Critical impeller speed for solid suspension in turbine agitated contactors

The present study in solid-liquid contactors, an attempt has been made to calculate the minimum/critical impeller speed required for complete suspension of solids. A new correlation, involving Reynolds number, modified Froude number, along with the agitation characteristics is proposed. The effect of impeller geometry as well as impeller clearance are clearly established for 6-blade (flat) turbine agitated contactors.List of Symbols B Solid weight fraction (%) - c Clearance of the impeller from the tank bottom (m) - d_P Average particle size(m) - d_R Impeller diameter (m) - d_T Vessel diameter (m) - g Acceleration due to gravity m/sec₂ - N_cs Critical impeller speed (S^–1)Greek Letters Kinematic viscosity m²/sec - _L Density of liquid kg/m³ - _S Density of solid kg/m³ - Density difference between solid and liquid kg/m³