Packed columns structured packings

Fig. 10 Molecular arrangement in the crystal packing a and ID column structure b all uncoordinated atoms in axial ligands are omitted in 14...

The older tall oil distillation columns used bubble cap trays. In new columns, structured packing is preferred. Because of the low pressure drop of structured packing, steam injection is no longer necessary. The low liquid holdup of this packing minimizes the reactions of the fatty and resin acids. A specific distillation sequence for vacuum columns using structured packing of Sulzer has been described (26). Depitching is carried out at a vacuum of... 

From the above MC simulation results, a suppositional concentric square column structure is constructed, which is not observed in MC simulation (Yu et al., 2007a) but can be considered as a basic block of the CMSC structure. We plot the same four architectures together forming a close-packed structure in Figure 37. Under curved confinements, the topological CMSC structure can be considered as the cross-sectional concentric circle that truncates the four close-packed square columns with the exterior radii Rex, and the center is at the common corner of the four squares. Among the four square columns, the phase structures of... 

Since the mobility in a packed capillary is dependent on both the zeta potential and the column structure, it is important to take into account of the column architecture when EOF mobility is evaluated. An expression for calculating the actual interstitial mobility for a solute in a packed column is [31,32]... 

The catalytic distillation section uses a zeolite catalyst that is packaged into specially engineered bales. The catalyst bales function similarly as typical column structured packing and are designed to optimize both the distillation and the chemical reaction processes that occur in this portion of the alkylator. ... 

Many considerations influence the choice between a packed column and a trayed column for a particular application, foremost among which are economics and performance versatility. The decision involves many variables and is best handled on a case-by-case basis. Example 15.3 compares the performance of the same column structure, using either trays or packing. 

Stationary Packed column Structure Polarity Applications... 

Figure 5-15. Relative deviation 8(Ap/H) of experimental data for determination of pressure drop (Ap/H)exp up to flooding point acc. to Eqs. (5-9) and (5-10), valid for tube columns, structured and stacked packings. No. of system see Table 2-2. Test conditions see Table 5-la-c...

D. Rectification in vertical wetted wall column with turbulent vapor flow, Johnstone and Pigford correlation =0.0.328(Wi) Wi P>vP 3000 < NL < 40,000, 0.5 < Ns. < 3 N=, v,.gi = gas velocity relative to R. liquid film = — in film -1 2 " [E] Use logarithmic mean driving force at two ends of column. Based on four systems with gas-side resistance only, = logarithmic mean partial pressure of nondiffusing species B in binary mixture. p = total pressure Modified form is used for structured packings (See Table 5-28-H). 

Refitting of a tray-type column is desired to increase loading, increase efficiency, and/or decrease pressure drop. Structured packing is pariicularly applicable in this case. 

Efficiency data for a representative structured packing at two column diameters are shown in Fig. 14-74. The Max-Pak packing has a surface area of 246 m /m (7.5 ft /fE). The same test mixture (cyclo-hexane//i-heptane) and operating pressure was used for both tests. It would appear that column diameter does not have an influence in this range of values (0.43 to 1.2 m). 

FIG. 14-74 HETP values for Max-Pak structured packing,. 35 kPa (5 psia), two column diameters. Cyclohexane/n-heptane system, total reflux. For 0.4.3 m (1.4 ft) column perforated pipe distributor, 400 streams/m2, 3.05 m (10 ft) bed height. For 1.2 m (4.0 ft) column tubed drip pan distributor, 100 streams/m ,. 3.7 m (12 ft) bed height. Smaller column data. University of Texas/Austin Larger column data. Fractionation Research, Inc. To convert (ft/s)(lb/ft ) to (m/s)(kg/m ) , multiply by 1.2199. (Couiiesy Jaeger Troducts, Inc., Housion, Texas.)... 

Packed-Bed Fixed-Film Systems These systems were originaUy termed anaerobic trickhng filters because the first systems were submerged columns filled with stones run under anaerobic conditions (Fig. 25-57). A wide variety of packed media is now used ranging in size from graniiles 40 mesh to 7.5-cm (3—in) stones. Many systems use open structure plastic packing similar to that used in aerobic trickhng filters. 

Once packing heights are determined in other sections from HETP (distillation) or Koa (absorption), the height allowances for the internals (from Figure 1) can be added to determine the overall column height. Column diameter is determined in sections on capacity and pressure drop for the selected packing (random dumped or structured). 

Problem A structured packing vacuum tower had too much heavy key in a vapor side-draw between the feed and the column bottom. The side-draw heavy key concentration was several times the design value. 

Because of the three-dimensional void structure of a packed column, the exact form of the velocity profile is not clearly defined as in the microtubular... 

Figure 9-6Y. Panapak formed/structured packing for a 6-ft diameter column (original design). Used by permission of Packed Column Corp.

Figure 9-8G. Koch/Sulzer trough distributor (MDP), for medium to large diameter columns for structured packing (patented), one of several designs available. Used by permission of Koch Engineering Co., Inc., Bull. KS-6.

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