Bubble-cap contactors

Bubble cap contactors are the most common The minimum diameter can be determined using the equation derived for gas separation in vertical separators (Volume 1, Chapter 4). This is ... 

Examples 3 and 4 presented in the following illustrate methods for estimating pressure drop with bubble-cap contactors and with sieve-tray contactors. The examples also give information as to typical design conditions for the two types of contactors. 

Distillation towers feed-tray location for, 10 optimum reflux ratio for, 371-376 specifications for, 16 (See also Bubble-cap contactors, Packed towers. Sieve trays, and Valve trays) Distribution costs, 194, 196, 207, 211 Distribution in statistical analyses, 745-746 Dividends, tax exemptions for, 259 Documentation, 137-149,452-476 Double-entry bookkeeping, 143-144 Downcomers in tray columns, 684-686 Drives, cost of 532-533 Dryers, cost of 713-716... 

Fnr stripping service, as in a glycol or amine contactor (see Chapt 7 a bubble cap trays are the most common. In recent years, there has b growing movement toward crimped sheet structured packing. Improved vapor and liquid distributor design in conjunction with struc-... 

Cross-sectional view of finite-stage contactor tower in operation showing an example of a sieve tray, a valve tray, and a bubble-cap tray. 

Many modifications of the three types of contactors just discussed have been developed in an effort to reduce costs, reduce pressure drop, equalize vapor flow through each contactor, increase plate efficiencies, or, in general, improve the operating performance of the tower. An example of this for modification of bubble-cap towers is the old Uniflux tray originally developed by Socony-Vacuum, which consisted of a series of interlocking S-shaped sections which were assembled in the form of tunnel caps with slot outlets on one side only. Segmental downcomers, similar to the downcomers in conventional bubble-cap columns, were provided. The vapors issued from the Uniflux caps in... 

Comparison of column efficiency for bubble-cap, sieve, and valve finite-stage contactors. 

For standard types of finite-stage contactor columns operated in the range of allowable velocities where the overall column efficiencies are essentially constant, O Connell has correlated efficiency data on the basis of liquid viscosity and relative volatility (or gas solubility). The results for fractionators and absorbers are presented in Fig. 16-9. This correlation is based, primarily, on experimental data obtained with bubble-cap columns having a liquid path of less than 5 ft and operated at a reflux ratio near the minimum value. Figure 16-9 is adequate for design estimates with most types of commercial equipment and... 

A simplified empirical equation for finite-stage contactor columns operating on petroleum and similar hydrocarbons has been presented by Drickamer and Bradford Their results are based on plant tests with 54 refinery columns used for distillation or absorption of hydrocarbons. The columns were of the standard bubble-cap or perforated-plate type operated under typical refinery conditions. The results were correlated on the basis of the single variable, liquid viscosity, to give... 

PRESSURE DROP THROUGH THE CONTACTOR ASSEMBLY. Causes for pressure drop through the contactor assembly are shown in Fig. 16-10 for bubble caps as (1) contraction, (2) friction in riser, (3) reversal of flow direction, and (4) friction in annular space. Similarly, Fig. 16-11 shows for sieve trays that this cause for pressure drop is (1) contraction and (2) friction in the sieve hole. The total pressure drop due to the preceding causes is primarily a function of the kinetic head. The pressure drop as feet of liquid equivalent to one kinetic head is... 

The postscript to this story is that at least one of the large new glycol distillation columns built in the last two years has (supposedly obsolete) bubble caps. The plant manager s reluctance to experiment with new designs is understandable. There are a large number of potentially unpleasant operating problems that can make life difficult for him, and, at one time or another, he has probably seen them all. Packed column vapor-liquid contactors can ... 

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