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Micro-flow structure at regime transition from bubbling to turbulent fluidization in a fluidized bed

Particuology 2024年第6期89卷 117-130页

作者： Chaoyu Yan Yue Yuan x.aoyang Wei jesse zhu State Key Laboratory of Heavy Oil Processing Beijing Key Laboratory of Process Fluid Filtration and SeparationCollege of Mechanical and Transportation EngineeringChina University of PetroleumBeijing 102249China China Beacons Institute The University of NottinghamNingbo315100China Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioN6A 5B9Canada

Gas-solid fluidized beds have found ex.ensive utilization in frontline manufacturing,in particular as low-velocity *** fluidization status,the bubbling or turbulent flow regime and the transition in between,determine the system performance in practical *** the convoluted hydrodynamics are quantitively evaluated through numerous data-processing methodologies,none of them alone can reflect all the critical information to identify the transition from the bubbling to the turbulent ***,this study was to ex.loit a coupling data processing methodology,in the combination of standard deviation,power spectrum density,probability density function,wavelet transform,and wavelet multiresolution method,to jointly ex.lain the micro-flow structure at the regime transition from bubbling to turbulent *** transient differential pressure fluctuation was measured for the evaluation in a fluidized bed(0.267 m i.d.×2.5 m height)with FCC catalysts(d_(p)=65μm,ρ_(p)=1780kg/m^(3))at different superficial gas velocities(0.02–1.4 m/s).The results show that the onset of turbulent fluidization starts earlier in the top section of the bed than in the bottom *** wavelet decomposition displays that the fluctuation of differential pressure mainly concentrates on the sub-signals with an intermediate frequency *** sub-signals could be synthesized into three types of scales(micro-scale,meso-scale,and macro-scale),representing the multi-scale hydrodynamics in the fluidized *** micro-scale signal has the characteristic information of bubbling fluidization,and the characteristic information of turbulent fluidization is mainly represented by the meso-scale *** work provides a systematic comprehension of fluidization status assessment and serves as an impetus for more coupling analysis in this sector.

关键词： Flow regime transition Bubbling fluidization Turbulent fluidization Micro-flow structure Differential pressure fluctuation

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Analysis of Flow Dynamics in the High-Flux.Gas-Solid Riser Using Trajectory Distances across Attractors Reconstructed from Solid Concentration Signals

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Engineering（科研） 2018年第10期10卷 688-703页

作者： Justin M. Jeremiah Samwel V. Manyele Abraham K. Temu jesse-x. zhu Department of Chemical and Mining Engineering University of Dar es Salaam Dar es Salaam Tanzania Department of Chemical and Biochemical Engineering University of Western Ontario London ON Canada

The study of the entrance and wall dynamics of a high-flux.gas-solid riser was conducted using trajectory distances of the reconstructed attractors from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analyzed using codes prepared in FORTRAN 2008 to get trajectories of the reconstructed attractors and their distances apart. Trajectory distances were found to increase from the centre towards the wall indicating the ex.ansion of the attractor. The probability density function (PDF) of the trajectory distances changes from single peak at the centre to multiple peaked profiles in the wall region. Multiple peaked profiles indicate multifractal flow behaviours. Cumulative distribution functions (CDF) of the trajectory distances changes from single S-shaped at the centre to multiple S-shaped profiles in some locations of the wall region indicating multifractal flow behaviours. The PDF distribution of these distances at the entrance section and in the wall region forms different types of statistical distributions showing differences in gas-solid flow structures in various spatial locations of the wall region and the entrance sections. Most of the distributions at the centre fall under the Gumbel max.distribution for all flow development sections of the riser, especially at air velocities of 5.5 m/s and 8 m/s showing uniform flow structures. Further, it was found that increase of the number of the phase space reconstruction embedding dimension increases the trajectory distances between the state vectors leading to the ex.ansion of the attractor.

关键词： Trajectory Distance Probability Density Function Cumulative Distribution Function Euclidian Distance High-Flux Riser

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Investigation of Entrance and Wall Dynamics of the High-Flux.Gas-Solid Riser Using Statistical Analysis of Solids Concentration Signals

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Engineering（科研） 2019年第3期11卷 167-187页

Statistical analysis of the entrance and wall dynamics of a high-flux.gas-solid riser was done using solid concentration time series data collected from a 76 mm internal diameter and 10 m high riser of a CFB system with a twin-riser operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analysed using code prepared using FORTRAN 2008 to get statistical parameters and plot their profiles. Results obtained show that the gas-solid suspension flow in the riser is dominated by low solid concentration in the centre region and high solid concentration in the wall region which forms a core-annulus flow structure. The mean solid concentration in the wall region decreases with riser height from the dense bottom section to less dense in the fully developed flow section at the top of the riser. The gas-solid suspension flow in the centre region is dominated with uniform flow structure while the wall region is dominated with high fluctuations in solid concentration. Further, it was found that the entrance and developing flow sections of the riser ex.ibit high flow non-uniformities than the fully developed flow section of the riser. The flow non-uniformities in the entrance and developing flow section increase with increase in superficial gas velocity at constant solid flux. The wall region, from the entrance to the top sections of the riser along the ax.al direction ex.ibits both dilute and dense suspension flow.

关键词： Entrance Section Wall Region Statistical Analysis Flow Non-Uniformities Radial Non-Uniformity Index

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Mapping Correlation Dimension along the Wall Region of a High-Flux.Gas-Solid Riser Using Embedded Solid Concentration Time Series

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Engineering（科研） 2018年第10期10卷 655-679页

Analysis of the entrance and wall dynamics of a high-flux.gas-solid riser was conducted using embedded solid concentration time series collected from a 76 mm internal diameter and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s air velocity and 50 to 550 kg/m2s solids flux.of spent fluid catalytic cracking (FCC) catalyst particles with 67 μm mean diameter and density of 1500 kg/m3. Data were analyzed using prepared FORTRAN 2008 code to get correlation integral followed by determination of correlation dimensions with respect to the hyperspherical radius and their profiles, plots of which were studied. It was found that correlation dimension profiles at the centre have single peak with higher values than the wall region profiles. Towards the wall, these profiles have double or multiple peaks showing bifractal or multifractal flow behaviors. As the velocity increases the wall region profiles become random and irregular. Further it was found that, as the height increases the correlation dimension profiles shift towards higher hyperspherical radius at the centre and towards lower hyperspherical radius in the wall region at r/R = 0.81. The established method of mapping correlation dimension profiles in this study forms a suitable tool for analysis of high-flux.riser dynamics compared to other analyses approaches. However, further analysis is recommended to other gas-solid CFB riser of different dimensions operated at high-flux.conditions using the established method.

关键词： Correlation Integral Mapping Correlation Dimension High-Flux Gas-Solid Riser Embedded Solid Concentration Time Series

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Mapping the Wall-Region Dynamics of High-Flux.Gas-Solid Riser Using Scaling Regions from the Solid Concentration Time Series

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Engineering（科研） 2019年第1期11卷 74-92页

An ex.erimental study of the gas-solid flow dynamics in the high-flux.CFB riser was accomplished by analysing the scaling regions from solid concentration signals collected from a 76 mm internal diameters and 10 m high riser of a circulating fluidized bed (CFB) system. The riser was operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking (FCC) catalyst particles of 67 μm mean diameter and 1500 kg/m3 density together with 70% to 80% humid air was used. Solid concentration data were analysed using codes prepared in FORTRAN 2008 to get correlation integrals at different embedding dimensions and operating conditions and plot their profiles. Scaling regions were identified by visual inspection method and their location on planes determined. Scaling regions were analysed based on operating conditions and riser spatial locations. It was found that scaling regions occupy different locations on the plane depending on the number of embedding dimensions and operating conditions. As the number of embedding dimensions increases the spacing between scaling regions decreases until it saturates towards higher embedding dimensions. Slopes of scaling regions increases with embedding dimensions until saturation where they become constant. Slopes of scaling regions towards the wall decrease while the number of scaling regions for a particular profile increases. The span of the scaling region is wider at the initial values of hyperspherical radius than its final values. The scaling regions in some flow development sections show multifractal behaviour for each embedding dimension which manifests into visible basin which is defined in this study as multifractal basin. Further, the end points of the scaling region for each correlation integral profile differ from each other as the embedding dimension changes. This study suggests that identification of scaling region by visual inspection method is useful in understanding the gas-solid flow d

关键词： Scaling Region Correlation Integral Correlation Dimension Embedding Dimensions Multifractal Basin High-Flux Riser

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Ex.erimental study on reactor performance of gas-solids low-velocity fluidized beds

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Particuology 2022年第7期20卷 21-28页

作者： Jiangshan Liu jesse zhu Particle Technology Research Centre Department of Chemical and Biochemical EngineeringThe University of Western OntarioLondonOntarioN6A 3K7Canada

Reactor performance of bubbling fluidized bed(BFB)and turbulent fluidized bed(TFB)was carefully ex.mined and systematically compared using catalytic ozone decomposition as a model reaction,based on a complete mapping of local flow structures and spatial distributions of ozone conversion and solids *** clearly has a higher conversion and shows better reactor performance than BFB as a result of the vigorously turbulent flow and the relatively homogeneous gas–solids mix.ng in ***,the intensive interaction between gas and solids in TFB leads to greater gas–solids contact efficiency of TFB over that of *** to gas bypassing and backmix.ng caused by bubbling behaviours and two-phase structure,BFB deviates significantly from a plug flow reactor and sometimes from a continuously stirred tank *** flow structures essentially dictate the reactor performance in the low-velocity fluidized beds.

关键词： Bubbling fluidized bed Turbulent fluidized bed Conversion distribution Flow structure Reactor performance Gas–solids contact efficiency

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Intelligent Intercommunicating Multiscale Engineering: The Engineering of the Future

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Engineering 2023年第11期30卷 13-19页

作者： Yue Yuan jesse zhu China Beacons Institute The University of NottinghamNingbo 315100China Particle Technology Research Center Department of Chemical and Biochemical EngineeringThe University of Western OntarioLondonON N6A 5B9Canada

*** Despite being widely known and investigated as a computer science discipline,artificial intelligence(AI)has attracted incomparable interest from researchers in diversified areas[1].In 1950,Alan Turing raised the classic question that has inspired numerous researchers to date:“Can machines think?”[2].The ultimate benchmark of AI was set by Turing’s revised“imitation game.”

关键词： computer artificial Turing

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Numerical investigations on gas-solid flow in circulating fluidized bed risers using a new cluster-based drag model

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Particuology 2022年第4期20卷 9-23页

作者： Zeneng Sun Chao Zhang jesse zhu Department of Chemical and Biochemical Engineering.The University of Western Ontario LondonOntarioN6A 3K7Canada Department of Mechanical and Materials Engineering The University of Western OntarioLondonOntarioN6A 3K7Canada

A cluster-based drag model is proposed for the gas-solid circulating fluidized bed(CFB)riser by including the cluster information collected from image processing and wavelet analysis into the calculation of system *** performance of the proposed drag model is compared with some commonly used drag models.A good agreement with the ex.erimental data is achieved by the proposed cluster-based drag *** analysis of the proposed cluster-based drag model based on the local distributions of solids holdup and particle velocity is *** clustering phenomenon in the low-density and high-density CFB risers and the effect of the cluster size on the simulation accuracy are also numerically studied by the proposed drag model.

关键词： Drag model Clustering effect Gas-solid flow structures Circulating fluidized bed

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Improving flow and fluidization quality of fine and ultrafine particles via nanoparticle modulation

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Nano Research 2023年第10期16卷 12013-12025页

作者： Jiaying Wang Yuanyuan Shao jesse zhu Department of Chemical and Biochemical Engineering The University of Western OntarioLondonOntario N6A 3K7Canada School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Beacons of Ex.ellence Research and Innovation Institute University of NottinghamNingbo 315100China

Fine and ultrafine particles possess great potential for industrial applications ascribed from their huge specific surface area and ability to provide good gas–solid ***,these powders are inherently cohesive,making it challenging to achieve smooth flow and *** challenge can be well-resolved by nanoparticle modulation(nano-modulation),where a small amount of nanoparticles is uniformly mix.d with the cohesive fine/ultrafine *** nano-modulation,the fluidization system of cohesive powders ex.ibits distinguishable minimum fluidization velocity,enlarged bed ex.ansion ratio(particularly the dense phase ex.ansion),and scarcer,smaller,and slower moving bubbles,indicating improved flow and fluidization *** purpose of the current work is to systematically summarize the state-of-the-art progress in the fluidization and utilization of fine and ultrafine particles via the nanoparticle modulation ***,a broader audience can be enlightened regarding this promising fine/ultrafine particle fluidization technology,so as to provoke their attention and encourage interdisciplinary integration and industry-academia collaborative research.

关键词： fine particle ultrafine particle cohesive powder flowability fluidization nanoparticle modulation

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Special Issue for the Future Chemical Engineering Scholars of Global Chinese Chemical Engineering Symposium

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Frontiers of Chemical Science and Engineering 2022年第6期16卷 775-776页

作者： jesse zhu Junwu Wang Particle Technology Research Centre Western UniversityLondonOntario N6A 5B9Canada State Key Laboratory of Multiphase Complex.Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China

The Global Chinese Chemical Engineering Symposium(GCCES)is a prestigious and world-wide platform for the communication and academic ex.hange of chemical science and *** addition to its key roles in international academic ex.hanges and collaborations,as well as cross-disciplinary integration and industrial-academic co-operation,the GCCES strongly promotes the professional development of young Chinese chemical engineers and scientists by founding series of special forums for the winners of the Ex.ellent Postgraduate Academic Forum,the Young Researchers Forum,the Future Chemical Engineering Scholars,and the International Award for Outstanding Young Chemical Engineers.

关键词： founding Global Scholars

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