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14-86 EQUIPMENT FOR DISTILLATION, GAS ABSORPTION, PHASE DISPERSION, AND PHASE SEPARATION
Installed cost, dollars/tray
10 4
10 3
10 2
Quantity factors apply to all types of trays
Bubble-cap trays
(stainless steel)
that for Fig. 14-80 and Table 14-17, the effective cost date is January
1990, with the Marshall and Swift cost index being taken as 904.
As indicated above, packed column internals include liquid distributors,
packing support plates, redistributors (as needed), and holddown
plates (to prevent movement of packing under flow conditions). Costs of
these internals for columns with random packing are given in Fig. 14-81,
based on early 1976 prices, and a Marshall and Swift cost index of 460.
1
2
3
4
5
6
7
3.00
2.80
2.65
2.50
2.30
2.15
2.00
8
9
10
11
12
13
14
1.80
1.65
1.50
1.45
1.40
1.35
1.30
15
16
17
18
19
20
30
40+
29
39
Valve trays
(stainless steel)
1.25
1.20
1.15
1.10
1.05
1.00
0.98
0.97
Stamped turbogrid
trays (stainless steel)
Valve trays
(carbon steel)
Sieve trays
(stainless steel)
Sieve trays
(carbon steel)
or
Bubble-cap trays
(carbon steel)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Tower diameter, ft
FIG. 14-80 Cost of trays. Price includes tray deck, valves, bubble caps, risers, downcomers, and structural-steel
parts. The stainless steel designated is type 410 (Peters and Timmerhaus, Plant Design and Economics for Chemical
Engineers, 4th ed., McGraw-Hill, New York, 1991).
GENERAL REFERENCES: For an overall discussion of gas-liquid breakup
processes, see Brodkey, The Phenomena of Fluid Motions, Addison-Wesley,
Reading, Massachusetts, 1967. For a discussion of atomization devices and how
they work, see Masters, Spray Drying Handbook, 5th ed., Wiley, New York,
1991; and Lefebvre, Atomization and Sprays, Hemisphere, New York, 1989. A
beautifully illustrated older source is Dombrowski and Munday, Biochemical
and Biological Engineering Science, vol. 2, Academic Press, London, 1968, pp.
209–320. Steinmeyer [Chem. Engr. Prog., 91(7), 72–80 (1995)] built on Hinze’s
work with turbulence and showed that several atomization processes follow the
common theme of breakup of large droplets due to turbulence in the gas phase.
Turbulence in turn correlates with power dissipation per unit mass. In the text
below, correlations referring to power/mass are taken from this source. For a
survey on fog formation, see Amelin, Theory of Fog Formation, Israel Program
for Scientific Translations, Jerusalem, 1967.
PHASE DISPERSION
Cost of Column The cost of the vessel, including heads,
skirt, nozzles, and ladderways, is usually estimated on the basis
of weight. Figure 14-82 provides early 1990 cost data for the
shell and heads, and Fig. 14-83 provides 1990 cost data for
connections. For very approximate estimates of complete
columns, including internals, Fig. 14-84 may be used. As for
Figs. 14-82 and 14-83, the cost index is 904.
BASICS OF INTERFACIAL CONTACTORS
Steady-State Systems: Bubbles and Droplets Bubbles are
made by injecting vapor below the liquid surface. In contrast,
droplets are commonly made by atomizing nozzles that inject liquid
into a vapor. Bubble and droplet systems are fundamentally different,
mainly because of the enormous difference in density of the
injected phase. There are situations where each is preferred. Bubble
systems tend to have much higher interfacial area as shown by
Example 16 contrasted with Examples 14 and 15. Because of their
higher area, bubble systems will usually give a closer approach to
equilibrium.