Bottom Feed and Reboiler Return Spargers

When the bottom feed or reboiler return enters the column with a high velocity, or when there is a concern about excessive turbulence at 

Where pressure drop is critical, a sparger pipe with the bottom quadrant cut out (rather than perforated) is sometimes used, but at the penalty of inferior vapor distribution. Similarly, the sparger can be entirely eliminated and substituted by a dog house baffle parallel to the direction of fluid entry. This baffle is somewhat wider than the nozzle diameter and stretches from wall to wall parallel to the direction of the incoming fluid. The author is familiar with one experience where addition of a dog house baffle eliminated a packed-tower vapor maldistribution problem. 

The main consideration in the design of a column outlet is to achieve the required phase separation. For liquid outlets, providing the required surge capacity is important as well. 

The presence of vapor in liquid outlet lines has been a major troublespot in distillation and absorption columns. Numerous case histories have reported premature flooding, column instability, and pump cavitation and erosion caused by presence of vapor in liquid outlet lines (12, 85, 208, 255) the author is familiar with a few additional 

Arrangements such as bottom sumps, chimney trays, side-draw drums, and surge drums are usually designed for avoiding the presence of vapor in the liquid outlet. On the other hand, downcomer trapouts are usually designed to allow for the presence of vapor in the outlet liquid. 

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