Random packings plastic

Table 6 Packing factors random packing, plastic ...

Structured packings are produced by a number of manufacturers. The basic construction and performance of the various proprietary types available are similar. They are available in metal, plastics and stoneware. The advantage of structured packings over random packing is their low HETP (typically less than 0.5 m) and low pressure drop (around 100 Pa/m). They are being increasingly used in the following applications ... 

Fib er-Bed Scrubbers Fibrous-bed structures are sometimes used as gas-liquid contactors, with cocurrent flow of the gas and liquid streams. In such contactors, both scrubbing (particle deposition on droplets) and filtration (particle deposition on fibers) may take place. If only mists are to be collected, small fibers may be used, but if solid particles are present, the use of fiber beds is limited by the tendency of the beds to plug. For dust-collection service, the fiber bed must be composed of coarse fibers and have a high void fraction, so as to minimize the tendency to plug. The fiber bed may be made from metal or plastic fibers in the form of knitted structures, multiple layers of screens, or random-packed fibers. However, the bed must have sufficient dimensional stability so that it will not be compacted during operation. 

In comparison with tray towers, packed towers are suited to small diameters (24 in. or less), whenever low pressure is desirable, whenever low holdup is necessary, and whenever plastic or ceramic construction is required. Applications unfavorable to packings are large diameter towers, especially those with low liquid and high vapor rates, because of problems with liquid distribution, and whenever high turndown is required. In large towers, random packing may cost more than twice as much as sieve or valve trays. 

Pressure drop has been reported for a number of rotor internals, including corrugated structured packing (28), foam metal (26,40,42), rectangular and elliptical cylinder plastic grains randomly packed (41), wire screen (43), and glass beads (17). In spite of the variation in porosity from 0.38 to 0.95 and in volumetric surface area from 500 to 4000 m2/m3, all of these studies showed similarities of increased pressure drop as rotor speed increased and gas rates increased. 

Figure 8.2 (Continued) Second-generetion random packings, (cl Super Intalox seddie, plastic (d) Pall ring, metal, (Courtesy of Norton Company.)...

Figure 8.4 Third-generation plastic random packing , to) Cascade MiniRing (CMR ) (6) Hiflow ring. (Pori a, courtesy of Glitsch, Inc. port b, courtesy of Rauschert Industries, Inc.)...

Figure 8.4 (Continued) Third-sene ration plastic random packings. (c) Jaeger Tri-Packs (Hackette ) (d) NOR-PAC (NSW rings). (Part c, courtesy of Jaeger Products, Inc. part d, courtesy of Nutter Engineering Corp.l...

Ftgurt M (Continued) Thl rd gen era lion plastic random packings, (e) Intalox Snowflake19 packing Norton Company ports f and g courtesy of Lantec. Inc.)... 

Depth of plastic random packings may be limited by the deformability of the packing elements to 10-15 ft. For metal random packings, this height can be 20-25 ft. For both random and structured packings, the height between redistributors is limited to 20-25 ft. because of the tendency of the phases to maldistribute. 

The first of the widely used random packings were Raschig rings which are hollow cylinders of ceramics, plastics, or metal. They were an economical replacement for the crushed rock often used then. Because of their simplicity and their early introduction, Raschig rings have been investigated thoroughly and many data of their performance have been obtained which are still useful, for... 

FIG. 14-48 Common first- and second-generation random packings, a) Raschig ring (metal, plastic, ceramic), (h) Berl saddle (ceramic), (c) Pall ring (metal), ((i) Pall ring (plastic), (e) Intalox saddle (ceramic). (/) Super Intalox saddle (plastic). (Parts d,f courtesy of Koch-Glitsch LP.)... 

Plastic random packing Super INTALOX Saddles 1 204 0.896... 

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