Identification of flow regime in a cocurrent gas – Liquid upflow moving packed bed reactor using gamma ray densitometry

Toukan, Ali; Alexander, Vineet; Albazzaz, Hamza; Al‐Dahhan, Muthanna H.

doi:10.1016/j.ces.2017.04.028

Cited by 18 publications

(16 citation statements)

References 35 publications

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“…Especially at the wall region towards the bottom (Z/D = 0), the gas saturation is very high, indicating the conical bottom is pushing the gas phase towards the wall region. Toukan et al [ 21,22 ] conducted GRD studies on the same reactor and at the same experimental conditions, and observed the radial profile of line average gas holdup at the bottom of the bed (Z/D = 0) shows higher gas holdup at the wall region, which is similar to the observation in this study. The effect of conical bottom on the flow profile distribution is investigated and presented in section 5.…”

Section: Resultssupporting

confidence: 86%

Local hydrodynamics investigation of industrial scaled‐down upflow moving‐bed hydrotreater reactor using a two‐tip optical probe

2021

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Upflow moving‐bed hydrotreater (MBR) is used in refineries as a guard reactor to a fixed‐bed residual desulfurization reactor. Uniform local flow distribution in these reactors is critical to avoid issues like coking, catalyst agglomeration, and hotspots in the catalyst bed. Local maldistribution is investigated on a scaled‐down MBR at a scaled‐down industrial flow condition using an experimental technique called two‐tip optical probe (TTOP), which gives local phase saturations, phase velocities, backmixing, and maldistribution at voids of a two‐phase‐flow packed bed. TTOP implemented at local radial/axial locations indicates highly fluctuating phase saturations inside the catalyst bed, with zones having low‐to‐high gas or liquid saturations, indicating severe local maldistribution. The local phase backmixing and local maldistribution is more on the upper part of the bed.

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Section: Resultssupporting

confidence: 86%

Local hydrodynamics investigation of industrial scaled‐down upflow moving‐bed hydrotreater reactor using a two‐tip optical probe

2021

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“…Further details regarding the application of the maximum likelihood method to calculate the KW have been reported in the literature and can be found in Schouten et al [31]. Toukan et al [40] developed the algorithm and its program in our Multiphase Reactors Engineering and Applications Laboratory (mReal). More details about Kolmogorov entropy's calculation on our FB systems can be found in Taofeeq and Al-Dahhan [6,8].…”

Section: State Space Analysis (Kolmogorov Entropy)mentioning

confidence: 99%

Flow Regimes in Gas‐Solid Fluidized Beds via Micro‐Foil Heat Flux Sensor

2021

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The flow regime transitions in a gas-solid fluidized bed were studied for the first time using a micro-foil heat flux sensor. The time series of heat flux signals was analyzed by statistical and state space methods. The experimental measurements were performed in a lab-scale gas-solid fluidization column. Four different flow regimes, i.e., fixed-bed flow regime, bubbling-flow regime, slugging-flow regime, and turbulent-flow regime, and three intermediate transition velocities, i.e., minimum fluidizing velocity or minimum bubbling velocity, minimum slugging velocity, and minimum turbulent velocity, were successfully identified. The method based on the analysis of heat flux sensor measurements allowed to determine accurately the different flow regimes and the transition velocities.

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“…Therefore, gamma-ray approaches have played a major role and have become the tools of choice in the measurement technology for gas-liquid two-phase systems and gas-liquid-solid three-phase systems [22]. A summary of the literature review on the hydrodynamics studies of upflow packed bed is given elsewhere [23,24]. However, to the best of our knowledge, there are no studies reported in the literature that have studied liquid holdup in two-phase upflow moving beds with a conical bottom.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Liquid Holdup in a Co-Current Gas–Liquid Upflow Moving Packed Bed Reactor with Porous Catalyst Using Gamma-Ray Densitometry

Toukan,

Jasim,

Alexander

et al. 2024

ChemEngineering

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This study explores the dynamics of liquid holdup in a lab-scale co-current two-phase upflow moving packed bed reactor, specifically examining how superficial gas velocity influences the line average external liquid holdup at a fixed superficial liquid velocity. Utilizing gamma-ray densitometry (GRD) for precise measurements, this research extends to determining line average internal porosity within catalyst particles. Conducted with an air–water system within a bed packed with 3 mm porous particles, the study presents a novel methodology using Beer–Lambert’s law to calculate liquid, gas, and solid holdups and catalyst porosity that is equivalent to the internal liquid holdup that fills the catalyst pores. Findings reveal a decrease in liquid holdup corresponding with increased superficial gas velocity across axial and radial locations, with a notable transition from bubbly to pulse flow regime at a critical velocity of 3.8 cm/sec. Additionally, the lower sections of the packed bed exhibited higher external liquid holdup compared to the middle sections at varied gas velocities. The liquid holdup distribution appeared uniform at lower flow rates, whereas higher flow rates favored the middle sections.

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Identification of flow regime in a cocurrent gas – Liquid upflow moving packed bed reactor using gamma ray densitometry

Cited by 18 publications

References 35 publications

Local hydrodynamics investigation of industrial scaled‐down upflow moving‐bed hydrotreater reactor using a two‐tip optical probe

Local hydrodynamics investigation of industrial scaled‐down upflow moving‐bed hydrotreater reactor using a two‐tip optical probe

Flow Regimes in Gas‐Solid Fluidized Beds via Micro‐Foil Heat Flux Sensor

Experimental Investigation of Liquid Holdup in a Co-Current Gas–Liquid Upflow Moving Packed Bed Reactor with Porous Catalyst Using Gamma-Ray Densitometry

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