Packed towers laboratory-size

The eflBciency of packed towers is generally expressed as the height equivalent to a theoretical plate. Most of the reported values of H.E.T.P. s are for small laboratory columns, since this is one of the largest uses of packed columns. H.E.T.P. is a function of the packing dimension and construction, tower size, vapor velocity, and system being rectified. The efficiency of packed towers may be seriously impaired by the liquid s tending to pass down one side while the vapor flows up the other. This channeling of vapor and liquid prevents effective interaction between the vapor and liquid. 

These data indicate that H.E.T.P. values as low as 1.5 in. have been obtained, making it possible to obtain the equivalent of a large number of theoretical plates in a relatively short height. Because of their efficiency and simplicity, packed towers are widely used for laboratory columns. However, when larger packed towers are used, the efficiency in general decreases, and H.E.T.P. values of a few feet are more common for columns of commercial size. 

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