There are two feed operations - backward feed and forward feed operations. A brief explanation of these operations:

Backward feed operation: In this operation, the process of entering the raw feed into last (coldest) effect takes place and its discharge works as a feed for the next to last effect. It is very profitable technique as the cold feed in case the feed is cold, as much less liquid must be heated to the higher temperature existing in the early effects. The same process is used to balance the viscosity of good and also to produce good heat transfer coefficients
Forward feed operation: In this operation, the raw feed goes through parallel to steam flow to effect and the product comes through the last effect. This technique is useful when the feed is hot and is also useful for the high temperature deposit scale and concentrated product change

Features:
Efficiently uses heat from steam to evaporate water
Uses distillation process
Used for concentration of liquids in the form of solutions

Applications areas:
Sugar beet factories
Pharmaceutical industries