Performance in Coupled Fluidized Beds for Chemical Looping Combustion of CO and Biomass Using Hematite as an Oxygen Carrier

A system of coupled fluidized beds for chemical looping combustion was successfully conducted using CO and biomass as fuel. A multi-stage fluidized bed was designed as a fuel reactor to improve gas-solid contact. In the experiments, iron ore was used as the oxygen carrier. The effects of operation parameters, such as fuel reactor temperature and feeding rate, were studied. This reactor can convert gas fuel, CO, into CO2 efficiently in the temperature range of 840-900 degrees C with different inputs, and the conversions of CO are almost above 90%. For biomass experiments, the fuel reactor temperature exhibits positive effects on the fuel conversion and carbon capture efficiency. The carbon conversion and carbon capture efficiency reach 92.5 and 98.5% at 900 degrees C, respectively. The temperature above 880 degrees C is optional for the biomass combustion in this reactor. Besides, the feeding rate has small influences on the carbonaceous gas conversion. In comparison to previous work, this reactor shows superiority in terms of carbonaceous gas conversion, especially at a high temperature, and the carbonaceous gas conversion efficiency reaches 95.4% at 920 degrees C. At last, the used oxygen carrier is characterized, and no sintering signs appear on the surface of the oxygen carrier. In conclusion, this new facility can be a candidate for the application of chemical looping biomass combustion.