Drag reduction in large diameter hydraulic capsule pipeline

This study is a second-stage continuance of a previous work on polymer drag reduction in Hydraulic Capsule Pipeline (HCP) flow using a 54 mm diameter pipeline loop. The primary mission of this study is to explore the potentials of polymer drag reduction in commercial HCP application. An existing recirculating closed-loop steel pipeline of 210 mm in diameter and 131 m long was employed in this study. Polyox (trade name for polyethylene oxide) was tested alone and in combination with fiber for the first time for drag reduction investigations in such a large diameter HCP flow. A novel design of vacuum-aided Polyox dissolution and injection system was also tested for the first time in this pipeline. The injected polymer concentration in the test section was determined numerically by a one-dimensional dispersion model calibrated to the experimental system using a fluorescent dye additive for experimental measurement. In addition, abrasion-resistant resin logs with cement additives for density control were employed to simulate coal logs.; Tests found Polyox is effective in drag reduction in the 210 mm diameter steel pipe of water flow. At the same polymer concentration and initial bulk fluid velocity, higher drag reduction was observed in this commercially-sized pipe, relative to the benefits observed in the previous 54 mm diameter pipe. Polymer drag reduction in HCP flow increases with increasing polymer concentration and initial bulk fluid velocity. A capsule-flow-based drag reduction of 66% is possible at polymer concentration of 24 parts-per-million (ppm) and an initial velocity of 2.65 m/s for capsule train of a = l.8, k = 0.92, S = 1.35. Higher drag reduction is expected at either high velocity or higher polymer concentration.; Wood pulp was found to be effective in enhancing polymer drag reduction in flow with capsules present, although no impact on drag reduction has been found when fiber was used alone or added to the pipeline with Polyox in flow without capsules present. In addition, mass production of Polyox concentrates becomes easy and effective under vacuum conditions without external mechanical disturbance. Further improvement of the designed Polyox tank has industrial implications.; Results of this study not only answered some basic questions about drag reduction in HCP flow, it is also beneficial and important to HCP commercial applications. A very important remaining question, which was unanswerable in the present existing test loop, is the ability of the Polyox to avoid degradation in realistic commercial applications.