Determination of biomass char combustion reactivities for FBC applications by a combined method

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