Temperature and Auxiliary Controls

For all fuel cells, except those running on high-purity hydrogen, some form of fuel treatment is required. The main problem with fuel supplies intended for conventional combustion systems is the presence of minor contaminants containing ash-making chemicals and sulfur compounds. In fuel cell applications, the sulfur compounds form corrosive substances that poison the catalysts in the reformer stages and the fuel cell itself. 

Therefore, scrubbing is often required. The scrubbing process is not tolerant of water contamination because it can cause the bed to collapse if exposed for prolonged periods to high water vapor pressures or to condensation. Alkaline fuel cells also require the removal of carbon oxides including C02. 

After the scrubbing, water vapor must be added to the scrubbed mix, in order for the shift reaction to properly function in the reformer. The steam 

A simplified flow diagram of a high-temperature fuel cell system. 

268 Post- Oil Energy Technology After the Age of Fossil Fuels 

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