JP3240785B2 - Internal reforming fuel cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten carbonate type internal reforming fuel cell in which a reformer for reforming a fuel gas into an anode gas mainly composed of hydrogen gas is incorporated in the fuel cell.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have features that are not found in conventional power generation equipment, such as high efficiency and little adverse effect on the environment, and have attracted attention as power generation systems following hydro, thermal and nuclear power. Are being researched and developed in various countries around the world.

In particular, in a power generation facility using a molten carbonate fuel cell using natural gas as a fuel, as shown in FIG. 4, a reformer for reforming a fuel gas 1 such as natural gas into an anode gas 2 containing hydrogen. And a fuel cell 12 for generating electricity from the anode gas 2 and the cathode gas 3 containing oxygen. The anode gas 2 produced by the reformer 10 is supplied to the fuel cell 12 and After consuming a large part (for example, 80%) of the gas in the fuel cell 12, the gas is supplied to the combustion chamber Co of the reformer 10 as the anode exhaust gas 4. The fuel gas 1 is preheated by the fuel preheater 11 and enters the reforming chamber Re of the reformer 10. In the reformer 10, combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas 4 are burned in the combustion chamber Co, and the reforming chamber Re is heated by the high-temperature combustion gas to reform the fuel flowing inside. .

[0004] The combustion exhaust gas 5 that has exited the reforming chamber 10 is heat-recovered by an air preheater 13, water is removed by a condenser 14 and a steam-water separator 15, and the turbine compressor (power recovery device 16)
The mixed gas is heated by the air preheater 13 and merges with the cathode gas 3. Thereby, the carbon dioxide generated on the anode side of the cell enters the cathode gas 3 for the fuel cell via the combustion exhaust gas 5, and
Carbon dioxide necessary for the cathode reaction of the fuel cell 12 is supplied to the cathode side C. A part of the cathode gas 3 reacts in the fuel cell to form a cathode exhaust gas 7, a part of which is recirculated to the cathode inlet side, and a part of which is supplied to the combustion chamber Co of the reformer 10 and the anode exhaust gas 4. Is burned, and the remainder is supplied to the power recovery device 16 to recover the pressure, and is discharged out of the system. In the figure, 12a is a storage container of the fuel cell 12, and 8 is a purge gas supplied to the storage container 12a.

In the reforming chamber 10, the reforming chamber Re is heated by the high-temperature combustion gas in the combustion chamber Co in order to reform the fuel gas 1 flowing inside. On the other hand, since the operation of the fuel cell 12 involves an exothermic effect, an internal reforming fuel cell in which the reformer 10 and the fuel cell 12 are integrated by directly filling the reforming catalyst into the anode A of the fuel cell 12 is used. I have. In such an internal reforming fuel cell, since the hydrogen generated by the reforming is immediately consumed in the fuel cell, the temperature of the reformer (for example, 800 ° C. or higher)
Lower operating temperature of fuel cell (about 600-700 ° C)
Also has the advantage of a high reforming rate.

FIG. 5 is a schematic view of such an internal reforming fuel cell. The fuel cell 12 includes an anode electrode 21 and a cathode electrode 22 with an electrolyte plate 20 interposed therebetween.
The gas seal between the fuel cell 12 and the cathode side C depends on the electrolyte wetting (surface tension) at the operating temperature of the fuel cell 12 (about 600 to 700 ° C.) (referred to as a wet seal).
The fuel cells 12 are stacked in multiple stages with a separator 23 interposed therebetween. An anode gas flow channel 23 a for supplying anode gas is provided on a surface in contact with the anode electrode 21, and a cathode gas 3 is provided on a surface in contact with the cathode electrode 22. A supply cathode gas flow path 23b is provided. The anode gas flow path 23a is filled with a reforming catalyst 24. The fuel gas 1 is reformed into hydrogen gas by the reforming catalyst 24 heated by the fuel cell 12, and supplied to the anode electrode 21 to perform a cell reaction. .

[0007]

Since the reforming catalyst 24 is in direct contact with the anode electrode 21, the reforming catalyst is contaminated and deteriorated by the wetting by the electrolyte. In the vicinity of the fuel gas input, a fuel gas that hardly comes into contact with the reforming catalyst is supplied to the anode electrode 21, and a gas flowing along the surface of the anode electrode 21 hardly comes into contact with the reforming catalyst 24.
As described above, since the fuel gas that does not sufficiently contact the reforming catalyst 24 is not reformed into hydrogen gas, the efficiency of the reformer is reduced, and the output of the fuel cell is reduced.

The present invention has been made in view of the above-mentioned problems, and provides an internal reforming fuel cell in which the reforming catalyst is prevented from being contaminated by the electrolyte and the contact of the fuel gas with the reforming catalyst is improved. The purpose is to:

[0009]

According to the present invention, an anode gas (2) containing hydrogen is supplied to an anode electrode (21) , and a cathode gas (3) containing oxygen is supplied to a cathode. an electrode fuel cell (12) for generating electricity by supplying (22) comprises a separator (23) for separating between the fuel cell (12), on the side in contact with the anode electrode (21) of the separator (23) , Fuel cell (12)
To reform the fuel gas (1) with the heat transferred from
An anode gas flow path (23a) is formed, and a cathode electrode is formed.
On the side in contact with (22), a cathode gas flow path (23b)
Is formed in the anode gas flow path (23a).
A catalyst chamber (25) surrounded by a surrounding wall and filled with a reforming catalyst (24) flows through the anode gas flow path (23a).
Direction and axial direction are orthogonal to each other, and each catalyst chamber
(25) is a space having substantially the same cross-sectional shape as the catalyst chamber (25).
(26) and consists arranged alternately configured, the catalyst chamber
(25) is an enclosure for blocking the anode gas flow path (23a)
(27) , wherein the surrounding wall (27) is provided with a plurality of openings (28) constituting a flow path .

An opening (28) provided in the surrounding wall (27 ) for blocking the anode gas flow path (23a) is arranged at a lower position away from the vicinity of the anode electrode (21) .

[0011]

In the structure of the present invention, the catalyst chamber (25) filled with the reforming catalyst (24 ) is provided in the anode gas flow path (23a).
It is arranged so that the flow direction and the axial direction are orthogonal to each other.
The medium chamber (25) is an empty space having substantially the same cross-sectional shape as the catalyst chamber (25).
During (26) has a arranged alternately configured and, in the catalyst chamber (25) enclosing wall that blocks (27) is provided the anode gas flow path (23a), in the enclosure (27) flow path a plurality of openings (28) is provided which constitutes the. Since the reforming catalyst (24) is filled in the catalyst chamber (25) , there is little possibility that the reforming catalyst comes into contact with the electrolyte, and deterioration is prevented. The opening (2 ) provided in the surrounding wall (27) of the catalyst chamber (25)
Since the fuel gas (1) and the reformed hydrogen gas flow through 8) , the opening of the fuel gas (1) is provided by providing an opening (28) at a position sufficiently in contact with the reforming catalyst (24). It is no longer supplied to the anode electrode (21) without being modified.

The upper part of the catalyst chamber (25) , that is, in the vicinity of the surface of the anode (21), is provided with a reforming catalyst (24).
Are not sufficiently filled and gaps are likely to occur. Therefore, by disposing the opening (28) provided in the surrounding wall (27 ) for blocking the anode gas flow path (23a) below the vicinity of the surface of the anode electrode (21) , the fuel gas (1) allows the reforming catalyst ( 24) , and the reforming efficiency is improved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of the configuration of the embodiment, and FIG.
FIG. 3 is a three-dimensional exploded view of the embodiment, and FIG. 3 is a sectional view taken along line XX of FIG. In FIG. 1, the same reference numerals as those in FIG. 4 indicate those having the same functions.

A fuel cell 12 is constituted by an anode electrode 21 and a cathode electrode 22 with an electrolyte plate 20 interposed therebetween, and the fuel cells 12 are stacked with a separator 23 interposed therebetween. An anode gas passage 23a is formed on the side of the separator 23 that contacts the anode electrode 21, and a cathode gas passage 23b is formed on the side of the separator 23 that contacts the cathode electrode 22. Inside the anode gas flow channel 23a, a rectangular column-shaped catalyst chamber 25 which is surrounded by a surrounding wall and is filled with a reforming catalyst 24 is disposed so that the flow direction of the anode gas flow channel 23a is orthogonal to the axial direction. ing. The surrounding wall of the catalyst chamber 25 is made of corrosion-resistant stainless steel or the like. Each of the catalyst chambers 25 is alternately arranged with a space 26 having substantially the same cross-sectional shape as the catalyst chamber 25. In this space 26, the anode gas flow path 23a is in contact with the anode electrode 21, and the reformed hydrogen gas is supplied to the anode electrode 2
1 is supplied. As shown in FIG. 3, a large number of openings 28 are provided in the surrounding wall 27 of the catalyst chamber 25 orthogonal to the flow direction of the anode gas flow path 23a to form a flow path. The opening 28 is provided at a height less than a certain distance from the upper portion near the anode electrode 21 (that is, below the vicinity of the anode electrode 21 surface) . This is because the vicinity of the ceiling wall of the catalyst chamber 25 may not be sufficiently filled with the reforming catalyst 24 and the fuel gas 1 does not pass therethrough. Note that the openings 28 are provided from both sides and from a position somewhat away from the lower side. One surface of the cathode gas flow path 23b is in contact with the cathode electrode 22, and a flow path is formed in the flow direction of the cathode gas.

Next, the operation will be described. Fuel cell 12
, The reforming catalyst 24 in the catalyst chamber 25 is heated to the battery operating temperature (about 600 to 700 ° C.). When the fuel gas 1 enters, a certain amount of the fuel gas is reformed in the first catalyst chamber 25 to become a reformed gas containing hydrogen as a main component, and is supplied to the anode electrode 21 in the space 26. Next catalyst chamber 25
The anode exhaust gas generated by the cell reaction between the fuel gas 1, the reformed gas, and the fuel enters the fuel gas 1, the fuel gas 1 becomes the reformed gas, and the reformed gas and the anode exhaust gas come out to the next space 26 as they are, It is supplied to the anode electrode 21. Thereafter, similarly, each time the fuel gas 1 passes through each catalyst chamber 25, the fuel gas 1 becomes a reformed gas and decreases, and the anode exhaust gas increases.
The reformed gas also decreases as it approaches the final catalyst chamber 25. The gas leaving the final catalyst chamber 25 is mostly the anode exhaust gas 4 and contains some reformed gas. The anode exhaust gas 4 containing the reformed gas is burned in the combustion chamber Co. This combustion exhaust gas contains carbon dioxide contained in the anode exhaust gas 4 and carbon dioxide generated by combustion.

A part of the cathode exhaust gas 7 and the combustion exhaust gas discharged from the combustion chamber Co are mixed with the air 6 to become the cathode gas 3, which is supplied to the cathode gas passage 23 b by the high-temperature blower 18. The cathode gas 3 contains oxygen contained in the air 6 and carbon dioxide contained in the combustion exhaust gas, and performs a cathode reaction.

[0017]

As is apparent from the above description, in the present invention, the catalyst chamber in contact with the anode electrode is provided alternately with the space along the flow path, and the reforming catalyst is separated from the electrolyte by the surrounding wall of the catalyst chamber. Therefore, deterioration of the reforming catalyst can be prevented. Further, by providing a plurality of openings in the surrounding wall of the catalyst chamber and setting the opening positions so that the reforming catalyst and the fuel gas are in sufficient contact, the amount of the fuel gas directly supplied to the anode electrode without reforming is reduced. are doing. In addition, since the fuel gas carries out the cell reaction while passing through the multi-stage catalyst layer, each reaction becomes uniform, and the temperature difference between the inlet and the outlet of the fuel cell becomes small due to a synergistic effect with the endothermic effect by the reforming reaction, The power of the high-temperature blower for cathode recycling is extremely small, and the efficiency of the fuel cell plant can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an internal reforming fuel cell of an example.

FIG. 2 is a three-dimensional exploded view of the internal reforming fuel cell of the embodiment.

FIG. 3 is a view showing the arrangement of openings in the XX cross-sectional view of FIG. 1;

FIG. 4 is an overall structural diagram of a power generation facility using a conventional molten carbonate fuel cell.

FIG. 5 is a schematic view of a conventional internal reforming fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel gas 2 Anode gas 3 Cathode gas 4 Anode exhaust gas 5 Combustion exhaust gas 6 Air 7 Cathode exhaust gas 12 Fuel cell 18 High temperature blower 20 Electrolyte plate 21 Anode electrode 22 Cathode electrode 23 Separator 23a Anode gas channel 23b Cathode gas channel 24 Reforming Catalyst 25 Catalyst chamber 26 Space 27 Enclosure wall 28 Opening

Claims (2)

(57) [Claims] An anode gas (2) containing hydrogen is supplied to an anode electrode (21) and a cathode gas containing oxygen is supplied.
(3) and a fuel cell (12) for generating electricity is supplied to the cathode electrode (22) comprises a separator (23) for separating between the fuel cell (12), said anode electrode (21) of the separator (23) The anode gas flow path (23 ) is provided on the side in contact with the anode gas flow path for reforming the fuel gas (1) with heat transferred from the fuel cell (12).
a) is formed and on the side in contact with the cathode electrode (22)
Is formed with a cathode gas flow path (23b ), and a surrounding wall is formed in the anode gas flow path (23a).
Rarely, a catalyst chamber (2 ) filled with a reforming catalyst (24)
5) The flow direction and the axial direction of the anode gas flow path (23a)
Are arranged at right angles, and each catalyst chamber (25) is
URN catalyst chamber consists configurations are disposed alternately with the space (26) of the same cross-sectional shape (25), the catalyst chamber (25) has a surrounding wall (27) for interrupting the anode gas flow path (23a), An internal reforming fuel cell, wherein the surrounding wall (27) is provided with a plurality of openings (28) constituting a flow path. 2. An opening (28) provided in the surrounding wall (27 ) for blocking the anode gas flow path (23a) is arranged at a lower position away from the vicinity of the surface of the anode electrode (21). The internal reforming fuel cell according to claim 1, wherein