Random packed towers

Eckert [125] provides some basic guidelines to good packing selection for various system performance requirements. Kunesh [126] illustrates the often-determined pressure drop advantage of random packed towers over the usual valve tray. See Figure 9-19 [126],... 

A packing pressure drop of 1.5 in/ft is approximately 95% of column packing flood. At 2.0 in/ft of pressure drop DP, most random packed towers are at the flood point. It is thus prudent and good practice to keep the limiting D, at 1.5 in/ft or less. 

Redistributors and wall wipers counteract the spread of liquid toward the wall. There is uncertainty regarding their effectiveness in keeping the liquid off the walls of randomly packed towers (144). It appears that their main value is in promoting lateral mixing (Sec. 9.2.3). In structured packings, well-designed wall wipers were shown (67) to effectively keep liquid off the wall. 

Random-packed towers are seldom designed with diameters larger than 4 ft, and diameters of commercial plate towers are seldom less than 2 ft. 

S. Piche, B. P. A. Grandjean, I. niuta, and F. Larachi, Interfacial mass transfer in randomly packed towers a confident correlation for environmental applications. Enviorn. Sci. Technol. 35(24), 4817 (2001). 

Ind. Eng. Chem. Res. 41,4911 (2002)] developed two correlations for reconciling the gas-liquid mass-transfer coefficient and interfacial area in randomly packed towers. The correlation for the interfacial area was a function of five dimensionless groups, and yielded a relative error of 22.5 percent for 325 data points. That equation, when combined with a correlation for Nsh as a function of four dimensionless groups, achieved a relative error of 24.4 percent, for 3455 data points for the product k cfl. 

In general, pressure drop per unit height is least for towers with structured packings and greatest with tray towers, with randomly packed towers in between. For sieve trays, the components of the pressure drop are (1) pressure drop through the holes in the tray, which depends... 

Figure Flooding and pressure drop in random-packed towers. For SI units I, Cf from Table 6.3, and use / = 1. For G = Ib/ft h, p = lb/fl cP, 4.18 X 10 , q from Table 6.3, and use J — 1.502. [Coordinates of Eckert (35), Chemical Process Products Division, Norton Co.)...

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