Effect of Near-Wall Turbulence on Selective Removal of Particles from Sand Beds Deposited in Pipelines Open Access
- Other title
particle size distribution
- Type of item
- Degree grantor
University of Alberta
- Author or creator
- Supervisor and department
Dr. Peter Toma (Department of Civil and Environmental Engineering)
Dr. Ergun Kuru (Department of Civil and Environmental Engineering)
- Examining committee member and department
Dr. Tayfun Babadagli (Department of Civil and Environmental Engineering)
Dr. Zhenghe Xu (Department of Chemical and Materials Engineering)
Dr. Japan Trivedi (Department of Civil and Environmental Engineering)
Dr. Mengjiao Yu (the University of Tulsa Petroleum Engineering Department)
Department of Civil and Environmental Engineering
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
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.
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- Citation for previous publication
Zeinali, H., Toma, P., and Kuru, E., 2012, "Effect of near-Wall Turbulence on Selective Removal of Particles from Sand Beds Deposited in Pipelines," Journal of Energy Resources Technology, 134(2), pp. 021003.Zeinali, H., Toma, P., and Kuru, E., 2009, "Near-Wall Turbulent Transport Knowledge for Suitable Flow Assurance Strategies," ASME Conference Proceedings, 2009(43475), pp. 575-582.
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