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Rotary Vacuum Dryers

Rotary Vacuum Dryers
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Rotary vacuum dryers offer clean, simple and effective method of drying wet cake, powder and even slurry. Labor and energy costs are minimal compared to tray dryers and product losses during handling are also negligible. Additionally valuable organic solvents can be conveniently condensed and recovered.

Working Principle
The drying in a rotary vacuum dryer is a batch operation under vacuum. It is possible to dry heat sensitive materials at well below boiling points of water and solvents. Drying time depends on material being dried, amount of solvent or water to be removed, desired final moisture content, permissible jacket temperature etc. The dryer is available in sizes ranging from 100 liters to 20,000 liters gross volume. The volume of wet material loaded into the dryer is usually restricted to 50% of gross volume.

  • Rotary Vacuum Dryers (RVD) also known as Vanuleuth Dryer, is a cylindrical jacketed vessel with a central agitator having specially designed blades. The blades of this Rotary Vacuum Paddle Dryer (RVPD) are so designed that they sweep the entire internal surface and at the same time turn the material so that all the particles are come in contact with the heated surface.
  • The central agitator shaft is supported on the two end bearings housed in bearing housing in such a way that the alignment remains always intact. This central agitator is driven by means of a Motor & Gear box through the bull Gear.
  • Cooling could also be provided by cold water / brine refrigerant through the jacket.
  • The horizontal shell is jacketed to heat the shell with steam / hot water or any other thermal fluid. Limpet coil is provided instead of jacket if the heating media is fluid.
  • A Dust Catcher consisting of bag filter is provided on the top to prevent the losses of material particles after the drying process.
  • A Condenser of adequate heating surface area is provided wherein the evaporated vapors are condensed and these condensed vapors are then collected in the receiver of suitable capacity, placed beneath the condenser.
  • A Vacuum Pump of adequate capacity is provided & fitted to the receiver of these rotary vacuum dryers to create the vacuum in the dryer shell through the Receiver, Condenser and Dust Catcher.
These rotary vacuum dryer give drying, mixing and breaking effects simultaneously. Wet cake or slurry is fed through charging door, while the agitator is rotating in clockwise direction, vacuum is applied in the dryer and heating media is circulated in the jacket. Evaporation of moisture takes place under vacuum and vapors passes through the dust catcher into the condenser, where it is condensed and collected in the receiver. Dried material is discharged through discharge valve. The lump breaker rods are provided to achieve good drying effect.


This is a high efficiency dryer unit used for drying of wet cake product after filtration. This equipment can be used in drying process of various Pharmaceuticals, Intermediate Compounds, Fine Chemicals, Chemicals, Agro Chemicals, Pesticides, Insecticides, Dyes and Food Products.

  • Very suitable for drying materials which are heat sensitive, as low temperature for drying can be maintained by high vacuum
  • Lowest energy consumption compared to any other batch type dryer due to higher differential temperatures.
  • Higher Thermal Efficiency.
  • Almost 100% recovery of solvents.
  • Heating Temp.: From 30oC to 300oC.
  • Evaporation Rate : 4.12 Kg/ HrlSq. Meter of Heating surface area of water at heating temperature of 100oC.
  • Limpet coil could be provided instead of jacket if the heating media is fluid.
  • Breaker bars of approximately same length as dryer shell can be provided if lump formation is expected during drying.
  • Unique quick opening discharge valve permits direct packing of dry product into bags or drums.
  • Shaft sealing by mechanical seals is also available.
  • Vacuum reduces thermal stress and sustains better colour and texture of dried products compared to those that were air-dried.
  • The vessel is well design to take temperature stresses during vacuum drying. Low power consumption by the use of helical bevel gear box.
  • To remove the condensate formed by steam heating in the hallow shaft, Special rotary joints are also designed to introduce heating media in the hollow shaft.
  • Product Filter is very efficiently used to arrest valuable product carried away with the vapours in a filter bag the arrested product particles are thrown back into the dryer by reverse flow of pulsating air. Generally the product filter is heated to avoid Condensations of vapors in the filter bag.
  • User friendly discharge valve design provides vacuum tight closing when the material is processed and quick opening lever facilities filling of bags when material discharge and packed.
  • Arrangements for nitrogen purging provided. Bag cleaning arrangements with pulsation by nitrogen jet injector provided.
  • Efficient rotary joint to inject heating media into agitator and remove condensate.

  • The hollow rotating agitator shaft imparts heat to the product, scrapes the shell wall, and tumbles the product for maximum heat transfer and discharge product when required.
  • The large heat transfer area available on the wide paddles and hollow shaft give maximum heat transfer efficiency to the product.
  • The scrapers have minimum calculates clearance from the shell to keep the shell clean and increase heat transfer co-efficient.
  • Unique condensate removal mechanism employed in the shaft.
  • Mechanical seal are offered for high vacuum.
  • Shaft is hardened and ground when gland packing is used.

  • User friendly discharge valve design provides vacuum tight closing when the material is processed and quick opening lever facilitates filling of bags when material is discharge and packed.
  • Pneumatically closing, opening, locking and cleaning mechanism is offered for automation.

  • Product filter is very is very efficiently used to arrest valuable product carried away with the vapours in the filter bag. The arrested product particles are thrown back into the dryer by reverse flow of pulsating air.
  • Generally the product filters are heated to avoid condensation of vapors in the filter bag.

  • Mechanicals Seals can be provided instead of stuffing box for certain applications.
  • Pneumatic/Hydraulically operated discharge valves.
  • Solvent recovery system inclusive of condenser, receiver, vacuum system and interconnecting piping.
  • Complete instrumentation for DCS control/Control room operations. Variable speed drives (Frequency inverter).

Our Offered Rotary Vacuum Paddle Dryer can be used in various areas like -
  • Pharmaceutical Industry
  • Intermediate Compounds and Fine Chemicals
  • Organic Chemicals and Agro Chemicals
  • Pesticides, Insecticides and Dyes
  • Food Products

Rotary Vacuum Dryers

Technical Data
Model Total Volume (LTS) Working Volume (LTS) Heating Surface Area (SQ. MTS) Power Required for Agitator Motor (HP) Approx. Size of Dryer ell (Dia x Length)
RVD-250 500 250 3.2 7.5 700 x 1400
RVD-500 1000 500 6 10 900 x 1700
RVD-750 1500 750 7.7 10 1000 x 2000
RVD-1000 2000 1000 8.7 15 1100 x 2100
RVD-1250 2500 1250 10 20 1200 x 2250
RVD-1500 3000 1500 11.6 20 1260 x 2400
RVD-2000 4000 2000 16.7 30 1200 x 3600
RVD-3000 6000 3000 17.7 40 1600 x 3000
RVD -4000 8000 4000 23.5 50 1600 x 4000
RVD-5000 10000 5000 27.3 60 1700 x 4400

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