stripping (redirected from hand stripping)

stripping [′strip·iŋ]

(chemical engineering)

In petroleum refining, the removal (by flash evaporation or steam-induced vaporation) of the more volatile components from a cut or fraction; used to raise the flash point of kerosine, gas oil, or lubricating oil.

(graphic arts)

In offset lithography, the process of positioning negatives or positives on a flat before making plates.

(metallurgy)

Removing a coating from the surface of a metal.

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Stripping

The removal of volatile component from a liquid by vaporization. The stripping operation is an important step in many industrial processes which employ absorption to purify gases and to recover valuable components from the vapor phase. In such processes, the rich solution from the absorption step must be stripped in order to permit recovery of the absorbed solute and recycle of the solvent. See Gas absorption operations

Stripping may be accomplished by pressure reduction, the application of heat, or the use of an inert gas (stripping vapor). Many processes employ a combination of all three; that is, after absorption at elevated pressure, the solvent is flashed to atmospheric pressure, heated, and admitted into a stripping column which is provided with a bottom heater (reboiler). Solvent vapor generated in the rebolier or inert gas injected at the bottom of the column serves as stripping vapor which rises countercurrently to the downflowing solvent. When steam is used as stripping vapor for a system not miscible with water, the process is called steam stripping.

In addition to its use in conjunction with gas absorption, the term stripping is also used quite generally in technical fields to denote the removal of one or more components from a mixed system. Such usage covers (1) the distillation operation which takes place in a distilling column in the zone below the feed point, (2) the extraction of one or more components from a liquid by contact with a solvent liquid, (3) the removal of organic or metal coatings from solid surfaces, and (4) the removal of color from dyed fabrics. See Electroplating of metals, Solvent extraction