Maldistribution, packings, liquid large-scale

Figure 0.7 Comparing the effects of "small-scale and large-scale" maldistribution on packing HETP. (a) Comparing the effect of a simulated continuous tUt (max/ min flow ratio = 125 ) to the simulated effect of blanking a chordal area equal ts 11 percent of the tower area, (b) Comparing the effects of simulated continuous tilts (max/min flow ratios 125 and 1.5) to the effects of a situation where one-half of the distributor passes 25 percent more liquid to the other hen. (c) Comparing the effects of random maldistribution to these of zonal maldistribution. (Ae-...

Hoek, P.J. Wesselingh, J.A. Zuiderweg, F.J. Small scale and large-scale liquid maldistribution in packed columns. Chem. Eng. Res. Des. 1986, 64, 431-449. 

A packed column has reasonable tolerance for a uniform or smooth variation in liquid distribution and for a variation that is totally random ("small-scale maldistribution ). However, the impact of discontinuities or zonal flow ("large-scale maldistribution ) is much more severe (219, 221, 222, 442, 443). 

When this arrangement is used, caution is required to ensure that the drawoff does not generate large-scale maldistribution of liquid to the bed below (see Sec. 3.1) and that unirrigated areas do not form on top of the packing under the drawoff pipe or sump. This is most likely to be a problem when a submerged drawoff nozzle or sump is used. 

Hoak, P. J., Large and Small Scale Liquid Maldistribution in Packed Column, Ph.D. Thesis, Delft University, Netherland, 1983. 

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