Cylindrical column

Equipment Absorption, stripping, and distiUation operations are usually carried out in vertical, cylindrical columns or towers in which devices such as plates or packing elements are placed. The gas and liquid normally flow countercurrently, and the devices serve to provide the contacting and development of interfacial surface through which mass transfer takes place. Background material on this mass transfer process is given in Sec.. 5. 

For a smooth cylindrical column or stack the following semi-empirical equation can be used to estimate the wind pressure ... 

In a multiple-hearth roaster, the concentrate drops through a series of nine or more hearths stacked inside a brick-lined cylindrical column. As the feed concentrate drops through the furnace, it is first dried by the hot gases passing through the hearths and then oxidized to produce calcine. Multiple hearth roasters are unpressurized and operate at 700°C (1300°F). 

An impurity in a water stream at a very small concentration is to be removed in a charcoal trickle bed filter. The filter is in a cylindrical column that is 2 ft in diameter, and the bed is 4 ft deep. The water is kept at a level that is 2 ft above the top of the bed, and it trickles through by gravity flow. If the charcoal particles have a geometric surface area to volume ratio of 48 in.-1 and they... 

The Samuel-Magee model can be extended to a-particle tracks, considered as cylindrical columns formed by excessive spur overlap due to high LET. To a good approximation, the length I of the cylinder remains constant while its radius grows by diffusion. In this geometry, the normalized radical distribution is given by... 

The vertical cylindrical column provides, in a compact form and with the minimum of ground requirements, a large number of separate stages of vaporisation and condensation. In this chapter the basic problems of design are considered and it may be seen that not only the physical and chemical properties, but also the fluid dynamics inside the unit, determine the number of stages required and the overall layout of the unit. 

These are simple cylindrical columns provided with baffles to direct the flow of the dispersed phase, as shown in Figure 13.29. The efficiency of each plate is very low, though since the baffles can be positioned very close together at 75-150 mm, it is possible to obtain several theoretical stages in a reasonable height. 

An adsorption unit is to be designed to dry air using silica gel. A moving-bed design is considered in which silica gel moves down a cylindrical column in plug flow while air flows up the column. Air enters the unit at the rate of 0.129 kg of dry air/m2s and with a humidity of 0.00267 kg water/kg dry air. It leaves essentially bone dry. There is equilibrium between air and gel at the entrance to and the exit from the adsorption zone. Experiments were carried out to find the relative resistances of the external gas film and pellet diffusion. Referred to a driving force expressed as mass ratios then ... 

An important measure concerning column characterization in LC is the column permeability, which represents the capacity of the support to transport the mobile phase as consequence of a pressure drop occurring over the column. In other words, the permeability of a column determines the required pressure to achieve the desired flow rate. The linear flow velocity (u) across an empty cylindrical column is given by... 

The results in Table 9.2 apply when no end effects are present. Sutterby (S7) determined simultaneous wall and end correction factors for the creeping flow range. His correlations are shown in Fig. 9.3 where the cylindrical column has closed ends a distance apart and the center of the spherical particle is distance Z from one end of the tube. The curve for D/L = 1.0 and Z/L = 1/2 is... 

A plot of all the data as Uj/Ujr o = (where is the terminal velocity which the drop or bubble would have in an infinite container, as taken or extrapolated from the authors own data) versus Re shows that, as for rigid spheres in cylindrical columns, the terminal velocity ratio deviates further from unity as z increases and as Re or Nq decreases. In fact, the curves in Fig. 9.5 may be taken over and used directly for the prediction of for... 

While all the data discussed in this section are for large bubbles, it is reasonable to expect the results to apply also to large liquid drops for which Eo > 40. For drops and bubbles in columns of noncircular cross section the results derived for cylindrical columns may be used with D replaced by the... 

Figure 5.4 Self-assembly of wedge-shaped molecules (modified from Zeng et al 2004). (a) Dendrons with fewer tethered chains adopt a flat slice-like shape (X is a weakly binding group), (b) The slices stack up and form cylindrical columns, which assemble on a two-dimensional hexagonal columnar (Col ) lattice (c). (d) Dendrons with more end-chains assume a conical shape, (e) The cones assemble into spheres, which pack on three different three-dimensional lattices (f) with different symmetries.

A deton wave once formed in an expl has a tendency to die out or "fade if the diam of the expl is below a certain min (called boundary diam). It may be detd by using a cast cone detonated from the base. The diam of the cone at which the wave is extinguished is a measure of the fading properties of the expl. The observation may be made photographically by means of a rotating mirror camera. The value so obtd tends to be less than the value from cylindrical columns of expl. See Vol 4, p D223 Ref D.W. Woodheath R. Wilson, Nature 167, 565(1951)... 

A very long cylindrical column of expl was initiated at one end and the time for the explosion to travel to the other end was recorded hy Le Boulange Chronograph. It is still used to measure the muzzle vel of projectiles. This apparatus has been replaced by the Mettagang Recorder, Method of Dautriche and the Optical Electronic Chronographs for measuring velocities of deton of expls (See also Chronographs)... 

Fixed-Bed Adsorption The adsorbent can be packed in a cylindrical column (or tube in small scale) and the diluent passed through for the selective adsorption of the solute of interest. It is one of the most common methods for adsorption in both laboratory or industrial scale separations. 

The onset of powder motion in a hopper is due to stress failure in powders. Hence, the study of a hopper flow is closely related to the understanding of stress distribution in a hopper. The cross-sectional averaged stress distribution of solids in a cylindrical column was first studied by Janssen (1895). Walker (1966) and Walters (1973) extended Janssen s analysis to conical hoppers. The local distributions of static stresses of powders can only be obtained by solving the equations of equilibrium. From stress analyses and suitable failure criteria, the rupture locations in granular materials can be predicted. As a result, the flowability of granular materials in a hopper depends on the internal stress distributions determined by the geometry of the hopper and the material properties of the solids. 

In practice, emulsification requires even more energy than that calculated in the above example, since deformation of large drops is needed before smaller drops can pinch off (Figure 3.4). In laminar flow this deformation is produced by viscous forces exerted by the surrounding liquid. If a stream of liquid is injected with low turbulence into another, immiscible liquid the cylindrical column of liquid will eventually become unstable and break up into droplets (Figure 3.4a). Under high turbulence the breakdown occurs sooner and produces smaller droplets (Figure... 

The cumene used was Eastman pure grade or Phillips pure grade, which was further purified to remove polar inhibitors, mostly cumene hydroperoxide. This was accomplished at room temperature by passing the cumene at a rate of 5 cc./min. through a 5- by 120-cm. cylindrical column containing alternate layers of silica gel and freshly burned clay. The alternate layers were about 5 cm. deep. 

Distillation is the dominant separation process in the petroleum and chemical industries. It is carried out continuously more often than batchwise, in large, vertical, hollow cylindrical columns (or towers). Figure 1 shows a large distillation column with its associated piping, heat exchangers, vessels, ladders, platforms, and support structures. Figure 2 shows a simple schematic representation. 

Limestone having an average diameter of 3 cm is packed in a 100-cm cylindrical column. The voids are calculated to be 34.5 percent. Air having a temperature of 320 deg C is made to flow through the column at a rate of 500 liters per sec. Determine the coefficient of heat conductivity. 

In principle, all the six-membered ferric wheels [Fe6CI6(LM l7)6] (39) are isostructural and have idealized S g-molecular symmetry. However, there are fundamental differences concerning their crystal packing. For example, all the disk-like molecules of 39a are arranged in parallel and are piled in cylindrical columns, with all the iron centers superimposed. Each column is surrounded by six parallel columns, which are alternately dislocated by 1/3 c and 2/3 c against the central one (Fig. 13). 

For the cylindrical column this approach leads to the following picture ... 

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