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Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Particles’ simplified motion equations were solved using the fourth order Runge-Kutta algorithm and their settling velocities as well as displacements along with time in liquid-solid fluidized bed separator were obtained. Fluidization experiment system was set up to verify the correctness of the calculated values of hindered settling velocities from solving particles’ simplified motion equations. The relative error of calculated hindered terminal settling velocities could be kept within 5% overall compared with the experimental values. Then, a mathematical model for liquid-solid fluidized bed separator was proposed based on particles’ simplified motion equations. The predicted partition values of different density fractions were validated with separation experiment, demonstrating that the mathematical model used in this work could give a well enough predicted separation result with a root-mean-square error of 5.05 of all density fractions. Using the mathematical model, the influence of feed rate on the separation results was explored, indicating the decreasing of the ratio of fluidized bed effective density ρeffto δ50(separation density) was the reason that separation efficiency decreased with the feed rate increasing. [ABSTRACT FROM AUTHOR]

It is difficult to simulate the pulsing airflow separation process of fine coal accurately using the conventional numerical model，such as Eulerian Model and Discrete Phase Model. The Dense Discrete Phase Model (DDPM) of the pulsing airflow separation process of fine coal was proposed based on the volume fraction of discrete phase and Soft-sphere approach to account for the influence from the volume of particles and the forces that result from the collision of particles. The distribution of the flow field and the separation results of 6-3 mm coal particles in pulsing air classifier were simulated through numerical simulation and continuous separation experiments in laboratory. The results show that DDPM was suitable for the simulation of the pulsing airflow separation process of fine coal and it was effective to show the perturbation action on the distribution of the flow field from particle phases. The separated materials had a significant impact on the distribution of the flow field，particularly on the velocity distribution and the change of pressure drop. Moreover，the greater handling capacity of the pulsing air classifier，the more significantly change of pressure drop. Within the scope of experiment conditions，the root-mean-square error of partition coefficients of heavy product in different density fractions was less than 3% by the method of DDPM，and the greater handling capacity，the higher separation density when the blowing rate was constant. [ABSTRACT FROM AUTHOR]

The gas-liquid flow fields of Liquid Solid Fluidized Bed Separator (LSFBS) were simulated using VOF (Volume of Faction) multiphase model with the RNG k-ε Model as a turbulence closure model. After the relatively stable two-phase flow fields were reached，the separation processes in the LSFBS of multi-solid particles with different sizes and densities were simulated using the Lagrangian Discrete Phase Model (DPM). The simulation results match well with the experimental results.The root-mean-square error (RMSE) between the predicted separation results and the experimental values is 2.47 while the relative error of predicted clean coal yield is 2.38%. The distribution of LSFBS's velocity fields was discussed.The impacts on the separation performance of the upward currents' flow rate as well as the pulsating upward currents' cycles and waveforms were explored. The mathematical relationships between separation density and upward current rate，Ep value and upward current rate were set up. According to the simulation results，the separation performances of steady upward currents are better than those of pulsating upward currents.For pulsating upward currents，the optimal cycle is 1.25 s while the best waveform is rectangular. [ABSTRACT FROM AUTHOR]

The theoretical and numerical simulation research on dense medium separation involves the rheological properties of suspensions. The apparent viscosities in different conditions of dense-medium suspension were determined to study the influence of density，volumetric concentration and coal slim e content on the rheological properties of medium suspension used in coal preparation. Linear fitting method was used to reduce the effect of particles sedimentation when measuring the apparent viscosity by the rotational viscometer on the range of density 1. 45 -1. 80 g/cm3 and coal slime content 0 — 0. 30. The experiment results show that the dense medium suspension used in coal preparation is pseudoplastic fluid. When the volumetric concentration is constant，consistency coefficient decreases approximately linearly , and power law exponent increases with the increment of coal slim e content. Under the condition of constant coal slime content，consistency coefficient increases approximately linearly，and power law exponent decreases with the volumetric concentration increasing. The equations for calculating consistency coefficient and power law exponent were put forward under the general conditions in industrial application of dense medium coal preparation respectively，and the relative deviation of the approximate formulas is less than ±10%. [ABSTRACT FROM AUTHOR]

The separation efficiency of an air-dense medium fluidized bed is directly affected by coal feed characteristics. So a systematic study had been carried out to investigate the effect of feed-coal particle size and different wash-ability on its separation characteristics. Moreover, the synergy between projectile strength, air volume and different coal feed characteristics on the separation characteristics was evaluated. The results show that the influence of feed-coal particle size on the separation accuracy is rather prominent. Ep values increase with the decrement of particle sizes. The minimum Ep values for 50-25, 25-13 and 13-6 mm difficult-separation coals are 0. 06,0. 07 and 0. 11 g/cm3, respectively. Washability has a slight effect on Ep. The minimum Ep values for easy-separation coal, moderate-separation coal and more difficult-separation coal of 50-25 mm size ranges are 0. 035, 0. 040 and 0. 045 g/cm3, respectively. Separation accuracy is dramatically improved by the optimization of air volume and projectile strength. The optimum operating process parameters of different coal feed characteristics range over which the separator can operate satisfactorily, are found that projectile strength and air volume are 1. 46 and 140 m3/h, respectively. The mechanism of improving fluidized separation by vibration was revealed by analyzing the relationships between initial bubbles frequency and vibration frequency in the vibrated air-dense medium fluidized bed. [ABSTRACT FROM AUTHOR]