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Packed bed pressure drop and flooding calculations are
based on the Eckert generalized pressure drop correlation. The
flooding calculation has been shown to be nonconservative. The
problem is most pronounced in low pressure columns. For instance
Eckert will report an atmospheric column stripping air with
4 GPM/ft² water irrigation rate operating at roughly 90% of flood
as operating in the low 70%s.
Charles Holland reports that Bolles and Fair suggest using a 1.32
safety factor (multiplier) on the Eckert correlation for a 95% confidence estimate of
flooding. They further suggest a 2.2 safety factor on the Eckert correlation for
a 95% confidence estimate of the pressure drop.
Table of Packing F Values
Packing Type

6mm

13mm

19mm

25mm

38mm

50mm

75mm

100mm

Berl Saddles, ceramic

2950/m

790/m



360/m

215/m

150/m





Intalox Saddles, ceramic

2380/m

660/m



320/m

170/m

130/m

70/m



Intalox Saddles, plastic







105/m



69/m

50/m



Pall Rings, metal







157/m

92/m

66/m





Raschig Rings, ceramic

5250/m

2000/m

840/m

510/m

310/m

215/m

120/m



Raschig Rings, metal





730/m

450/m

270/m

187/m

105/m



References:
John Eckert et. al., "Fundamentals of Multicomponent Distillation,"
Chemical Engineering Progress (January 1966) p. 5967.
John Eckert, "Selecting the Proper Distillation Column Packing,"
Chemical Engineering Progress (March 1970) p. 3944.
John Fair, PhD. et. al., Perry's Chemical Engineer's Handbook 6th Ed.
(New York, New York: McGrawHill Book Co., 1984), p. 1822  1824.
Charles Holland, PhD, Fundamentals of Multicomponent Distillation
(New York, New York: McGrawHill Book Co., 1981), p. 470  474.
Copyrighted 2000, 2004 Last updated 19Sep04
