The Evaluation of the Mixing Properties of the Mechanically Stirred Cylindrical Vessel

Ito, Kimihisa; Yamamoto, Norihiro; Kuranaga, Seiichiro

doi:10.2355/isijinternational.46.1791

Cited by 14 publications

(10 citation statements)

References 7 publications

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“…5) For mechanical stirring operation, Nakai et al 6) showed that desulfurization rate increased remarkably when vortex caused by mechanical stirring came at the impeller position and the flux dispersed in steel melt. There are also studies of the effect of baffles 7,8) on the dispersion behavior 9,10) of particles into liquid in a mechanically agitated bath.…”

Section: Introductionmentioning

confidence: 99%

Liquid/liquid Mixing Pattern in a Mechanically-stirred Vessel

et al. 2014

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In order to find out effect of operating factors on mixing pattern which affects liquid/liquid mass transfer rate drastically, cold model experiment was carried out with liquid paraffin or tetradecane as a dispersed phase and ion-exchanged water as a continuous phase in a mechanically stirred vessel. There exist three types of liquid/liquid mixing pattern in a mechanical agitation. I: region where each liquid phase separates and has no dispersion, II: region where vortex of dispersed phase (liquid/liquid interface) arrives at impeller position and its dispersion begins into continuous phase, III: region where gas/liquid interface as well as liquid/liquid one arrives at impeller position and dispersion occurs heavily. The transition of I-II accelerated along with the increases in rotation speed, ratio of dispersion phase volume to continuous one, density of dispersion phase, impeller diameter and vessel diameter, and the decrease in impeller depth. The transition of II-III accelerated along with the increases in rotation speed, density of dispersion phase and impeller diameter, and the decrease in impeller depth. The multi regression equation for the transition of I-II is expressed as, , where H: distance between free surface of oil and upper part of impeller (mm), Hoil: bath depth of dispersed phase(mm), N: rotation speed(rpm), Voil/Vw: ratio of dispersion phase volume to continuous one(-), di: impeller diameter(mm). D: vessel diameter(mm), ρd: density of dispersion phase(kg/m 3), whereas that on transition of II-III is H ∝ N 2.18 di 1.96 ρd 1.33 .

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Section: Introductionmentioning

confidence: 99%

Liquid/liquid Mixing Pattern in a Mechanically-stirred Vessel

et al. 2014

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“…[2][3][4][5][6][7][8] On the other hand, authors carried out the cold model experiment on solid/liquid mixing pattern, 9) which was clarified into three types as well as liquid/liquid one. 10) Figure 1 shows the categorized three types of solid/liquid mixing pattern.…”

Section: Introductionmentioning

confidence: 99%

Solid/liquid Mass Transfer Correlated to Mixing Pattern in a Mechanically-stirred Vessel

et al. 2014

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Cold model experiment on ion-exchange reaction between pearlite particles and HCl aq. was carried out in order to understand the effect of particles dispersion and operating factors on solid/liquid mass transfer rate in a mechanically-stirred vessel. Inner diameter of vessel was varied in conjunction with both bath depth as 400 (base) and 300 mm. Rotation speed and volume ratio of particles to liquid were changed between 0-240 rpm, 0.02-0.24 (-), respectively.When rotating speed increased, solid/liquid mass transfer rate increased moderately both in the regions I and III, whereas it increased in the region II. When impeller depth decreased, it was kept almost constant in the region I, increased in the region II and increased moderately in the region III. Solid/liquid mass transfer rate changed less than liquid/liquid one in the region II when rotation speed and impeller height were changed, whereas both of solid/liquid and liquid/liquid mass transfer rates were kept almost constant in the region I. The dimensionless equation on solid/liquid mass transfer rate of each region was given as a function of Sherwood number, Reynolds number, volume ratio of particles to liquid and bath depth normalized by vessel diameter. Dispersion ratio in the region II was ranged by solid/liquid mass transfer coefficient and rotation speed or impeller height of the transitions I-II and II-III. Solid/liquid mass transfer rate of mechanical stirring was larger than that of gas injection practice for the same supplied rate of energy into bath.

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“…Thus, many studies on mechanical stirring practice have been conducted. Kuroyanagi et al 5) and Ito et al 6) showed effect of baffles on solid/liquid stirring, and Sukawa et al 7) and Nomura et al 8) clarified a behavior of particle dispersion in water. Observing solid/liquid flow patterns by cold model experiment, Nakai et al 9) divided the behavior of particle dispersion into three stages, (1): the stage where a vortex does not arrive at impeller position and has no dispersion in liquid, (2): the stage where a vortex bottom exists between top and bottom of the impeller and particles begin to disperse into liquid, and (3): the stage where a vortex bottom attains at the position deeper than the impeller and there has complete dispersion in liquid.…”

Section: Introductionmentioning

confidence: 99%

Mass Transfer between Different Phases in a Mechanically-stirred Vessel and its Comparison with that in a Gas-stirred One

et al. 2014

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In order to understand effect of operating conditions on mass transfer between different phases in a mechanically stirred vessel, cold model study was carried out with liquid paraffin as a dispersion phase and ion-exchanged water as a continuous phase. Inner diameter of vessel, D, was varied in conjunction with both depth, H0, as D=H0=400 and 300 mm. Rotation speed, N, was changed between 50-240 rpm, volume ratio, Voil/Vw, of dispersed to continuous phase was 5.9×10-2 and 1.2×10 -1 . Liquid/liquid mass transfer rate showed characteristic trend depending on liquid/liquid mixing pattern. It was kept nearly constant at lower level in the region I, monotonically increased in the region II except near the region III and its increasing rate decreased in the region II near the region III. Liquid/liquid mixing pattern was grouped into three regimes. I: the region where liquid/liquid interface did not arrive at the impeller, II: the region where liquid/liquid interface attained at impeller position, III: the region where gas/liquid interface touched impeller.Under the same supply rate of mixing energy, liquid/liquid mass transfer rate of mechanical stirring corresponded to that of gas stirring at a point in the region II. In the region I and the first half of II, liquid/ liquid mass transfer rate of gas stirring is larger than that of mechanical stirring, whereas that of gas stirring is smaller than that of mechanical stirring in the region III and the latter half of II.Gas/liquid mass transfer rate increased remarkably with an increase in N in the region III.

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The Evaluation of the Mixing Properties of the Mechanically Stirred Cylindrical Vessel

Cited by 14 publications

References 7 publications

Liquid/liquid Mixing Pattern in a Mechanically-stirred Vessel

Liquid/liquid Mixing Pattern in a Mechanically-stirred Vessel

Solid/liquid Mass Transfer Correlated to Mixing Pattern in a Mechanically-stirred Vessel

Mass Transfer between Different Phases in a Mechanically-stirred Vessel and its Comparison with that in a Gas-stirred One

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