T f t t

Dstilling Tray Parts Valve Tray Distillation

Figure 6.2 Flow-through tray vapor passages, (a) Bubble-cap tray, (b) sieve tray <c> valve tray. (M. Van Winkle, Distillation, Copyright © 1967 by McGraw-Hill Inc., reprinted by permission.)

ment, and pressure drop. Bubble-cap trays have lower capacity and efficiency and higher entrainment and pressure drop than sieve and valve trays. Dual-flow trays show better capacity but inferior efficiency than other types.

The turndown of valve trays is much better than sieve trays, but not as good as bubble-cap trays. Bubble-cap trays are the most suitable to handle extremely low liquid rate applications [less than 2 gpm per foot of average flow width (10)].

The cost of bubble-cap trays is by far the highest. Sieve trays are the least expensive, but valve trays are only slightly more expensive.

Valve TraysRound Valve Trays

Figure 6.3 Valve trays, (a) A valve tray equipped with round, uncaged valves, (ft) A valve tray equipped with round, caged valves, (c) A valve tray equipped with rectangular valves, (cf) A valve tray containing both round, uncaged valves ana perforations. (Parts a and d nmrteny of Kiwh Knginttring Company Inc.- part h courteny ofGUtfch, Inc; part c courtesy of Nutfr Kngin—rittg)

Distillation Alcohol
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Triangular Tray Valves

Figure 6.4 Types of valve units, (a) An uncaged, round valve unit. (6j A caged, round valve unit, (c) A caged, round valve unit featuring a contoured orifice. id\ A rectangular valve unit. (<?) A fixed, round valve unit. (/) A fixed, triangular valve unit. (Parts a and e courtesy of Glitsck Inc.; parts b, c and f courtesy of Koch Engineering Company, Inc. part d courtesjy of Nutter Engineering.)

Figure 6.4 Types of valve units, (a) An uncaged, round valve unit. (6j A caged, round valve unit, (c) A caged, round valve unit featuring a contoured orifice. id\ A rectangular valve unit. (<?) A fixed, round valve unit. (/) A fixed, triangular valve unit. (Parts a and e courtesy of Glitsck Inc.; parts b, c and f courtesy of Koch Engineering Company, Inc. part d courtesjy of Nutter Engineering.)

table 6.1 Comparison of the Common Tray Types

Type

Sieve tray

Valve tray

Bubble-cap tray

Dual-flow tray

Diagram

6.1c

6.3, 6.4

0 -1

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