Pressure drop in packed columns

A new generalised correlation for pressure drop in packed columns, similar to Figure 11.44, has been published by Leva (1992), (1995). The new correlations gives a better prediction for systems where the density of the irrigating fluid is appreciably greater than that of water. It can also be used to predict the pressure drop over dry packing. 

Gayler, R. and Pratt, H. R. C. Trans. Inst. Chem. Eng. 29 (1951) 110. Symposium on liquid-liquid extraction. Part II. Hold-up and pressure drop in packed columns. 

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

An alternate correlation for the pressure drop in packed columns was proposed by Strigle and is shown in Fig. 22.7. The abscissa is essentially the same as for Fig. 22.6, but the ordinate includes the capacity factor Cj = o JpyRpx — where Uj, >s the superficial velocity in ft/s. The kinematic viscosity of the liquid, v, is in centistokes. The semilog plot permits easier interpolation than the log-log plot, though both correlations are based on the same set of data. 

Blok JR. Varkevisser J, Drinkenburg AAH. Transition to pulsing flow, holdup and pressure drop in packed columns with cocurrent gas-liquid downflow. Chem. Eng. Sci. 1983 38 687. 

PRA 69] Prahl W.L., Pressure drop in packed columns . Chemical Engineering, p. 89, 11 August 1969. 

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... 

Berner GG, Kalis GAJ. A new method to predict hold-up and pressure drop in packed columns. Trans. 1. Chem. Eng., Vol. 56 (1978), p. 200/205... 

The allowable pressure drop influences the choice of the particle size and helps determine the column length. Equations for estimating the pressure drop in packed beds are given in Section 6. 

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... 

Reduce the pressure drop in the column by using packings instead of trays, if possible. 

Dalla Valle1 s Method—The author used an equation due to Burke and Plummer (1928) for determining the pressure-drop through packed columns. For streamline flow of air through packings of various sands in a 3 in. diameter column, the modified Burke-Plummer equation takes the form... 

Example 6 Estimation of pressure drop in packed tower. A column 2 ft in... 

The product throughput in the unit is not influenced by the size of the packing. However, the particle size affects the pressure drop in the column and therefore influences the operating costs. Also, because peak resolution is influenced by particle size, it is possible to enhance the separation efficiency by decreasing the particle size. 

Liquid and vapor flow caimot be regarded independently from each other. The pressure drop in the column rises with increasing vapor load. This effect increases with increasing liquid load since void fraction of the packing for the vapor flow becomes smaller. 

In 1990/1991, Madkowiak [26, 27] described an additional method for determining the pressure drop of packed columns with any type of column internal throughout the entire operating range up to flooding point, based on the knowledge of the resistance factor ]tlv for two-phase counter-current flow. The equations and numerical examples can be found in Chap. 5. 

Pig. 22. Schematic representation of typical pressure drop as a function of superficial gas velocity, expressed in terms of G = /9q tiQ, in packed columns. O, Dry packing , low Hquid flow rate I, higher Hquid flow rate. The points do not correspond to actual experimental data, but represent examples. 

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