COMPARATIVE ANALYSIS OF FLUIDIZED AND FIXED BEDS TO OBTAIN DATA ON THE CHAR PELLET'S COMBUSTION REGIME

Three different types of biochar particles were made from fixed bed carbonization at 800°C of pellets produced with Pinus Pinaster, Acacia dealbata, and Cytisus scoparius. From the fluidized bed combustion of batches of these biochar particles at three different bed temperatures, 700, 800, and 900°C, kinetic and diffusive data were determined. Subsequently, batches of the same biochar particles were burned in a fixed bed, also for the same three bed temperatures of 700, 800, and 900°C. Through a mathematical model for combustion of batches of biochar particles in a fixed bed, combined with the kinetic data previously obtained through the fluidized bed combustion experiments, data concerning the fixed bed combustion was determined, namely, the in-bed interparticle competition factor for the available oxygen and the constriction factor. The relative importance of the in-bed diffusion, the heterogeneous reaction rate kinetics, and the bed fluid dynamics in fluidized and fixed bed combustion was also evaluated.