Study of Swirling Pneumatic Transport of Granule in a Horizontal Pipe.

Abstract

Pneumatic transportation for fragile materials and tablets is a big challenge in pharmaceutical industry. The horizontal pneumatic conveying of granules was experimentally performed in order to investigate the effect of spiral flow on the granule destruction. The spiral flow used is weak and the maximum circumferential velocity is about 2.2m/s and the maximum swirl number is 0.03 when the mean air velocity is 30m/s. It was found that the spiral flow is effective to reduce the damage at lower air velocity as the mass flow rate of granule is increased. A numerical simulation showed that the number of collision between granule and pipe wall in the spiral flow is larger than that in the rectilinear flow but the kinetic energy of granule that comes in collision with the pipe wall is smaller in the spiral flow than in the rectilinear flow. It is inferred that the spiral flow makes the granules move along the pipe wall to reduce the kinetic energy of granule below the threshold of granule strength for destruction.