A vapor–liquid separator drum is a vertical vessel into which a liquid and vapor mixture (or a flashing liquid) is fed and wherein the liquid is separated by gravity, falls to the bottom of the vessel, and is withdrawn. 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 Souders-Brown equation has been the tool for obtaining the maximum allowable vapor velocity in vapor-liquid separation vessels (variously called flash drums, knockout drums, knockout pots, compressor suction drums and compressor inlet drums).
|V||Maximum Allowable Vapor Velocity (m/s)|
|k||Vapor Velocity Factor ( 0.107 m/s when the drum includes a de-entraining mesh pad) (m/s)|
|p2||Vapor Density (kg/m3)|
|p1||Liquid Density (kg/m3)|