Chemical Engineering Research and Design, cilt.202, ss.327-335, 2024 (SCI-Expanded)
At high solids concentrations (>2 vol%), a clear interface appears between solid-rich and liquid-rich parts of a solid-liquid mixing tank. The height of this interface is known as cloud height. The cloud height is one of the key design parameters; therefore, accurate prediction of it plays a critical role in the design of solid-liquid mixing tanks. This study proposes an empirical model that predicts cloud height as a function of particle properties, solids concentration (XV), off-bottom clearance, and impeller speed. Experiments were performed in a tall tank (H=1.5 T) agitated with a 45° down-pumping PBT. The model was tested against two independent data sets. It successfully predicts the cloud height for XV between 2 to 8 vol% and off-bottom clearance between T/6 to T/3. The size and the density of the particles were varied between 123 to 712 µm and 2500 to 7600 kg/m3, respectively. A modified version of the model was also proposed for high solids concentrations.