Principle, construction, working, advantage and disadvantages of semicontinuous centrifuge

1. SEMI CONTINUOUS CENTRIFUGE

2. SEMI CONTINUOUS CENTRIFUGE
SHORT CYCLE AUTOMATIC BATCH CENTRIFUGE
Principle:-
❖Filtration centrifuge
❖The bowl contains a perforated side wall
❖The separation is through a perforated wall
based on the difference in densities of solid
and liquid phases

3. SEMI CONTINUOUS CENTRIFUGE
❖During centrifugation, the liquid phase passes
through the perforated wall, while solid phase
retains in the bowl
❖The solid is washed and removed by cutting
the sediment using a blade

4. SEMI CONTINUOUS CENTRIFUGE
Construction:-
❖It consists of a vertical perforated basket
❖The basket is supported from a horizontal
shaft driven by a motor
❖Slurry inlet and wash water pipes are
introduced from the side of the basket

5. SEMI CONTINUOUS CENTRIFUGE
❖The thickness of the feed depends on the
feeler which rides over the feed
❖The layer of the cake is removed by a chute
fitted with knife

6. SEMI CONTINUOUS CENTRIFUGE
❖The knife cuts down the cake within the basket
❖The knife-chute assembly is raised with the
help of a hydraulic apparatus

7. SEMI CONTINUOUS CENTRIFUGE
Working:-
❖The basket is rotated horizontally with a motor
❖The slurry is introduced through the pipe
❖During centrifugation slurry passes through
the perforated wall

8. SEMI CONTINUOUS CENTRIFUGE
❖The solids retained in the basket while filtrate
leaves the basket
❖Filtrate collected at outlet
❖The cake is washed with water. The washed
water escape from the basket through the
filtrate outlet

9. SEMI CONTINUOUS CENTRIFUGE
❖After achieving the desired thickness of the
cake the slurry inlet is stopped by a feeler-
diaphragm –valve assembly
❖The basket rotates predetermined time and
then the cake is washed with water again
rotated for another predetermined time

10. SEMI CONTINUOUS CENTRIFUGE
❖The hydraulic cylinder is actuated which lifts
the knife along with the discharge chute
❖The knife does not cut the cake completely but
leaves a layer of crystals that act as a filter
medium for further separation in the next cycle
❖The cake is collected through the chute

11. SEMI CONTINUOUS CENTRIFUGE
Advantage:-
❖Solids can be drained fast from the bowl
Disadvantages:-
❖Moving parts involved so construction and
functioning is complicated
❖During discharge breakage of cake occurs

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