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Title Integrating a SOFC with a steam cycle
Author Scappin, Fabio (Department of Mechanical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Supervisor Rokni, Masoud (Thermal Energy Systems, Department of Mechanical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Master's thesis
Year 2009
Abstract Decreasing the operating temperature in a SOFC allows the use of less complex materials and constructions methods, thus reducing the plant and the electricity cost; with the lowering of the temperature in the SOFC, the use of a bottoming steam cycle instead of a gas cycle in a hybrid SOFC plant could become suitable. In this thesis work, the integration of a Solid Oxide Fuel Cell plant and a steam power plant has been analyzed. Simulations have been carried out using DNA (Dynamic Network Analysis), a component-based simulation tool for energy systems analysis developed in the Thermal Energy Systems department at DTU. Analysis asserts that in an hydrogen fed SOFC, efficiency increases from 47.5 % for the only SOFC plant until 53.2 % for a combined SOFC-single pressure level steam plant, up to 62.8 % if a reheating is used in the steam plant and the inlet SOFC air is pre-heated using the depleted steam generator gases. Net power increases of 30% with reference to the only SOFC plant while a post burning increases the net power until 80 % with an efficiency penalty of 2% with reference to the unfired combined cycle. A methane fed SOFC model has also been simulated: the bottoming steam cycle with reheating increases the combined plant efficiency until 70% against the 54.8 % for the only SOFC plant, if the depleted steam generator gases are used to pre-heat the SOFC inlet air. However, the single pressure level steam cycle without reheating allows getting the same combined plant efficiency as the steam plant with reheating. Analysis has been carried out using also natural gas as a fuel, simulating the adiabatic steam reforming and the catalytic partial oxidation pre-reforming. A partial load analysis for the methane fed plant has been carried out too, reducing the load until the 78 % of the full load: what results is a part load working without any efficiency penalty. Finally, a thermoeconomic analysis of the natural gas fed plant reformed through the adiabatic steam reforming has been carried out: in the actual scenario, the current SOFC cost (without serial production) was set, giving rise to an electricity cost of 0.24 €/kWh. In a future scenario, hypothesizing a considerable lowering of the SOFC cost, analysis asserts an electricity cost of 0.054 €/kWh.
Imprint Technical University of Denmark (DTU) : Kgs. Lyngby, Denmark
Pages 171
Keywords SOFC; steam cycle; CPO; ASR; power plant; hybrid cycles
Fulltext
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Admin Creation date: 2009-06-26    Update date: 2009-11-04    Source: dtu    ID: 245706    Original MXD