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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 non-conservative. 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. 59-67.
John Eckert, "Selecting the Proper Distillation Column Packing,"
Chemical Engineering Progress (March 1970) p. 39-44.
John Fair, PhD. et. al., Perry's Chemical Engineer's Handbook 6th Ed.
(New York, New York: McGraw-Hill Book Co., 1984), p. 18-22 - 18-24.
Charles Holland, PhD, Fundamentals of Multicomponent Distillation
(New York, New York: McGraw-Hill Book Co., 1981), p. 470 - 474.
Copyrighted 2000, 2004
Last updated 19Sep04
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