engleski

An Experimental Investigation into the Complete Drawdown of Floating Solids in Dual-Impeller Stirred Vessels

Experimental work is reported on the drawdown of floating solids by mechanically agitated vessel with multiple impellers. The main aim of this work was to study the effect of different types of dual-impeller systems on the achievement of the complete suspension state of floating solids. Previous investigations on this topic have been limited to single-impeller systems only. In the present work three types of impeller were employed: three-bladed 30o pitched turbine down-flow (3-PTD), four-bladed 45o pitched turbine down-flow (4-PTD), and straight blade turbine (SBT). Tap water and polyethylene particles (PEHD) were used as liquid and solid phase, respectively. The effects of physical properties of suspension as well as the impacts of a number of geometrical variables of the systems on the critical impeller speed and power consumption were studied in detail. The results indicate that the appropriate location of the second impeller on the same shaft can improve the performance of the agitation system for the process of floating solids suspension. This improvement is noted through decrease of FrJS and (P/m)JS values. For all dual-impeller systems examined, the correlations for the estimation of the minimum impeller speed to attain the just dispersed state of floating solid particles has been developed.

Mixing; suspension; floating solids; dual-impeller system; complete drawdown

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