Study On Movement Characteristics Of The Falling Particle Stream Of Sloping Outflow

During the bulk transportation of industrial producing, the falling particle streams accompanied by a lot of dust during dispersion can often be seen. There is positive meaning to control dust generation in this process for the assurance of producing, the protection of worker, and the improvement of air quality. Controlling the dust diffusion through an energy efficient way could save resource while also reducing dust emission, thus responds to the national energy conservation. This paper explores the mechanism of dust generation, the diffusion law and the influencing factors of particle stream, so as to provide effective theoretical basis to reduce the ventilation energy consumption and improve the dust removal system efficiency.Based on the previous researches of group,this paper analysis the dust diffusion and movement of falling particle flow. In order to test the influence of mass flow rate, drop height, inclined angle and other factors to the ramp flow dust generation, this research uses alumina, aluminum fluoride, silica particles as falling materials, gets particle trajectory and the dust diffusion data near contact surface by means of using high-speed video camera and bench. Through the supporting software for photo analysis, the flow regime change and the spread of dust could be seen obviously. Moreover, this paper also studies the flow regime change and dust generation mechanism while the outflow way is different.Comparing the process of ramp particle flow and free-falling particle flow through experiment, mass flow, drop height, material type and contact surfaces could effect the dust generation. When the mass flow rate increases, the ramp flow dust generation rate increases while the dust generation rate of free-falling stream varies at different drop heights; with the increasing of drop height, the dust generation rate both increases; when the material type and contact surface is not the same, the dust generation rate is substantially the same. Using mathematical statistics analysis method, the relationship between the flow rate and the drop height, the mass flow rate and the inclined angle is analyzed,and the empirical formula between them is obtained.Through the photo analysis of particle falling and collision, there is a clear particle scattering in the opposite direction of particle flow during the process of falling; and during the process of collision, the particles diffusion on one side is more serious. In addition, this study also find that the particle flow rate increases as the particle mass flow rate increases, and the incremental particle velocity slows while the fall height increases.