Page 281 - Chemical Process Equipment - Selection and Design

TABLE 9.6. Performance Data of Batch Tray and Tray-Truck Dryers
(a) Cross-Flow Operation
Coated As irin Base Filter Filter Filter
Tablets PTFE granules Stearates Chalk Cake Cake Cake

Capacity, wet charge (Ib) 120 80 56 20,000 1800 3000 2800 4300
Number of trays 40 20 20 320 72 80 80 80
Tray area (ft’) 140 70 70 4800 1130 280 280 280
Depth of loading (in.) 0.5 1 .o 0.5 2.0 2.0 1 .o 1 .o 1.5
Initial moisture (% w/w basis) 25 25-30 15 71 46 70 70 80
Final moisture (% w/w basis) nil 0.4 0.5 0.5 2.0 1 .o 1 .o 0.25
Maximum air temperature (OF) 113 284 122 200 180 300 200 200
Loading (lb/ft2) 0.9 1.2 0.4 0.9 0.91 3.25 3.04 11.7
Drying time (hr) 12 5.5 14 24 4.5 22 45 12
Overall drying rate (Ib/hr) 2.6 5.3 0.84 62.5 185 96.6 43.2 90
Evaporative rate (Ib/hr/ftZ) 0.0186 0.05 0.008 0.013 0.327 0.341 0.184 0.317
Total installed HP 1 1 1 45 6 4 2 2
~ ~ ~~ ~ ~ ~~~~~
(Williams-Gardner, 1971, P. 75, Table 12: first three columns courtesy Calmic Engineering Co.; last five columns courtesy A.P.V.-Mitchell
(Dryers) Ltd.)
(b) Vacuum Dryers with Steam Heated Shelves
~~~
Soluble Paint Ferrous Ferrous Lithium Tungsten Stabilized
Aspirin Pigment Glutinate Succinate Hydroxide Alloy Diazamin
Capacity, wet product (Ib/h) 44 30.5 41.6 52.5 36.8 12.8 4.6
Tray area (ft‘) 108 108 108 108 54 21 5 172
Depth of loading (in.) 1 2 0.5 1 1 0.5 0.75
Initial moisture (% w/w basis) 72.4 49.3 25 37.4 59 1.6 22.2
Final moisture (% w/w basis) 1.25 0.75 0.5 18.8 0.9 nil 0.5
Max temp (“F) 104 158 203 203 122 239 95
Loading [Ib charge (wet) ft’] 6.1 102 2.3 1.94 3.08 7.1 6 1.22
Drying time (hr) 15 36 6 4 4.5 12 48
Overall drying rate (Ib moisture evaporated/ft2/hr) 0.293 0.14 0.11 0.1 1 0.034 0.013 0.0058
Total installed HP 6 6 6 6 3 2 5
Vacuum (in. Hs) 29.5 28 27 27 27 29 22-23
(Williams-Gardner, 1971, p. 88, Table 15: courtesy Calmic Engineering Co.).
(c) Vacuum Dryers with Steam-Heated Shelves

Calcium Calcium
Material Sulfur Black Carbonate Phosphate
~ ~~ ~
Loading (kg dry material/m’) 25 17 33
Steam pressure (kPa gauge) 41 0 410 205
Vacuum (mm Hg) 685-710 685-71 0 685-71 0
Initial moisture content (%,wet basis) 50 50.3 30.6
Final moisture content (%,wet basis) 1 1.15 4.3
Drying time (hr) 8 7 6
Evaporation rates (kg/sec m2) 8.9 x 7.9 x IO-^ 6.6 X
(Chemical Engineers’ Handbook, McGraw-Hill, New York, 1984, p. 20.23, Table 20.8).
(d) Through Circulation Dryers
~~
Granular Vegetable
Kind of Material Polymer Vegetable Seeds
Capacity (kg product/hr) 122 42.5 27.7
Number of trays 16 24 24
Tray spacing (cm) 43 43 43
Tray size (cm) 91.4~ 104 91.4~ 104 85 x 98
Depth of loading (cm) 7.0 6 4
Physical form of product crumbs 0.6-cm diced washed
cubes seeds
Initial moisture content (%, dry basis) 11.1 669.0 100.0
Final moisture content (%, dry basis) 0.1 5.0 9.9
Air temperature (“C) 88 77 dry-bulb 36
Air velocity, superficial (m/sec) 1 .o 0.6-1 .O 1 .o
Tray loading (kg product/m2) 16.1 5.2 6.7
Drying time (hr) 2.0 8.5 5.5
Overall drying rate (kg water evaporated/hr rn’) 0.89 11.86 1.14
Steam consumption (kg/kg water evaporated) 4.0 2.42 6.8
Installed power (kW) 7.5 19 19
(Proctor and Schwartz Co.).
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