Pressure drop, random packing

Figure 9-23. Flood pressure drop vs. packing factor for random packings. Reproduced with peimission of the American Institute of Chemical Engineers, KIster, H. Z. and Gill, D. R., Chemical Engineering Progress, V. 87, No. 2 (1991) all rights reserved.

Figure 1337. Corn-elation of flow rates, typical pressure drop behavior, and packing factors of random packed beds. [Eckert, Foote, and Walter, Chem. Eng. Prog. 62(1), 59 (1966) Eckert, Chem. Eng. 14 Apr. 1975)]. (a) Correlation of flow rate and pressure drop in packed towers, (b) Typical pressure drop data 2 in. porcelain intalox saddles, with F = 40, in a bed 30 in. dia by 10 ft high, (c) Packing factors, F, of wet random packings-...

Metallic or ceramic foams exhibit several advantages over randomly packed beds [34]. Open cell foams consist of a network of interconnected rods, which delineate cavities (called cells). Metallic foams have porosities of up to 95% and ceramic foams of 75-85%. Examples are shown in Figure 11.16. Foams are characterized by considerably lower pressure drops than packed beds for comparable characteristics (such as specific geometrical surface area) and at a given superficial fluid velocity consequently, they are an interesting alternative to catalyst pellets. 

Several structured packing elements have been compared with regard to catalyst holdup, heat transfer performance, and pressure drop [120]. The results indicate that using catalyst coating gave lower pressure drop than packed beds but had a much lower catalyst inventory per reactor volume. On the other hand, a particle-packed structure exploited the advantages of structured flow vdiile not sacrificing much in catalyst holdup compared to a randomly packed bed. This alternative retained the favorable pressure drop characteristics so that smaller particle-sized catalysts could be used. Despite their lower... 

Metal Random Packing - Superior random packings combined with innovative mass transfer technology. Technical Information by Sulzer Chemtech Ltd., 22.64.06.40 - IV.06 - 50, Switzerland Billet R, Schultes M. Modelling of pressure drop in packed columns. Chem. Eng. Technol. vol. 14... 

Fig. 23. Pressure drop and flooding correlation for various random packings (95). ip = p- o IP-l (standard acceleration of free fall) = 9.81 m/s, p, = liquid viscosity ia mPa-s numbers on lines represent pressure drop, mm H2O /m of packed height to convert to ia. H2O /ft multiply by 0.012. Packing...

Tower Internals and Equipment Modification. Tower capacity expansion can be achieved through the use of random or stmctured packing, or through the use of higher capacity trays such as the UOP multiple downcomer tray. Packing has been used in the gasoline fractionator, water quench tower, caustic and amine towers, demethanizer, the upper zone of the deethanizer, debutanizer, and condensate strippers. Packing reduces the pressure drop and increases the capacity. 

Sepn. Purif., 3, 19 (1989)] takes holdup into account and applies to random as well as structured packings. It is somewhat cumbersome to use and requires three constants for each packing type and size. Such constants have been evaluated, however, For a number of commonly used packings. A more recent pressure drop and holdup model, suitable for extension to the flood point, has been pubhshed by Rocha et al. [Jnd. Eng. Chem. Research, 35, 1660 (1996)]. This model takes into account variations in surface texturing of the different brands of packing. 

Representative pressure drop data for random and structured packings are given in Figs. 14-52-14-54. 

FIG. 14-50 Pressure drop correlation for random packings, as presented hy Robbins. [Cbem. Eng. Progr., 87(1), 19 (1990). Reproduced with peimission of the Ameiican Institute of Chemical Engineers. Copytight 1990 AlChE. All fights reseroed. ] To convert inches H20/ft to mm H20/m, multiply by 83.31. 

Distillation Applications Packings are now routinely considered for distillation columns with diameters up to 10 m or more. The pressure drop advantages of the modern, through-flow random pack-... 

Lucas and Porter (U.S. Patent 3,370,401, 1967) developed a fiber-bed scrubber in which the gas and scrubbing liquid flow vertically upward through a fiber bed (Fig. 17-55). The beds tested were composed of knitted structures made from fibers with diameters ranging From 89 to 406 [Lm. Lucas and Porter reported that the fiber-bed scrubber gave substantially higher efficiencies than did venturi-type scrubbers tested with the same dust at the same gas pressure drop. In similar experiments, Semrau (Semrau and Lunn, op. cit.) also found that a fiber-bed contactor made with random-packed steel-wool fibers gave higher efficiencies than an orifice contactor. However, there... 

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). 

Table 7 show s ranges of pressure drop for design. Pressure drop sets the allowable vapor flow rate. The flood pressure drop, for random or structure packings, is given in Reference 15 as ... 

Tlie flood pressure drop for structured packing, already shown in the subsection on random dumped packings, is repeated here ... 

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