Columns perforated Plate

Fig. 12. Unagitated column extractors (a) spray column (b) packed column and (c) perforated-plate column.

Eig. 14. Regions of operation of a pulsed, perforated-plate column (141). 

The first differential centrifugal extractor to be used in industry was the PodbieHiiak extractor which was introduced in the 1950s (209,210) and can be regarded as a perforated-plate column wrapped around a rotor shaft. Rotation creates a centrifugal force which results in a great reduction in the equivalent height and contact time that would be needed in a conventional perforated-plate column. 

Direct Scale-Up of Laboratory Distillation Ljficiency Measurements It has been found by Fair, Null, and Bolles [Ind. Eng. Chem. Process Des. Dev., 22, 53 (1983)] that efficiency measurements in 25- and 50-mm (1- and 2-in-) diameter laboratory Oldersbaw columns closely approach tbe point efficiencies [Eq. (14-129)] measured in large sieve-plate columns. A representative comparison of scales of operation is shown in Fig. 14-37. Note that in order to achieve agreement between efficiencies it is necessaiy to ensure that (1) tbe systems being distilled are tbe same, (2) comparison is made at tbe same relative approach to tbe flood point, (3) operation is at total reflux, and (4) a standard Oldersbaw device (a small perforated-plate column with downcomers) is used in tbe laboratoiy experimentation. Fair et al. made careful comparisons for several systems, utibzing as large-scale information tbe published efficiency studies of Fractionation Research, Inc. 

FIG. IS-S Pulsed columns a) Perforated-plate column with pump pulse generator, (h) Packed column with air pulser. 

A small perforated-plate column of conventional design was pulsed by Goldberger and Benenati [Jnd. Eng. Chem., 51, 641 (1959)] with marked improvement in mass-transfer rates. 

Two types of contractors will be utilized a perforated-plate column for S i and a packed column for Sj. The basic design and cost data that should be employed in this problem are given by El-Halwagi and Manousiouthakis (Chem. Eng. Sci., 45(9), p. 2831, 1990a). 

Column diameter for a particular service is a function of the physical properties of the vapor and liquid at the tray conditions, efficiency and capacity characteristics of the contacting mechanism (bubble trays, sieve trays, etc.) as represented by velocity effects including entrainment, and the pressure of the operation. Unfortunately the interrelationship of these is not clearly understood. Therefore, diameters are determined by relations correlated by empirical factors. The factors influencing bubble cap and similar devices, sieve tray and perforated plate columns are somewhat different. 

Stewart, W. S., Heat and Mass Transfer Coefficients for the System Air-Water in a Perforated Plate Column, thesis presented in partial fulfillment of Master s Degree in chemical engineering, Louisiana State University (1958). 

For stirred tanks with hold-ups up to 0.35 the constant K = 0.024 ( 1For reciprocating-plate extraction columns K = 0.I8, while for pulsed perforated-plate columns AT = 0.18 Kirk-Othmer Encyclopedia of Technology, 1978-1984). 

Oldershaw, C. F. (1941) Ind. Eng. Chem. (Anal, ed.) 13, 265. Perforated plate columns for analytical batch distillations. 

Perforate basket centrifuges, 16 660 operation, 5 529, 543-545 Perforated bowl centrifuge, theory of performance, 5 515 Perforated-drum dryers, 9 120 Perforated-plate columns, 10 772-774 Perforated plates, 11 810 Performance. See also Filter performance of BJTs, 22 248-249 of FETs, 22 165... 

Gravity Group A Spray column Packed column Group B Perforated plate column... 

Fig. 12. Pulse columns (a) liquid-pulsed, perforated-plate column (6) air-pulsed, packed column (T2).

Fig. 13. Flow characteristics of pulsed perforated-plate columns (S6).

Oldershaw column. An all-glass perforated-plate column. The plates are sealed into a tube, each plate being equipped with a baffle to direct the flow of reflux liquid, and a raised outlet which maintains a definite liquid level on the plate and also serves as a drain on to the next lower plate [see Oldershaw Ind Eng Chem (Anal Ed) 11 265 1941]. 

Spray columns Packed columns Perforated-plate columns... 

Perforated-plate columns Sieve-plate columns with downcomer Varied-perforation plate... 

Perforated-plate columns are semistage in operation. They are reasonably flexible and efficient. A 7-ft-diameter, 80-ft-high perforated-plate column used for extraction of aromatics was reported to have the equivalent of 10 theoretical stages. Because of the simplicity and low cost of packed and perforated-plate columns, they are widely used in industry despite their low efficiency, particularly for processes requiring few theoretical stages and for corrosive systems where absence of mechanical moving parts... 

Pulsed perforated-plate columns (Fig. 12) are fitted with horizontal perforated plates or sieve plates which occupy the entire cross section of the column. The total free area of... 

FIGURE 12 Pulsed-perforated-plate column. (Reprinted courtesy of ERIES, France.)... 

In 1935, Van Dijck proposed that the extraction efficiency of a perforated-plate column could be improved by either pulsing the liquid contents of the column or by reciprocating the plates. The latter idea was relatively little exploited until the late 1950s, when Karr reported data on a 3-in.-diameter, open-type, perforated reciprocating-plate column. The column was further developed by Karr and Lo by employing baffles. 

Domenech and Enjalbert (1974) carried out a series of experimental tests in a laboratory batch distillation column. A binary mixture of Cyclohexane and Toluene was considered for the purpose. The experimental equipment used was a perforated plate column, with 4 trays and a 60 litre reboiler heated with a heat transfer coefficient of 3 kw. The experimental results obtained by Domenech and Enjalbert together with column input data are presented in Table 4.5. 

Mechanical reciprocation Karr Column Pulsed Packed Column Pulsed Perforated Plate Column... 

In the procedure originally planned for the operation of industrial plants employing this process, the reaction is carried out in a perforated plate column containing the catalyst, at between 110 and 130°C, under 3 to 4.10 Pa absolute. The circulation gases (fresh and recycled ethylene, recycled oxygen) and acetic add are introduced at the base of the reactor. Make-up oxygen is introduced, directly into the solution. The stream leaving the reactor is cooled and partly condensed ... 

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