KR101322680B1 - Gas-liquid separator for cascade type fuel cell - Google Patents

Abstract

The present invention relates to a gas-liquid separator for use in a fuel cell, and more particularly, to a gas-liquid separator for a fuel cell in which a stack has a cascade structure.
The present invention comprises a primary separation chamber for receiving and discharging the residual gas mixed with the condensate discharged from the discharge manifold of the fuel cell stack to the central portion to separate and discharge the gas and liquid to the gas outlet and the liquid outlet respectively provided in the upper and lower parts; A secondary storage chamber for receiving and storing liquid discharged from the liquid outlet of the primary separation chamber; A humidifying water supply pipe for supplying a liquid stored in the secondary storage chamber to a humidifier; And a gas discharge pipe for discharging the residual gas separated from the secondary storage chamber.

Description

Gas-liquid separator for cascade type fuel cell {GAS-LIQUID SEPARATOR FOR CASCADE TYPE FUEL CELL}

The present invention relates to a gas-liquid separator for use in a fuel cell, and more particularly, to a gas-liquid separator for a fuel cell in which the stack has a cascade structure.

In general, a device for directly converting energy contained in a fuel into electrical energy. A fuel cell includes a pair of electrodes with an electrolyte interposed therebetween, and hydrogen (or fuel gas containing hydrogen) on the surface of one electrode. By contacting and contacting oxygen (or oxygen-containing oxidizing gas) to the surface of the other electrode, it is a method of using the inter-electrode electrical energy generated by the electrochemical reaction generated between the pair of electrodes.

These fuel cells are classified in various ways according to the type of electrolyte used, and polymer electrolyte membrane fuel cells (PEMFC) operate at a relatively low temperature of 100 ° C or lower than other fuel cells. In addition, it has fast start-up and response characteristics, and is widely used for mobile power supplies for automobiles, distributed power supplies for homes and public buildings, and small power supplies for electronic devices.

The stack assembly applied to such a PEMFC is usually a membrane made of a polymer electrolyte membrane between a bipolar plate (referred to as a separator) that forms a cathode for supplying hydrogen fuel and an anode for supplying oxygen. The unit cell in which the electrode assembly (MEA; Membrane Electrode Assembly) is located is configured to be stacked in multiple layers.

Since the output of the electrical energy of such a fuel cell varies with various driving conditions such as gas pressure, battery temperature, and gas utilization rate, the driving conditions thereof are appropriately controlled in various ways to increase the output of the fuel cell.

When operating such a fuel cell, the fuel supplied to the stack must be supplied at least "1" (which is greater than the design value), so that the output of the stack can be "1 (which corresponds to the design value)" In order to obtain the design output regardless of the design characteristics between the fuel supply and the output of the fuel cell, the fuel supply amount supplied to the fuel cell must be supplied with more fuel than the design value.

As a result, a method of achieving the same design output while matching the fuel supply of the fuel cell device with the design value is being developed.

The cascade fuel cell stack divides the fuel cell stack into a plurality of stages, and supplies residual gas discharged from the front stage to the reactive gas of the rear stage to improve gas utilization efficiency.

When the fuel cell stack is a cascade type, it is essential to install a gas-liquid separator to remove condensate generated by the reaction in the existing stage in supplying and recycling the remaining gas used in the front stage to the next stage. The condensed water separated from the gas-liquid separator is supplied to the humidifier to be used as humidifier and then discharged to the outside.

During start-up of the fuel cell module, the fuel gas and the oxidizing gas supplied to the fuel cell stack become non-humidified during the generation of condensed water to be supplied to the humidified water by the electrochemical reaction, which adversely affects the performance and durability of the fuel cell. Will be given.

An object of the present invention is to enable the supply of humidified water to the humidifier immediately from the gas-liquid separator at the start of the cascade fuel cell.

Another object of the present invention is to separate and remove traces of gas that can be discharged with condensate.

Another object of the present invention is to reduce the size of the gas-liquid separator to minimize the effect on tilting.

In order to achieve the above object, the present invention provides a residual gas mixed with condensate discharged from the discharge manifold of the fuel cell stack to a central portion, and separates and discharges gas and liquid into gas and liquid outlets respectively provided at upper and lower portions thereof. Primary separation chamber; A secondary storage chamber for receiving and storing liquid discharged from the liquid outlet of the primary separation chamber; A humidifying water supply pipe for supplying a liquid stored in the secondary storage chamber to a humidifier; And a gas discharge pipe for discharging the residual gas separated from the secondary storage chamber.

At this time, the ratio of the liquid storage amount of the primary separation chamber and the liquid storage amount of the secondary storage chamber is preferably in the range of 1: 3 to 1: 5.

In addition, the gas outlet of the primary separation chamber is connected to the gas recovery pipe connected to the supply manifold of the fuel cell stack,

The liquid supplied to the humidifier is supplied using a pressure difference between the secondary storage chamber and the humidifier, and may be provided with a pump for pumping the liquid on the humidifying water supply pipe if necessary.

The primary separation chamber preferably has an aspect ratio of 3 to 6, the height divided by the square root of the horizontal cross-sectional area.

The primary separation chamber may further include a water level sensor for measuring the height of the gas-liquid boundary at the central portion,

The secondary storage chamber is preferably provided on the bottom of the humidifier, the secondary storage chamber is more preferably provided with a shock absorbing plate having a shock absorbing function on the outer surface.

The present invention is provided with a storage chamber to sufficiently store the condensed water to be supplied to the humidifier at startup, the humidifier can be supplied to the humidifier immediately at the start of the fuel cell.

Therefore, reducing the supply of unhumidified gas at the beginning of fuel cell startup helps to improve the durability of the fuel cell stack and the humidifier.

In addition, since the gas-liquid separator according to the present invention is less affected by inclination, the gas-liquid separator has an effect that is very suitable for a fuel cell applied to a vehicle or a ship which experiences inclination of the driving environment.

1 is a conceptual diagram illustrating the basic principle of a gas-liquid separator;
2 is a configuration diagram showing a connection between a conventional gas-liquid separator, a fuel cell stack, and a humidifier;
Figure 3 is a block diagram showing the connection between the gas-liquid separator, the fuel cell stack and the humidifier according to an embodiment of the present invention.

Hereinafter, a gas liquid separator for a cascade type fuel cell according to the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to achieve them, will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Like reference numerals refer to like elements throughout the specification.

In the drawings, it is to be noted that the sizes of the constituent elements of the invention are exaggerated for clarity of description, and when it is described that any constituent element is present inside or connected to another constituent element, The element may be installed in contact with the other element, may be installed at a predetermined distance from the element, and may be provided with a third element for fixing or connecting the element to the other element, The description of the means may be omitted.

1 is a conceptual diagram illustrating the basic principle of a gas-liquid separator.

The gas-liquid separator 10 serves to separate and discharge the liquid and the gas by receiving the fluid in a two-phase mixed state in which the gas and the liquid are mixed. When the fluid in a mixed state of gas and liquid is stagnated, the liquid collects downward by gravity and the gas collects above the liquid.

The gas-liquid separator 10 has a tubular shape capable of accommodating a fluid, and receives a fluid in which a liquid and a gas are mixed in a central portion, discharges gas to an upper side, and discharges a liquid to a lower side.

In order for the gas-liquid separator 10 to operate normally, the liquid surface (gas-liquid boundary) inside the gas-liquid separator 10 should be located at the center of the gas-liquid separator 10. If the liquid level is too high, the liquid may be incorporated into the upper side where the gas should be discharged, and if the liquid level is too low, the gas may be mixed into the lower side where the liquid should be discharged.

To this end, the gas-liquid separator 10 is provided with one or more water level sensors 12 for sensing the water level of the liquid contained therein. In addition, the gas-liquid separator 10 is a control unit for controlling the opening and closing of the liquid flow rate control valve 24 and the liquid flow rate control valve 24 according to the water level detected by the water level sensor 12 to adjust the amount of liquid discharged It includes.

The control unit controls the opening and closing of the liquid flow control valve 24 so that the surface of the gas-liquid separator 10 detected by the water level sensor 12 maintains a constant range. For example, to lower the water level, the liquid flow control valve 24 is opened to discharge the liquid, and when the water level sensor 12 detects a certain level, the liquid flow control valve 24 is closed to stop the discharge of the liquid and supply the liquid. When the water level rises again, the liquid flow control valve 24 is operated in the same manner so that the internal water level is maintained in a constant range.

The provision of the gas flow control valve 22 is not essential, but optional.

By controlling the gas flow rate control valve 22 in a manner similar to the liquid flow rate control valve 24, it is possible to adjust the water level more quickly.

If the gas-liquid separator 10 is always maintained in a vertical state, there is no problem of mixing, but when the gas-liquid separator 10 is inclined, the water level of the liquid inside the gas-liquid separator 10 is changed accordingly, and the water level sensor ( 12) does not accurately detect the water level, the liquid is mixed with the gas discharged, or the gas is mixed with the liquid is discharged.

2 is a block diagram showing a connection relationship between a conventional gas-liquid separator, a fuel cell stack, and a humidifier.

As shown, the gas-liquid separator 120 is connected between the fuel cell stack 110 and the humidifier 130.

The gas-liquid separator 120 receives the condensed water and the off gas discharged through the discharge manifold of the fuel cell stack 110 to separate the fuel gas and the condensed water. Although the drawings indicate that the residual gas is a fuel gas, the residual gas may be a fuel gas or an oxidizing gas (air containing oxygen or oxygen). The gas-liquid separator of the present invention is irrelevant to the type of gas discharged together with the condensate, but hereinafter will be described based on the case where the residual gas is a fuel gas.

The separated fuel gas is returned to the supply manifold of the fuel cell stack 110 through the fuel gas recovery pipe 154, and the condensate is supplied to the humidifier 130 through the condensate water supply pipe 156.

At the end of the operation of the fuel cell stack, dry gas is supplied without a fuel cell chemical reaction in which water is generated to remove residual fuel gas, thereby depleting liquid inside the gas-liquid separator.

When the operation of the fuel cell is terminated and the operation is started again, condensate does not exist in the gas-liquid separator, so that the condensate is not smoothly supplied to the humidifier during the required amount of condensate. Therefore, the fuel cell stack operates at low humidification. Operation at low humidities adversely affects the durability of both the fuel cell stack and the humidifier.

3 is a diagram illustrating a connection relationship between a gas-liquid separator, a fuel cell stack, and a humidifier according to an exemplary embodiment of the present invention.

As shown, the gas-liquid separator according to the present invention is the primary separation chamber receiving the fuel gas mixed with the condensate from the discharge manifold of the fuel cell stack, and the secondary storage receiving the condensate separated from the primary separation chamber Chamber.

The present invention is to solve the problem of the lack of humidification water in the beginning by storing the liquid separated in the gas-liquid separator in the primary separation chamber 220 and the secondary storage chamber 240. In addition, the present invention is also divided into the primary separation chamber 220 and the secondary storage chamber by reducing the capacity of the primary separation chamber in which the actual separation of gas and liquid by reducing the effect of the tilting effect Bring.

The present invention divides the gas-liquid separator into a primary separation chamber 220 and a secondary storage chamber 240, wherein the liquid storage amount of the primary separation chamber 220 and the liquid storage amount of the secondary storage chamber 240 are determined. The ratio is characterized in that it ranges from 1: 3 to 1: 5.

Through this, it is possible to miniaturize the primary separation chamber 220 corresponding to the conventional gas-liquid separator, thereby reducing the effect of the tilt, and by increasing the residence time in the secondary storage chamber 240 fine bubbles It is possible to improve the performance of removing residual gas contained in the liquid.

If the ratio of the liquid storage amount of the primary separation chamber 220 and the secondary storage chamber 240 is less than 1: 3, the condensate stored in the secondary storage chamber 240 may not supply sufficient water to the humidifier at the beginning of the start-up. When the ratio of the liquid storage amount between the primary separation chamber 220 and the secondary storage chamber 240 exceeds 1: 5, the capacity of the primary separation chamber 220 may be too small to reduce the gas-liquid separation efficiency.

First, the primary separation chamber 220 will be described.

In the primary separation chamber 220, residual gas is stored in the upper space 222 and condensed water is stored in the lower space 224 based on the water surface (gas-liquid boundary) of the stored liquid. The remaining gas is discharged back to the supply manifold of the fuel cell stack 210 through the gas recovery pipe 254 and the condensate is sent to the secondary storage chamber 240 through the connection pipe 256.

Since the primary separation chamber 220 discharges the residual gas and the condensed water at a high flow rate, the condensed water often includes the residual gas in a fine bubble state. The primary separation chamber 220 is provided with a water level sensor therein, and discharges the liquid according to the water level detected therein.

Secondary storage chamber 240 has a longer residence time of the condensate than the primary separation chamber can separate the fine gas contained in the liquid. There is a risk of fire when the remaining gas is supplied to the humidifier in the condensate, the present invention has the effect of improving the fine residual gas removal rate by securing the condensate residence time in the secondary storage chamber (240).

The secondary storage chamber 240 receives condensate from the primary separation chamber 220, and separates a small amount of fuel gas included in the condensate, stores the condensate, and supplies the condensate to the humidifier.

The secondary storage chamber 240 supplies the condensate from which the fine gas is removed to the humidifier 230 through the humidifying water supply pipe 258. At this time, the supply of condensate may be made by a method of opening and closing a valve by a difference in pressure between the secondary storage chamber 240 and the humidifier 230. In this case, a separate pump may be provided, but the pump may be additionally pumped. The amount can also be controlled.

 Residual gas removed from the secondary storage chamber 240 is discharged to the outside through the gas discharge pipe (259).

The secondary storage chamber 240 is to store a certain amount of condensate during operation, the condensate stored in the secondary storage chamber 240 will remain as it is at the end of the operation. Therefore, due to the pressure difference between the humidifier and the gas-liquid separator present in the humidification water supply pipe 258 described above at the beginning of the fuel cell startup. Alternatively, by supplying a condensate stored in the secondary storage chamber 240 to the humidifier by operating a pump provided in addition, it is possible to solve the low-humidity problem of the initial start-up.

By allowing a certain amount of condensed water to be stored in the secondary storage chamber 240, the size of the primary separation chamber 220 may be reduced.

The primary separation chamber 220 separates liquid and gas in a vertical structure. In order to increase the flow rate of the stored liquid in the conventional case, the gas-liquid separator itself (the conventional gas-liquid separator consists of only the primary separation chamber of the present invention. There was no way to increase the size).

As the size of the gas-liquid separator increases, the inclination of the gas-liquid separator is further increased. In the case of the present invention, the required flow rate is stored in the secondary storage chamber 240 to store the required flow rate in the secondary storage chamber 240. The size can be reduced.

In the present invention, the aspect ratio of the primary separation chamber 220 is not greatly limited, but the greater the aspect ratio, the greater the effect of preventing the mixing of gas and liquid, and thus, gas-liquid separation can be performed smoothly even when tilted. In particular, when considering gas-liquid separation efficiency, it is preferable that it is the range of 3-6. If the aspect ratio is less than 3, the gas-liquid separation efficiency may be lowered. If the aspect ratio is more than 6, vortices may occur inside the gas-liquid separator, and the gas may be mixed with the liquid and discharged. Here, the aspect ratio means a value obtained by dividing the height of the separation chamber by the square root of the horizontal cross-sectional area of the separation chamber. For example, when the primary separation chamber has a square columnar shape of 20mm * 20mm * 70mm, the aspect ratio is 3.5. In the case of a rectangular columnar shape of 10mm * 40mm * 70mm, the aspect ratio is 3.5.

The installation position of the secondary storage chamber 240 may be attached to the humidifier 230, or may be installed in a position independent of the humidifier 230. In particular, when attached to the humidifier 230 It can be located on the top of the humidifier or on the side When positioned below the humidifier, the secondary storage chamber 240 may serve as a buffer means to mitigate the impact applied to the humidifier 230 is more preferable.

When the secondary storage chamber 240 is disposed below the humidifier 230, the secondary storage chamber 240 serves as a shock absorber that protects the humidifier 230 from an impact applied to the outside. In order to double this effect, the secondary storage chamber 240 may further include a buffer plate on the outer surface. The buffer plate may be made of a material such as natural rubber, synthetic rubber or foamed synthetic resin having an elastic material.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It will be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

210: fuel cell stack
220: primary separation chamber
240: secondary storage chamber
230: humidifier

Claims (8)

A primary separation chamber configured to receive residual gas mixed with condensate discharged from the discharge manifold of the fuel cell stack to a central portion and separate and discharge gas and liquid into gas and liquid outlets respectively provided at upper and lower portions thereof;
A secondary storage chamber for receiving and storing liquid discharged from the liquid outlet of the primary separation chamber;
A humidifying water supply pipe for supplying a liquid stored in the secondary storage chamber to a humidifier; And
And a gas discharge pipe for discharging the residual gas separated from the secondary storage chamber.
The primary separation chamber
A gas-liquid separator, characterized in that the aspect ratio of 3 to 6 divided by the square root of the horizontal cross-sectional area.
The method of claim 1,
The liquid storage amount of the primary separation chamber,
The ratio of the liquid storage amount of the secondary storage chamber is a gas-liquid separator, characterized in that the range of 1: 3 to 1: 5.
The method of claim 1,
The gas outlet of the primary separation chamber is
Gas-liquid separator, characterized in that connected to the gas recovery pipe connected to the supply manifold of the fuel cell stack.
The method of claim 1,
The liquid supplied to the humidifier is a gas-liquid separator, characterized in that the supply using the pressure difference between the secondary storage chamber and the humidifier.
delete The method of claim 1,
The primary separation chamber
Gas-liquid separator further comprises a water level sensor for measuring the height of the gas-liquid boundary in the center.
The method of claim 1,
The secondary storage chamber
Gas-liquid separator, characterized in that provided in the bottom portion of the humidifier.
The method of claim 7, wherein
The secondary storage chamber
Gas-liquid separator characterized in that it comprises a buffer plate having a shock absorbing function on the outer surface.

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