Power Consumption in Agitated Vessels with Dual Rushton Turbines: Baffle Length and Impeller Spacing Effects

Abstract

The dependence of power consumption on baffle length, L, in vessels agitated by a dual Rushton turbine system was studied within the turbulent regime, and also in relation to the impeller spacing, DH. A dependence of varying strength could be observed. The presence of baffles in the agitated systems provided a stabilizing effect with regard to the dependence of the Newton number Ne on the Reynolds number Re. A sharp decrease in power consumption could be detected for baffle lengths L < 0.3 H, with H the liquid height in the vessel. The Newton number was not significantly affected by L in the range 0.3 H < L< 0.5 H. For L > 0.5 H a sharp increase in Ne with increasing L could be observed. The two Rushton turbines act independently at DH > 1.65 d, with d being the impeller diameter. As the baffle length decreased, an increased mutual interaction between the two impellers could be observed for a broad regime of DH/d values. Ne was not affected by DH for the unbaffled agitated systems studied.

Prediction of drop sizes for liquid–liquid systems in stirred slim reactors—Part I: Single stage impellers

“…Towards higher immersion depths, the increase of Ne over baffle length again leads to a stronger growing power consumption. Such results with sigmoidal behavior have been reported in literature for single Rushton turbines [34] as well as dual Rushton turbines [36]. The results of this study have been approximated for both types of baffles with a cubic equation:…”

Influence of Spacing of Multiple Impellers on Power Input in an Industrial‐Scale Aerated Stirred Tank Reactor

“…It is used to describe the hydrodynamic behavior. The power number is reportedly not affected by spacing of the stirrers in unbaffled systems , .…”

“…is defined by the dynamic viscosity h. It is used to describe the hydrodynamic behavior. The power number is reportedly not affected by spacing of the stirrers in unbaffled systems [30,31]. Gas-liquid reactors equipped with multiple impellers ensure a higher efficiency of gas utilization and a longer retention time [21].…”

Flow Field Analysis of Stirred Liquid‐Liquid Systems in Slim Reactors

“…For a triple Rushton turbine, the correlation between mixing time and baffle width was h 95~b -0. 33 . Both cases showed a dependency for the number of baffles as follows: h 95~nB -0.…”

“…The investigations aim to complete the power analyses that have already been carried out by the authors for slim reactors [1,31] [32] as well as for dual Rushton turbines [33]. This physically expected behavior is excellently predicted by the CFD simulations for the standard RCI.…”