Study on counter-flow steam gasification characteristics of biochar with Fe2O3/CaO in-situ catalysis in fixed bed

Abstract

It is important to explore a relatively cheap and efficient biomass steam gasification process for the high-value utilization of biomass. Biochar was used as raw material for steam gasification, and the steam gasification of counter-flow biochar fixed bed was enhanced by the in-situ catalysis of Fe2O3 and CaO. By changing the steam flow rate and heating temperature, the operating characteristics of counter-flow gasification were explored and compared with updraft and downdraft gasification.The experimental results show that the addition of CaO in counter-flow gasification can improve the gasification intensity of biochar at lower temperature and steam flow rate. At 750 ℃, the biochar loaded with CaO at steam flow rate of 3.75 ml/min has a maximum heating temperature LHV of 11.49 MJ/Nm3. As the heating temperature increases, the hydrogen production yield gradually decreases. At temperature of 850 ℃ and steam flow rate of 3.75 ml/min, the gasification intensity of CaO loaded biochar was 66.44 % higher than that of unloaded biochar, and the gasification intensity was increased by 15.04 % by loading Fe2O3. However, the addition of Fe2O3 can improve the hydrogen production yield of biochar. At 850 ℃ gasification temperature, the hydrogen production yield is 23.25 % higher than that of biochar without catalysis.