The falling film evaporator consists of shell and tube heat exchanger called as calandria that is mounted in vertical position.
The liquid product enters the evaporator at the head and is evenly distributed to the heating tubes.
A thin film enters the heating tube and flows downwards at boiling temperature through the steam in the jacket and is partially evaporated.
The vapour is separated from the liquid in vapour separator and the concentrated liquid is collected at the bottom or transferred to the next stage.
The falling film evaporators can be single effect or multiple effects depending on the capacity.
Falling film evaporators can be operated with small temperature differences between the heating media and the boiling liquid and they also have short product contact time. These characteristics make the falling film evaporator particularly suitable for heat sensitive products and it is the most frequently used evaporator.
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