Rotatory drum vacuum filter

separation of solid by cake formation through the vacuum.

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.

3. 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.

4. 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.

5. 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.

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

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

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

9. 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.

10. 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.

11. 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.

12. Roll Discharge It is modified form of scraper discharge. S craper 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.

13. 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