21 results on '"Multiphase reactors"'
Search Results
2. Antibubble column: A mean to measure and enhance liquid–gas mass transfer through surfactant-laden interfaces.
- Author
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Miguet, Jonas, Dorbolo, Stéphane, and Scheid, Benoit
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MASS transfer coefficients , *MASS transfer , *IMMERSION in liquids , *SURFACE active agents , *MONOMOLECULAR films - Abstract
Antibubbles are ephemeral objects composed of a liquid core encapsulated by a thin gas shell immersed in a liquid bulk. The gas shell thickness evolves in time, driven by two contributions: gravitational drainage and gas–liquid mass transfer. The low density contrast between the antibubble and the bulk, as well as its weak deformability constitute advantages that are used to measure the mass transfer coefficient (MTC) in a so-called antibubble column, in a time-resolved fashion. Shells made with pure air give low data reproducibility. Consequently, perfluorohexane, a low-solubility gas, was mixed to air to enforce gas desorption from the bulk and obtain reliable data. MTC obtained with various surfactants and concentrations are found to deviate from the Frössling correlation built for fully rigid interfaces: higher MTC are consistent with partially rigid interfaces due to a partial coverage of surfactants along a so-called spherical cap, while lower MTC are consistent with an additional resistance to the transfer of mass due to the presence of surfactants forming a monolayer at high concentration. Finally, the advantages in terms of control and compactness of an antibubble column as compared to a bubble column for liquid–gas mass transfer are demonstrated. Specifically, an antibubble is shown to transfer dozens of times more mass than a bubble that would initially carry the same amount of gas. Antibubbles are therefore shown to provide a new, time-resolved, way to measure MTC, as well as promising route to enhance liquid–gas transfers in multiphase reactors. • Time-resolved mass transfer coefficient measurement using antibubble. • Results and discussion for different types and concentrations of surfactants. • An antibubble is shown to exchange 30x more mass than a bubble of equivalent radius. • Technical description and theoretical predictions for the mass transfers are provided. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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3. Particle dynamics in horizontal stirred bed reactors characterized by single-photon emission radioactive particle tracking.
- Author
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van der Sande, P. Christian, Wagner, Evert C., de Mooij, Jack, Meesters, Gabrie M.H., and van Ommen, J. Ruud
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PARTICLE emissions , *GRANULAR flow , *RADIAL flow , *POLYPROPYLENE manufacturing , *ROTATIONAL motion , *PARTICLE dynamics , *PARTICLE analysis - Abstract
Horizontal stirred bed reactors are widely used in the commercial manufacturing of polypropylene. However, a comprehensive understanding of the particle dynamics in horizontal stirred bed reactors remains elusive, primarily due to the lack of detailed experimental data. In this work, we studied the influence of operating parameters on the particle flow dynamics in a laboratory-scale horizontal stirred bed reactor using single-photon emission radioactive particle tracking. The results show that the general solids flow behavior is strongly affected by both the agitator rotation speed and reactor fill level. Operation at low rotation speed and low fill level results in solids flow with poor radial and circumferential distribution due to internal bed circulation. On the contrary, at increased rotation speeds and fill levels, solids motion throughout the bed is continuous resulting in excellent solids distribution. The solids circulation was found to increase for both an increase in rotation speed and reactor fill level. The axial dispersion coefficient, on the other hand, shows a linear relation with the rotation speed, but no conclusive relation between the axial dispersion coefficient and the reactor fill level was found. • A horizontal stirred bed reactor is studied using radioactive particle tracking. • The flow pattern, solid circulation, and axial dispersion are analyzed. • Fill level and rotation speed have a significant influence on the particle dynamics. [ABSTRACT FROM AUTHOR] more...
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- 2024
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4. O2 mass transfer in an oscillatory flow reactor provided with smooth periodic constrictions. Individual characterization of [formula omitted] and [formula omitted].
- Author
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Ferreira, A., Teixeira, J.A., and Rocha, F.
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MASS transfer , *OXYGEN analysis , *OSCILLATING chemical reactions , *CHEMICAL reactors , *SIZE reduction of materials - Abstract
In the present work the superficial gas velocities ( u G ) and the oscillatory conditions (frequency and amplitude) effects on the gas–liquid mass transfer process in a novel oscillatory flow reactor provided with smooth periodic constrictions (OFR-SPC) are experimentally evaluated. The liquid-side mass transfer coefficient, k L , and the specific interfacial area, a , are studied individually. The specific interfacial area is obtained using the new automatic image analysis technique developed by Ferreira et al. (2012). The experimental results of volumetric liquid side mass transfer coefficient ( k L a ), Sauter mean diameter ( d 32 ) and gas holdup ( ε G ), and the calculated values of a and k L , are correlated with the superficial gas velocity and the power density ( P / V ), in order to be used in scale-up processes and in comparisons with the literature. The results show that k L a increases with both superficial gas velocity and oscillatory conditions, the last ones having the highest impact on the mass transfer process. The increase in the oscillation motion (frequency and amplitude) results in bubble size reduction (from ∼7 mm, without oscillation, to ∼1 mm, with oscillation), in bubble average residence time increase and, consequently, in a increase. A k L increase with d 32 decrease is observed, showing the importance of hydrodynamic phenomena on k L , specially, when very low bubbles sizes are presented in oscillatory flow reactors. [ABSTRACT FROM AUTHOR] more...
- Published
- 2015
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5. Discrete element study of solid circulating and resident behaviors in an internally circulating fluidized bed.
- Author
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Yang, Shiliang, Luo, Kun, Fang, Mingming, Fan, Jianren, and Cen, Kefa
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DISCRETE element method , *CIRCULATING fluidized bed combustion , *DISTRIBUTION (Probability theory) , *FLUIDIZATION , *SOLID-phase analysis - Abstract
Highlights: [•] Solid circulation is constructed in the ICFB with the formations of three local rolls. [•] Solid cycle time shows a log-normal probability distribution pattern. [•] Enlarging the fluidizing velocity in the RC or HEC reduces the solid cycle time. [•] Large residence time of solid phase appears in the two corners of the bed. [•] Increasing the baffle incline angle or gap height reduces solid residence time in HEC. [ABSTRACT FROM AUTHOR] more...
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- 2014
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6. Mass transfer coefficients of styrene into water/silicone oil mixtures: New interpretation using the “equivalent absorption capacity” concept.
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Dumont, Eric, Andrès, Yves, and Cloirec, Pierre Le
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MASS transfer coefficients , *SILICONES , *ABSORPTION , *STYRENE , *AIR-water interfaces , *MIXTURES - Abstract
Highlights: [•] Styrene absorption into water/silicone oil mixtures was investigated. [•] Mixtures were considered pseudo-homogeneous phases. [•] Oil addition hindered the mass transfer rate compared to the air/water system. [•] An apparent decrease in KLa values due to silicone oil addition was observed. [•] It is questionable to study the change in KLa in terms of silicone oil addition. [ABSTRACT FROM AUTHOR] more...
- Published
- 2014
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7. The influence of surface properties on chemical reaction in multiphase flow in capillaries.
- Author
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Hecht, Kristin, Fröhlich, Georg, Pfeifer, Peter, Dittmeyer, Roland, and Kraushaar-Czarnetzki, Bettina
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SURFACE chemistry , *CHEMICAL reactions , *MULTIPHASE flow , *WETTING , *GAS-liquid interfaces , *MICROFLUIDIC devices , *CHEMICAL reactors , *CARBON dioxide adsorption - Abstract
This contribution discusses the influence of material wettability on gas/liquid flow and reaction in capillaries. It is shown that the performance of microfluidic devices as chemical reactors can be enhanced by choosing wall materials promoting wettability. Previous investigations have revealed differences in gas/liquid flow patterns depending on material wettability. In this work, high speed video observations of flow have been combined with experiments using the absorption of CO2 into aqueous solutions of sodium hydroxide. A pseudo-1st-order reaction assumption has been used to determine values of interfacial area in 250μm capillaries of fused silica (contact angle θ ≈50°), PEEK (θ ≈65°), and FEP (θ ≈95°). Increases in chemical conversion occurring with more wettable materials are attributed to increases in the interfacial area. The interfacial areas correlate with the flow patterns observed. Characterization of important parameters such as interfacial area and mass transport are lacking for microchannel and capillary flows. Chemical reaction can be used to examine these parameters to better understand gas/liquid flow. [ABSTRACT FROM AUTHOR] more...
- Published
- 2013
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8. Hydrodynamics and gas–liquid mass transfer in a horizontal rotating foam stirrer reactor
- Author
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Leon, M.A., Maas, R.J., Bieberle, A., Schubert, M., Nijhuis, T.A., van der Schaaf, J., Hampel, U., and Schouten, J.C.
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HYDRODYNAMICS , *GAS-liquid interfaces , *MASS transfer , *MIXING machinery , *CHEMICAL reactors , *MULTIPHASE flow , *POROSITY - Abstract
Abstract: This paper describes a new multiphase reactor, the horizontal rotating foam stirrer reactor, which uses a donut-shaped foam block mounted on a horizontal shaft functioning as a stirrer and as a catalyst support. The effect of different operational conditions such as stirring speed, reactor length, foam porosity, foam thickness and the presence of baffles on the gas–liquid mass transfer and the gas–liquid flow distribution is discussed for the systems water/air and glycerol/air. The rate of gas–liquid mass transfer is measured spectrometrically while the hydrodynamics of the reactor is studied by γ-ray tomography. For a partially filled reactor, three flow states could be distinguished: the trickle state, the slosh state and the ring state. In the trickle state the liquid flows in a thin stream over the foam while in the slosh state the liquid is pushed upward by the stirrer and sprayed, leading to the formation of fine liquid droplets and fine gas bubbles. The transition between the trickle state and the slosh state occurs at 200rpm. This is drastically affected by the liquid viscosity and in some extent by the reactor length and the foam thickness. When the stirring speed is constant, the ring state, which results in a cylindrical liquid layer on the inside wall, appears with increasing the liquid content in the reactor (above 70%). Due to a large gas–liquid interface in the slosh state, a high gas–liquid mass transfer is achieved. k GL a GL values up to 0.32s−1 are found. This is comparable to gas–liquid mass transfer rates in slurry reactors. However, in case of the foam stirrer a higher power input per liquid volume is needed in order to achieve the minimum stirrer speed required for complete dispersion of the gas. It is shown that mass transfer coefficients decreased with increasing viscosity, while the centrifugal force revealed to be effective in enhancing mass transfer in a viscous media. Conclusions on the optimal reactor configuration are drawn for the application in the fine chemical industry. [Copyright &y& Elsevier] more...
- Published
- 2013
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9. Statistical tool combined with image analysis to characterize hydrodynamics and mass transfer in a bubble column
- Author
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Ferreira, A., Pereira, G., Teixeira, J.A., and Rocha, F.
- Subjects
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IMAGE analysis , *HYDRODYNAMICS , *MASS transfer , *PARTICLE size distribution , *BUBBLES , *FACTOR analysis , *TEMPERATURE effect , *SURFACE tension - Abstract
Abstract: Image analysis technique has been proved to be very effective in the quantification of particles size and morphology distributions in different work areas. In the present work this technique was combined with the discriminant factorial analysis (DFA) in order to allow the automatic identification of single bubbles (isolated bubbles without influence of surrounded bubbles) in multiphase systems. With the previous methodology it has been possible to distinguish online and automatically among three different classes of bubbles (single bubbles and medium complexity and large complexity bubbles groups), allowing for the first time the computation of the local bubble population complexity in the system. The automatic and correct characterization of the single bubbles allowed the correct determination of bubble size and, consequently, the specific interfacial area a at different experimental conditions. Agreement between automated and manual classification, measured in terms of a performance index, is 98% for single bubbles identification. Further, the present work describes the application of such methodology to the study of temperature, type of gas sparger, and liquid phase properties (viscosity and surface tension) influence on the individual components of volumetric liquid side mass transfer coefficient, k L a. The results show that the different experimental parameters and liquid properties act by a particular way on k L and a. [Copyright &y& Elsevier] more...
- Published
- 2012
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10. Comparison of structured trickle-bed and monolithic reactors in Pd-catalyzed hydrogenation of alpha-methylstyrene
- Author
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Bauer, Tobias and Haase, Stefan
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MONOLITHIC reactors , *PALLADIUM catalysts , *HYDROGENATION , *STYRENE , *HYDRODYNAMICS , *DROPLETS - Abstract
Abstract: The so-called structured trickle-bed reactors (STBRs) represented by the combination of a tubular reactor and a structure with straight flow channels packed with catalyst particles have been tested for carrying out multiphase reactions. The highly efficient reactor performance of these reactors is observed in hydrogenation of alpha-methylstyrene by virtue of intensive gas–liquid–solid mass transfer even at moderate gas and liquid velocities. Different variants of STBR have been proven and compared with each other as well as with the conventional reactors. The comparison shows that STBR, especially monoliths packed with particles, demonstrate the highest space-time yield, but at the expense of an elevated pressure drop. [Copyright &y& Elsevier] more...
- Published
- 2011
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11. Temperature and solid properties effects on gas–liquid mass transfer
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Ferreira, A., Ferreira, C., Teixeira, J.A., and Rocha, F.
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MASS transfer , *TEMPERATURE effect , *CHEMICAL reactors , *ABSORPTION , *PARTICLES , *BUBBLE dynamics , *HYDRODYNAMICS - Abstract
Abstract: The knowledge about the effect of solid phase properties, at different temperatures, on gas–liquid transfer and the respective physical mechanisms has been poorly studied. In the present work, the temperature and solid properties (size and density) effects on the gas–liquid mass transfer characteristics in a bubble column were experimentally evaluated. Gas–liquid–solid systems formed by air/water/polyvinyl chloride (PVC) beads and air/water/expandable polystyrene (EPS) beads were used. For each system, volumetric liquid side mass transfer coefficient, k L a, was determined under different temperatures (20–35°C), superficial gas velocities (up to 7.2mm/s), solids sizes (210, 549 and 591μm) and concentration (up to 5vol.%). The results show that the temperature plays an important role on mass transfer phenomena as k L a increases as temperature is increased. However, temperature does not have, significantly, influence on the solids effect on k L a. In what concerns the effect of the solids on k L a, a negative effect of their presence is observed being this effect more pronounced for the largest particles (for PVC). In addition, for the same solid size, a decrease in k L a occurs when the solid loading increases (observed in both cases, PVC and EPS). Complementary, bubble/particle interaction studies, using an image analysis technique, were also done aiming a better understanding of the effects of the two types of particles – PVC and EPS – on k L a values, being clearly confirmed that physical (e.g. density) and chemical properties of the solids are important parameters to be taken into account on mass transfer and hydrodynamic studies. Based on theoretical models for k L and a, an empirical correlation for k L a dependence on the experimental variables was developed. The experimental results were fitted with a mean deviation of 5%, that is similar to the experimental error (5%). [Copyright &y& Elsevier] more...
- Published
- 2010
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12. CFD study of an evaporative trickle bed reactor: Mal-distribution and thermal runaway induced by feed disturbances
- Author
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Strasser, Wayne
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COMPUTATIONAL fluid dynamics , *EVAPORATION (Chemistry) , *CHEMICAL reactors , *NUMERICAL analysis , *PHASE transitions , *HIGH pressure chemistry , *MULTIPHASE flow , *POROUS materials , *HEAT transfer - Abstract
Abstract: A numerical study was carried out to investigate steady-state and transient phase distribution, evaporation, and thermal runaway in a large-scale high-pressure trickle bed reactor. A cooling recycle stream, containing reaction products and a fresh feed, was included via a closed loop calculation. It was found that, as expected, phase distribution in the catalyst bed had a substantial impact on production rate; a faulty feed distribution system can cost approximately 20% in overall steady-state product conversion. In the event that the cooling recycle stream is lost, the external reactor shell temperature can exceed its design intent. It was found that reducing the quantity of fresh reactant feed in this situation can dramatically reduce the potential for vessel damage. Thermal inertia of the catalyst particles proved to be a significant contribution to the transient energy balance. Model results are supported with a posteriori thermal excursion plant data. [Copyright &y& Elsevier] more...
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- 2010
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13. Model based control of a liquid swelling constrained batch reactor subject to recipe uncertainties
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Simon, Levente L., Nagy, Zoltan K., and Hungerbuhler, Konrad
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CHEMICAL reactors , *BATCH processing , *MULTIPHASE flow , *PREDICTIVE control systems , *NONLINEAR statistical models , *ALGORITHMS , *SIMULATION methods & models - Abstract
Abstract: This work presents the application of nonlinear model predictive control (NMPC) to a simulated industrial batch reactor subject to safety constraint due to reactor level swelling, which can occur with relatively fast dynamics. Uncertainties in the implementation of recipes in batch process operation are of significant industrial relevance. The paper describes a novel control-relevant formulation of the excessive liquid rise problem for a two-phase batch reactor subject to recipe uncertainties. The control simulations are carried out using a dedicated NMPC and optimization software toolbox OptCon which implements efficient numerical algorithms. The open-loop optimal control problem is computed using the multiple-shooting technique and the arising nonlinear programming problem is solved using a sequential quadratic programming (SQP) algorithm tailored for large-scale problems, based on the freeware optimization environment HQP. The fast response of the NMPC controller is guaranteed by the initial value embedding and real-time iteration technologies. It is concluded that the OptCon implementation allows small sampling times and the controller is able to maintain safe and optimal operation conditions, with good control performance despite significant uncertainties in the implementation of the batch recipe. [Copyright &y& Elsevier] more...
- Published
- 2009
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14. Multifractal detrended fluctuation analysis of combustion flames in four-burner impinging entrained-flow gasifier
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Niu, Miao-Ren, Zhou, Wei-Xing, Yan, Zhuo-Yong, Guo, Qing-Hua, Liang, Qin-Feng, Wang, Fu-Chen, and Yu, Zun-Hong
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MULTIFRACTALS , *COMBUSTION reactors , *FLAME visualization , *CCD cameras , *FLUCTUATIONS (Physics) , *ANALYTICAL chemistry - Abstract
Abstract: On a laboratory-scale testing platform of an impinging entrained-flow gasifier with four opposed burners, the flame images for diesel combustion and gasification process were recorded with a single charge coupled device (CCD) camera. The two-dimensional multifractal detrended fluctuation analysis was employed to investigate the multifractal nature of the flame images. Sound power-law scaling relations in the annealed average of detrended fluctuations were unveiled when the order , and the multifractal feature of flame images was confirmed. Further analyses identified two multifractal parameters, the minimum and maximum singularities and , serving as characteristic parameters of the multifractal flames. These two characteristic multifractal parameters vary with respect to different experimental conditions. [Copyright &y& Elsevier] more...
- Published
- 2008
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15. Liquid mixing and gas–liquid mass transfer in a three-phase inverse turbulent bed reactor
- Author
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Sánchez, Omar, Michaud, Sébastien, Escudié, Renaud, Delgenès, Jean-Philippe, and Bernet, Nicolas
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FLUID dynamics , *THERMODYNAMICS , *HYDRODYNAMICS , *POTASSIUM chloride - Abstract
Abstract: In this research work, hydrodynamic characteristics and gas–liquid mass transfer in a laboratory scale inverse turbulent bed reactor were studied. In order to characterize internal flow in the reactor, the residence time distribution (RTD) was obtained by the stimulus-response technique using potassium chloride as a tracer. Different solid hold-up (0–0.37) and air superficial velocity (2.7–6.5mms−1) values were assayed in RTD experiments. The parameters that characterize the RTD curve, mean residence time and variance were independent of the solid hold-up, thus the solid particle concentration did not influence liquid mixing in the reactor. The hydrodynamic of the inverse turbulent bed was well represented by a model that considers the reactor as two-mixed tank of different volumes in series. The value of the volumetric gas–liquid mass transfer coefficient (k L a) was independent of the solid hold-up. This result enhances a previously suggested hypothesis, which considers that the solid and liquid form a pseudo-fluid in the inverse turbulent bed reactor. [Copyright &y& Elsevier] more...
- Published
- 2005
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16. Vortex centrifugal bubbling reactor
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Kuzmin, A.O., Pravdina, M.Kh., Yavorsky, A.I., Yavorsky, N.I., and Parmon, V.N.
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VORTEX motion , *CENTRIFUGAL force , *ROTATIONAL motion , *AERODYNAMICS - Abstract
Abstract: The vortex centrifugal bubbling apparatus is considered as a basis for a new type of multiphase vortex centrifugal bubbling reactor. In this device, a highly dispersed gas–liquid mixture is produced in the field of centrifugal forces inside the vortex chamber. The operation of the vortex centrifugal bubbling apparatus is based on the rotation of liquid by the tangential entry of gas flows via the many tangential guiding vanes around the periphery of the vortex chamber. At certain regimes there appears a highly dispersed gas–liquid vortex bubbling layer. Vortex bubbling layer represents the following unique characteristics: low hydrodynamic resistance (1000–2000Pa); homogeneity and stability over wide range of centrifugal acceleration (102 to 103 m/s2); large specific surface with the high renovation rate (of about 5m2 per 1l of water); high gas content (of about 0.5–0.6); high gas throughput (up to 200–300m3 of gas per 1l of liquid per hour) and, consequently, very high rates of heat and mass transfer. The energy consumption for the vortex bubbling layer maintenance is about 50–80W per 1l of treated liquid. The design features of the vortex chamber are described in view of the methods of stabilization of the vortex bubbling layer. The data on the hydrodynamic resistance, the structure and the lifetime of the vortex gas–liquid layer are presented. The main advantages and features of the devices of this type are discussed in view of their possible application. [Copyright &y& Elsevier] more...
- Published
- 2005
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17. Characterization of liquid phase mixing in turbulent bed contactor through RTD studies
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Bruce, A.E.R., Sai, P.S.T., and Krishnaiah, K.
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TURBULENCE , *FLUIDS , *FLUID dynamics , *DIFFUSION in hydrology - Abstract
Liquid phase mixing in a turbulent bed contactor (TBC) is experimentally characterized through residence time distribution (RTD) studies. A novel technique is employed to obtain the true exit tracer concentration and to increase the average residence time of the liquid. In this technique, an ideal mixed flow tank (MFT) is included in series with TBC. The RTD of the ideal MFT is deconvoluted from the RTD of the entire system to obtain the RTD of TBC alone. Using this method, the effect of gas and liquid velocities, static bed height, particle size and density, and number of stages on mixing of the liquid phase is studied. The experimental RTD curves are satisfactorily compared with axial dispersion model. Correlations are developed for predicting the Peclet number and the axial dispersion coefficient. It is observed in the present study that conditions close to plug flow of liquid phase can be achieved in multistage TBC. [Copyright &y& Elsevier] more...
- Published
- 2004
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18. Elevation of performance of gas–liquid reactors on solid catalyst
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Stefoglo, E.F., Drobyshevich, V.I., Semikolenov, V.A., Kuchin, I.V., and Zhukova, O.P.
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GAS chromatography , *MATHEMATICAL models - Abstract
Different kinds of initial conditions for the gas–liquid process on a solid catalyst are discussed in the paper. The advantages of process with preliminary saturation of liquid with gas are considered. For the liquid batch reactor it is theoretically shown that preliminary saturation of the initial solution with gas prior to reaction profits more in comparison with “usual” mode. The experiments on hydrogenation of ethyl ether of p-nitrobenzoic acid to anesthesyne on suspended 5% Pd/C catalyst in a batch reactor were carried out for verification of the main results from the proposed model (
PH2=40 bar,T=20–120 °C). As an example of a reactor, where the preliminary saturation effect can be used, the trickle-bed reactor operating without pumping was considered. Mathematical simulation of such type reactor is presented. [Copyright &y& Elsevier] more...- Published
- 2003
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19. A review of microwave-assisted process intensified multiphase reactors.
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Goyal, Himanshu, Chen, Tai-Ying, Chen, Weiqi, and Vlachos, Dionisios G.
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MICROWAVE heating , *MONOLITHIC reactors , *CHEMICAL reactors , *MULTISCALE modeling , *CHEMICAL processes , *CAVITY resonators - Abstract
• Overview of microwave heating of fluid–fluid and fluid–solid multiphase reactors. • Comprehensive analysis of microwave assisted process intensification. • Review of multiscale modeling and simulation of microwave multiphase reactors. • Discussion on thermal and microwave-specific effects. • Challenges and future research directions of microwave multiphase reactors. Microwaves provide alternative heating and allow process intensification due to their rapid, volumetric, and selective nature. Recognizing the central role of multiphase reactors in chemical industry, a recent surge in employing microwaves is observed. Here, we review the recent experimental and modeling investigations of microwave heating of multiphase reactors with emphasis on chemical engineering applications. We demonstrate that there is accumulated evidence for improved performance via microwave heating and a clear opportunity for further process intensification. In most of the cases, this improved performance stems from a temperature gradient between two phases. We discuss the ongoing debate on the mechanism by which microwaves affect chemical processes exacerbated by the inability of measuring the temperature distribution in a microwave cavity. We outline recent progress in this direction in monolith reactors and needs for future work. We underscore the lack of detailed modeling and simulation tools even for single-phase systems and emphasize the imperative for multiscale predictive modeling to bridge the experimental-modeling gap. Promising results are shown by a few recently published modeling studies that can predict the experimental measurements in complex multiphase reactors. A combination of experimental and modeling tools can provide a comprehensive picture of the microwave multiphase reactors as well as a means toward scale-up and optimization. [ABSTRACT FROM AUTHOR] more...
- Published
- 2022
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20. Process intensification of a photochemical oxidation reaction using a Rotor-Stator Spinning Disk Reactor: A strategy for scale up.
- Author
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Chaudhuri, Arnab, Kuijpers, Koen P.L., Hendrix, Raoul B.J., Shivaprasad, Parimala, Hacking, Jasper A., Emanuelsson, Emma A.C., Noël, Timothy, and van der Schaaf, John
- Subjects
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ROTATING disks , *TECHNOLOGICAL progress , *VISIBLE spectra , *MASS transfer , *LIGHT sources , *DYE-sensitized solar cells - Abstract
• The RS-SDR allows to scale gas–liquid photochemical oxidations. • An increase in mass transfer improves the selectivity of gas–liquid photochemistry. • Reduced reaction times are seen due to homogeneous irradiation and intensified mass transport. • The RS-SDR displays a low pressure drop, even at high flow rates. Photochemical transformations have witnessed a remarkable growth of attention in the past decade due to the popularity of photoredox catalysis and the technological progress in energy-efficient light sources. However, the scaling of these photon-induced processes remains a daunting challenge for chemists and engineers in the industry, often discouraging their implementation in the production of fine chemicals and pharmaceuticals. To address this key issue, we report herein the development of a conceptually new photochemical reactor, called photo Rotor-Stator Spinning Disk Reactor. The photocatalyzed gas–liquid oxidation of α-terpinene to the drug ascaridole with Rose Bengal as photocatalyst was achieved with throughputs of over 1 kg·day−1 (270 mmol·h−1) under visible light irradiation. The performance of the reactor is correlated to various process parameters such as rotation speed, liquid flowrate, and catalyst concentration, among others. The conversion and selectivity increase from 37% to 97% and 75% to 90% respectively with an increase of rotation speed from 100 to 2000 RPM. The reactor operates with negligible pressure drop and allows for facile fine-tuning of the mixing efficiency. In this paper, we have also compared the performance of this reactor to other reactors such as the batch, micro, thin-film, and the vortex reactor, among others, and have found the photo-Rotor-Stator Spinning Disk Reactor to have superior productivity as well as higher productivity per volume (2.8 mol ·s−1 ·m−3). The findings of this study can be used to study, design, optimize and scale photochemical processes using the rotor–stator spinning disk reactor. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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21. Multiscale modeling of microwave-heated multiphase systems.
- Author
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Goyal, Himanshu and Vlachos, Dionisios G.
- Subjects
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MULTISCALE modeling , *MICROWAVE heating , *ELECTROMAGNETIC fields , *THERMAL conductivity , *SYSTEMS design - Abstract
• Development of a novel multiscale methodology for microwave-heating of multiphase systems. • Verification of the methodology against detailed particle-resolved simulations. • Application of the methodology in optimizing the structure of multiphase systems. • Significant reduction in the requirement of mesh elements and compute time. Modeling of microwave heating of multiphase systems requires resolving the electromagnetic field from the single particle to the entire cavity. We introduce a multiscale methodology for computationally affordable simulations of microwave heating of multiphase systems consisting of one phase dispersed in a continuum phase. The methodology homogenizes the original multiphase system, by taking advantage of the large separation of length scales, to calculate the effective permittivity, effective thermal conductivity, and volumetric power absorbed in each phase. The methodology is rigorously assessed against particle-resolved detailed numerical simulations of model systems. We demonstrate a significant reduction in computational cost while retaining the accuracy of detailed simulations. The present methodology enables high throughput exploration of novel multiphase system designs utilizing microwave heating. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
- Full Text
- View/download PDF
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