Energy Integration of the Steam Reforming Process of Bioethanol And Fuel Cells

JAVIER FRANCESCONI,; MIGUEL MUSSATI,; ROBERTO MATO,; AGUIRRE, PIO

Rio de Janeiro

Congreso; 2nd. Mercosur Congress on Chemical Engineering. 4th. Mercosur Congress on Process System Engineering; 2005

Fuel cells are being considered a promising alternative to the propulsors in transport vehicles in the next future since they operate at higher efficiencies and produce low environmental impact. The aim of this work is to investigate the synthesis and energy integration of a fuel processor for hydrogen production. Steam reforming of bioethanol and hydrogen purification process are coupled to a polymeric fuel cell (PEMFC). The hydrogen processors consist mainly of three fixed-bed catalytic reactors; the first is a fuel reformer and the other ones are used for reducing impurities, mainly CO, which affect the system operation and deteriorate the cell. A commercial simulator was used to solve the mass and energy balance, and to compute the operative conditions for the process units. The highest energy consumption is demanded by the reforming reactor, which operates at the highest thermal level. It is needed to preheat, evaporate and re-heat the feed stream, and to provide the reaction heat. To obtain an efficient integration, the heat exchanged between the reformer outcoming streams of higher thermal level (reforming and combustion gases) and the feed stream, should be maximized. The operation at high temperatures diminishes the processor efficiencies. Another process variable that affects the process efficiency is the water-to-fuel ratio fed to the reformer. The water excess must be evaporated and re-heated consuming additional fuel in the reformer, diminishing then the system efficiency.