Page 397 - Chemical Process Equipment - Selection and Design

360 DISINTEGRATION, AGGLOMERATION, AND SIZE SEPARATION OF PARTICULATE SOLIDS

Blunger dimensions

Length (m) 4.5
Width (m) 1-4
Height (m) 1-07
Screw diameter (m) 0.8
Pitch (m) 1.7
Shaft speed (rpm) 55
Capacity (kg s-*) 23-25
Installed power (kW) 104

(a)

APPROXIMATE SIZE
MATERIAL BULK CAPACITY (WIDTH X LENGTH) SPEED DRIVE
MODEL DENSITY LBIFT~ (TONS/H R) (FT) (RPW (H P)
~
A 25 8 2x8 56 15
50 15 2X 8 56 20
I5 22 2X 8 56 25
100 30 2x8 56 30
25 30 4x8 56 30
50 60 4x8 56 50
75 90 4x8 56 15
100 120 4x8 56 100
25 30 4x 12 56 50
50 60 4x 12 56 100
15 90 4x 12 56 150
100 120 4x 12 56 200
125 180 4x 12 56 300

(b)
Figure 12.12. Paddle blending granulator and typical performance. (a) Sketch of a double paddle trough granulator (Sherrington
and Oliver, 1984). (b) Performance in granulation of fertilizers (Feeco International).

abrasive materials. Economically feasible power requirements Nostrand Reinhold, New York, 1982); such equipment is applicable
correspond to the range of 100-200 Ib/HP hr. The main types of to other situations.
machines are illustrated in Figures 12.10(e) and 12.15. Ring pellet mills consist of a power driven rotating ring with
Screw extruders usually are built with a single screw as shown, radial holes, friction driven rolls to force the material through the
but may have as many as four screws and the die may have multiple holes and knives to cut the extrudate to desired lengths. The feed is
holes of various cross sections. An Sin. dia screw can have a charged with screw feeders into the spaces between the rolls and the
capacity of 2000 Ib/hr of molten plastics. Tubing can be extruded at feed distributor flights. Hole diameters range from 1.6 to 32mm.
150-300 ft/min. To make pellets, the extrudate goes to cutting The force of compaction is due to flow friction through the die.
machines in which parts as small as washers can be made at rates as Differing flow and compression characteristics are accommodated
high as 8000/min. The extrusion of plastics is described at length by by varying the thickness of the ring. A production rate of
Schwartz and Goodman (Plastics Materials and Processes, Van 200 lb/HP hr has been quoted for a normal material through 0.25 in.