Rototherm® E Thin-Film Evaporator

Rototherm® E is our most popular evaporator design. We have been designing and manufacturing Rototherm® E units since the 1960s, and have more than 500 installations worldwide. Over the last 50 years, a number of enhancements have been made to improve Rototherm® E’s processing capability.


Rototherm® E is designed for applications where the feed stream entering the evaporator AND the concentrated product stream exiting the evaporator are both pumpable fluids (liquids, pastes, or sludges).

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

Co-Current – The liquid and resulting vapor travel in the same direction. This method is preferred when only partial product concentration is desired.
The concentrating liquid film and generated vapor travel in the same direction within the heated process section. This design is used for partial product concentration and higher viscosity applications. This design also minimizes liquid entrainment into the vapor.

Counter-Current – The liquid and resulting vapor travel in opposite directions. This method is preferred when high product concentration is desired.

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    • [1] Solvent Vapor Out
    • [2] Process Wall
    • [3] Rotor Blades
    • [4] Feed In
    • [5] Heating Medium In/Out
    • [6] Bottoms Discharge
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Centrifugal force produced by the rotor blades [3] holds a thin film of feed material [4] against the heated process wall [2]. The turbulent thin film between the rotor blade and process wall covers the entire heated section at all times, regardless of feed or evaporation rates. This film is constantly renewed by the incoming feed [4] as the progressively more concentrated material is displaced towards the bottom discharge nozzle [6]. High vacuum can be maintained in the system to minimize processing temperature. Degradation of heat sensitive materials is minimized because the residence time is so short, generally measured in seconds.