(55b) Conversion of High Sulfur Fuels to Synthesis Gas for Fuel Cells

The conversion of military fuels to synthesis gas (i.e. hydrogen and carbon monoxide) that can be used by fuel cells of any type is a difficult process. While solid oxide fuel cells (SOFC) are capable of using both hydrogen and carbon monoxide, the cells are still sensitive to the sulfur in the military fuel. In addition, the military fuels are generally a mix of heavier hydrocarbons that can generate carbon if the reactions are not in the proper regime.

This paper will describe a non-thermal plasma reformer that generates a stream of synthesis gas appropriate for a SOFC auxiliary power unit from an input of military grade diesel fuel (e.g. JP8). Military fuels such as JP8 can contain up to 3000 parts per million sulfur. Typical catalytic based reformers are also sensitive to sulfur requiring the removal of sulfur by hydro-desulfurization or a liquid phase sulfur removal step. The non-thermal plasma approach has the advantage that it is not sensitive to sulfur. The non-thermal plasma acts in much the same way as a conventional catalyst to promote the reforming of the fuel but does not deactivate over time. It is in effect a constantly renewing catalyst.

Under proper conditions the non-thermal plasma can also be used to disassociate hydrogen sulfide into hydrogen and elemental sulfur. Using a cascade effect it is possible to reduce the amount of sulfur transmitted to the SOFC portion of the system to an amount that can be tolerated by the SOFC. This process will also be described in the paper.