Integration of an adsorptive desulfurization unit into an SOFC-based auxiliary power unit operated with diesel fuel

On-board desulfurization is mandatory for operating solid-oxide-fuel-cell-based auxiliary power units (SOFC-based APUs) with commercial sulfur rich fuels. In this work, the desulfurization and regeneration performance of an Ag–Al₂O₃ adsorbent was evaluated over 5 cycles of operation using a system-integrated thermal regeneration approach. The results from the experimental investigations were further used as boundary conditions to carry out a full integration study of the designed desulfurization unit into a 5.5 kW_el SOFC-based APU. The experimental investigations showed high breakthrough capacities of the Ag–Al₂O₃ adsorbent when desulfurizing a dibenzothiophene-rich diesel fuel. In addition, 100% of the initial breakthrough capacity was restored over 5 cycles of operation by using the hot off-gas of an SOFC-based APU; no sign of performance degradation was observed. Furthermore, the integration study showed that both the temperature and the available volume flow rate of the hot APU off-gas are sufficient to perform on-board regeneration cycles in real SOFC-based APUs similar to those used in the lab-scale experiments.