Experimental and computational study of multiple impeller flows

Harvey, Albert D.; Wood, Stewart; Leng, Douglas E.

doi:10.1016/s0009-2509(96)00462-9

Cited by 43 publications

(24 citation statements)

References 9 publications

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“…At discrete, evenly spaced locations along each arc, the velocity is interpolated from the computational grid and averaged to yield a &averaged velocity value at the corresponding grid point on the interpolation grid. The O-averaged velocity field obtained using this averaging procedure has been shown to agree well with time-averaged velocity data obtained using LDV (Harvey et al, 1995(Harvey et al, , 1996 and is equivalent to a time-averaging procedure when the baffles are removed. mesh will intersect the impeller stack at a different location at each time increment.…”

Section: Discussionsupporting

confidence: 60%

“…Extracting information useful in making reactor design decisions is not a trivial task. Harvey et al (1995Harvey et al ( , 1996 measured the time-average velocity in a constant &plane inside the stirred tank for single-and multiple-impeller configurations, respectively. In order to compare the numerical results to these measurements, a circumferential or &averaging procedure is performed on the computed three-dimensional velocity field.…”

Section: Discussionmentioning

confidence: 99%

“…For multiple impellers the assembly of grid zones consisting of the impeller zones couched between the upper and lower zones are stacked end-to-end in the axial direction. Detailed computations for the analysis of the flow in multiple-impeller-stirred tanks are presented in Harvey et al (1996).…”

Section: Multiple Impelkr Constructionmentioning

confidence: 99%

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Steady and unsteady computation of impeller‐stirred reactors

Harvey

Rogers

1996

AIChE Journal

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Section: Discussionsupporting

confidence: 60%

Section: Discussionmentioning

confidence: 99%

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Steady and unsteady computation of impeller‐stirred reactors

Harvey

Rogers

1996

AIChE Journal

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“…These interactions are greatly affected by the parameters like impeller diameter and spacing [10], leading to different gas dispersion performances in stirred tanks. In large scale industrial gas-liquid reactors, the manufacturing and operational costs are closely related to the optimal design of the impeller, especially the diameter of impellers.…”

Section: Introductionmentioning

confidence: 99%

Influence of impeller diameter on overall gas dispersion properties in a sparged multi-impeller stirred tank

Bao

Wang

Ming-li

et al. 2015

Chinese Journal of Chemical Engineering

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Relative power demand CFD Multi-impeller stirred tankThe impeller configuration with a six parabolic blade disk turbine below two down-pumping hydrofoil propellers, identified as PDT + 2CBY, was used in this study. The effect of the impeller diameter D, ranging from 0.30T to 0.40T (T as the tank diameter), on gas dispersion in a stirred tank of 0.48 m diameter was investigated by experimental and CFD simulation methods. Power consumption and total gas holdup were measured for the same impeller configuration PDT + 2CBY with four different D/T. Results show that with D/T increases from 0.30 to 0.40, the relative power demand (RPD) in a gas-liquid system decreases slightly. At low superficial gas velocity V S of 0.0078 m·s −1 , the gas holdup increases evidently with the increase of D/T. However, at high superficial gas velocity, the system with D/T = 0.33 gets a good balance between the gas recirculation and liquid shearing rate, which resulted in the highest gas holdup among four different D/T. CFD simulation based on the two-fluid model along with the Population Balance Model (PBM) was used to investigate the effect of impeller diameter on the gas dispersion. The power consumption and total gas holdup predicted by CFD simulation were in reasonable agreement with the experimental data.

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“…[4] These advantages make these systems attractive for many industrial applications, and there is a great potential for process optimization and intensification. [5] Previous experimental studies on multiple-impeller systems have focused on impeller spacing, [6] off-bottom clearance and impeller type for their power number, power consumption, gas hold-up, gas-liquid mass transfer, [7] effect of baffling on fluid mixing [8] and mixing time. [9] Computational fluid dynamic (CFD) studies have been used to model gas residence time distribution (RTD), [10] liquid phase flow, [11,12] just suspension speed, [13,14] particle distribution, [15,16] particle suspension characteristics, [17,18] flow regimes, [19] power consumption, [20,21] gas phase flooding characteristics, [22] flow patterns [23] and mixing time.…”

Section: Introductionmentioning

confidence: 99%

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

See

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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Experimental and computational study of multiple impeller flows

Cited by 43 publications

References 9 publications

Steady and unsteady computation of impeller‐stirred reactors

Steady and unsteady computation of impeller‐stirred reactors

Influence of impeller diameter on overall gas dispersion properties in a sparged multi-impeller stirred tank

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

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