Types of Random Packings

The second generation (late 1950s to the early 1970s) produced two 

The third generation (the mid 1970s until present) has produced a multitude of popular geometries, most of which evolved from the Pah ring and Intalox saddle. 

Berl saddles (Fig. 8.1 di. These are the original type of saddle padcing. 

Intalox saddles (Fig. 8.2a). Developed by the Norton Clompany, they superseded the Berl saddles. The shape of the Berl saddle was modi-in the Intalox so that adjacent elements do not blank off any 1 

Hgure 8.1 First-generation random packings, (a) Raschig rii, metal (6) Lessing ring, metal c) Berl saddle, ceramic. 

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Common types of random packings are shown in Fig. 15. The packings shown in Fig. 15a-c have been largely superseded by the packings shown in Fig. 15d-h. 

FIGURE 15 Common types of random packings (Parts e and f, courtesy of Norton Co. part g, courtesy of Glitsch, Inc. part h, courtesy of Nutter Engineering Corp.)... 

Figure 3-11 shows the product of the volumetric mass transfer coefficient fig and effective volume specific surface for mass transfer, as a function of gas and liquid loads for different types of random packings, found by empirical means. 

Pulse colunms containing conventional types of random packing have been found to have similar theoretical stage heights to those with sieve-... 

Finally, it can be noted that the liquid hold-up hL for any types of random packing elements and type Y structured packings can be calculated using Mersmann and Deixler s [44] model as well as the modified method by Berner and KaHs [12] with an accuracy of 20-25%. 

Fig. 10.2-2. Six types of random packing. These packings aim to resolve the conflicting goals of fast flow and large interfacial areas.

The rigorous column models allow the design engineer to carry out tray sizing and hydraulics calculations for the basic types of distillation trays and for some types of random and structured packing. Different commercial simulators use different tray sizing correlations, but they all follow a method similar to that described in Chapter 11. 

In this equation AT is a constant, characteristic of packing type and size. Pressure drops through beds of random packings have been correlated by these equations,21-23 but it is not yet possible to point toward a particular piece of work that gives reliable results for the foil range of possible packings,... 

Figure 7. Various Types of Random Fractionation Packing (Drawing courtesy ExxonMobil Research and Engineering)...

The hydraulic operation of structured packings with countercurrent gas and liquid flows is somewhat different than that of random dumped packings. The wire-gauze type is wetted by capillary action, so that the entire geometric surface area becomes available for mass transfer at low liquid flow rates. Thus, Sulzer BX packing was found to have 2 A times the static liquid holdup of Flexipac 2 or Gempak 2A sheet metal types of structured packings [14]. However, once the surface is completely wetted, capillary action has only a small effect as the liquid rate increases. 

It has been well established that the efficiency of random packings is significandy affected by the quality of liquid distribution onto the packed bed. As was true when saddle-type packings first were developed, initially structured packings were assumed to be able to rectify the initial inferior liquid distribution quality. More recent work has shown that liquid distribution quality also is critical to achieving high mass transfer efficiency with structured packings [9]. 

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