CFD analysis of industrial multi-staged stirred vessels

Alliet-Gaubert, Marion; Sardeing, Rodolphe; Xuereb, Catherine; Hobbes, Phillippe; Letellier, Bertrand; Swaels, Philippe

doi:10.1016/j.cep.2005.11.003

Cited by 43 publications

(24 citation statements)

References 16 publications

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“…The second group presents local indicators such as velocity profiles, streamlines and particles tracking. Statistical methods such as probability density function of stretching [20] were not used in this work.…”

Section: Flow Characterization Tools and Methodsmentioning

confidence: 99%

“…The axial flow rate, Q ax , at different heights in the vessel is evaluated by the surface integration of either the positive, v +z , or negative, v −z , component of the axial velocity at particular horizontal plane: [20] (15) Where A is the radial section of the tank.…”

Section: Axial Flow Number and Average Axial Circulation Timementioning

confidence: 99%

“…In mixing, the flow regime is characterized by the Reynolds number, Re, defined in agitated tank as [20]: (14) Where D is the impeller diameter (in m) and N is the rotational speed (rpm) where ρ is the liquid density (kg m −3 ).…”

Section: Powermentioning

confidence: 99%

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Experimental and computational fluid dynamics modeling of mixing by Visco-jet impellers

Rahimi

Amraei

Alsairafi

2011

Korean J. Chem. Eng.

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This paper reports experimental and computational frluid dynamics (CFD) studies on an impeller called Visco-jet with the aim of finding the effect of two side diameters ratio of its blade, which has a semi-conical shape, on drawdown process of floating polymericparticles into high viscosity glycerin solution. Nine different geometries were examined experimentally, and there were significant differences in their performance. The results reveal that when diameter of smaller side of semi-cone impeller is half of the other side, mixing was performed in a more efficient way. The CFD-predicted results have been used for explaining the experimental observation. The CFD-predicted hydrodynamics parameters confirm superiority of this geometry compared with the other ones.

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Section: Flow Characterization Tools and Methodsmentioning

confidence: 99%

Section: Axial Flow Number and Average Axial Circulation Timementioning

confidence: 99%

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Experimental and computational fluid dynamics modeling of mixing by Visco-jet impellers

Rahimi

Amraei

Alsairafi

2011

Korean J. Chem. Eng.

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“…Based on this range of the impeller speed, the value of Re number varied from 40 to 80, which can establish a transient flow regime close to laminar. Regarding studies done by Kelly and Gigas [20] and Alliet-Gaubert et al [14], the macro-instabilities that may happen at this transient flow regime can be neglected, so the flow was assumed laminar. In addition, a convergence criterion of 10 −7 was chosen for all calculated parameters.…”

Section: Modeling Strategymentioning

confidence: 99%

“…They explained the numerical methodology and compared the results of the simulation with experimental data in the case of a tank stirred with a helical ribbon. In another study, CFD modeling was used by Alliet-Gaubert et al [14] for single-phase flows in multi-stage stirred vessels for two industrial cases. In that study, various methods for results analysis to get a good mixing characterization were collected and the applications of those methods were specified.…”

Section: Introductionmentioning

confidence: 99%

Experimental and computational fluid dynamic (CFD) studies on mixing characteristics of a modified helical ribbon impeller

Rahimi

Kakekhani

Alsairafi

2010

Korean J. Chem. Eng.

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Experimental and computational fluid dynamic (CFD) modeling studies have been performed on mixing characteristics of a new modified helical ribbon impeller in a viscous medium. A novel arrangement for the multiple reference frame (MRF) technique was proposed and the modeling results were compared with those of conventional MRF selecting method. Calculations were performed to study the effects of several parameters: axial flow number, axial circulation time, impeller clearance, and power consumption. The higher performance of the modified impeller has been proven in terms of axial flow number and axial circulation time. The results showed that significant improvement in mixing performance can be obtained at a higher impeller clearance with the modified impeller employed. In addition, the power consumption by the new impeller has been compared with that of the classic one. The CFDpredicted flow patterns generated by the impellers were used to explain the higher performance of the modified impeller. In addition, the results reveal that the CFD-predicted particle volume fractions at various axial distances from the tank bottom are reasonably in agreement with the experimental observations.

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Study of sparger location on solid suspension in a triple‐impeller stirred vessel

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Raman

Shah

et al. 2015

Asia-Pacific J Chem Eng

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Several advantages such as good gas and solids dispersion have been associated with triple-impeller system for three phase mixing processes. In this work, minimum impeller speed required for achieving just suspended condition was studied with gassing using three Rushton turbines as agitators. The effects of sparger location and gas flow rate on the just suspension speed, gas hold-up, gas-liquid mass transfer coefficient and power consumption were discussed. Sparger placed above the bottom impeller showed the highest gas hold-up at just suspended condition with the same total power consumption as the other two sparger locations. The highest gas hold-up value achieved was 12% at total power consumption of 370 W. The data obtained fitted well into ΔN js = kQ g with k = 3.67 when the sparger is located below the bottom impeller. Significantly lower k values can be obtained when the sparger is shifted above the bottom impeller. The sparger location above the bottom-most impeller is proposed to be superior for industrial application of aerated solid suspensions where at least 8% saving on power consumption can be achieved.

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CFD analysis of industrial multi-staged stirred vessels

Cited by 43 publications

References 16 publications

Experimental and computational fluid dynamics modeling of mixing by Visco-jet impellers

Experimental and computational fluid dynamics modeling of mixing by Visco-jet impellers

Experimental and computational fluid dynamic (CFD) studies on mixing characteristics of a modified helical ribbon impeller

Study of sparger location on solid suspension in a triple‐impeller stirred vessel

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