Page 297 - Chemical Process Equipment - Selection and Design

9.8. PNEUMATIC CONVEYING DRYERS 261

cwforrnance Data of Drum Dryers
(a) Drum Dryers
Yeast Stone Starch Zirconium Brewers Clay
Cream Slop Solutions Glaze Silicate Yeast Slip
Feed solids (% by weight) 16 40 36 64 70 25 75
Product moisture (% w/w basis) 5.7 0.2 5 0.2 0.2 5 9
Capacity (Ib proal./hrl 168 420 300-400 225 1120 146 4000
Dryer type (a) single, (b) Win, jc) double (a) (a) (a) (a) (a) (a) (a)
Drum
diameter 4ftOin. 2ft6in. 48 in. 18 in. 36 in. 28 in. 48 in.
length 10 ft 0 in. 5ftOin. 120 in. 36 in. 72 in. 60 in. 120 in.
Type of feed method top roller dip top roller side dip center nip side
Steam pressure Ilb/inz gauge) 80 60 80 - 80 40 40
Atmospheric or vacuum atmos. atrnos. atmos. atmos. atmos. atmos. atmos.
Steam consumption Ilb/lb evaporated) - 1.3 1.3 - - 1.35
Average effective area (%I - - 86 - - - 65
Evaporation/ftz/tir 6.5 4 5 9 8.4 6 8.4
(Courtesy A.1P.V. Mitchell Qryers, Ltd.; Williams- .Gardner, 1971 ).

Eb) Drum Rryers in the Size Range 0.4 X 0.4-0.8 X 2.25 ma

Type of Dryer H20 Output Evaporation
and Feed Drum Steam Solids in of Dried Rate of
Size by Lettelr, Speed Press Type of Physical Form in Feed Product Product Water
A. B, or C (revlmin) bar, g) Material of Feed (%I (%I (g/sec m2) (g/sec m2)
inorganic salts
Single (dip) 4.4 3.5b alk. carbs - 50 8-12 5.5 4.9
Single (spiash) 1 3.0 Mg(OH)z thick slurry 35 0.5 1.9 1.5
Twin (splash) A 3 3.0 Fe(OH), thin slurry 22 3.0 4.3 1.3
Double 3-8 5.0 Na Acetate solution 20 0.4-1 0 2.0-7.0 8-24
Double and twin 7-9 2-3 Na,SO, solution 24 0.1 5-5.5 4.7-6.1 11-12
Double and twin 5-9 4-6 NaZHPO4 solution 44 0.8-0.9 8.2-1 1.1 9-14
Twin (dip) A 5 5.5 organic salts solution 27 2.8 1.9 5.2
Twin A 3 5.5 organic salts solution 33 13.0 1.4 2.6
Twin B 2c 3.5 organic salts solution 20 1 .o 1 .O 3.8
Twin C 5 5.5 organic salts solution 39 0.4 3.9 6.1
Twin C 5; 5.5 organic salts solution 42 1 .o 2.1 4.6
Twin C 6 5.5 organic salts solution 35 5.0 4.1 7.2
Twin (splash) A 3-5 5.0 organic salts thin slurry 20 1.7-3.1 1 .o-1.9 3.7-7.3
Double A 5; 6.0 organic salts solution 11 - 1.1 9
Double B 62 5-6 organic salts solution 40 3 3.4 4.9
Twin (dip) A 5 5.5 thin slurry 30 1.2 2.4 5.5
Twin A 5 5.0 organic viscous soh. 28 10.5 1.9 4.2
Double 2 3.0 compounds viscous soh - 6.0 0.7 -
Double 44 3.5 thin slurry 25 1 .0 0.4-1.9 3.5-5.0
Twin (dip) 5 5.0 organic (a) solution 25 0.5 0.3 0.8
Twin 10 5.5 compounds of (b) thick slurry 30 2.5 2.0 4.6
Twin 10 5.5 low surface (c) thick slurry 35 - 3.1 -
tension
Double 11 5.5 similar (b) thin paste 46 - 6.4 7.3
letters
Double 12 5.5 for same (c) thick paste 58 - 6.0 4.3
Double 11 5.5 compound (a) solution 20 0.5 0.24 1 .O
"Dryer dia and width (m): (A) 0.457 x 0.4157; (B) 0.71 x 1.52; (C) 0.91 x 2.54.
Plus external hot air flow.
cStainless sfeel drum.
(Nonhebel and Moss, 1971).