Title: Utjecaj tipa miješala na karakteristike raspršenja plina u kapljevini
Abstract: Gas dispersion in liquid is applied in a range of industrial processes in which mass transfer between these two phases is required. It is often carried out in mechanically agitated vessels. It is the geometrical characteristics of the vessel, primarily the type of mixer, that will determine the hydrodynamic conditions in the system, which directly affect the intensity of the mass transfer from the gaseous to the liquid phase (or vice versa). The main task of this research was to examine the influence of impeller types on the characteristics of gas dispersion in liquid. Experiments were conducted in a mixing vessel of 10,85 dm 3 volume. Two types of impellers were used: a concave-blade turbine with disk and a flat-blade turbine with disk. Firstly, agitator speeds at which different flow regimes are achieved were determined. The Froude and the aeration numbers at those flow regimes were calculated. Experimental aeration numbers were compared with theoretical values. Secondly, the relative power demand for different agitator speed was determined. This parameter is one of the most important parameters for assessing the economic viability of the process. Finally, based on the measurement of the concentration of dissolved oxygen in liquid, volumetric oxygen transfer coefficient, k L a, and the oxygen transfer rate from air into water were determined. By comparing the two types of impellers used, it was found that higher values of oxygen transfer rate are achieved by using the flat-blade turbine with disk, but with a higher power demand. Considering the stated, this impeller can be considered a more appropriate option if the primary goal of the operation is to achieve higher oxygen flow rates in the system.
Publication Year: 2021
Publication Date: 2021-03-31
Language: en
Type: dissertation
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