Utilization of Bio-Syngas in Solid Oxide Fuel Cell Stacks: Effect of Hydrocarbon Reforming

Abstract

We report on state-of-the-art JÜLICH (Forschungszentrum Jülich) stack with anode-supported solid oxide fuel cells (AS-SOFCs) that have been tested in bio-syngas derived from wood pellets. The sulfur and chlorine were removed after gasification, but the tars were not reformed in the bio-syngas to study the influence of these tars on the degradation of SOFC stack. The total tar content during test was 3.5 g/Nm 3 including benzene, toluene, phenol, m-cresol, naphthalene, and minor traces of undefined tars. The test result shows considerable performance degradation in tar-contaminated syngas. Moreover, the test was stopped after 5 hours of operation due to an increase of the pressure drop in the stack. A post-test analysis was carried out, and heavy carbon deposition was found at the cell anode-support surface and the Ni mesh current collector. Carbon was identified by SEM as numerous carbon fibers. The change of support microstructure was also observed near and under the carbon deposition area, and the dusting of Ni metal was observed in the support and Ni mesh current collector.

Effect of internal hydrocarbon reforming during coupled operation of a biomass gasifier with hot gas cleaning and SOFC stacks

“…Detailed analysis of the microstructure of Stack B showed that the substrate was unaltered in areas toward the outlet of the cells. In areas with brighter color, loss of connectivity between Ni and YSZ could be observed.…”

Flexible biomass conversion to methanol integrating solid oxide cells and TwoStage gasifier

“…The studies revealed that the Ni-GDC SOFC electrode operates successfully with low fuel utilization factor (UF) and sufficient steam. Conversely, Jeong et al [68] and Geis et al [69] noted carbon deposition, followed by metal dusting during their test campaigns when Ni-YSZ SOC operated at 700 °C. This phenomenon was not predicted by thermodynamics.…”

Flexible methanol production units coupling solid oxide cells and thermochemical biomass conversion via different gasification technologies

“…Short-term experimental campaigns showed that SOC stands operation on a tar-containing stream (above 10 g/Nm 3 ) at high temperatures (~800-850 °C) [46,47]. Conversely, other tests showed that SOC at lower temperatures (~700 °C) encounters difficulties [48,49]. In general, SOC operating temperature, SOC electrode composition and composition of the tars play an important role for the lifetime of the SOC operated on tar-laden gas.…”