Drum dryers performance

Five key variables influence the drum dryer performance. They are (1) steam pressure or heating medium temperature (2) speed of rotation (3) thickness of film (4) feed properties (e.g., solids concentration, rheology, temperature, etc.) and (5) method of removing dust flakes by scraper or knife. Because they allow control of the temperature, drum dryers may be used to produce a precise hydrate of a chemical compound rather than a mixture of hydrates. 

Perforate basket centrifuges, 16 660 operation, 5 529, 543-545 Perforated bowl centrifuge, theory of performance, 5 515 Perforated-drum dryers, 9 120 Perforated-plate columns, 10 772-774 Perforated plates, 11 810 Performance. See also Filter performance of BJTs, 22 248-249 of FETs, 22 165... 

TABLE 9.11. Performance Data of Drum Dryers (a) Drum Dryers... 

Vallous, N.A., Gavrielidou, M.A., Karapantsios, T.D., and Kostoglou, M., Performance of a double drum dryer for producing pregelatinized maize starch, J. Food Eng., 51,171,2002. 

The evaporative capacities in Table 37.3 are somewhat higher than the corresponding values given by Stewart [75] for fleece wool dryers, namely, 10-15 kg m 2 h" for belt (or brattice) dryers and 20-30 kg m h for suction-drum dryers. However, Stewart s figures probably relate to older dryers of lesser performance. The electrical power use for brattice dryers is less than that for units involving rotating drums, being about 250 kJ kg > (evaporation) for the band driers and 400 kJ kg- for the drum dryers. However, the latter is still only about 12% of the thermal load. 

Kudra and Ratti (2006) performed an energy and cost analysis of convective drying (belt conveyor and drum dryer) of mats of foamed and non-foamed apple juice. The energy consumption for drying foamed apple juice was estimated to be... 

Dehydration is performed in a conveyor or tube dryer at 55-60 °C to a residual moisture content of 4-8%. Liquid or paste forms, such as tomato or potato mash, are dried in a spray or drum dryer or, in the case of some special products, in a fluidized bed dryer. Dehydration by freeze-drying provides high quality products (good shape retention) with a spongy and porous structure that is readily rehydrated. Some vegetables used in soup powders, e. g., peas and cauliflower, are prepared in this way. For production of dehydrated potato products (Fig. 17.4), tubers are peeled, cleaned, sliced into strings or chips or diced and, after... 

The heat setting of the tow is performed in a duct or in a perforated drum dryer fiber bonding shrinkage after this process should be less than 1%. 

The material comes off as flakes 1-3 mm or less thick. They are broken up to standard size of about g in. square. That process makes fines that are recycled to the dryer feed. Drying times fall in the range of 3-12 sec. Many laboratory investigations have been made of drying rates and heat transfer coefficients, but it appears that the only satisfactory basis for sizing plant equipment is pilot plant data obtained with a drum of a foot or more in diameter. Usually plant performance is superior to that of pilot plant units because of steadier long time operation. 

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