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 CO2 from syngas to from CaCO3, 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 H2 yield grew from 0.103 to 0.256Nm3/kg at 800.0celcius, and the CO yield boosted from 0.158 to 0.317Nm3/kg. Multiple redox manifested that the SA oxygen carrier and calciumbased 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.

Automated summary

Chemical-looping gasification tests were performed on pine sawdust with an iron-rich sludge ash oxygen carrier, investigating the influence of a calcium-based additive. The study analyzed the impact of temperature, CaO/C ratio, multiple redox cycles, and CaO addition modes on gasification performance. The results showed that CaO effectively captured CO2, forming CaCO3, which decomposed at high temperatures. Increasing CaO/C ratio resulted in higher H2 and CO yields in the syngas. Multiple redox cycles demonstrated higher reaction stability with the oxygen carrier and calcium-based additive. Possible reaction mechanisms indicated that the variation in syngas from BCLG was influenced by the role of calcium and the valence change of iron.