https://doi.org/10.1007/s11356-022-20859-x
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Figure 11 shows the lines of gas flow through a packing rotating at 900 rpm. Based on the obtained results, it can be observed that at the gas inlet to the rotor, the gas entrainment effect is noticeable, which causes a slight bending of the flow trajectory due to gas inertia. This, however, does not extend the gas residence time inside the rotating packing. Further, the gas moves radially through the packing to the outlet. The rest of the investigated variants show the same pattern of gas flow streamlines through the packing. What is more, with increasing rotational speed of the packing, air velocity at the inlet to the packing increases and the entrainment effect is stronger.
Gas flow lines in the RPB device for the rotor speed of 900 rpm and the volumetric gas flow rate of 60 m3 h-1
The effect of the influence of rotation on the hydrodynamics of gas flow through the rotating bed and the related pressure drops can be described by means of CFD calculations. The pressure drops caused by the bed will increase with the addition of the liquid phase. It is therefore essential to check for dry pressure drops in order to select the fan in advance or determine the optimal gas flow parameters.
The high pressure drop inside the rotating packing causes the gas velocity gradients to equalize along the bed radius (Figure 12). This effect minimizes the asymmetry of the device caused by the side location of the gas inlet. Although the gas is introduced parallel to the axis of rotation, it quickly gains angular velocity and rotates in the absorber housing. As a result of inertia, the air swirls leaving the absorber, which is visible by the formation of a low velocity zone in the axis of the gas outlet (absorber center). Such strong swirling of the gas in the center of the absorber can prevent effective spraying of liquid onto the bed during operation of the RPB apparatus. Therefore, it is necessary to find a range of operational parameters in which, as a result of rotation, the liquid will be well distributed over the bed and the interfacial exchange surface developed to the maximum while minimizing the gas pressure drops in the device.
Comparison of gas velocity distributions inside the RPB device for three selected rotor speeds of 600, 1200 and 1800 rpm. The volumetric gas flow rate of 40 m3 h-1
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