Dumped-type packings

In general the dumped saddle type packing should give less blocking to support openings than ring type. 

Calculating pressure drop is of considerable importance in atmospheric absorbers, heat transfer services, and vacuum distillations. Although pressure drop plots are available for most commercial types and sizes of random dumped tower packings, these data usually have been collected on air/water systems. While the air flow rate can be corrected for changes in gas density, no adequate method exists for handling the effect of liquid properties. 

In liquid-film-controlled systems the value of Koa primarily is a function of the liquid flow rate. For most random dumped tower packings the value of the exponent b in Equation 3-13 lies between 0.22 and 0.34 the exact value is characteristic of the type of packing employed. If data on the particular packing are not readily available, it is suggested that this exponent be assumed as 0.30 for preliminary designs. In such liquid-film-controlled systems there is a very small effect of gas rate. The value of the exponent c in Equation 3-13 normally is only 0.06 to 0.08. Thus, if a standard Koa value for such a system is determined to be 6.0 Ib-mol/h... 

Earliest type, usually cheaper per unit cost, but sometimes less efficient than others. Available in widest variety of materials to fit service. Very sound structurally. Usually packed by dumping wet or dry, with larger 4-6-inch sizes sometimes hand stacked. Wall thickness varies between manufacturers, also some dimensions available surface changes with wall thickness. Produce considerable side thrust on tower. Usually has more Internal liquid channeling, and directs more liquid to walls of tower. Low efficiency. 

Liquid redistributors are required every 5-10 tower diameters with pall rings, and at least every 20ft for other types of dumped packings. The number of liquid streams should be 3-5/fF in towers larger than 3 ft diameter. Some experts advocate 9-12/ft [27]. 

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