Structured packing efficiency

Structured packing efficiency is about 1.5 times that of plates or random packing. 

The structured packing efficiency is about 50% higher than either the trays or the random packing. 

It may be that the random or structured packing efficiency is degraded by the need to limit the bed-height space required for liquid collection redistribution, and by maldistribution and channelling in the packing [33]. 

Harrison and France (loc. cit.) presented the only published rule of thumb for structured packings efficiency as a function of packing crimp. Raster and Larson reexpressed it in terms of the surface area per unit volume to accommodate a wider range of packing geometries. The final expression is... 

To maximize the specific surface area, i.e., the surface area per unit volume This maximizes vapor-liquid contact area, and therefore, efficiency (see Fig. 3.126 and Sec. 3.1.10). A corollary is that for random packings, efficiency generally increases as the particle size is decreased (Fig. 8.7) for structured packings, efficiency generally... 

At deep vacuum (< 1 to 2 psia) there are data to suggest that efficiency decreases as pressure is lowered for random packings (117,118), but most of these data can also be explained by poor wetting or maldistribution. For distillation at high pressures (>200 to 300 psia), there is evidence to suggest that structured-packing efficiency diminishes as pressure is raised (24,31a). 

The Bravo, Fair ei al. correlation for structured pecking. Bravo, Rocha, and Fair (124) developed the first published fundamental model for structured-packing efficiency. This model was developed for the Sulzer BX wire-mesh packing, but has recently (25,50) been extended to... 

Harrison and France (52) presented the only published rule of thumb for structured packings efficiency. This rule states that HETP is 9 in for Winch crimp height, 18 in for 1/2-inch crimp, and 33 in for 1-in crimp. The author found this rule to do well when the crimp angle is 45°, but to be less satisfactory for other angles. Basad on data in Chap. 11, the author proposes an alternative rule of thumb. 

Shortcut method. For orientation and conceptual design, a shortcut method for structured packing efficiency should be con-... 

Lockett Chem. Eng. Progr., p. 60, January 1998) simplified the fundamental Bravo-Fair-Rocha correlation [Ind. Eng. Chem. Res. 35, p. 1660 (1996)] to derive an alternative rule of thumb for structured packing efficiency. This rule of thumb predicts HETPs under perfect distribution conditions. Lockett recommends caution when applying... 

A number of pilot-scale investigations have been reported on the effect of a fixed slant on random and structured packing efficiency (162, 283, 323, 390, 428, 434). In all cases, slanting lowered packing effi-... 

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