Distinction between upward and downward flows in circulating fluidized beds

摘要: Abstract A simple momentum probe was used to distinguish between upward and downward flow regions in risers with diameters of 66, 97 150 mm. Experiments indicated that a typical core-annulus structure existed only above the inflection point corresponding axial voidage profile. In lower dense region, due extensive solids turbulence mixing, no clear observed. dimensionless core radius increased gradually increasing distance from point. The variations thickness downflow region gas velocity, riser diameter circulation rate were investigated. Analysis results radii almost coincide for different operating conditions positions, but at same cross-sectional averaged holdup. An empirical correlation therefore developed describe variation radius, which showed favorable agreement predicted experimental data obtained by present literature studies.