Packing metal

Corrosivity. Corrosivity is an important factor in the economics of distillation. Corrosion rates increase rapidly with temperature, and in distillation the separation is made at boiling temperatures. The boiling temperatures may require distillation equipment of expensive materials of constmction however, some of these corrosion-resistant materials are difficult to fabricate. For some materials, eg, ceramics (qv), random packings may be specified, and this has been a classical appHcation of packings for highly corrosive services. On the other hand, the extensive surface areas of metal packings may make these more susceptible to corrosion than plates. Again, cost may be the final arbiter (see Corrosion and corrosion control). 

T] Check of 132 data points showed average deviation 14.6% from theory. Johnstone and Pig-ford [Ref. 105] correlation (5-22-D) has exponent on Nue rounded to 0.8. Assume gauze packing is completely wet. Thus, = a, to calculate Hq and Same approach may be used generally applicable to sheet-metal packings, but they will not be completely wet and need to estimate transfer area. 

FIG. 10-97 Typical packing arrangement, using metallic packing, for high-pressure cylinders. 

For columns less than 0.6-m (2.0-ft) diameter, packings are usually cheaper than plates unless aUoy-metal packings are required. 

Figure 9-6N(b). Fleximax high performance random metal packing available in two sizes and reported by manufacturer to be a fourth generation random packing. Used by permission of Koch Engineering Co., Inc., Bull. KFM-1. 

Polished metal packings and poor wetting surfaces (some plastics, glazed porcelain, etc.)... 

Figure 9-211. Norton IMTP Packing, Efficient Capacity Correlation for random metal packing only for non-foaming systems. Norton recommends designing up to 90% of efficient capacity ...

The rod is packed with full-floating metallic packing, force-feed lubricated and vented when the gas composition requires. Vented packing is illustrated. 

PISTON RINGS are of the single-piece, snap-ring type. PISTON-ROD AND TAIL-ROD are one piece of carbon-steel, flame-hardened over packing travel area. The rod is packed with full-floating metallic packing, force-feed lubricated, and vented when the gas composition requires. Vented packing is shown. 

Full-floating metallic packing is self-adjusting. 

Cast iron is the standard material used to construct the cylindrical housing, but other materials may be used if corrosive conditions exist. The rotor is usually a continuous piece of steel that includes the shaft and is made from bar stock. Special materials can be selected for corrosive applications. Occasionally, the rotor may be a separate iron casting keyed to a shaft. On most standard air compressors, the rotor-shaft seals are semi-metallic packing in... 

Metallic packings of aluminum, copper and lead cover a very wide temperature range up to 540°C (1000°F). They should be matched to the shaft material, since shaft finish and tolerance are critical factors in overall efficiency. The great limiting factor in the use of metallic packing is the difficulty of ensuring corrosion resistance with all the likely process materials. 

Emergence of new interactions. For example iodine (high pressure, metallic, packing of spheres) -t I2 molecules (normal pressure). 

Ceramic and metal packings are normally dumped into the column wet , to ensure a truly random distribution and prevent damage to the packing. The column is partially filled with water and the packing dumped into the water. A height of water must be kept above the packing at all times. 

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