Flash Dryers

Flash dryers offer an effective method of removing surface or unbound moisture from a feed product. The technology behind flash drying employs a low residence time within the actual dryer; thus, the unbound moisture is "flashed" off the feed. Flash, pneumatic, ring dryers, flash tube, or cyclone dryers use a heated carrier gas (usually, air) to pneumatically convey the feed through the flash dryer (flash tube) and into a primary gas-separation device (most commonly, a cyclone or series of cyclones in series or parallel). The carrier is induced or forced into the feed throat from a hot gas generator that heats the gas to the desired operating inlet temperature. In the feed throat, the gas entrains the feed and the moisture is evaporated quickly as the product is conveyed through the system to the primary gas / product separation device. Because the entire product is entrained in the gas stream, both primary product collection (typically, cyclones) and secondary and tertiary dust collection such as multicyclones, bag houses, scrubbers, and electrostatic precipitators usually are installed to meet emission limits. Flash dryers are an efficient method of drying products such as slurries, pastes and sludge (most with back mixing), friable filter cakes, powders and granules.