Height structured packing element

Use of HTU and K a Data In estimating the size of a commercial gas absorber or liquid stripper it is desirable to have data on the overall mass-transfer coefficients (or heights of transfer units) for the system of interest, and at the desired conditions of temperature, pressure, solute concentration, and fluid velocities. Such data should best be obtained in an apparatus of pilot-plant or semiworks size to avoid the abnormalities of scale-up. Within the packing category, there are both random and ordered (structured) packing elements. Physical characteristics of these devices will be described later. 

The angle of rotation and the element height therefore affect the extent of vapor and liquid spread in a structured packing. For this reason, element height is relatively short (typically 6 to 12 in) and the angle of rotation is around 90°. 

Depth of plastic random packings may be limited by the deformability of the packing elements to 10-15 ft. For metal random packings, this height can be 20-25 ft. For both random and structured packings, the height between redistributors is limited to 20-25 ft. because of the tendency of the phases to maldistribute. 

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