Characterization of pressure fluctuations from a gas–solid fluidized bed by structure density function analysis

Chen, Yumin; Lim, C. Jim; Grace, John R.; Zhang, Junying; Zhao, Yuemin; Chen, Zheng

doi:10.1016/j.ces.2015.02.009

Cited by 26 publications

(8 citation statements)

References 38 publications

(64 reference statements)

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“…The passage of bubble through the measuring interval can be properly registered by differential pressure measurements. According to Equation (1), which has been widely used to estimate the pressure drop across the fluidized bed, the average fluctuation amplitude is proportional to the average bubble size [29,30]:…”

Section: Discussionmentioning

confidence: 99%

“…Differential pressure fluctuations are closely correlated with the bubble dynamics between measurement intervals. Thus, they can be favorably applied to characterize the hydrodynamics in different parts of a pilot-scale FBMR [29][30][31]. With the proper resolution of the differential pressure signals by wavelet analysis or other multi-resolution methods, the multiscale dynamics of gas-solid flows could be adequately investigated [29,30].…”

Section: Introductionmentioning

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: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

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 passage of bubbles through the measuring interval can be determined by differential pressure measurements and the fluctuations of the amplitude are proportional to the bubble size . The amplitude of a time series of signals, x i ( i = 1, 2, 3, …, N ), is expressed by the standard deviation as

σ = \sqrt{\frac{1}{N - 1} \sum_{i = 1}^{N} {(x_{i} - x_{italicav})}^{2}}, x_{av} = \frac{1}{N} \sum_{i = 1}^{N} x_{i} .

…”

Section: Methods Of Analysismentioning

confidence: 99%

“…Differential pressure fluctuations are closely correlated with the dynamic flow behavior between the measuring intervals; therefore, pressure measurements are preferred for the characterization of hydrodynamics in different parts of a pilot‐scale FBMR. If the differential pressure signals can be properly resolved using wavelet analysis or other multiscale resolution methods, the multiscale dynamics of gas–solid flows can be investigated …”

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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“…They found that mesoscale signals have two distinct Hurst exponents while microscale and macroscale signals have only one Hurst exponent. Recently, another multiresolution method based on the amplitude of the pressure fluctuation signals was developed by Chen et al Unfortunately, to date the classification as well as the physical meaning of different scales is still not very clear. Besides, almost all the researches have focused on the pressure fluctuations in fluidized bed.…”

Section: Introductionmentioning

confidence: 99%

Multi‐scale analysis of acoustic emission signals in dense‐phase pneumatic conveying of pulverized coal at high pressure

Yang

Huang

et al. 2016

AIChE Journal

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in Wiley Online Library (wileyonlinelibrary.com) Acoustic emission technique in conjunction with multiscale processing method has been utilized to investigate the flow behavior of the dense-phase pneumatic conveying system at high pressure. A clearly defined classification of microscale, mesoscale, and macroscale signals has been put forward with the aid of wavelet transform and V statistics analysis. The detailed signals d 1 -d 4 , d 5 -d 7 , d 8 -d 10 were recomposed into the microscale, mesoscale, and macroscale signals, respectively, which represent microscale particle-wall interactions, mesoscale interaction between gas phase and solid phase (such as bubbles, plugs, dunes), and macroscale flow-induced pipe vibration. Further analysis shows that as the mass flow rate of pulverized coal increases, the energy fraction (energy of detailed signal divided by the energy of original signal) of microscale signals decreases while that of mesoscale signals increases, which indicates that particles are more likely to move as particle aggregates than individual particles when mass flow rate increases.

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Characterization of pressure fluctuations from a gas–solid fluidized bed by structure density function analysis

Cited by 26 publications

References 38 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

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

Multi‐scale analysis of acoustic emission signals in dense‐phase pneumatic conveying of pulverized coal at high pressure

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