Analysis of Pipeline Transportation Parameters for Medium-low Concentration Coal Gangue Slurry
Coal gangue is an important material for grouting in coal mining space.During the pipeline transportation process after crushing and slurry production,it faces problems such as sedimentation and blockage,friction loss,and pipeline pressure safety,which affect the efficiency of grouting.Based on the practice of grouting,a systematic study was conducted on the basic properties,fluid types,flow state,critical flow velocity,critical flow velocity,and pressure resistance of medium-low concentration coal gangue slurry(with a mass concentration less than 50%)in pipeline transportation.Through testing and analysis,it was found that the fluid type of medium-low concentration coal gangue slurry is Newtonian,and the flow state of pipeline slurry is generally in the turbulent hydraulic smooth zone-mixed friction zone.The critical flow rate was calculated under different slurry concentrations(volume concentration 0.16～0.22,solid particle size 0.15～1.18mm)(compared with FEI Xiangjun's formula and WASP's formula),with a value of 1.2～1.9m/s(pipeline inner diameter D=76mm).The frictional loss during slurry transportation essentially depends on the specific frictional resistance R(hydraulic slope),with the most sensitive factor being the pipe diameter(R∝D～5).Based on the actual slurry transportation of the Muduchaideng pipeline,it is believed that the risk of pipe blockage is low,the pipeline pressure meets safety requirements,and the theoretical value of specific friction resistance is consistent with the measured value.Meanwhile,considering the current high specific friction resistance,it is recommended to adjust the inner diameter of the pipeline from the current 76mm to 88mm or more,which can reduce the specific friction resistance by more than half.The research can be used to guide the design of pipeline transportation for medium-low concentration coal gangue slurry,providing theoretical basis for the safety and efficiency of pipeline transportation of slurry.
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