Investigation of the segregation of a binary particle mixture in a square circulating fluidized bed with air staging
Publication date: Available online 4 September 2019Source: ParticuologyAuthor(s): Mingkun Du, Shuai WangAbstractTo further understand the segregation characteristics of a binary particle mixture in a riser, the flow behaviors of particles with different sizes were experimentally and numerically investigated in a cold square circulating fluidized bed. The impact of the gas velocity, solid circulation rate, initial coarse particle fraction, and air staging on the coarse particle fraction and axial pressure drop were examined. The experimental results show that air staging can significantly promote the pressure drop of a bina...
Source: Particuology - September 5, 2019 Category: Science Source Type: research
Particle mixing behavior of fine coal in density control of gas–solid separation fluidized bed
Publication date: Available online 4 September 2019Source: ParticuologyAuthor(s): Bo Lv, Zhenfu Luo, Yanhong Fu, Bo Zhang, Xingzong Qin, Xiangnan ZhuAbstractIn a gas–solid separation fluidized bed, mixing of fine coal is necessary to achieve a suitable bed density to enable effective separation of low rank coal. On the basis of a variety of mixture models, a gas–solid separation fluidized bed was judged, where fine coal particles of 0.6–1.0 mm were uniformly mixed with magnetite powder. High-speed dynamic camera technology was combined with a slump-sampling method to study the mixing process of the fine coal in ...
Source: Particuology - September 4, 2019 Category: Science Source Type: research
Development of a rapid measurement system for coarse aggregate morphological parameters
Publication date: Available online 13 August 2019Source: ParticuologyAuthor(s): Hejun Zhu, Huaiying Fang, Yuanyuan Cai, Ning LvAbstractMorphological parameters of coarse aggregates, including the angularity index (AI), flat and elongated ratio, flatness ratio, and sphericity, strongly affect the performance of asphalt concrete. A device must be developed to efficiently and accurately measure these parameters. Herein, a charge-coupled device camera and a linear profile scanner are combined to evaluate the parameters. The AI is calculated using three methods. The results show that the fitted-ellipse method provides superior ...
Source: Particuology - August 14, 2019 Category: Science Source Type: research
Coating particles using liquids and foams based on viscous formulations with industrial mixers: Batch operation
In this study, two shear mixers are used; the first type consists of paddles in different configurations attached to a single rotating shaft, whilst the second type is a commercial twin screw mixer (TSM). The quality of coating achieved on the bulk powder bed using liquids and foams (stained with a dye) is assessed by image analysis to determine the homogeneity of the color distribution. In addition, scanning electron microscopy provides a tool to further investigate the coating quality of individual particles from the bulk product.The results show that large bubble (centimeter size) foams are much more effective at distri...
Source: Particuology - August 9, 2019 Category: Science Source Type: research
Editorial Board
Publication date: October 2019Source: Particuology, Volume 46Author(s): (Source: Particuology)
Source: Particuology - August 9, 2019 Category: Science Source Type: research
A comparison of centrifugation and tangential flow filtration for nanoparticle purification: A case study on acetalated dextran nanoparticles
Publication date: Available online 5 August 2019Source: ParticuologyAuthor(s): Nishan K. Shah, Ryan Ivone, Jie Shen, Samantha A. MeenachAbstractTangential flow filtration (TFF) is a purification method commonly used in a multitude of fields, including particle engineering. Currently, there is still a lack of comprehensive understanding of the effects of key TFF parameters on nanoparticle (NP) characteristics (purification outcomes). The present study aimed to investigate the influence of various factors on the characteristics of TFF-purified NP. The most commonly used NP purification method, centrifugation, was studied as ...
Source: Particuology - August 6, 2019 Category: Science Source Type: research
Two-fluid modelling for cylindrical fluidized beds using kinetic theory for rough spheres
In this study, the extended KTGF implemented in cylindrical coordinates is used to model the more-commonly employed cylindrical bubbling fluidized beds. Special attention is paid to the anti-symmetric part of the velocity gradient in the solids stress tensor. For verification of the implementation, a comparison of the present model in the limit of zero friction with the original (frictionless) KTGF model was made. Subsequently, simulations of bubbling fluidized beds of inelastic particles were performed using our extended KTGF and an effective KTGF model for inelastic particles of Jenkins and Zhang. The simulation results ...
Source: Particuology - August 6, 2019 Category: Science Source Type: research
Synthesis of mesoporous silica microspheres by a spray-assisted carbonation microreaction method
Publication date: Available online 5 August 2019Source: ParticuologyAuthor(s): Chunli Han, Yunpeng Hu, Kai Wang, Guangsheng LuoAbstractA novel spray-assisted carbonation microreaction method for the synthesis of mesoporous silica microspheres is reported. The synthetic process comprises the preparation of a silica sol via a carbonation reaction, rapid gelation at high temperature, and subsequent rapid solvent evaporation by spray drying. The carbonation microreaction was conducted in a membrane dispersion microreactor, in the presence of sodium silicate and carbon dioxide reactants. The as-synthesized silica microspheres e...
Source: Particuology - August 6, 2019 Category: Science Source Type: research
Prediction of particle size and layer-thickness distributions in a continuous horizontal fluidized-bed coating process
Publication date: Available online 6 August 2019Source: ParticuologyAuthor(s): P. Bachmann, K. Chen, A. Bück, E. TsotsasAbstractTo predict the particle size and layer-thickness distributions (LTDs) in a continuously operated horizontal fluidized-bed granulation process, two alternative models were considered. A one-dimensional two-zone model was proposed, which describes with population-balance equations the particle growth in a spraying zone that is separated from the drying zone. The residence-time distribution (RTD) was calculated from a literature correlation and was coupled with a population-balance model via a tank-...
Source: Particuology - August 6, 2019 Category: Science Source Type: research
Study of the wall adhesive tensile contact of moist iron ore bulk solids
In this study, an experimental system was designed to investigate the adhesive tensile contact between a range of iron ore materials and wall lining specimens. The contact mechanism between the material specimen and the wall surface was initially characterised. The experimental results indicated that the adhesive tensile stress is dependent on both the moisture content and the applied major consolidation stress, with the former exhibiting more significant contribution to increasing the magnitude of stress. The surface roughness of the wall showed a negligible effect in determining the adhesive tensile stress. Additionally,...
Source: Particuology - August 4, 2019 Category: Science Source Type: research
NURBS-based DEM for non-spherical particles
In this study, we use non-uniform rational basis-splines (NURBS) to describe the shapes of non-spherical particles and introduce a contact detection scheme based on quadratic convergence, to simulate the behaviors of elliptical particles. The simulation results are compared with those based on polygons, in terms of the shape description and contact treatment, to demonstrate the high accuracy and efficiency of NURBS-based DEM.Graphical abstract (Source: Particuology)
Source: Particuology - July 30, 2019 Category: Science Source Type: research
Synthesis of size-controlled hollow Fe3O4 nanospheres and their growth mechanism
Publication date: Available online 23 July 2019Source: ParticuologyAuthor(s): Lei Shi, Yurong He, Yanwei Hu, Xinzhi Wang, Baocheng Jiang, Yimin HuangAbstractSize-controlled hollow Fe3O4 nanospheres were synthesized via a one-pot hydrothermal method as a function of reaction time and sodium citrate, polyacrylamide, and urea content. Multiple characterization techniques such as scanning and transmission electron microscopy and Raman spectroscopy were employed to investigate the crystal structure and morphology of the obtained nanospheres. The Fe3O4 nanosphere formation mechanism was elucidated from analyzing the characteriza...
Source: Particuology - July 23, 2019 Category: Science Source Type: research
DEM investigation of angle of repose for super-ellipsoidal particles
Publication date: Available online 17 July 2019Source: ParticuologyAuthor(s): Hao Chen, Shiwei Zhao, Xiaowen ZhouAbstractWe explore the effect of particle shape on the angle of repose (AoR) in granular packing using a three-dimensional discrete element method. Non-spherical particles were modeled using super-ellipsoids characterized by aspect ratio and blockiness. The relationship between AoR and particle shape was examined, followed by a series of analyses on the origin of AoR from a microscopic perspective. Results show that, with blockiness deviating from unity, AoR has an approximate “M” shape that exhibits a stron...
Source: Particuology - July 18, 2019 Category: Science Source Type: research
Effects of riser geometry on gas–solid flow characteristics in circulating fluidized beds
In this study, a laboratory-scale circulating fluidized bed with three different riser geometries (circular, square, and rectangular) that had the same cross-sectional area and height was operated under two static bed heights (20, and 35 cm). Electrical capacitance tomography was combined with differential pressure transducers and an optical-fiber probe to measure the solids’ volume fraction, differential pressure fluctuations, and radial particle concentration variations. Computational particle fluid dynamics simulations were also performed. The results showed that single bubbles appeared in the bottom region of th...
Source: Particuology - July 18, 2019 Category: Science Source Type: research
A fluidized-bed model for NiMgW-catalyzed CO2 methanation
This study examines how the operating parameters affect CO2 methanation in a highly efficient fluidized-bed reactor. We first measured the kinetics of the CO2 methanation reaction using an NiMgW catalyst, which has been reported to exhibit superior catalytic performance. We then developed a fluidized-bed reactor model based on an earlier model for CO2 methanation. The fluidized bed model indicated that the NiMgW was indeed superior to two other previously studied catalysts in terms of faster conversion of reactants and higher concentrations of product CH4 throughout the reactor. The overall rate of production of CH4 increa...
Source: Particuology - July 18, 2019 Category: Science Source Type: research
