Page 294 - Chemical Process Equipment - Selection and Design

(e) Steam Tube Dryers

Class 1 Class 2 Class 3

Class of materials high moisture organic, distillers' pigment filter cakes, blanc fixe, finely divided inorganic solids, water-
grains, brewers' grains, citrus barium carbonate, precipitated ground mica, water-ground silica, flo-
Pulp chalk tation concentrates
Descriation of class wet feed is granular and damp but wet feed is pasty, muddy, or wet feed is crumbly and friable, product
not sticky or muddy and dries to sloppy, product is mostly hard is powder with very few lumps
granular meal pellets
Normal moisture content of wet 233 100 54
feed (% dry basis)
& Normal moisture content of product 11 0.15 0.5
(D (% dry basis)
Normal temperature of wet feed (K) 310-320 280-290 280-290
Normal temperature of product (K) 350-355 380-41 0 365-375
Evaporation per product (kg) 2 1 0.53
Heat load per Ib product (kJ) 2250 1190 625
Steam pressure normally used (kPa 860 860 860
gauge)
Heating surface required per kg 0.34 0.4 0.072
product (m2)
Steam consumption per kg product 3.33 1.72 0.85
(kg)

(Chemical Engineers' Handbook, 1984).