A reformer to generate hydrogen for distributed power applications
The generation of power using fuel cells is a promising technology for distributed electric power generation applications. Steam reforming of fossil fuels remains the most thermodynamically efficient means for production of hydrogen. Unfortunately, current steam reforming technology achieves high efficiencies only at very large scales, and remains impractical at the small production rates needed for small- to medium-size distributed power applications. A novel reformer process, called unmixed reforming, or UMR, has been developed for the conversion of hydrocarbon fuels (natural gas, diesel, gasoline) to hydrogen. The reformer promises high thermodynamic efficiency as heat is generated right on the catalytic bed unlike conventional reforming. The controlled combustion on the reforming catalyst using a patented technology called unmixed combustion provides the heat for the endothermic reforming reaction. The reformer generates a high-purity hydrogen product stream, which can then be used by fuel cells with minimal processing. The unmixed reformer is a packed-bed consisting of finely divided nickel supported on a ceramic matrix mixed with a calcium oxide bearing matrix such as dolomite. UMR consists of three process steps. During the first step air is passed over the packed-bed reactor to oxidize the nickel. The heat released during the oxidation reaction raises the temperature of the bed and decomposes the dolomite releasing carbon dioxide into a vent gas stream. In the subsequent step fuel passed over the packed-bed reduces the NiO back to Ni and further increases the temperature. In the final step, fuel and steam react to produce hydrogen through conventional steam reforming chemistry. The calcium oxide captures some of the carbon dioxide formed during the reforming reaction and thus shifts the reforming reactions to higher conversions, hence improving the purity of the hydrogen product stream. Although product hydrogen concentrations may be 75--85%, the CO content typically averages about 5%. A relatively small water-gas shift reactor can be used to further increase the purity of the product hydrogen and to reduce the CO in the product stream. Final cleanup of the product stream can be accomplished with pressure swing adsorption or selective oxidation of carbon monoxide.
- Research Organization:
- Energy and Environmental Research Corp., Irvine, CA (US)
- OSTI ID:
- 20002727
- Resource Relation:
- Conference: 33rd Intersociety Energy Conversion Engineering Conference, Colorado Springs, CO (US), 08/02/1998--08/06/1998; Other Information: 1 CD-ROM. Operating system required: Windows 3.x; Windows 95/NT; Macintosh; UNIX. All systems need 2X CD-ROM drive.; PBD: 1998; Related Information: In: Proceedings of the 33. intersociety energy conversion engineering conference, by Anghaie, S. [ed.], [2800] pages.
- Country of Publication:
- United States
- Language:
- English
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