Page 275 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

265

A precise evaluation of the two components of the pressure drop was
associated with computations being rather heavy in 1969, when equations (165)
and (166) were published. On the other hand, experimental data for that time
were rather well described by Eqs, (165) and (166). For this reason, any further
studies on the separate constituents of the total pressure drop were considered
inexpedient for the moment [160].
In order to obtain a single equation able to predict the pressure drop of
arranged packings with vertical walls, it was necessary to obtain additional
experimental data including the values of the dimensionless parameters that had
not been studied before.
The geometrical parameters of the new packings [163] are listed in
Table 26.
The experiments were carried out in a column with a rectangular cross-
section 224 x 174 mm. Packing elements of the same size formed rows placed
one over the other. The pressure drop was measured with U-tube differential
manometer. Values below 10 mm WG were registered with a differential
manometer equipped with an optical system and a micrometric screw (precision
0.1 Pa).
The dry packing pressure drop AP 0 was presented as a sum of two terms
- pressure drop in the straight section (the rows) AP af and local pressure drop
between the rows AP oi:

(167)
AP o = AP ¥+AP oh

By analogy with a straight tube, AP^cnn be expressed by:

AT> — 3 WpPa /1£&\

where the friction coefficient Xi depends on the Reynolds number.
The local pressure drop in the packing AP 0[ is described by the
expression:

%% . (169)
h 2e