*% voids vary with material thickness and values may not be consistent.

fPacking factors from Kister, Distillation Design, McGraw-Hill, 1992; Kister, Larson, and Gill, paper presented at the Houston AIChE Meeting, March 19-23, 1995; and Kister et al., in Distillation 2007: Proceedings of Topical Conference, AIChE Spring Meeting, Houston, Tex., April 22-26, 2007. ^Dry packing factors from Robbins, Chem. Eng. Prog., p. 87, May 1991. «These packing factors supplied by the packing vendor. ^These are expanded metal packings.

"First figure is for hydrocarbon service, second figure for aqueous service.

Vendors: Sulzer Chemtech Ltd., Winterthur, Switzerland; Koch-Glitsch LLP, Wichita, Kansas; Raschig GmbH, Ludwigshafen/Rhein, Germany; Julius Montz GmbH, Hilden, Germany; Knit Mesh/Enhanced Separation Technologies, Houston, Texas; Kuhni Ltd., Allschwil, Switzerland.

Analysis and Design, Ruhr University, Bochum, Germany, 1989) methods. Stichlmair et al. (Distillation Principles and Practices, Wiley, New York, 1998; Gas Sep. Purif. 3, March 1989, p. 19) present alternative correlations using the particle model, that attributes packing pressure drop to friction losses due to drag of a particle. This is similar to the Ergun model for single-phase flow [Chem. Eng. Prog. 48(2), 89 (1952)].

Example 13: Packed-Column Pressure Drop Air and water are flowing countercurrently through a bed of 2-inch metal Pall rings. The air mass velocity is 2.03 kgfem2 (1500 lbs/hrft2), and the liquid mass velocity is 12.20 kgfem2 (9000 lbs/hrft2). Calculate the pressure drop by the generalized pressure drop (GPDC, Fig. 14-55) and the Robbins methods. Properties: pG = 0.074 lbs/ft3; pL = 62.4 lbs/ft3, |L = 1.0 cP, v= 1.0 cS. The packing factor Fp = 27 ft-1. For Robbins, Fpd = 24 ft-1. The flow parameter Flo = L/G (pGpL)0.5 = (9000/1500) (0.074/62.4)05 = 0.207. The F-factor = F. = U,pG5 = G/(pG53600) = 1500/[(0.074)a5 (3600)] = 1.53 f^s(lb/ft3)05.

Using the GPDC method, the capacity parameter [by Eq. (14-140)] =

Referring to Fig. 14-55, the intersection of the capacity parameter and the flow parameter lines gives a pressure drop of 0.38 inches H2O/ft packing.

Using the Robbins method, Gf = 986Fs(Fpd/20)°.5 = 986(1.53)(24/20)°-5 = 1653. Lf = L (62.4/pL)(Fpd/20)°.5 ^o-1 = 9000 (1.0)(1.095)(1.0) = 9859. Lf/Gf = 5.96. From Fig. 14-58, pressure drop = 0.40 in. H2O/ft packing.

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