Analysis and Optimization of a Hybrid MCFC-Steam Turbine Plant

Fuel Cells are high efficiently chemical energy conversion devices and their promising high performance are recognized by all the scientific community. Their conversion efficiency can be further enhanced recycling the heat content of the exhaust gas for CHP applications or for a bottoming cycle. For this kind of application, high temperature fuel cells (MCFC and SOFC) particularly suit, because outlet gas temperature is relatively high. In previous works (Desideri U. et al. 2001, Lunghi P. and Ubertini S. 2001, Lunghi P., Bove R. and Desideri U. 2002) the possibility of combining an ambient pressure MCFC with a gas turbine has been deeply investigated. Results showed very promising performance only if new designed turbines will be available for an optimised plants combination. The inlet temperature for gas turbine, in fact, is sensible higher than exhaust gas from fuel cell anode and so additional fuel is needed in the bottoming cycle, leading a system efficiency reducing. For this reason, in a previous work (Lunghi P. and Bove R. 2003) it was analyzed the possibility using as bottoming cycle a Steam Turbine Plant equipped with a HRSG for steam generation. In the present work suitable MCFC and Steam Turbine sizes are chosen and a performance analysis is conducting, through numerical simulations. Results showed very high electric efficiency reachable with this plant configuration.Copyright © 2003 by ASME