Page 294 - Applied Process Design For Chemical And Petrochemical Plants Volume II

Packed Towers 283

of Curves IS Pressure
ches of WaterlFoot
Approximate Flooding

0.01 0. I I IO 3
UG m

L = LIQUID RATE, LBS /SEC, SQ FT g = VISCOSITY OF LIQUID, CENTIPOISE.
G = GAS RATE, LBS /SEC , SO FT g, = GRAVATATIONAL CONSTANT 32 2 FT /fSEC 8dSEC
Figure 9-21A. Sherwood-type correlation for flooding gas rate at a 0,. =LIQUID DENSITY. LBS /CU FT G' =GAS RATE. LBS /HR
L' =LIQUID RATE, 1% /HR
po = GAS DENSITY, LBS /CU FT
given liquid rate. Used by permission of Zenz, F. A., Chemical Engi- F = PACKING FAClOR a /e'
neering, Aug. (1 953), p. 181 ; all rights reserved.
Figure 9-21 C. Generalized pressure drop correlation essentially
equivalent to Figure 9-21 B. Used by permission of Norton Chemical
10 0 Process Products Corp.
60
40
Note differences in some symbol units for various GPDC
charts.
20
For tower sizing:
10
06 1. Calculate using ordinate value = CsF0~3~0.05
2. Calculate allowdbk gas mass velocity (ft/sec), C,

c 02
Flow parameter at maximum flow location:
01
L
FP = - [p<; /pL, (9- 18)
G
OW

OM Strigle [ 1391 reports that the correlation of Figure 9-21-
F (and probably Figure 9-21C, because it is from the same
0 01 data) predicts pressure drops to an accuracy of 21 1 %, and
001 002 004 06 01 02 04 06 10 20 40 60 I00
suggests that this is probably the best attainable with avail-
able data for the many different sizes and shapes of pack-
ing. Better accuracy can be attained only when using data
Figure 9-21 B. Recent generalized pressure drop correlation. Note: Y
= viscosity of liquid in centipoise. Used by permission of Norton specific to a particular packing family of sizes, such as the
Chemical Process Products Corp. Nutter, Norton, and Glitsch respective packings noted
hereafter. For Figures 9-21-B through H, at high liquid
rates, pressure drop may become somewhat greater than
Gh = gas mass velocity, Ib/(ft') (hr) obtained from the charts (GPDC), particularly for the
p~ = gas mass density, lb/ft.'
p~ = liquid density, Ib/ft.? smaller packing sizes. For the higher liquid rates, use the
Y = kinematic liquid viscosity, centistokes, note: centis- particular charts of the manufacturer of the packing for
tokes = centipoise/ (p1./62.4) the type and size, rather than the GPDC.