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