Gas permeation effect on the Two-Section Two-Zone Fluidized Bed Membrane Reactor (TS-TZFBMR) fluid dynamics: A CFD simulation study

Julián, Ignacio; Herguido, J.; Menéndez, M.

doi:10.1016/j.cej.2015.08.127

Cited by 10 publications

(7 citation statements)

References 56 publications

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“…Compared to regions above the extraction locations, the bed section below the active membrane panel seemed hardly to be affected by gas extraction, as indicated by only a slight increase of the σ r at DP1 and DP2 with the activation of membranes #2 and #3, respectively. According to studies by Julián et al [22], gas extraction through an immersed tubular membrane or a reactor-wall membrane were also found to exert minor influences on the bubble properties in the region below the permeation zone in a two-section two-zone fluidized bed membrane reactor (TS-TZFBMR). The power spectra of the differential pressure signals measured at DP1, DP2 and DP3 (local bed sections), with gas extracted from membrane #1, #2 and #3, respectively, at a rate of 1.5 L/min, are illustrated in Figure 4.…”

Section: Effects Of Gas Extractionmentioning

confidence: 99%

“…No densified layers were observed during gas extraction when Geldart B type particles (400~600 µm) were used as bed material in experiments conducted by Helmi et al [20]. In addition, with flat membranes installed, both a reduction [20][21][22] and a slight increase [16] in the average bubble size were observed during gas extraction from the fluidized bed. Also, Deshmukh et al [11] experimentally demonstrated that the distributive feeding of oxygen via porous membranes decreased axial gas back-mixing, while the addition of gas through flat membranes was found to increase the gas back-mixing [23].…”

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confidence: 99%

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Analysis of the Hydrodynamic Effects of Gas Permeation in a Pilot-Scale Fluidized Bed Membrane Reactor

et al. 2018

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This study experimentally investigates the effects of gas extraction/addition, via multiple vertical membrane panels, on the hydrodynamics in different regions of a pilot-scale gas fluidized bed membrane reactor (FBMR), based on differential pressure signals measured at different vertical bed sections at high temperature. In a bed section where membrane panels were installed and activated, the extraction of gas caused the average bubble size to increase, but decreased the number of small- and medium-sized bubbles. This effect of gas extraction penetrated into bed sections above the active membrane panel, but attenuated with increasing distance away from the extraction location. The attenuation rate was much faster in FBMR with lower bed voidage, mainly due to the large decrease of the drag force exerted by gas extraction on fluidizing gas in a denser bed. With the same inlet gas velocity, gas addition favored the growth of bubbles, especially in the upper bed sections compared with operation without gas permeation. The increase of the effective fluidizing velocity was the major reason for the increase of the bubble size during gas addition. These findings preliminarily suggest that membrane units should not be installed in or below fast-reacting zones in a scale-up FBMR, and operation with a lower bed voidage is preferable to avoid the formation of large bubbles enhanced by gas extraction.

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Section: Effects Of Gas Extractionmentioning

confidence: 99%

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confidence: 99%

Analysis of the Hydrodynamic Effects of Gas Permeation in a Pilot-Scale Fluidized Bed Membrane Reactor

et al. 2018

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“…The equations can be terminated after constitutive relations have been provided, and these are derived from the empirical statistics or by using the kinetic theory based on granular flow [ 30 , 31 ]. In the ANSYS FLUENT, two different multiphasic models can be obtained, from which the Volume of Fluid (VOF) model and the Eulerian model are used and integrated to form the mathematical models [ 32 , 33 , 34 , 35 , 36 ]. One of the most complicated multiphasic models in the ANSYS FLUENT is the Eulerian model.…”

Section: The Reactions and Kinetic Model For Polymerizationmentioning

confidence: 99%

Multiphasic Reaction Modeling for Polypropylene Production in a Pilot-Scale Catalytic Reactor

2016

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Abstract:In this study, a novel multiphasic model for the calculation of the polypropylene production in a complicated hydrodynamic and the physiochemical environments has been formulated, confirmed and validated. This is a first research attempt that describes the development of the dual-phasic phenomena, the impact of the optimal process conditions on the production rate of polypropylene and the fluidized bed dynamic details which could be concurrently obtained after solving the model coupled with the CFD (computational fluid dynamics) model, the basic mathematical model and the moment equations. Furthermore, we have established the quantitative relationship between the operational condition and the dynamic gas-solid behavior in actual reaction environments. Our results state that the proposed model could be applied for generalizing the production rate of the polymer from a chemical procedure to pilot-scale chemical reaction engineering. However, it was assumed that the solids present in the bubble phase and the reactant gas present in the emulsion phase improved the multiphasic model, thus taking into account that the polymerization took place mutually in the emulsion besides the bubble phase. It was observed that with respect to the experimental extent of the superficial gas velocity and the Ziegler-Natta feed rate, the ratio of the polymer produced as compared to the overall rate of production was approximately in the range of 9%-11%. This is a significant amount and it should not be ignored. We also carried out the simulation studies for comparing the data of the CFD-dependent dual-phasic model, the emulsion phase model, the dynamic bubble model and the experimental results. It was noted that the improved dual-phasic model and the CFD model were able to predict more constricted and safer windows at similar conditions as compared to the experimental results. Our work is unique, as the integrated developed model is able to offer clearer ideas related to the dynamic bed parameters for the separate phases and is also capable of computing the chemical reaction rate for every phase in the reaction. Our improved mutiphasic model revealed similar dynamic behaviour as the conventional model in the initial stages of the polymerization reaction; however, it diverged as time progressed.

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“…On the other hand, Wassie et al experimentally demonstrated that a stable densified zone in the bed consisted of only smaller particles when the gas was extracted via flat vertical membranes placed at the back of the column; this was especially noticeable at high extraction rates. No densified layers were observed during the gas extraction when Geldart B‐type particles (400–600 μm) were used as the bed material in experiments carried out by Helmi et al When flat membranes were installed, both a reduction and a slight increase in the average bubble size were observed during the gas extraction from the fluidized bed. In addition, most available studies on the hydrodynamics of FBMR have been carried out at room temperature .…”

Section: Introductionmentioning

confidence: 99%

“…No densified layers were observed during the gas extraction when Geldart B‐type particles (400–600 μm) were used as the bed material in experiments carried out by Helmi et al When flat membranes were installed, both a reduction and a slight increase in the average bubble size were observed during the gas extraction from the fluidized bed. In addition, most available studies on the hydrodynamics of FBMR have been carried out at room temperature . The characteristics of the bubble phase or emulsion phase in FBMR have been investigated using experimental techniques such as particle image velocimetry, digital image analysis, electrical capacity, magnetic resonance tomography, and optical fiber detection .…”

Section: Introductionmentioning

confidence: 99%

Effect of gas extraction on the hydrodynamics in a fluidized bed membrane reactor at elevated temperatures

Xiao

Chun

Chen

et al. 2019

Asia-Pacific J Chem Eng

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This study describes experimental explorations on the effects of gas extraction on hydrodynamics in a pilot-scalegas fluidized bed membrane reactor (FBMR) at high temperatures. Differential pressure signals were measured at different vertical intervals in bed and were then characterized by multiscale resolution and power spectra analysis. The experimental results showed that the relative amplitude of σ r (σ/x av ) of pressure signal tended todecrease with the increase of gas extraction fraction.At room temperature, 20% gas extraction caused defluidization at an inlet velocity of 2U mf . However, athigh temperatures the gas extraction simultaneously decreased the magnitude of the low-frequency components and the numbers of the medium-to small-sized structures, mainly due to the decreased number of small-sized structures and the integration of bubbles. This effect of gas extraction increased with increase of gas extraction fraction and slightly decreased at higher inlet gas velocities. At elevated temperatures, the D6 sub-signals (0.781~1.562Hz) possessed the highest wavelet energy distribution percentage of the pressure signals, which meant that the medium-to small-sized bubbles dominated the gas-solid flow dynamics. Gas extraction was observed to enhance the dominance of the D6 scale components..

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Gas permeation effect on the Two-Section Two-Zone Fluidized Bed Membrane Reactor (TS-TZFBMR) fluid dynamics: A CFD simulation study

Cited by 10 publications

References 56 publications

Analysis of the Hydrodynamic Effects of Gas Permeation in a Pilot-Scale Fluidized Bed Membrane Reactor

Analysis of the Hydrodynamic Effects of Gas Permeation in a Pilot-Scale Fluidized Bed Membrane Reactor

Multiphasic Reaction Modeling for Polypropylene Production in a Pilot-Scale Catalytic Reactor

Effect of gas extraction on the hydrodynamics in a fluidized bed membrane reactor at elevated temperatures

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