Study On Characteristics Of Air-operated Spraying And Dust Control Technology

Due to the complexity of crushing,transport,and screening in the coal preparation plant,dust control has been a main technical problem,which is also a common concern and key problem in the domestic and overseas advance.In order to effectively reduce the dust concentration of the handling system in coal preparation plant coal,this paper combined theoretical analysis,numerical simulation and experimental application to study dust transport rules and dust control technology,which forms a system of dust control in the handling system.Based on the large eddy simulation of gas turbulence,the subgrid turbulent energy model is proposed.At the same time,the interaction of particle fluctuating velocity and the particle phase linear multiscale Kp-?p turbulence model is considered,and the kinetic model of gas phase large eddy simulation and particle phase turbulence is build.Besides that,collision between particles and wall is considered.By the analysis for the force situation of particle,the dynamic model of particle is build.At the same time,we determined the motion state of 10?m,50?m and 100?m in the different eddy velocity.The formation mechanism of induced airflow and the diffusion rule of dust are described in the coal fall area,core area and collision area.Meanwhile,the airflow field and moving law of dust in different time and different cross section are simulated.Finally,we derived the relational expression of power function between the airdrop velocity,falling height and induced airflow.Through calculating the gridding technology of hydro mechanics and the discrete phase particle tracking technology was used to get the diffusion rule of particles in the process of coal conveying.The atomization process and atomization mechanism is expatiated deeply,and the two-phase flow in the nozzle and droplets in the eddy flow field is analyzed.Based on the collision model,breakup model and evaporation model,the results of impact on the spray model calculation is obtained by the spray process of grid number of calculation model,number of droplet and size of time step.We simulated the process of multi-nozzle interference and worked out the relationship of the crushing distance and atomizing angle along with pneumatic pressure.Characteristics of multi-nozzle interference is researched and the influence relationship of number of nozzle and velocity of droplet dust removal efficiency is obtained at the same time;The atomization effect is determined by the influence factors such as pneumatic pressure induced airflow and distance of nozzles.Then the basis of selecting nozzle parameters are determined.Dust monitoring and intelligent spray system and tail sealing cover which is applied in the Tashan coal preparation plant coal conveying system.The average dust concentration and respirable dust concentration of five points on the transfer point are 21.46 mg/m3 and 8.84 mg/m3,at the same time,the average dust fall rate reached 94.21%and 93.55%respectively,good dust suppression effect are obtained.It proves the practicability of combined inhibiting in dust monitoring and intelligent spray system.