Page 100 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

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Chapter 2

Investigation of the main performance
characteristics of packed bed columns

The chemical engineering couples together theory and experiment to
calculate the industrial apparatuses. For obtaining the necessary experimental
data, special installations are used. These installations can be dividing in two
types:
1. Installation for obtaining the information necessary for deriving
equations for calculation of the performance characteristics (cold stand).
2. Rectification installation (hot stand) for obtaining experimental data
for comparison of different packings.
Of course, in the first type of installations also data for comparison of
different packings can be obtained. In the second type the pressure drop, the
holdup, and the HTU, respectively HTP, data can be measured.
A good development of the theory of mass transfer processes, together
with creating of apparatuses able to operate under conditions of uniform
distribution of both phases over the cross-section, enabled calculation of the
apparatuses based on the knowledge obtained only in the first type of
installations. The second type was necessary when the calculation, in all cases
based only on the data obtained in the first type, was not possible. Nevertheless,
the second type is also considered at least because it is a part of the history of
the investigations in this area and especially because the capital investments in
rectification plants are very great and need reliability assurance.

2,1, Investigations in cold stand

2.1.1. Experimental installations

The experimental installations of this type must include the following:
- Column for investigation of the packing;
- Pump and ventilator for feeding the gas and the liquid phase;
- Measurement devices for the flow rate, the concentrations of the
phases, and the pressure drop.