KR20070075040A - Fuel cell system having water supply apparatus for reformer - Google Patents

Abstract

A fuel cell system is provided to effectively condense, in a condenser, water vapor generated from a reforming step of hydrogen-containing fuel in a reformer and feed the condensed water to a reformer without operating a water pump, etc. The fuel cell system comprises: an electricity generator part(10) which generates electricity by an electrochemical reaction of hydrogen and oxygen; an air supply part which feeds oxygen-containing gas to the electricity generator part(10); a reformer(52) which produces reformed gas containing, as a main component, hydrogen to be supplied to the electricity generator part(10); and gas-liquid separators(62) which are provided between the electricity generator part(10) and the reformer(52) and capture water vapor to be generated from a production step of the reformed gas.

Description

FUEL CELL SYSTEM HAVING WATER SUPPLY APPARATUS FOR REFORMER}

1 is a schematic diagram of a fuel cell system according to the present invention;

Figure 2 is a schematic diagram showing a water supply device for a reformer according to the present invention;

3 is a cross-sectional view of the water storage tank of the reformer water supply device;

4 is a view showing the inner side of the water storage tank;

5 is a schematic view showing a water supply device of a conventional example;

6 is a configuration diagram showing a fuel cell system of a conventional example.

<Description of Symbols for Major Parts of Drawings>

10: electricity generating unit

20: fuel supply unit

30: air supply

50: reformer

60: gas-liquid separator

62: gas-liquid separation tank

64a, 64b, 64c, 64d: three phase valve

[Patent Document 1] Korean Patent Publication No. 2003-0073682

The present invention relates to a fuel cell system for generating electricity through an electrochemical reaction between hydrogen and oxygen, and more particularly to the gaseous water discharged from a reformer for reforming a hydrogen-containing fuel to generate a reformed gas mainly composed of hydrogen. It relates to a fuel cell system that can be recovered and recycled.

In general, a fuel cell system is a power generation system that generates electricity, and has an electricity generator that generates electricity by an electrochemical reaction between hydrogen and oxygen. The electricity generating unit has a structure in which a plurality of unit cells including a conductive polymer membrane having selective ion permeation characteristics and a cathode electrode and an anode electrode provided on both sides of the polymer membrane are stacked. Electricity is generated by chemical reaction between hydrogen and oxygen supplied to the anode electrode and the cathode electrode. Hydrogen to be supplied to the anode is obtained by reforming the hydrogen containing fuel in a reformer.

In the reformer, steam [H ₂ O (g)] is generated together with the reforming gas containing hydrogen as a main component in the process of reforming the hydrogen-containing fuel. In order to supply only the reformed gas to the electricity generator, the reformed gas and the steam discharged from the reformer must be separated. Referring to FIG. 5, the reformed gas discharged from the reformer (not shown) is introduced into the condenser 1 through the connection pipe 3 together with water vapor, and the water supplied from the water storage tank 2 to the condenser 1. [H ₂ O (l)] is stored. In the condenser 1, water vapor is condensed into water while the reformed gas is supplied to the electricity generator through the outlet.

If the water level stored in the condenser 1 is too high, the water of the condenser 1 is discharged to the water storage tank 2 by the operation of a water pump (not shown), while the water level of the condenser 1 is too high. If low, water is introduced from the water storage tank 2 by the operation of the water pump or the like.

At this time, the lower end of the connecting pipe (3) for introducing the reformed gas and water vapor into the condenser 1 is provided in a state of being deposited in the storage of the condenser 1, it is possible to effectively condense the water vapor. However, since a water pump or the like is used to flow water between the water storage tank 2 and the condenser 1, the volume of the fuel cell system increases and there is a problem of noise generation due to the operation of the water pump.

On the other hand, Korean Patent Publication No. 2003-0073682 (Patent Document 1) is provided with a secondary fuel tank and an auxiliary tank in the main fuel tank and the casting tank, respectively, when replacing the main fuel tank and the casting tank auxiliary fuel tank and auxiliary tank Disclosed is a fuel cell system (see FIG. 6) having a fuel supply device capable of continuously supplying fuel by continuously supplying fuel by using a fuel cell. However, in the fuel cell system, since a water pump is used to supply water from the main water tank or the auxiliary water tank, there is a problem of increasing the volume and generating noise due to the operation of the water pump.

The present invention has been proposed to solve the conventional problems as described above, while effectively condensing water vapor generated in the process of reforming hydrogen-containing fuel in the reformer in the condenser to supply the water of the condenser to the reformer without the operation of a water pump or the like. It is an object of the present invention to provide a fuel cell system having a water supply device.

Another object of the present invention is to provide a fuel cell system having a water supply device capable of supplying the reformer with the water stored in the water storage tank by using the vapor pressure of the compressed fuel.

In order to achieve the above object, according to the present invention, the fuel cell system includes an electricity generating unit for generating electricity by the electrochemical reaction of hydrogen and oxygen; An air supply unit supplying an oxygen-containing gas to the electricity generation unit; A reformer for generating a reformed gas mainly containing hydrogen to be supplied to the electricity generating unit; It is characterized by consisting of a gas-liquid separator provided between the electricity generating unit and the reformer to capture the steam generated in the process of generating the reformed gas.

The gas-liquid separator has at least two gas-liquid separation tanks, and the gas-liquid separation tank and the reformer are connected in fluid communication via a conduit having a branch pipe in which a three-phase valve is installed at the branch.

The fuel supply unit further includes a fuel supply unit for supplying hydrogen-containing fuel to the reformer, wherein the fuel supply unit is capable of fluid communication with the gas-liquid separation tank through a conduit having a branch pipe in which a three-phase valve is installed at the branch.

Water stored in the gas-liquid separation tank is supplied to the reformer through the water discharge pipe while hydrogen-containing fuel is introduced through the introduction pipe.

The gas-liquid separation tank is installed with a level sensor to detect the level of water stored.

Hereinafter, a fuel cell system according to the present invention will be described with reference to the accompanying drawings.

1 is a schematic view of a fuel cell system according to the present invention, FIG. 2 is a schematic view of a water supply device according to the present invention, FIG. 3 is a partial cutaway cross-sectional view of a water tank used in the water supply device of FIG. Is a view showing an inner side of the water tank.

Referring to FIG. 1, a fuel cell system includes an electricity generator 10 for generating electricity through an electrochemical reaction between hydrogen and an oxidant, and a reformer for supplying reformed gas mainly containing hydrogen to the electricity generator 10. 50, an air supply unit 30 for supplying an oxygen-containing gas to the electricity generating unit 10, and a fuel supply unit 20 in which hydrogen-containing fuel to be supplied to the reformer 50 is stored. Preferably, the fuel cell system further includes a gas-liquid separator 60 provided between the reformer 50 and the electricity generating unit 10 to separate the reformed gas and water vapor discharged from the reformer 50. Oxygen-containing gas supplied to the electricity generating unit 10 is made of pure oxygen or oxygen in the atmosphere stored in a separate storage means (not shown).

Part of the hydrogen-containing fuel stored in the fuel supply unit 20 flows into the reforming unit 52 of the reformer 50 as reformed fuel, and another portion of the hydrogen-containing fuel is a heat source of the reformer 50 as combustion fuel, that is, Flow into the combustion section 54. The oxygen-containing gas may be supplied from the air supply unit 30 to the combustion unit 54 so that the combustion fuel may be combusted in the combustion unit 54.

The reformer 50 may include a reforming reaction unit (not shown) for generating a reformed gas having a hydrogen component as a main component from the reformed fuel supplied from the fuel supply unit 20, and the reforming reaction unit may be in fluid communication with the reformed gas. It has a reforming part 52 including a CO removal part (not shown) which removes the carbon monoxide contained.

The reforming reaction unit is provided with a reforming catalyst (not shown). The reforming reaction unit reforms the reformed fuel using, but not limited to, steam reforming (SR), autothermal reforming (ATR), and partial oxidation (POX). The partial oxidation method and the autothermal reforming method have excellent response characteristics due to initial start-up and load variation, while the steam reforming method has an advantage in terms of hydrogen production efficiency.

In the steam reforming method, a reformed gas containing hydrogen as a main component is obtained by chemical reaction of reformed fuel and steam on the reforming catalyst, that is, endothermic reaction. In such a steam reforming method, a large amount of energy is required from the outside in order to perform the endothermic reaction, but since the reformed gas supply is stable, a relatively high concentration of hydrogen can be obtained.

Therefore, in the reforming unit 52, when the reforming reaction unit adopts, for example, a steam reforming system, a part of the hydrogen-containing fuel supplied from the fuel supply unit 20, that is, the reformed fuel is a gas liquid which will be described below. The reformed gas is reformed into hydrogen-rich reforming gas through steam reforming reaction in the reforming catalyst together with water supplied from the separator 60. During the reforming of the reformed fuel, steam [H ₂ O] is generated. In addition, the above-described reformed gas also generates trace amounts of carbon dioxide, methane gas and carbon monoxide in addition to hydrogen and water vapor. Carbon monoxide, in particular, poisons the platinum catalyst generally used as the electrode of the electricity generating unit 10, and thus, it is necessary to remove the performance of the fuel cell system.

The CO removal unit includes a water gas conversion unit (not shown) and a selective oxidation unit (not shown) in which a water gas conversion catalytic reaction and a selective oxidation catalytic reaction are respectively performed to remove carbon monoxide. The water gas conversion unit is provided with a shift catalyst (not shown), and the selective oxidation unit (not shown) is provided with an oxidation catalyst (not shown). The oxygen-containing air necessary for the selective oxidation reaction is supplied to the selective oxidation unit by the air supply unit 30.

In addition, the reformer 50 is provided with a combustion section 54 that burns another portion of the hydrogen-containing fuel supplied from the fuel supply section 20, that is, combustion fuel to generate thermal energy. The combustion section 54 is supplied with oxygen-containing air from the air supply section 30. The thermal energy generated in the combustion section 54 is supplied to the reforming reaction section and the CO removal section to heat the reforming reaction section and the CO removal section to the respective catalyst activation temperatures.

The reformed gas generated in the reforming unit 52 of the reformer 50 flows into the gas-liquid separator 60 together with the steam.

2 to 4, the gas-liquid separator 60 includes at least two gas-liquid separation tanks 62 in which water is stored. On the side of the gas-liquid separation tank 62, only the reformed gas is discharged from the inside of the gas-liquid separation tank 62 and the inflow pipe 62-2 through which the reformed gas and the steam are introduced from the reforming unit 52 of the reformer 50. A discharge pipe 62-3 is provided. The gas-liquid separation tank 62 is provided, for example, at its lower part with a water discharge pipe 62-4 for discharging water stored therein.

The inner surface of the gas-liquid separation tank 62 is provided with a water level detection sensor 66 for detecting the water level of the stored water. The water level detection sensor 66 is connected to the control unit (not shown) to enable signal transmission to provide the detected water level. The water level stored in the gas-liquid separation tank 62 is detected by the water level detection sensor 66 at the highest water level HL and the lowest water level LL.

At this time, the inlet pipe 62-2 is positioned above the highest water level HL. This is to prevent the storage water stored in the gas-liquid separation tank 62 to flow out to the reformer 50 through the inlet pipe 62-2 as described below.

The upper surface of the gas-liquid separation tank 62 is provided with an introduction pipe 62-1 which is connected to the fuel supply unit 20 to enable the introduction of hydrogen-containing fuel. The hydrogen-containing fuel introduced into the gas-liquid separation tank 62 functions to allow water stored in the gas-liquid separation tank 62 to flow out to the reformer 50 through the water discharge pipe 62-4.

In the gas-liquid separator 60, a first branch pipe is provided between the two gas-liquid separation tanks 62 so as to be in fluid communication with the reforming unit 52 of the reformer 50. The branch portion is provided with a first three-phase valve 64a. By the selective opening and closing operation of the first three-phase valve (64a), the reformed gas and water vapor flowing from the reforming unit 52 of the reformer 50 is selectively introduced into the gas-liquid separation tank.

In the gas-liquid separator 60, the two gas-liquid separation tanks 62 and the electricity generating unit 10 are connected by a third branch pipe, and the third three-phase valve 64c is connected to the branch of the third branch pipe. ) Is provided. By the selective opening and closing operation of the third three-phase valve 64c, the reformed gas discharged from the two gas-liquid separation tanks 62 is selectively introduced into the electricity generating unit 10.

In the gas-liquid separator 60, the two gas-liquid separation tanks 62 and the fuel supply unit 20 are connected by a second branch pipe, and a second three-phase valve 64b is connected to the branch of the second branch pipe. Is provided. The raw fuel supplied from the fuel supply unit 20 is selectively introduced into the two gas-liquid separation tanks 62 by the selective opening and closing operation of the second three-phase valve 64b.

In addition, in the gas-liquid separator 60, the water discharge pipe 62-4 and the reformer of the gas-liquid separation tank 62 so that water can be supplied from the gas-liquid separation tank 62 to the reforming reaction part of the reformer 50. The reforming portion 62 of 50 is connected by a fourth branch pipe, and the fourth three-phase valve 64d is provided at the base of the fourth branch pipe. As described below, when the water level stored in the gas-liquid separation tank 62 reaches the highest water level HL or when water is needed in the reforming reaction part of the reformer 50, the second three-phase valve 64b. Part of the hydrogen-containing fuel, that is, the raw fuel, is introduced into the at least one gas-liquid separation tank 62 through the second branch pipe by the opening and closing operation of the gas-liquid separation tank 62. The water stored in the) is discharged through the water discharge pipe 62-4 and supplied to the reformer 50 via the fourth branch pipe.

The three-phase valves 64a, 64b, 64c, and 64d described above are connected to the control unit to enable signal reception so that their operation is controlled.

For example, one gas-liquid separation tank 62, for example, a relatively low water level is stored in the first gas-liquid separation tank located on the left side in Figure 2 and another gas-liquid separation tank 62, for example For example, in a state in which water of a relatively high level is stored in the second gas-liquid separation tank located on the right side in FIG. 2, the control unit may include reformed gas and water vapor from the reforming unit 52 of the reformer 50. Maintaining the opening and closing state of the third three-phase valve 64c so that the reformed gas is supplied to the electricity generating unit 10 from the first gas-liquid separation tank while maintaining the opening and closing state of the first three-phase valve (64a) to flow only into the gas-liquid separation tank. do. At this time, the control unit while maintaining the opening and closing state of the second three-phase valve (64a) so that the hydrogen-containing fuel, that is, the raw fuel from the fuel supply unit 20 only flows into the second gas-liquid separation tank, the second gas-liquid separation tank The fourth three-phase valve 64d maintains the open / closed state so that water stored therefrom can be supplied to the reformer 50.

While the water stored in the second gas-liquid separation tank is supplied to the reformer 50 by the vapor pressure of the raw fuel supplied from the fuel supply unit 20, the reformed gas and the steam discharged from the reformer 50 are discharged. It enters the gas-liquid separation tank. At this time, in the first gas-liquid separation tank, water vapor is condensed and remains in the first gas-liquid separation tank as storage water, and the reformed gas is discharge pipe 62-3 provided to the first gas-liquid separation tank. It is supplied to the electricity generating unit 10 through.

As described above, since water vapor supplied from the reforming unit 52 of the reformer 50 is condensed in the gas-liquid separation tank 62, the storage level of water stored in the gas-liquid separation tank 62 is increased. At this time, when the highest water level of the stored water stored in the gas-liquid separation tank 62 is detected by the water level detection sensor 66, the control unit reforms the water stored in the gas-liquid separation tank 62 to the reforming reaction of the reformer 50. The open / close state of the three-phase valves 64a, 64b, 64c, and 64d is controlled to be supplied to the unit. This prevents water stored in the gas-liquid separation tank 62 from flowing out through the inlet pipe 62-2 and / or the discharge pipe 62-3 by the pressure of the raw fuel supplied from the fuel supply unit 20. To do this.

That is, when the open / close state of the three-phase valves 64a, 64b, and 64c is switched by the control unit, the raw fuel flows from the fuel supply unit 20 into the first gas-liquid separation tank, and from the reformer 52 of the reformer 50. The reformed gas and water vapor flow into the second gas-liquid separation tank. As a result, the water stored in the first gas-liquid separation tank is supplied to the reforming unit 52 of the reformer 50 through the water discharge pipe 62-4 by the vapor pressure of the raw fuel and to the second gas-liquid separation tank. The introduced reformed gas is supplied to the electricity generating unit 10 while the water vapor remains condensed in the second gas liquid separation tank.

On the other hand, the switching of the three-phase valves as described above is preferably made quickly. This is to minimize the amount of inflow of the raw fuel flowing into the electricity generating unit 10 during the opening and closing of the three-phase valve.

As described above, the oxygen-containing gas is passed through the air supply unit 30 while the reformed gas is supplied from the reformer 52 of the reformer 50 to the electricity generator 10 via the gas-liquid separator 60. When supplied to (10), the electricity is generated by the electrochemical reaction of hydrogen and oxygen made in the electricity generating section 10.

The foregoing is merely illustrative of preferred embodiments of the present invention and those skilled in the art to which the present invention pertains may make modifications and changes to the present invention without departing from the spirit and gist of the invention as set forth in the appended claims. It must be recognized.

According to the present invention, the reformed gas and the steam generated from the reformer of the reformer are alternately provided to at least two gas-liquid separation tanks of the gas-liquid separator so that the reformed gas is continuously supplied to the electricity generating unit and stored from the two gas-liquid separation tanks. By making the water supplied stably to the reformer of the reformer by the vapor pressure of the hydrogen-containing fuel, it is possible to smoothly manage the reformer and improve the power generation efficiency of the fuel cell.

Claims (14)

An electricity generator for generating electricity by an electrochemical reaction between hydrogen and oxygen; An air supply unit supplying an oxygen-containing gas to the electricity generation unit; A reformer for generating a reformed gas mainly containing hydrogen to be supplied to the electricity generating unit; And a gas-liquid separator provided between the electricity generating unit and the reformer to capture water vapor generated in the process of generating the reformed gas. The method of claim 1, Wherein said gas-liquid separator has at least two gas-liquid separation tanks connected to said reformer via a conduit having branching pipes and storing water therein. The method of claim 2, The side of the gas-liquid separation tank is a fuel cell system, characterized in that the inlet pipe which is connected to the inlet pipe to enable fluid inflow. The method of claim 3, The branch portion of the branch pipe is provided with a three-phase valve for connecting the gas-liquid separation tanks and the reformer to allow fluid inlet selectively. The method of claim 3, The inlet pipe is located in the upper portion of the maximum storage water level of the water stored in the gas-liquid separation tank. The method of claim 2, And a fuel supply unit for supplying hydrogen-containing fuel to be reformed to the reformer, wherein the fuel supply unit and the gas-liquid separation tank are connected through a conduit having a branch pipe to supply a portion of the hydrogen-containing fuel. Fuel cell system. The method of claim 6, The branch portion of the branch pipe is provided with a three-phase valve for connecting the gas-liquid separation tanks and the fuel supply portion to enable fluid inlet selectively. The method of claim 6, An upper portion of the gas-liquid separation tank is provided with an introduction pipe which is connected to the branch pipe to enable fluid communication. The method of claim 2, And the gas-liquid separation tanks and the electricity generating unit are connected through a conduit having a branch pipe so that the reformed gas is supplied. The method of claim 9, The branch portion of the branch pipe is provided with a three-phase valve for connecting the gas-liquid separation tanks and the electricity generating unit selectively in fluid communication. The method according to any one of claims 6 to 8, The lower portion of the gas-liquid separation tank is provided with a water discharge pipe for discharging the stored water, the water discharge pipe is characterized in that the fluid communication is connected to the reformer through a conduit having a branch pipe. The method of claim 11, The branch portion of the branch pipe is provided with a three-phase valve for connecting the gas-liquid separation tanks and the reformer selectively in fluid communication. The method of claim 11, And water stored in the gas-liquid separation tank is supplied to the reformer through the water discharge pipe while hydrogen-containing fuel is introduced through the introduction pipe. The method of claim 2, And a water level detection sensor provided inside the gas-liquid separation tank to detect the level of water stored.

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