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Apparent viscosity of mixed particle system in pulsed gas-solid separation fluidized bed

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Particuology 2022年第12期71卷 41-46页

作者： Zhonglin Gao Chenlong Duan yuemin zhao Pengfei Mao Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education School of Chemical Engineering and TechnologyChina University of Mining and TechnologyXuzhou 221116China

The apparent viscosity reflects the resistance of the fluidized medium in the bed to the beneficiation particles,which directly affects the separation time and mismatch ***,the falling-ball method was used to measure the apparent viscosity of a binary medium in a pulsed fluidized bed by varying the gas velocity,pulsation frequency,and fine particle *** results show that with increasing gas velocity and fine particle content,the apparent viscosity of the bed gradually decreased,whereas it first decreased and then increased with pulsation frequency increasing and achieved a minimum value in the range of 4-6 *** limits,the adjustment of gas velocity and fine content can effectively reduce the apparent viscosity and improve the separation process.A model for predicting the apparent viscosity in a pulsation separation fluidized bed was established with good accuracy.

关键词： Pulsed fluidized bed Mixed medium Apparent viscosity Drag coefficient

Effect of coal particle swarm properties on the fluidization characteristics and coal beneficiation in a dense-phase gas-solid fluidized bed

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Particuology 2017年第6期15卷 108-118页

作者： Bo Zhang Chenyang Zhou Zengqiang Chen yuemin zhao Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education China University of Mining & Technology Xuzhou 221116 China School of Chemical Engineering and Technology China University of Mining & Technology Xuzhou 221116 China

This paper analyzes the influence of different coal mass fraction in an air dense medium fluidized bed （ADMFB）. The effect of the low density particles layer on heavy sedimentation increased with increasing material layer thickness. The thickness of the low density particles layer also affected the final settling time of the high densiW particles. Increasing the thickness of the low density particles layer by △h provoked an increase in the settling of high density particles that was related to their diameter （△h/D）. The pressure gradient across the bed was lower than that observed for the control experiment, which had only the dense material, owing to a decrease in the pressure gradient in Zones 1 and 5 （at the top and bottom of the bed, respectively）. Introducing different coal sizes resulted in different fluidization environments, particle accumulation layers, and changes to the surrounding zone. However, the influence of the coal particles on the local bed characteristics was related to its concentration. The feeding mass fraction of 6-13mm size and 13-25mm size coal should be limited to10% and 13%, respectively. The ranges of possible deviation were found to be 0.08-0.15 and 0.07-0.10 for the respective samples.

关键词： Coal separation Particle size distribution Fluidized bed Separation performance

A method to improve fluidization quality in gas-solid fluidized bed for fine coal beneficiation

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Particuology 2019年第2期17卷 181-192页

作者： Chenyang Zhou Xuchen Fan Chenlong Duan yuemin zhao Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education School of Chemical Engineering and Technology China University of Mining and Technology Xuzhou 221116 China

Dry coal separation has become essential in China because it does not consume water and it reduces environmental pollution. In this study, a method for improving fluidization quality in a fluidized bed separator using a micropore sponge is proposed. The separator is used for fine coal beneficiation. The pressure drop across the distributor and bed fluidization characteristics were analyzed to evaluate fluidization quality. The beneficiation efficiency for fine coal was further investigated by using a laboratory-scale fluidized bed with and without a micropore sponge. With the sponge, the highest pressure drop fluctuation factor decreased from 0.23 to 0.16, indicating an improvement in density stability. The modified separation method reduced the ash content of a sample of fine coal from 23.83% to 10.70%. The probable error efficiency value E for -6 + 3 mm coal was 0.12g/cm^3, close to the efficiency error values reported for other dry-beneficiation techniques. The separation results show that using a sponge in the fluidized bed can readily improve the efficiency of fine coal beneficiation.

关键词： Fluidized bed Coal beneficiation Micropore sponge Fine coal Dry separation Distributor

Segregation modes,characteristics,and mechanisms of multi-component lignite in a vibrated gas-fluidized bed

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International Journal of Mining Science and Technology 2018年第2期28卷 251-258页

作者： Su Ding Luo Zhenfu Lei Lingyan zhao yuemin School of Chemical Engineering&Technology China University of Mining&TechnologyXuzhou 221116China Xuzhou Coal Mining Group Xuzhou 221006China School of Environmental Science and Spatial Informatics China University of Mining&TechnologyXuzhou 221116China

The segregation modes and characteristics of 1-6 mm multi-component lignite were studied in a microporous, vibrated, gas-fluidized bed of Φ110 mm ×400 mm. The effects of particle density and size, vibration frequency and amplitude, and gas velocity on these characteristics were considered. The average size, average density, size deviation coefficient, and density deviation coefficient were used to identify lignite size and density. The separation efficiency was adopted to evaluate the segregation performance,and the segregation mechanisms were explored. The results show that ε(size,max) of heterogeneous multisize-component lignite with K_(size) = 65% reaches 80% at f= 20 Hz, A = 5 mm, and N =(1,3). ε_(density,max) Of heterogeneous multi-density-component lignite with K_(density)= 25% reaches 50% at f = 15 Hz, A = 5 mm,and N =(1,1.5). The density segregations of 1-3 and 3-6 mm multi-component mixtures are remarkable,ε_(density,max)= 42% and 31% at f= 14 and 16 Hz, and A = 3 and 5 mm, respectively. The size segregation of 1-6 mm multi-component mixture is prominent and ε_(size,max)= 55% at f= 15 Hz, A = 5 mm. The mediumsized mixture with a narrow size distribution at low frequency is favorable for density segregation,and a mixture with a wider size distribution at high frequency is most favorable for size *** control of gas flow and vibration as well as optimal design of the fluidized bed can improve the performance of segregation in the vibrated gas-fluidized bed.

关键词： Dry-beneficiation Multi-component lignite Segregation mode Degree of homogeneity

Separation performance of fine low-rank coal by vibrated gas-solid fluidized bed for dry coal beneficiation

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Particuology 2015年第6期13卷 100-108页

作者： Jingfeng He yuemin zhao Jie zhao Zhenfu Luo Chenlong Duan Yaqun He School of Chemical Engineering and Technology Chino University of Mining and Technology Xuzhou 221116 China

Vibrational energy was introduced to a dense medium gas-solid fluidized bed to improve the separation performance of 1-6 mm fine low-rank coal. The setup was termed a vibrated gas-solid fluidized bed and could provide a stable fluidization state and uniform density distribution for dry coal beneficiation by the transfer of vibrational energy and the interaction between vibrations and the gas phase. Favorable segregation of the ash content of the 1-6-ram-sized lignite samples is achieved under suitable operating conditions. Higher yields of cleaning coal were acquired when the ash content was reduced. The probable error values were 0.065 and 0.055 at separating densities of 1.68 and 1.75 g/clTl3 for the 1-3- and 3-6-mm- sized lignite samples, respectively. Effective beneficiation of 1-6-ram-sized fine lignite could be achieved using the vibrated gas-solid fluidized bed, which provides an alternative technique for the separation of fine low-rank coal in arid areas.

关键词： Lignite Vibrational energyGas-solid fluidized bedSegregationSeparation performance

Analysis and evaluation on pressure fluctuations in air dense medium fluidized bed

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International Journal of Mining Science and Technology 2018年第3期28卷 461-467页

作者： Sheng Cheng Duan Chenlong zhao yuemin Dong Liang Luo Zhenfu Key Laboratory of Coal Processing and Efficient Utilization of Ministry of Education School of Chemical Engineering & Technology China University of Mining & Technology Xuzhou 221116 China Forschungszentrum Jülich Julich 52428 Germany

Pressure fluctuations contribute to the instability of separation process in air dense medium fluidized bed, which provides a high motivation for further study of underlying mechanisms. Reasons for generation and propagation of pressure fluctuations in the air dense medium fluidized bed have been *** rate and collision rate of particles were employed to deduce the correlation between voidage and pressure fluctuations. Simultaneously, a dynamic pressure fluctuation measuring and analysis system was established. Based on frequency domain analysis and wavelet analysis, collected signals were disassembled and analyzed. Results show gradually intensive motion of particles increases magnitudes of signal components with lower frequencies. As a result of violent particle motion, the magnitude of real pressure signal's frequency experienced an increase as air velocity increased moderately. Wavelet analysis keeps edge features of the real signal and eliminates the noise efficaciously. The frequency of denoised signal is closed to that of pressure signal identified in frequency domain analysis.

关键词： Air dense medium fluidized bed Pressure fluctuations Frequency domain analysis Wavelet analysis Particle distribution function

Density distribution in a heavy-medium cyclone

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Mining Science and Technology 2011年第2期21卷 175-179页

作者： Wang Yuling zhao yuemin Yang Jianguo School of Chemical Engineering and Technology China University of Mining ＆ Technology Xuzhou 221008 China

Heavy-medium cyclones are widely used to upgrade run-of-mine *** the understanding of flow in a cyclone containing a dense medium is still *** introducing turbulent diffusion into calculations of centrifugal settling a theoretical distribution function giving the density field can be *** analysis of the density field in every part of a cylindrical cyclone suggests an optimum design that has exhibited good separation effectiveness and anti-wear performance when in commercial operation.

关键词： Heavy-medium cyclone Density field Density flow model Optimization

Influence of vibration mode on the screening process

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International Journal of Mining Science and Technology 2013年第1期23卷 95-98页

作者： Dong Hailin Liu Chusheng zhao yuemin zhao Lala School of Mechanical and Electrical Engineering China University of Mining & Technology Key Laboratory of Coal Processing and High Efficient Cleaning and Utilization of Ministry of Education School of Chemical Engineering and Technology China University of Mining & Technology

The screening of particles with different vibration modes was simulated by means of a 3D discrete element method (3D-DEM). The motion and penetration of the particles on the screen deck were analyzed for linear, circular and elliptical vibration of the screen. The results show that the travel velocity of the particles is the fastest, but the screening efficiency is the lowest, for the linear vibration mode. The circular motion resulted in the highest screening efficiency, but the lowest particle travel velocity. In the steady state the screening efficiency for each mode is seen to increase gradually along the longitudinal direction of the deck. The screening efficiency increment of the circular mode is the largest while the linear mode shows the smallest increment. The volume fraction of near-mesh size particles at the underside is larger than that of small size particles all along the screen deck. Linear screening mode has more near-mesh and small size particles on the first three deck sections, and fewer on the last two sections, compared to the circular or elliptical modes.

关键词： Vibration mode Screening process Particles Discrete element method

Characteristics of pressure fluctuations and fine coal preparation in gas-vibro fluidized bed

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Particuology 2015年第4期13卷 146-153页

作者： Liang Dong yuemin zhao Liping Peng Jie zhao Zhenfu Luo Qingxia Liu Chenlong Duan School of Chemical Engineering and Technology China University of Mining and Technology School of Mechatronic Engineering China University of Mining and Technology Department of Chemical and Materials Engineering University of Alberta

To improve the separation efficiency of air dense medium fluidized beds tor dry coal preparation, a gasvibro fluidized bed has been proposed in which magnetic powder is used as the heavy medium. Pressure fluctuations in the gas-vibro fluidized bed were investigated using time- and frequency-domain analysis methods. The relationship between pressure fluctuations, bubble behavior, and separation efficiency was established. The low amplitude of the standard deviation, the power spectral density （PSD）, the incoherent-output PSD, and the high amplitude of the coherent-output PSD, which corresponds to the bubble behavior in the bed, were improved for coal preparation. The coal ash content was reduced from 42.5570 to 16.54% by using the gas-vibro fluidized bed.

关键词： Pressure fluctuation Gas-vibro fluidized bed Power spectral Coherence Coal preparation