Improved mixing performance of gas-liquid stirred tanks by using V-shaped punched baffles

Background: It has been shown that the V-shaped punched baffle can enhance the fluid mixing in a single-phase stirred tank in our previous work, while its application in gas-liquid systems has not been investigated.Methods: Experiments on macro-mixing and computational fluid dynamics (CFD) simulation were carried out in an air-water system to compare the performance of standard baffle (SB), one-section V-shaped punched baffle (VSPB-1), two-section V-shaped punched baffle (VSPB-2) and three-section V-shaped punched baffle (VSPB-3). Significant findings: The simulation results indicate that the V-shaped punched baffle can not only generate impinging jet streams, but also increase the homogeneity of gas dispersion and the turbulence in the baffle re-gion, resulting in a better mixing performance. The experimental results demonstrate that the use of V-shaped baffles, especially VSPB-2 and VSPB-3, can effectively enhance fluid mixing at high impeller speeds. Moreover, VSPB-2 has the best effect with Rushton turbine (RT), and all V-shaped punched baffles have better effect with up-pumping pitched turbine (PTU) at different gas flow rates. With increasing impeller speed, the trend of decreasing mixing time for the four baffles is the same for RT and PTU. However, with increasing gas flow rate, the performance of the baffles is different.