A Thin film evaporator (ATFE) consists of two major assemblies – jacketed shell and a rotor assembly which rotates at high speed inside the shell. The feed is inserted into the evaporator at the top, tangential to shell and it is distributed along the shell via a distributor. After this, the rotor works to spread the feed into a thin film and agitate it further. The liquid is distributed in the form of a thin film on the heated wall where the heat transfer takes place.

Heating medium passing through the jacket evaporates the volatile component in feed. The vapor generated flow counter currently to feed and gets cleared in entrainment separator before leaving through vapor nozzle. The concentrate product comes out at bottom.