The Artisan Rototherm-D is a specialized slow-speed dryer, designed for continuous vacuum drying or post-drying of free-flowing solid materials. The Rototherm-D is a jacketed, mechanically-agitated dryer, that continuously removes moisture or solvents from powders and bulk solids under vacuum. It is especially useful for diffusion-limited drying applications where long residence times are required.

Rototherm-D operating principle


The Feed, being moist powder or bulk solids, enter into the Rototherm-D at one end. The horizontal shell and the specially designed rotor are heated by water, steam, or hot oil. The low speed helical mixing bars agitate the product continuously, while gently churning and continuously conveying it to the discharge end of the dryer in a plug flow manner.
Vacuum minimizes drying temperature and avoids thermal degradation of heat sensitive materials. An adjustable weir at the discharge end keeps the product level in the dryer between 25% and 75% full. Adjusting the height of the weir or changing the feed rate will allow to control the residence time. The dry product discharge is collected either by batch in a sealed vessel or continuously after passing through a vacuum lock vessel.

Process Benefits

The Rototherm-D offers the following benefits over batch dryers:

  • Low temperature and shear reduce product degradation
  • Continuous process eliminates variations in product quality between batches
  • High heat transfer area-to-volume ratio
  • Adjustable drying time from 20 minutes to several hours


The Rototherm-D has various fields of application

  • Drying heat sensitive powders and bulk solids
  • Drying shear sensitive powders and bulk solids
  • Diffusion controlled drying applications
  • Further dewatering readily dried sludges and press-cakes
  • Sublimation of powders
  • Solid state polymerization/polycondensation

The Rototherm-D is a product in development by Artisan. If you have an application that you believe would benefit from Rototherm-D’s operating principles, then our product development team would be happy to work with you to incorporate this technology into your projects.

Download the Artisan Rototherm-D Brochure
For more information please refer to the Artisan Industries website.