Packings Pall ring

Type of packing Pall ringe (M) Pall rings (M)... 

Packing Pall rings Third-generation random... 

Packing Pall rings Holpack Honeycomb MeUapak250Y... 

Table 3 compares packings as an aid to initial selection. For simple applications use Pall Rings for studies as a tried and true packing. This will give conservative results when compared w ith more recent random packings. 

Cost of the packing and its effect on the system costs must be considered, as some packings are much more expensive than others, yet produce very little improved performance. Table 9-17 presents some comparative information. The most common packings and hence the ones with the most available data are Raschig rings, Berl saddles, several saddle types and Pall Rings (Norton Co.) or equivalent. 

Figure 9-26. SLE Data Chart for 1-in. metal Pall rings, aqueous systems, pressure drop only. Data from 15-84 in. dia. test columns with packed heights of 2-10 ft. Reproduced with permission of the American Institute of Chemical Engineers, Kister, H. Z. and Gill, D. R., Chemical Engineering Progress, V. 87, No. 2 (1991) p. 32 all rights reserved.

Figure 9-28. Packing comparison at design point for IntaJox ceramic saddles, metal pall rings, and metal IntaJox . Reproduced by permission of American Institute of Chemical Engineers, Strigle, R. F., Jr. and Rukovena, F., Chemical Engineering Progress, Mar. (1979) p. 86 all rights reserved.

Superior surface utilization in mass and heat transfer, allowng shorter packed bed heights. Turn-down performance is superior over 2-in. and 3) -in. Pall rings. 

Figures 9-32A and B [98] illustrate the correlation of wet pressure drop and system vapor rate at various liquid rates for No. 2 Nutter rings however, other available data indicate that other sizes of Nutter rings, Pall rings, and selected other packing shapes correlate in the same manner.

The flooding of the packing is a direct function of the a/e, therefore it is valid at constant separation to examine the performance as shown. The metal Pall rings appear to allow for a considerable increase in capacity. In fact the condition at 35.2% of flood might not be good from a contact efficiency standpoint. 

Figure 9-65. Performance of structured gauze packing vs. Pall rings. Used by permission of Biiiet, R., Chemical Engineering, V. 79, No. 4 (1972) p. 68 ali rights reserved.

On the basis of this better performance of the Pall ring, a smaller diameter tower must be selected and the tower reevaluated based on the new mass flow rates with this packing. The economics require that the higher packing cost, smaller tower diameter, new total packing volume, and tower pressure drop be considered. 

Packed towers are employed when 5-10 stages suffice. Pall rings of 1-1.5in. size are best. Dispersed phase loadings should not exceed 25 gal/(min) (sqft). NETS of 5-10 ft may be realizable. The dispersed phase must be redistributed every 5-7 ft. Packed towers are not satisfactory when the surface tension is more than 10 dyn/cm. 

Extraction column packed column, diameter 0.5 m, height 4 m, packed height 3 m, packing 25 mm stainless steel pall rings, design pressure 2 bar, material carbon steel. 

Figure 11.37. Types of packing (Norton Co.), (a) Raschig rings (b) Pall rings (c) Berl saddle ceramic (d) Intalox saddle ceramic (e) Metal Hypac (/) Ceramic, super Intalox...

The HETP for saddle packings will be similar to that for Pall rings providing the pressure drop is at least 29 mm per m. 

Their correlations were based on a large amount of data on gas absorption and distillation with a variety of packings, which included Pall rings and Berl saddles. Their method for estimating the effective area of packing can also be used with experimentally determined values of the mass-transfer coefficients, and values predicted using other correlations. 

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