Eckert’s correlation

Belles and Fair (55) compared flood-point predictions from the Eckert correlation to published experimental data for random packings. Their massive data bank consisted mainly of data for first-generation packings, but also included some data for second-generation packings. For the data compared, Bolles and Fair showed that Eckert s correlation gave reasonable flood-point prediction. Statistically, they showed that if a safety factor of 1.3 was applied to the correlation flood-point predictions, the designer will have 95 percent confidence that the column will not flood. 

Figure 8.19 The latest version of the GPDC pressure drop correlation, (a) The latest log-log version of Eckert s correlation, as presented by Strigle (15). (Part a from Ralph F. Strigle, Jr Random Packings and Packed Towers. Copyright 1987 by Gulf Publishing Company, Houston, Texas. Used with permission. All rights reserved.)...

Chrastil s correlation, the empirical basis for which had previously been noted by Stahl [74], is discussed alongside other density-based correlation methods in [73]. Ziger and Eckert s correlation [75] which is based on solubility parameters, is also discussed. 

The empirical flooding point correlation developed by Billet [15] applies to metal Raschig and Pall rings and reflects the experimental data for the vapour/liquid systems much more accurately, 5(uv,fi) = i 15—20%, than Eckert s correlation [9] does. 

BoUes and Fair [8] compared data found in literature, in particular experimentally derived data provided by Billet [15], with the values calculated using Eckert s correlation [9]. The comparison also showed that the values for the vapour velocity Uv,fi. which were calculated using Eckert s correlation, were 50% higher than the numerical values which were experimentally derived, particularly for systems in the vacuum range and for larger-diameter packing elements. Consequently, the correlation valid for air/water is not applicable to vapour/liquid systems. 

Pall rings made of metal d = 0.025-0.050 m various systems up to flooding point comparison of data by Billet [5], Teutsch [16], et al. with Eckert s correlation Molzahn, Wolf [25]... 

Eckert s modification of Sherwood s flooding correlation has been widely applied for designing packed columns. Blackwell [13] developed... 

Figure 3.9 Generalized pressure-drop correlation, upper and lower curve limits. (From J. S. Eckert, Design Techniques for Sizing Packed Towers, Chem. Eng. Progress 57(9), 1961. Used by permission of Chemical Engineering Progress.)...

Figure B.17 The Eckert 1970 version of the GPDC correlation. (From J. S. Eckert, Ckem. Eng. Progr., 66(3), March 1970, p. 39. Reproduced courtesy of the American Institute of Chemical Engineers.)...

Figure 15.4 shows the Eckert (1975) pressure drop correlation, which may also be used to check the approach to flooding conditions. The variables in the coordinates are defined as follows L and V are the liquid and vapor flow rates, Ibmol/hr, G is the vapor mass velocity, Ib/tt-s, p, and Pv are the liquid and vapor densities, Ib/fF, F is the packing factor, ft /fF, and is the liquid viscosity, centipoise. The column diameter is implied since G is the vapor rate per unit column cross-sectional area. The pressure drop, in inches of water per foot of packing, is reported as a parameter in this correlation. Flooding can be expected to occur at any point above the pressure drop curve of 1.5 in. of water per foot of packing. 

Figure 13-6 The Eckert flood velocity correlation. (Fp = packing factor, ft"1 see Table 13-7. g = acceleration of gravity, ft/s2. Gvsf = mass velocity of the vapor, superficial, flood, lb/s-ft2. wL = liquid mass flow rate, lb/s. wv = vapor mass velocity, lb/s. pv = density of vapor, lb/ft3. pL = density of liquid, lb/ft3. p, = viscosity of vapor, lb/ft-s. pw — viscosity of water, lb/ft-s.) [J. S. Eckert, Chem. Eng. Prog.. 63(3) 39 (1949), by courtesy American Institute of Chemical Engineers.]...

Figure 13-7 The Eckert correlation of the pressure gradient. (G s = superficial mass velocity of the vapor, lb/s-ft2. Remaining symbols are defined in Fig. 13-6.) [J. S. Eckert, Chem. Eng. Prog., 63(3) 39 (1970), by courtesy American Institute of Chemical Engineers.]...

FIGURE 15.4 Packed column pressure drop correlation. (Reprinted with permission from J.S. Eckert, Chem. Eng., 52(8), 70, 1975.)... 

Figure 8.1.11. The ordinate of this log-log plot (Eckert, 1970), (jG Fpy/uf /pgPig, often called the capacity factor, Cp, contains the following quantities, specified with their units Gg is the superficial mass average gas velocity based on empty column cross section v gPg (Ibmass/ft -s) Fp is a packing factor (unit of 1/ft) yr is the ratio of p.. ,pi lpt, where p is the density of the liquid in Ibmass/ft pg is the liquid viscosity in centipoise Pg is the gas density in Ibmass/ft gc = 32.2. This correlation is such that the specified units for each quantity in the ordinate has to be used. The quantity Fp (unit, 1/ft) is approximately inversely proportional to the packing size (Wankat, 2007) Fp oc (characteristic packing dimension, in inches) . The abscissa of this plot (often called the flow parameter).

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