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10kW demonstration of pilot stack technolgy for direct internal reformingmolten carbonate fuel cell (DIR-MCFC) power plants: final report June '93 to December '95
Gepubliceerd door: Publicatie datum:
ECN 1996
ECN publicatienummer: Publicatie type:
ECN-C--96-023 ECN rapport
Aantal pagina's: Volledige tekst:
40  Niet beschikbaar.

The objective of the title project was to develop the technology forDIR-MCFC for efficient energy production and to demonstrate this technology in a sub-scale stack of 10 kW nominal output power. A set of 4 independent variables was introduced to describe the DIR-MCFC system. Operating ranges were defined in terms of these variables, satisfying interface conditions between stack and balance of plants (BOP) regarding the H2 concentrations at the anode side, and the CO2 and O2 concentrations at the cathode side. A configuration for a 250 kW DIR-MCFC system was selected based on simplicity and efficiency (48% Lower Heating Value or LHV). A cost estimate of this system was also made. Catalyst research showed that even at large alkali uptake (up to 9 wt%), the BG catalyst is still sufficiently active for steam-reforming in an MCFC environment. The alkali shield work has made clear that alkali shields are not feasible in MCFC stacks due to the large calculated performance loss (12%). However, they proved to slow down the carbonate transport towards the catalyst. A 3D model for a DIR-MCFC stack was developed, which takes into account the cell reactions, the flow distribution to and from the cells, the horizontal and vertical heat transport, heat exchange between cell hardware and manifold system and heat losses to the surroundings. Compared to ER-MCFC stacks, DIR-MCFC stacks give large temperature variations in both the planar and stacking directions, thus reducing the achievable stack height and the design temperature difference between outlet and inlet gases. Small-scale (100 cm2) experiments have been performed under a variety of test conditions, in order to obtain information on the interface conditions and to test the cell performance at system conditions. Three-cell stack experiments have been performed on 0.1 m2 cells to test the initial (1st test) and long-term (2nd and 3rd test) behaviour of the DIR separator plate concept. Though high electrical power output (>100 mW/cm2) was demonstrated, the sealing properties of this concept have to he further improved. 4 figs., 4 tabs., 46 refs.

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