Hydrodynamic characteristics of reversed flow jet loop reactor as a gas—liquid—solid contactor

Padmavathi, G.; Rao, K. Remananda

doi:10.1016/0009-2509(91)85031-r

Cited by 18 publications

(7 citation statements)

References 3 publications

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“…It means that a certain minimum flow rate is required to achieve the circulation loop. Also Padmavathi and Remananda Rao (1991) discussed the critical liquid velocity, that is, the minimum liquid velocity required for complete circulation of two‐phase flow, but did not report the method to determine it. In all RFJLR's operated at low liquid flow rates, gas–liquid mixture did not come out of draft tube and circulation loop could not be established, until a sufficient superficial liquid velocity in draft tube is available to drag the bubbles up to bottom of draft tube and force them out from draft tube.…”

Section: Introductionsupporting

confidence: 91%

Gas holdup in a two‐phase reversed flow jet loop reactor

et al. 2010

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Experimental investigations have been carried out in Reversed Flow Jet Loop Reactor (RFJLR) to study the influence of liquid flow rate, gas flow rate, immersion height of two-fluid nozzle in reactor and nozzle diameter on gas holdup without circulation, that is, gas-liquid mixture in draft tube only (E gd ) and gas holdup with circulation loop (E g ). Also critical liquid flow rate required for transition from draft tube to circulation loop has been determined. Gas holdup was measured by isolation valve technique. Gas holdup in draft tube and circulation loop increased with increase in liquid flow rate and gas flow rate. It is observed that the increased flow rate is required for achieving a particular value of gas holdup with larger nozzle diameter. Nozzle at the top edge of draft tube have higher gas holdup as compared to other positions. It has been noted that, no significant recirculation of gas bubbles into the top of draft tube from annulus section has been observed till a particular liquid flow rate is reached. A plot of gas holdup with no circulation and with circulation mode determines minimum liquid flow rate required to achieve complete circulation loop. Critical liquid flow rate required to achieve complete circulation loop increases with increase in gas flow rate and is minimum at lowest immersion height of two-fluid nozzle.Des investigations expérimentales ontété effectuées dans un réacteurà jet età boucle de circulationàécoulement inversé pourétudier l'influence du taux d'écoulement du liquide, du taux d'écoulement de gaz, de la hauteur d'immersion de deux busesà fluides dans le réacteur et du diamètre de la buse sur la retenue de gaz sans circulation c.-à-d. le mélange gaz-liquide dans le tube d'aspiration seulement (Egd) et sur la retenue de gaz avec boucle de circulation (Eg). Le taux d'écoulement critique du liquide exigé pour la transition du tube d'aspiration jusqu'à la boucle de circulation aégalementété déterminé. La retenue de gaz aété mesurée en utilisant la technique de vanne d'isolement. La retenue de gaz dans le tube d'aspiration et la boucle de circulation a augmenté avec l'accroissement des taux d'écoulement du liquide et de gaz. Une augmentation substantielle du taux d'écoulement du liquide aété observée pour un même Eg en fonction de l'augmentation du diamètre des buses et la buse se trouvant au bord supérieur du tube d'aspiration a une retenue de gaz plusélevée. Il aété noté qu'aucune recirculation significative de bulles de gaz dans la goulotte de descente de l'espace annulaire n'aété observée jusqu'à ce qu'un taux d'écoulement particulier du liquide ne soit atteint. Un tracé de retenue de gaz avec et sans circulation et détermine le taux minimum d'écoulement de liquide requis pour réaliser une boucle complète de circulation. Le taux minimum d'écoulement requis pour réaliser la boucle complète de circulation augmente avec l'accroissement du taux d'écoulement de gaz et est au minimumà la hauteur minimum d'immersion des deux busesà fluides (Hn = 50 mm).

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Section: Introductionsupporting

confidence: 91%

Gas holdup in a two‐phase reversed flow jet loop reactor

et al. 2010

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“…This type of arrangement has been found to be disadvantageous when the reactor is used as a slurry reactor due to the blockage of the nozzle, and in processes involving sparingly soluble gases due to the lower residence time of the gaseous phase [4,5]. An improved design of JLR [5][6][7] with the two-fluid nozzle at the top of the reactor not only eliminated the blockage of the nozzle but also increased the residence time of the gas in the reactor as the gas bubbles were forced to move against buoyancy. However, in the above investigations the outlet of the liquid was provided at the bottom of the reactor where, only a partial recirculation of liquid takes place as major part of the liquid leaves the reactor without being circulated into the annulus, resulting in a lower residence time of the liquid-phase.…”

Section: Introductionmentioning

confidence: 99%

“…Studies of the fundamental hydrodynamic characteristics in a RFJLR have been made with gas-liquid-solid systems [6,7] and with gas-liquid systems for both Newtonian and nonNewtonian fluids [8,9], but only a little work has been reported on gas-liquid mass transfer [5, 101 with two-phase system, and no work has been reported with three-phase system so far. With the recent development of biotechnology and the extensive use of this type of reactors in fermentation and wastewater treatment, studies on three-phase system are of significant importance.…”

Section: Introductionmentioning

confidence: 99%

Overall volumetric mass transfer coefficient in a modified reversed flow jet loop bioreactor with low density particles

Prasad

Ramanujam

1995

Bioprocess Engineering

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“…Three phase JLRs (gas–liquid–solid) are novel compared to the relatively widely studied gas–liquid bubble column, gas–liquid airlift reactor, gas–liquid JLRs, gas–liquid–solid bubble column, or gas–liquid–solid airlift reactor . Recently, studies on JLRs were mostly relevant to gas–liquid two‐phase flow, while gas–liquid–solid three‐phase systems were rarely studied, in comparison . Fan et al distinguished three flow modes (packed bed, fluidized bed, and circulated bed mode) according to the solids suspension performance in a JLR.…”

Section: Introductionmentioning

confidence: 99%

“…They found the overall gas holdup and liquid circulation velocity increased when the superficial gas and liquid velocity increased. Padmavathi and Rao reported that increasing solids loading and particle density reduced the overall gas holdup and liquid circulation velocity. Some design considerations on JLRs were carried out by Hwang and Fan and Pironti et al, in which they discussed the effect of draft position on overall gas holdup.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on multiscale hydrodynamics in a novel gas–Liquid–Solid three phase jet‐Loop reactor

Gao

et al. 2019

AIChE Journal

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Multiphase flow hydrodynamics in a novel gas–liquid–solid jet‐loop reactor (JLR) were experimentally investigated at the macroscales and mesoscales. The chord length distribution was measured by an optical fiber probe and transformed for bubble size distribution through the maximum entropy method. The impacts of key operating conditions (superficial gas and liquid velocity, solid loading) on hydrodynamics at different axial and radial locations were comprehensively investigated. JLR was found to have good solid suspension ability owing to the internal circulation of bubbles and liquid flow. The gas holdup, axial liquid velocity, and bubble velocity increase with gas velocity, while liquid velocity has little influence on them. Compared with the gas–liquid JLRs, solids decrease the gas holdup and liquid circulation, reduces the bubble velocity and delays the flow development due to the enhanced interaction between bubbles and particles (Stokes number >1). This work also provides a benchmark data for computational fluid dynamics (CFD) model validation. © 2019 American Institute of Chemical Engineers AIChE J, 65: e16537, 2019

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Hydrodynamic characteristics of reversed flow jet loop reactor as a gas—liquid—solid contactor

Cited by 18 publications

References 3 publications

Gas holdup in a two‐phase reversed flow jet loop reactor

Gas holdup in a two‐phase reversed flow jet loop reactor

Overall volumetric mass transfer coefficient in a modified reversed flow jet loop bioreactor with low density particles

Experimental investigation on multiscale hydrodynamics in a novel gas–Liquid–Solid three phase jet‐Loop reactor

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