Experimental investigation on biomass gasification using chemical looping in a batch reactor and a continuous dual reactor

Biomass gasification using chemical looping (BGCL) is an innovative biomass gasification technique using lattice oxygen from oxygen carrier. The present work selected natural hematite as oxygen carrier, and experimental results from batch reactor and continuous reactor were compared in this work. The results showed that the presence of hematite would accelerate the process of biomass gasification and enhance carbon conversion rate, and hematite could increase the heat-carrier capacity of bed materials in the continuous reactor. In the batch reactor, carbon conversion efficiency and fraction of CO + H2 increased within the temperature range of 750-900 °C. However, syngas yield in the continuous reactor reached the maximum of 0.64 Nm3 kg−1 at 850 °C. Besides, the effect of hematite fraction on the gasification performance was similar between the batch reactor and the continuous reactor. When hematite fraction was exceed 40 wt.%, higher hematite fraction resulted in higher carbon conversion efficiency and lower syngas production. At last, the phase characterization of reduced hematite was investigated. Fe3O4 were the main reduced phases of hematite in the batch reactor, while FeO might be existed in the continuous reactor.