for Powders & Bulk Solids



The Nauta conical screw dryer is a universal vacuum dryer for drying materials such as powders, granules, pastes and viscous slurries, especially when these products are heat-sensitive, contain solvents and are toxic or explosive.

The Nauta conical screw dryer is capable of handling products that become heavy and sticky during drying and can also be used for vacuum operations such as reaction/crystallisation, heating/cooling, sterilization, liquid/solid separation, and de-aeration.


Nauta vacuum dryer working principle Nauta vacuum dryer working principle

The Nauta conical screw dryer is a convective dryer with high drying efficiency. The rotating cantilevered (free hanging) mixing screw conveys the product from the bottom of the vessel to the product surface. The mixing screw is suspended from an orbital arm, which rotates the mixing screw along the conical inner vessel wall causing convective mixing of particles and shear.

The thermal energy required for the drying process is transferred to the product via a heated jacket, which can be heated by various media such as steam, hot oil and water. The jacket ensures rapid distribution of heat into the product in combination with efficient mixing.

The vacuum inside the dryer allows vapour to be removed at low temperatures, which makes the Nauta vacuum dryer ideal for drying heat-sensitive products. The vapours are removed through a dust filter fitted on top of the vessel. This prevents the dust from entering the vacuum system.

The Nauta vacuum dryer is equipped with a condenser with a solvent recovery tank. This condenser can be installed before or after the vacuum pump, depending on the properties of the solvents. The moisture content of the product can be controlled by monitoring the weight of the condensate or by using a Hosokawa Sampler to take samples from the product inside the dryer under vacuum.

  • Key features
    • Batch volumes ranging from 5 to 22,000 litres
    • Multi-purpose and multi-processing
    • Efficient batch drying of everything from loose powders to heavy pastes and viscous liquids
    • No segregation and no product degradation
    • Interchangeable screw agitator for dryers larger than 20,000 litres
    • Full compliance with international standards such as FDA, cGMP, EHEDG
    • Automated cleaning solutions with our patented CIP filter and CIP skids
    • Sterile processing (SIP) possible
  • Applications

    The Nauta conical screw dryer is designed for vacuum drying solid based materials, but can be used in a wide range of other process applications requiring thermal processing or vacuum treatment of solids, including:

    • Mixing / Drying under vacuum
    • Alkalization, solid-gas reactions
    • Cooling of solids and liquids
    • Crystallization
    • De-aeration of pastes and liquids
    • Sterilization of products
    • Wet agglomeration and granulation of solids

    This combination of several processes in one vessel offers tremendous savings on investment costs, labour, and space.

  • Models

    Nauta conical screw dryers are available in many sizes and are custom made to suit your application. A number of models with their typical characteristics are described below. Please note that these values are indicative only. Detailed information on all models is available on request.

    Model (water filling)[l]5805001000500012,00022,000
    Height [mm] 1420 2660 3920 4460 6840 8450 9950
    Width [mm] 600 900 1470 1720 2710 3730 4290
    Net volume (powder filling) [l] 4.3 68 430 840 4500 12,000 22,000
    Jacket surface area [m²] 0.13 0.69 2.84 4.58 13 25 33
    Max. evaporation water * [kg/h] 1 5 25 35 100 190 250
    Max. evaporation ethanol * [kg/h] 3 12.5 60 85 250 400 600

    * Jacket surface temperature T=50°C

    Laboratory & pilot vacuum dryers

    Our laboratory & pilot vacuum dryers are small vacuum drying systems that have been specially developed for use in laboratories. They are multi-purpose systems for wide-ranging applications.

    The complete systems, including all of the necessary ancillaries, are built on stainless steel skids with wheels. They are very suitable for process development activities, experimental purposes and for fine-tuning for optimal process parameters. The laboratory dryers are available from 5 litres to 20 litres and the pilot dryers from 40 to 120 litres.

    Standard industrial dryers

    Our industrial dryers are available in sizes of up to 22 m³. They are designed and built according to industry standards such as Stoomwezen, PED, TÜV, Lloyd’s, ASME, Afnor, ISPLE etc. and are available in all grades of stainless steel, Monel, nickel, titanium, Hastelloy, etc.

    Bespoke systems

    Hosokawa Micron has 90 years of experience in designing and manufacturing vacuum dryers and turn-key vacuum drying systems. This experience in designing complete installations with process guarantees and validation makes us a valuable partner for the realisation of total powder processing solutions. Our expert design and engineering team would happily work with you on a tailor-made design for any of our dryers or drying system.

  • Ancillaries

    Our expert design and engineering team would happily help you specify the right ancillary equipment to compliment the Nauta® conical screw dryer. These ancillaries may include:

    • Vacuum filter
    • Sampler
    • Heating/cooling skid
    • Ball segment valve
    • Lump breaker
    • Liquid injection
    • Controls
    • CIP/SIP skid


Nauta vacuum dryer / drying system

Hosokawa Micron has been developing innovative solids processing systems for more than a century. As a result, we can draw on an unparalleled amount of know-how when designing new drying systems. In a drying system, the equipment, process steps and interacting parameters must all work together as an integral solution in order to ensure the optimal functionality, quality and efficiency of your total system. That's why we carefully select, configure and integrate all the components and processes when designing a drying system.

Thanks to our long-standing experience, we are the ideal partner to transform your drying operation into a bespoke powder processing system, from incoming base ingredients to final products.


Energy-efficient vacuum dryer

Drying is responsible for more than 15% of energy consumption in modern industrial processes. This makes energy efficiency an important factor when designing a conical dryer. Hosokawa Micron is an expert in developing advanced conical screw dryers and we put a lot of our own energy into developing screw dryers that will save you energy!


This video takes a deeper look at Nauta Mixers & Dryers, their principle of operation, history and development of Nauta technology, benefits, features and functions as well as common mixing and drying applications.


Hosokawa Micron powder processing Test Centre in Doetinchem (Netherlands)

Our Test and Process Development Centre in the Netherlands offers unique possibilities for testing your product to determine the most efficient process, system or plant prior to final design. We can provide laboratory-level as well as production-sized trials. Whether you wish to test a single machine or a complete powder processing system, the same skilled and experienced staff are here to help ensure that you are entirely satisfied with the results.

We offer process equipment and technologies from individual units to large scale bespoke system solutions. Our principle is to deliver high performance yet affordable solutions that meet our customers' demands and long term challenges.

We also have rental equipment available for batch drying.


To learn more about our powder processing equipment and systems, contact us:



Hosokawa Micron B.V. is certified according to ISO 14001. Our certification covers all environmental themes of ISO 14001: air, soil, energy, waste, water, noise and hazardous substances. In addition, Hosawa Micron was awarded an EcoVadis Silver Medal for its sustainability achievements. EcoVadis determined that the company was among the top 15% of companies rated by EcoVadis in the special machinery industry.

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