygen electrode', also known as 'reduction electrode').

Supplied to the anode hydrogen is a hydrogen ion (proton, H ⁺⁾ and electrons by the electrode catalyst constructed on both sides of the electrolyte membrane (electron, e ^-) are decomposed into, passed through only the hydrogen ion in the optional electrolyte membrane cation exchange membrane The electrons are transferred to the cathode through the gas diffusion layer and the separation plate which is a conductor.

In the cathode, the hydrogen ions supplied through the electrolyte membrane and the electrons transferred through the separator meet with oxygen in the air supplied to the cathode by the air supply device to generate a reaction.

At this time, due to the movement of hydrogen ions that occur, the flow of electrons through the external conductor occurs, the current is generated by the flow of these electrons.

The electrode reaction of the fuel cell is represented by the following equation.

[Reaction at the ^{_{anode] 2H 2 → 4H + + 4e}} -

[Reaction at ^{_{cathode] O 2 + 4H + + 4e}} - → 2H 2 O

[Overall reaction] 2H ₂ + O ₂ → 2H ₂ O + electrical energy + thermal energy

As shown in the above scheme, the hydrogen molecules are decomposed at the anode to generate four hydrogen ions and four electrons. The generated electrons move through an external circuit to generate a current, and the generated hydrogen ions move to the cathode through the electrolyte membrane to perform a cathode reaction.

And, as is well known, the fuel cell system includes a fuel cell stack that largely generates electric energy, a hydrogen supply device for supplying hydrogen as fuel to the fuel cell stack, and air (oxygen) as an oxidant required for an electrochemical reaction to the fuel cell stack. Air (oxygen) supply device to supply fuel, thermal management system (TMS) that removes reaction heat from fuel cell stack to outside of system, controls operating temperature of fuel cell stack, and performs water management function, and fuel And a fuel cell system controller that controls the overall operation of the cell system.

Here, the hydrogen supply device includes a hydrogen tank, a high pressure / low pressure regulator, a hydrogen recirculation device, and the like, the air supply device includes an air blower, a humidifier, and the like, and the heat and water management system includes a coolant pump, a radiator, and the like.

The high pressure hydrogen supplied from the hydrogen tank of the hydrogen supply device passes through a high pressure / low pressure regulator in turn and is supplied to the fuel cell stack at low pressure. In the hydrogen recycle device, a blower is installed on a recycle line to install a hydrogen electrode (anode) of the stack. By recycling the remaining unreacted hydrogen in the hydrogen back to the hydrogen electrode to promote the reuse of hydrogen.

In addition, with the operation of the stack in the fuel cell vehicle, nitrogen in the air used as the oxidant for the fuel cell reaction and generated water generated at the cathode (air electrode) cross over the electrolyte membrane and move to the anode side (hydrogen electrode). At this time, since nitrogen deteriorates the performance of the stack by lowering the partial pressure of hydrogen, and generated water inhibits the movement of hydrogen by blocking the flow path, it is necessary to secure stable performance of the stack through periodic purge of the hydrogen electrode. To this end, a fuel cell system is usually equipped with a device for purging hydrogen.

Unreacted hydrogen from the stack is fed back to the stack via a hydrogen recycle line, but part of the hydrogen is discharged through a hydrogen purge valve to purge the droplets of the separator and increase hydrogen utilization.

On the other hand, when the system is shut down after driving the fuel cell vehicle, if the fuel cell voltage is above a certain voltage, and hydrogen remains on the anode side and oxygen remains on the cathode side, hydrogen and oxygen are exchanged through the electrolyte membrane to form a catalyst layer. It is known to accelerate the deterioration of.

To prevent this, various techniques have been proposed to remove oxygen and hydrogen on the cathode side and anode side, respectively, while reducing the fuel cell voltage during system shutdown (ie, system shutdown).

As a representative example, Korean Patent Laid-Open Publication No. 2006-66124 has a method of removing oxygen from a cathode while lowering a fuel cell voltage by having an auxiliary load connected in parallel with a stack to connect an auxiliary load when a system is stopped. In this case, complex circuit configurations, such as switches for the auxiliary loads and the opening and closing of the auxiliary load side circuits, must be added.

In addition, Korean Patent Laid-Open Publication No. 2005-86532 includes a separate pipe connecting the cathode pipe and the anode pipe, and a valve installed therein, and supplies air to the anode pipe by driving an air blower when the system is shut down, thereby remaining hydrogen in the stack. Was removed. However, in this case, since the piping connecting the cathode-side piping and the anode-side piping must be configured, there is a design difficulty and the piping structure may be complicated.

Accordingly, the present invention has been invented in view of the above, and the conventional fuel cell system simply includes an air intake line and an air intake valve, so that the hydrogen recirculation blower and the air intake valve are shut down when the fuel cell system is shut down. It is an object of the present invention to provide a fuel cell system and a method for preventing deterioration of a fuel cell, by which residual hydrogen on the anode side is quickly removed to prevent deterioration of the fuel cell.

In order to achieve the above object, the present invention is a fuel cell system comprising a hydrogen recycle blower, a recycle line shut-off valve and a hydrogen purge valve,

An air suction line branched from the hydrogen recycle line at the front of the hydrogen recycle blower and an air suction valve installed therein,

The controller controls each of the valves and the hydrogen recirculation blower so that external air sucked into the air intake line by the hydrogen recirculation blower purges the fuel cell anode side to remove residual hydrogen during shutdown of the fuel cell system. do.

In addition, the present invention is to close the recirculation line shutoff valve on the hydrogen recirculation line inlet side in the state of shutting off the hydrogen supply of the fuel cell stack during shutdown of the fuel cell system,

Open the air purge valve in front of the hydrogen purge valve and the hydrogen recirculation blower, and then drive the hydrogen recirculation blower for a certain time.

Provided is a method for preventing deterioration of a fuel cell using an air intake valve, wherein external air sucked from the air intake valve by the hydrogen recirculation blower purges the fuel cell anode side to remove residual hydrogen.

In addition, the air and impurities supplied when the residual hydrogen is removed from the fuel cell anode close the air intake valve and open the hydrogen purge valve and the recirculation line shutoff valve while hydrogen is supplied to the fuel cell stack at the start of the fuel cell system. The hydrogen recycle blower can be driven and then removed by a hydrogen purge operation.

Accordingly, in the present invention, when the fuel cell system is shut down, the air is sucked out and at the same time, the hydrogen remaining on the anode side is quickly discharged to the outside by the sucked air so that the air is distributed without hydrogen on the anode side. Likewise, the deterioration generated when the residual hydrogen is exchanged with the cathode side oxygen through the electrolyte membrane is prevented.

In addition, impurities of the air and fuel cell anode supplied for removing residual hydrogen are quickly removed through hydrogen purge at the start of the fuel cell system, and clean hydrogen is smoothly supplied to the anode side (anode such as air caused by hydrogen). Impurity purge at the side) and the OCV (Open Circuit Voltage) of the fuel cell is formed quickly.

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

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system having an air intake valve for preventing deterioration of a fuel cell and a method for preventing deterioration of a fuel cell using an air intake valve. The main point is to quickly remove residual hydrogen on the anode side by using a valve so that deterioration of the fuel cell can be prevented.

In the present invention, when the fuel cell system is shut down, the air is sucked in and at the same time, the hydrogen remaining on the anode side is quickly discharged to the outside by the sucked air so that the air is distributed without hydrogen on the anode side. Is prevented from being deteriorated while being exchanged with the cathode side oxygen through the electrolyte membrane.

In addition, impurities of the air and fuel cell anode supplied for removing residual hydrogen are quickly removed through hydrogen purge at the start of the fuel cell system, and clean hydrogen is smoothly supplied to the anode side (anode such as air caused by hydrogen). Impurity purge at the side) and the OCV (Open Circuit Voltage) of the fuel cell is formed quickly.

In this way, by using the recirculation blower and the air intake valve, the anode side is purged with intake air when the system is shut down, and when the system is started, residual impurities such as air are quickly removed through the recirculation blower and hydrogen purge. .

This invention will be described in more detail with reference to the following drawings.

1 is a view showing the configuration of a fuel cell system according to the present invention, FIG. 2 is a view showing an air purge state for removing residual hydrogen when the fuel cell system is shut down, and FIG. A diagram showing a hydrogen purge state for the.

4 and 5 are flowcharts illustrating a process of removing residual hydrogen and impurities according to the present invention, FIG. 4 is a flowchart illustrating a process of removing residual hydrogen at system shutdown, and FIG. 5 is a process of removing impurities at system startup. Flowchart.

First, referring to FIG. 1, a hydrogen supply device 110 and a fuel cell stack 120 are illustrated in a fuel cell vehicle, and in the present invention, residual hydrogen and Impurity removal is performed, but an air suction line 115a branched from the recycle line 115 in front of the hydrogen recycle blower 117 and an air suction valve 119 installed in the air suction line 115a are added.

As is well known, the hydrogen supply device 110 includes a hydrogen tank 111, a high pressure regulator 112 and a low pressure regulator 114, and a hydrogen supply valve 113 to supply hydrogen to the fuel cell stack 120. The high pressure hydrogen of the hydrogen tank 111 is reduced in the high pressure and low pressure regulators 112 and 114 to a prescribed pressure required by the fuel cell stack 120, and then supplied to the anode (hydrogen electrode) of the fuel cell stack 120.

In addition, the hydrogen recycling apparatus for recycling the remaining unreacted hydrogen back to the anode used in the anode of the stack 120 to increase the utilization of hydrogen is a hydrogen recycling line 115 connecting the front and rear ends of the anode side of the fuel cell stack 120. ), A hydrogen recycle blower 117 installed in the hydrogen recycle line 115, and a recycle line shutoff valve 116 installed at an inlet side of the hydrogen recycle line 115.

In addition, a hydrogen purge valve 118 for purging hydrogen at the anode side is installed at the rear end of the fuel cell stack 120, and in the present invention, as described above, the air suction line 115a and the hydrogen recirculation blower 117 are provided. An air suction valve 119 is added.

In the above configuration, an electronic valve such as a solenoid valve is used as each valve, and the valve controller 132 controls the driving of each valve, and the driving of the hydrogen recirculation blower 117 is performed by the fuel cell system controller 131. Will control. The valve controller 132 controls not only the existing valve but also the driving of the air intake valve 119 newly added in the present invention. The valve controller 132 receives power from the fuel cell system controller 131 which is an upper controller and supplies power to the valve. To control valve operation.

In the illustrated example, the valve controller 132 and the fuel cell system controller 131 are cooperatively controlled to control each valve and the hydrogen recirculation blower 117 for removing residual hydrogen and impurities, but this is a typical example. In addition, the valve controller and the fuel cell system controller may be integrated into one controller capable of recognizing system shutdown and start-up for implementing the present invention.

Hereinafter, the operating state of the system according to the present invention will be described.

First, in order to prevent deterioration of the stack 120 during the system shutdown, residual hydrogen on the anode side is removed by sucking external air using a hydrogen recycle blower 117. At this time, the valve controller 132 closes the hydrogen supply valve 113 and the recirculation line shutoff valve 116 according to the command of the fuel cell system controller 131 in a state in which the load connected to the fuel cell is all shut off, and the hydrogen purge valve ( 118 and the air suction valve 119 are opened, and the fuel cell system controller 131 drives the hydrogen recirculation blower 117.

Accordingly, as shown in FIG. 2, external air sucked through the air intake valve 119 is discharged through the hydrogen purge valve 118 via the hydrogen recirculation blower 117 and the fuel cell stack 120, and eventually Intake air purges the inside of the anode to remove residual hydrogen and ensure that only air is present at the anode. As such, if only the air is uniformly present in the cathode and the anode of the fuel cell, deterioration of the fuel cell can be prevented in the stationary state of the system for a long time.

After the system starts, the valve controller 132 opens the hydrogen supply valve 113, the hydrogen purge valve 118, and the recirculation line valve to effectively discharge the remaining air on the anode side and fill the pure hydrogen quickly. 119 is closed, and then the fuel cell system controller 131 drives the hydrogen recycle blower 117.

Accordingly, as shown in FIG. 3, while the hydrogen supplied by the hydrogen supply device 110 is discharged through the hydrogen purge valve 118, a portion of the hydrogen is circulated along the hydrogen recycle line 115, and eventually hydrogen The gas can purge the anode side (including the anode line) to discharge impurities such as remaining air to the outside.

4 and 5 show a specific embodiment for achieving the object of the invention at the time of system shutdown and start-up, the hydrogen recycle blower 117 is turned off during the system shutdown, after which the hydrogen recycle blower 117 is rotated When the number is lower than the reference speed, the hydrogen supply valve 113 and the recirculation line shutoff valve 116 are closed, the hydrogen purge valve 118 and the air suction valve 119 are opened, and then the hydrogen recirculation blower 117 ) Is driven for a predetermined time α.

Here, when closing the recirculation line shut-off valve 116 in a state in which the hydrogen recirculation blower 117 is greater than or equal to the reference rotation speed during system shutdown, the blower may be damaged while the vacuum pressure is applied to the rear end of the blower. It is desirable to close the recirculation line shutoff valve 116 when less than a few. However, when the air intake valve 119 is opened prior to the recirculation line shutoff valve 116, the recirculation line shutoff valve may be closed regardless of the number of revolutions of the blower.

When a predetermined time elapses after driving the hydrogen recirculation blower 117, the hydrogen recirculation blower is stopped, and all other valves except the recirculation line shutoff valve 116, which are normally open valves, are closed.

In addition, when the system starts, the hydrogen supply valve 113 and the hydrogen purge valve 118 are opened while the air intake valve 119 and the recirculation line shutoff valve 116 are shut off, and after a predetermined time β, the recirculation line is opened. Open the shutoff valve 116. At the same time, the hydrogen recirculation blower 117 is driven and the hydrogen purge valve 118 is shut off after a predetermined time (γ) has elapsed.

Here, it is preferable to open the recirculation line shutoff valve 116 after a predetermined time elapses. The reason for closing the recirculation line shutoff valve 116 at the initial stage of starting is that the hydrogen fuel cell is opened in the state where the hydrogen supply valve 113 is opened. This is to prevent the problem that impurities in the stack are not removed smoothly by hydrogen flowing out to the recirculation line 115 which is relatively low pressure in the early stage of purging the anode of the hydrogen purge valve. 118) to open the recirculation line at some point.

Thus, in the present invention, by controlling the operation of the valve and the hydrogen recirculation blower, it is possible to prevent the deterioration of the stack by removing residual hydrogen on the anode side with external air during shutdown of the fuel cell system. By removing impurities such as air on the anode side, clean hydrogen can be smoothly supplied.

1 is a view showing the configuration of a fuel cell system according to the present invention;

2 is a view showing an air purge state for removing residual hydrogen at shutdown of a fuel cell system in the present invention;

3 is a view showing a hydrogen purge state for removing impurities at the start of the fuel cell system in the present invention,

4 and 5 are flowcharts illustrating a process of removing residual hydrogen and impurities according to the present invention, FIG. 4 is a flowchart illustrating a process of removing residual hydrogen at system shutdown, and FIG. 5 is a flowchart illustrating a process of removing impurities at system startup.

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

110: hydrogen supply device 111: hydrogen tank

113: hydrogen supply valve 115: hydrogen recirculation line

116: recirculation line shutoff valve 117: hydrogen recirculation blower

118: hydrogen purge valve 119: air suction valve

120: fuel cell stack

Claims (7)

In a fuel cell system comprising a hydrogen recycle blower (117), a recycle line shutoff valve (116) and a hydrogen purge valve (118), An air suction line 115a branched from the hydrogen recycle line 115 at the front end of the hydrogen recycle blower 117 and an air suction valve 119 installed therein, The controller allows each of the valves and the hydrogen recycle blower so that external air sucked into the air intake line 115a by the hydrogen recycle blower 117 purges the fuel cell anode side to remove residual hydrogen during shutdown of the fuel cell system. A fuel cell system having an air intake valve for preventing deterioration of a fuel cell, characterized by controlling (117). The method according to claim 1, The controller, In order to remove residual hydrogen, while the hydrogen supply of the fuel cell stack 120 is cut off, the recirculation line shutoff valve 116 is closed and the air suction valve 119 and the hydrogen purge valve 118 are opened. A fuel cell system having an air intake valve for preventing deterioration of a fuel cell, which drives a hydrogen recycle blower 117 for a time period. The method according to claim 1, The controller, In order to remove the air and impurities supplied when the residual hydrogen is removed from the fuel cell anode, the hydrogen purge valve 118 is opened while the hydrogen is supplied to the fuel cell stack 120 at the start of the fuel cell system. A fuel cell system having an air intake valve for preventing deterioration of a fuel cell, wherein the hydrogen recirculation blower is driven after closing the valve 119 and the recirculation line shutoff valve 116. When the fuel cell system is shut down, close the recirculation line shutoff valve at the inlet side of the hydrogen recirculation line with the hydrogen supply of the fuel cell stack shut off. Open the air purge valve in front of the hydrogen purge valve and the hydrogen recirculation blower, and then drive the hydrogen recirculation blower for a certain time. A method of preventing deterioration of a fuel cell using an air intake valve, wherein external air sucked from the air intake valve by the hydrogen recirculation blower purges the fuel cell anode side. The method according to claim 4, The recirculation line shutoff valve, A method for preventing deterioration of a fuel cell using an air intake valve, characterized in that the hydrogen recycling blower is turned off when the fuel cell system is shut down when the rotation speed of the hydrogen recycling blower is less than the reference rotational speed. The method according to claim 4, To remove the air and impurities supplied when removing residual hydrogen from the fuel cell anode, close the air inlet valve and close the hydrogen purge valve and recirculation line shutoff valve while hydrogen is supplied to the fuel cell stack at the start of the fuel cell system. A method of preventing deterioration of a fuel cell using an air intake valve, wherein the hydrogen purge is performed by driving a hydrogen recirculation blower after opening. The method according to claim 6, The recirculation line shutoff valve is a method for preventing deterioration of a fuel cell using an air intake valve, characterized in that the air intake valve closes and the hydrogen purge valve opens after a certain time.

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