Method to concurrently measure local gas and solid holdups visually with higher precision in circulating fluidized bed

Zhang, Lubin; Ma, Yong-li; Zhang, Jiaming; Liu, Mingyan

doi:10.1002/aic.17510

Cited by 5 publications

(5 citation statements)

References 31 publications

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“…There is a need to develop a new recognition program to improve the efficiency of bubble recognition. Of course, its precision also needs to be further improved, and some results have been achieved …”

Section: Discussionmentioning

confidence: 99%

Measurements of Local Flow Characteristics in a Gas–Liquid–Solid Circulating Fluidized Bed with Immersed Telocentric Photography

Zhang

Liu

et al. 2022

Ind. Eng. Chem. Res.

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The gas bubble size, local phase holdup, and other local flow characteristic parameters of the gas–liquid–solid circulating fluidized bed play an important role in the design and operation of this type of reactor. However, due to the limitation of measurement techniques of three-phase fluidization, the local flow characteristics have not been well measured and studied. In recent years, telecentric imaging technology has been applied in other multiphase systems, and a new telecentric probe method has been used to measure the local flow characteristics of a gas–liquid–solid expanded bed. In this work, the measuring method was introduced to measure the local phase holdups and bubble size distributions of the three-phase circulating fluidized bed. Concurrently, the influence of the superficial liquid and gas velocities on the particle circulation rate in the three-phase circulating fluidized bed was studied. The method reliability of gas holdup and bubble size measurements was validated by a conductivity probe method. The results provided basic data of such a reactor for future flow numerical simulations and industrial applications.

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Section: Discussionmentioning

confidence: 99%

Measurements of Local Flow Characteristics in a Gas–Liquid–Solid Circulating Fluidized Bed with Immersed Telocentric Photography

Zhang

Liu

et al. 2022

Ind. Eng. Chem. Res.

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“…In the gas-liquid-solid three-phase fluidized bed, solid clusters and bubble clusters are generated due to the nonuniform distribution of the three phases [10,11]. Clusters can lead to a decrease in contact efficiency or mass transfer, so detecting the cluster distribution is particularly important for the reaction process [12].…”

Section: Introductionmentioning

confidence: 99%

An approach to solving the effect of background in fluidized bed on electromagnetic tomography

Luan,

Wang,

Liang

2024

Meas. Sci. Technol.

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As a non-invasive measurement technique, electromagnetic tomography (EMT) system based on tunneling magneto resistance (TMR) can detect the distribution of medium in the gas-liquid-solid fluidized bed by the difference of permeability. The distribution of medium in the three-phase fluidized bed is not uniform, and the solid clusters and bubble clusters are formed in the background of the gas-liquid-solid mixture. Since the effect of the background in the pipe of the fluidized bed on the boundary measurement data of the TMR-EMT system is much greater, it is difficult to detect solid clusters and bubble clusters when the image is reconstructed directly using the boundary measurement data. In order to improve the detection of clusters by the TMR-EMT system, a method to weaken the effect of the background is proposed. The equivalent magnetic circuit model is used to estimate the background permeability. Then the magnetic dipole theory and demagnetization effect theory are utilized to establish a simple background compensation model based on the estimated background permeability. Using the compensation model, the effect of the background is weakened from the boundary measurement data and the cluster distribution information is highlighted. Simulation and experimental results demonstrate the effectiveness of the proposed method.

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“…With the development of multiphase flow measurement technology, the image-based method, − optical fiber probe, conductivity probe, tomographic methods, etc. can now be utilized to acquire the bubble size distribution and the dispersed phase holdup distribution, which provides favorable conditions for understanding the local hydrodynamic characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…However, this method encounters some challenges, such as particle identification within the depth of field, dim bubble extraction, and counting overlapping particles. 13 Therefore, it is still a difficult task to count the BSD in gas−liquid−solid three-phase systems due to the complexity of the fluid motion and various interactions among phases. 31 Lee et al 11 utilized PIV to investigate the BSD in a slurry bubble column and found that small bubbles had to be considered when evaluating the bimodal bubble size distribution.…”

Section: Introductionmentioning

confidence: 99%

“…The image-based method not only enables the statistical analysis of the BSD and the local phase holdup but also allows for the identification of the shape and number of dispersed phases. However, this method encounters some challenges, such as particle identification within the depth of field, dim bubble extraction, and counting overlapping particles . Therefore, it is still a difficult task to count the BSD in gas–liquid–solid three-phase systems due to the complexity of the fluid motion and various interactions among phases .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of the Gas–Liquid–Solid Stirred Tank by Using the Intrusive Image-Based Method

Wang,

Duan,

Feng

et al. 2023

Ind. Eng. Chem. Res.

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This work investigates the effect of solid particles on bubble size distribution and dispersed phase holdup in a stirred tank with the invasive telecentric photographic measurement system. The bubbles and solid particles are efficiently identified and distinguished with the image processing mainly based on deep learning and two different magnifications of telecentric lenses. The results show that solid particles promote the coalescence of bubbles, particularly at high solid concentrations. However, small bubbles (<1 mm) still dominate in number density, but their volume proportions are less than 3%. The Sauter mean diameter of bubbles (d 32 ) does not always increase monotonously with the increase in solid concentration. For small particles, the increment in d 32 is more pronounced due to a better solid suspension and a higher local effective viscosity, which further results in a lower local gas holdup. To summarize, the developed measurement method for the gas−liquid−solid system in this work provides valuable insights into the hydrodynamics in a stirred tank.

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Method to concurrently measure local gas and solid holdups visually with higher precision in circulating fluidized bed

Cited by 5 publications

References 31 publications

Measurements of Local Flow Characteristics in a Gas–Liquid–Solid Circulating Fluidized Bed with Immersed Telocentric Photography

Measurements of Local Flow Characteristics in a Gas–Liquid–Solid Circulating Fluidized Bed with Immersed Telocentric Photography

An approach to solving the effect of background in fluidized bed on electromagnetic tomography

Investigation of the Gas–Liquid–Solid Stirred Tank by Using the Intrusive Image-Based Method

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