Flooding capacity diagram

Mozenski and Kucharski [2] examined the pressure-drop, overload limit, and flooding limit of a column (0.5 m diameter) packed with Pall rings (35 mm diameter) and Bialecki rings (35 mm and 50 mm diameter) sprayed with propylene carbonate up to 15 bar. Some specific correlations have been proposed and compared with literature data for atmospheric pressure, particularly with the use of the Sherwood diagram for loading-and flooding capacities. 

The typical hydraulic characteristics of a packed column are shown in Fig. 7-7, plotting the correlation between the dispersed phase hold-up hp and the specific flow rate of the dispersed phase up. The parameter here is the specific flow rate of the continuous phase Uc. This figure shows the course of the most important parameters of a packed column in a single diagram. Up to 65 % of the flooding capacity ud fi> the flow rate of the continuous phase uc has practically no influence on the dispersed phase hold-up. 

The following Figs. 7-10, 7-11, 7-12 and 7-13 show the capacity diagrams for a number of different packed columns, using various systems, acc. to Table 7-1 [11,12,13,14]. They form the basis for the development of the author s own model for determining the flooding capacities in non-pulsed extraction columns [15]. 

Mersmann (1980) [17] has developed a graphic model for determining the specific flow rate of the dispersed phase at the flooding point, using a capacity diagram, see Fig. 7-14, which is applicable to any types of packings, packing structures and materials. 

Figure 7-17 [15] shows a comparison between the experiment and the calculated flooding point data, Eq. (7-21), with the parameter m= 1.9 for pure binary mixtures and ternary mixtures C D and for the mass transfer direction D C with the parameter m = 1.5. As can be seen from the comparison, the experimental data has been verified by calculation with an accuracy of less than 20 %. It was therefore possible to significantly consolidate and generalise the information available on the loading capacity of non-pulsed extractors, compared to Mersmann s flooding point diagram shown in Fig. 7-14. 

Fig. 24. Souders load diagram for capacity limit determination for four stmctured packiags of the Sul2er-MeUapak type. The soHd lines represent the capacity limits of the respective packiags as defiaed by a pressure drop of 1.2 kPa/m (A) 125 Y (B) 250Y (C) 350Y (D) 500 Y. Flooding rates are about...

Figure 6.6 is a typical tray stability diagram. The area of satisfactory operation (shaded) is bound by the tray stability limits. These limits are discussed in the following sections. The upper capacity limit is the onset of flooding. At moderate and high liquid flow rates, the entrainment (jet) flooding limit is normally reached when vapor flow is raised, while the downcomer flooding limit is normally reached when liquid flow is raised. When flows are raised while the column operates at constant LIV (i.e., constant reflux ratio), either limit can be reached. At very low liquid rates, as vapor rate is raised, the limit of excessive entrainment is often reached. 

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