Holistic assessment of oxygen carriers for chemical looping combustion based on laboratory experiments and validation in 80 kW pilot plant

By utilization of biomass for chemical looping combustion, negative CO2 emissions are possible, but with solid fuels also special requirements are immanent. In particular, the oxygen carriers an important process resource, must handle high temperature operation, while retaining good reaction kinetics and oxygen transport capacity. The focus of this work lies on the development of a fast and cost-effective characterisation scheme of oxygen carriers under operational conditions for dual fluidized beds in order to achieve an assessment for the comparability of different materials. For this purpose, three oxygen carrier were investigated in detail in a laboratory-fluidized bed and compared with operation in an 80 kW pilot plant. By classifying the oxygen carrier into fluidized bed material properties and carrier-properties, a ranking and assessment of ilmenite, braunite and a further manganese ore could be achieved. The tests showed that bed material properties such as attrition, density and bulk density must be given higher priority. These findings were confirmed by operation in an 80 kW pilot plant, where ilmenite achieved a carbon capture rate above 98% and a CO2 yield at almost 89%. The results show that the evaluation and estimation of operation in the 80 kW pilot plant is possible via the laboratory plant experiments.