铝电解槽节能潜力分析与应用实践

铝电解槽的电能消耗量与平均电压和电流效率两个因素有关，降低槽电压或者提高电流效率，可降低铝电解槽直流电耗。通过系统测试系列电解槽电压平衡、能量平衡、电流效率，深入挖掘分析，提出了节能降耗技术措施。通过2台试验槽工业试验表明，试验槽平均电压3.819 V，电流效率92.89%，吨铝直流电耗12 251 kWh。与系列电解槽相比，平均电压降低99 mV，电流效率提高1个百分点，吨铝直流电耗降低455 kWh，节能效果显著。     

新型稳流保温铝电解槽节能技术及其工业应用效果

论文简单介绍了新型稳流保温铝电解槽节能技术的开发思路和基本内容,着重从电压优化、电解槽散热减少和效率提高方面分析该技术的应用效果和优势。本技术优化了电解槽的阴极结构,对电解槽的内衬结构进行了更加精细的设计。现场的技术人员对筑炉质量严格把关,确保电解槽长期稳定运行,并根据现场具体情况配套了工艺技术参数,实现电解槽的高效率低能耗运行。新型稳流保温电解槽平均槽电压3.853V,电流效率91.9%,铝液直流电耗12493.9kWh/tAl,较同系列普通槽降959.1kWh/tAl。     

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.     

240kA系列预焙铝电解槽低温低电压生产实践

240kA铝电解槽低温低电压生产过程中,通过实施优化工艺参数、过程控制优化升级、电解槽外部保温等措施,保证了低温低电压下生产的电解槽能量平衡,实现了电解槽稳定运行,逐步降低了槽平均电压,而电流效率几乎没有下降,最终降低了原铝综合交流电耗,实现了节能与减排的目标。     

新型阴极结构电解槽铝电解试验

针对传统铝电解槽极距已经达到低限,槽电压不能大幅度降低的关键技术难题,提出一种新型阴极结构铝电解槽.介绍了这种新型阴极结构电解槽的特点和工艺技术特征,以及在重庆天泰铝业公司168 kA电解槽上进行工业电解槽试验的结果.统计期内3台试验电解槽平均槽电压为3.803 V,平均直流电耗比同系列其他127台传统电解槽低1 250 kW · h/t Al,达到1 2101 kW · h/t Al.     

新型节能电解槽非正常期的控制研究及应用

针对500 kA新型节能电解槽非正常期的特点，研究工艺参数控制范围，采取操作与维护管理措施，启动后的电解槽槽平均电压≤3.88 V，电流效率≥93%，具有较好的节能效果，为同类槽型非正常期管理控制提供实践经验。     

新型稳流保温铝电解槽节能技术开发及在某400kA电解系列推广应用

主要介绍了新型稳流保温铝电解槽节能技术的研究成果及在某400kA系列推广应用情况。新型稳流保温铝电解槽节能技术主要包括电压平衡优化技术、阴极稳流优化技术和能量平衡设计优化技术。新型稳流保温铝电解槽节能技术在某企业400kA系列电解槽上推广应用结果表明,新技术槽进入正常期内系列电流效率92.22%,平均电压3.882V,吨铝直流电耗12 543kWh,平均炉底压降267mV。与传统槽相比,新技术槽平均电压降低86mV,吨铝直流电耗降低507kWh,炉底压降降低44mV。     

无隔板镁电解槽的节能探讨

本文主要分析了无隔板电解槽的节能问题,探讨了降低电解槽电压、减少电解槽漏电等对无隔板镁电解槽能耗的影响,指出了影响电解槽工作电压的有关因素及降低电解槽工作电压的途径。     

槽控箱参数设定对电解槽运行影响分析

通过分析槽控箱设定电压、加料间隔、效应间隔、浓度参数等参数对电解槽运行的影响,提出合理的参数设定办法,实现电解槽长期稳定运行,达到节能降耗、延长槽寿命的目的。     

降低预焙阳极铝电解槽压降实践

本文结合国内某公司铝电解生产实际情况,提出降低预焙阳极铝电解槽压降措施,实施后电解槽平均电压和直流电单耗等指标得到了较大提高。     

低温铝电解的研究

综述了低温铝电解的研究进展，分析了电解质组成对电解质物理化学性质的影响以及低温铝电解与节能的关系。指出氧化铝的溶解度小且溶解速度慢、电解质导电性差以及阴极结壳是实现低温铝电解所要解决的主要问题，提出了今后的研究方向。     

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.     

Simulation of flow in a continuous galvanizing bath: Part II. Transient aluminum distribution resulting from ingot addition

The coupled phenomena of momentum, heat, and mass transfer were simulated in order to predict and to better understand the generation and movement of intermetallic dross particles within certain regions of a typical galvanizing bath. Solutions for the temperature and aluminum concentration can be correlated with the solubility limits of aluminum (Al) and iron (Fe) to determine the amount of precipitated aluminum in the form of Fe₂Al₅ top dross. Software developed by the Industrial Materials Institute of the National Research Council of Canada (IMI-NRC), including k-ε turbulence modeling for heat and mass transfer, was adapted for the simulation of a sequence of operating parameters. Each case was modeled over a period of 1 hour, taking into account an ingot-melting period followed by a nonmelting period. The presence of an ingot significantly changes the temperature distribution and also results in important variations in the local aluminum concentration, since the makeup ingot has a higher aluminum concentration. The simulation showed that during the ingot melting, the total aluminum concentration is higher at the ingot side of the bath than at the strip exit side. The region below the ingot presents the highest aluminum concentration, whereas lower aluminum concentrations were found in the region above the sink roll, between the strip and the free surface. It was shown that precipitates form near the ingot surface because this region is surrounded by a solution at 420 °C, which is lower than the average bath temperature of 460 °C. When no ingot is present, the total aluminum concentration becomes much more uniform and decreases with time at a constant rate, depending on the coating thickness. This information is of major significance in the prediction of the formation of dross particles, which can cause defects on the coated product.     

400 kA电解槽使用次品阳极的试验研究

碳素厂生产阳极有部分次品阳极,一般碳素阳极生产企业均采取返厂破碎,重新烧结的方式来处理,这样增加了大量的生产成本,也降低了企业的产出率。近几年电解铝产能过剩,多数电解铝企业严重亏损,“降本降亏”成了多数企业的核心任务。本文从电解车间400 kA电解槽使用本公司碳素厂生产的次品阳极,试验分析对电解槽的技术条件、经济指标的影响,为公司研究“直接使用次品阳极”是否可行提供依据。     

数值模拟氧气底吹熔炼工艺参数优化

采用数值模拟方法，分别研究熔池深度、气体流量、氧枪倾角、氧枪直径等参数变化对熔池气含率、熔体平均速度和平均湍动能的影响.结果表明:当熔池深度为1.3~1.5 m时，熔池内部气液两相搅拌强烈，气含率存在较大值为17.5 %，熔池处于较好的运动状态；气含率、熔体平均速度和平均湍动能随气体流量的增加呈现先减小后增大趋势，选取适宜气体流量为0.6~0.7 kg/s；熔池气含率随氧枪倾角的逐渐增大先增大后减小，而熔体平均运动速度和平均湍动能呈现先减小后增大趋势，选取适宜氧枪倾角为20°~25°；氧枪直径为30~35 mm时，熔池气含率和平均湍动能处于较大值，约为13 %和0.8 m2/s2，熔池处于较好的运动状态.      

On convection in aluminum reduction cells

The convection pattern in the bath electrolyte and the cathode metal of 150 kamp prebaked anode aluminum reduction cells has been studied by means of radioactive tracers. The initial distribution of the tracers—²⁴Na for the bath and¹⁹⁸Au for the metal phase-indicates a fast circulating movement with vortices at the ends in both phases. Circulation rates up to 100 cm per sec were observed, and an average value seemed to be 10 cm per sec. The implications of the convection on the mechanism of the secondary reactions, the dissolution of alumina in the bath electrolyte and the distribution of carbon particles in the cell are discussed.     

Cyanide inhibitors for the carbon cathode materials in aluminum reduction cells

During the operation of aluminum reduction cells, sodium cyanide is formed in the carbon cathode materials that have been subjected to sodium diffusion followed by molten bath infil-tration. Effects of the penetrating bath composition on the cyanide formation in these materials were investigated and emphasis was put on the elaboration of cyanide inhibitors. Aluminum fluoride up to 15 wt pct in the monolithic mix appeared to be a good candidate.     

Recent studies of convection in commercial aluminum reduction cells

Convection rates and patterns in the bath electrolyte and the cathode metal of 150 kA prebaked anode aluminum reduction cells have been studied by means of radioactive tracers. Gamma radiation probes have been used for a continuousin situ determination of the radiotracer activity in the bath and liquid metal. The measurements are compared with predicted convection patterns from model magnetodynamic calculations for both magnetically compensated and uncompensated reduction cells. The measurements give evidence of a strong coupling between the convection currents in the metal and bath phases. The recorded activity vs time data further allow an estimation of the degree of turbulence in the reduction cells. From these investigations attempts are made to correlate data from the convection studies with current efficiency, as determined by the method of isotope dilution. The same method has also been used to determine liquid bath volume and the melting-out of solid bath electrolyte during periods with anode effect.     

Thermal and grain-structure simulation in a land-based turbine blade directionally solidified with the liquid metal cooling process

The thermal field and the grain structure of a cored superalloy turbine blade, which has been directionally solidified with the liquid metal cooling (LMC) process, has been simulated in three dimensions using a cellular automaton (CA) coupled with finite-element (CAFE) model. The cooling induced by the liquid aluminum bath has been replaced by a heat-transfer coefficient, whose temperature- and time-dependence has been adjusted on the basis of natural convection simulations and dimensionless analyses. The simulated grain structure and crystallographic texture have been compared with the microstructure, and the electron back-scattered diffraction (EBSD) results were obtained for a real blade. In both the experiment and the simulation, it has been found that the grains do not exhibit a well-defined <001> texture, even near the top of the blade, mainly as a result of a concave liquidus surface. In order to improve the texture and decrease the number of stray crystals, the LMC process was then optimized by changing several parameters. The baffle geometry, the liquid bath level, and the thermal conductivity of the ceramic mold were found to be the dominant parameters. Using the optimized design, the effect of the withdrawal rate on the resulting grain structure was investigated.     

Theory Study of AlCl Disproportionation Reaction Mechanism on Al (110) Surface

The surface disproportionation reaction mechanism of aluminum subchloride on aluminum (110) surfaces has been investigated using the plane-wave density functional theory (DFT). Three possible reaction mechanisms of AlCl disproportionation reaction on aluminum (110) surfaces have been taken into account; the reactants and products structures have been optimized, transition states have been confirmed, and activation energy has been calculated. The adsorption energy of reactants and the desorption energy of products also have been calculated. All of these calculations have been employed to confirm the reaction mechanism and the rate-determining step of AlCl disproportionation reaction on aluminum (110) surfaces.