Artisan Industries designs and manufacturers high end evaporators under the brand name Rototherm®. Artisan Industries designed and manufactured these evaporators since the 1960’s and they have installed more than 500 units worldwide.

Advantages of the Rototherm®

  •   Fully–wetted process wall at all evaporation- and feed rates, hence less fouling
  •   Thin film unaffected by gravity, thus a high turn-down ratio
  •   Higher heat flux due to more uniform film
  •   Considerably less solvent required for cleaning
  •   Readily accessible external bearings and double mechanical seals
  •   No internal bottom bearing in contact with the process stream
  •   Easy installation and maintenance

The Rototherm® has several executions.

  • Rototherm-E: Designed as an evaporator or finisher with a liquid product stream as end-product.
  • Rototherm-P: Designed to go one step further as it produces a dry output directly from a liquid feed.
  • Rototherm-D: Designed to post-dry solid streams of material.
  • Protherm-50: Designed as a versatile test unit

Rototherm® – Design features

Rototherm® units may be designed for co-current or counter-current liquid/vapour flow.

RotothermE - CocurrentCo-Current
The liquid and resulting vapour travel in the same direction. As such this method is a recommendation when only partial product concentration is desired. At the same token, it is better for higher viscosity applications. This method furthermore minimises liquid entrainment into the vapour ducting.

RotothermE - CountercurrentCounter-Current
The liquid and resulting vapour travel in opposite directions. As such this method is preferred when high product concentration is desired.

Rototherm® – Principle of operation

Rototherm’s high-speed rotor creates centrifugal force, which keeps the product feed against the heated cylinder wall. A turbulent thin film between the rotor blades and wall covers the entire heated surface at all times, independent of the feed rate or evaporation rate.
The turbulent thin or wiped film creates high heat transfer efficiency, thus minimizing the area required for evaporation. The film is continuously renewed by the incoming feed as the progressively more concentrated material moves towards the bottoms discharge nozzle. Product residence time in the Rototherm is generally measured in seconds, minimizing degradation of heat-sensitive materials.
Rototherm Principle

Rototherm – Principle of Operation

Rototherm allows for up to 99% evaporation in a single pass. As a consequence it can often concentrate dilute solutions to powder directly. Markedly dry spots do not exist, as the process wall, unaffected by gravity, remains fully wetted at all evaporation rates.
When used as a continuous reactor, the Rototherm’s multiple feed points and temperature zones, its controlled residence time, and simultaneous evaporation of reaction by-products provide total flexibility for complex reactions. Rototherm’s short residence times allow reactions at higher temperatures than conventional reactors. As such increasing the rate of reaction without compromising product quality and yield.
Artisan designs each Rototherm for optimum performance for its specific application. Rototherms can range in size from 1 dm2 to 23 m2 of heated surface. A single unit can evaporate up to 2,000 kilograms of solvent per hour. Rototherm jackets can be designed for hot water, steam or hot oil heating. Construction materials include stainless steel (300 series and Duplex), carbon steel, nickel, Inconel®, Monel®, Hastelloy®, and titanium.