Gas Flow Behavior in a Two‐Phase Reactor Stirred with Triple Turbines

Majirova, H; Pinelli, Davide; Machoň, Václav; Magelli, Franco

doi:10.1002/ceat.200401989

Cited by 10 publications

(6 citation statements)

References 18 publications

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“…Though the scope of this study, it is also interesting to mention that the Peclet values (equal to 1/a) determined with the regression technique based on Eq. (29) are obviously in good agreement with those obtained by considering only the ascending part of the experimental RTD curve, e.g., Majírová et al [10].…”

Section: Discussionsupporting

confidence: 72%

“…On the contrary, Svihla et al [9], who modeled the system with three ideally mixed stages with superimposed plug flow, concluded that the gas hold-up in a stirred vessel cannot be determined with satisfactory accuracy from the measurement of gas RTD even when using a tracer of very low solubility. Nocentini et al [4,5], Pinelli and Magelli [6], Majírová et al [10] and Linek et al [11] all adopted the axial dispersion model for modeling the gas phase, which proved quite accurate in predicting its behavior. Only the ascending part of the RTD curve was used by the first authors to determine the model parameter as the tail was affected by tracer solubility, while the whole curve was used by Linek et al [11] who employed a tracer of lower solubility (helium).…”

Section: Introductionmentioning

confidence: 98%

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Gas Hold‐Up Evaluation Using the Analytical Solution of the Axial Dispersion Model: Comparison with Static Measurement Results

et al. 2007

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A comparison was made of the gas hold-up values obtained in an aerated mixing vessel of high aspect ratio by both visual measurement of the liquid level rise due to aeration, agitation and processing, and the residence time distribution (RTD) curves of the gas flowing in the vessel. For the description of the RTD curves, the one-dimensional dispersion model with Danckwerts' boundary conditions was adopted and the corresponding equations were solved analytically. Experiments have been performed with both coalescent and non-coalescent systems. It was found that gas hold-up values determined with these two methods are in very good agreement. This also provides additional support for the use of the proposed model.

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Section: Discussionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 98%

Gas Hold‐Up Evaluation Using the Analytical Solution of the Axial Dispersion Model: Comparison with Static Measurement Results

et al. 2007

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“…Although the presence of small quantities of SDS is expected to somewhat decrease the maximum stable bubble size (due to the reduction of static surface tension), this tendency is counteracted by the tendency to impede bubble breakage due to the development of the Marangoni elastic forces . On the other hand, bubble coalescence rate is strongly hindered by the presence of very small SDS concentrations. , Consequently, the fine bubbles generated at the screen/grid mixing elements will be maintained for longer distances downstream, thereby yielding high specific interfacial areas which should enhance the value of the volumetric mass-transfer coefficient. This was experimentally confirmed by Chen and by the population balance simulation results undertaken by Azizi and Al Taweel .…”

Section: Resultsmentioning

confidence: 99%

“…18 On the other hand, bubble coalescence rate is strongly hindered by the presence of very small SDS concentrations. 49,82 Consequently, the fine bubbles generated at the screen/grid mixing elements will be maintained for longer distances downstream, thereby yielding high specific interfacial areas which should enhance the value of the volumetric mass-transfer coefficient. This was experimentally confirmed by Chen 10 and by the population balance simulation results undertaken by Azizi and Al Taweel.…”

Section: Effect Of Interfacial Characteristicsmentioning

confidence: 99%

Mass Transfer in an Energy-Efficient High-Intensity Gas–Liquid Contactor

Azizi

Al‐Taweel

2015

Ind. Eng. Chem. Res.

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To improve the selectivity and yield of multiphase reactions, an attempt to intensify gas–liquid mass-transfer operations was undertaken in which screen/grid static mixers were used to promote interphase mass transfer. A modified technique was used to enhance the reproducibility of the results and to account for the depletion effect which becomes critical at high mass-transfer rates. The volumetric mass transfer coefficient, k L a, was found to increase with increasing liquid superficial velocity and gas volume fraction and reached values as high as 4.08 s–1 at low specific energy consumption rates, particularly for slowly coalescent systems, a situation that is encountered in most industrially relevant systems. The gas–liquid reactor/contactor presently investigated takes advantage of the coalescence retardation characteristics of most industrially relevant streams to achieve k L a values that surpassed those of most conventional reactor/contactors by more than an order of magnitude while maintaining a high energy utilization efficiency (up to 0.63 kg O2/kWh). The ability to reach 98% equilibrium within residence times of less than 800 ms, achieved without significantly increasing the power consumption rates, allows for the use of static mixing reactor volumes that are several orders of magnitude smaller than conventional units such as mechanically agitated tanks and bubble columns.

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“…For sparged stirred tanks of standard geometry mainly the date of the spatial distribution of gas holdup 5 and bubble size distribution (BSD) 6 in equipment stirred has been investigated with a single impeller 7 or a dual 8,9 or triple turbine 10,11 . The principal advantage of GIMAC and SAR over SLR and JLR lies in the avoidance of compression and recovery equipment.…”

Section: Introductionmentioning

confidence: 99%

Experimental research on gas‒liquid dispersion in a stirred tank by a novel long‒short blades agitator

Wu¹,

Luo²,

Chen³

2022

Preprint

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We used vertical short blades (SBs) and two pitched SBs with the inclined angles of the SBs from 60° to 45°, and compared the gas holdup, bubble size and interfacial area measured by the electrical conductivity probe technique when the agitator was operated in the down‒pumping and up‒pumping modes. Results show that higher gas holdup with large bubble size in the upper part and lower gas holdup but with small bubble size in the lower part of the tank. The effective fluid exchange between the radial flow generated by the long blades (LBs) and the strong axial flow generated by the SBs redistribute the bubbles effectively in the whole stirred tank. The gas phase is more evenly distributed in the whole tank with higher local gas holdup when the rotating speed is high enough. In the case of up‒pumping mode, the 45U impeller can further improve the gas‒liquid interface area. The correlation of power input and rotating speed on gas holdup is fitted.

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Gas Flow Behavior in a Two‐Phase Reactor Stirred with Triple Turbines

Cited by 10 publications

References 18 publications

Gas Hold‐Up Evaluation Using the Analytical Solution of the Axial Dispersion Model: Comparison with Static Measurement Results

Gas Hold‐Up Evaluation Using the Analytical Solution of the Axial Dispersion Model: Comparison with Static Measurement Results

Mass Transfer in an Energy-Efficient High-Intensity Gas–Liquid Contactor

Experimental research on gas‒liquid dispersion in a stirred tank by a novel long‒short blades agitator

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