Image Analysis-based Experimental Study And DEM Simulation Of Particle Mixing Process In Rotating Cylinders

In the modern industry, rotary drum is widely used in large industrial processequipments, such as rotary kiln, drum drying machine, the ball mill, the coating machine,which are applied in non-ferrous metallugy, mining, chemical engineering, cement,refractories and food industries, and play an extremely important role in the country’seconomic development. The motion characteristics of the material in the rotary drum, such asmixing speed and mixed degree of the material particles directly affect energy transferprocesses, product quality and production efficiency. Therefore, the study on the mixingprocess of material in the rotary drum is of high theoretical and practical value.In the paper,the experimental rotating cylinder is applied to simulate the industrial rotarykiln. Professional image processing and analysis software Image-Pro Plus6.0is used tomonitor and analyze the particle mixing process in the rotating cylinder, the concentrationvariance in multiple fixed area and the mixing time are introduced to quantitatively describethe particle mixed degree and mixing speed, and the influence of different rotation speeds andfill degrees on the particle mixing process are investigated. The DEM(Discrete ElementMethod) numerical simulation model is established based on experiment to predict theparticle mixing process in the rotating cylinder and the simulation accuracy of the linearcontact model and the Hertz contact model are compared. The influence of rotation speedsand fill degrees are compared with the experimental data and the agreement is satisfactory.Finally the influence of different drum radius on the particle mixing process is simulated.The experiment and simulation studies demonstrate that the particle mixing speedincreases with the rotation speed. The mixing time is hence shorter, but the change of mixeddegree with the rotation speed is not obvious. With the increase of the fill degree, the time ofthe convection and the shear mixing process is slightly extended. With the increase of the filldegree the mixing speed slows down and the mixed degree slightly deepens. With theincrease of the drum radius, the mixing speed keeps approximately constant in the convectionmixed phase. However the mixing speed accelerates slightly in the convection shearinteraction stage until to the steady state where the mixed degree deepened. The experimental analysis and numerical simulation results in this paper provide animportant basis for the theoretical modeling of the movement of materials process and for thedesign and control optimization of the drum-formed kind industrial process equipment.