Rotatory Drum Vacuum Filter

Presented by:Qaisar Yaqoob2014-BT-CHEM- 19

Presented to:Mr. Haris Mahmood Khan

Department of Chemical Engineering and TechnologyUNIVERSITY OF ENGINEERING AND TECHNOLOGY LAHORE, K.S.K

CAMPUS.

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.

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.

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.

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.

Limitations

It cannot be used for mixture of colloidal and coarse particles.

It must be used continuously.

Filter AuxiliariesRotary drum filter

Vacuum arrangement

Filtrate Pump

Filtrate receiver

Filtrate separate

Cake Discharge Methods

The five basic cake discharge types are given bellow,

Scraper dischargeBelt dischargePre-coat discharge Roll dischargeString discharge

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.

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.

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.

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.

String Discharge

String having high strength is used to discharge cakeit requires well maintained track and good alignmentIt is used for slurries having high content of solidsSolids must be fibrous, stringy or pulpy material