Western Dredging Association’s next webinar will taka place on Monday, November 23, 2020 from 1 to 3 PM EST, and will be presented by and feature Dr.ir. Sape A. Miedema’s paper, “Dominating Factors in Slurry Transport in Inclined Pipes”.
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.
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.