Drum dryer

Drum dryers are shown in Fig. 3.15c. his consists of a heated metal roll. As the roll rotates, a layer of liquid or slurry is dried. The final dry solid is scraped off the roll. The product comes ofiF in flaked form. Drum dryers are suitable for handling slurries or pastes of solids in fine suspension and are limited to low and moderate throughput. 

Cylinder Heat-Transfer Units Sometimes called can dryers or drying rolls, these devices are differentiated from drum diyers in that they are used for solids in flexible continuous-sheet form, whereas drum dryers are used for liquid or paste forms. The construction of the individual cyhnders, or drums, is similar in most respec ts to that of drum diyers. Special designs are used to obtain uniform distribution of steam within large drums when uniform heating across the drum surface is critical. 

Drum dryers. These moy be heated by steom or hot water... 

Ammonium sulfate is produced as a caprolactam by-product from the petrochemical industry, as a coke by-product, and synthetically through reaction of ammonia with sulfuric acid. Only the third process is covered in our discussion. The reaction between anunonia and sulfuric acid produces an ammonium sulfate solution that is continuously circulated through an evaporator to thicken the solution and to produce ammonium sulfate crystals. The crystals are separated from the liquor in a centrifuge, and the liquor is returned to the evaporator. The crystals are fed either to a fluidized bed or to a rotary drum dryer and are screened before bagging or bulk loading. 

For drying small fabrieated parts, a helieal drum dryer is often employed. This maehine eonsists of a perforated, rotating stainless steel drum eonveyor that employs a high veloeity airknife system to provide eontinuous throughput and 100 % drying of small, fabrieated parts. 

Drum dryers for pastes and slurries operate with contact times of 3-12 sec, produce flakes 1-3 mm thick with evaporation rates of 15-30kg/m2hr. Diameters are 1.5-5.0ft the rotation rate is 2-10 rpm. The greatest evaporative capacity is of the order of 3000 Ib/hr in commercial units. 

Drying the separated, sulfonated asphalt by passing it through a drum dryer... 

Drum dryers are used for liquid and dilute slurry feeds. They are an alternative choice to spray dryers when the material to be dried will form a film on a heated surface, and is not heat sensitive. 

Double-cell system, in soil and ground water treatment, 25 835 Double crucible technique, 11 135-136 Double-deck kiln, 15 530 Double-drum dryers, 9 134 Double-drum separator, 15 446 Double-effect distillation, 10 153 Double end point titration method,... 

Finasteride, 2 816-817 Fin-drum dryer, 9 134 Fine art examination/conservation, 77 397-423... 

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... 

Figure 16.17. Methods of feeding drum dryers, (a) Single drum, dip-feed, (b) Single drum, pan-feed, (c) Single drum, splash-feed, (d) Double drum, dip-feed. (e) Double drum, top-feed... 

Grains. Grains are usually prereduced powders. The quantities of sodium sulfide, hydrosulfide, and mineral salts are adjusted to give a grainy product when the paste slurry is dried on a steam-heated drum dryer. Grains offer the advantage of not being dusty. 

The standard conventional finishing process has been modified to suit the purposes for different fabrics and garments. For example, tubular knits are frequently handled using specialized equipment to control tension and to get adequate padding. Some tubular knits are subjected to wet-on-wet padding, dried and cured in large drum dryers, and steam-treated to achieve a relaxed and nondistorted knit. 

FIG 8 - DOUBLE-DRUM DRYER WITH PIPE FEED... 

FIG 9 - TWIN-DRUM DRYER WITH SPLASH FEED... 

VACUUM SINGLE-DRUM DRYER SHOWING PATENTED SPRAY FILM FEED... 

Sodium and Potassium Benzoate. These salts are available in grades meeting the specifications of the National Formulary (18) and the Food Chemicals Codex (19) (Table 7). Sodium benzoate [552-52-1] is produced by the neutralization of benzoic acid with caustic soda and/or soda ash. The resulting solution is then treated to remove trace impurities as well as color bodies and then dried in steam heated double drum dryers. The product removed from the dryers is light and fluffy and in order to reduce shipping and storage space the sodium benzoate is normally compacted. It is then milled and classified into various product forms, the names of which often bear little relationship to the actual form of the product. 

Drum dryers potatoes, cereals, buttermilk, skim milk, dextrins, yeasts, instant oat meal, polyacylamides, sodium benzoate, propionates, acetates, phosphates, chelates, aluminum oxide, m-disulfuric acid, barium sulfate, calcium acetate-arsenate-carbonate-hydrate-phosphate, caustic, ferrous sulfate, glue, lead arsenate, sodium benzene sulfonate, and sodium chloride... 

Vacuum drum dryers syrups, malted milk, skim milk, coffee, malt extract, and glue... 

A safe estimate of power requirement for double drum dryers is approx 0.67 HP/(rpm)(100 sqft of surface). Maintenance can be as high as 10%/yr of the installed cost. Knives last from 1 to 6 months depending on abrasiveness of the slurry. Competitors for drum dryers are solid belt conveyors that can can handle greater... 

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