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DESULFURIZATION OF JET FUEL AND MARINE GAS OIL FOR APPLICATION IN
MOBILE FUEL CELL SYSTEMS
by Jochen Latz
ABSTRACT
Fuel cells are well suited for generating on-board power supply in aircraft, ships and heavy
goods vehicles to improve the energy efficiency and to cover rising demands for electrical
energy. In order to operate fuel cells with the fuels available on board, the fuel is converted
into a hydrogen-rich gas by a process of catalytic reforming. Since both the catalysts in the
reformer and also in the fuel cell are deactivated by the sulfur compounds contained in the
fuel, the fuel must be desulfurized.
Whereas diesel fuel for road vehicles within the EU is already desulfurized at the refinery, jet
fuel is permitted to have up to 3000 ppm of sulfur worldwide and marine gas oil for fuelling
vessels on inland waterways can contain up to 1000 ppm in the EU. Consequently, on-board
desulfurization is required for the use of fuel cell auxiliary power units (APUs) on aircraft and
ships. Since the hydrodesulfurization process used in refineries is not suitable for mobile
applications, the present work had the aim of developing alternative processes and determining
their technical feasibility.
To this end, a large number of processes discussed in the literature were assessed with respect
to their application in fuel cell APUs and four potentially suitable processes selected for
detailed investigation. Laboratory tests revealed that adsorption in combination with separation
by means of distillation or pervaporation is a suitable process for the desulfurization of jet
fuel. Additionally, hydrodesulfurization with presaturation provided convincing results on a
laboratory scale.
In order to verify the technical applicability of fuel cell APUs, three desulfurization processes
were assessed with respect to energy demand, size and durability. Of these processes, hydrodesulfurization
with presaturation provided the best results. Whereas the technical application
of the process consisting of adsorption and pervaporation requires further research
work, the process of adsorption and separation by means of distillation is not economically
feasible, above all due to the high energy demand.
Finally, the technical applicability of hydrodesulfurization with presaturation was demonstrated
in a pilot plant for a fuel cell APU with a power of 5 kWel, going beyond the laboratory
scale. The aim of developing a suitable process for the desulfurization of jet fuel in fuel cell
APUs has thus been achieved.
However, the investigations on marine gas oil showed that desulfurization in fuel cell APUs is
not possible at present even with the alternative desulfurization approaches currently available.
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