Structured packing flooding

Rgure B.1S GPDC interpolation plots for structured packings flood points, i.o) The Fair and Bravo plot for Sulzer BX and Mellapek 250Y. (Part a. from J. R, Fair and J. L, Bravo, I, Citem, E, Symp. Ser, No. 104, p. A183,... 

Figure B.1B (Continued) GPDC interpolation plots for structured packings flood points, (b) The Billet plot for several structured packings (cj the Spiegel and Meier plot for Mellapak , (Part b from R, Billet, Packed Column Analysis and Design, Ruhr University, Bochum, 1989, reprinted courtesy of Ruhr University part e, from L. Spiegel and W. Meier, 1. Chem. E. Syrtip. Ser. 104, p. A203, 1987 reprinted courtesy of the Institution of Chemical Engineers (UK).)...

Figure 8.1 B (Continued) GPDC interpolation plots for structured packings flood points. (d) The Dolan, Hausch and Petschauer plot for Intelox 2T Structured Packing. (Port d. from G,W. Hausch, P. Quvtson, and K. Seeger, Structured Packing Revamp of a 305 Psig Depropanizer, paper presented at the AJChE Annual meeting, Los Angeles, California, November 1991 reprinted courtesy of the Norton Company,)...

Berl saddle. 423, 424, 500. 530 Bialecki rings, 484, 486 Billet structured packing flood, 488, 490 Billet and Schultes packing ... 

For ordered, or structured, packings, pressure-drop estimation methods have been reviewed by Fair and Bravo [Chem. Eng. Progr, 86(1), 19 (1990)]. It is not common practice to use the packing factor approach for predicling pressure drop or flooding. For operation below the loading point, the model of Bravo et [Hydrocarbon... 

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. 

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 ... 

The heavy naphtha-Ught gas oil fractionation zone of a crude tower has to be revamped to handle 25% more capacity. Because trays would be working at high percent flooding, Gempak structured packing is condensed (Figures 9-56A-D). 

Pressure drop through gauze and sheet metal structured packings [115] applies for the region below the loading point and cannot predict the flood point because liquid holdup vs. gas velocity is not included. The latest version of the equation is in Reference 108 ... 

Figure 9-62. Flooding data for structured packings as reported by Billet [109]. Numbers following packing type indicate specific surface area in m /m. Reproduced by pennis-sion of the American Institute of Chemical Engineers, Fair, J. R. and Bravo, J. L., Chemical Engineering Progress, V. 86, No. 1 (1990) p. 19 all rights reserved. Note, Uq = vapor velocity, meters/sec.

Lockett MJ. Flooding of rotating structured packing and its application to conventional packed columns. Trans IChemE 1995 73(Part A) 379-384. 

Kister and Gill compared flood-point predictions from Eq. (8.1) to their massive data banks for second and third-generation random packings (60) and for structured packing (60a). Pressure drops were calculated using the Kister and Gill GPDC interpolation charts (Sec. 8.2.9). They showed that Eq. (8.1) predicted all the flood points in their data bank to within 15 percent and most to within 10 percent. 

The Billet and Schultes correlation applies both to random and structured packings, has a good theoretical basis, and was demonstrated (79) to predict a large number of flood data to within 10 percent. On... 

Mackowiak (73a, 736) derived a new flood correlation. Like the Billet and Schultes correlation, it is based on the drop entrainment modal and takes liquid holdup into account. Unlike Billet and Schultes, Mackowiak uses a different set of premises and expressions. Ma6ko-wiak s correlation applies for both random and structured packings, has a good theoretical basis and was shown (73a, 786) to predict a large number of flood data to within 8 percent. On the debit side, the correlation is complex and requires the availability of four constants for each packing. Matkowiak also states (73a) that for high liquid rates, Mersmann s film model is more suitable than his drop model. 

Chapter 10 presents a compendium of GPDC data interpolation charts for flood, MOC, and pressure drop prediction, both for random and structured packings. When flood data are absent, pressure drop data can be used for approximating the flood point using Eq. (8.1). 

The particle model This model attributes pressure drop to friction losses due to drag of a particle. The preeence of liquid reduces the void fraction of the bed and also increases the particle dimensions. Ergun (94) applied this model for single-phase flow (e.g., fixed and fluidized beds). Stichlmair et al. (95) successfully extended this model to correlate pressure drop and flood for both random and structured packings. Their correlation is complex and requires some additional validation, but is the most fundamental correlation available. 

For wire-mesh structured packings, due to the excellent wetting characteristics of the surface, as well as for corrugated-sheet structured packings at above 85 percent of flood, the packing surface is fully wetted, i.e.,... 

For corrugated-sheet structured packings at less than 85 percent of flood only a portion of the surface is wetted, and this portion is a function of the surface Reynolds number. For design purposes, Bravo et al. recommended estimating the wetted frection from... 

A 5.5-ft-diameter tower is to be used to countercurrently contact a vapor stream and a liquid stream. The mass flow rates are 150,000 lb/h for both. The liquid density is 50 lb/ft3, and the gas density 1 lb/ft3. Determine the approach to flooding at constant liquid loading L and at constant liquid-to-vapor ratio (L/V) for Flexipac type 2Y (FP2Y) structured packing. 

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