Improved Mixing in a Magnetite Iron Ore Tank via Swirl Flow: Lab-Scale and Full-Scale Studies

An experimental investigation on the fluid flow mixing process in agitated vessel

The fluid mixing process is a common supportive phenomenon that often occurs in a large number of industrial systems. This phenomenon is the subject of many numerical and experimental analysis. The mixing process effectiveness depends on: mixing tank construction, mixing phases viscosity, temperature, density of liquids and, what is crucial, the impeller shape. The optimal design of impeller geometry is still an open issue. In this research work, the main objective is experimental investigations of the influence of the newly constructed impeller type on the fluid flow motion phenomena and energy consumption. Flow field values were evaluated using PIV measurement and the power consumption using precise torquemeter. The comparison between the Rushton turbine and a novel impeller is presented and discussed. The basis for the assessment of the intensity degree and efficiency of mixing was the analysis of velocity vectors distribution and power number. Results show that the power number for both impellers are similar but the fluid motion is quite different. The pumping capacity Qz for the novel impeller in reference to the Rushton turbine is for many cases at least one order of magnitude higher. This shows that the proposed impeller can be a very promising alternative to the classic blades and non-blades based impeller types.

Effect of Impeller Design on Power Characteristics and Newtonian Fluids Mixing Efficiency in a Mechanically Agitated Vessel at Low Reynolds Numbers

The mixing process is a widespread phenomenon, which plays an essential role among a large number of industrial processes. The effectiveness of mixing depends on the state of mixed phases, temperature, viscosity and density of liquids, mutual solubility of mixed fluids, type of stirrer, and, what is the most critical property, the shape of the impeller. In the present research, the objective was to investigate the Newtonian fluids flow motion as well as all essential parameters for the mechanically agitated vessel with a new impeller type. The velocity field, the power number, and the pumping capacity values were determined using computer simulation and experimental measurements. The basis for the assessment of the intensity degree and the efficiency of mixing had to do with the analysis of the distribution of velocity vectors and the power number. An experimental and numerical study was carried out for various stirred process parameters and for fluids whose viscosity ranged from low to very high in order to determine optimal conditions for the mixing process.