Packing dumped

Ceramic and metal packings are normally dumped into the column wet , to ensure a truly random distribution and prevent damage to the packing. The column is partially filled with water and the packing dumped into the water. A height of water must be kept above the packing at all times. 

Tower packings are divided into three principal types those that are dumped at random into the tower, those that must be stacked by hand, and those known as structured or ordered packings. Dumped packings consist of units 6 to 75 mm I to 3 in.) in major dimension packings smaller than 25 mm are used mainly... 

Column sizing may include several types of trays, as sieves or valves, as well as several types of packing, dumped or structured. 

FIG. 14-80 Cost of internal devices for columns containing dumped packings, a) Holddown plates and support plates, (h) Redistributors, (c) Liquid distributors. [Pikulik and Diaz, Cbem. Eng., 84(21), 106 (Oct. 10, 1977).]... 

Once packing heights are determined in other sections from HETP (distillation) or Koa (absorption), the height allowances for the internals (from Figure 1) can be added to determine the overall column height. Column diameter is determined in sections on capacity and pressure drop for the selected packing (random dumped or structured). 

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. 

Tlie flood pressure drop for structured packing, already shown in the subsection on random dumped packings, is repeated here ... 

For stacked packing the liquid usually has little tendency to cross-distribute, and thus moves down the tower in the cross-sectional area that it enters. In the dumped condition most packings follow a conical distribution down the tower, with the apex of the cone at the liquid impingement point. After about 12 ft vertical height, the liquid flow s vertically downward unless redistributed. For uniform liquid flow and reduced channeling of gas and liquid with as efficient use of the packing bed as pos.sible, the impingement of the liquid onto the bed must be as uniform as possible. 

Dumping is the most common method of packing installation. If possible, the tower should be filled with... 

Metal and plastic packing can be dumped dry into the tower however, reasonable care must be exercised, and the drop should not be more than 10-15 ft, using a chute with a cloth sock (open) on the end to cushion the impact. 

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