Pneumatic Conveyors

Pneumatic conveyors are used to move grain and other products using air. Pneumatic conveyors are more flexible than augers because the duct does not need to be in a straight line. They are self-cleaning, and do not have an exposed auger at the inlet. They do require more horsepower per bushel and are noisier than augers. Three types of pneumatic conveyors are used: positive pressure (push units), negative pressure (vacuum), and a combination of negative and positive pressure. In a positive pressure unit, a blower supplies the pressure, and the product enters the air stream through a rotary air lock. The material then is blown through the duct, Figure 20.2.

In a negative pressure unit, the material is vacuumed up by the inflow of air and then separated from the air in a cyclone separator. The material collects in the bottom of the separator where it can be released with a gate valve or a rotary lock. The air continues on to the pump and out through a filter into the atmosphere, Figure 20.3.

In a combination system, the material is picked up by the inflow of a negative pressure system, and then it passes through a rotary air lock into the positive pressure air stream coming from the pump.

Material hopper

Material hopper

FIGURE 20.2. Positive pressure pneumatic system.
FIGURE 20.3. Negative pressure pneumatic system.

Was this article helpful?

0 0

Post a comment