The document summarizes the key components and functioning of a rotatory drum vacuum filter. It consists of a sheet metal drum divided into sections covered with a filter cloth. Liquor is sucked through the filter cloth onto the rotating drum to deposit a cake of solids. As the drum rotates, the cake moves through different zones - first forming in the filtration zone, then being washed and dried before the cake is removed in the removal zone by a doctor knife. Various methods are used to discharge the cake, including scrapers, belts, pre-coat, rolls or strings depending on the cake properties. It is widely used in industrial processes that require continuous large-volume solid-liquid separation.

1. Rotatory Drum Vacuum Filter
Presented by:
Qaisar Yaqoob
2014-BT-CHEM- 19
Presented to:
Mr. Haris Mahmood Khan
Department of Chemical Engineering and Technology
UNIVERSITY OF ENGINEERING AND TECHNOLOGY LAHORE, K.S.K
CAMPUS.

2. Introduction
 The most common type of continuous vacuum filter.
 The rotary drum filter in which liquor is sucked through a moving
septum to deposit a cake of solids.
Cake is moved out of the filtering zone, washed, sucked dry and
dislodged from the septum.

4. Construction
It is consisting on a sheet metal drum.
A vacuum system is also attached.
The surface of the drum is the divided into different section by stripes.
Filter medium is hold by metal strips on drum and covered by filter
cloth.
In each section there are many pipes which open inside the cover
plates.
To remove the cake “Doctor knife” is provided.

7. Working
Before filtration rotary drum filter is dip in tank of filter aid for pre-
coating (e.g. diatomaceous earth, perlite or purified wood cellulose).
Drum is rotated in slurry tank at a speed of 1 to 2 rpm. 1/3 of drum is
dip in slurry tank and vacuum is applied.
Cake formation.
As, the panel leave the cake formation zone it enters to washing zone.
As, the panel leave the cake formation zone it enters to washing zone.
Cake removed in cake removal zone.

9. Industrial Application
These filter are developed to overcome large problem of filter press
and leaf filter. It is very versatile filter.
It is used generally for those operation in which the volume is very
large.
It is used where colloidal particles.
It is used for production of wallboard from gypsum.

10. Limitations
It cannot be used for mixture of colloidal and coarse particles.
It must be used continuously.

11. Filter Auxiliaries
Rotary drum filter
Vacuum arrangement
Filtrate Pump
Filtrate receiver
Filtrate separate

12. Cake Discharge Methods
The five basic cake discharge types are given bellow,
Scraper discharge
Belt discharge
Pre-coat discharge
Roll discharge
String discharge

13. Scraper Discharge
In this method scraper is used to remove cake from septum.
But filter cloth selection must provide good wear.
Scraper has high resistance against solid blinding.
It’s used for wide and hard layer of cake.
It has simple design.

15. Belt Discharge
In this method endless belt is used to discharge cake.
Ensure that a septum (filter cloth) is selected which provides a smooth
surface for good release.
Cake is removed by high pressure water which is spray on moving
belt.
Best for slurries with moderate solid content.
In this design cloth continuously cleaned.

17. Pre-coat Discharge
In this filtration operations filter aid is added to slurry.
it is well suited for those slurries which having very low
concentration.
In this design septum is disposable and renewable.
Typical filter medium is diatomaceous earth or perlite.
Cake is removed by advanced knife.

19. Roll Discharge
It is modified form of scraper discharge.
Scraper is adjusted on revolving roll.
Roll speed must be match to rpm of drum.
Used for sticky and mud like cake.
It having low filtration rate.

21. String Discharge
String having high strength is used to discharge cake
it requires well maintained track and good alignment
It is used for slurries having high content of solids
Solids must be fibrous, stringy or pulpy material