Determination of bubble size distributions in bubble columns using LDA

Kulkarni, Amol A.; Joshi, Jyeshtharaj B.; Ramkrishna, Doraiswami

doi:10.1002/aic.10274

Cited by 39 publications

(28 citation statements)

References 25 publications

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“…They predicted the timeaveraged Sauter mean bubble diameter at different elevations from the inlet of the SBCR, the gas holdup at different catalyst concentration, and the axial variation of the time-averaged Sauter mean bubble diameter along the reactor axis at different catalyst concentrations. Their results were then validated against the experimental data by Kulkarni et al [449] for air-water bubble columns at standard atmospheric conditions. Moreover, they also modeled the effect of the syngas inlet velocity on its conversion and reactor productivity; however, these results were not validated against any experimental data.…”

Section: Cfd Modeling Of Sbcrsmentioning

confidence: 76%

Fischer–Tropsch Synthesis in Slurry Bubble Column Reactors: Experimental Investigations and Modeling – A Review

Basha

Sehabiague

Abdel‐Wahab

et al. 2015

International Journal of Chemical Reactor Engineering

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This paper presents an extensive review of the kinetics, hydrodynamics, mass transfer, heat transfer and mathematical as well as computational fluid dynamics (CFD) modeling of Low-Temperature Tropsch Synthesis (LTFT) synthesis in Slurry Bubble Column Reactors (SBCRs), with the aim of identifying potential research and development areas in this particular field. The kinetic expressions developed for F-T synthesis over iron and cobalt catalysts along with the water gas shift (WGS) reactions are summarized and compared. The experimental data and empirical correlations to predict the hydrodynamics (gas holdup, Sauter mean bubble diameter, and bubble rise velocity), mass transfer coefficients and heat transfer coefficients are presented. The effects of various operating variables, including pressure, temperature, gas velocity, catalyst concentration, reactor geometry, and reactor internals on the hydrodynamic and transport parameters as well as the performance of SBCRs are discussed. Additionally, modeling efforts of SBCRs, using axial dispersion models (ADM), multiple cell recirculation models (MCCM) and computational fluid dynamics (CFD), are addressed. This review revealed the following:(1) Numerous F-T and WGS kinetic rate expressions are available for cobalt and iron catalysts and one must be careful in selecting the appropriate expressions for LTFT. Iron catalyst suffers from severe attrition and subsequent deactivation in SBCRs and accordingly building a costly catalyst manufacturing facility onsite is required to maintain a steady operation of the F-T reactor;(2) Experimental data on the hydrodynamic and transport parameters at high pressures and temperatures, typical to those of actual F-T synthesis, remain scanty when compared with the plethora of studies conducted using air-water systems in small reactors at ambient conditions; (3) Several empirical correlations for predicting the hydrodynamic and mass as well heat transfer parameters are available and one should select those which consider the reactor diameter, gas mixtures and the potential foamability of the F-T liquids; (4) The effect of cooling internals configuration and sparger design on the hydrodynamic and transport parameters, local turbulence, mixing and catalyst attrition are yet to be seriously addressed; (5) The impact of operating variables on the hydrodynamic and transport parameters as well as the overall performance of the SBCRs should be investigated using actual F-T fluid-solid systems under typical pressures and temperatures using a large-scale reactor ( > 0.15 m ID) in the presence of gas spargers and cooling internals; (6) Significant efforts are still required in order to advance CFD modeling of SBCRs, particularly those pertaining to the relevant closure models, such as drag, lift and turbulence. Also, cooling internals configuration and the design as well as orientation of gas spargers should be accounted for in the CFD modeling; and (7) Proper validations of the CFD formulations using actual systems for F-T SBCR are needed.

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Section: Cfd Modeling Of Sbcrsmentioning

confidence: 76%

Fischer–Tropsch Synthesis in Slurry Bubble Column Reactors: Experimental Investigations and Modeling – A Review

Basha

Sehabiague

Abdel‐Wahab

et al. 2015

International Journal of Chemical Reactor Engineering

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“…Comparison of predicted bubble size distribution by using the cell average method and the fixed pivot method with the reported experimental data at different locations at V g = 0.02 m s −1 .…”

Section: Resultsmentioning

confidence: 99%

“…Comparison of simulated radial profiles of axial liquid velocity by the fixed pivot method and the cell average method with the reported experimental data[36] at different axial positions (h/D) at V g = 0.02 m s -1 . Predicted distributions of the Sauter mean diameter (V g = 0.02 m s -1 ).…”

mentioning

confidence: 99%

Simulation of a Bubble Column by Computational Fluid Dynamics and Population Balance Equation Using the Cell Average Method

Cheng

Yang

et al. 2017

Chem Eng & Technol

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An axisymmetric computational fluid dynamics (CFD) simulation coupled with a population balance equation (PBE) has been applied in simulating the gas‐liquid flow in a bubble column with an in‐house code. The novel feature of this simulation is the application of the cell average method in a CFD‐PBE coupled model for the first time. The predicted results by this method are compared with those by the traditional fixed pivot method and experimental data. For both methods, the simulated results are in reasonable agreement with the reported experimentally measured values. However, the bubble size distributions determined by the cell average method are slightly better than those found by means of the fixed pivot method, i.e., the latter provides a smaller peak value and a wider bubble size distribution, and the probability density function of large bubbles is higher.

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“…There are various approaches to determine a bubble size distribution. The most commonly used approaches are based on photographic [4,5,11,12], electroresistivity [13], optic [2,9,[14][15][16], and acoustic techniques [17][18][19][20][21][22][23][24]. However, such approaches have limited applicability due to changes in rates of bubble collapse and bubble concentrations with respect to time.…”

Section: Introductionmentioning

confidence: 99%

Determination of bubble size distribution in gas–liquid two‐phase systems via an ultrasound‐based method

Chen

Hussein

Becker

2017

Engineering in Life Sciences

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Over the past few years, ultrasonic techniques are increasingly used to determine bubble size distribution in gas-liquid two-phase systems. However, the development of a precise and efficient measuring system is very challenging because bubbles are dynamic and unstable relative to time and space in a moving fluid, thus hindering an accurate validation of the measuring system. Therefore, this study examined the possibility of using artificial bubbles to establish an ultrasonic measuring system. The main concept for this study involved developing an ultrasound-based measuring system with the aid of a certain type of artificial bubbles. The developed system was subsequently adapted to the bypass pipeline of a propagator to demonstrate the reliability of this concept. The results indicated that the established system could measure a microbubble size distribution with a root mean squared error of validation that corresponded to 0.1243 % v/v. Additionally, the estimates of real bubble measurement agreed well with the reference method. Thus, this study demonstrated that the developed system could be a potential method to determine bubble size distributions in gas-liquid two-phase systems.

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Determination of bubble size distributions in bubble columns using LDA

Abstract: A new method is developed for the determination of bubble size distributions from experimental laser Doppler anemometry (LDA) data through simultaneous measurement of only two orthogonal velocity components and the intermittent time gaps arising out of

Cited by 39 publications

References 25 publications

Fischer–Tropsch Synthesis in Slurry Bubble Column Reactors: Experimental Investigations and Modeling – A Review

Fischer–Tropsch Synthesis in Slurry Bubble Column Reactors: Experimental Investigations and Modeling – A Review

Simulation of a Bubble Column by Computational Fluid Dynamics and Population Balance Equation Using the Cell Average Method

Determination of bubble size distribution in gas–liquid two‐phase systems via an ultrasound‐based method

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