JP2882019B2 - Fuel cell - Google Patents

Description

The present invention relates to a fuel cell.

[Prior Art] Hereinafter, a conventional fuel cell will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a fuel cell main body, which is composed of a stack 2 and a stack container 3 for housing the stack 2.

The stack 2 sandwiches both sides (upper and lower surfaces in FIG. 2) of an electrolyte 4 made of a molten carbonate between an anode 5 (negative electrode) and a cathode 6 (positive electrode) made of a porous material, and an anode gas on the antielectrolyte 4 side of the anode 5. A passage 7 is formed, and a cathode gas passage 8 is formed on the side of the cathode 6 opposite to the anti-electrolyte 4.

Reference numeral 9 denotes an anode gas supply pipe for supplying an anode gas 10 (fuel gas) containing hydrogen such as coal gas, natural gas, methanol, or carbon monoxide to the anode gas passage 7 (fuel gas), and reference numeral 11 discharges the anode gas 10 from the anode gas passage 7. This is an anode gas discharge pipe.

Reference numeral 12 denotes a cathode gas supply pipe for supplying a cathode gas 14 (an oxidizing gas obtained by adding carbon dioxide to a gas such as air containing oxygen) compressed by a compressor 13 to the cathode gas passage 8, and reference numeral 15 denotes a discharge from the cathode gas passage 8. A turbine 16 for driving the compressor 13
And a cathode gas exhaust pipe leading to the chimney 17 through the stack.

Numeral 18 is provided on the inlet side of the cathode 16 of the cathode gas discharge pipe 15, and the fuel 19 is burned by using a part 20 of the cathode gas 14 compressed by the compressor 13, so that the driving power of the turbine 16 is secured only when necessary. Auxiliary combustor for

Reference numeral 21 denotes a nitrogen gas supply pipe for supplying the nitrogen gas in the nitrogen gas tank 22 to the stack container 3, and reference numeral 23 denotes a nitrogen gas discharge pipe for discharging the nitrogen gas in the stack container 3 to the cathode gas discharge pipe 15.

The pressure inside the stack container 3 and the inside of the anode gas passage 7 and the cathode gas passage 8 of the stack 2 is adjusted by a pressure adjusting device (not shown).

In the case of power generation, anode gas 10 (fuel gas containing hydrogen and carbon monoxide) is supplied to the anode gas supply pipe 9, and at the same time, cathode gas 14 (oxygen An oxidizing gas obtained by adding carbon dioxide to a gas such as air containing the oxidizing gas is supplied.

Then, the cathode gas 14 enters the cathode gas passage 8 of the stack 2 and receives electrons from the cathode 6 (positive electrode), whereby carbon dioxide and oxygen in the cathode gas 14 react with each other to generate carbonate ions. The cathode gas 14 for the reaction is supplied from the cathode gas passage 8 to the cathode gas exhaust pipe 15.
After being driven into the turbine 16 and driving the compressor 13 on the way, it is discharged from the chimney 17.

The carbonate ions generated on the side of the cathode 6 move the electrolyte 4 toward the anode 5 (negative electrode), and the hydrogen and / or hydrogen in the anode gas 10 passed from the anode gas supply pipe 9 to the anode gas passage 7 at the anode 5. Reaction with carbon oxide produces water, carbon dioxide and electrons. Electricity is generated in this manner, and water and carbon dioxide generated at the same time are discharged from the anode gas passage 7 to the anode gas discharge pipe 11.

Then, by supplying nitrogen gas from the nitrogen gas tank 22 to the stack container 3 through the nitrogen gas supply pipe 21,
The inside of the stack container 3 is purged with nitrogen gas, and excess nitrogen gas in the stack container 3 is guided to the cathode gas discharge pipe 15 via the nitrogen gas discharge pipe 23 and discharged from the chimney 17.

[Problems to be Solved by the Invention] However, the conventional fuel cell has the following problems.

That is, the nitrogen gas in the nitrogen gas tank 22 is introduced into the stack container 3 in order to purge the inside of the stack container 3 with the nitrogen gas. However, in this case, equipment such as the nitrogen gas tank 22 is required. There is a problem that power generation costs are high because expensive nitrogen gas is used.

The present invention has been made in view of the above circumstances, and has as its object to provide a fuel cell capable of purging the inside of a stack container without using nitrogen gas.

Means for Solving the Problems According to the present invention, an electrolyte is sandwiched between an anode and a cathode, and an anode gas composed of a fuel can be supplied to the anode, and a cathode gas composed of an oxidant can be supplied to the cathode to constitute a stack. In a fuel cell containing the stack in a stack container, a purge gas supply pipe connecting a cathode gas discharge pipe connected to the cathode outlet side to the stack container is provided, and a steam ejector is provided in the middle of the purge gas supply pipe. The present invention relates to a characteristic fuel cell.

[Operation] According to the present invention, a part of the cathode gas discharged to the cathode gas discharge pipe enters the purge gas supply pipe, and is blown into the stack container by the steam force by the steam ejector to purge the stack container.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

 FIG. 1 shows an embodiment of the present invention.

In the figure, the same components as those shown in FIG. 2 are included in the basic configuration of the fuel cell and details of each component, and therefore, the same components are denoted by the same reference numerals. Therefore, the description will be omitted, and only the configuration specific to the present invention will be described below.

A water supply system is provided on the outlet side of the turbine 16 of the cathode gas exhaust pipe 15.
Boiler 26 for exchanging heat with water 25 flowing through 24
Is arranged.

A purge gas supply pipe 27 is connected between the outlet side of the boiler 26 of the cathode gas discharge pipe 15 and the stack container 3, and a steam ejector 28 is provided in the middle of the purge gas supply pipe 27 to provide a water supply system.
Branch pipe 29 from 24 boiler 26 outlet to steam ejector 28
Connect.

In the figure, reference numeral 30 denotes the stack container 3 and the cathode gas discharge pipe 15.
A purge gas discharge pipe 31 communicating with the inlet of the chimney 17 is a water supply pump provided on the inlet side of the boiler 26 of the water supply system 24.

 Next, the operation will be described.

Regarding the process of generating electricity in the fuel cell body 1,
The description is omitted because it is similar to that of FIG.

Cathode gas 14 (exhaust gas, consisting mainly of nitrogen, oxygen and carbon dioxide) flowing through a cathode gas discharge pipe 15 and passing through a turbine 16 then enters a boiler 26 and flows into a water supply system 24 between water 25. Heat exchange is performed to heat the water 25 and lower the temperature of the water 25 itself.

Most of the cathode gas 14 thus cooled is discharged from the chimney 17 and partly flows to the purge gas supply pipe 27 side.

Then, the cathode gas flowing to the purge gas supply pipe 27 side
When the steam reaches the steam ejector 28, a part of the steam generated by heating the water 25 in the boiler 26 is supplied to the steam ejector 28 through the branch pipe 29. Is blown into the stack container 3 to purge the stack container 3.

At this time, since the cathode gas 14 is blown into the stack container 3 by a sufficient amount of vapor, the oxygen in the cathode gas 14 is diluted below the explosion limit, and therefore, the stack container 3 is safely purged. .

Excess cathode gas 14 that has purged the stack container 3 is led from the purge gas discharge pipe 30 to the cathode gas discharge pipe 15 and discharged from the chimney 17.

It should be noted that the present invention is not limited only to the above-described embodiment, and that the supply source of steam to the steam ejector 28 is arbitrary, and various other modifications may be made without departing from the gist of the present invention. Obviously you can get it.

[Effects of the Invention] As described above, according to the fuel cell of the present invention, since the inside of the stack container is purged using the discharged cathode gas, a nitrogen gas tank or the like can be made unnecessary, and
An excellent effect that power generation costs can be reduced can be achieved.

[Brief description of the drawings]

FIG. 1 is an overall system diagram of one embodiment of the present invention, and FIG. 2 is an overall system diagram of a conventional example. In the figure, 2 is a stack, 3 is a stack container, 4 is an electrolyte, 5
Denotes an anode, 6 denotes a cathode, 10 denotes an anode gas, 14 denotes a cathode gas, 15 denotes a cathode gas discharge pipe, 27 denotes a purge gas supply pipe, and 28 denotes a steam ejector.

Claims (1)

(57) [Claims] An electrolyte is sandwiched between an anode and a cathode to form a stack in which an anode gas composed of fuel can be supplied to the anode and a cathode gas composed of an oxidant can be supplied to the cathode, and the stack is housed in a stack container. A fuel cell, comprising: a purge gas supply pipe connecting a cathode gas discharge pipe connected to a cathode outlet side to a stack container; and a steam ejector provided in the middle of the purge gas supply pipe.