Page 363 - Chemical Process Equipment - Selection and Design

326 SOLID-LIQUID SEPARATION

Air connection
Confinuous rotary filter

Dry
vacuum
Air
Wosh

v
Pump
seal

(a)

Cake saturated
~
with wash liquor

Cake saturatedh AStlrrJng
with filtrate Cake forming device

(b) (C)
Figure 11.12. Continuous rotary drum filters. (a) Flowsketch of continuous vacuum filtration with a rotary drum filter. The solids
are taken away with a screw or belt conveyor (McCube and Smith, Unit Operations of Chemical Engineering, McGruw-Hill, New
York, 1956). (b) Cross section of a dip-type rotary drum filter showing the sequence of cake formation, washing, dewatering and
cake removal; units also are made with top feed (Oliver United Filters). (c) Cross section of a rotary drum filter with internal
filtering surface, suited particularly to free settling slurries (Oliver United Filters). (d) Rotary filter with a filtering belt that is
discharged and cleaned away from the drum; in the similarly functioning string discharge filters, the filtering cloth remains on the
drum but the string assembly follows the path shown here for the belt. (e) Double drum filter, particularly suited to rapidly
settling slurries, and may be adapted to cake washing which is not shown in this unit (System Gerlach, Nordhausen, E.
Germany). (f) Vacuum disk filter , the main kind in use when cake washing is not required (Dorr-Oliver Znc.).