W.P.M. Van Swaaij

Bio: W.P.M. Van Swaaij is an academic researcher from Royal Dutch Shell. The author has contributed to research in topics: Shear rate & Shear stress. The author has an hindex of 1, co-authored 1 publications receiving 59 citations.

Vertical pneumatic conveying: An experimental study with particles in the intermediate and turbulent flow regimes

Abstract: Vertical pneumatic conveying was studied in a 3-inch diameter riser 30 feet in length using solids ranging in particle Reynolds number from 100 to 3500. Particle to gas mass flow ratios varied from 0 to 8 and pipeline conditions extended from dilute flow down into the choking region. Average particle hold-up was determined by means of a series of quick-closing valves and particle slip velocity was often found to be greater than the calculated terminal velocity. The reasons for this are examined. Frictional pressure losses in the riser were also determined and compared with literature data. The phenomenon of choking is considered briefly. On a etudie le transport pneumatique et vertical, dans un tuyau de 30 pieds de longueur et 3 pouces de diametre, en utilisant des matieres solides dont les nombres de Reynolds des particules variaient entre 100 et 3500. Les rapports d'ecoulement entre les particules et le gaz variaient de 0 a 8 et les conditions dans le tuyau se sont etendues d'un ecoulement dilue a la region d'engorgeinent. On a determine la retention moyenne des particules, au moyen d'une serie de soupapes qui fermaient rapidement, et l'on a souvent trouve que la velocite de glissement etait plus elevee que la velocite terminate qu'on avait calculee; on en analyse les raisons. On a aussi determine les pertes de pression dues a la friction dans le tuyau et les a comparees avec les donnees publiees. On considere brievement le phenomene d'engorgement.

Situating the high‐density circulating fluidized bed

Abstract: Gas-solid flow in high-density circulating fluidized-bed risers differs significantly from that in conventional flow regimes, including fast fluidization and pneumatic conveying. It is shown that where there is no downward flux at the wall at high suspension densities, and hence no core/annulus structure, the flow corresponds to a dense suspension upflow regime. This flow regime is explained, and its key properties given. A lower boundary is also proposed for this new flow regime based on available data.

Axial and radial solids distribution in a long and high‐flux CFB riser

Abstract: Radial solids concentration profiles were determined with a fiber-optic probe on eight axial levels in a 76-mm-ID, 10-m riser, at solids flux (solids circulation rate) up to 550 kg/m2·s and superficial gas velocity up to 10 m/s Radial concentration profiles at high solids fluxes of over 300 kg/m2·s are less uniform than lower fluxes of less than 200 kg/m2·s Under all operating conditions, the flow development in the riser center is nearly instant, with the solids concentration remaining low at the riser center throughout the riser In the wall region, increasing solids flux significantly slows down the flow development, with the solids concentration near the wall decreasing all the way toward the riser top at high fluxes In the high-flux circulating fluidized bed (HFCFB), a middle section with intermediate solids holdups of about 7 to 20% was between the bottom dense section and top dilute section, with its length increasing as the solids circulation rate increases and as the gas velocity decreases Flow conditions in this section resemble those of the dense suspension upflow under high-density operating conditions by Grace et al (1999) When its length extends to the riser top, a high-density circulating fluidized bed for which an HFCFB is a necessary but not a sufficient condition, forms