An absorption study of an idealized packed column
Taylor, Byron N
Master of Science
An experimental apparatus was developed for the absorption of carbon dioxide into a falling layer of pure water. The liquid height of transfer unit, HtL, for the experimental apparatus in theory closely approximates the HtL for a packed absorption tower which was derived by Davidson(9) by considering a random angle, fixed length statistical model for the random packing in the tower. Data was obtained with the experimental apparatus for the purpose of testing the assumptions used by Davidson(9) in formulating his equation for HtL, for a packed tower. The results suggest that the assumption of perfect mixing between the liquid surface and the liquid bulk when the liquid flows from one piece of packing to another in a column may not be justified. Rippling on the liquid surface, which was neglected in the mathematical model for a packed tower, may serve to counter balance the effect of incomplete mixing between the elements. Since rippling probably occurs over the majority of packing at moderate flow rates in a packed column, Davidson's(9) statistical model equation can be expected to be a reasonable mathematical representation for absorption in a packed tower. Davidson's(9) other proposed statistical models for packed towers similarly should hold fairly well. The best choice between his random angle-fixed length, and his random anglerandom length, or his vertical surfaces models is made difficult by the effect of rippling which is known only in a qualitative way.