Powder Technology最新文献

英文中文

Methane dry reforming in a microwave heating-assisted dense fluidized bed 在微波加热辅助密集流化床中进行甲烷干重整

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-13 DOI: 10.1016/j.powtec.2024.120444

Mojtaba Mokhtari, Jaber Shabanian, Jamal Chaouki

Dry reforming of methane helps mitigate greenhouse gas emissions as a global issue. This technology produces syngas, which can be converted into valuable chemicals, e.g., synthetic fuels. Electrification of this technology by adopting a microwave heating-assisted dense fluidized bed dry reformer can enhance its sustainability. In the present study, we developed a model to assess the performance of this reactor. This first-of-its-kind model employed an Eulerian-Granular multiphase model in conjunction with Maxwell's equation to simulate catalyst particles' hydrodynamics and microwave-induced heating while combined with the corresponding reactions to predict the overall performance of the dense fluidized bed reactor. We validated the model with experimental data from literature and performed a set of parametric studies with the validated model. This model holds promise for identifying the optimal operating conditions of the selected reformer, i.e., a crucial step toward commercialization of microwave heating-assisted dry reforming of methane.

甲烷干转化技术有助于缓解温室气体排放这一全球性问题。该技术产生的合成气可转化为有价值的化学品，如合成燃料。通过采用微波加热辅助密集流化床干转化器实现该技术的电气化可提高其可持续性。在本研究中，我们开发了一个模型来评估这种反应器的性能。该模型首次采用了欧拉-粒状多相模型，结合麦克斯韦方程模拟催化剂颗粒的流体力学和微波诱导的加热，同时结合相应的反应来预测密集流化床反应器的整体性能。我们用文献中的实验数据验证了该模型，并用验证后的模型进行了一系列参数研究。该模型有望确定所选转化炉的最佳运行条件，这也是实现微波加热辅助甲烷干法转化商业化的关键一步。

引用次数: 0

Effect of mechanical milling time on powder characteristic, microstructure, and mechanical properties of AA2024/B4C/GNPs hybrid nanocomposites 机械研磨时间对 AA2024/B4C/GNPs 混合纳米复合材料粉末特性、微观结构和力学性能的影响

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-13 DOI: 10.1016/j.powtec.2024.120439

Müslim Çelebi, Aykut Çanakçı, Serdar Özkaya

In this study, hybrid nanocomposites consisting of an AA2024 matrix reinforced with 1 wt% B₄C nanoparticles and 1 wt% GNPs were produced using a powder metallurgy method assisted by mechanical milling. This study aimed to systematically investigate the effect of grinding time on powder characteristics (particle size, microhardness, and morphology) as well as microstructure, densification, and mechanical performance to optimize processing conditions for superior material properties. Microstructural characterization of powders and bulk samples were carried out using a SEM device equipped with EDS. The results indicate that with increasing milling time, the particle size significantly decreased, while the particle hardness increased substantially. Additionally, the sample milled for 8 h achieved the highest relative density among the hybrid nanocomposites, reaching a value of 95.3 %. Mechanical tests revealed that after 8 h of milling, the hardness and tensile strength reached peak values of 164 HB and 314 MPa, corresponding to increases of 56 % in hardness and 43 % in tensile strength compared to the unreinforced alloy. The analysis results confirm that the optimal properties were obtained after 8 h under all conditions.

本研究采用机械研磨辅助粉末冶金方法制备了由 AA2024 基体与 1 wt% B4C 纳米粒子和 1 wt% GNPs 增强的混合纳米复合材料。本研究旨在系统研究研磨时间对粉末特性（粒度、显微硬度和形态）以及显微结构、致密化和机械性能的影响，以优化加工条件，获得优异的材料性能。使用配备 EDS 的扫描电镜设备对粉末和块状样品进行了微观结构表征。结果表明，随着碾磨时间的增加，颗粒尺寸明显减小，而颗粒硬度大幅增加。此外，在混合纳米复合材料中，碾磨 8 小时的样品相对密度最高，达到 95.3%。力学测试表明，碾磨 8 小时后，硬度和拉伸强度分别达到 164 HB 和 314 MPa 的峰值，与未增强合金相比，硬度和拉伸强度分别提高了 56% 和 43%。分析结果证实，在所有条件下，8 小时后都能获得最佳性能。

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引用次数: 0

Characterisation of a continuous blender: Impact of physical properties on mass holdup behaviour 连续式搅拌器的特性：物理特性对质量保持行为的影响

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-12 DOI: 10.1016/j.powtec.2024.120440

Hikaru Graeme Jolliffe , Maria A. Velazco-Roa , Luis Martin de Juan , Martin Prostredny , Carlota Mendez Torrecillas , Gavin Reynolds , Deborah McElhone , John Robertson

Continuous blenders are a key unit operation in Continuous Direct Compaction, a route to solid oral dosage forms that is receiving significant interest. Mass holdup in these blenders is a crucial variable; understanding how it is influenced by material properties, equipment configuration and process settings is key. The present work evaluated a Gericke GCM-450 blender for range of outlet weir aperture geometries (angled or horizontal), material properties (pure components and blends) and process settings (throughput and impeller speed). Results show opposing mass holdup behaviour depending on weir choice, material density and flowability, likely linked to the propensity of the material to form an inclined powder surface that matches – or does not – the chosen weir geometry. The present work underscores the need for fundamental process phenomena understanding, especially when insight is sought for how blender performance varies across multiple dimensions (throughput, impeller speed, material properties) and discrete equipment choices (weir geometry).

连续混料器是连续直接压制工艺中的一个关键单元操作，这种口服固体制剂的生产工艺正受到广泛关注。这些混料机中的容积是一个关键变量；了解材料特性、设备配置和工艺设置对容积的影响至关重要。本研究对 Gericke GCM-450 型混料机的出口堰孔几何形状（倾斜或水平）、材料特性（纯成分和混合物）和工艺设置（吞吐量和叶轮速度）进行了评估。结果表明，根据堰口的选择、材料密度和流动性的不同，保质行为也截然不同，这可能与材料倾向于形成与所选堰口几何形状相匹配或不匹配的倾斜粉末表面有关。本研究强调了了解基本工艺现象的必要性，尤其是在深入了解混料机性能如何在多个维度（产量、叶轮速度、材料特性）和离散设备选择（堰的几何形状）之间发生变化时。

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引用次数: 0

Mass discharge rate of granular flow in eccentric silos with variable side wall friction 具有可变侧壁摩擦力的偏心料仓中颗粒流的质量排出率

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-12 DOI: 10.1016/j.powtec.2024.120438

Ge Sun , Quan Chen , Ran Li , Tongtong Mu , Hui Yang

There are many studies on the effect of side wall friction on mass discharge rate (MDR), but the physical mechanism is lacking. In this paper, by changing side wall friction of eccentric silos, the relationship between macroscopic MDR and microscopic frictional coefficient was established, and the regulation of MDR up to a range of 40 % was realized. Furthermore, it is revealed that the variation of MDR is caused by the change in geometric structure of free-fall arch (FFA). In addition, the velocity of particles on FFA is the same under different MDR. The reason is that under high frictional coefficient, the gravitational potential energy of particles is more dissipated in the rotational motion caused by resistance. This work explains for the first time the mechanism of the frictional coefficient on MDR, and provides a data reference for improving the theoretical model of MDR.

关于侧壁摩擦对排料速率（MDR）影响的研究很多，但缺乏物理机制的研究。本文通过改变偏心筒仓的侧壁摩擦力，建立了宏观 MDR 与微观摩擦系数之间的关系，并实现了对 MDR 在 40% 范围内的调节。此外，研究还发现 MDR 的变化是由自由落体拱（FFA）几何结构的变化引起的。此外，在不同的 MDR 下，颗粒在 FFA 上的速度是相同的。这是因为在高摩擦系数条件下，颗粒的重力势能更多地耗散在由阻力引起的旋转运动中。该研究首次解释了摩擦系数对 MDR 的影响机理，为改进 MDR 理论模型提供了数据参考。

引用次数: 0

Simulating breakage by compression of iron ore pellets using the discrete breakage model 利用离散破碎模型模拟铁矿球团的压缩破碎

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-09 DOI: 10.1016/j.powtec.2024.120433

Horacio A. Petit , Alexander V. Potapov , Luís Marcelo Tavares

Simulation of breakage embedded in the discrete element method (DEM) has evolved significantly in recent years, taking advantage of both greater computing power and novel approaches that have become available in both commercial and open-source packages. This work analyzes in detail the simulation of breakage using the discrete breakage model (DBM) in the commercial software Ansys Rocky. Breakage of iron ore pellets under slow compression was studied. After the selection of suitable contact parameters for the pellets, described as polyhedral particles, the model is used to describe their breakage considering fully resolved fragments from the beginning of the simulation. The effects of contact model, time step and number of elements on the ability of the model to represent average breakage response of iron ore pellets under compression is analyzed. An approach was then used to account for the variability in the breakage characteristics of the pellets, which provided a valid description when applied to another pellet sample, also showing capability to describe the size-scale effect on the breakage energy of pellets when applied to pellets of different sizes.

近年来，离散元法 (DEM) 中嵌入的断裂模拟有了长足的发展，既利用了更强的计算能力，也利用了商业和开源软件包中可用的新方法。这项工作详细分析了使用商业软件 Ansys Rocky 中的离散破损模型 (DBM) 模拟破损的情况。研究了铁矿球团在缓慢压缩条件下的破损情况。在为被描述为多面体颗粒的球团选择合适的接触参数后，该模型用于描述球团的破碎，从模拟开始就考虑了完全解析的碎片。分析了接触模型、时间步长和元素数量对模型表示压缩下铁矿球团平均破碎响应能力的影响。然后使用一种方法来解释球团破裂特性的变化，这种方法在应用于另一种球团样本时提供了有效的描述，当应用于不同尺寸的球团时，也显示出描述尺寸尺度对球团破裂能量影响的能力。

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引用次数: 0

Role of particle shape in sheared granular media: Roundness and elongation 颗粒形状在剪切颗粒介质中的作用：圆度和伸长率

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-09 DOI: 10.1016/j.powtec.2024.120436

Usman Ali, Mamoru Kikumoto

Particle shape is an intrinsic characteristic of soil particles that significantly influences mechanical responses. In this investigation, a meticulously calibrated and validated two-dimensional discrete element method (DEM) model of a biaxial shearing test was employed to simulate the shearing response of forty distinct particle shapes. The systematic evolution of particle roundness (R) and aspect ratio (AR) was achieved by utilizing idealized polygonal-shaped particles, aiming to comprehend their effects on the macro and micromechanical behaviors of granular materials. The results suggest that a reduction in R limits free rotations and enhances interlocking, thereby promoting relatively stable force transmission between particles and leading to a monotonic increase in shear strength. However, this effect diminishes as particles become more elongated. Conversely, a decrease in AR from 1.0 (increased elongation) constrains particle rotations, increases the coordination number, and enhances fabric anisotropy initially resulting in increased overall shear strength, reaching a maximum before exhibiting a decreasing trend, indicative of non-monotonic variation. For high elongations, notable fabric anisotropy impedes clear force transmission between particles thus facilitating interparticle sliding and overall strength diminishes. The extent to which AR impacts depends on the angularity feature of particles. Finally, a nonlinear equation has been proposed to predict the variation in critical state shear strength of granular samples, based on the R and AR values of the constituent particles.

颗粒形状是土壤颗粒的固有特征，对机械响应有重大影响。在这项研究中，采用了经过精心校准和验证的双轴剪切试验二维离散元法（DEM）模型，模拟了 40 种不同形状颗粒的剪切响应。利用理想化的多边形颗粒实现了颗粒圆度（R）和长宽比（AR）的系统演化，旨在理解它们对颗粒材料宏观和微观机械行为的影响。结果表明，R 的减小限制了自由旋转并增强了连锁，从而促进了颗粒间相对稳定的力传递，并导致剪切强度的单调增加。然而，当颗粒变得更加细长时，这种效果就会减弱。相反，AR 值从 1.0 开始下降（伸长率增加）会限制颗粒的旋转，增加配位数，并增强织物的各向异性，最初会导致整体剪切强度增加，在达到最大值后呈现下降趋势，这表明存在非单调变化。当伸长率较高时，织物明显的各向异性会阻碍颗粒间清晰的力传递，从而促进颗粒间的滑动，整体强度也随之降低。AR 的影响程度取决于颗粒的角度特征。最后，根据组成颗粒的 R 值和 AR 值，提出了一个非线性方程来预测颗粒样品临界状态剪切强度的变化。

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引用次数: 0

Evaluation of a new three-phase fluidised bed flotation column for industrial experiment study 用于工业实验研究的新型三相流化床浮选柱评估

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-09 DOI: 10.1016/j.powtec.2024.120435

Ning Han , Yifei Li , Zhiyuan Zhang , Jikang Han , Peng Chen , Yanfeng Li

Three-phase fluidized bed flotation column (TFC) is a new type of separation flotation method with high efficiency and low energy consumption. In this paper, the industrial experimental effect of TFC is investigated. The influence of operating parameters on the flotation separation effect was investigated by adjusting the operating parameters such as gas velocity, liquid velocity, and bed height. In addition, when the sampling depth and sampling radius are increased, the ash content in the selection zone increases with it. The relationship between the amount of mid-coal circulation and the ash content was also investigated. The ash content of refined coal gradually decreased from 10.28 % to 9.28 % when the amount of middle coal circulating was increased from 0 % to 50 % of the feed. This study explores the separation effect of TFC from industrial experiment perspective, which lays a good foundation for future industrial-scale applications.

三相流化床浮选柱（TFC）是一种高效、低能耗的新型分离浮选方法。本文研究了 TFC 的工业实验效果。通过调整气速、液速、床层高度等操作参数，研究了操作参数对浮选分离效果的影响。此外，当取样深度和取样半径增大时，选择区的灰分含量也随之增加。还研究了中煤循环量与灰分含量之间的关系。当中煤循环量从进料的 0 % 增加到 50 % 时，精煤的灰分含量从 10.28 % 逐渐下降到 9.28 %。该研究从工业实验的角度探索了 TFC 的分离效果，为未来工业规模的应用奠定了良好的基础。

引用次数: 0

The effect of impeller speeds on the nanobubbles flotation efficiency of ultrafine coal particles 叶轮速度对纳米气泡浮选超细煤粒效率的影响

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-08 DOI: 10.1016/j.powtec.2024.120431

Hanyue Jiang , Haichang Yang , Yaowen Xing , Yijun Cao , Xiahui Gui

Ultrafine particles exhibit poor flotation behavior due to the low collision efficiencies with conventional gas bubbles. Introducing nanobubbles are expected to improve the collision probability of ultra-fine particles with bubbles. However, it remains unclear whether nanobubbles can enhance flotation at high impeller speeds during flotation process as strong turbulence may scour away the nanobubbles from solid-liquid interface of particles. This study investigates the influence and the underlying mechanism of nanobubbles on flotation performance of ultrafine coal particles under varying impeller speeds. Specifically, the surface nanobubbles (SNBs) and bulk nanobubbles (BNBs) were utilized respectively, which were produced based on the temperature difference method and hydrodynamic cavitation, and characteristized by atomic force microscopy (AFM) and nanoparticle tracking analysis (NTA), respectively. The formation of ultrafine coal particle aggregates at different impeller speeds was analyzed through laser particle size analyzer (LPSA) and high-speed camera imaging. Result showed that as the impeller speed increases, the radius of the aggregates increases, and the number and radius of aggregates in SNBs/BNBs slurries is significantly larger than that in conventional slurry at varying impeller speeds from 1200 to 2800 rpm, which is consistent with the increased flotation recoveries and flotation rates. It is demonstrated that nanobubbles remain stable even at high impeller speeds, and thus promote aggregation and thereby enhance flotation performance. The findings of this study provide theoretical support and valuable insights for ultrafine particle separation technologies.

由于与传统气泡的碰撞效率较低，超细颗粒的浮选性能较差。引入纳米气泡有望提高超细颗粒与气泡的碰撞概率。然而，纳米气泡能否在浮选过程中的高叶轮速度下增强浮选效果仍不清楚，因为强大的湍流可能会将纳米气泡从颗粒的固液界面冲走。本研究探讨了纳米气泡在不同叶轮速度下对超细煤颗粒浮选性能的影响及其内在机理。具体而言，研究分别采用了基于温差法和流体动力空化法产生的表面纳米气泡（SNBs）和体纳米气泡（BNBs），并分别用原子力显微镜（AFM）和纳米颗粒跟踪分析（NTA）对其进行了表征。通过激光粒度分析仪（LPSA）和高速相机成像分析了不同叶轮转速下超细煤颗粒聚集体的形成。结果表明，随着叶轮转速的增加，聚集体的半径也随之增加，在 1200 至 2800 rpm 不同叶轮转速下，SNBs/BNBs 浆料中聚集体的数量和半径明显大于常规浆料，这与浮选回收率和浮选率的提高是一致的。研究表明，纳米气泡即使在较高的叶轮转速下也能保持稳定，从而促进聚集，进而提高浮选性能。该研究结果为超细颗粒分离技术提供了理论支持和宝贵见解。

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引用次数: 0

Numerical investigation on compaction operations of railway gravel ballast based on DEM-MBD coupling method 基于 DEM-MBD 耦合方法的铁路碎石道碴压实作业数值研究

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-08 DOI: 10.1016/j.powtec.2024.120428

Zhihai Zhang , Hong Xiao , Qiang Liu , Yang Wang , Zhongxia Qian , Mahantesh M. Nadakatti

Compaction is an essential process in the maintenance of ballasted railways. However, unreasonable operating parameters can reduce compaction efficiency and increase maintenance costs. Previous studies have hardly addressed the impact of compaction on improving the mechanical properties of the ballast bed. In the study, the dynamic equations of compaction are established, and a novel model of compaction based on DEM-MBD coupling method is developed. Furthermore, the parameters of the compaction are optimized from a macro and micro perspective. The research results show that the compaction mainly increases the coordination number of the ballast in the upper area of the ballast shoulder, and the maximum growth rate is 17.45 %. The study reveals that there is no positive correlation between the compacting effect and the excitation frequency. The optimal frequency range for compaction is 25–32 Hz. This study can provide key theoretical support for the parameter selection of on-site compaction for line maintenance.

压实是维护有砟铁路的重要工序。然而，不合理的操作参数会降低压实效率，增加维护成本。以往的研究几乎没有涉及压实对改善有砟道床力学性能的影响。本研究建立了压实动态方程，并开发了基于 DEM-MBD 耦合方法的新型压实模型。此外，还从宏观和微观角度对压实参数进行了优化。研究结果表明，压实主要增加了道碴肩上部区域道碴的配位数，最大增长率为 17.45%。研究表明，压实效果与激振频率之间不存在正相关关系。压实的最佳频率范围为 25-32 Hz。这项研究可为线路维护现场压实的参数选择提供重要的理论支持。

引用次数: 0

CFD-DEM simulation study on the bed dynamics of a binary mixture with super-quadric particles in a fluidized bed 流化床中超四边形颗粒二元混合物的床层动力学 CFD-DEM 模拟研究

IF 4.5 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology

Pub Date : 2024-11-08 DOI: 10.1016/j.powtec.2024.120425

Ju Wang , Guirong Bao

In biomass thermal conversion processes such as pyrolysis and gasification, biomass often takes on a cylindrical shape. However, most previous studies have modeled biomass as spherical, leaving the fluidization and mixing behaviors of non-spherical biomass particles with approximately spherical bed materials insufficiently explored. To bridge this gap, a super-quadratic particle model coupled with CFD-DEM was used to explore the fluidization characteristics and mixing dynamics of non-spherical binary mixtures. The numerical model successfully validated the pressure drop and spatial distribution within the binary mixture. The results indicate that particle mixing is primarily driven by the rise and movement of bubbles. The large aspect ratio of the cylindrical particles, combined with the narrow thickness of the 2D rectangular fluidized bed, leads to a significant interlocking effect during fluidization. This interlocking hinders both fluidization and mixing, resulting in poor overall performance for non-spherical particles. At a low superficial velocity (U_g), only the cylindrical particles in the lower part are fluidized as a result of the rising central bubble. The two particle types achieve effective mixing as the U_g rises to a high value. The mixing index increases from 0.78 to 0.94 as the U_g increases from 1.8 to 2.1 m/s. However, the stacking pattern of cylindrical particles creates a dead zone at the bed bottom, occupied solely by spherical particles, which limits local bed mixing and fluidization. As the U_g increases from 1.8 to 2.1 m/s and the dimensionless inventory height increases from 0.6 to 1.0, the axial dispersion coefficient of the cylinders increases from 1.17

\times

10⁻³ to 4.35

\times

10⁻³ m²/s and from 1.91

\times

10⁻³ to 9.22

\times

10⁻³ m²/s, respectively. This study provides new insights into the behavior of non-spherical particles, offering potential avenues for optimizing chemical engineering processes.

在热解和气化等生物质热转化过程中，生物质通常呈圆柱形。然而，以往的研究大多将生物质建模为球形，对非球形生物质颗粒与近似球形床层材料的流化和混合行为探讨不足。为了弥补这一不足，我们采用了超二次粒子模型与 CFD-DEM 相结合的方法来探索非球形二元混合物的流化特性和混合动力学。数值模型成功验证了二元混合物内的压降和空间分布。结果表明，颗粒混合主要由气泡的上升和运动驱动。圆柱形颗粒的高宽比与二维矩形流化床的窄厚度相结合，在流化过程中产生了显著的互锁效应。这种交错既阻碍了流化，也阻碍了混合，导致非球形颗粒的整体性能不佳。在较低的表面速度（Ug）下，由于中心气泡的上升，只有下部的圆柱形颗粒被流化。当表层速度（Ug）上升到较高值时，两种颗粒类型实现了有效混合。当 Ug 从 1.8 m/s 上升到 2.1 m/s 时，混合指数从 0.78 上升到 0.94。然而，圆柱形颗粒的堆叠模式在床底形成了一个死区，仅由球形颗粒占据，这限制了床层的局部混合和流化。随着 Ug 从 1.8 m/s 增加到 2.1 m/s，无量纲库存高度从 0.6 增加到 1.0，圆柱的轴向分散系数分别从 1.17×10-3 m2/s 增加到 4.35×10-3 m2/s 和从 1.91×10-3 m2/s 增加到 9.22×10-3 m2/s。这项研究为非球形颗粒的行为提供了新的见解，为优化化学工程工艺提供了潜在的途径。

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