Mass transfer and hydrodynamic characteristics of a high aspect ratio self-ingesting reactor for gas–liquid operations

Scargiali, Francesca; Russo, Roberto; Grisafi, F.; Brucato, Alberto

doi:10.1016/j.ces.2006.11.040

Cited by 34 publications

(8 citation statements)

References 30 publications

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“…As N becomes greater than N C , the gas phase gets entrained into the liquid, leading to formation of bubbles and cavities behind the impellers, reducing the apparent density and viscosity of the liquid phase. Consequently, as typically found in the literature, N P decreases. Thus, a plot of N p vs. N can indicate how the operating parameters and the configurations of the agitator affect the entrainment of the gas phase.…”

Section: Resultssupporting

confidence: 75%

Gas‐liquid mass transfer behavior in a surface‐aerated vessel stirred by a novel long‐short blades agitator

Luo

Pan

et al. 2015

AIChE Journal

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in Wiley Online Library (wileyonlinelibrary.com)For a recently developed long-short blades (LSB) agitator, its critical rotational speed for the onset of gas entrainment, power number, and gas-liquid mass transfer behavior in the case of surface aeration is investigated. The effect of the LSB configurations and the liquid level on the agitator performance has been studied in details. The obtained results clearly show several advantages of the LSB agitator in gas-liquid mass transfer with respect to the agitators in the literature. It is found that its gas-liquid volumetric mass-transfer coefficient at a given specific power can be several times larger than those shown in the literature. It can also avoid decrease in the gas-liquid mass transfer rate as the liquid level increases. In addition, the bubble distribution in the system is more uniform with respect to conventional agitators, resulting from better distribution of the dissipated energy for the LSB agitator. Figure 2. Schematic diagram of the reactor configuration.(a) reactor; (b) LSB agitator with long blades fixed on the outer ring and (c) on the inner ring. (1) Fixer; (2) Long blades; (3) Outer and inner connector rings; (4) Short blades.

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Section: Resultssupporting

confidence: 75%

Gas‐liquid mass transfer behavior in a surface‐aerated vessel stirred by a novel long‐short blades agitator

Luo

Pan

et al. 2015

AIChE Journal

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“…During pure oxygen absorption, there is no problem with driving force description in the model, thus the resulting k L a should be physically correct. On the contrary, the modeling of air absorption is more complicated and neglecting the nitrogen transport can cause significant underestimation of k L a data especially in non-coalescent batch at high gas flow rates [21,22,25,26,30].…”

Section: Mass Transfer-comparison Of Pure Oxygen and Air Absorptionmentioning

confidence: 99%

“…Data differences can be attributed to the different hydrodynamic conditions in the bubble column generated by different types of gas distributors and also to the various methods used for k L a measurements. As different measurement methods can be affected by different assumptions and simplifications, various errors in k L a results can occur [8,[19][20][21]. In all the articles presented in Table 1, dynamic methods were used where physical absorption (without chemical reaction) of oxygen into a liquid occurs and the change of oxygen concentration is recorded by a probe and fitted by a theoretical model with k L a as the optimized parameter.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Volumetric Mass Transfer Coefficient in Bubble Columns

et al. 2018

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Abstract:The paper presents a brief overview of experiments on volumetric mass transfer coefficient in bubble columns. The available experimental data published are often incomparable due to the different type of gas distributor and different operating conditions used by various authors. Moreover, the value of the coefficient obtained experimentally is very sensitive to the particular method and to the physical models used in its evaluation. It follows that the Dynamic Pressure Method (DPM) is able to provide physically correct values not only in lab-scale contactors but also in pilot-scale reactors. However, the method was not correctly proven in bubble columns. In present experiments, DPM was employed in a laboratory-scale bubble column with a coalescent phase and tested in the pure heterogeneous flow regime. The method was successfully validated by the measurements under two different conditions relevant to the mass transfer. First, the ideal pressure step was compared with the non-ideal pressure step. Second, the pure oxygen absorption was compared with the simultaneous oxygen-and-nitrogen absorption. The obtained results proved that DPM is suitable for measuring the mass transport in bubble columns and to provide reliable data of volumetric mass transfer coefficient.

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“…Joshi and Sharma (1977); Sawant and Joshi (1979); Joshi (1980); Sawant et al (1981); Rielly et al (1992); Forrester and Rielly (1994); Forrester et al (1998); Poncin et al (2002); Murthy et al (2007a); Scargiali et al (2007b); Murthy et al (2008a)…”

Section: Introductionmentioning

confidence: 99%

CFD simulation of stirred tanks: Comparison of turbulence models. Part I: Radial flow impellers

et al. 2011

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A critical review of the published literature regarding the computational fluid dynamics (CFD) modelling of single-phase turbulent flow in stirred tank reactors is presented. In this part of review, CFD simulations of radial flow impellers (mainly disc turbine (DT)) in a fully baffled vessel operating in a turbulent regime have been presented. Simulated results obtained with different impeller modelling approaches (impeller boundary condition, multiple reference frame, computational snap shot and the sliding mesh approaches) and different turbulence models (standard k − ε model, RNG k − ε model, the Reynolds stress model (RSM) and large eddy simulation) have been compared with the in-house laser Doppler anemometry (LDA) experimental data. In addition, recently proposed modifications to the standard k − ε models were also evaluated. The model predictions (of all the mean velocities, turbulent kinetic energy and its dissipation rate) have been compared with the experimental measurements at various locations in the tank. A discussion is presented to highlight strengths and weaknesses of currently used CFD models. A preliminary analysis of sensitivity of modelling assumptions in the k − ε models and RSM has been carried out using LES database. The quantitative comparison of exact and modelled turbulence production, transport and dissipation terms has highlighted the reasons behind the partial success of various modifications of standard k − ε model as well as RSM. The volume integral of predicted energy dissipation rate is compared with the energy input rate. Based on these results, suggestions have been made for the future work in this area.Nous présentons un examen critique de la littérature concernant la modélisation de la dynamique des fluides numérique (DFN) de l'écoulement turbulentà une phase dans les réacteursà cuve agitée. Dans cette partie de l'examen, nous présentons les simulations de DFN de turbinesà ecoulement radial (principalement des turbinesà disque (TD)) dans un réservoir entièrement cloisonné effectuées dans un régime turbulent. Les résultats des simulations obtenus grâceà différentes approches de modélisation des turbines (couche limite turbulente, méthode des référentiels multiples, snap-shot de modélisation numérique, maillage glissant) età différents modèles de turbulence (modèle standard k-e, modèle RNG k-e, modèle aux tensions de Reynolds et simulation des grandeséchelles) ontété comparés aux données expérimentales internes d'allocation de Dirichlet latente (ADL). De plus, les modifications des modèles standards k-e récemment proposées ontégalementétéévaluées. Les prédictions du modèle (de toutes les vitesses moyennes, de l'énergie cinétique turbulente et de son taux de dissipation) ontété comparées aux données expérimentales relevéesà différents endroits de la cuve. Une discussion présente les points forts et les points faibles des modèles de DFN actuellement utilisés. Une analyse préliminaire de la sensibilité des hypothèses de modélisation liées aux modèles k-e et RSM aété menée en utilis...

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Mass transfer and hydrodynamic characteristics of a high aspect ratio self-ingesting reactor for gas–liquid operations

Cited by 34 publications

References 30 publications

Gas‐liquid mass transfer behavior in a surface‐aerated vessel stirred by a novel long‐short blades agitator

Gas‐liquid mass transfer behavior in a surface‐aerated vessel stirred by a novel long‐short blades agitator

Measurement of Volumetric Mass Transfer Coefficient in Bubble Columns

CFD simulation of stirred tanks: Comparison of turbulence models. Part I: Radial flow impellers

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