Numerical Simulation Of Granular Mixing In Stirred Tank

As raw material and product of Chemical Engineering, Pharmaceutical, Metallurgy, Material Engineering, particle is widely used in the field of the former process industry. Generally speaking, granular mixing is one of the most important unit operation in the relative production engineering. During the mixing, the degree of mixing and the power consumed is the point. As one of numerical method to analyze the force acting on particle, DEM has become an efficient way for researchers working in process engineering. Because DEM can calculate the force exerted on particle when they just starting contact or collide. And we can attain all the dynamic information about all the particles in every time step.This paper works on the mixing of sphere particles in a standard elliptic sealed stirred tank. Through the Hertz-Mindlin and Linear Spring, we can calculate the force acting on the particle to gain the mixing of process of two kinds of particles under different impeller, rotational speed and weight of the particles, the diameter of which lies in 2-3mm and 4-5mm. At the same time, we employ real particle with same material and diameter span for the experiments of mixing under different fill level and rotational speed.When the rotational speed is 30rpm or 60rpm, the power of experiments agree well with the simulation. And we found that the single helical ribbon and double helical ribbon have potential on the mixing of particle clusters. At the same time, the revolution between start and steady state is same when in terms of same particles and impellers, and has nothing to with the rotational speed. And the outcome is 100 revolutions (double helical ribbon),170revolutions (Paravisc),60revolutions (single helical ribbon),190revolutions (Paravisc plus Pfaulder)? The macromixing of double helical ribbon is sensitive to the variation of rotational speed, however the other three is not.The radial position of particles of 2-3mm will stay 0-20mm after mixing and is not sensitive to the variation of rotational speed. The axial position is related to the impact of impellers, and the particles of r/R=0.25, 0.45,0.65,0.85 will go to the region of 200-250mm in most operational conditions involved in this paper.The experiments agree well with the simulation in the step of mixing. Additionally, the simulation not only provides torque, power and the degree of mixing, but also the information which is difficult, if not possible, to attain through the experiments.