Biomass is considered as one of the most promising alternatives to fossil fuels because of its wide variety of sources, greater overall reactivity in comparison to coal and the potential negative addition in terms of net CO2 emission. Benefiting from an efficient compaction and granulation process, biomass pellet can be produced with a density of 1000-1300 kg/m3 from loose biomass of bulk density 10-20 kg/m3, and the energy density is approximately 3*104 kJ/kg, equivalent to medium coal. Also, there is no obvious dust discharged in thermal conversion process due to the mitigation of fines elutriation. Considering both the economy and safety, pelletized biomass with better fuel properties is more potential for future industrial application. In the light of the high volatile content of biomass, syngas production using gasification has always been a mainstream direction for biomass utilization. Chemical looping gasification (CLG), on the basis of chemical looping concept, is one of the promising gasification technologies, integrating the process of gasification and hot gas conditioning, with the objective to obtain syngas with low tar amount.
Previous studies only focus on the conversion of traditional powdered biomass in CLG process, little attention has been paid to the pelletized biomass. Some understanding gaps including the yield of three-phase (syngas, tar and char) products, the mechanical strength evolution characteristics, the binary mixing evolution characteristics, the chemical reaction kinetics, the heat conduction characteristics and the corresponding simulation during CLG of biomass pellets is still exist.
This research is funded by the DFG (German Research Foundation) (project number 392123414) and the NSFC (National Natural Science Foundation of China) (project number 5171101345).
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, Southeast University, Nanjing, China.