共查询到20条相似文献,搜索用时 10 毫秒
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Alexandru Iuga Simona Vlad Michaela Mihailescu Lucian Dascalescu 《Particulate Science and Technology》2004,22(3):275-283
The plate/screen-type electrostatic separator presented in this article provides a user-friendly environment for the experimental modeling of existing industrial units and facilitates investigations aiming at identifying new possibilities for using electric field forces for processing mixed granular solids. This multifunctional unit can be equipped with two different active electrodes, which can be energized from one or two independent high-voltage supplies, and the operator has the choice between two types of grounded electrodes: plate and plate/screen. The experiments carried out on a 50% quartz-50% magnetite mixture demonstrate that the efficiency of the separation can be increased by using a grounded plate/screen electrode and two high-voltage electrodes, energized from different supplies. 相似文献
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D. Saini S. Trigwell P. K. Srirama R. A. Sims R. Sharma 《Particulate Science and Technology》2013,31(4):349-360
A portable free-fall electrostatic separator capable of analyzing gram quantities of charged powders is presented. Unlike a Faraday pail, in which only the net average charge-to-mass (Q/M) ratio of the particles sampled by the instrument is measured, an electrostatic separator is capable of separately measuring the charge-to-mass ratios of positively and negatively charged sampled powders. Thus, with an electrostatic separator it is possible to measure the mass fractions of powders that are charged with different polarities and the respective charge-to-mass ratios, along with the mass fraction of particles that are uncharged or charged below a threshold level. We describe a method of measuring the total charge of the collected particles in real time by incorporating an electrometer to integrate the current flowing through the collecting electrode to the high voltage power supply. In this manner, both the total charge and total mass of powder deposited on the two electrodes are measured in near real time, providing information on charge-to-mass ratio of the aerosol cloud sampled. Such real time measurements are often needed to analyze the electrostatic charging properties of small quantities of dispersed powder, particularly in such applications where the charge characteristics are of high importance. 相似文献
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The paper aims at optimizing the operation of a free-fall electrostatic separator equipped with a novel tribo-charging device for the processing of granular plastic mixtures. Experiments were performed with a mixture of polycarbonate and polyamide granules (cylinders of 1.5 mm in diameter and 3 mm in length). The samples of granules to be charged were introduced in the gap between the two co-axial cylinders of the tribo-charging device, and were put into turbulent motion for 30 s by two oppositely oriented air jets (pressure: 2 bar). Then, the charged particles were left to fall freely between the vertical plate electrodes of an electrostatic separator. A composite experimental design enabled the modeling and optimization of the tribo-electrostatic separation process as a function of the following control factors: applied high voltage, inter-electrode distance, and the inclination angle of the feeding device. Under optimal conditions, the purity obtained is close to 99%. A numerical model of particle trajectories confirms the conclusions of the experimental study. The simulations point out the effect of each control variable on the outcome of the separation process. 相似文献
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This article aims to identify the appropriate sampling duration for a tribocharging process on a vibratory feeder device in order to compute the capability indexes and set up a statistical control procedure. The outcome of the process is evaluated as the ratio between the charge and the mass of the granules that exit the tribocharging device during a given laps of time. A virtual instrument developed in LabWiew was used in conjunction with a Faraday cage connected to an electrometer and with an electronic scale, to simultaneously measure the charge and the mass of tribocharged granular plastics, for fixed sampling durations. 相似文献
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C. U. YURTERI M. K. MAZUMDER N. GRABLE G. AHUJA S. TRIGWELL A. S. BIRIS 《Particulate Science and Technology》2013,31(1):59-79
Currently, there is no standard method for testing the electrostatic properties of pharmaceutical powders. The objective of this study was to develop a method of characterizing the dispersion, charging, and transport properties of fine powder flowing through tubes of different materials. Powders of known composition and size distribution were dispersed pneumatically and transported through a short section of tubing containing spiral baffle inserts of the same material to simulate powder flow in long sections of horizontal and vertical tubes with bends. The test powder was dispersed using ring jet suction and passed through the baffled tube to a sampling chamber, from which the powder cloud was sampled for particle size and electrostatic charge distribution measurement using an Electrical Single Particle Aerodynamic Relaxation Time (E-SPART) analyzer. Experimental data on the tribocharging and transport properties of different powders are presented along with an explanation of the charging mechanisms. Analyses of particle size and electrostatic charge distributions in real time and on a single particle basis using the E-SPART analyzer coupled with surface structure analyses with XPS and UPS showed that: (1) most powders are charged bipolarly with relatively high charge-to-mass ratio (Q/M) values that would have a strong effect on transport and deposition of powders; and (2) surface structures, particularly adsorbates, influence the work function and tribocharging of powder. Different methods, including plasma treatment, with minimal changes or contamination of the bulk properties of the powders are also suggested. pharmaceutical powders tribocharging dispersion work function charge distributions charge decay plasma treatment 相似文献
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Granular Nanostructure: A Facile Biomimetic Strategy for the Design of Supertough Polymeric Materials with High Ductility and Strength 下载免费PDF全文
Pingan Song Zhiguang Xu Matthew S. Dargusch Zhi‐Gang Chen Hao Wang Qipeng Guo 《Advanced materials (Deerfield Beach, Fla.)》2017,29(46)
The realization of high strength, large ductility, and great toughness for polymeric materials is a vital factor for practical applications in industry. Unfortunately, until now this remains a huge challenge due to the common opposing trends that exist when promoting improvements in these properties using materials design strategies. In the natural world, the cuticle of mussel byssus exhibits a breaking strain as high as 100%, which is revealed to arise from an architectural granular microphase‐separated structure within the protein matrix. Herein, a facile biomimetic designed granular nanostructured polymer film is reported. Such biomimetic nanostructured polymer films show a world‐record toughness of 122 (± 6.1) J g?1 as compared with other polyvinyl alcohol films, with a breaking strain as high as 205% and a high tensile strength of 91.2 MPa, which is much superior to those of most engineering plastics. This portfolio of outstanding properties can be attributed to the unique nanoscale granular phase‐separated structure of this material. These biomimetic designed polymer films are expected to find promising applications in tissue engineering and biomaterials fields, such as artificial skin and tendon, which opens up an innovative methodology for the design of robust polymer materials for a range of innovative future applications. 相似文献
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The rheological properties for dilute and moderately dense granular binary mixtures of smooth, inelastic hard disks/spheres under uniform shear flow in steady state conditions are reported. The results are based on the Enskog kinetic theory, numerically solved by a dense gas extension of the Direct Simulation Monte Carlo method for dilute gases. These results are confronted to the ones also obtained by performing molecular dynamics (MD) simulations with good agreement for the lower densities and higher coefficients of restitution. For increasing density and dissipation, the Enskog equation applies qualitatively, but the quantitative differences increase. Possible reasons for deviations of Enskog from MD results are discussed, indicating non-Newtonian flow behavior and anisotropy as the most likely direction in which previous analytical approaches have to be extended. 相似文献
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M. F. Boukhoulda M. Rezoug W. Aksa M. Miloudi K. Medles 《Particulate Science and Technology》2017,35(5):621-626
The efficiency of the electrostatic separation of insulating granular mixtures depends on the electric charge carried by the particles. The first objective of this work was to characterize the tribocharging properties of various plastic materials in the composition of waste electric and electronic equipment: polyvinyl chloride (PVC), “high-impact” polystyrene (HIPS), acrylonitrile butadiene styrene (ABS), “high-density” polyethylene (HDPE), polycarbonate (PC), polyamide (PA). Thus, in a first series of experiments, 15 samples composed of binary mixtures of above plastics were initially charged in a fluidized bed device, then separated using a free-fall electrostatic separator. The six plastics could be ordered in a specific triboelectric series: PVC, HIPS, ABS, PEHD, PC, PA. The second objective was to evaluate the efficiency of three tribocharging devices: a static charger, a fluidized bed, and a fan-type device. The triboelectrostatic separation experiments performed with four different binary mixtures (PVC/PA, PC/PA, HIPS/PA, and HIPS/ABS) showed that the fluidized bed is the most effective. 相似文献
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在分析加权平均法、模糊综合评价法、TOPSIS法和灰色关联度评价法各自优缺点的基础之上,针对单一评价方法的不足,运用序号总和理论与众数理论,结合上述4种多指标评价方法,建立工程选材组合评价模式.以低温存储罐材料的选择为例,从功能性和经济性角度出发,选择了8种评价指标,由层次分析法得到10种候选材料的评价指标的权重,运用上述组合评价模式进行组合评价.结果表明,全硬态301型不锈钢是最佳的低温存储罐材料,与客现实际相符,且组合评价模式所得排序结果优于单一评价方法.在工程设计中使用组合评价模式进行选材评价,有助于弥补单一评价法的缺陷,是工程选材决策的有力工具. 相似文献
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Explosives: Metal‐Organic Framework Templated Synthesis of Copper Azide as the Primary Explosive with Low Electrostatic Sensitivity and Excellent Initiation Ability (Adv. Mater. 28/2016) 下载免费PDF全文
Qianyou Wang Xiao Feng Shan Wang Naimeng Song Yifa Chen Wenchao Tong Yuzhen Han Li Yang Bo Wang 《Advanced materials (Deerfield Beach, Fla.)》2016,28(28):5766-5766
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聚酰亚胺/TiO2 复合膜的制备、表征和气体渗透性测定 总被引:2,自引:0,他引:2
以硅藻土-莫来石陶瓷膜管为支撑体,以TiO2为过渡层,通过溶胶-凝胶法制备了负载型聚酰亚胺/TiO2复合膜.采用FTIR、NMR、TG/DTA、TEM、BET和气体渗透法对复合膜进行了表征和测试.结果表明:TiO2相通过与聚酰亚胺链上羧酸基支链发生键连形成有机无机组分交错分布的网状结构;复合膜具有良好的热稳定性和有机无机兼容性;相对于聚酰亚胺膜,复合膜对H2、CO2、N2和H2O具有较高的分离性;TiO2含量为15wt%的复合膜对H2/N2、C02/N2和H20/N2的分离因子分别为64.2、42.5和80.8. 相似文献
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Energy‐saving separation and purification of industrially important compounds with similar physical and chemical properties by novel molecular crystalline materials are of great importance and highly desired. Here a newly enlarged version of geminiarene, namely elongated‐geminiarene ( ElGA ), is first designed and synthesized. Taking advantages of both geminiarenes and biphenarenes, ElGA shows great features including scalable synthesis, nanometer‐sized cavity, rich blend of conformational features, and excellent solid‐state host–guest properties. Significantly, the functional crystalline materials of ElGA are highly effective in the separation of aromatics and cyclic aliphatics, showing a preference for dimethylbenzene over its corresponding hydrogenation products and paving a new avenue for separation science and industry. 相似文献
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Jiaqi Liu Kang Zhou Saif Ullah Jiafeng Miao Hao Wang Timo Thonhauser Jing Li 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(42):2304460
The purification of C2H4 from C2H6/C2H4/C2H2 mixtures is of great significance in the chemical industry for C2H4 production but remains a daunting task. Guided by powerful reticular chemistry principles, herein a systematic study is carried out to engineer pore dimensions and pore functionality of fcu-type Y-based metal–organic frameworks (Y-MOFs) through the construction of a series of eight new structures using linear dicarboxylate linkers with different length and functional groups. This study illustrates how delicate changes in pore size and pore surface chemistry can effectively influence the adsorption preference of C2H6, C2H4, and C2H2 by the MOFs. Importantly, clear relations between pore size/pore surface polarity and C2 adsorption selectivities of this series of MOFs are established. In particular, HIAM-326 built on a linker decorated with trifluoromethoxy group shows notably preferential adsorption of C2H6 and C2H2 over C2H4, with balanced C2H2/C2H4 and C2H6/C2H4 selectivities. This endows the compound with the capability of one-step purification of C2H4 from C2H6/C2H4/C2H2 ternary mixtures, which is validated by breakthrough measurements where high purity C2H4 (99.9%+) can be obtained directly from the separation column. Its adsorption thermodynamics and underlying selective adsorption mechanisms are further revealed by ab initio calculations. 相似文献