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Title:
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Solid oxide fuel cell in combination with a gas turbine [ECN-I--95-020]
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Author(s):
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Published by:
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Publication date:
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ECN
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1995
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ECN report number:
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Document type:
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ECN-I--95-020
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Other
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Number of pages:
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Full text:
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102
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Download PDF
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Abstract:
The results of an assessment study on the 5 MWe title system aredescribed. The goal of the study is to analyze different configurations of
the combination, as described in literature, with special attention for the
integration of these two components and the efficiencies that can be
achieved. Natural gas is one of the most attractive fuels for fuel cells. The
fuel cell system is based on the planar concept of SOFC with a co-flow
configuration. Several parameter variations and system options are performed
for each configuration in order to have an indication of the effect of these
parameters and options on the system performance. Based on the results of
these case studies seven 'optimal' options are developed. Finally, an exergy
analysis of these options is performed to indicate the exergy losses of the
individual components and of the complete system. The following seven options
are considered: (1) SOFC combined with a gas turbine used as bottoming cycle
and a cathode recycle; (2) An option similar to option 1 with both anode and
cathode recycles; (3) An option similar to option 1 but operating at
atmospheric pressure; (4) An option similar to option 2 which is operating at
atmospheric pressure; (5) SOFC combined with a gas turbine in which the fuel
is fed parallel to both components. A cathode recycle is applied in this
option; (6) An option similar to option 5 with both anode and cathode
recycles; (7) SOFC combined with the commercial version of the Heron gas
turbine. The exergy analysis indicates that the highest exergy losses occur
respectively in the combustor, fuel cell, steam generation unit, the power
turbine and the air compressor. Overall exergy losses decrease when an anode
recycle is applied in different configurations. The lowest exergy loss is
obtained with the second option of the bottoming configuration. The following
aspects will help to minimize the exergy losses and increase the overall
exergetic efficiencies: applying an anode recycle; increasing the isentropic
efficiency of compressors and turbines; avoiding high temperature differences
in heat exchangers; avoiding direct combustion of fuel. 16 figs., 40 tabs., 5
appendices, 22 refs.
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