B2-SH5A nveyors Dumping devices Caterpillars Bucke Bevel-helical speed reducer B2

Flender/Flender Gear Units/Bevel-helical speed reducer B2

ld dry air either into the outlet end of the dryer or to the dryer walls to cool them to 3 5C (. wide range of fruit and vegetable powders can be dried, agglomerated, and instantized in spray drying units specially equipped with an internal static uidized bed,integral lter, or external vibrouidizer (. Bananas, peaches, apricots, and to lesserextent citrus powders are examples of products dried by such techniques. typical spray drying unit consists of large-volume drying chamber, feed atom- izer, hot air supply, and dry product recovery/dust collection systems. Three consecutivesteps of the process can be distinguished: () atomization of the feed, () spray air mixingand moisture evaporation, and () separation of the dry product from the exit air. Atomization is the most critical operation in the spray drying operation. Three gen- eral types of atomizers are available with many other individual developments. The most commonly used are rotary wheel atomizers and single-uid pressure nozzle atomizers. Pneumatic two-uid (compressed air/liquid feed) nozzles are used rarely in very special applications (slurries, pastelike materials, etc.). Cocurrent, countercurrent, or mixed owof the droplets and drying air is typical in spray drying chambers. The geometrical proper- ties of the drying chambers depend mainly on the type of atomizer used. They are generally short and wide (conical type) for rotary wheel atomizers and long and narrow (tall type) 6 Grabowski et al. Fig. 9 Principles of drying of the slurry in spouted bed of inert particles. (Modied from Ref. 3.) for nozzle atomizers. The dry product is collected at the bottom of the drying chamber and/or in cyclones, bag lters, or electrostatic precipitators. The nal wet separation ofthe powder from the exhaust air is provided in wet scrubbers, wet cyclones, or irrigatedfans (5,. Some spray drying systems, equipped with special atomizing devices, areused for drying pastelike materials such as fruit and vegetable c