http://www.komline.com/
CESCO offers a few different vacuum filter designs. In general, vacuum filters are suitable for use with fast-filtering materials. In addition, with the use of precoat filter aid, the precoat rotary drum vacuum filter is often used for sticky/oily hard to filter waste streams where it is important to have a fresh filter surface for each drum rotation.
Rotary Drum Vacuum Filter: http://www.komline.com/docs/rotary_drum_vacuum_filter.html
A rotary drum vacuum filter (RDVF) is a continuous filter. The solids to be collected, whether in a pulp or slurry, are separated by a porous filter cloth or other media rotated through the pulp or slurry, with vacuum applied to the inner surface to cause the solids to accumulate on the surface as a cake or layer, through which the liquid is drawn.
The process cycle of the RDVF is continuous. Each revolution consists of:
1. Cake Formation - during the time period the drum is submerged in the vat
2. Cake Filtration - during the time period right after the drum exits the liquid
3. Cake Washing (if required) - typically near the top of the drum
4. Cake Dewatering/Drying - right after cake filtration (or washing, if required)
5. Cake Discharge - right before the drum enters the liquid again
As the drum rotates - partially submerged in the slurry - vacuum draws the liquid through the filter medium (cloth) on the drum surface which retains the solids. The vacuum pulls air (or gas) through the cake and continues to remove liquid as the drum rotates. If required, the cake can be washed prior to final drying...and discharge. The filtrate and air flow through the internal filtrate pipes, through the rotary valve and into a vacuum receiver where the liquid is separated from the gas stream. Vacuum is normally developed by a liquid ring vacuum pump or barometric leg. Multiple receivers connected to the filter valve allow for the separation of mother liquor from the wash liquor, and vacuum levels can be varied at the cake forming and washing/drying zones. The units also are available as vapor retaining or vapor tight unit. Here is a vapor tight unit:
There are various designs available, and the selection depends on the nature of the process, and the cake characteristics upon discharge. Options include:
Type of Discharge
Flexible Filter Belt Discharge:
Where filter medium washing is required to prevent blinding.
For the discharge of thin cakes.
For dry cake discharge or sluice (wet) cake discharge.
Typical applications -
Corn Gluten
Starch
Pharmaceuticals
Fermentation Broths
Pigments
Organic/Inorganic Chemicals
Water Softening Sludge
Steel Mill Waste
Hydroxide Sludge
Industrial Wastewater
Precoat Discharge:
For slimy, sticky, oily and blinding solids.
For clear filtrates.
For filtering dilute slurries with varying feed concentrations.
For the discharge of very thin filter cakes.
Typical applications:
Corn Syrup Clarification
Fruit Juices and Wines
Pharmaceuticals
Fermentation Broths
Food Processing Wastes
Hydroxide Sludge
Slop Oil
Flexographic Ink Wastes
Industrial Wastewater
Scraper Discharge:
For fast filtering materials.
For filtering/dewatering granular or crystalline solids.
For discharging cakes in excess of 1/4" thick.
For non-blinding cakes where cloth washing is not required.
Typical applications:
Flue Gas Desulfurization (FGD) Scrubber Sludge
FGD Gypsum Dewatering and Cake Washing for Wallboard
Inorganic Chemicals and Minerals
Pigment Processing
Plastics Resins (Polymers)
Calcium Compounds
Titanium Dioxide
Edible Oil Dewaxing
Roll Discharge:
For discharging very thin, sticky (tacky) cakes.
For discharging dilatent and thixotropic materials.
For applications with very small particle sizes.
Typical applications:
Kaolin Clay
Titanium Dioxide
Pigments
Ceramic Materials
Magnesium Hydroxide
String Discharge:
For discharging cohesive cakes.
For discharging gelatinous cakes.
Typical applications:
Starch
Fruit Juice
Fermentation Broths
Mineral Processing
