Fuel cell system with partial recycling of anode exhaust
First Claim
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1. A method of operating a fuel cell system, comprising:
- providing a fuel inlet stream into a fuel cell stack;
operating the fuel cell stack to generate electricity, an air exhaust stream and a fuel exhaust stream, the fuel exhaust stream having a temperature above 200 C and a first composition immediately after leaving the fuel cell stack;
heating the fuel inlet stream with the entire fuel exhaust stream in a fuel heat exchanger;
heating a fuel cell stack air inlet stream with an output of the fuel heat exchanger in an air preheater heat exchanger;
splitting the fuel exhaust stream into a first split fuel exhaust stream and a second split fuel exhaust stream such that the first and second split fuel exhaust streams have the same first composition;
lowering a temperature of at least the entire of the first or second split fuel exhaust streams to 200 C or less;
recycling the first split fuel exhaust stream into the fuel inlet stream; and
burning the second fuel exhaust stream with the air exhaust stream, wherein heating the fuel inlet stream is performed prior to burning the second fuel exhaust stream;
wherein neither the fuel exhaust stream, the first split fuel exhaust stream nor the second split fuel exhaust stream is passed through a water gas shift reactor.
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Abstract
A method of operating a fuel cell system includes providing a fuel inlet stream into a fuel cell stack, operating the fuel cell stack to generate electricity and a hydrogen containing fuel exhaust stream having a temperature above 200 C, lowering a temperature of the fuel exhaust stream to 200 C or less, separating the fuel exhaust stream into a first separated fuel exhaust stream and a second separated fuel exhaust stream, and recycling the first separated fuel exhaust stream into the fuel inlet stream.
78 Citations
12 Claims
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1. A method of operating a fuel cell system, comprising:
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providing a fuel inlet stream into a fuel cell stack; operating the fuel cell stack to generate electricity, an air exhaust stream and a fuel exhaust stream, the fuel exhaust stream having a temperature above 200 C and a first composition immediately after leaving the fuel cell stack; heating the fuel inlet stream with the entire fuel exhaust stream in a fuel heat exchanger; heating a fuel cell stack air inlet stream with an output of the fuel heat exchanger in an air preheater heat exchanger; splitting the fuel exhaust stream into a first split fuel exhaust stream and a second split fuel exhaust stream such that the first and second split fuel exhaust streams have the same first composition; lowering a temperature of at least the entire of the first or second split fuel exhaust streams to 200 C or less; recycling the first split fuel exhaust stream into the fuel inlet stream; and burning the second fuel exhaust stream with the air exhaust stream, wherein heating the fuel inlet stream is performed prior to burning the second fuel exhaust stream; wherein neither the fuel exhaust stream, the first split fuel exhaust stream nor the second split fuel exhaust stream is passed through a water gas shift reactor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification