Page 279 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

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where fi is an experimental constant depending on the type and dimension of
the packing and on the physical properties of the liquid phase.
Ramm und Sakgeim [159] used this equation to correlate their own
experimental data obtained at low liquid superficial velocities, up to 4.7x10" 3
3 2
m /(m s), and obtained that for all their packings fi = 52.5 s/m. It is possible to
describe the data for packings with different dimensions using only one value of
/? because at the values of £ at which the investigation of Ramm und Sakgeim
[159] is carried out AP/AP 0 is close to 1 and the error from incorrect taking
into account the irrigation influence is not very big.
The theoretical model of Zhavoronkov et al. [33] (Eq. (259) in Chapter
1) for taking into account the influence of the irrigation on the pressure drop,
and the equation (260) of Kolev [34], Chapter 1, for the pressure drop over the
loading point can be used together with Eqs. (165) and (166), [160]. In this case
for calculating Ag and AA, the following equations are proposed [160].

-0-OSS EU>.37-,-2.47 fines
.Fr L e (175)

IM
4
M = 3.4SxlO- ,[(^-f f /(d )J IM .( m
/(g.d h)J .(—f f
^
h
s s
(176)
u7
r f*»
The average deviation of the experimental date from those calculated
with Eq. (259) in Chapter 1 and Eq. (175) is 10%, and from those with Eqs.
(259) and (260) in Chapter 1 and Eqs. (175) and (176) over the loading point-
20%.
It is shown [160] that by using Eqs. (46), (175) and (176), the loading
point of a packing with vertical walls can be calculated. In this case the value of
the constant Kk is also 1.03.
The model of Zhavoronkov et al. [33], Eq. (259), Chapter 1, considers
the channels in the packing as tubes with constant cross-sections. That is,
theoretically it cannot be used together with Eq. (170) which takes into account
the changing of the cross-section.
The irrigated packing pressure drop under the loading point must be
described [163] with equation of two terms, first for the channel with a constant
cross-section, and second for the local pressure drop. Taking into account, that
the liquid holdup changes not only the free cross-section in the channels of the