Simulation of Magnetohydrodynamic Multiphase Flow Phenomena and Interface Fluctuation in Aluminum Electrolytic Cell with Innovative Cathode

A three-dimensional (3D) transient mathematical model has been developed to understand the effect of innovative cathode on molten cryolite (bath)/molten aluminum (metal) interface fluctuation as well as energy-saving mechanism in aluminum electrolytic cell with innovative cathode. Based on the finite element method, the steady charge conservation law, Ohm’s law, and steady-state Maxwell’s equations were solved in order to investigate electric current field, magnetic field, and electromagnetic force (EMF) field. Then, an inhomogeneous multiphase flow model of three phases including bath, metal, and gas bubbles, based on the finite volume method, was implemented using the Euler/Euler approach to investigate melt motion and bath/metal interface fluctuation. EMF was incorporated into the momentum equations of bath and metal as a source term. Additionally, the interphase drag force was employed to consider different phase interactions. Thus, present work owns three main features: (1) magnetohydrodynamic multiphase flow are demonstrated in detail both in aluminum electrolytic cell with traditional cathode and innovative cathode; (2) bath/metal interface fluctuation due to different driving forces of gas bubbles, EMF, and the combined effect of the two driving forces is investigated, which is critical to the energy saving; and (3) the effect of innovative cathode on melt flow and motion of gas bubbles. A good agreement between the predicated results and measurement is obtained. The velocity difference leading to the melt oscillation decreases due to more uniform flow field. The average velocity of metal in the cell with innovative cathode decreases by approximately 33.98 pct. The gas bubbles in the cell with innovative cathode releases more quickly under the effect of protrusion on the cathode. The average bubble release frequency increases from 1.1 to 1.98 Hz. Hence, the voltage drop caused by gas bubbles would decrease significantly. In addition, the two large vortices are broken into many small vortices due to the protrusion. The final disappearance of the small vortices as a result of viscous dissipation is conducive to the suppression of bath/metal interface fluctuation. The average interface amplitude in the cell with innovative cathode reduces to 75.95 pct of that in the cell with traditional cathode.     

山铝电解铝厂电解槽设计特点

山铝电解铝厂在技术改造中采用200kA预焙阳极电解槽取代60kA自焙槽,该槽型具有优异的磁流体稳定性,合理的电热场设计,采用了窄加工面、阳极升降、“船形”槽壳、实腹板梁等多项先进技术和高性能的内衬材料。目前,电解槽已连续生产986天,电流效率达到了94.5%,吨铝直流电能消耗13100 kW.h,氟化氢和粉尘等主要污染物排放量全部达到了国家排放标准。     

350kA铝电解槽焙烧自动分流装置的设计与实现

针对当前铝电解槽焙烧过程中手动通断分流片及人工记录数据存在控制精度低、焙烧效果不理想的问题,设计了一套焙烧分流自动控制系统。对焙烧过程中分流器的分流量变化、温度变化、分流效果和分流片的散热性能以及分流开关装置中动、静触头打火情况进行大量试验并做出深入研究。结果显示,该焙烧分流系统能够满足350kA铝电解槽焙烧启动的要求。     

铝电解槽专用操作机组的发展和设计方法探讨

介绍了铝的基本特点、应用范围领域和重要作用,对铝的电解法提取起源进行了简述,并详细叙述了铝电解生产原理,指出当今节能环保政策条件下铝电解专用操作机组的瓶颈问题.简单总结了电解铝的一般工艺过程,并针对当前形势和环保节能政策要求,分析总结了铝电解行业将来的发展方向和趋势.总结了现有铝电解槽专用操作机组的结构和特点,以及国内机组的发展历程.通过简单说明电解槽电解生产过程中的基本操作要求,分析现场实际操作需求和节能环保需要,结合铝电解多功能机组的结构、功能、应用和技术现状,提出新一代铝电解槽专用操作机组的基本需求、功能和发展方向.     

电解铝液生产铝合金扁锭工艺技术研究与实践

探讨了用电解铝液直接生产铝合金扁锭的工艺技术以及由此产生的经济效益。     

铝电解生产中降低电解槽平均电压的措施

介绍了影响电解槽平均电压的因素,结合铝电解生产实际工艺技术条件及操作内容,提出了降低电解槽平均电压的一些措施和方法,通过该类措施的执行可有效降低电解槽生产电耗,并可取得一定的经济效益.     

工业铝灰返回电解槽后的去向研究

工业铝灰中的主要成分为氧化铝和铝.如果回收的铝灰能返到电解槽作为原料使用,将为铝电解厂节约成本,减少废料排放,铝回收变成产品,最大限度实现经济效益.本研究用某电解铝厂电解槽中的电解质与铸造过程产生的细铝灰按照一定比例混合放入坩埚中,利用实验室的熔化炉模拟电解槽中的温度环境,对铝灰返回电解槽后的去向做了一些试验性的研究和探索,并结合试验结果对铝灰返电解槽给出了一些建议.     

石墨化阴极在400kA系列电解槽的应用

作为以电力、炭阳极、氧化铝为主力需求的高耗能电解铝企业,为积极响应国家“碳达峰,碳中和”战略目标,某公司率先通过技改措施以达到减碳降耗,采用高导电钢棒、高导电石墨化阴极炭块、强保温底层内衬材料等优化改造方案提高电能利用率,降低综合电耗。以400 kA系列铝电解槽为研究对象,探索石墨化阴极内衬在400 kA系列电解槽上的生产应用研究。石墨化阴极炭块相比石墨质阴极炭块具有更优良的导电性和导热性,可以提高电流效率和电解槽稳定性,阴极压降、平均电压、效应系数和交直流电耗明显降低,电解槽槽寿命亦有所延长,实现了电解槽内衬优化、节能降耗的目标。     

抗氧化防腐涂料在预焙阳极铝电解槽上的应用

主要介绍了抗氧化防腐涂料在400 kA系列预焙阳极铝电解槽预焙阳极及钢爪表面上涂刷(或喷涂)应用,分析、验证抗氧化防腐涂料对预焙阳极及钢爪的抗氧化防腐效果。结果表明,阳极抗氧化防腐涂料具备良好的抗氧化性,刷涂抗氧化防腐涂料的阳极,无阳极氧化和阳极钢爪被氧化和侵蚀现象,可延长阳极换极周期至少1天以上。     

Simulation of the Aluminum Electrolysis Process in a High-Current Electrolytic Cell in Modern Software

Metallurgist - A three-dimensional nonstationary model of a 600 kA electrolytic cell is described. The mathematical model describes the electrolysis processes occurring in the cell. The assumptions...     

降低预焙铝电解槽炉底压降的途径探索

炉底压降是影响预焙铝电解槽生产电流效率主要因素,通过分析实际生产过程中炉底压降的原因,得出炉底压降结构的材质选取和电解工艺参数是影响炉底压降主要原因,只有合理选取炉底压降结构的材料,优化电解工艺参数,才能有效地控制炉底压降,保证预焙铝电解槽的稳定运行和较高的电流效率,为实际生产提供了可靠的参考技术。     

铜电解槽内铜离子浓度分布调查

对电解槽内铜离子浓度进行取样分析,探讨了下进上出循环方式槽内电解液铜离子浓度分布情况和影响因素,介绍了改进措施和改进效果。     

惰性可湿润性TiB2阴极材料在铝电解槽中的应用

TiB2具有熔点高,导电性好,能被金属铝液良好润湿,且能抗拒电解质和金属铝液的腐蚀与渗透,是铝电解首选的惰性阴极材料。介绍了TiB2涂层阴极、TiB2复合阴极以及TiB2陶瓷阴极材料的研究现状和惰性阴极材料在工业铝电解槽上的应用情况。     

330 kA铝电解槽异形阴极碳块对水平电流的影响

采用有限元仿真计算,对330 kA铝电解槽进行传统阴极碳块结构和异形阴极碳块结构的电场进行仿真模拟,主要对铝液中水平电流分布进行分析。研究发现,异形阴极碳块结构相对于传统阴极碳块结构能够在影响压降较小的前提下降低水平电流密度。模拟结果表明,在异形阴极碳块表面凸起中增加隔断并改变凸起角度,对降低铝液中水平电流效果明显,能够降低铝液中最大水平电流密度27.8%,平均水平电流密度34.3%,有效提升了铝电解槽电流效率。     

400 kA铝电解槽异形阴极炭块对阴极电压降的影响

传统阴极炭块顶部是平坦的,阴极铝液流动时几乎没有阻力。使用表面凸起的阴极炭块进行研究,目的是增加铝电解槽中铝液流动的阻力,起到减波和减少铝液流动速度的作用,以此降低水平电流密度、阴极电压和铝液流速,保障铝电解槽生产安全稳定。通过COMSOL软件进行模拟,发现随着阴极炭块表面凸起块数的增加,阴极压降和水平电流密度均呈下降趋势,其中阴极压降最大降幅为39.8 mV,水平电流密度最大降幅为2 087 A/m2,并对某铝厂400 kA铝电解槽使用异形阴极炭块后进行测试,测试结果与模拟结果一致。     

Study on the Anode-to-Cathode Distance in an Aluminum Reduction Cell

A two-dimensional (2D) finite element model (FEM) of an anode immersed in an aluminum reduction cell was developed to study the initial current distribution in the anode as a function of anode geometry and electrical anode conductivity gradients. The numerical results of the initial state of the anode electrical current were used to describe analytically how this will affect the variation in the anode-to-cathode distance (ACD) in a steady-state scenario after several hours in the electrolysis bath. The electrical power loss in the anode has also been studied at different anode geometries and material properties. The slot positioning, slot depths, and stub hole dimensions have been considered in the FEM. The anode is implemented as an inhomogeneous orthotropic material with a defined six-parameter equation. The degree of initial inhomogeneous anode current density, which is expressed with a defined parameter k ₀, can reach values to cause variations in the ACD typically measured in the aluminum industry. To avoid a variation in the ACD for this case, the defined bath conductivity relation n should be within certain limits for the analyzed industrial reduction cell. The lowest degree of initial inhomogeneous current in the anode is achieved with deeper slots closer to each other and with an electrical current entering the anode in the bottom of the anode stub hole.     

铝电解槽生产工艺计算机控制技术优化应用

铝电解不仅属于高耗能、高污染行业,国家产业政策对其严格限制,而且在经济形势低迷、产能严重过剩的情况下,诸多新兴企业以技术、装备、资金及成本等优势占据了市场主动,相对而言,投产较早、相对落后的企业或系列则处境艰辛,本文以铝电解槽生产工艺为根本,加强其计算机控制技术,对铝电解槽生产工艺技术调整的实践予以浅析。     

An Approach for Estimation of Cathode Voltage Drop in an Aluminum Reduction Cell with an Inclined Carbon Block and a Copper Insert

Numerical models of a cathode block assembly in a Hall–Hèroult cell, comprising of liquid aluminium, carbon block, current collector, ramming paste and a copper insert were built and the finite element method simulations were carried out to model the cathode voltage drop (CVD), the current distribution and, the effect of geometrical parameters on the CVD. The objective of the study was to quantify the drop in the CVD for different cathode assembly design. Flat- and inclined-interface carbon block top-surface and a copper insert versus the conventional insert-free designs were simulated with a myriad of other geometrical parameters to optimise the design. The results informed about the optimum insert positioning to about 75 mm from the collector base and the energy saving possibilities due to reduction in the CVD with a cathode design with inclined-interface carbon block and copper insert in the collector bar.     

氧化铝含量对电解铝生产主要技术参数的影响

在有限的测量和分析条件下,通过对大型预焙铝电解槽的氧化铝含量的分析研究,指出目前在控制技术条件下,测量与控制过程中存在的误区和盲区,以便更好地实现电解铝生产稳定高效的目的,为300KA以上铝电解槽稳定运行提供一定的指导意见。     

铝电解槽电、磁、流场数值计算方法的进展

介绍了国内外铝电解槽电、磁、流场数值计算方法的研究现状，并指出其存在的不足主要在于电、磁、流场分开计算，提出了铝电解槽电、磁、流场耦合数值计算的思维方法。