Operation of fuel cell systems with reduced carbon formation and anode leading edge damage
First Claim
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1. A method of operating a fuel cell system, comprising:
- introducing a fuel mixture comprising molecular hydrogen, a fuel comprising carbon and hydrogen, and steam at a fuel inlet of a fuel cell of the fuel cell system, said fuel mixture comprising an output of an external reformer that reforms a hydrocarbon fuel to form molecular hydrogen, and the external reformer is coupled to the fuel inlet of the fuel cell of the fuel cell system; and
operating the fuel cell system to generate electricity,wherein a ratio of molecular hydrogen not contained in fuel to carbon contained in the fuel (H2;
Cfuel) in said fuel mixture introduced at the fuel inlet of the fuel cell is within a range of 0.25;
1 to 3;
1, inclusive; and
a ratio of steam to carbon (S;
C) in said fuel mixture introduced at the fuel inlet of the fuel cell is less than 2;
1.
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Abstract
A method of operating a fuel cell system includes introducing a fuel mixture comprising hydrogen, fuel, and steam at a fuel inlet of the fuel cell system, and operating the fuel cell system to generate electricity. A ratio of hydrogen to carbon from fuel (H2:Cfuel) in the fuel mixture is within a range of 0.25:1 to 3:1, inclusive; and a ratio of steam to carbon (S:C) in the fuel mixture is less than 2:1.
81 Citations
22 Claims
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1. A method of operating a fuel cell system, comprising:
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introducing a fuel mixture comprising molecular hydrogen, a fuel comprising carbon and hydrogen, and steam at a fuel inlet of a fuel cell of the fuel cell system, said fuel mixture comprising an output of an external reformer that reforms a hydrocarbon fuel to form molecular hydrogen, and the external reformer is coupled to the fuel inlet of the fuel cell of the fuel cell system; and operating the fuel cell system to generate electricity, wherein a ratio of molecular hydrogen not contained in fuel to carbon contained in the fuel (H2;
Cfuel) in said fuel mixture introduced at the fuel inlet of the fuel cell is within a range of 0.25;
1 to 3;
1, inclusive; and
a ratio of steam to carbon (S;
C) in said fuel mixture introduced at the fuel inlet of the fuel cell is less than 2;
1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of operating a fuel cell system, comprising:
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partially reforming a hydrocarbon fuel in an external reformer that is coupled to a fuel inlet of a fuel cell of the fuel cell system; introducing a fuel mixture comprising the partially reformed hydrocarbon fuel from the external reformer and recycled anode exhaust gas and including steam at the fuel inlet of the fuel cell of the fuel cell system, wherein a portion of the hydrocarbon fuel reformed in the external reformer prior to introduction at the fuel inlet is 5% to 15%; and operating the fuel cell system to generate electricity; wherein the steam to carbon ratio (S;
C) in said fuel mixture introduced at the fuel inlet of the fuel cell is 1;
1 or greater and less than 2;
1. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A solid oxide fuel cell stack, comprising:
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a plurality of electrolyte-supported solid oxide fuel cells and a plurality of interconnects, each of the plurality of fuel cells comprising; a solid oxide electrolyte having a first surface and a second surface and a fuel riser inlet opening extending through the solid oxide electrolyte; an anode electrode on the first surface of the electrolyte and adapted for internal fuel reformation; and a cathode electrode on the second surface of the electrolyte, wherein the cathode electrode includes an outer edge that includes a concave-shaped offset region adjacent to at least a first side of the fuel inlet riser opening, and the concave-shaped offset region is offset from the fuel inlet riser opening by a first distance sufficient to accommodate a seal that surrounds the fuel inlet riser opening on the second surface of the electrolyte but not on the first surface of the electrolyte; wherein the anode electrode and the cathode electrode are symmetrical in a region where fuel enters the fuel cell such that an outer edge of the anode electrode is exactly or substantially aligned with the outer edge of the cathode electrode on an opposite side of the electrolyte in the same fuel cell in the region where fuel enters the fuel cell, and the outer edge of the anode electrode includes a concave-shaped offset region adjacent to at least the first side of the fuel inlet riser opening, and the concave-shaped offset region of the outer edge of the anode electrode is offset from the fuel inlet riser opening by the first distance and wherein the solid oxide fuel cell stack is internally manifolded for fuel. - View Dependent Claims (19, 20, 21, 22)
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Specification