Power characteristics of unsteadily forward-reverse rotating impellers in an unbaffled aerated agitated vessel

Power characteristics of an unbaffled aerated agitated vessel with unsteadi ly forward-reverse rotating impellers, ie a new type of gas-liquid agitator named 'AJITER', treating viscous Newtonian liquids were studied experiment ally. Measurements were first made on the agitation torque, ie the torque o n the drive shaft on which forward-reverse rotating impellers with four del ta-type blades were attached, and the data obtained were analyzed by fittin g them to an equation consisting of two terms with respect to the resistanc e of the fluid, one due to viscous drag and the other due to added moment o f inertia. The effects of operating conditions and physical properties of l iquids on the drag and added moment of inertia coefficients were then evalu ated, and empirical relationships which estimate values of these coefficien ts, useful to predict the unsteady behavior and magnitude of agitation torq ue, were presented. Furthermore, equations were developed for estimating th e average and maximum power consumptions as a function of the drag and adde d moment of inertia coefficients. Prediction of respective power levels in AJITER by these equations was also discussed. (C) 2001 Society of Chemical Industry.