Packed-Column Pressure Drop

Example 13 Packed Column Pressure Drop Air and water are flowing coiinterciirrently through a bed of 2-inch metal Pali rings. The air mass velocity is 2.03 kg/s-m (1500 Ihs/hr-fd), and the liquid mass velocity is 12.20 kg/s-m (9000 Ihs/hr-fr). Calculate the pressure drop hy the generalized pres-... 

Fluid flow in packed columns Pressure drop... 

The channel model This model attributes packed-column pressure drop to the resistance to flow in a multitude of parallel channels. The channels may have bends in them or may have contractions and enlargements. Liquid flows down the walls of the channel, thus consuming some of the available cross-section area. This in turn increases the pressure drop. The channel model has been applied both for random and structured packings (e.g., 3,62,736,78,91,92,93a), A popular application of this model is the Bravo et al. (91) correlation for structured-packing pressure drop ... 

It is proposed, as an alternative to trays, to pack the same column with Koch-Sulzer structured packing, with a packing factor of 200m-/m- . Using the same fluid flow rates and properties as in the trayed design, estimate the packed column pressure drop, and check for the possibility of flooding or channeling. 

FIGURE 15.4 Packed column pressure drop correlation. (Reprinted with permission from J. S. Eckert, Chem. Eng., 82(8). 70, 1975.)... 

Preserving consistency with units used in the packed column pressure drop correlation (Figure 15.4),... 

We opened the Packed Columns subsection with the statement by Lieberman that, based on his design and operating experience, a properly designed packed tower can have 20 0% more capacity than a trayed tower with equal number of fractionation stages. Kister states that packing s pressure drop is typically three to five times lower than that of trays. 

Ellenberger J, Krishna R. Countercurrent operation of structured catalytically packed distillation columns pressure drop, holdup, and mixing. Chem Eng Sci 1999 54 1339-1345. 

The time of analysis in HPLC may be reduced by using well-packed columns, low viscosity eluents and high column pressure drops. 

It is interesting to compare the flow characteristics of both types of silica columns with respect to the column pressure drop and column permeability. The column pressure drop / flow rate curves of both types indicate a much lower slope of the monolithic columns (not shown) than the particulate columns. In other words, the column pressure drop of the monolithic columns corresponds to that of a column packed with 15 pm silica particles [6]. The column permeability values are listed in Table 3. 

Differential pressure control is often used on packed columns to ensure that the packing operates at the correct loading see Figure 5.27d. Differential pressure control should not be used on trayed columns, as column pressure drop is relatively... 

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