Phase Separations

Distribution Baffles

Distribution baffles a.k.a calming baffles are perforated baffles typically installed downstream of the inlet device in horizontal 3 phase (gas/liquid/liquid) or 2 phase (liquid/liquid) separators covering the entire liquid section. In some cases, depending upon the type of inlet device used, it may be full diameter for 2 phase gas/liquid separation and/or 3 phase gas/liquid/liquid separation to minimize vapor maldistribution.

Its main function is to dissipate turbulence and ensure uniform distribution of liquid across vessel cross-sectional area for effective and optimized liquid/liquid separation. The distribution baffles will assure the interface levels in the liquid section is clam and stable and the overall design will meet and/or exceed the separation objective.

Depending upon the criticality of separation objective, cross-sectional velocities, available spacing, downstream equipment etc, often (2) distribution baffles are employed with varying open area ranging from as low as 21% to a maximum of 50% and the hole size is selected based on potential of solid foulants.

In case of heavy solid foulant or waxy nature of fluids, often larger holes size with a cut-back at the bottom will be used and/or cap distribution baffle with be employed.

Motion Baffles

Often the distribution baffles are used as motion baffle to mitigate the motion affects in a separator on floating platforms. Specific pitch and roll tend to slosh the liquid inside the separator resulting in:

  • Unstable interface level thereby affecting liquid liquid separation efficiencies
  • Excessive liquid loading to demisting device because of liquid re-entrainment from liquid surface
  • Liquid carry over through the demisting devise as the drainage head might not be sufficient due to rise in the liquid level on one side.


The challenges often lie is selecting the correct open area and number of baffles and hence CFD can be an effective tool for optimization.