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Decarburization Thermodynamics of High-Carbon Ferromanganese Powders During gas-solid fluidization Process

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Journal of Iron and Steel Research International 2012年第5期19卷 1-8页

作者： GUO Li-na CHEN Jin ZHANG Meng LIANG Min College of Materials Science and Engineering Taiyuan University of Technology Taiyuan 030024 Shanxi China

Thermodynamic conditions of reactions between high-carbon ferromanganese powders and gas decarbonizers like O2, CO2 and water vapor were studied by thermodynamic calculation. In O2, CO2 and water vapor atmosphere, high-carbon ferromanganese powders were decarburized in a fluidized bed. When the temperature is respectively higher than 273, 1 226 and 1 312 K, the gas-solid decarburization reaction will occur between ferromanganese carbide on the surface of the high-carbon ferromanganese powders and different gas decarbonizers. Since metal manganese is easy to be oxidized by O2, CO2 or water vapor, the decarburization reaction will transfer into a solid-solid phase reaction of ferromanganese carbide and ferromanganese oxide, promoting external diffusion of carbon to achieve a further decarburization of high-carbon ferromanganese powders.

关键词： gas-solid fluidization high carbon ferromanganese powders gas decarbonizer solid-phase decarburization

Energy budget of cold and hot gas-solid fluidized beds through CFD-DEM simulations

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Particuology 2024年第6期89卷 153-171页

作者： Lei Bi Yunpeng Jiao Chunjiang Liu Jianhua Chen Wei Ge School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

Direct energy budget is carried out for both cold and hot flow in gas–solid fluidization ***,the energy paths are proposed from thermodynamic *** consumption means total power input to the specific system,and it can be decomposed into energy retention and energy *** retention is the variation of accumulated mechanical energy in the system,and energy dissipation is the energy converted to heat by irreversible *** based on the Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)framework,different energy terms are quantified from the specific flow elements of fluid cells and particles as well as their interactions with the *** order to clarify the energy budget,it is important to identify which system is studied:the particle-fluid system or the particle *** the cold flow,the total energy consumption of the particle sub-system can well indicate the onset of bubbling and turbulent,while the variation of local energy consumption terms can reflect the evolution of heterogeneous *** the hot flow,different heat transfer mechanisms are analyzed and the solver is modified to reproduce the experimental *** impact of the heat transfer mechanisms and heat production on energy consumption is also *** proposed budget method has proven to be energy-conservative and easy to conduct,and it is hopeful to be applied to other multiphase flow systems.

关键词： Energy budget gas-solid fluidization CFD-DEM Regime transition Heat transfer mechanism

fluidization behavior of graphitized glassy particles in a fluidized carbon bed cooling process for investment casting

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Particuology 2022年第6期20卷 32-38页

作者： Paul Git Matthias Hofmeister Robert F.Singer Carolin Körner Chair of Materials Science and Engineering for Metals(WTM) Friedrich-Alexander UniversitätErlangen-Nürnberg(FAU)Martensstr.591058 ErlangenGermany

Fluidized Carbon Bed Cooling(FCBC)is an innovative investment casting process for directional solidification of superalloy *** takes advantage of a fluidized bed with a base of small glassy carbon beads for cooling and other low-density particles that form an insulating layer by floating to the bed *** so-called“Dynamic Baffle”protects the fluidized bed from the direct heat input from the high-temperature heating zone and provides the basis for an improved bed *** prerequisites for a stable casting process are stable fluidization conditions where neither collapse of the bed nor particle blow out at excessive bubble formation *** work aimed to investigate the fluidization behavior of spherical carbon bed material in argon and air at temperatures between 20 to 350℃.Systematic studies at reduced pressures using the FCBC prototype device were performed to understand the stable fluidization conditions at all stages of the investment casting *** particle shape factor and size distribution characterization and the measurement of the powder’s minimum fluidization velocity and bed voidage show that this material can be fully utilized as a cooling and buoyancy medium during the FCBC process.

关键词： gas-solid fluidization Glassy carbon Reduced pressure Increased temperature Fluidized carbon bed

Bed dynamics of gas-solid fluidized bed with rod promoter

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China Particuology 2007年第4期5卷 261-266页

作者： Awadhesh Kumar Gopendra K.Roy Department of Civil Engineering National Institute of TechnologyRourkela 769008OrissaIndia Department of Chemical Engineering National Institute of TechnologyRourkela 769008OrissaIndia

The dynamic characteristics of a gas-solid fluidized bed with different rod promoters have been investigated in terms of bed expansion and fluctuation, minimum fluidization velocity and distributor-to-bed pressure drop ratio at minimum fluidization velocity. Experimentation based on statistical design has been carried out and model equations using factorial design of experiments have been developed for the above mentioned quantities for a promoted gas-solid fluidized bed. The model equations have been tested with additional experimental data. The system variables include four types of rod promoters of varying blockage volume, bed particles of four sizes and four initial static bed heights. A comparison between the predicted values of the output variables using the proposed model equation with their corresponding experimental ones shows fairly good agreement.

关键词： Dynamic characteristics Statistical design gas-solid fluidization Rod promoter

Segregation characteristics of irregular binaries in gas solid fluidized beds——An ANN-approach

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Particuology 2008年第3期6卷 199-206页

作者： Abanti Sahoo Gopendra Kishore Roy Department of Chemical Engineering National Institute of TechnologyRourkela769008 OrissaIndia

Binary mixtures of irregular materials of different particle sizes and/or particle densities are fluidized in a 15-cm diameter column with a perforated plate distributor. An attempt has been made in this work to determine the segregation characteristics of jetsam particles for both the homogeneous and heterogeneous binary mixtures in terms of segregation distance by correlating it to the various system parameters, viz. initial static bed height, height of a layer of particles above the bottom grid, superficial gas velocity and average particle size and/or particle densities of the mixture through the dimensional analysis. Correlation on the basis of Artificial Neural Network approach has also been developed with the above system parameters thereby authenticating the development of correlation by the former approach. The calculated values of the segregation distance obtained for both the homogeneous and heterogeneous binary mixtures from both the types of ftuidized beds （i.e. under the static bed condition and the ftuidized bed condition） have also been compared with each other.

关键词： gas-solid fluidization Segregation distance Static bed condition Fluidized bed condition Irregular binaries and artificial neural network

The Game Theoretical Approach for Multi-phase Complex Systems in Chemical Engineering

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Journal of Systems Science & Complexity 2017年第1期30卷 4-19页

作者： LI Yan MU Yifen YUAN Shuo GUO Lei Beijing National Day School Beijing 100039 China Key Lab of Systems and Control Institute of Systems Science Academy of Mathematics and Systems ScienceChinese Academy of Sciences Beijing 100190 China

This paper explores the application of noncooperative game theory together with the concept of Nash equilibrium to the investigation of some basic problems on multi-scale structure, especially the meso-scale structure in the multi-phase complex systems in chemical engineering. The basis of this work is the energy-minimization-multi-scale （EMMS） model proposed by Li and Kwauk （1994） and Li, et al. （2013） which identifies the multi-scale structure as a result of ＇compromise-in-competition between dominant mechanisms＇ and tries to solve a multi-objective optimization problem. However, the existing methods often integrate it into a problem of single objective optimization, which does not clearly reflect the ＇compromise-in-competition＇ mechanism and causes heavy computation burden as well as uncertainty in choosing suitable weighting factors. This paper will formulate the compromise in competition mechanism in EMMS model as a noncooperative game with constraints, and will describe the desired stable system state as a generalized Nash equilibrium. Then the authors will investigate the game theoretical approach for two typical systems in chemical engineering, the gas-solid fluidiza- tion （GSF） system and turbulent flow in pipe. Two different cases for generalized Nash equilibrinm in such systems will be well defined and distinguished. The generalize Nash equilibrium will be solved accurately for the GSF system and a feasible method will be given for turbulent flow in pipe. These results coincide with the existing computational results and show the feasibility of this approach, which overcomes the disadvantages of the existing methods and provides deep insight into the mechanisms of multi-scale structure in the multi-phase complex systems in chemical engineering.

关键词： Game theory gas-solid fluidization generalized Nash equilibrium multi-phase complexsystems turbulent flow.

Prediction of Core-Annulus solids Mass Transfer Coefficient in gas-solid Fluidized Bed Risers

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Chinese Journal of Chemical Engineering 2005年第5期13卷 577-582页

作者：刘新华高士秋宋文立 Institute of Process Engineering Chinese Academy of Sciences

Based on analysis of energy dissipation in the core region of gas-solid fluidized bed risers, a simplified model for determination of core-annulus solids mass transfer coefficient was developed according to turbulent diffusion mechanism of particles. The simulation results are consistent with published experimental data. Core-annulus solids mass transfer coefficient decreases with increasing particle size, particle density and solids circulation rate,but generally increases with increasing superficial gas velocity and riser diameter. In the upper dilute region of gas-solid fluidized bed risers, core-annulus solids mass transfer coefficient was found to change little with the axial coordinate in the bed.

关键词： solids mass transfer coefficient core-annulus structure turbulent diffusion gas-solid fluidization