Pneumatic Conveying of Solids

Abstract

Introduction In solids processing systems, it is commonly required to transport solids from one location to another. Solids can be transported via various means, including (1) pneumatic conveying, in which solids are transported in a pipe or channel by gas flow through blowing or suction; (2) gravity chutes, where solids transport downward by gravitational force; (3) air slides, where solids, partially suspended in a channel by the upward flow of air through a porous wall, flow at a small angle to the horizontal; (4) belt conveyors, where solids are conveyed horizontally, or at small angles to the horizontal, on a continuous moving belt; (5) screw conveyors, in which solids are transported in a pipe or channel by a rotating helical impeller; (6) bucket elevators, in which solids are carried upward in buckets attached to a continuously moving vertical belt; and (7) vibratory conveyors, where solids flow is activated by jigging action provided by angled spring supports. This chapter focuses on pneumatic conveying as the means for solids transport. Examples of solid materials that are commonly transported via pneumatic conveying are flour, granular chemicals, lime, soda ash, plastic chips, coal, gunpowder pellets, ores, and grains [Stoess, 1983; Williams, 1983; Konrad, 1986; Soo, 1990; Marcus et al. , 1990]. Materials to be conveyed are usually dry and readily free-flowing. Some sluggish and damp materials can also be free-flowing with proper aeration. The advantages of pneumatic conveying include extreme flexibility in routing and spacing, safe working conditions, and low maintenance cost.