Tower Roundness

Neither the tray nor the tower is a perfect circle. Usually, both tower and tray are round to within 0.5 to 1 percent of their respective nominal diameters (38, 86, 192). The normal practice is to allow a clearance of about 1 in between the tray and the shell (86, 138). More detailed guidelines are presented elsewhere (138). 

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An elegant joint can be obtained by heating the joint strongly all round, and as it thickens moving the tower tube up then the whole is blown out and the tower tube is moved down, so that a smooth joint is made. This procedure resembles the joining of two tubes by Method 1. 

We felt our way round Gainsborough in the deepest dark, and when a hungry dawn came, we saw first the towers of Lincoln Ca-... 

Perform the preliminary exercises and then project the Table Round. Take your place at your siege. Observe that you are clothed in a hooded robe of deep blue-violet, the indigo color of Akasha. The hood is a symbol of impersonality, the necessary attitude of mind for this work. There are silver sandals, the magical tool of Yesod, upon your feet, for you are walking the shining Paths of the Tree. This robe and these sandals should be your usual inner attire when working within the Tower. 

Enter the tower, pass around the central column, approach the low entrance enshrouded in mist, and step again into the Hall of the Round Table. Go straight to the chapel and there give thanks before the altar. Return to the Great Hall and sit at the table. There, in the harmonizing... 

If an ammonia cylinder is not available the gas is obtained by heating concentrated ammonia solution in a round-bottomed flask over a screened flame. The gas must be dried by passage through a tower containing potassium hydroxide and good quicklime. The amount of ammonia required is calculated as follows (small excess). 

In a 50-mL two-necked round-bottomed flask, fitted with a Teflon septum, a Teflon adapter with a Teflon outlet tube attached to a soda lime tower, and a Teflon O-ring to hold the Teflon tuhe, was placed a solution of ( + )-2,10-(3,3-dichlorocamphorsultam) (3.0 g, 10.6 mmol) in CHCI3 (50 mL). To this solution was added of NaF (2.1 g, 50 mmol), dried overnight under high vacuum. The reaction flask was cooled... 

The ammonium nitrate solution (from the neutralizer) is evaporated to ca. 96% concentration in the steam heated vacuum evaporator. The concentrated solution is sprayed into the top of the prilling tower, where it falls through an upward flow of air supplied by blowers at the base of the tower. During its fall it is cooled and solidifies to round pellets or prills of the desired size. 

In a 200-cc. round bottom flask is placed 80 g. (0.71 mole) of crude 2-furancarboxylic acid (Org. Syn. 6, 44) (usually about 95 per cent pure). To the neck of the flask is fitted an upright tube 2.5 cm. in diameter and 15 cm. long, with a side arm of the same diameter leading out about 2 cm. from the top of the tube. This side arm is extended into the bottom of an efficient (25-cm.) soda-lime tower (Note 1) immersed in a water bath held at 40° to prevent condensation of the furan. From the top of the soda-lime tower an outlet tube (0.5 cm. in diameter) is extended to the top of an upright water condenser, to the lower end of which is attached a receiving flask surrounded by ice and salt (Note 2). 

However, in some reactions a very high grade of anhydrous aluminium chloride may be required. This is conveniently prepared by placing the crushed pellets in a suitably sized round-bottomed flask fitted with a simple distillation bend to which is attached a two-necked round-bottomed receiver flask the second outlet is connected to a water pump via a drying tower similar to that shown in Fig. 4.2 and filled with granular calcium chloride. The distillation flask is heated cautiously with a brush flame and the aluminium chloride sublimes under reduced pressure. It is inadvisable to use an oil immersion rotary pump because of possible corrosion damage even with suitably placed protection traps. 

FIG. 14-70 Flashing feed and vapor distributors, (a) Bare nozzle, (b) Rounded V baffle, (c) Peripheral flash box—the box extends right around the tower wall, with the collected liquid descending via downpipes to a liquid distributor below, (d) Gallery distributor—the feed enters the gallery area (upper plate). (Parts a-c, courtesy of Sulzer Chemtech part d, courtesy of Koch-Glitsch LP.)... 

Packed-tower efficiency and turndown are strongly dependent on the quality of initial liquid distribution. Uneven distribution may cause local variations in the liquid/gas ratio, localized pinch conditions, and reduced vapor-liquid contact. Figure 14 shows two common liquid distributor types, the ladder type (shown as the top distributor) and the orifice type (shown as the redistributor). The ladder type is a horizontal header of pipes, which are perforated on the underside. The orifice type is a flat perforated plate equipped with round or rectangular risers for gas passage. Other common types of distributors are a header equipped with spray nozzles (spray distributor) and a header of horizontal channels, with V notches cut in the vertical walls of the channels (notched-trough distributor). 

The flood-point and the maximum pressure drop criteria gave comparable tower diameters. The more conservative of the two criteria gives diameters of 5.50 and 6.12 for the top and bottom section of the tower, respectively. As the diameters for the top and bottom sections are not much different, it is attractive to use uniform column diameter. The decision of whether to make the top and bottom section diameters the same is based on the same criterion as for tray columns (Sec. 6.5.3). The preliminary column diameter is the larger for the two column sections, i.e., 6.12 ft. This diameter is normally rounded to the next nearest half foot, but in this example it is rounded only to the next nearest quarter foot. A diameter of 6.12 is far closer to 6 ft than to 6.5 ft. Column diameter is relatively small, and three excessive inches substantially increase the costs. The column is operated at high pressure, and high-pressure shells are expensive. Therefore, the preliminary column diameter is 6 ft 3 in. 

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