Effect of secondary gas injection on the particle entrainment rate in a gas

Abstract

The efl~ct of secondary gas injection on the particle entrainment rate was measured in a cold model fluidized bed (i.d. 0.l m, height 2.25

m) and discussed. Sand particles below 0.425 mm in screen size were used as bed materials. The particle size (0.128-0.363 mm), the overall

superficial gas velocity (0.78-2,76 m/s). the secondary gas fraction (0-0.5), and the static bed height (0.1-0.3 m) were considered as

experimental variables. The panicle entrainment tale decreased with an increase of the secondary gas fraction. The injection level of the

secondary gas was shown to have an important influence on ils effect. The effect of the secondary gas was appreciable for over-bed injection;

Ihe effect was reduced, however, when the injection level was placed in the splash zone or in the dense phase by means of increasing the bed

height.