Numerical Simulation And Experimental Study Of Solid-liquid Suspension Two-phase Flow Field In Horizontal Double Shaft Agitating Equipment

Petroleum pollutants enter the soil through various ways in the process of exploration,development,transportation and refining,resulting in soil and groundwater pollution.The solvent extraction process is widely used in the remediation of oil-contaminated soils.The key to this process is the soil homogenization effect of mechanical agitating equipment.Several types of horizontal agitating equipment were designed in this paper.The characteristics of solid-liquid suspension flow field inside different types of agitating equipment were compared and analyzed by numerical simulation and internal flow field experiments.Firstly,horizontal single shaft and double shaft agitating equipment were designed according to the standard NB/T 47042-2014 “horizontal container”.The soil homogenization performance of different types of equipment was evaluated by numerical simulation.The results showed that the soil homogenization effect of the two devices was enhanced with the increase of the agitator speed.The horizontal double shaft agitating equipment has obvious advantages for soil homogenization.When the homogenization effect is similar,the static structure of the double shaft mixing device is more stable than the single shaft.So it is determined that the horizontal double shaft agitating equipment is used for soil homogenization.Subsequently,the mathematical model of solid-liquid suspension of the horizontal double shaft agitating equipment was used to study the influence of different soil treatment capacities,the type of impeller and the rotational speed of impeller on the flow field characteristics.And the mechanical characteristics of the stirring device were analyzed based on the fluid-structure coupling method.The results show that with the increase of the stirring speed,the solid-liquid suspension effect is enhanced,but the stress and strain of the stirring device increase.Compared with the pitched blade type,the lower tangential speed of the shovel style agitator is conducive to solid-liquid mixing.And the overall performance is better.When the rotational speed is 30 r/min and solid mass fraction is 60%,the solid-liquid mixing is relatively uniform under the action of the shovel style impeller(the angle between the blade and the axial direction is30°).The static structure of the stirring device is relatively stable.Finally,with the help of two-dimensional PIV and high-speed photography experiments,the flow field characteristics of the horizontal double shaft agitating equipment were further studied.Experiments show that with the increase of the agitator speed,the soil particle distribution becomes more uniform.The velocity of the flow field around the agitator increases.When the rotation speed is 30 r/min,the mixing effect is better at the shovel agitator(the angle between the blade and the axial direction is 30°),which is consistent with the simulation results.