Study of hydrodynamic characteristics of sawdust in a circulating fluidized bed

Hydrodynamic characteristics of sawdust were investigated in a circulating fluidized bed (CFB) with height of 10m and inner diameter of 0.28 m. Experiments were carried out to study the axial and radial distributions of particle velocity and bed voidage along the riser under the conditions of superficial velocity U_g=1.81~2.26 m/s, particle circulation rate G_s=0.42~0.76 kg/(m²·s). The results show that stable operation of the CFB can be obtained if sufficient materials are kept in the downcomer; particle flow in the riser shows a typical core-annulus structure; average bed voidage goes up first and then down along with bed height; flow characteristics along the riser of core, transition and annulus area can be obtained by dividing the cross section into three areas with r/R=0~0.71, 0.71~0.93 and 0.93~1.00.