THEORETICAL INVESTIGATION ON BY-ONLY-CURRENT ELECTROMAGNETIC SEPARATION OF INCLUSION FROM MOLTEN METALS

The electromagnetic field under applied AC and DC current in round and rectangular pipe was systematically investigated, then a concept of 'equivalent current density' was proposed for evaluating the inhomogeneous electromagnetic pinch force, and the mono-component removal efficiency and the overall removal efficiency of inclusion were formulated. It is founded that flat pipe is superior to round pipe for the electromagnetic removal of inclusion, and DC current can get a higher removal efficiency than A C current due to absence of skin phenomenon. Under usual condition, a removal efficiency of 52% for 10μm inclusion or more than 92% for 20μm inclusion can be achieved by imposing a current density of 3×106A/m2 in a flat pipe.

In-situ A1/24Si Functional Graded Materials Prepared by Electromagnetic Separation

Cylinder-like in-situ AI/24Si FGMs were produced by using electromagnetic separating process. Si primary phase reinforced layer with volume fraction as high as 16 pct was formed at the outer region of the cylinder-like samples where the local hardness and wear resistance were enhanced remarkably. Moreover, both of strength and ductility in the inner region provided insurance of reliable strength for this as-cast gradient material. It indicated that general mechanical properties such as good wear resistance at the outer region and good ductility in the central part could be obtained with the optimized redistribution of the Si primary particles under the electromagnetic force.

Electromagnetic separation of primary iron-rich phases from aluminum-silicon melt

The difference of conductivity between primary iron-rich phases and aluminum melt has been used to separate them by electromagnetic force (EMF) which is induced by imposing a direct electric current and a steady magnetic field in molten Al-Si alloy. Theoretical analysis and experiments on self-designed electromagnetic separation indicates that primary needle-like β phases are difficult to separate; while primary α iron-rich phases can be separated by electromagnetic separation. Primary iron-rich phases have been removed from the melt successfully when the molten metal flows horizontally through separation channel. The iron content is reduced from 1.13% to 0.41%.

Continuous electromagnetic separation of inclusion from aluminum melt using alternating current

A novel scheme about the continuous electromagnetic purification of aluminum melt was put forward based on the utilization of a square separation pipe and a 50 Hz alternating current to produce electromagnetic force. It is experimentally found that with electrical current of 400 A/cm2, it takes only 10 s to remove 95% inclusion from aluminum melt. Comprehensive numerical simulations were carried out to investigate the dynamics mechanisms behind the process. The results show that the removal of inclusion is attributed to the cooperative effects of electromagnetic buoyancy and the secondary flow induced by the rotational electromagnetic force, and the removal efficient increases with the size of inclusion and the electrical current imposed. Theoretical predictions on the distribution and removal efficiency of inclusion were supported by the experiments.

Dynamic electromagnetic separation of iron-rich phase inclusions from Al alloy

Electromagnetic separation of the iron-rich phase inclusions from Al alloy was investigated. The influencing parameters including magnetic induction density, the section shape of the separating channel and the length of influential loop of the metal melt on the separation efficiency of iron-rich phase inclusions were studied. The results show that when the proper magnetic induction density (B=0.3T) is applied, rectangle separating channel is used, and the influential loop of the metal melt is long, high separating efficiency of the iron-rich phase inclusions can be obtained.

Study on Electromagnetic Transient Condition of EMU Passing by Phase-separation with Electric Load in High-speed Railway

Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on and impact current is analyzed systematically in this article. π-type equivalent circuit of feeding section is put forward in the analysis of overvoltage mechanism. Overvoltage and overcurrent model of passing by phase-separation with electric load are also built. Correctness of mechanism was validated by simulation. In addition, the methods to solve the influence on substations, transformers and protection devices in this process are put forward, which provides a new idea on passing by phase-separation with electric load technology.

Effects of melt viscosity on enrichment and separation of primary silicon from Al-Si melt

The effects of melt viscosity on the enrichment and separation of Si crystals from Al–Si melt during an electromagnetic solidification process were investigated. Both the enrichment efficiency and the separation were found to be strongly dependent on the melt viscosity. A high melt viscosity was beneficial to the enrichment of primary silicon, whereas a low melt viscosity facilitated the separation process. A new enrichment mechanism was proposed in order to clarify the influence of melt viscosity, and an improved process for achieving high-efficiency enrichment of Si crystals via control of the melt viscosity was also proposed. Additionally, the morphology of Si crystals was found to change from spheroidal to plate-like in shape owing to the difference in viscosities in different regions.

Physical simulation and theoretical analysis of migrating rate of inclusions in aluminum melt in electromagnetic field

Simulation law and physical simulation were used to study the kinematic behavior of inclusions in electromagnetic separation. It was found that velocity of spherical non metallic particles shares different functions in different Reynolds number range. The function of spherical particle’s velocity has been got by confirming the relationship between Reynolds number and resistance coefficient when Reynolds number is 0.2 ～10. For non spherical particles, the moving behavior is influenced by shape and orientation while spherical coefficient has nothing to do with the velocity of irregular particles. The influence of orientation of cuboid particle on the electromagnetic expulsive force has been indicated by numerical computation. [

Investigation of the oil-seawater mixed flow under an electromagnetic field

The electromagnetic separation method is a new approach to treat ship-based marine oily wastewater,in which oil droplets are dispersed in seawater(oil-seawater mixed flow).In order to clarify the separation process and determine the separation characteristics,the flow field and volume fraction of the oil droplets of the oil-seawater mixed flow under an applied electromagnetic field with different operating conditions were investigated by 2D numerical simulations with the Eulerian model.The results show that:(1)the downward Lorentz force causes seawater to flow downwards and the oil droplets to move upwards due to the electromagnetic separation force in the effective section of the separation channel;(2)the volume fraction of the oil droplets at the top of the outlet section increases with the current density,magnetic field,and the diameter of the oil droplet and decreases with the inlet velocity of the oily seawater.The results provide useful guidance for the design of electromagnetic separation devices of the oil-seawater mixed flow.

Numerical Analysis of Electromagnetic Control of the Boundary Layer Flow on a Ship Hull

In this article, electromagnetic control of turbulent boundary layer on a ship hull is numerically investigated. This study is conducted on the geometry of tanker model hull. For this purpose, a combination of electric and magnetic fields is applied to a region of boundary layer on stern so that produce wall parallel Lorentz forces in streamwise direction as body forces in stern flow. The governing equations including RANS equations with SST k-ω?turbulent model coupled with electric potential equation are numerically solved by using Ansys Fluent codes. Accuracy of this turbulent model of Fluent in predicting Turbulent flow around a ship is also tested by comparing with available experimental results that it shows a good agreement with experimental data. The results obtained for ship flow show that by applying streamwise Lorentz forces that are large enough, flow is accelerated. The results are caused to delay or avoid the flow separation in stern, increase the propeller inlet velocity, create uniform flow distribution behind the ship’s hull in order to improve the propeller performance, and finally decrease the pressure resistance and total resistance.

Separation efficiency of alumina particles in Al melt under high frequency magnetic field

The effects of separation time and magnetic induction intensity on the separation efficiency of alumina particles with diameters varying from 30 to 200 μm in aluminum melt were investigated. The experimental results show that the particle-accumulated layer is formed in the periphery of the solidified specimen when the diameter of the separated molten metal, the magnetic induction intensity and the separation time are 10 mm, 0.04 T and 1 s, respectively. When the separation time is 2 s, the particle-accumulated layer can be observed obviously and the separation efficiency is about 80%. There are few alumina particles in the inner of the solidified specimen when the separation time is 3 s. The separation efficiency higher than 85% can be achieved when the separation time is longer than 3 s. When the magnetic induction intensity is 0.06 T, the visible particle-accumulated layer can be formed in 1 s and the separation efficiency is higher than 95%. The experimental results were compared with the calculated results at last.

Continuous cleaning of A356 alloy melt using high frequency electromagnetic field

A set of device for electromagnetic separation (EMS) was designed and applied to process the continuous flowing melt. Tensile test was employed to compare effect of electromagnetic separation with that of the traditional processes. Compared with filtration by ceramic foam filter and process without filtration, multiple process combined with filtration and electromagnetic separation can effectively remove most of inclusions with diameter finer than 10 μm in A356 alloy casting, hence improve its tensile properties. After being processed by electromagnetic filtration, the tensile strength of A356 scrap is enhanced by 8.27%, approaching the level of fresh A356 alloy.

INFLUENCE OF ELECTROMAGNETIC STIRRING ON MACROSEGREGATION OF CAST IRON

Enrichment of massive graphite on lateral surface and evident macrosegregation along both longitudinal and axial directions were found by the influence of intense electromag- netic stirring during unidirectionally solidifying grey cast iron ingot.A secondary flow within the region near solidliquid interface seems to be the cause of axial segregation, and the solidification rate may also be influential in the macrosegregation.

REMOVE INCLUSIONS FROM ALUMINUM MELT INELECTROMAGNETIC FIELD

Electromagnetic separation of non-metallic inclusions from Al-Si melt is studied by theoretical analysis and experiments on self-designed electromagnetic separation apparatus. Metallographs and LECO Image Analysis System were used to analyze the content of alumina in aluminum alloy before and after electromagnetic separation. It is seen that removal effciency increases with the increase of electromagnetic force (EMF) and diameter of inclusion particles while decreases with the increase of melt velocity and height of separator. All alumina particles with diamete of 14μm have been removed successfully from the melt.

The Physics of the Phenomena of Electrical Induced Elements Separation in Solution of Salts in Liquid Polar Dielectric

In the work [1] is shown the possibility of the use the phenomena of the electrical-induced selective drift of cationic aquacomplexes in the water solution of the salts for creating of the new, non-electrode, power-saving technology of the solution enrichment by desired element. The development of the naturally-scientific basis of this technology has showed that inertial properties of formed in the solution over-molecular structural units—clusters depends from that’s dimensions. Dimensions of these clusters are in limits from scores of angstrom to fractions of micron, at the same time liquid mediums are the base of functioning both biological and technological systems. Thus, water solution of salt contains nanoparticles and biological and many technological systems are functioning with the assistance of nanoparticles. For example, the ordinary blood circulatory system or many of chemical processing. The casual or intentional action of aperiodic electric field on systems containing salts solutions produces some positive or negative effects. This work shows new approach for theoretical describing of salts solution in dielectric liquids and contains some data on the realized experiments.

基于微流控芯片的鼠伤寒沙门氏菌免疫磁分离

开发一种用于鼠伤寒沙门氏菌快速分离与富集的免疫磁分离微流控系统,该系统由微流控芯片、微控制器、电磁分离与混合模块组成,具备电磁驱动混合和磁分离功能,能够实现免疫磁珠与鼠伤寒沙门氏菌的快速孵育、分离与富集。在最优条件下,可以在13 min内实现对牛奶样品中浓度范围为2×10^(1)~2×10^(6) CFU/m L鼠伤寒沙门氏菌的快速捕获与分离,捕获率在33.3%~67.5%之间,最低检测限为20 CFU/m L。因此,这种高度集成的免疫磁分离微流控系统能够从复杂食品基质中迅速、准确地富集目标细菌,为食源性致病菌的快速检测提供了有效的解决方案,对于应对食源性疾病引发的公共卫生问题具有重要意义。

电磁耦合智能分层采油技术

针对现有分层采油工艺技术存在的不适应检泵作业、有效工作寿命短、通讯可靠性差等问题,提出了电磁耦合智能分层采油技术,研制了核心工具及配套工具,并开展了现场试验。采用生产和配产管柱分离的丢手管柱结构,当两管柱在井下对接后,利用电磁耦合原理实现管柱间电能与信号的近距离无线传输,为井下多个智能配产器供电,并实现双向通讯。研制了适应井下复杂工况的电磁耦合传能与通讯装置、智能配产器、地面控制器等核心工具,以及大通径丢手锚定器、油井过电缆封隔器等配套工具,实现了技术定型。在大庆油田完成10口井现场试验,两管柱井下对接快捷、可靠,电磁耦合传能与通讯装置工作稳定,实现了井下分层流量、压力、温度的实时监测和分层产液量调控,提高了储层认识程度,取得了增油、降含水的生产实效。

Magnetohydrodynamic study of electromagnetic separation of nonmetallic inclusions from aluminum melt

Magnetohydrodynamic flow around the nonmetallic inclusions in aluminum melt and the force exerted on the inclusions were explored by dimensional analysis and numerical calculations. Dimensional analysis shows that the invariant _f^2 A = {{JB\rho _f d_p^3 } \over {\mu _f^2 }} characterizes the force exerted on the inclusions and the flow intensity of the melt. The physical significance of A is represented as a modified particle Reynolds number that reflects the effects of electromagnetic force. The fluid flow around the particle becomes unstable when A>2×103. It is shown that the neglect of the inertial terms has little effect on the force exerted on the inclusions in the range of A≤1×106. However, the analytical solution of the maximum velocity inside the melt does not apply due to the appearance of turbulent flow in the case of A>2×103.

Electromagnetic Separation of Nonmetallic Inclusions From Liquid Steel by High Frequency Magnetic Field

The currernt work is to investigate the removal of nonmetallic inclusionsfrom liquid steel using electromagnetic separation.In experiments,a certain amount of aluminum was added to the molten steel in a crucible to generate aluminum inclusions.A layer of aluminum clusters were observed close to the wall of the crucible.Three dimensional electromagnetic field and fluid flow simulation indicated that particles moved to the wall of the crucible by the EM force and were entrapped at the inside wall of the crucible.

Separation of Particles From Molten Aluminum With High Frequency Electromagnetic Field

The currentstudy is to investigate the separation of non-metallic inclusions from molten aluminum with 53-63 kHz high frequency electromagnetic filed.In the experiments,aAl-SiC composite material- pure aluminum with a certain amount of dispersed SiC particles with 10-20 μm diameter- was used.Both laboratory experiments and numerical simulation were performed.It was observed that SiC particles were pushed to the boundary layer of the aluminum close to the wall of the crucible,and the thickness of the particle layer was approximately 1.0-1.5 mm and the area fraction of the particle layer was 9-15%of the entire horizontal cross section area.With separation time going on,the accumulation layer became thinner,and the accumulation layer density became higher.The numerical simulation indicated that the magnetic flux density is larger at top and bottom than other locations and very small at the center of the crucible,and the EM force mainly acted on the outside 0.004 m layer of the melt due to the effect of the skin effect.There were recirculation eddies at the top and bottom and close to the corner where the EM force was the largest.The speed of the flow was 11-13 mm/s at the corner of the top and bottom and was as small as 1 mm/s at the center of the crucible. Both the numerical simulation and the experimental observation showed that the top free surface was not flat, approximately 1.0 mm high at the center of the top surface by numerical simulation and 4.0 mm by the experimental observation.More particles were entrapped at the lower part of the crucible.