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Low-velocity pneumatic conveying in horizontal pipe for coarse particles and fine powders

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Particuology 2008年第5期6卷 316-321页

作者： Yuji Tomita Vijay Kumar Agarwal Hiroyuki Asou Katsuya Funatsu Kyushu Institute of Technology 1-1 SensuichoTobataKitakyushu 804-5500Japan Indian Institute of Technology Hauz KhasNew Delhi 110016India

First, the characteristics of low-velocity conveying of particles having different hardness are experimentally investigated in a horizontal pipeline in terms of flow pattern and pressure drop to show that the slug flow can be classified into two types depending on the settling of particles along the pipeline, and the period is small for slug flow without the settled layer, which is called solitary slug flow. The pressure drop for soft particles is shown to be larger than that for hard particles. Then, experimental results are presented on horizontal fluidized-bed conveying of fine powders to show that air release from the top surface of the conveying channel is an imnortant factor for high mass flow rate of particles.

关键词： Low-velocity conveying Slug flow Soft particle Horizontal fluidized-bed conveying fine powder

FLUIDIZATION OF fine powderS IN FLUIDIZED BEDS WITH AN UPWARD OR A DOWNWARD AIR JET

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China Particuology 2005年第3期3卷 181-186页

作者： RuoyuHong JianminDing HongzhongLi DepartmentofChemistryandChemicalEngineering SoochowUniversitySuzhou215006P.Ft.China//Multi.PhaseReactionLaborato~ln~uteofPr~x~s.~Engineering.Chinese..AcadermyofSconcesBeijing100080P.R.China IBM HYDN050-3C2023605Highway52NorthRochesterMN55901USA Multi-PhaseReactionLaboratory InstituteofProcessEngineeringChineseAcademyofSciencesBeijing100080P.R.China

The hydrodynamic behavior of fine powders in jet-fluidized beds was studiednumerically and experimentally. The starting point of numerical simulation was the generalizedNavier-Stokes (N-S) equations for the gas and solids phases. The κ-ε turbulence model was used forhigh-speed gas jets in fluidized beds. Computation shows that a suitable turbulence model isnecessary to obtain agreement between the simulation and literature experimental data for ahigh-speed gas jet. The model was applied to simulating the fluidization of fine powders influidized beds with an upward or a downward air jet. An empirical cohesion model was obtained bycorrelating the cohesive force between fine particles using a cohetester. The cohesion model wasembedded into the two-fluid model to simulate the fluidization of fine powders in two-dimensional(2-D) beds. To study the fluidization behavior of fine and cohesive powders with a downward jet,experiments were performed in a 2-D bed. Agreement between the computed time-averaged porosity andmeasured data was obtained. With an upward jet in the bed center, the measured and computedporosities show a dilute central core, especially at very high jet velocities. Based on ourexperiments and computations, a downward jet located inside the bed is recommended to achieve bettermixing and contacting of gas and solids.

关键词： fluidization jet fine powder two-fluid model

Experimental investigation on micro-dynamic behavior of gas explosion suppression with SiO_2 fine powders

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Theoretical & Applied Mechanics Letters 2011年第3期1卷 58-61页

作者： Xianfeng Chen,~(1,2,a)) Yin Zhang,~1 Qingming Zhang,~2 Shaofeng Ren,~1 and Jianxing Wu~1 1)School of Natural Resources and Environmental Engineering,Wuhan University of Technology, Wuhan 430070,China 2)State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology, Beijing 100081,China State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China

To study the effect of inert dust on gas explosion suppression mechanism,SiO_2 fine powders were sprayed to suppress premixed CH_4-Air gas explosion in a 20 L spherical experimental *** the experiment,high speed schlieren image system was adopted to record explosion flame propagation behaviors,meanwhile,pressure transducers and ion current probes were used to clearly record the explosion flame dynamic *** experimental results show that the SiO_2 fine powders suppressed evidently the gas explosion flame,and reduced the peak value of pressure and flame speed by more than 40%.The ion current result shows that the SiO_2 super fine powders were easy to contact with and absorb free radicals near the combustion reaction region,which greatly reduced the combustion reaction intensity,and in turn influenced the flame propagation and pressure rising.

关键词： fine powder gas explosion explosion suppression reaction mechanism

Reduction of 1-3 mm iron ore by H_2 in a fluidized bed

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International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 620-625页

作者： Jian-ming Pang Pei-min Guo Pei Zhao Chao-zhen Cao Ding-guo Zhao Duo-gang Wang The State Key Laboratory for Advanced Steel Processes and Materials Central Iron and Steel Research Institute Beijing 100081 China

The reduction of 1-3 mm fine powder of iron ore by H2 was conducted in a lab-fabricated kg class high temperature fluidized bed. The results show that the differential pressure in the fluidized bed, which has small fluctuation with time, increases with the increase of gas flowing velocity. The utilization ratio of gas decreases when the reaction lasts longer time indicating that the reaction is faster at the beginning of reduction and becomes slower in the latter process. The higher the reaction temperature is, the higher the utilization ratio of gas is, but the difference of utilization ratio among the different temperatures becomes smaller with time. The utilization ratio of gas and the metallization ratio can reach 9% and 84% respectively at 750℃ for 20 min, which shows the reduction reaction by H2 is very fast. The increase of metallization ratio with gas velocity performs quite good linearity, which shows that a higher velocity of reducing gas can be used to improve the productivity of the reactor when H2 is used as reducing gas. With the increase of charge height, the metallization ratio decreases, but the utilization ratio of gas increases. The reaction temperature can be reduced to 700-750℃ from 800-850℃ when H2 is used as reducing gas.

关键词： hydrogen fluidized bed fine powder iron ore ironmaking reduction reaction

Reduction of 1-3 mm Iron Ore by CO on Fluidized Bed

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Journal of Iron and Steel Research International 2011年第3期18卷 1-5页

作者： PANG Jian-ming GUO Pei-min ZHAO Pei The State Key Laboratory for Advanced Steel Processes and Products Central Iron and Steel Research InstituteBeijing 100081China

The reduction-degree of the sample increases and the utilization ratio of gas decreases when the reaction lasts longer time,which indicates that the reaction is faster at the beginning of reduction,while it becomes slower in subsequent *** higher the reaction temperature,the higher the utilization ratio of gas and the reduction-degree are,but the difference of utilization ratio among the different temperatures becomes smaller with *** utilization ratio of gas can reach about 8% and the reduction-degree is 80% for 20 min reduction at 850 ℃,indicating that the reduction reaction by CO is very fast at high *** higher the reaction temperature,the higher the apparent reaction rate constant is,but the difference of apparent reaction rate constant among the different temperatures becomes *** apparent activation energy is about 59.11 kJ/mol in the fluidized bed *** increase of reduction-degree with gas velocity shows quite good linearity,indicating that at high temperature even higher velocity of reducing gas can be used to improve the productivity of reactor when CO is used as reducing *** the increase of charge height,the metallization ratio and the reduction-degree decrease,but the utilization ratio of gas increases.

关键词： CO fluidized bed fine powder iron ore reduction-degree

The Influence of an Acoustic Field on the Bed Expansion of fine Particles

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Chinese Journal of Chemical Engineering 2011年第4期19卷 649-655页

作者： Akash M. Langde R.L.Sonolikar Anjuman College of Engineering and Technology Nagpur Maharashtra India Laxminarayan Institute of Technology Nagpur Maharashtra India

fine particles are difficult to fluidize due to strong interparticle *** attempt has been made to study the bed expansion of silica gel(dp=25μm) powder in presence of an acoustic field.A 135 mm diameter fluidized bed activated by an acoustic field with sound intensity up to 145 dB and frequency from 90 Hz to 170 Hz was *** effects of sound pressure level,sound frequency and particle loading on the bed expansion were *** results showed that,bed expansion was good in presence of acoustic field of particular *** addition,it was observed that in presence of acoustic field the bed collapses slowly.

关键词： acoustic field frequency vibration fluidized bed fine powder expansion