Three-dimensional void space structure of activated carbon packed beds

Almazán-Almazán, M.C.; Léonard, Angélique; Job, Nathalie; López-Garzón, J.; Pirard, Jean‐Paul; Blacher, Silvia

doi:10.1007/s10934-010-9438-5

Cited by 4 publications

(2 citation statements)

References 23 publications

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“…Such patterns are typically represented through sinusoidal functions or similar periodic models. 29,30 At the position of 75 mm, due to the wall effect, the void fraction distribution is low in the middle and high at both ends. At this point, there is almost no difference in the central area of the bed, while a large number of bubbles gather near the wall.…”

Section: Results and Analysismentioning

confidence: 99%

Study on Gas–Solid Flow Characteristics in Fluidized Bed Membrane Reactors with Different Membrane Tube Arrangements Using X-ray Computed Tomography

Mei,

Chen,

Xiang

2024

Ind. Eng. Chem. Res.

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Fluidized bed membrane reactors have been introduced in catalytic reforming hydrogen production recently. The arrangement of membrane tubes is the key factor in the gas–solid distribution in reactors, which decides the production efficiency and wearing characteristics of membrane tubes. Nevertheless, research on optimization of the arrangement of membrane tubes is still inadequate due to a lack of measuring methods which can penetrate solid particles and internal components. In this study, the time-averaged void fraction distributions inside fluidized bed membrane reactors with different fluidization velocities and tube layouts are investigated using X-ray computed tomography. The effects of spacers on the internal gas–solid flow characteristics are studied as well. The results indicate that bubbles first gather toward the bed center axis during rising, then cut by the tube bundle, causing bubbles to split and then aggregate. Increasing the number of bundles makes the distribution of bubbles more uniform. The spacer allows more bubbles to move along the wall, and these bubbles tend to return to the middle of the fluidized bed after passing through the spacer, leading to more particle aggregation around the spacer. Using a multibundle spacer can reduce aggregation. As the bed height increases, the void fraction at the wall of the fluidized bed is less affected by the number of tube bundles, and the use of spacers strengthens the positive impact of the number of tube bundles. As the fluidization velocity increases, bubbles gather toward the bed center. The presence of tube bundles will cause the accumulation of bubbles to be more rapid.

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Section: Results and Analysismentioning

confidence: 99%

Study on Gas–Solid Flow Characteristics in Fluidized Bed Membrane Reactors with Different Membrane Tube Arrangements Using X-ray Computed Tomography

Mei,

Chen,

Xiang

2024

Ind. Eng. Chem. Res.

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“…The proposed measurement procedure used a closed impermeable system in which only the temperature was controlled while the total liquid water vapor content remained constant. The three-dimensional structure of the void space formed during the placement of active carbon grains was found to have a greater effect on the filter efficiency due to the change in the transport properties within the layer [23]. Image analysis algorithms allowing for the determination of the total void fraction, the void size distribution and the radial void fraction profiles were developed.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Structure and Diffusion of Porous Layers

Satayev,

Azimov,

Iztleuov

et al. 2024

Water

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The aim of this work is to develop an adsorber with a fixed bed of adsorbent and a mathematical model of the adsorption bed. On the basis of the theory of fractal clusters, an equation for calculating the layer porosity that takes into account the average cluster radius, the fractal dimension of the cluster structure and the anisotropy index of the adsorbent layer is proposed. The adsorption mechanism in the layer was established, and the proportionality coefficients were estimated based on the tetrahedral packing of grains in the layer. Based on the analysis of the movement of the carrier through the adsorption layer and its deformation, an equation that describes the change in the porosity of the granular layer when the water flow moves through it, depending on the proportionality coefficients, is proposed. An equation that made it possible to calculate the change in the porosity of the layer in comparison with the porosity of the stationary stacking was obtained. An effective design for the adsorber that made it possible to increase the efficiency of using the structure of porous adsorption layers was developed. Equations of the heat and mass transfer taking into account the granule shape coefficient, effective diffusion coefficient and mass transfer coefficient were derived. These equations establish the relationship between the average distance between active centers on the adsorption surface and the degree of filling of the adsorption surface with the adsorbed component.

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