Page 337 - Applied Process Design For Chemical And Petrochemical Plants Volume II

326 Applied Process Design for Chemical and Petrochemical Plants

This packing is a woven wire fabric of parallel corrugat- Distill a diethanolaminemethanolamine mixture to pre
ed elements and is completely self-wetting. It does not duce a 99.0 wt% DEA. distillate product and a 95.0 wt% TEA
require pre-flooding to attain the wetted condition. This bottoms product. The design material balance is as follows:
packing has a flat surface of approximately 150 ft2/ft3, and
a free area > 90%. Feed Distillate Bottoms
In operation, the liquid flows downwards in a zig-zag lb/hr mol/hr lb/hr mol/hr lb/hr mol/hr
pattern. See Figure 9-6EE. DEA 5,000 47.6 4,740 45.1 260 2.5
TEA 5.000 33.5 5 0 0.3 4,950 33.2
Example 9-7: KochSulzer Packing Tower Sizing (used by Totals 10,000 81.1 4,790 45.4 5,210 35.7
permission, Bulletin Hs-1, Koch Engineering Co. Inc.)

The following typical design problem illustrates the cal- To preclude thermal degradation of the amine solution,
culation procedure for Koch Sulzer Packing. A comparison the reboiler pressure must be limited to 10 mm Hg absolute
of a KS Packing design and a Flexiring design will result in pressure. Total allowable pressure drop is 3 mm Hg.
(for 2-in. metal Pall rings) top = 7.5-ft D and bottom =
8.5-ft D. See Figures 9-51-54. Solution
0.5 1 .o 1.5 2.0 Distillation calculations result in a reflux ratio L/D =
I I I I I I 0.8, with 4 theoretical trays for rectification and 4 theoret-
ical trays for stripping, or a total of 8 trays. The design heat
balance (neglecting heat losses) is as follows:

Heat Out -- -- Btu/hr
lb/hr
State
OF Btu/lb
Distillate 4,790 Liquid 296 160 766,000
Bottoms 5,210 Liquid 381 240 1,250,000
Ovhd. Cond. - - - - 2,470,000
10,000 4,486,000
n. -!T 0.6 1 1 1 Heat In 10,000 Liquid 314 180 1,800,000
Feed
Reboiler (Q) By Difference 2,686,000
10,000 4,486,000
I
1” 0.2
Column Sizing fw Koch Sulzer Packing
I
I
I
Bottom Section
The bottom section vapor loading is controlled by the
reboiler vapor where:
8
f V, = QJlv TEA = 2,686,000/192 = 14,000 lb/hr
56
E
E4 The design mass velocity at 10 mm Hg (Figure 9-52) is
460 lb/hr-ft2. Applying the “f” factor correction for six car-
2 bon atoms (Figure 9-53) results in

0.5 1 .o 1.5 2.0 2.5 f = 1.12
A = 14,000 (1.12)/460 = 34.1 ft2
F, = V, .~pv (LB‘~ /SEC-FT~~
D = 6.6 ft, use 6 ft 9 in.
Column Diameter. ................. .20 inches V, = VJ3600 (35.8) pv
System ..................... cis-trans-decalin = 14,000/3,600 (35.8) (0.0031) = 35 ft/sec
Top Pressure .................... .20 mm Hg. F, = V, (pV)l/2 = 35 (0.0557) = 1.95 lb1/2/ft1/2 sec
Reflux Ratio ......................... Infinite
Considering the reboiler as a theoretical tray, for 3 the-
Figure 9-51. Characteristics of Koch/Sulzer packing, Gas loading oretical trays the packing height for an HETP of 7 in. is 7
factor, F, versus HETP, pressure drop, and packing hold-up. Note: V,
= superficial gas velocity, Wsec and pv = vapor density, IbM. Used (3)/12 = 1.75 ft. This requires 4 standard elements which
by permission of Koch Engineering Co., Inc., Bull. KS-1 and KS-2. are 6.7 in. deep, or 80 ft3 of packing.