Posted on November 18, 2020
Dr.ir. Sape A. Miedema
Educational Director MSc Offshore & Dredging Engineering Delft University of Technology
Delft University of Technology
Facilitator: Kathryn Thomas, Vice President, ANAMAR Environmental Consulting, Inc.
Monday, November 23, 2020
1:00 PM to 3:00 PM EST
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In deep-sea mining, the valuable materials will often be transported to the surface by means of slurry transport through pipelines, using centrifugal pumps to generate the pressure. The slurry transport pipeline has vertical, but also inclined trajectories. It is thus of interest what are the dominating factors in slurry transport in inclined pipes. Here this is investigated for Newtonian settling slurries. Experiments to investigate the dominating factors in slurry transport in inclined pipes were carried out in the CCCC National Engineering Research Center of Dredging Technology and Equipment, Shanghai, China. These experiments were carried out in a Dp=0.3 m pipe with sand with a d50 of 0.77 mm, concentrations up to 16%, inclination angles up to 44° and line speeds up to 7 m/s.
The physics of slurry transport can be divided into 5 main flow regimes. Each flow regime has its dominating physics. The stationary bed regime is based on bed friction, the sliding bed flow regime on sliding friction, the heterogeneous flow regime on collisions and collision intensity, the homogeneous flow regime on wall friction, and the sliding flow regime on sliding friction. So, each flow regime requires its own approach on how to deal with inclined pipes. Models in literature most often multiply the effect of the so-called solid with the cosine of the inclination angle, without considering different flow regimes, which is considered here as incorrect. Because different flow regimes respond differently, also the transitions between the flow regimes will depend on the inclination angle. It should be noted however that the potential energy term always dominates the hydraulic gradients measured.
Dr.ir. Sape A. Miedema (November 8th 1955) obtained his M.Sc. degree in Mechanical Engineering with honors at the Delft University of Technology (DUT) in 1983. He obtained his Ph.D. degree on research into the basics of soil cutting in relation with ship motions, in 1987. From 1987 to 1992 he was Assistant Professor at the chair of Dredging Technology. In 1992 and 1993 he was a member of the management board of Mechanical Engineering & Marine Technology of the DUT. In 1992 he became Associate Professor at the DUT with the chair of Dredging Technology. From 1996 to 2001 he was appointed Head of Studies of Mechanical Engineering and Marine Technology at the DUT, but still remaining Associate Professor of Dredging Engineering. In 2005 he was appointed Head of Studies of the MSc program of Offshore & Dredging Engineering and he is also still Associate Professor of Dredging Engineering. In 2013 he was also appointed as Head of Studies of the MSc program Marine Technology of the DUT.
Dr.ir. S.A. Miedema teaches (or has taught) courses on soil mechanics and soil cutting, pumps and slurry transport, hopper sedimentation and erosion, mechatronics, applied thermodynamics related to energy, drive system design principles, mooring systems, hydromechanics and mathematics. He is (or has been) also teaching at Hohai University, Changzhou, China, at Cantho University, Cantho Vietnam, at Petrovietnam University, Baria, Vietnam and different dredging companies in the Netherlands and the USA.
His research focuses on the mathematical modeling of dredging systems like, cutter suction dredges, hopper dredges, clamshell dredges, backhoe dredges and trenchers. The fundamental part of the research focuses on the cutting processes of sand, clay and rock, sedimentation processes in Trailing Suction Hopper Dredges and the associated erosion processes. Lately the research focuses on hyperbaric rock cutting in relation with deep sea mining and on hydraulic transport of solids/liquid settling slurries.
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