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A: Flash drying, also called “pneumatic drying”, is the rapid, almost instantaneous, removal of moisture from wet solids by dispersion in a high velocity hot gas stream. Typically, air velocities range between 2,500 and 5,000 feet per minute, and residence times are usually less than a second. |
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The product is completely dispersed in, and surrounded by, a hot gas that pneumatically conveys the product through the system. Because residence times are short, this type of drying is usually limited to products that require the removal of unbound or surface moisture (i.e., easily removed moisture). However, because the particles are usually very small, even internal moisture can be removed in flash drying systems, depending on how tightly it’s bound.
Fluid Energy’s ThermaJet dryer is a recirculating loop flash dryer, also known as a ring dryer, making it very compact compared to other driers. The wet product is introduced into a turbulent, hot air stream created by sonic velocity nozzles resulting in deagglomeration and drying. Due to centrifugal forces, wetter, larger particles are kept to the outside of the ring, where they can be recirculated back into the turbulent zone for further processing. The fine, dry powder is removed and sent to the product collection device(s).
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