Page 290 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

280

In Fig. 60 the experimental data for the effective area of two
honeycomb packings made of sheets of thermopressed sintered porous PVC
[64] are presented. The packing is specially designed to operate at extremely
low liquid superficial velocity.

1 -#- L - • h
—r" _ J 1 ' •
0,8 U «r—* > "• =•«
< H —•—
-S3
:• o,6
1 • Packing No.1
0,4 • Packing No.2
I I I

0,8 1 6 8 10 20 40 60 80

Fig . 60. Ratio of effective to the specific surface of packings of thermopressed sintered porous
3
3
3
2
3
2
PVC: Packing No 1- a=189 m /m , S = 0.9 m /m , 4 = 19 mm; Packing No 2- o=360 m /m ,
3
3
S =0.83 m /m , dtr 9 mm.
It can be seen, that packing No 1 is practically completely wetted at
4
3
2
liquid superficial velocity about 7.10 m /(m s). At this liquid velocity the ratio
3
3
2
of effective to total surface of packing No 2 is about 0.78. At £=10' m /(m s) it
is about 0.8 and is not increasing with further increasing of L. The fact that the
effective area of this packing cannot reach the specific area is explained [64]
with the small packing hydraulic diameter at which the influence of the
thickness of the liquid film on the hydraulic diameter, respectively on the
3 3 2
effective surface area, is not to be eliminated. That is, at Z=10" m /(m s) this
packing is also completely wetted.
3.2,2.1.2.4. GaM-side controlled mass transfer coefficient of packings with
vertical smooth walls
To calculate the gas-side controlled mass transfer coefficient of
packings with vertical smooth walls, Zhavoronkov et al. [87] proposed the
following equation:
4
3
= 0.167 Re^ .S4' .(h/d ) - a47 (194)
h