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

Abstract

The power consumed in mechanically agitated vessels is an important parameter, especially for the energy requirements and the heat and mass transfer efficiencies of these systems. Power consumption does not only depend on the impeller type, the fluid properties and the stirring speed, but also on the geometry of the agitated system, including the impeller spacing and the length of the baffles in the mixing vessel. Information is presented on the combined effects of baffle length and impeller spacing on the total power consumption in vessels agitated by dual pitched blade impellers.

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

“…where H L is the height of liquid in the reactor . Independent behavior of impellers has been reported for pitched blade turbines in tap water as starting with a spacing of 1.55 d , while for two Rushton turbines it has been reported to start at a greater spacing of 1.65 d , , . For small gas flow rates, a sharp increase in Po is reported for dual Rushton turbines for spacing in the range of 0.6 to 0.8 d , which is much smaller for higher gas flow rates .…”

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

Application of a Capillary Microreactor for Selective Hydrogenation of α,β-Unsaturated Aldehydes in Aqueous Multiphase Catalysis

“…To underline this thesis, theoretic activation energies should be measured again with smaller-scaled capillaries, which should yield higher values because microkinetics gets more involved in the overall reaction rate. As already shown by Roberts [14], mass transport limitation can also strongly influence the selectivity in parallel reactions provided that the reaction order of the substrate is different. Unfortunately, this effect could not be observed in the presented model reaction systems.…”

Influence of Different Baffle Variations on the Effectiveness of Multi‐Stage Agitated Vessels

“…So beträgt der Formfaktor für Flachstromstörer c F = 1 und ist für davon abweichende Formen annähernd das Verhältnis aus dem Widerstandsbeiwert einer angeströmten Platte zu dem entsprechenden Bauteil. Aufgrund der Reduzierung der Umfangskomponente der Strömungsgeschwindigkeit durch die Stromstörer kommt es im turbulenten Bereich mit zunehmender Bewehrung zu einem Anstieg der Newton‐Zahl des Rührers . Nach Liepe et al erreicht die Newton‐Zahl bei genügend hoher Bewehrung einen Maximalwert und bleibt dann, auch bei größer werdenden Bewehrungskennzahlen, konstant.…”