A comprehensive three-dimensional numerical model including the kinetic theory of granular flow and complicated reactions was developed to simulate the chemical looping combustion process in the fuel reactor. The standard kÀε model was used to simulate the gas-phase turbulence and the kinetic theory of granular flow to simulate the solid phase. The shrinking core model (SCM) with the reaction controlled by the chemical reaction in the grain was applied. The fuel reactor was designed as a bubbling fluidized-bed reactor with a height of 1.2 m and diameter 0.1 m. A Cu-based oxygen carrier was prepared with 14 wt % CuO on 86 wt % inert Al 2 O 3 . The inlet fuel gas was coal gas containing 44.5 vol % CO, 22.2 vol % H 2 , 22.2 vol % H 2 O, and 11.1 vol % CO 2 . The flow patterns, distributions of gas components, and conversions of gas reactants were obtained. The effects of the operating conditions (the initial bed height, bed temperature, and operating pressure) on fuel conversion were analyzed. The results show that the fuel conversion with the same inlet gas velocity would go up by modestly increasing the initial bed height and the temperature but would slightly decrease with an increase in the operating pressure. The high conversion of coal gas with a low solid inventory could be reached in a proper operating condition.

As a result of the increasing transport cost of biomass and benefiting from the more efficient treatment of a compacted, dustless product, the use of pelletized biomass has gained interest over recent years in China. Chemical looping gasification (CLG) with circulating oxygen carriers provides a novel process, which integrates biomass gasification with the hot gas conditioning with the aim to obtain pure syngas with a low tar amount. The study focuses on the CLG application using a single typical rice husk pellet as fuel, which is characterized by high silicon dioxide in ash. Some experiments in a fluidized bed unit with the mixture of quartz sand and an active manganese ore as bed materials were performed using a single rice husk pellet as fuel and steam as the gasifying agent. The objectives of the work are to investigate its CLG performance and bottom ash characterization. Effects of the gasification temperature (750–950 °C) and oxygen carrier/fuel ratio on syngas distributions, effective gas content, and syngas yield were investigated. The conversion of the rice husk pellet is very dependent upon the reaction temperature. A high temperature promoted tar cracking and gasification reactions, leading to a fast carbon conversion. The effective gas content (CO + H2 + CH4) during the gasification process was in the range of 74.2–79.9% under the temperature of 750–950 °C. With regard to the CLG application of a rice husk pellet as fuel, much attention should focus on bottom ash, which was not separate during the process but still kept the original pellet shape, with some irregular pores inside the ash as a result of the formation of molten grains. The ash demonstrates a rigid skeleton-like structure. The trapped carbon particles inside the molten ash cannot be gasified, thus limiting the fuel conversion.

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