Chemistry: electrical current producing apparatus – product – and – Having magnetic field feature
Patent
1997-04-08
1999-01-05
Kalafut, Stephen
Chemistry: electrical current producing apparatus, product, and
Having magnetic field feature
429 20, 429 35, H01M 804
Patent
active
058560343
DESCRIPTION:
BRIEF SUMMARY
This is a National Stage Application of PCT/EP95/01923, filed May 20, 1995.
The present invention relates to a method and a device for operating a fuel cell system, especially a fuel cell system formed by fuel cells arranged in a stack and surrounded by a protective housing, with an anode input to supply combustion gas to the anodes of the fuel cells, an anode output to carry the burnt combustion gas away from the anodes, a cathode input for adding cathode gas to the cathodes of the fuel cells, and a cathode output to carry the used cathode gas away from the cathodes, with the combustion gas being supplied to the anode input through a combustion gas inlet device sealed off from the interior of the protective housing.
In fuel cell systems, a number of generally plate-shaped fuel cells are arranged in the form of a stack, each cell having channels running in a first direction for the combustion gas, and channels for the cathode gas arranged in a second direction, perpendicular to the first direction. The individual fuel cells in the stack are so arranged that an anode input for adding combustion gas to the respective anodes is provided on a first side of the fuel cell stack and an anode output for carrying away the burnt combustion gas from the anodes is provided on the side opposite the first side. A cathode input for supplying cathode gas to the cathodes of the fuel cell stack is provided on a second side of the fuel cell stack, and a cathode output for carrying away the used cathode gas from the cathodes is provided on the side opposite the second side. In high-temperature fuel cells, such as molten carbonate fuel cells (MCFC cells), there are problems with the gas-tight, electrically insulating design of supply lines and exhaust lines for the combustion gas and the cathode gas (manifolds) of the fuel cell stack, which are subjected to high operating temperatures as well as extreme temperature fluctuations during startup and shutdown of the fuel cell system. Gas supply and exhaust lines that are not tight could leak, posing the risk of explosion for example.
In fuel cell systems of the known type, gas distributors are provided as gas inlet devices and gas outlet devices for the combustion gas and the cathode gas to and from the inputs and outputs of the anodes and cathodes, respectively, either integrated into the cell stack (internal manifold) or mounted externally on the cell stack (external manifold). In fuel cell systems with external gas distributors, the latter are conventionally provided as hood-shaped gas inlet and gas outlet devices on the four sides of the fuel cell stack. The system thus formed is provided externally with heat insulation and installed completely within a protective housing. The connections of the gas distributors are guided in the form of pipes with equalizing bellows connected between them through the wall of the protective housing and connected to external units and assemblies. This involves a number of disadvantages. These include: complex guidance for the gas between the fuel cell system and the external assemblies and units, many interfaces and pipe connections, high flow resistances in the pipe connections, and a high cost for sealing and electrical insulation between the cell stack and the four gas hoods under the conditions of high temperatures and temperature changes, corresponding thermal deformations, and high DC current.
The goal of the present invention is to provide a method and a device for operating a fuel cell system of the species recited at the outset, in which the problems related to the sealing of the inputs and outputs of the anodes and cathodes of the fuel cell stack are largely avoided.
This goal is achieved according to the present invention by discharging both the used cathode gas and the burnt combustion gas from the fuel cell stack directly into the interior of a protective housing which surrounds the fuel cell stack. A blower which is arranged inside the housing causes the used cathode gas to mix with the burnt combustion gas and recirculate to the
REFERENCES:
patent: 3664873 (1972-05-01), Buswell et al.
patent: 3718506 (1973-02-01), Fischer et al.
patent: 4738905 (1988-04-01), Collins
patent: 4983471 (1991-01-01), Reichner et al.
patent: 5612149 (1997-03-01), Hartvigsen et al.
Huppmann Gerhard
Kraus Peter
Kalafut Stephen
MTU Mortoren-und Turbinen-Union
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