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1. The absence of preliminary humidifying practically does not
influence the absorption and desorption processes at room temperature.
2. Because the humidifying is a very rapid process, the air is humidified
in the space under the packing and in the first half meter of the packing height.
3. The preliminary humidifying of the air with pure water leads to
reduction of the solution concentration in the experimental column because of
water vapour absorption. That is why the preliminary humidifying can be not
only without avail, but in some cases even harmful.
4. In the industrial columns, for the calculation of which the
experimental data are intended, preliminary humidifying of the gas phase is not
provided.

2,1.1.3. Construction of the experimental column
The experimental installations are two types, pilot plant installations
built to proof the apparatus suitability for a given industrial process, and
installations developed to obtain experimental data for the performance
characteristics of the packings. The date obtained in the latter type of
installations are used directly to design industrial columns, or to obtain
equations necessary for their designing. In this chapter only the second type of
installations is considered. They are proper for investigation of the following
performance characteristics of the packings:
- pressure drop;
- loading and flooding point;
- liquid holdup;
- effective surface area;
- gas- and liquid-side controlled mass transfer coefficient.
There are some important differences in the requirements to the
industrial and the experimental installations. The industrial columns are
designed to achieve, as cheap as possible, some important technological and
economical parameters, i.e. to take part in lower-cost production of high quality
products keeping ecological conformity. The experimental installation is
designed to obtain, as precisely as possible, the necessary data for calculation of
industrial columns.
The most important characteristics of the experimental installations are
column diameter, packing height, and liquid phase distributor construction.
To avoid the influence of the ratio of the column diameter to the
packing diameter, respectively its characteristic dimension, on the obtained
data, this ratio should not be lower than 8 [1]. The height of the packing should
be determined in every case, so that the accuracy of the results is the highest
The determination of the effective surface area and the mass transfer
coefficient is connected with chemical analysis of the initial and end