Gas–liquid hydrodynamics in a vessel stirred by dual dislocated-blade Rushton impellers

Towards the objective of improving the gas dispersion performance, the dislocated-blade Rushton impeller was applied to the gas–liquid mixing in a baffled stirred vessel. The flow field, gas hold-up, dissolved oxygen, power consumption before and after gassing were studied using the computational fluid dynamics (CFD) technique. Dispersion of gas in the liquid was modelled using the Eulerian–Eulerian approach along with the dispersed k–ε turbulent model. Rotation of the impeller was simulated with the multiple reference frame method. A modified drag coefficient which includes the effect of turbulence was used to account for the momentum exchange. The predictions were compared with their counterparts of the standard Rushton impeller and were validated with the experimental results. It is concluded that the dislocated-blade Rushton impeller is superior to the standard Rushton impeller in the gas–liquid mixing operation, and the findings obtained here lay the basis of its application in process industries.

Graphical abstractWith the desire to improve the gas dispersion performance in stirred vessels, the standard Rushton impeller (SRT) was took placed by the dislocated-blade Rushton impeller (DRT), which has the advantage of improving the axial pumping capacity. The gas–liquid mixing processes were simulated with the combination of the Eulerian multiphase model and the dispersed k-ε model. Comparisons with the standard Rushton impeller indicate that the dislocated-blade Rushton impeller outperforms the former in the gas–liquid mixing operation.Figure optionsDownload full-size imageDownload as PowerPoint slide