Page 320 - Applied Process Design For Chemical And Petrochemical Plants Volume II

Packed Towers 309
.

Fiaure 9-338. Comparison of hydrocarbon sys-
0 1 teis fit to Nutter Correlation at 300 psia (No.
0.2 0.4 0.6 0.8 1 1.2 2.5 Nutter RingTM). Used by permission Nutter
Vapor Rate, Fs Engineering Co., Harsco Corp. and by special
permission of Fractionation Research, Inc.; all
rights reserved.

0.05 0.10 0.15 0.20 0.25 0.30
C-factor C-factor
Figure 9-MA. Efficiency versus C-factor for various metal packings. Figure 9-348. Efficiency versus C-factor for metal rings. Data from
Iso-octane/toluene, 740 mm Hg, retlux ratio 14:1,15-in. I.D. column, Billet (Symposium Series 32, Institution of Chemical Engineers), Lon-
104 bed height. Not Glitsch test data. Note: CMR = Cascade Mini- don (1969). Used by permission of Glitsch, Inc., Bull. 345.
ring@. Used by permission of Glitsch, Inc., Bull. 345.

uid/vapor internal contacting does not create significant ly acceptable to vary the individual heights to fit such
channeling that will reduce the contact efficiency. The requirements as location of return of reflux, multiple feed
base for the initial statement above includes the distribu- positions, and factors of safety on design. Thus one section
tion of liquid, redistribution of liquid, gas or vapor chan- may be 20 ft, another 17 ft, and another 25 ft as long as the
neling, and process surging, plus many other situations process function has been thought out, i.e., the locations
unique to the process conditions. Structured packing of the “breaks” in the packing sections do not interrupt an
heights should be determined by the manufacturer for the important control function by locating the temperature
design conditions. sensor too close to the top or bottom of section, unless
When trying to “balance” the several packed section that location is determined to be the proper sensing loca-
heights as may be required for the process, it is complete- tion. For this, along with other reasons, it is good to pre-