Influence of high-speed jet on the particle distributions in downer

Abstract

The large-scale cold model experiments are carried out to investigate the influence of high-speed jets on the distribution of particles in downer. The cases of both downward jets (co-current contact) and upward jets (counter-current contact) are studied. Generally, it is found that the solid holdups in the initial mixing zone of feed with particles are higher under the influence of counter-current jets, which could form the local “thickening” region in downer. To make a quantitative comparison, the radial non-uniformity index of solid holdups RNI(ε_s) in the jet mixing zone is calculated. Results show that the solid holdups in the counter-current jet mixing zone are more uniformly distributed in radial and the axial jet influence zone is shorter. By changing the jet gas velocity, its effects on the particle distributions are analyzed. Finally, based on experimental data, the distributions of solid holdups in co-current and counter-current jet influence zones of downer are formulated into formulas.