Thin Film Evaporator

Overview

The Thin Film Evaporator combines more than 60 years of experience from Luwa, Samesreuther and Canzler and is available in a variety of rotor designs, horizontal or vertical orientation, and cylindrical and conical shape for co-current and counter-current vapour flow. A distribution ring on the rotor distributes the liquid evenly and rotor blades spread the liquid as a thin film of min. 0.5 mm over the heat transfer surface. Prior to each rotor blade a bow wave is formed and, in the gap between the rotor blade and the heating surface, fluid is supplied from this bow wave into a highly turbulent area with intense heat and mass transport, yielding good heat transfer performance even with viscous products. The rotor stabilises the liquid film at high evaporation rates, allowing evaporation in the area of nucleate boiling without film rupture, and centrifugal force presses the liquid film against the heating surface to avoid formation of an insulating vapour layer, enabling extremely high specific evaporation rates. Typical designs include the cylindrical body designs DVN ("LUWA") and DVB ("SAMBAY") with vertical orientation, the conical body design DKV ("SAKO"® KV) with vertical orientation and DKH ("SAKO"® KH) with horizontal orientation; SMS installs rigid blade rotors in the DVN and in the conical thin film evaporators suitable for products with viscosities up to 70,000 mPas. In the thin film evaporators type DVB rotors are equipped with hinged wiper blades that centrifugal force presses to the heating surface to achieve high evaporation ratios at low flow rates and handle products with fouling tendency, and for separation of monomers from pre-polymers and polymers there are vertical thin film evaporators type DVF with spring wiper elements and DVS with Smith-Rotor, with specially designed wiper elements made of PTFE or graphite that are partially spring-loaded. SMS has supplied more than 6,000 thin film evaporators to more than 50 countries. Explicitly stated applications include distillation, separation, concentration, stripping, deodorisation, degassing and reaction. The equipment is described for processing heat-sensitive, viscous, fouling and foaming products and for continuous processing. The adjustable rigid blade rotor in conical evaporators is noted as a decisive advantage for degassing applications where low‑boiling components have to be reduced to a minimum, and vertical designs are used to feed product at the upper end with volatile components evaporating and being discharged at the upper or lower end while entrained droplets or foam are removed from the vapour.