Two-phase Vertically Upward Transport of Silica Sands In Dilute Polymer Solution: Drag Reduction And Effects of Sand Size And Concentration

An experiment of a 2-phase vertically upward hydraulic transport of silica sands in the dilute polymer solution Xanvis L in a pipe is conducted to investigate the effects of a polymer additive, silica-sand particle size and concentration on pressure gradient Δp/L or drag. The sand particles are in 3 sizes: 8∼10, 30∼40 and 80∼100 mesh (2.36∼2.00, 0.6∼0.425, 0.180∼0.150 mm). The concentration ranges are from 2.2% to 9.3%, and the flow loop is made of a clear PVC pipe 2.54 cm in diameter. Pressure drops and average flow rates were measured in the Reynolds number range of 104 < Re < 105. Flows in a dilute polymer solution significantly reduce the Δp/L or drag of water-sand mixture flows in the higher Reynolds-number range, where drag or Δp/L reduction is as much as 60%. In the lower Re range, however, the Δp/L for the mixture flows either with or without the polymer additives becomes larger than the flows of water without the sand mixture. Higher drag reduction or lower Δp/L occurs at the higher Re range, while drag gradually increases with the lower Re over flows of water alone (without the mixture and additives.) The trend of the drag increase over water alone with a polymer additive over the flows without starts at the higher Re values with the increase of the concentration. The conventional perception is that the smaller the particles, the smaller the drag or Δp/L. Instead, the measured Δp/L values for the 80∼100-mesh finer sand particles are larger than those of the larger 30∼40 mesh sands.