2 phase separator design calculator – Vertical Knock Out Drum

This is a sample of the 2 Phase separator design calculator. To access the working calculator, please sign up for free membership trial.

This calculator can be used to size a vertical two phase separator for removal of liquid droplets or a vertical Knock Out Drum or Reflux Drum vessel. This calculator determines the minimum required size of such a separator to handle the given flowrates based on terminal settling velocity of liquid droplets (also reported in results). The minimum requirement of residense time between High / Low liquid levels and High High / Low Low alarm levels arise out of process control and alarm requirements. These levels should depend on the project standards. It should be noted that the vessel size calculated here is the minimum approximation and the recommended size should be bigger than this size, with a margin.

Liquid Flowrate m3/hr
Gas Flowrate m3/hr
Liquid Density kg/m3
Gas Density kg/m3
Liquid Viscosity cP
Gas Viscosity cP
minimum liquid droplet diameter to be separated micron
L/D ratio (TL-TL length/dia.)
Desired residense time between HHLL (alarm) and HLL minutes
Desired residense time between HLL and LLL minutes
Desired residense time between LLL and LLLL (alarm) minutes
Type of vessel head
Gas bubble terminal velocity m/s
Vessel Volume m3
Vessel Diameter m
Vessel Lengtgh (TL-TL) m


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