Conditions Should Be Met of Particles in Rotary Kiln

Although the axial dispersion model (ADM) used to describe the movement process of the material in the rotary kiln can get some useful results, particle trajectory model descriptions starting from the granular dynamics is closer to reality for the movement of the materials with strong granulation in the rotary kiln. The particle trajectory model geometry is evolved from the idea of the single particle trajectory geometry simplified analysis. After the development of many scholars, random PTM model is formed to predict the average residence time of the material, the axial diffusion constant and other methods. The principles of the random PTM numerical simulation are the followings. Introduce a certain number of tracer particles in steady-state operation at the inlet end of the rotary kiln and calculate the total residence time of each particle in the kiln. At last, statistically analyze the residence time distribution for all the particles to get an average residence time and the variance, which respectively reflects the axial transport of the material in the rotary kiln and axial diffusion.
You should assume that the movement of the bed particles in the kiln can meet the following conditions. First, the bed particles are the spherical particles with uniform size but without viscid rigid body. The bed surface is a planar. There is no unevenness caused by unevenness due to the movement of materials. Second, the movement of the bad particles in the rotary kiln is composed of n repeated cycles. Each cycle is composed of the tumble process of the materials in the active layer of the surface of the material bed and the particle circular motion in the inactive layer. Third, the thickness of the active layer is very thin. The mutual movement between the material particles occurs only in the surface of the material bed surface. There is no mutual movement of the particles in the non-active layer. The axial displacement of the material particles only occurs only on the surface of the material bed, which has nothing to do with the circular motion of the particles in the inactive layer. Forth, the air in the rotary kiln has no impact on the bed particles.