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Freeze drying (lyophilisation) has been used industrially for decades to preserve foodstuffs and organic materials. However, traditional tray-type freeze dryers are slow and labor intensive. Hosokawa's Nauta® Active Freeze Dryer eliminates these drawbacks and is a big step forward in the field of freeze drying bulk solids as well as in powder technology in general.

Active freeze drying offers unique possibilities for freeze drying various types of materials in one processing step, always resulting in a fine loose powder which is directly available from the product collector. Material consistencies can range from solutions, dispersions to paste and even wet solids. The key benefits of this technology are efficiency, minimal handling and a consistent, high product quality.

  • Efficient - The Active Freeze Drying process is faster and less labor intensive than the traditional tray freeze drying process. This new technology produces lump free, free-flowing powders in one single step. Consequently, the handling is significantly shorter and simpler (no manual handling or de-lumping steps), saving you time and money!
  • High Quality - Due to this alternative and much faster method of freezing the substrate, the structure of the end product is different and in the majority of cases, will result in an amorphous-like structure with better redispersibility and free-flowing properties. In addition to this, the particle size of the final product is often extremely fine and uniform.
  • Contamination-free - There is hardly any room for contamination, which makes the Active Freeze Dryer ideal for sterile materials.
  • Compact - The Active Freeze Dryer is a compact piece of equipment that requires much less floor space than conventional tray drying installations which usually comprise of horizontal vessels, freezer and tray handling machinery. Hosokawa Micron has converted all of this into a single vertical dryer.
  • Broad equipment range - The Active Freeze Dryer is available in a broad range of different sizes, from 1 up to 1000 liters.

In an Active Freeze Dryer, the product is first frozen dynamically by moving it in a specially designed chamber. Whether the material to be dried starts off as a liquid, granular solid or paste, the forced motion inside the drying chamber ensures that it freezes in the form of free-flowing solid granules.

Once the product is fully frozen, a deep vacuum is applied and the sublimation starts. Heat applied to the vessel jacket is effectively distributed throughout the product due to the dynamic environment. The initially coarse, frozen granules gradually shrink as the ice structure connecting the frozen material sublimes, yielding a loose powder consisting of fine, dry particles.

As the solvent disappears, the product temperature starts to rise until it equals the jacket temperature. This marks the end of the drying process. Once the vacuum has been released, the chamber is opened and the powdered product can be discharged.

Typical applications include pharmaceuticals like antibiotics, proteins, collagens, APIs and electrolytes. Numerous successful applications are also found in food and food additive applications like herbal extracts, milk derivatives, enzymes, broth extracts, vegetables, lipids, insects, flavors, fibers, proteins and soups. This new technology has also proven its suitability to the freeze drying of special materials like nano-materials, polymers, ceramics, pigments, fillers, lime stone, catalysts, glass powder and salts.

Description

In an Active Freeze Dryer, the product is first frozen dynamically by moving it in a specially designed chamber. Whether the material to be dried starts off as a liquid, granular solid or paste, the forced motion inside the drying chamber ensures that it freezes in the form of free-flowing solid granules.

Once the product is fully frozen, a deep vacuum is applied and the sublimation starts. Heat applied to the vessel jacket is effectively distributed throughout the product due to the dynamic environment. The initially coarse, frozen granules gradually shrink as the ice structure connecting the frozen material sublimes, yielding a loose powder consisting of fine, dry particles.

As the solvent disappears, the product temperature starts to rise until it equals the jacket temperature. This marks the end of the drying process. Once the vacuum has been released, the chamber is opened and the powdered product can be discharged.

Typical applications include pharmaceuticals like antibiotics, proteins, collagens, APIs and electrolytes. Numerous successful applications are also found in food and food additive applications like herbal extracts, milk derivatives, enzymes, broth extracts, vegetables, lipids, insects, flavors, fibers, proteins and soups. This new technology has also proven its suitability to the freeze drying of special materials like nano-materials, polymers, ceramics, pigments, fillers, lime stone, catalysts, glass powder and salts.

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