Abstract
Thermodynamic parameters of chemical reactions in the system were carried out through thermodynamic analysis. According to the Gibbs free energy minimization principle of the system, equilibrium composition of the reactions of chemical-looping gasification (CLG) of biomass with natural hematite (Fe2O3) as oxygen carrier were analyzed using commercial software of HSC Chemistry 5.1. The feasibility of the CLG of biomass with hematite was experimental verified in a lab-scale bubbling fluidized bed reactor using argon as fluidizing gas. It was indicated the experimental results were consistent with the theoretical analysis. The presence of oxygen carrier gave a significant effect on the biomass conversion and improved the synthesis gas yield obviously. It was observed that the gas content of CO and H2 was over 70% in CLG of biomass. The reduced hematite particles mainly existed in form of FeO. It was showed that the reduction of natural hematite with biomass proceeds in a stepwise manner from Fe2O3 →Fe3O4→ FeO. Reduction product of natural hematite can be restored the lattice oxygen by oxidation with air.
Highlights
Chemical-looping gasification (CLG) is a novel gasification technique that involves the use of oxygen carrier, which transfers oxygen from air to the fuel, which is partially oxidized into H2 and CO, avoiding the direct contact between them
Based on the thermodynamic analysis, the mass of oxygen carriers and biomass material were set to 150 g and 44 g in a single test, respectively
H2 concentration increased with the reaction time going on in the chemical-looping gasification (CLG) of biomass probably owing to a part of biomass was totally oxidized into CO2 and H2O which subsequently accelerated the hydrogen generation reactions taking place rightward
Summary
Chemical-looping gasification (CLG) is a novel gasification technique that involves the use of oxygen carrier, which transfers oxygen from air to the fuel, which is partially oxidized into H2 and CO, avoiding the direct contact between them. There are some works studying chemical looping gasification of solid fuels He et al [6] investigated the CLG of biomass with natural hematite as oxygen carriers in a bubbling fluidized bed reactor. Efficiency of the system was as high as 87.49%, and the hydrogen concentration was found to be 71%, in addition, zero discharge of CO2 can realize. The objective of this investigation was to explore the possibility of using natural hematite (Fe2O3) as the oxygen carrier in CLG of biomass. The thermodynamics of biomass chemical looping gasification was analyzed, and the same time, CLG of biomass with natural hematite as oxygen carrier was experimen-. Tally investigated in a lab-scale bubbling fluidized bed reactor using argon as fluidizing gas
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