In order to study particle segregation in the rotating drum,the movement of particles is studied by theoretical deduction and numerical simulation.According to the theoretical deduction,particles near the end wall are...In order to study particle segregation in the rotating drum,the movement of particles is studied by theoretical deduction and numerical simulation.According to the theoretical deduction,particles near the end wall are lifted higher by the friction of the end wall,which leads to small particles gathering in the middle of the drum.The model of particle motion is established based on the discrete element method.It can be shown from the simulation results that the particles accumulated highernear the end w al,which is consistent with the theoretical deduction.In addition,the effects from the aspects of te relative friction between particles,the friction between the end wall a d particle,the drum aspect ratio and the rotation speed were explored by thesimulation.From the simulation results,it can be pointed out that the friction of the eed w a i has a decisive influence on the axial segregation of theparticles,and the other factors merely affect the accumulate forms of particles.展开更多
This study developed a theoretical approach to understanding how a set amount of a granular bed is discharged from a tilted rotary kiln （an empty cylinder） once its particle size distribution （PSD） is known and sl...This study developed a theoretical approach to understanding how a set amount of a granular bed is discharged from a tilted rotary kiln （an empty cylinder） once its particle size distribution （PSD） is known and slumping motion occurs. The basis of the study is that the preparation of material for thermal treat- ment inside a rotary kiln （pyrolysis, gasification, and]or combustion） involves shredding to a desired particle size. Further mechanical stress results from the feeder screws moving material from storage toward the reactor. The most common PSDs found in uniform size reduction processes and mechanical stresses are Gaussian, log-normal, and Rosin-Rammler, of which the latter best fits the PSD in our study. Different particle diameters in the distribution result in an axial segregation when a slumping motion occurs, resulting in particles of different diameters leaving the kiln at different instants. After develop- ing the model, the theoretical data showed good agreement when compared with experimental results obtained from downloading previously shredded carbonaceous material from a rotary kiln at 2 and 4 rpm rotational speeds. The mean residence times at steady state were determined for both rotational speeds and showed good agreement with data provided in the literature.展开更多
基金The National Natural Science Foundation of China(No.51775109)Jiangsu Science and Technology Support Plan Project(No.BE2014142)
文摘In order to study particle segregation in the rotating drum,the movement of particles is studied by theoretical deduction and numerical simulation.According to the theoretical deduction,particles near the end wall are lifted higher by the friction of the end wall,which leads to small particles gathering in the middle of the drum.The model of particle motion is established based on the discrete element method.It can be shown from the simulation results that the particles accumulated highernear the end w al,which is consistent with the theoretical deduction.In addition,the effects from the aspects of te relative friction between particles,the friction between the end wall a d particle,the drum aspect ratio and the rotation speed were explored by thesimulation.From the simulation results,it can be pointed out that the friction of the eed w a i has a decisive influence on the axial segregation of theparticles,and the other factors merely affect the accumulate forms of particles.
文摘This study developed a theoretical approach to understanding how a set amount of a granular bed is discharged from a tilted rotary kiln （an empty cylinder） once its particle size distribution （PSD） is known and slumping motion occurs. The basis of the study is that the preparation of material for thermal treat- ment inside a rotary kiln （pyrolysis, gasification, and]or combustion） involves shredding to a desired particle size. Further mechanical stress results from the feeder screws moving material from storage toward the reactor. The most common PSDs found in uniform size reduction processes and mechanical stresses are Gaussian, log-normal, and Rosin-Rammler, of which the latter best fits the PSD in our study. Different particle diameters in the distribution result in an axial segregation when a slumping motion occurs, resulting in particles of different diameters leaving the kiln at different instants. After develop- ing the model, the theoretical data showed good agreement when compared with experimental results obtained from downloading previously shredded carbonaceous material from a rotary kiln at 2 and 4 rpm rotational speeds. The mean residence times at steady state were determined for both rotational speeds and showed good agreement with data provided in the literature.
