Measurement of Air Pumped Using a Rotary Atomizer in a Spray Dryer

Rotary atomizers are commonly used in spray dryers to atomize feed. One destructive effect of wheel rotation is the creation of a vacuum inside the wheel that conducts hot air from the chamber into the wheel and can lead to atomizer blockage and an explosion. The present work determined the air-pumping characteristics of a rotary atomizer with a 50 mm wheel diameter. The vacuum pressure and power required to pump air was measured, as well as the friction power of the transporting parts, the shear power, and the air pumping power at rotational speeds of 7100-24100 rpm and gaps of 0.5-1.5 mm. Nearly 10% of atomizer power was consumed to pump air, 25% for air shearing, and 65% in the friction between the transporting parts. The results indicated that increasing rotational speed and the size of the gap increased the inlet air rate. This increase was more pronounced for the increase in gap size.