Rotary Drum Filter

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DRUM FILTER Principle: Rotary drum flter unctions on the principle o fltering the slurry through siee!li"e mechanism on a rotating drum surace# under the conditions o acuum$ In addition# compression# drying %using hot air& and remoing the flter ca"e %using a "nie& are possi'le$ Construction: The construction construction o a rotary rotary drum flter flter is sho(n sho(n in the ollo(ing fgure$ It consists o a metal cylinder mounted hori)ontally$ The drum may 'e up to * meters in diameter and *$+ meters in length# and gies a surace area o ,- meter s.uare$  The cured surace is a perorated perorated plate# (hich (hich supports supports a flter cloth$ The drum is radially partitioned diiding the annular space into separate compartments$ Each o it is connected 'y an internal pipe to the center o the drum through a rotating ale$ Working: The drum is rotated at a speed less than one reolution per minute$ The drum /ust enters the slurry in the trough$

0s it dips# acuum is applied in this segment so that the solid is 'uild up on the surace$ The li.uid passes through the flter cloth into an internal pipe and ale$ Finally the fltrate reaches the collecting tan"$  0s the drum leaes the slurry section# it enters the drainage )one$ 1ere e2cess o the li.uid is dra(n inside$ 3pecial ca"e compression roller may he included at this stage# so that the ca"e is consolidated 'y the compression o the ca"e$ This improes the e4ciency o (ashing and drying process$ •

5acuum is applied to carry the slurry along (ith the drum

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• • •

Drainage )one 6ater (ashing arrangement Drying )one ! dry air supply 7a"e remoal )one

0s the drum leaes the drainage )one# it enters the (ater (ash section$ 6ater is sprayed on the ca"e$ 0 separate system o acuum is applied on the panel in order to suc" the (ash li.uid and air through the ca"e o solids$ 6ash li.uid is dra(n through the flter into a separate collecting tan"$

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 Then the ca"e enters the drying )one# (here hot air is 'lo(n on the ca"e$ The ca"e may hae the moisture content less than one percent$ Finally the ca"e is remoed using a doctor "nie and discharged$ 0ll these steps are completed in one rotation o the drum$ 8o( the drum is ready to receie a resh lot o slurry$

Uses: Drum flter is used or continuous operation and is utili)ed to flter slurries containing high proportion o solids up to 9+ to *percent$ In the production o penicillin# the e2tract is separated rom mycelium %cell mass& 'y drum flters$ These are used or collecting calcium car'onate# starch and magnesium car'onate$

Advantages:

9$ 7a"e is remoed simultaneously during operation$ Thereore# it is suita'le or use (ith concentrated slurries$ ,$ The la'our costs are ery lo( on account o automatic and continuous operation o the rotary flter$ *$ The flter has large surace area$ :$ The speed o rotation can 'e aried and the ca"e thic"ness can 'e controlled$ For e2ample# i the solids orm an impenetra'le ca"e# the thic"ness may 'e limited to less than + millimeters$ ;n the other hand# i the solids are coarse and orm a porous ca"e# the thic"ness o 9-- millimeters or more# can 'e o'tained$ Disadvantages:

9$ Rotary drum flter is e2pensie e.uipment (ith comple2 unctioning$ It contains moing parts and also re.uires a

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num'er o accessories such as acuum pumps# acuum receiers# traps etc$ ,$ The ca"e tends to crac" due to the air dra(n through 'y the acuum system$ This ma"es (ashing and drying processes ine4cient$ *$  The rotary flter is suita'le only or straightor(ard slurries$ It is less satisactory# i the solids orm an impermea'le ca"e or it is di4cult to remoe the ca"e ade.uately$