Page 283 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

273

3.2.2.1.2.2. Dynamic holdup of packings with vertical smooth walls
For arranged rings and pipes, Gildenblat [66-68] proposed the equation:

-0.14

1
which is proved for values of —— between 0.01 and 0.1 kg.nf'.s" .
a
The form of equation (168) is used by Kolev and Elenkov [77] to
predict the liquid holdup with Eq. (24) for arranged packings. In this case the
value of <p is given by the equation:

4.2-^ , (182)

where h is the height of the packing elements in m.
The equation described with an average error + 5% the date for 11
different packings with vertical walls. The values of the geometrical parameters
3
2
are changed as follows: h - from 15 to 100 mm; a- from 48.5 to 370 m /m and
3 3
e- from 0.55 to 0.77 m /m .
For calculation of the dynamic holdup of packings with vertical smooth
walls under the loading point, the following equation is also obtained [164]:

0J3 J4 0JI 49
H M =3.15(l-£)- .Frj> GaJ (a.h)-°- . (183)

The experimental constants in Eq. (183) are obtained based on data for
the packings presented in Table 26. For determining the influence of the
viscosity of the liquid phase, the experiments are performed with pure water and
3
water solutions of sugar or glycerine. The viscosity is changed from 10' to
3
9.10" Pa.s and the density from 1000 to 1160 kg/ml The liquid superficial
2
3
velocity varies from 3.10-3 to 2.10-2 m /(m s).
The arithmetical mean error of Eq. (183) is 16.4% and the maximal
error is 39.5%. It is seen that the experimental data are not described
satisfactory by Eq. (183). One of the reasons might be not accounting for
important sides of the phenomenon when deriving the equation. In the real
arranged packing with vertical walls, there are two types of surfaces the liquid