Evaporation Process for Falling Film Tubular Evaporator

Evaporation takes place under vacuum, atmospheric pressure, positive, or a combination depending on product heat sensitivity and viscosity. Usually, vacuum is involved.

The process liquor to be evaporated is distributed uniformly as a film along the inside of the heat exchanger tubes. Steam (or vapor) is applied on the heating media side of the tubes in an amount suitable for the required evaporation.

Heat is transferred through the tube wall to the liquor, which starts boiling at a temperature corresponding to the pressure inside the tubes.

The concentrate and vapor flow from the bottom of the tubes to a separator, where they are separated. The concentrate is pumped out from the bottom of the separator, while vapor is condensed in a condenser or in the next stage.

Evaporator

Falling Film Tubular Evaporators are available in single-stage or multi-stage options. Multi-stage evaporation is generally most cost-effective as reuse of vapor from the previous stage into the next enables recovery of residual heat as the heating medium.

Operating costs can also be reduced by using a thermal vapor re-compressor (TVR) or a mechanical vapor re-compressor (MVR), or a combination of both.