JPH0722044A - Fuel cell power generating system - Google Patents

Abstract

PURPOSE:To ensure safety even with gas leaks so as to restrain corrosion by providing a purge line, and supplying combustion exhaust that contains oxygen controlled to a predetermined concentration into a containment vessel. CONSTITUTION:A fuel cell 20 is contained in a containment vessel 22 and generates power from anode gas 2 containing hydrogen and cathode gas 3 containing oxygen. A node exhaust 4 emitted from the fuel cell 20 is burned with part of cathode exhaust 7, and a reformer 10 reforms combustion gas into anode gas by the heat of the burning. An exhaust circulation line 30 supplies the combustion exhaust from the reformer 10 to the cathode gas that enters the fuel cell 20, and a power recovery system 40 compresses air with the rest of the cathode gas from the fuel cell 20 and supplies the air to the line 30. Further, a controller 35 controls oxygen contained in the combustion exhaust 5 on line 30 to a predetermined concentration and a purge line 36 supplies the combustion exhaust with the controlled oxygen concentration to the vessel 22. Thereby safety is ensured even with leakage of the anode gas, and corrosion of the cell can be restrained while the operating cost of the purge gas is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power generator, and more particularly to a fuel cell power generator using a molten carbonate fuel cell.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have characteristics that conventional power generators do not have, such as high efficiency and little impact on the environment, and they are attracting attention as a power generation system following hydropower, thermal power, and nuclear power. Is currently being researched and developed all over the world. In particular, in a power generation facility using a molten carbonate fuel cell using natural gas as a fuel, a reformer 10 for reforming a fuel gas 1 such as natural gas into an anode gas 2 containing hydrogen as shown in FIG. A fuel cell 20 for generating power from an anode gas 2 and a cathode gas 3 containing oxygen is generally provided, and the anode gas produced by the reformer is supplied to the fuel cell, and most of it (in the fuel cell) (For example, 80%), the combustion chamber C of the reformer 10 is used as the anode exhaust gas 4.
supplied to the o. The fuel gas 1 is preheated by the fuel preheater 11 and enters the reforming chamber Re of the reformer. In the reformer, combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas
Are burned in the combustion chamber and the high temperature combustion gas heats the reforming chamber Re to reform the fuel flowing inside. The combustion exhaust gas 5 that has exited the reforming chamber is subjected to heat recovery by the air preheater 32, and the condenser 33
The water 6 is removed by the steam separator 34 and the air 6 pressurized by the turbine compressor (power recovery device 40) is mixed, and this mixed gas is heated by the air preheater 32 and joins the cathode gas 3. . As a result, 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 supplies carbon dioxide required for the cathode reaction of the fuel cell to the cathode side C. Cathode gas 3
Is partially reacted in the fuel cell to form cathode exhaust gas 7, part of which is recirculated to the cathode inlet side, and part of which is supplied to the combustion chamber Co of the reformer 10 to form the anode exhaust gas 4
Is burned, and the rest is supplied to the power recovery device 40 to recover the pressure and is discharged to the outside of the system.

[0003]

In the above-mentioned fuel cell power generator, the fuel cell 20 is normally stored in the storage container 22. In this case, an inert gas 8 (for example, nitrogen gas) was supplied as a purge gas into the storage container as a safety measure when the anode gas leaks. However, it has been found that when an inert gas containing no oxygen is used as a purge gas, a metal component (eg, a separator) constituting the cell is severely corroded by a local reaction in the fuel cell. Further, there is a problem in that operating cost is required when the inert gas is used as the purge gas.

The present invention was created to solve such problems. That is, an object of the present invention is to provide a fuel cell power generator that is safe even if the anode gas leaks, can suppress the corrosion of the cell, and does not incur the operating cost of the purge gas.

[0005]

According to the present invention, a fuel cell which is stored in a storage container and generates electricity from an anode gas containing hydrogen and a cathode gas containing oxygen, and an anode exhaust gas discharged from the fuel cell to a cathode A reformer that burns part of the exhaust gas and uses the heat to reform the fuel gas into the anode gas, an exhaust gas circulation line that supplies the combustion exhaust gas that exits the reformer to the cathode gas that enters the fuel cell, and the fuel cell In a fuel cell power generator comprising: a power recovery device that compresses air with the remaining cathode exhaust gas and supplies the compressed air to the exhaust gas circulation line, the exhaust gas circulation line controls oxygen contained in the combustion exhaust gas to a predetermined concentration. And a purge line for supplying the combustion exhaust gas with controlled oxygen concentration into the storage container.

According to a preferred embodiment of the present invention, the concentration control device comprises an oxygen sensor for detecting the oxygen concentration contained in the combustion exhaust gas, and an exhaust gas circulation line so that the concentration detected by the oxygen sensor becomes a predetermined concentration. And a flow rate control device for controlling the flow rate of the blower provided. Preferably, the predetermined concentration is about 3%.

[0007]

According to the above-mentioned structure of the present invention, the exhaust gas circulation line is provided with the concentration control device, and by this concentration control device, the oxygen contained in the combustion exhaust gas is controlled to a predetermined concentration and the oxygen concentration is controlled. The combustion exhaust gas is supplied into the containment vessel through the purge line. Therefore, it is safe even if the anode gas leaks in the storage container due to the purge gas containing a predetermined concentration of oxygen, and the corrosion of the battery can be suppressed. When the predetermined concentration is about 3%, both safety and suppression of battery corrosion can be satisfied.

If the flow rate control device controls the flow rate of the blower provided in the exhaust gas circulation line so that the concentration detected by the oxygen sensor becomes a predetermined concentration, the purge gas can be self-supplied and the operating cost of the purge gas can be reduced. Can be significantly reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. The same parts as those in FIG. 2 are designated by the same reference numerals and used. FIG. 1 is an overall configuration diagram of a fuel cell power generator according to the present invention. In this figure, a fuel cell power generator according to the present invention includes a reformer 10 for reforming a fuel gas 1 into an anode gas 2 containing hydrogen, and a fuel cell 20 for generating power from an anode gas 2 and a cathode gas 3 containing oxygen.
And an air preheater 32 for recovering heat from the combustion exhaust gas 5 exiting the reformer 10. The reformer 10 is a fuel cell 2
The anode gas (ie, the anode exhaust gas 4) having a value of 0 is burned by a part of the cathode gas (ie, the cathode exhaust gas 7), which has exited the fuel cell 20, and the heat thereof reforms the fuel gas 1 into the anode gas 2. ing. Fuel cell 2
0 is stored in the storage container 22.

The fuel cell power generator according to the present invention further comprises:
The exhaust gas circulation line 30 that supplies the combustion exhaust gas 5 that has exited the reformer 10 to the cathode gas 3 that enters the fuel cell 20, and the remaining portion of the cathode exhaust gas 7 that exits the fuel cell 20 compresses air to the exhaust gas circulation line 30. And a power recovery device 40 for supplying the power. The exhaust gas circulation line 30 is connected to the combustion exhaust gas 5
Concentration control device 3 for controlling the oxygen contained in water to a predetermined concentration
5 and the combustion exhaust gas whose oxygen concentration is controlled
And a purge line 36 for supplying the inside. The concentration control device 35 controls the flow rate of an oxygen sensor 37 for detecting the oxygen concentration contained in the combustion exhaust gas and a flow rate of a circulation blower 38 provided in the exhaust gas circulation line so that the concentration detected by the oxygen sensor becomes a predetermined concentration. And a control device 39. The predetermined concentration may be about 3%.

The above-mentioned concentration controller 35 operates as follows. When the oxygen concentration contained in the combustion exhaust gas 5 is higher than a predetermined concentration, the oxygen sensor 37 detects this concentration, and the flow control device 39 reduces the flow rate of the circulation blower 38.
As a result, the remainder of the cathode exhaust gas 7 (power recovery device 4
(Leading to 0) is reduced, the supply of air 6 from the power recovery device 40 is reduced, and the concentration of oxygen contained in the combustion exhaust gas 5 is reduced. On the contrary, when the oxygen concentration contained in the combustion exhaust gas 5 is lower than the predetermined concentration, the oxygen sensor 37 detects this concentration,
The flow controller 39 increases the flow rate of the circulation blower 38. As a result, the cathode exhaust gas 7 increases, the supply of the air 6 from the power recovery device 40 increases, and the combustion exhaust gas 5 increases.
The oxygen concentration contained in is increased.

[0012]

With the above-described structure, the combustion exhaust gas with controlled oxygen concentration is supplied to the storage container 22 by the purge line 36.
Is supplied to the anode gas 2 in the storage container 22 by a purge gas containing oxygen of a predetermined concentration (preferably about 3%).
Is safe even if leaked, and the corrosion of the battery can be suppressed. Further, since the flow rate control device 39 controls the flow rate of the circulation blower provided in the exhaust gas circulation line 30 so that the concentration detected by the oxygen sensor 37 becomes the predetermined concentration, the purge gas can be self-supplied and the purge gas can be operated. The cost can be reduced significantly.

Therefore, the present invention has excellent effects such that it is safe even if the anode gas leaks, the corrosion of the battery can be suppressed, and the operating cost of the purge gas is low.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fuel cell power generator according to the present invention.

FIG. 2 is an overall configuration diagram of a conventional fuel cell power generator.

[Explanation 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 8 Purge Gas 10 Reformer 11 Fuel Preheater 20 Fuel Cell 22 Containment Vessel 30 Exhaust Gas Circulation Line 32 Air Preheater 33 Condenser 34 Gas Water Separator 35 Concentration control device 36 Purge line 37 Oxygen sensor 38 Circulation blower 39 Flow rate control device 40 Power recovery device Re Reforming chamber Co Combustion chamber A Anode side C Cathode side

Claims (3)

[Claims] 1. A fuel cell, which is stored in a storage container and generates electricity from an anode gas containing hydrogen and a cathode gas containing oxygen, and an anode exhaust gas that has exited the fuel cell is burned in a part of the cathode exhaust gas to generate heat. A reformer that reforms fuel gas into anode gas, an exhaust gas circulation line that supplies the combustion exhaust gas that exits the reformer to the cathode gas that enters the fuel cell, and the air that is compressed by the remainder of the cathode exhaust gas that exits the fuel cell. In the fuel cell power generation device including a power recovery device that supplies the exhaust gas circulation line to the exhaust gas circulation line, the exhaust gas circulation line is a concentration control device that controls oxygen contained in the combustion exhaust gas to a predetermined concentration, and the oxygen concentration is controlled. A purge line for supplying the generated combustion exhaust gas into the storage container. 2. The concentration control device controls an oxygen sensor for detecting the oxygen concentration contained in the combustion exhaust gas, and a flow rate of a blower provided in the exhaust gas circulation line so that the concentration detected by the oxygen sensor becomes a predetermined concentration. The fuel cell power generator according to claim 1, further comprising: 3. The fuel cell power generator according to claim 1, wherein the predetermined concentration is about 3%.