Determination of biomass char combustion reactivities for FBC applicationsby a combined method

Combustion reactivities of five wood chars were measured at 300-900 degrees C to produce suitable kinetic data to mass balance equations of a fluidized -bed combustion model. Two different techniques were used: char burnout tim e measurements in a fluidized-bed reactor and low-temperature char reactivi ty measurements in a thermogravimetric analyzer (TGA). A combined method is proposed here to avoid the limitations of both experimental techniques, es pecially for very reactive chars. In this method, the intrinsic activation energy for each char was determined in TGA at low combustion temperatures a nd the pre-exponential factor was obtained by fitting the experimental valu es of burnout times. Good agreement between experimental and calculated res ults was achieved.