Packed-Type Distillation Columns

The separation operation called distillation utihzes vapor and hquid phases at essentially the same temperature and pressure for the coexisting zones. Various lands of devices such as r andom or sti uctui ed packings and plates or tr ays are used to bring the two phases into intimate contact. Trays are stacked one above the other and enclosed in a cyhndrical shell to form a column. Pacldngs are also generally contained in a cyhndrical shell between hold-down and support plates. A typical tray-type distillation column plus major external accessories is shown schematically in Fig. 13-1. 

Hufton, J. R, J. L. Bravo, andj. R. Fair, Scale-up of Laboratory Data for Distillation Columns Containing Corrugated Metal-type Structured Packing, Ind. and Eng. Chem. Res., American Chem. Soc., V. 27, No. 11 (1988) p. 2096. 

The chemical engineering undergraduate spends most of his time sizing equipment. Usually in the problems assigned the type of equipment to be used is specified. For a distillation column the student would be told whether it is a bubble cap, a sieve plate, a valve tray, a packed column, or something else, and then asked to size it for a desired separation. In other cases he would be given the size of the specific equipment and asked to determine what the output would be for a given input. 

Continuous benzene alkylation was conducted in a reactive distillation column of the type illustrated in Figure 1. The process unit comprises the following principal elements a double column of solid catalyst 32, packing columns above and below the catalyst bed, a liquid reboiler 42 fitted with a liquid bottoms product takeoff 44, a condenser 21 fitted with a water collection and takeoff, and a feed inlet... 

Unfortunately, the fractionating column you usually get is not a bubble-plate type. You have an open tube that you fill with column packing (see Class 3 Fractional Distillation ) and noplates. The distillations up this type of column are not discreet, and the question of where one plate begins and another ends is meaningless. Yet, if you use this type of column, you do get a better separation than if you used no column at all. It s as if you had a column with some bubble-plates. And if your distilling column separates a mixture as well as a bubble-plate column with two real plates, you must have a column with two theoretical plates. 

High-purity water for special applications is obtained by distillation or by ion exchange, the exchange of one type of ion in a solution by another. In ion exchange, water passes through a column packed with a material such as zeolite, an aluminosilicate with a very open structure that can capture ions such as Mg2+ and Ca2+ and exchange them for H+ ions (see Box 13.4). 

Reactive absorption can be realized in a variety of equipment types, e.g., in him absorbers, plate columns, packed units, or bubble columns. This process is characterized by independent how of both phases, which is different from distillation and permits both cocurrent (downflow and uphow) and countercurrent regimes. 

The height of a distillation column depends on the feed conditions, the product purity specifications and the extent of separation through the vapour-liquid equilibrium relationship, but also on the type of tray or packing used in the column as this affects the rate of separation. Column vendors will normally provide information on tray or packing efficiencies.9,10... 

The contents of the three receivers are combined and distilled at atmospheric pressure through a 15-cm. indented Claisen-type still head the condenser is cooled with ice water, and the receiver is immersed in an ice bath. The fraction boiling at 25-55°, wt. 170-190 g., is redistilled through a 60-cm. column packed with glass helices or a column of similar efficiency to give 150-170 g. (63-71%) of 1,4-pentadiene, b.p. 26-27.5°/760 mm., 1.3861-1.3871 (Note 5). 

A typical gas-distillation column is shown in Fig. 3-16. The column itself is a small-diameter tube, usually on the order of 6 mm inside diameter, which contains the packing. The Heli-Grid type of pack-... 

The laboratory setup used to study this concept is shown in Figure 71. The distillation column, 30 mm I.D., consisted of a tray section in the bottom and four packed sections, each of the latter loaded with nine cartridges of type SULZER EX. The column was energized by an oil-heated falling film evaporator featuring a hermetic circulation pump. The distillate of the extractive distillation column of chapter 16.6.1 was introduced below the two uppermost SULZER columns, while hexane was introduced one SULZER section below the feed inlet. Between the bottom tray section and the lowermost SULZER section, the diketones were withdrawn as a vapor. 

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