Minimum fluidization velocity of ground chip and ground pellet particles of woody biomass

The present work reports the hydrodynamic properties of ground chip (GC) and ground pellet (GP) particles of pine wood. Ground particles are made by grinding whole wood chips and whole wood pellets in a hammer mill equipped with a 3.2 mm screen. The average diameter of the particles measured by using image processing is 0.75 nun for GC particles and 1.31 mm for GP particles. The average density of particles is 1.33 g/cm(3) for GC and 1.43 g/cm(3) for GP. Pressure drop versus the air flow across a bed of particles is measured and the parameters of Ergun equation are estimated. GP particles have a minimum fluidization velocity of 15.2 cm/s which is much higher than the minimum fluidization velocity of GC particles at 8.5 cm/s. Both GC and GP particles undergo channeling and bed separation during fluidization. No bubbling regime was observed.