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Circulating turbulent fluidization-A new fluidization regime or just a transitional phenomenon

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Particuology 2010年第6期8卷 640-644页

作者： jesse Zhu Particle Technology Research Centre and Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioN6A 5B9Canada

While circulating fluidized bed （CFB） reactor has many advantages over the more conventional turbulent fluidized bed （TFB） reactor, it does at least have one significant shortcoming-the rather dilute solids volume concentration in CFB reactor gives rise to less ideal reaction intensity. On the other hand, while having higher reaction intensity, TFB reactor has one fatal drawback of particle back-mixing, making it not suitable for certain reactions such as catalytic reaction where the catalyst requires frequent regeneration. This paper describes some key issues in the development of a circulating turbulent fluidized bed （CTFB） reactor that combines the advantages of both TFB and CFB, that is, to have the high reaction intensity as in TFB but and also to have a suppressed solids back-mixing as in CFB due to a continuous net upflow of solids flux through the bed. Experimental results show enough evidence to suggest that a new fluidization regime is formed, the characteristics of which appears to be distinct from those observed in a regular TFB and from those in either the bottom or the upper sections of regular CFB and/or high-density CFB （HDCFB）. Fundamentally, the difference is that particle-particle interaction （collision） dominates the motion of particles in CTFB and TFB, while gas-particle interaction （drag force） is the key element that determines the two phase flow in CFB including HDCFB.

关键词： Circulating-turbulent fluidized bed Flow regime Circulating-turbulent fluidizationTurbulent fluidized bed Circulating fluidized bed

Experimental 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 examined 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 mixing 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 backmixing 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

Preamble for special issue honouring Professor Mooson Kwauk

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Particuology 2010年第6期8卷 491-492页

作者： jesse Zhu Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioCanada N6A 5B9

Two years after assuming a new name and format change, the year 2010 marks the 8th anniversary of Particuology. To commemorate this special occasion for the journal, the thematic editors met in Montreal at the 8th World Congress of Chemical Engineering and decided to compile a truly special issue. Instead of producing another ＂conventional＂ special issue of the more ＂regular＂ research papers on some given subjects, we have decided to take a more innovative format for this issue to present short discussion papers that provide quick overviews of the current status of selected subiects and then discuss forward thinking for the future.

关键词： Preamble for special issue honouring Professor Mooson Kwauk EMMS very

Cluster identification using image processing

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Particuology 2015年第6期13卷 16-24页

作者： Jingsi Yang jesse Zhu Particle Technology Research Centre Department of Chemical and Biochemical Engineering University of Western Ontario London Ontario N6A 5B9Canada

By closely examining hue, saturation and value （HSV） images of the solids holdup distribution in a riser, it can be seen that a ＂cluster＂ is the combination of a relatively stable core cluster of the highest solids holdups and constantly changing cluster clouds of solids holdups that are higher than the dilute phase. Based on this analysis, a threshold selection method maximizing the inter-class variance between the background and foreground classes is introduced. A systematic cluster identification process is therefore proposed that：（｜） applies the threshold selection method to obtain the critical solids holdup threshold ~c to discriminate dense and dilute phases and （2） applies the method again in the dense phase regions to obtain the cluster solids holdup threshold Ssct that identifies the core clusters. Using this systematic process, clusters of different shapes and sizes and a relatively clear boundary can be visualized clearly and identified accurately. Using ~sct, the core cluster fraction is calculated by dividing the total number of pixels in the core cluster by the total number of image pixels. The variation of the core cluster fraction according to operating conditions is also discussed.

关键词： Cluster identification Image processingCluster fractionRectangular circulating fluidized bed riser

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 experimental 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

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 Excellence 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 mixed with the cohesive fine/ultrafine *** nano-modulation,the fluidization system of cohesive powders exhibits distinguishable minimum fluidization velocity,enlarged bed expansion ratio(particularly the dense phase expansion),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

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 exchange of chemical science and *** addition to its key roles in international academic exchanges 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 Excellent 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

Special Issue for the 14th Global Chinese Chemical Engineering Symposium

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Frontiers of Chemical Science and Engineering 2023年第10期17卷 1321-1322页

The Global Chinese Chemical Engineering Symposium(GCCES)is a prestigious and world-wide platform for the communication and academic exchange of chemical science and *** special issue is a collection of the keynote lectures presented by the winners of Future Chemical Engineering Scholars,the Global Award for Outstanding Young Female Chemical Engineers,and the International Award for Outstanding Young Chemical Engineers,selected by the International Scientific Committee of the GCCES.

关键词： engineering. Global Engineers

Evaluation of the effect of wall boundary conditions on numerical simulations of circulating fluidized beds

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Particuology 2014年第2期12卷 114-123页

作者： Lei Kong Chao Zhang jesse Zhu Department of Mechanical and Materials Engineering The University of Western OntarioLondonOntarioN6A 5B9Canada Department of Chemical and Biochemical Engineering The University of Western OntarioLondonOntarioN6A 5B9Canada

A computational fluid dynamics （CFD） modeling of the gas-solids two-phase flow in a circulating fluidized bed （CFB） riser is carried out. The Eularian-Eularian method with the kinetic theory of granular flow is used to solve the gas-solids two-phase flow in the CFB riser. The wall boundary condition of the riser is defined based on the Johnson and Jackson wall boundary theory （Johnson ＆ Jackson, 1987） with specularity coefficient and particle-wall restitution *** numerical results show that these two coefficients in the wall boundary condition play a major role in the predicted solids lateral velocity, which affects the solid particle distribution in the CFB riser. And the effect of each of the two coefficients on the solids distribution also depends on the other one. The generality of the CFD model is further validated under different operatin~ conditions of the CFB riser.

关键词： CFD Circulating fluidized bed Gas-solids two-phase flowWall boundary conditionSpecularity coefficientParticle-wall restitution coefficient