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Effect of Near-Wall Turbulence on Selective Removal of Particles from Sand Beds Deposited in Pipelines

  • Author / Creator
    Zeinali, Hossein
  • A large-scale experimental facility was designed, constructed, and operated to study multiphase flow of solid-liquid mixtures (i.e., slurry flow) in horizontal pipelines. Trains of discrete lenticular deposits (LDs) and continuous beds were identified and studied in detail, representing two distinct forms of solids deposits occurring during horizontal pipeline flow of stratified slurries. The experimental results showed that LDs, which occur at relatively low flow velocities and solids concentrations, are identifiable and reproducible and are the stable pattern of slurry flow/transportation. Experiments were conducted to examine how near-wall turbulent structures (i.e., turbulent burst and sweep activity) are influenced by the geometry of bed deposits. Particle image velocimetry (PIV) was used to measure the near-wall (interface) velocity and turbulent activity. Turbulence structure in the vicinity of LDs and the continuous bed were observed, measured, and compared to near-wall turbulent structures of a glass pipe containing water only. It was found that naturally shaped LDs reduce the burst-sweep frequency and intensity compared to the continuous bed pattern, resulting in reduced production of turbulent kinetic energy. Experiments were also conducted to study the effect of near-wall turbulent activity (burst-sweep) on selective (size-dependent) removal of particles from beds with initially broad size distributions deposited in a 95-mm ID glass pipe. Deposit beds were formed using particles (i) predominantly smaller than 60 µm (Phillips domain), (ii) predominantly larger than 170 µm (Shields domain), (iii) intermediate in size between i and ii (intermediate domain), and (iv) of all sizes mixed together (poly-sized particles). For a bed containing predominantly Phillips-domain particle sizes, larger particles are preferentially removed, mainly because inter-particle attraction forces (e.g., van der Waals forces) dominate in this range. The fine particles are retained in the bed. However, for a bed of predominately Shields-domain particle sizes, the smaller particles are removed. In the intermediate region (60 < dp < 170 µm), particles are evenly exposed to the “updraft under a burst” force and are lifted into the bulk flow; therefore, the overall solids concentration decreases in this region. Results from poly-sized (mixed) particle experiments confirm the results for the individual domains.

  • Subjects / Keywords
  • Graduation date
    2012-09
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/R3S369
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
    English
  • Institution
    University of Alberta
  • Degree level
    Doctoral
  • Department
    • Department of Civil and Environmental Engineering
  • Specialization
    • Petroleum Engineering
  • Supervisor / co-supervisor and their department(s)
    • Dr. Peter Toma (Department of Civil and Environmental Engineering)
    • Dr. Ergun Kuru (Department of Civil and Environmental Engineering)
  • Examining committee members and their departments
    • Dr. Mengjiao Yu (the University of Tulsa Petroleum Engineering Department)
    • Dr. Zhenghe Xu (Department of Chemical and Materials Engineering)
    • Dr. Japan Trivedi (Department of Civil and Environmental Engineering)
    • Dr. Tayfun Babadagli (Department of Civil and Environmental Engineering)