The role of entrained air from the top of the aerated bin in the discharge of cohesive powder

Abstract

The effect of aeration was investigated as strong wheat flour is discharged from the orifice of open bins. If the orifice diameter is small, part of the aeration air will escape from the top of the bin, and there will be no further increase in powder discharge rate. If the orifice size is large, the additional air is entrained from the top of the bin by accompanied aeration air, and then the discharge rate will increase. The airflow at the top of the bin was estimated by two models. Two aeration methods were investigated: from the conical hopper wall and from the flat bottom. The aeration air was varied in the range up to 30L ∙ min −1 . The diameter of the cylindrical bin was 284 mm, the diameter of the orifice varied from 10 mm to 50 mm, and the flour was not discharged without aeration when the diameter was below 50 mm. • The air entrainment is estimated by two models and confirmed their correspondence. • Two aeration methods were investigated from the conical hopper and the flat bottom. • A part of the aeration air will escape from the top of the bin. • The additional air is entrained from the top of the bin by accompanied aeration air. • The driving force to the particles at the orifice collapses the static arch formation.