JPH0750614B2 - Fuel cell - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel cell, and more particularly, to a fuel for heating and raising the temperature of the gas supplied to the cell by utilizing the exhaust heat of the gas exhausted from the cell. The present invention relates to a battery structure and a gas header structure used therein.

[Conventional technology]

The conventional fuel cell is, for example, as described in Nihon Kogyo Shimbun Co., Ltd., Energy, Vol.24, No.4, p.30 (1990) MW class MCFC power generation plant, the anode gas that is the fuel gas is reformed. The gas obtained from the reactor is used, and the cathode gas, which is the oxidant gas, circulates the exhaust gas from the reformer, the air from the compressor and the cathode gas discharged from the fuel cell, and mixes them. (Fig. 7 shows its outline).

[Problems to be Solved by the Invention]

In the case of a molten carbonate fuel cell, the operating temperature is considered to be around 650 ° C. As a method of power generation for the cell, at the start of power generation, after heating the laminated battery to around 650 ° C by the heater around it, the anode and Supply cathode gas.
The temperature inside the battery rises due to the heat generated by the electrochemical reaction and the heat generated by the conduction of electric ions in the battery. Therefore, after a certain period of time from the start of power generation, the surrounding heaters are shut off, and only the battery operates independently.

In this case, the gas temperature supplied to the battery is naturally required to be a high temperature gas of 650 ° C. level.
H ₂ gas is the anode gas, when using a gas from the prior art system diagram of a plant reformer as shown in (Figure 7), the gas temperature is at a relatively high temperature at 700 ° C. or higher However, the mixed gas of CO ₂ and air, which is the cathode gas,
Since the temperature of the compressed air supplied from the compressor is relatively low, even if the temperature rise due to the exhaust gas from the reformer and the circulating gas from the battery is taken into consideration, another heating It was necessary to raise the gas temperature by means.

Therefore, in a conventional power plant, a gas heater is usually provided in the cathode gas supply line to heat the cathode gas to a level of 650 ° C. However, providing a heater in the gas line in this way
Considering the recent increase in the output of fuel cells and the accompanying increase in the amount of gas supply, the auxiliary equipment for heating the gas becomes large, and the power required to drive it also increases. There is a problem that the power generation efficiency as a whole decreases.

In addition, as in the above-mentioned conventional technique, regarding the method of raising the temperature of the supply gas to the fuel cell, in the case where no special consideration is made, when an auxiliary device such as a gas heater is not used,
There is a problem that the temperature of the gas supplied to the fuel cell is lowered and the power generation performance is lowered.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional fuel cell and to allow the temperature of the gas supplied to the fuel cell to be heated and raised without using a special auxiliary device.

Another object of the present invention is to provide a gas header that is specially designed so that the temperature of the gas supplied to the fuel cell can be heated and raised without using any special auxiliary equipment.

Still another object of the present invention is to provide a fuel cell using the above means and having high power generation efficiency.

[Means for Solving the Problems]

The above-mentioned object is a fuel cell in which a unit cell having an electrolyte plate, an anode and a cathode sandwiching the electrolyte plate from both sides, and a separator plate for separating an anode gas which is a fuel gas and a cathode gas which is an oxidant gas are laminated, The fuel gas or oxidant gas supply pipe and the exhaust pipe provided in the battery are constituted by a single pipe body having a double pipe structure, and one of the double pipes is used as an intake pipe and the other is used as an exhaust pipe. It is achieved by

In this case, the purpose of raising the temperature of the cathode gas is to use a dual-pipe supply / exhaust pipe as an oxidant gas supply / exhaust pipe, an inner pipe as a gas supply pipe, and an outer pipe as a gas exhaust pipe. It can be achieved more effectively.

Further, a supply / exhaust pipe having a double pipe structure is provided as a pair so as to be opposed to both side portions of the fuel cell, and gas supplied from one supply / exhaust pipe is exhausted from the other supply / exhaust pipe, respectively. With the structure, by making the gas flow direction of each unit cell the opposite direction for each adjacent unit cell,
A fuel cell having a uniform temperature gradient in a unit cell can be obtained, and the object can be achieved more.

The present invention also provides a gas supply / exhaust header that can be effectively used to achieve the above object.
That is, both the air supply chamber and the exhaust chamber are formed in one side portion in the gas supply / exhaust header, and the air supply pipe to the air supply chamber and the exhaust pipe from the exhaust chamber have a double pipe structure. For one tube with
There is provided a gas supply / exhaust header for use in a fuel cell, which has a structure in which one of the heavy pipes is connected to the air supply pipe and the other is connected to the exhaust pipe.

Further, such a double pipe structure is provided with two air supply chambers and an exhaust chamber at two side portions of the gas supply / exhaust header that face each other, and an air supply pipe for the air supply chamber is provided. 2 with the exhaust pipe from the exhaust chamber
A gas supply having a structure in which one tube having a heavy pipe structure is connected so that the gas supplied from the air supply pipe of the one double pipe is exhausted from the exhaust pipe of the other double pipe. By using the exhaust header, it is possible to obtain a fuel cell having a uniform temperature gradient in the unit cell, and further it is possible to achieve the object.

[Action]

By adopting a double-pipe structure for the gas supply / exhaust pipe of the fuel cell, for example, it becomes possible to use the inner pipe as the supply gas flow path to the cell and the outer pipe as the exhaust gas flow path from the cell, and to exhaust the gas from the cell With the high temperature gas, the gas supplied to the battery can be heated and heated. As a result, it is not necessary to provide an auxiliary device such as a heater in the gas supply line, the power generation efficiency of the entire system can be improved, and the system can be made compact.

Particularly preferably, by directly connecting the supply / exhaust pipe of the double pipe structure to the header portion for gas supply and exhaust provided in the fuel cell, the pipeline is cooled in the middle of the pipe and the gas temperature lowers. And the supply of high temperature gas to the battery can be further improved.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. First
An embodiment of the present invention is shown in FIGS.

As shown in FIG. 1, a gas header 2 for supplying and exhausting gas from the outside to the battery 1 or from the battery 1 to the outside is located at the lower end of the laminated battery 1 in which unit batteries are laminated. In this gas header 2, a supply / exhaust pipe P having a double pipe structure in which a supply pipe for an oxidant gas is configured as an inner pipe 3 and an exhaust pipe is configured as an outer pipe 4, and a supply pipe 5 for fuel gas and an exhaust are provided. A tube 6 is attached.

An electrolyte plate 7 and a separator plate 8 are provided on the gas header 2.
And are alternately stacked with electrodes (not shown) in between,
One laminated battery is configured.

FIG. 2 shows the internal structure of the gas header 2. The inside of the gas header 2 is a chamber for supplying and exhausting fuel gas 10,1
1 and an oxidant gas supply / exhaust chamber 12, 13. The fuel gas supply chamber 10 is connected to an intake pipe 5, and the exhaust chamber 11 is connected to an exhaust pipe 6.

Further, the inner tube 3 as the above-mentioned air supply tube is connected to the chamber 12 for supplying the oxidizing gas, and the inner tube 3 is
It passes through the exhaust chamber 13 located on the opposite side and extends to the outside. On the other hand, in the exhaust chamber 13, the outer pipe 4 as the exhaust pipe described above extends outward in a state of including the air supply inner pipe 3 inside. Therefore, the inner pipe 3 and the outer pipe 4 have a structure which extends from the exhaust chamber in a double pipe structure to form a supply / exhaust pipe P having a double pipe structure (see FIG. 1).

Then, in each of the air supply chambers 10 and 12, manifolds 14 and 15 for supplying gas to the laminated battery are provided, and
The exhaust chambers 11 and 13 are provided with manifolds 16 and 17 for exhausting gas.

The fuel gas G1 supplied from the outside and the oxidant gas G2 flowing through the inner pipe 3 of the supply / exhaust pipe P of the double pipe structure respectively flow into the chambers 10 and 12 in the gas header 2, and from there, each gas. Flow into the supply manifolds 14 and 15 and are distributed to each unit cell. Then, after power generation by an electrochemical reaction in each unit cell, the fuel gas is passed through the discharge manifold 16 as a mixed gas G1 ′ of the residual gas and the generated gas,
After flowing into the exhaust chamber 11, it flows out of the battery through the exhaust pipe 6. On the other hand, the exhaust gas G2 ′ of the oxidant passes through the exhaust manifold 17 and passes through the chamber 13 in the gas header 2.
And then flows out of the battery through the exhaust pipe which is the outer pipe 4 of the supply / exhaust pipe P having the double pipe structure.

The effects of the present invention will be described. Usually, the feed gas is accompanied by an increase in temperature between its inlet and outlet. FIG. 3 shows a change in gas temperature in the battery. The measured battery shape is the same as that in the conventional battery, in which the oxidant gas is flowed into the gas header through one inflow pipe. This is a case where a heater is provided in the middle of the pipe to heat the temperature of the gas so that the inlet gas temperature in the gas header becomes 550 ° C.
As shown in FIG. 3, the gas flowing at 550 ° C. at the inlet part generates heat at the outlet part due to heat generation accompanying power generation in the battery,
The temperature rises around 730 ℃ and about 180 ℃.

The present invention was obtained by paying attention to the rise in the gas temperature. As shown in the embodiment of FIGS. 1 and 2, the oxidant gas pipe is composed of an inner pipe 3 and an outer pipe 4. Since the inner pipe 3 has an inflow pipe and the outer pipe 4 has an outflow pipe, the exhaust gas G2 'is exhausted to heat the inlet gas G2.

In this embodiment, as the piping structure, as described above with reference to FIG. 2, the gas header 2 is directly attached with the supply / exhaust pipe P having a double pipe structure, and the inside of the gas header 2 is used as a gas supply pipe. 3 is penetrated and is connected to the gas supply side chamber 12. The inside of the gas header 2 is in a high temperature atmosphere due to heat dissipation by the high temperature gas, and it becomes possible to flow the oxidant gas G2 into the supply gas chamber 12 without cooling the inner pipe 3 as the gas inflow pipe. .

As described above, according to the present embodiment, the heating temperature of the supply gas to the laminated battery is raised by the exhaust heat of the exhaust gas without using a special auxiliary machine. Not only can the efficiency be improved, but the system can be made compact.

FIG. 4 shows another embodiment according to the present invention. Also in this embodiment, the gas gas header 2 is provided with a side portion where the supply and exhaust chambers 10 and 11 for the fuel gas face each other, and a chamber for the oxidant gas is provided in the other side of the gas header 2. However, the chamber for the oxidizing gas is different from that of the first embodiment.

As shown in FIG. 4, one of the two chambers for the oxidant gas located vertically is
An oxidizing gas supply gas chamber 12A and an exhaust chamber 13B are arranged, and an oxidizing gas supply gas chamber 12B and an exhaust chamber 13A are similarly arranged, and the supply gas chamber 12A is further arranged. , 12B are air supply manifolds 15A, 15B, and exhaust chambers 13B, 13B.
Exhaust manifolds 17B and 17A are formed in A, respectively.

Furthermore, oxidant gas air supply pipes are connected to the respective gas supply gas chambers 12A and 12B as inner pipes 3A and 3B,
Exhaust pipes are connected to the exhaust gas chambers 13B and 13A as outer pipes 4A and 4B so as to cover the inner pipes 3A and 3B as in the case of the embodiment shown in FIG. The pipe and the outer pipe form supply / exhaust pipes P and P'having a double pipe structure.

Then, the oxidant gas G2 that has passed through the inner tubes 3A and 3B in the double tube
Flows into the gas supply gas chambers 13A and 13B on both sides, respectively, and is supplied to each unit cell through the manifolds 15A and 15B. Exhaust gas G2 'from each unit battery returns to the exhaust gas chambers 13A, 13B through the manifolds 17A, 17B, and flows out to the outside through the outer pipes 4A, 4B of the double pipe structure supply / exhaust pipe P.

FIG. 5 shows the shape of the cathode surface of the separator 8 in the laminated battery according to the present embodiment. The laminated battery has a cathode B supplied with the oxidizing gas from the supply manifold 15B.
A unit cell having a surface (Fig. 5 (b)) and a unit battery having a surface of a cathode A (Fig. 5 (a)) supplied with the oxidizing gas from the supply manifold 15A are alternately laminated. Is formed by. As shown in the figure, the oxidant gas G2 flowing from the manifolds 15B and 15A of the separator 8 is not shown in the figure, but a gas flow path formed by separator ribs provided as necessary is shown in FIG. ),
Flow as indicated by the arrow in (a), and discharge manifold
After flowing into 17B and 17A, it is then discharged to the outside through the outer pipes 4B and 4A of the supply / exhaust pipe P of the double pipe structure provided in the gas header 2 shown in FIG.

In this embodiment, by adopting such a structure, in addition to the effect of raising the temperature of the supply gas by the exhaust heat of the exhaust gas described in the previous embodiment, the temperature distribution of the entire laminated battery is made uniform. There is an effect of doing.

That is, to explain the uniformization of the temperature distribution, as shown in FIG. 3, when the gas flow direction is from one direction, there is a large temperature difference between the gas inlet portion and the gas outlet portion. This temperature difference can be said for the whole laminated battery,
The temperature distribution in the battery becomes uneven. If the temperature distribution in the battery becomes non-uniform, various problems such as performance deterioration due to non-uniform reaction distribution, increase in thermal stress, and increase in material corrosion factors will occur when considering the performance, life and reliability of the battery. Occurs. Therefore, the battery structure of this embodiment is effective as a means for making this temperature distribution uniform.

FIG. 6 shows the temperature in the gas flow direction on the cathode surface and the temperature change of the laminated battery in this example. A broken line a in the figure shows a temperature change on the cathode A surface in FIG. 4 (a), and a broken line b shows a temperature change on the cathode B surface in FIG. 4 (b). In each unit cell, a large temperature difference occurs between the gas inlet and the gas outlet as described above, and the temperature distribution of the laminated battery is also non-uniform.

Therefore, as shown in FIGS. 4 (a) and 4 (b), the gas flow direction is made to alternately flow in the opposite direction for each unit cell of the laminated battery. By doing so, as shown in FIG. 6, the cathode A surface and the adjacent cathode B surface have a temperature change as shown by the broken line b, and when both surfaces are laminated, a high temperature region and a low temperature region are generated. Because they overlap
Due to mutual heat transfer, the temperature of the laminated cell as a whole changes uniformly between the inlet and the outlet as shown by the solid line in the figure, and a fuel cell with a uniform temperature distribution can be obtained.

As described above, according to this example, in addition to the effects of the previous example, it becomes possible to make the temperature distribution of the entire laminated battery uniform, and the fuel with further excellent performance, life, reliability, etc. You can get a battery.

In the above description, the pipe for supplying and exhausting the oxidant gas has been described as having a double pipe structure. However, the technology for making the pipe structure for supplying and exhausting the double pipe structure It will be apparent that the idea can be applied to piping for fuel gas supply and exhaust as necessary. Further, it may be used for the structure of the supply and exhaust pipes for both the fuel gas and the oxidant gas.

〔The invention's effect〕

According to the present invention, the heating temperature of the supply gas to the laminated battery is raised,
Since it can be performed by exhaust heat of exhaust gas, the efficiency of the power generation system for the entire battery is improved, and the system can be made compact.

Further, the gas flow direction of each unit cell of the laminated battery can be made to be the opposite direction, the temperature distribution of the entire laminated battery can be made uniform, and a fuel cell excellent in performance, life and reliability can be obtained. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a battery laminated structure of one embodiment of the present invention, FIG. 2 is a diagram showing a structure in a gas gas header, FIG. 3 is a diagram showing a gas temperature change in a battery, and FIG. 4 is a book. The figure which shows the structure in the gas gas header in the other Example of invention, 5th
FIG. 6 is a diagram for explaining the gas flow direction in the separator, FIG. 6 is a diagram showing a gas temperature in the cell and a temperature change of the laminated cell, and FIG. 7 is a system configuration of a power generation blunt using a fuel cell in a conventional example. It is a figure. 1 ... laminated battery, 2 ... gas header, 3 ... inner tube,
4 ... Outer pipe, P ... Supply / exhaust pipe of double pipe structure, 5 ... Fuel gas supply pipe, 6 ... Fuel gas exhaust pipe, 7 ... Electrolyte plate, 8 ... Separator plate, 10 ... … Fuel gas supply champer, 11 …… Fuel gas exhaust champer, 12 ……
Oxidant gas supply chamfer, 13 …… Oxidant gas exhaust champer, 14, 15 …… Air supply manifold, 16, 17
...... Exhaust manifold, G1 …… Fuel gas, G1 ′ …… Fuel gas exhaust gas, G2 …… Oxidizing gas, G2 ′ …… Oxidizing gas exhaust gas

Claims (6)

[Claims] 1. A fuel cell in which unit cells having an electrolyte plate, an anode and a cathode sandwiching the electrolyte plate from both sides, and a separator plate for separating an anode gas as a fuel gas and a cathode gas as an oxidant gas are laminated, The air supply pipe and the exhaust pipe for the fuel gas and / or the oxidant gas provided in the fuel cell are configured by a single pipe body having a double pipe structure, one of the double pipes is an air supply pipe, and the other is an exhaust pipe. A fuel cell, which is characterized by being used as a fuel cell. 2. The fuel cell according to claim 1, wherein a supply / exhaust pipe having a double pipe structure has a gas supply pipe as an inner pipe and a gas exhaust pipe as an outer pipe. 3. The fuel cell according to claim 1 or 2, wherein the supply / exhaust pipe having a double-pipe structure is an oxidant gas supply / exhaust pipe. 4. The fuel cell according to claim 1, wherein the supply / exhaust pipes having a double pipe structure are provided as a pair so as to face each other, and the gas supplied from one of the supply / exhaust pipes is supplied to the other. The fuel cell is configured to be exhausted from the air supply / exhaust pipe, and the gas flow direction of each unit cell is set to the opposite direction for each adjacent unit cell. 5. An air supply chamber and an exhaust chamber are formed at one side portion in a gas supply / exhaust header, and an air supply pipe to the air supply chamber and an exhaust pipe from the exhaust chamber are provided in two sides. For one tube with a heavy tube structure,
The gas supply / exhaust header for use in a fuel cell according to claim 1, wherein one of the heavy pipes is connected to the air supply pipe and the other is connected to the exhaust pipe. 6. A gas supply / exhaust header is provided with two air supply chambers and an exhaust chamber, respectively, at two side portions that oppose each other, and an air supply pipe to the air supply chamber and exhaust from the exhaust chamber. The pipe is connected to one pipe body having a double pipe structure so that the gas supplied from the air supply pipe of the one double pipe is exhausted from the exhaust pipe of the other double pipe. The gas supply / exhaust header used in the fuel cell according to claim 5, wherein the header has a structure.