Flash dryers offer an effective method of removing surface or unbound moisture from a feed product. Flash dryers are essentially pneumatic dryers. Many variations or configurations have been developed, but all flash dryers employ the same basic concept of operation. The feed must have a relatively consistent particle size to allow for transfer without segregation and buildup. Depending on throughput, they may be small, unnoticed pieces of equipment located inconspicuously in the plant, or they may require large, independent structures for support.
Flash drying is a continuous process with the dryer being either directly or indirectly fired.
They are inherently cocurrent dryers with the hottest air contacting the wettest product. Because the system has relatively low residence time and the moisture is flashed off, a significant amount of evaporative cooling takes place in the system. This allows higher inlet temperatures to be used than in many other dryers without unduly heating the product. Higher inlet temperatures also increase the overall dryer efficiency. Unlike the descriptive name of most dryers such as rotary, spray or conveyor, flash drying refers to the mode of drying rather than the type of equipment.