Page 371 - Chemical Process Equipment - Selection and Design

334 SOLID-LIQUID SEPARATION
TABLE Il.l%(continued)
(b) Criteria for Selection of Sedimentation Centrifuges
Parameter Tubular Bowl Skimmer Pipe Disc Scroll

Solids concentration. vol./vol. <I % up to about 40% up to about 20% any as long as it remains
pumpable
Particle size range processable for 4-50 pm 10 ~m-6 mm 1-400pn 5 pm-6 mm
density difference under 1 g/cc and
liquor viscosity 1 CP
Settling time of 1 litre under 1 g Few hours to infinity 4 hr to days several hours 4-1 hr
Settling time of 50 cc at 2000 g 5-15 min 1-5 min 5-10 min 1-5 min
Approximation maximum throughput 5000 litre/hr 15,000 litre/hr 100,000 litre/hr 70,000 litre/hr
for largest machine
Approximate nominal throughput for 1250 litre/hr 12,000 litre/hr 40,000 litre/hr 30,000 litre/hr
largest machine
Nature of bottle spun solids Can be any consistency Must be fluid to Must not be too cohesive Preferably compact and
Pasty cohesive
Batch or continuous Batch Semi Semi or continuous Continuous
Floc applicable Possibly but not usual Yes No Yes
g levels used Up to 18,000. 60,000 Up to 1600 4500-12,000 500-4000
Laboratory model
Maximum sigma value x 107cm2 5 4 10 14
(F.A. Records).

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