Page 286 - Chemical Process Equipment - Selection and Design

9.6 ROTARY CYLINDRICAL DRYERS 253

TABLE 8.9. Performance of Through-Circulation Belt Conveyor Dryers [See Figs. 9.8(cI-(e)l
(a) Data of A.P.V.-Mitchell (Dryers) Ltd.
Nickel Metallic
Fertilizers Bentonite Pigment Hydroxide Stearate
Effective dryer length 42ft 6 in. 60ftOin. 24ftOin. 24ftOin. 41ft3in.
Effectbe band width 8ft6in. 8ft6in. 4ROin. 4ftOin. 6ftOin.
Capacity (Ib product/hr) 2290 8512 100 125 125
Method of feeding oscillator oscillator
Feedstock preforming} extruder extruder extruder
Initial moisture (96 w/w basis) 45.0 30 58.9 75 75
Final moisture (% w/w basis) 2.0 10.0 0.2 0.5 0.2
Drying time (min) 16 14 60 70 60
7.0
Drying rate (Ib evaporated/ft*/hr) - 6.5 2.0 7.5 1.5
-
Air temperature range (“F) - - -
-
-
Superficial air velocity (ftlmin) 200 200 180 180 125
-
Heat consumption (Btu/lb evaporated) - -
Method of heating direct oil direct oil steam steam steam
Fan installed HP 35 50 14 14 28
- ~~
(Williams-Gardner, 1971).
(b) Data of Kraurs-Maff~i-lmprrial GmbH
Altirninium Polyacrylic Calcium Titanium
Hydrate Nitrile Sulfur Carbonate Dioxide
Effective dryer length 32 ft 9 in. 43ftOin. 28ft0 in. 50 ft 0 in. 108 ft 0 in.
Effective band width 6ft6in. 6ft6in. 6ft6in. 6ft3in. 9ft6in.
Capacity (Ib productlhr) 61 5 2070 660 1800 6000
Feedstock preforming 1
Method of feeding grooved extruder extruder extruder extruder
drum
Initial moisture (% wlw basis) 38.0 55.0 45.0 60.0 50.0
Final moisture (% w/w basis) 0.2 1 .o 1 .o 0.5 0.5
Drying time (min) 26 52 110 40 45
Drying rate ilb evaporated/hr/ft*) 2.88 3.37 3.57 5.73 6.0
Air temperature range (OF) 233 186/130 194/230 320 3141392
Superficial air velocity (ftlrnin) 140 1001216 140 160 150
Heat conlsumption (Ib steam/lb
evaporated) 1.7-1.8 1.8-1.9 1.8-1.9 1.7-1.8 1.8- 1.9
Method of heating 50 Iblin.’ 25 Ib/in.’ 90 Ib/in? 160 Ib/in.’ 260 Iblin.’
steam steam steam steam steam
Fan installed hD (awrox.) 25 65 20 35 80
(Williams-Gardner, 1971 I.
(c) Data oif Piactor and Schwartz Inc.
Inorganic Charcoal inorganic
Kind of Material Pigment Cornstarch Fiber Staple Briquettes Gelatin Chemical
Capacity (kg dry product/hr) 712 4536 1724 5443 295 862
Stage A Stage B
Approximate dryer area (m’) 22.11 66.42 57.04 35.12 52.02 104.05 30.19
Depth of loading (cm) 3 4 - - 16 5 4
Air temperature 4%) 120 11 5-140 130-100 100 135-120 32-52 121-82
Loading (kg product/m2) 18.8 27.3 3.5 3.3 182.0 9.1 33
Type of conveyor (mm) 1.59 by 6.35 1.19 by4.76 2.57-diameter 8.5 4 .23 x 4.23 mesh 1.59 x 6.35 slot
slots slots holes, perforated x 8.5 mesh screen
plate screen
Preforming method or feed rolling filtered and fiber feed pressed extrusion rolling
extruder scored extruder
Type and si;x of preformed 6.35-diameter scored filter cut fiber 64X 51 x 25 2-diameter 6.35-diameter
particle (mm) extrusions cake extrusions extrusions
Initial moisture content (% 120 85.2 110 37.3 300 111.2
bone-dry basis)
Final moisture content (% bone- 0.5 13.6 9 5.3 11.1 1 .o
dry basis)
Drying time (min) 35 24 11 105 192 70
Drying rate [kg water 38.39 42.97 17.09 22.95 9.91 31.25
evaporated/(hr m2)1
Air velocity (superficialNm/sec) 1.27 1.12 0.66 1.12 1.27 1.27
Heat sourca per kg water gas steam steam waste heat steam gas
evaporated [steam kglkg gas 0.7 1 2.0 1.73 2.83 0.13
(m”1kg)l
Installed power (kW) 29.8 119.3 194.0 82.06 179.0 41.03
(Perws Chemicel Engineers Handbook, McGraw-Hill, New York, 1984).