Optimizing performance of iron-rich sludge ash as cost-effective oxygen carrier by calcium-based additive for syngas production from biomass chemical-looping gasification.

Chemical-looping gasification tests were conducted on pine sawdust using thermogravimetric analyzer and horizontal sliding resistance furnace to investigate the regulation effects of calcium-based additive on iron-rich sludge ash oxygen carrier. The impacts of temperature, CaO/C in mole, multiple redox cycles, CaO addition modes on gasification performances were analyzed. The TGA results indicated that the CaO addition could effectively capture CO from syngas to from CaCO, which subsequently decomposed at high temperatures. From in-situ CaO addition experiments, the temperature rise resulted in higher syngas yields, while a decrease in syngas LHV. With the CaO/C growing, the H yield grew from 0.103 to 0.256Nm/kg at 800.0℃, and the CO yield boosted from 0.158 to 0.317Nm/kg. Multiple redox manifested that the SA oxygen carrier and calcium-based additive kept higher reaction stability. The possible reaction mechanisms showed that the syngas variations from BCLG were influenced by the calcium roles and valence change of iron.