JP2697461B2 - Internal reforming molten carbonate 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 an internal reforming molten carbonate fuel cell, and more particularly to an internal reforming molten carbonate fuel cell having improved structures of a stack and a reformer plate.

[0002]

2. Description of the Related Art Molten carbonate fuel cells use a gas mainly composed of hydrogen as a fuel gas. In large-scale molten carbonate fuel cell power generation, coal gas and natural gas are reformed by a reformer. It has been considered that the gas is used after being converted to a gas containing hydrogen as a main component. Even in relatively small-scale power generation, particularly in demand-based power generation (on-site power generation), since city gas (mainly methane) is used as a raw fuel, it must be reformed by a method such as steam reforming. . However, in the case of a small-scale power generation unit, installing a large-scale reformer separately from the power generation unit results in compactness, reduced system efficiency, and increased cost. For this reason, especially for on-site use, a so-called internal reforming method of reforming inside the battery is often used.

[0003] The internal reforming system utilizes the fact that the reaction heat of a fuel cell and the resistance heat of a battery member raise the temperature inside the cell, whereas the reforming reaction is an endothermic reaction.
In this method, a reforming reaction is performed inside the battery stack. Therefore, the internal reforming method does not require an external reforming device and also has the effect of cooling the battery. Such a method can directly supply city gas as fuel gas and can effectively use the heat generated by the battery, which is very advantageous in improving system efficiency, reducing costs, and improving compactness.

For this reason, two internal reforming systems, so-called direct internal reforming type and indirect internal reforming type, have been studied. The direct internal reforming type has a high efficiency, but has a problem that the catalyst is installed in the power generation part and the reforming catalyst is deteriorated due to seepage of the electrolyte or contact with the electrolyte vapor. In contrast, the indirect internal reforming type is somewhat disadvantageous in terms of thermal efficiency, but is advantageous in terms of life because the power generation part and the reforming part are separated.

On the other hand, there are an external manifold system and an internal manifold system as a gas supply system to each unit cell constituting the stack. The external manifold system has a structure in which an air chamber on the fuel side or oxidizer side of each unit cell is opened on the side of the stack, and a box-shaped external manifold is attached here to distribute gas to each unit cell. is there. On the other hand, the internal manifold system is a system in which a gas flow hole is provided in a peripheral portion of a unit cell, and gas is distributed to each unit cell from this hole (internal manifold).

In the case of performing indirect internal reforming by an external manifold system, for example, there is a system in which the inside of the manifold is divided into two as disclosed in JP-A-61-13576, but the manifold structure becomes complicated. It is difficult to reliably perform gas sealing. Further, in the external manifold system, since the movement of the electrolyte occurs through the manifold seal material, there is a disadvantage such that it is necessary to take a countermeasure.

On the other hand, as a method of performing internal reforming using an internal manifold type, as disclosed in Japanese Patent Application Laid-Open No. 3-105865, a reforming method in which the inside of a unit cell is divided into two and a reforming catalyst is filled on the upstream side of gas. There is a means of providing a region and reforming here. In addition, the inside of the reformer plate is bisected along the plane, one side is filled with a reforming catalyst, and the other side is filled with a combustion catalyst for burning unreacted fuel discharged from the fuel electrode, and this is a unit cell. It is also considered to be installed between them and reform by combustion heat and battery heat.

[0008]

However, in the case of performing internal reforming using an internal manifold type, in the former method of the above-mentioned conventional method, a part of the unit cell is applied to the reforming portion, so that the reforming section is not used. There was a problem in temperature uniformity, such as a decrease in temperature and an increase in temperature in one power generation unit. In the latter method, the combustion heat of the fuel exhaust gas can be used for the reforming reaction.
The unit cells in contact with the reforming side of the reformer plate are cooled, but the unit cells in contact with the catalytic combustion part are not preferable because the temperature rises conversely. Further, in this method, there is a problem that the stack structure becomes slightly complicated to supply fuel exhaust gas and combustion air. Therefore, an object of the present invention is to avoid these problems and to obtain an internal reforming molten carbonate fuel cell having a simple structure and capable of uniformly cooling the stack.

[0009]

In order to achieve this object, an internal reforming molten carbonate fuel cell according to the present invention comprises a stacked unit cell and a reformer plate for reforming a raw fuel, and a reformer plate for reforming the fuel cell. An internal manifold hole for supply of raw fuel gas and a manifold hole for fuel gas and an oxidizing gas provided in a state in which the fuel cell plate extends longitudinally. Each reformer plate is similar to a bipolar plate of a unit cell, and can supply and discharge only to the raw fuel gas supply internal manifold hole and the fuel gas manifold hole. the a, that have a simple structure to supply to each unit cell of the fuel gas obtained by reforming the supplied raw fuel gas together also function as a bipolar plate.

[0010] is found in the internal reformer plate is divided into three gas flow passages by a partition having a notch, the reforming catalyst is placed only in the central portion of the passage located in the center, the outer edge portion Provide an opening for the internal manifold hole for raw fuel gas supply,
The flow of the reformed fuel gas is reversed from the notch through the gas flow paths on both sides, and is supplied to each unit cell through the fuel manifold holes provided on both sides of the raw fuel gas supply internal manifold hole. The stack cooling is made uniform.

[0011]

With this configuration, the raw fuel gas supply internal manifold holes supply the raw fuel to the reformer plate, and supply the fuel gas reformed in the reformer plate to each unit cell. The reformer plate itself that acts as a bipolar plate.

[0012] Of the three gas flow paths inside the reformer plate, the reforming catalyst reforms the raw fuel in the central flow path, and at the same time absorbs heat from the central part of the unit cells that are in contact with each other vertically. The reformed fuel gas is supplied to each unit cell via gas passages on both sides and a fuel manifold hole.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An internal reforming molten carbonate fuel cell according to an embodiment of the present invention will be described below with reference to the drawings.

Embodiment 1 In FIGS. 1 and 2, a reformer plate 1 is sandwiched between unit cells 2 and has a structure similar to the bipolar plate of the unit cell 2. For this reason, it can function as a part of a battery in combination with the fuel electrode 3, the electrolyte plate 4, and the oxidant electrode 5. The reformer plate 1 and the unit cell 2 are each provided with a raw fuel gas supply internal manifold hole 6, a fuel gas manifold hole 7, an oxidizing gas manifold 8, and their exhaust gas manifolds, which are installed vertically through the stack. These gases are supplied or exhausted from a lower header 11.

[0015] For the raw fuel gas supply internal manifold hole 6 has seen the opening to the reformer plate 1 inside the raw fuel supplied from here, have such is supplied to the unit cell 2.

The reformer plate 1 has a notch 1 inside.
Divided into three gas channels by a partition 16 having 5
The reforming catalyst 12 is provided only at the center of the flow path located at the center. Also the outer edge portion 1a of the reformer plate 1 has opening into the raw fuel gas supply internal manifold holes 6 (you have not shown), wherein the raw fuel is supplied, in the middle of the reforming catalyst 12 After passing through the portion where no reforming catalyst 12 is present, the portion where the reforming catalyst 12 is filled comes into contact with the reforming catalyst 12 and is reformed.
The flow of the reformed fuel gas is reversed from the notch 15 through the gas flow paths on both sides, and is supplied to each unit cell 2 from the fuel gas outlet through the fuel gas manifold hole 7.

In FIG . 2, when viewed as a bipolar plate,
The electrode 3 side is the upper surface, and the oxidizer electrode 5 side is the lower surface.
You. The oxidizing gas is supplied from the oxidizing gas manifold 8.
The exhaust gas supplied to the unit cell 2 and reacted is used as a fuel exhaust gas
Exhaust from the manifold 9 and the oxidant exhaust manifold 10
It is.

FIG . 2 shows an end plate of the reformer plate 1 on the fuel electrode side.
14 shows a state in which the gas leakage is actually removed.
Outer edge 1 by welding or brazing
a. Outer edge portion 1a of reformer plate 1
And the end plate 14 is made of a heat-resistant alloy,
Supports made of the same beam and having sufficient mechanical strength
Height at which 13 is in contact with end plate 14 having a bipolar plate structure
It is installed in. The reformer plate 1 of this embodiment has a size
Is 40 cm square, the thickness is 1.2 cm, and the support portion 13 is 1
These were placed at 5 cm intervals in a cm square.

In view of the above process from the viewpoint of heat balance, the flow path portion where there is no reforming catalyst 12 from the raw fuel gas supply internal manifold hole 6 and the fuel gas after reforming pass through both gas flow paths In the process of reaching the gas manifold hole 7, the cell 2
The exchange of heat with the cell 2 is extremely small, and a large heat absorption occurs near the center where the reforming is performed, so that the vicinity of the center of the unit cell 2 is mainly cooled.

Incidentally, in a fuel cell, generally speaking, the temperature tends to be higher in the central portion than in the peripheral portion. In the case of a large stack, the unit cell 2 depends on the supply direction of the fuel gas and the oxidizing gas, for example, whether it is a direct flow or a parallel flow.
Although the internal temperature rise part changes, the tendency is that the part from the center also tends to become hotter. In particular, in the case of a relatively small-scale stack used for on-site power generation or the like, such a tendency is remarkable because the influence of heat radiation from the side surface of the stack increases. For this reason, in the reformer plate 1 of this embodiment, heat absorption due to the reforming reaction is concentrated near the center, and heat exchange is extremely small in other gas flow paths, so that the temperature rise in the central part of the unit cell 2 is effectively suppressed. This can greatly contribute to uniform temperature of the stack.

This reformer plate 1 is used for a unit cell of 40 cm square.
2 is installed at the center of the stack of 10 cells
The test was performed. The raw fuel gas is desulfurized city gas
(Methane main component) steam / carbon ratio of 3.0
Steam is added at 650 ° C.
Supply to the reformer plate 1 using the supply internal manifold holes 6
Paid. The oxidizing gas contains 70% air and 30% carbon dioxide.
The mixed gas was also supplied with preheating. Also, while driving,
The tack pressure was 4 tons (2.5 kg / cm2). When the temperature distribution of the reformer plate 1 was measured in a state where the stack was operated at an average temperature of 650 ° C., the temperature was 660 ° C. in the high temperature portion and 630 ° C. in the low temperature portion. It was found to contribute.

The unit cell described in following UeMinoru施例, although reformer plates are both rectangular which other shapes, for example, or the like circle. Or it may be of any type in the manifold holes and the shape of the entrance even may be of any shape irrespective of the actual施例, carried on the possible range of the present invention also arranged.

The structure of the reformer plate was
In the example, the notch is only at the end of the partition, but it can be at any position of the partition. Although for the reforming catalyst in the real施例are illustrated those particulate, which those of other shapes, may be for example one honeycomb. In addition to the catalyst, other objects such as a member for holding the catalyst and a member for removing the carbonate vapor may be present.

[0024]

As is apparent from the above description of the embodiment, the internal reforming type molten carbonate fuel cell of the present invention not only enables the simplification of the gas supply-related structure,
The unit cell group in contact with the reformer plate can be uniformly cooled. In addition , the inside of the reformer plate has a notch
The gas is divided into three gas flow paths, and the reforming catalyst is installed only in the flow path located at the center. Therefore, the heat absorption due to the reaction is concentrated near the center, and the temperature at the center of the unit cell The rise can be effectively suppressed, a more uniform cooling effect can be obtained, and the equipment for controlling the temperature of the battery can be reduced and the reliability can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the concept of the configuration of an internal reforming molten carbonate fuel cell according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a cross section of a part of the reformer plate of the embodiment cut out .

DESCRIPTION OF SYMBOLS 1 Reformer plate 2 Unit cell 6 Internal manifold hole for raw fuel gas supply 7 Manifold hole for fuel gas 8 Manifold for oxidant gas 9 Manifold for fuel exhaust gas 10 Manifold for oxidant exhaust gas 12 Reforming catalyst 15 Partition

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Eiichi Yasumoto 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Koji Gamo Inventor 1006 Kazama Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. In-house (56) References JP-A-2-186565 (JP, A) JP-A-61-58174 (JP, A) JP-A-5-89896 (JP, A)

Claims (1)

(57) [Claims] 1. A reformer plate for reforming a stacked unit cell and a raw fuel, a raw fuel gas supply internal manifold hole provided in a state in which the reformer plate is pierced, and a fuel gas, oxidation A manifold hole for a chemical gas, the unit cell supplies and exhausts the gases through respective manifold holes for the fuel gas and the oxidizing gas, and the reformer plate is a bipolar plate of the unit cell. And has a structure that can supply and discharge only the raw fuel gas supply internal manifold hole and the fuel gas manifold hole, and also functions as a bipolar plate, and is obtained by reforming the supplied raw fuel gas. To supply fuel gas to each unit cell
In the internal reforming molten carbonate fuel cell, the reformer
Three gas flows through a notched partition inside the plate
And reforming only at the center of the channel located at the center.
Medium, and an inner manifold for supplying raw fuel gas
The opening of the hold hole is provided, and the reformed fuel gas is cut out.
Flow through the gas flow path on both sides from
Fuel manifolds on both sides of the internal manifold hole for fuel supply
It is equipped with a configuration to supply to each unit cell through the
Internal reforming molten carbonate fuel cell according to symptoms.