Overflow redistributor

Each tray in a tower is inherently a vapor-liquid redistributor. The outlet weir, or more exactly the crest height of the liquid overflowing the weir forces the liquid to flow evenly across the tray. Even if the weir... 

Liquid is withdrawn from the redistributor either via an overflow pipe or using a submerged drawoff nozzle. When an overflow arrangement is used, the drawoff may frequently run dry, and flow to downstream units may be intermittent or unstable. When a submerged drawoff nozzle is used, excessive drawoff rates may lower the liquid level in the redistributor and cause poor distribution to the bed below. 

Redistributors usually provide insufficient residence times for vapor disengagement (especially if an overflow pipe is used), and venting must be completed downstream of the column outlet. Downstream piping must be sized for self-venting flow (Fig. 4.5). 

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See also in sourсe #XX -- [ ]

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