Page 288 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

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Table 27. Geometrical characteristics of the packings investigated by Nakov [166]
Packing Material Specific area. Equiv, diam. Element height Void
a 4 k fraction
2
m /m 3 m m £
m'/rn 3
PQ-58 polystyrene 187 0.020 0.058 0.94
PP polypropylene 185 0.018 0.031 0.83
PK 27-20 ceramics 103 0.030 0.023 0.75
PK 27-40 ceramics 97 0.031 0.040 0.74
PK 27-60 ceramics 96 0.031 0.060 0.75
PK 20-20 ceramics 167 0.0186 0.021 0.73
PK 20-40 ceramics 154 0.020 0.040 0.76
PK 20-60 ceramics 153 0.020 0.060 0.75

The investigations are carried out using the method of Van Krevelen et
al. [282], The absorption of NH3 in water- sugar solution of H2SO4 is used as a
model system. The liquid viscosity and density are varied between 1 and 10.3
3
mPa.s, and 1000-1274 kg/m respectively. In all experiments the gas velocity is
1 m/s.
The influence of liquid superficial velocity on the ratio of the effective
to the total area for lie ceramic packing P27-60 is presented in Fig. 59.
From both figures it is to be seen that at a given critical liquid
superficial velocity L c, characteristic for every packing and viscosity, the ratio
(a/a) remains constant, equal to 1. For calculation of L c, Nakov [166] presented
the following equations:

for plastic packings

(190)

for ceramic packings

(191)