Research On Dust-Control Method And Distribution Regularities Of The Uncontrolled Dust

Environment is becoming worse and worse, and dust pollution is one of the most serious problems. The uncontrolled dust produced by open dust emission source, with the characteristics of high dispersion degree, is difficult to control and easily influenced by natural climatic conditions (temperature, humidity, rainfall, wind speed, etc.). Under the action of the natural wind, this dust is more prone to pollute the surrounding environment, and taking dust-control method to control them is necessary. So it is important to research into the dust-control method and distribution regularities of the uncontrolled dust.This dissertation chooses the open stock yard and porous fence as its research objects which will be discussed with the theoretical analysis, numerical simulation method and experiment study. First, stress condition, dusting mechanism and movement locus are analysed on gas-solid two phase flow theory; then based on the actual atmospheric conditions, the simulation model of the natural flow's action on the stockpile is built to analyze and compare the flow field around the stockpile and the dust transport situation with or without the porous fence; according to the actual situation of open stock yards , the experiment model was built in the laboratory, where relevant datas were tested and analyzed; CFD simulate on model was proved by experimental results.Research results obtained:1,Numerical simulation analysis may identify: porous fence can reduce the wind speed effectively and reduce the turbulent kinetic energy of the coming flow, and the range size of the aerodynamic shadow zone which forms after the porous fence will influence the effects of the dust control directly. The influence of porous fence height on dust-control effect mainly displays that when the porous fence height below the stockpile height, the spread of dust will intensify ; when the porous fence height is greater than the stockpile height, dust-control effect will first increase and then decrease with the increasing porous fence height; the best height of porous fence is 1~1.5 times higher than stockpile height; the dust-control effects of porous fence under high wind condition is better than small wind condition.2,Numerical simulation results of dust transport situation shows: the dust on the surface of stockpile will move with coming flow under the action of wind, and in this process, some particles will slowly sedimentation, while the others will continue to move with suspended state. If without porous fence , the movement range of dust particles will be beyond 1000 meters in the downstream direction, however, after setting up porous fence, this situation is contolled well and high particles concentration area behind stockpile (downstream direction) is under control, the range of which is 2-3 times than the height of porous fence. Dust will be drawn into the vortex between stockpiles and its extent, and depends on the intensity of vortex, but this scope is limited in area between stockpile and the follow-up diffusion process would be unaffected.3,Through experimental observation, we can draw the following conclusions: if the porous fence is set in front of the stockpile in the coming flow direction ,it is obvious that the wind speed reaches up to 90% decline; the efficiency of the porous fence is good; if it is combined with the spray, the efficiency is even better. And comparing with the experimental results, it shows that the simulation model built in the paper has high accuracy.