Effect of impeller design on liquid phase mixing in mechanically agitated reactors

Rewatkar, V. B. ; Joshi, J. B. (1991) Effect of impeller design on liquid phase mixing in mechanically agitated reactors Chemical Engineering Communications, 102 (1). pp. 1-33. ISSN 0098-6445

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Official URL: http://www.tandfonline.com/doi/abs/10.1080/0098644...

Related URL: http://dx.doi.org/10.1080/00986449108910846


Liquid phase mixing time (θmix) was measured in mechanically agitated contactors of internal diameter 0.57 m, 1.0 m and 1.5 m. Tap water was used as the liquid phase. The impeller speed was varied in the range of 0.4-9.0 r/s. Three types of impellers, namely disc turbine (DT), pitched blade downflow turbine (PTD) and pitched-blade upflow turbine (PTU) were employed. The ratio of impeller diameter to vessel diameter (D/T) and the ratio of impeller blade width to impeller diameter (W/D) were varied over a wide range. The effects of impeller clearance from the tank bottom (C), the blade angle (φ), the number of blades (nb), the blade thickness (k) and the total liquid height (H/T) were studied in detail. Mixing time was measured using the conductivity method. Mixing time was found to have a strong dependance on the flow pattern generated by the impeller. Mixing time was found to decrease by decreasing the impeller clearance in the case of DT and PTU. However in the case of PTD it increases with a decrease in the impeller clearance. Similar trend of the effect of impeller clearance on θmix, was observed for all the other PTD impellers with different diameter, number of blades and blade angle (except 60° and 90°). All the impeller designs were compared on the basis of power consumption and on this basis optimum design recommendations have been made. For PTD impellers, a correlation has been developed for the dimensionless mixing time.

Item Type:Article
Source:Copyright of this article belongs to Taylor and Francis Group.
Keywords:Mixing Time; Flow Pattern and Pumping Capacity; Pitched Bladed Turbine; Impeller Geometry; Optimum Impeller Design
ID Code:61168
Deposited On:13 Sep 2011 10:52
Last Modified:13 Sep 2011 10:52

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