Page 191 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

181

The value of the constant^ is determined experimentally. It is as
follows [245]:
for Raschig rings - $ = 0.6;
for Pall rings- ^ = 0J.
The comparison of the calculated data and the experimental ones shows
a significant disagreement in some cases. For example, for 12.5 mm Raschig
rings and system dichloroethanol-benzene, the difference is up to 2.5 times. For
the most of the experiments the difference is less than 30%.
Simplifying Eq. (27) and taking into account the influence of the liquid
superficial velocity on H4 according to Eqs. (79) and (80), Billet [177] proposed
the equation

Table 8. Geometrical characteristics of the packings investigated by Reichelt and used for testiog
of equations (25) and (26)
Sizes Diameter Free volume Specific Material Symbols
3
mm mm m /m 3 surface area
3
itftta
26.08x25.1x0.5 41.5 0.9® 127 Steel O
m § 0.962 155 •
15.4x15.1x0.5 41.5 0.933 277 Steel X
79J 0.024 314 A
11.85x12.05x0.3 41.5 0.944 377 Steel •
79.8 0.941 404 CD
e
139.0 0.939 416
8.5x8.05x0.3 41.5 0.921 494 Copper •
79.8 0.913 543
139.0 0.913 543 Q
15.95x1410x2.65 41.5 0.746 210 Porcelain »
79.8 0.698 250 O
9.73x10.06x1.685 41.5 0.6S5 437 Porcelain +
79.8 0.652 471 ©
139.0 0.655 475