Vapor-liquid separator

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File:Vap-Liq Separator.png
A typical vapor-liquid separator including commonly a de-entrainment pad and sometimes an inlet distributor

A Vapor-liquid separator is a vertical vessel into which a liquid and vapor mixture is fed and, in which, the liquid is separated by gravity, falls to the bottom of the vessel, and is withdrawn.[1][2][3][4] The vapor travels upward at a design velocity which minimizes the entrainment of any liquid droplets in the vapor as it exits the top of the vessel.

The feed to a vapor-liquid separator may also be a liquid that is being partially or totally flashed into a vapor and liquid as it enters the separator.

A vapor-liquid separator may also be referred to as a flash drum, knock-out drum, knock-out pot, compressor suction drum or compressor inlet drum.

When used to remove suspended water droplets from streams of air, a vapor-liquid separator is often called a demister.

Where vapor-liquid separators are used

Vapor-liquid separators are very widely used in a great many indusries and applications, such as:

See also


  1. William D. Baasel (1990). Preliminary Chemical engineering Plant Design (2nd Edition ed.). Van Nostrand Reinhold. ISBN 0-442-23440-6.
  2. David H.F. Liu (1997). Environmental Engineers' Handbook (2nd Edition ed.). CRC Press. ISBN 0-8493-9971-8.
  3. Stanley S. Grossel (2004). "Design and sizing of knock-out drums/catchtanks for emergency relief systems". Plant/Operations Progress (AIChE). 5 (3): 129–135. ISSN 0278-4513. Unknown parameter |month= ignored (help)
  4. Stanley M. Walas (1988). Chemical Process Equipment:Selection and Design. Butterworth- Heinemann. ISBN 0-409-90131-8. line feed character in |publisher= at position 13 (help)

External links