Drying Desk: Flash drying close up
At first glance, flash drying might appear to be so simple that nothing much needs to be said about it. After all, the flash dryer is merely a pneumatic conveying duct through which wet feed comes into contact with heated air, resulting in moisture evaporation during conveying. However, several design details are important to successful flash drying.
A flash dryer’s typical air conveying velocities are from 3,000 to 6,000 fpm, depending on the material’s size, shape, and specific gravity. The drying column length can range from 30 to 150 feet. The resulting contact time in the drying column is only 0.3 to 3.0 seconds. In fact, there’s probably more contact time in the dried product collector.