Bubble plate column

Much of this work was carried out using a special distilling column called a bubble-plate column (Fig. 141). Each plate really does act like a distilling flask with a very efficient column, and one distillation is really carried out on one physical plate. To calculate the number of plates (separation steps, or distillations) for a bubble-plate column, you just count them ... 

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. 

Well, all you can do is estimate that it falls at, say, a little more than half of the way along this second tie-line, eh (Point K) OK then. This column has been officially declared to have 1.6 theoretical plates. Can you have tenths of plates Not with a bubble-plate column, but certainly with any column that does not have discrete separation stages. 

The development of adsorption as a method of fractionation has been analogous to the development of distillation. In both cases the operation was originally carried out in a simple batch unit. After many years, rectification was added and close fractionation became possible. In the case of distillation this was done by adding a packed or bubble plate column to the still kettle. In the case of adsorption it involved the use of an adsorbent-packed column to obtain chromatographic separation, which gave a rectification effect. 

FIG. 15-38 Extraction rates for sieve-plate and modified bubble-plate columns. System benzoic acid-water-toluene, except where noted. To convert feet to meters, multiply by 0.3048 to convert inches to centimeters, multiply by 2.54. [Allerton, Strom, and Treybal, Trans. Am. Inst. Chem. Eng., 39y 361 (1943) Row, Kojfolt, and Withrow, ibid., 37,559 (1941) Treybal and Dumoulin, Ind. Eng. Chem., 34, 709(1942).]... 

A group of parallel-connected separating units, all fed with material of the same composition and producing partially separated product streams of the same composition, is known as a stage. Often a single unit serves as a stage, like a plate of bubble-plate column. However, in some separation methods whose units have low capacity, such as an electrolytic cell or centrifuge, it is necessary to use many units in parallel. 

The low holdup and low start-up time is another advantage of Spraypak compared with bubble-plate columns. 

A straw oil used to absorb benzene from coke oven gas is to be steam stripped in a bubble plate column at atmospheric pressure to recover the dissolved benzene. Equilibrium conditions are approximated by Henry s law such that, when the oil phase contains 10 mole% CtHt, the CuHe partial pressure above it is 5.07 kPa. The oil may be considered nonvolatile, and the operation adiabatic. The oil enters containing 8 mole% benzene, 75% of which is to be recovered. The steam leaving contains 3 mole% C6H . 

Continuously operating pilot plant wnth vapour-collision bubble-plate columns for tbe simulation of crude oil production conditions... 

Each step along the path A-B-C-D-E-F of Figure 4.3 represents a single ideal distillation. One type of fractional distillation column, the bubble-plate column, was... 

In practice the packed tower has been losing out relative to the bubble tower. The development of corrosion-resistant alloys and of bubble-plate columns made of ceramic, glass, and plastic has made it possible to rectify corrosive mixtures in such units. The development of efficient laboratory bubble-plate columns as small as 1 in. in diameter has made it possible to carry out such distillation in the laboratory, and experience has indicated that these columns give data that are... 

Phenol-Water Rectification Example. A plant using phenol as a solvent desires to rectify a mixture containing 1.0 mol per cent phenol in water. As the bottoms are to be discarded in a nearby river, they must not exceed 0.001 mol per cent phenol. A system similar to that shown in Fig. 8-6 will be employed. The overhead vapors from the bubble-plate columns to be used are condensed and cooled to 20°C. Under these conditions the condensate separates into two saturated layers. The water layer is reheated to its boiling point and refluxed to column 1, and the... 

Several investigators have published quantitative data on the amount of entrainment in bubble-plate columns. Most of their investigations have been on systems involving air and water. 

Holbrook and Baker (Ref. 16) studied entrainment in an 8-in. bubble-plate column using steam and water. Curves C are based on a portion of their data. They conclude that the plate spacing and vapor velocity were the main factors in determining the amount of entrainment and that the amount of liquid flow and slot-vapor velocity were of less importance. 

Schematic drawing of the liquid heads in a bubble-plate column.

Caustic scrubbing is one of the earlier methods used for primary cleanup (CEC, 1982a). NaOH or KOH in solution is used in a packed column or bubble plate column. Decontamination factors (DF) of 10 or more have been achieved. I2 is effectively trapped but organic... 

Desorption. The solution is stripped in a column called the actifier, which is operated at a pressure of about 2.0 to 2.5 psia. Steam is used as stripping vapor and is generated by boiling the solution in the reboiler at the base of the actifier. Because of the reduced pressure, boU-ing occurs at a temperature of about 140 F (60°C). Both wood hurdle-packed and bubble-plate columns have been employed for aerifying, hi plant B of Table 5-14, the actifier is equipped with IS stainless-steel bubblecap trays. 

At Olin-Mathieson s plant in Pasadena, Texas, 93% sulfimc acid is added to the solution withdrawn from the scrubber in a Karbate mixing tee. The mixture passes into a lead-lined, steel bubble-plate column through which air is blown. Acid-feed rate to the stripper is regulated by a controller operating on the pH of the neutralized solution. The air-sulfur dioxide mixture is forced into the drying tower of the sulfuric acid plant, and the anunonium sulfate solution is processed in an adjacent fertilizer plant. 

White, R. R., Bubble Plate Column Design, Pet. Processing February, 1947, p. 147. 

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