Solid Suspension Characteristics in a Dished Base Tank for a Range of Geometric and Solids Properties

• Main Authors: Janurin, Nur Syafiqah, Ibrahim, Shaliza, Zamzam, Zauyah, Kato, Yoshikazu
• Format: Article
• Published: Society of Chemical Engineers, Japan 2018
• Subjects: TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.um.edu.my/21749/; https://doi.org/10.1252/jcej.17we026

Just-suspension conditions were studied in a dished base baffled cylindrical tank with internal diameter, T=155 mm using two variables of impeller-to-tank geometry, D=0.3T and 0.5T. The performance of the alternative geometries was studied using a conventional down-pumping 45° four pitched blade turbine (4PBT) impeller in comparison to the novel SATAKE SUPERMIX® HR100 and HS604 impellers. The slurry comprised of 18.0, 75.3 and 195.5 µm PMMA particles in concentrations ranging from 5–40% by weight. The performance of solid suspension was assessed in a dished base tank, which was found to be not as efficient as the flat base tank when used with the D=0.5T impellers. However, it is interesting to note that, when used with a suitable impeller, namely the HS604 impeller, the dished base tank was more superior to the flat base tank. This indicates that impeller-to-tank geometry is critical in determining the efficiency of solid suspension. Additionally, solid suspension performance in a dished base tank was markedly enhanced with D=0.3T impellers by approximately 60 to 80% reduction in the specific energy at just suspension (εjs) compared with D=0.5T, resulting from the fluid flow pattern generated inside the stirred tank. This suggests that the dished base tank is not a poor option for solid suspension if it is used with the right impeller geometry.