Packed column generalized pressure drop correlation

The drop in pressure with the depth of packing is a key design variable, particularly for columns in vacuum service. The most reliable correlation is the generalized pressure-drop correlation of Leva25 as refined by Eckert,11 which is referred to as the Eckert model. This correlation, presented in Fig. 13-7 is of the form... 

Figure 4.5 Generalized pressure-drop correlation for packed beds. (Generated using the Packed Column Calculator, version 1.1, Katmar Software, 1998.)...

A generalized pressure drop correlation for packed columns with counter-current flow has been derived by Sherwood et al. [6] and adapted by Lobo et al. 

Figure 14.3.a-2 Generalized pressure drop correlation for packed columns with countercurrent flow. Parameter curves pressure drop, in inches water per foot (from Eckert [76]). 

The packing factors given in Table 1-4 are for use with these generalized pressure drop correlations (Figures 1-15 and 1-16). These packing factors have been determined from experimental pressure-drop data therefore, they are empirical rather than theoretical in nature. The use of pressure drop to determine column size is discussed in detail in Chapter 3. 

Figure 10-27. Generalized flooding and pressure drop correlation for packed columns.

The pressure drop through packed columns, and the flooding conditions, can be estimated from the generalized correlation of Leva (1992), shown in Fig. 13-5. The pressure gradient in millimeters of water per meter of packed height is the parameter on the curves, and interpolation is usually necessary to determine the pressure drop (note that the pressure... 

A new generalized correlation for pressure drop in packed columns, similar to Figure 11.46, has been published by Leva (1992, 1995). The new correlations give a better... 

Figures 9-21F and 21G (for Norton s IMTP packing only) can be up to 20% higher than industrial experience for the same Cj values at a flow parameter (FP) of 0.01 [82]. At an absolute column pressure of 10 mm Hg or less, the pressure drop actual can be up to 30% lower than that read from the Figure 9-21F at the FP of 0.01 and the same Cj value [82]. The conclusion is that the generalized correlation, Figures 9-21F and -21G always give a conservative design AP at operating pressures less than 70 mm Hg abs. Several other factors must be considered, such as variability of gas and liquid rates and densities or specific volumes.

Generalized correlation for flooding and pressure drop in packed columns. After Eckert )... 

Pressure drop in flow through packed columns has been investigated by Furnas,Chilton and Colburn,and more recently by Leva and Ergun. The same general trends were observed in all these investigations, although the experimental data show considerable scatter, probably due to differences in voidage and/or wall effects for which corrections were not always applied. The data may be conveniently correlated in terms of a dimensionless friction factor (/), defined by... 

The generalized method developed by Bravo et al can be used to predict the pressure gradient of structured packings (see Chapter 2) [3]. Normally vacuum towers are not operated in the loading region of the packing, due to the column pressure drop restriction. This correlation is based on data with C values as low as 0.05 ft/s. 

---