Rotary Drum Vacuum Filter are used extensively in the processing of chemicals, pharmaceuticals, cosmetics, foods, minerals and in wastewater treatment and sludge dewatering for industry and municipalities. RDVFs are extremely versatile and provide reliable, continuous liquid/solid separation with minimum operator attention and low maintenance.
Each RDVF filter is specifically designed to handle slurries that produce variations in cake thickness, moisture content and stickiness. The RDVF readily adapts to changes in feed rate and solid concentration and, at the same time, provides superior performance and high production rates.
When to use a RDVF:
1. For general filtration where high rates, low cake moisture and clear filtrate are required.
2. For clarification, where filtrates free from suspended solids are desired, with low filter aid usage.
3. For cake washing, to yield high-purity filter cake using minimum wash liquor.
4. For extraction with high product recovery using minimum wash liquor.
5. For wastewater clarification to reduce or eliminate costly surcharges or the impact on downstream process.
6. For sludge dewatering, to reduce sludge volume by 95% or more, lowering handling and disposal costs.
Factors that affect RDVF rates:
1. Particle size, shape and concentration.
2. Vacuum levels and the cycle time in the cake formation, washing and drying zones.
3. The temperature and viscosity of the suspension.
Auxiliary Equipment:
CCMC offers auxiliary RDVF equipment for a total filtration system: vacuum pumps, vacuum receivers, filtrate pumps, precoat tanks, instrumentation and control panel, conveyors and feed pumps, either as separate items or skid mounted systems.
Options:
Material of construction from plastics to titanium and optional base metal and weld surface finishes are provided as required by the process.
Optional equipment, designed to enhance the RDVF and complete the system, includes cake washing manifolds, cake compression and washing assemblies, shredders, vapor retention hoods and vapor tight construction.
How it works:
The process cycle of the RDVF is continuous. Each revolution consist of cake formation, cake washing (if required), drying and cake discharge.
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. The filtrate is usually removed from the receiver by a 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.
Vapor Containment:
For applications where vapor containment is required, CCMC offers vapor retention and vapor-tight hood designs.
Options & Systems Accessories:
Vacuum and Filtrate Equipment
Vacuum pumps, filtrate pumps, vacuum receivers, instrumentation and controls are available from CCMC. The proper selection and application of these components ensures successful operation of the total filter system. To minimize installation costs and time, CCMC offers “packaged” systems prepiped and pre-wired.
Cake conveyors and Repulpers
CCMC can provide cake conveyors of belt or screw design. A cake shredder can be provided to break up fibrous cake. If the filter cake needs to be converted back into a slurry, then a horizontal shaft repulper can be installed.
Cake washing
Cake washing, to obtain a desired purity or for the extraction of product, is easily accomplished on a RDVF.
Depending upon the amount of wash liquor required, wash pipes utilizing spray nozzles or drip pipes can be installed. In applications where cake cracking occurs and good washing must be obtained. CCMC offers a combination compression and wash assembly. A travelling wash blanket and a series of compression rolls help seal the cracks and distribute the wash liquor. Cake compression also aids in the reduction of cake moisture.
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