Experimental Study On Solid-liquid Suspension Characteristics Of Propeller In Viscous System With High Solid Loading

The main purpose of solid-liquid mixing is to make the solid particles completely disperse in the stirred tank,and then increase the contact area,so as to accelerate the chemical reaction rate and strengthen the mass transfer and heat transfer efficiency.Most of the previous studies on solidliquid mixing were focus on dilute solid-liquid suspension in water system,however,in the practical production,the mixing system is always running at high solid loading with viscous fluid.For example,the mixing process for ore pulp during the smelting.Thus,in this paper,the solidliquid suspension characteristics of dense glass beads-maltose syrup system driven by Propeller were studied experimentally.First,the solid suspension characteristic of viscous system with high solid loading driven by Propeller was studied,and the power consumption of Propeller was taken as the index to evaluate the extent of the difficulty in suspending the solid.Results show that the unit mass power consumption at just off-bottom suspension condition is decreasing with the increase of solid concentration first,then decreasing.The solid conentration corresponding to the lowest value of unit mass power consumption is defined as the optimal solid concentration under the condition.The energy required to suspend solid of unit mass is the lowest when operating at this solid cocentration.Based on the definition of optimal solid concentration,the influence on optimal solid concentration under different parameters were compared and discussed in detail.Moreover,on the premise of the determination of the structure parameters,the correlation of the power consumption at just off-bottom suspension condition with the liquid density,the liquid viscosity,the density,concentration and size of particles is presented.It concludes that the correlation has good performance in predicting the optimum solid concentration well.Second,the solid distribution characteristic of viscous system with high solid loading driven by Propeller was studied in viscous system with high solid loading,and the uniformity of solid concentration distribution was taken as the index to evaluate the extent of the quality in suspending the solid.Results show that compared with the axial direction,the concentration gradient in the radial direction is negligible.Based on this,the structure parameters and material parameters on solid concentration distribution of axial direction were studied experimently.Results show that the uniformity of solid concentration distribution varies directly with liquid viscosity and total solid concentration at the same impeller speed.In order to quantify the mixing uniformity in the vessel,the mixing index of different conditions were calculated and analyzed,thus the suitable working conditions were determined.The solid suspension and distribution characteristics of viscous system with high loading driven by Propeller were systematically studied by using experimental methods.The influence of different parameters on the characteristics was obtained,which has guiding significance for industrial production.