磁场对铝电解高温熔盐电解质相变温度的影响

采用“动态法”测温技术及特制的热电偶探头,对铝电解现场有磁场影响下的铝电解熔盐电解质的相变过程进行了直接测定,并与在实验室中测定的没有磁场影响下的铝电解熔盐电解质相变过程的测定结果进行了对比。结果表明：300kA预焙铝电解槽中,烟道端与出铝端的电解质在磁场强度为13.39高斯和14.75高斯下的初晶点温度分别为955.4℃和950.7℃,而没有磁场的初晶点941.59℃和943.41℃。磁场确实会对铝电解熔盐电解质的初晶点温度产生影响。     

面向铝电解槽的变论域模糊专家系统

在铝电解过程中有很多参数影响电流效率和电解槽的稳定性。AlF3添加量和出铝量是2个影响铝电解生产经济效益的重要因素。模糊逻辑提供一种合适的机制来描述铝电解过程参数与电流效率之间的关系。在铝电解过程中,采用基于Mamdani模糊推理过程的模糊专家系统调整AlF3添加量和出铝量。系统应用一种新的变论域方法,解决不同电解槽具有不同参数论域的问题,并将系统应用于某电解厂的300kA铝电解槽中。实验结果表明,电解质温度稳定在945℃～955℃,电流效率达到93.5%,吨铝直流电耗为13000kW·h。     

160 kA预焙铝电解槽"四低一高"电解工艺技术条件的选择

介绍了智能模糊控制技术在160 kA大型预焙铝电解槽应用后,铝电解采用"四低一高"的工艺技术条件,即低分子比、低电解温度、低氧化铝浓度、低阳极效应系数、高极距(或称高电压)和人工作业工序的方法.此方法即标准化作业可明显提高电流效率、降低电耗.     

伊川300kA电解槽模糊控制技术开发与研究

本文通过对300kA级电解槽模糊控制技术的实践应用，特别是在氧化铝浓度和效应控制方面运用良好．电解槽运行平稳、高效，实践证明，伊铝300kA系列电解槽生产指标已达到国际先进水平。     

铝电解槽控机节能实践

晋信铝厂60kA自焙槽强化改造为75kA中间点式下料予焙槽．通过采用铝电解槽智能模糊控制系统，电流效率提高，电耗大幅度下降。本文简要介绍该系统的基本控制原理和节能效果。     

预焙铝电解槽电流效率软测量模型研究初探

针对铝电解槽电流效率难以在线测量的特点,提出了基于模糊C-均值聚类的多神经网络电流效率软测量模型。通过采集某厂200kA预焙电解槽的槽电压、电解质温度、分子比、电解质水平、铝水平、氟化铝投入量等工艺参数的历史数据作为样本;使用自标准化方法对样本数据进行预处理;再将处理后的数据用模糊C方法进行聚类得到优化样本;利用多神经网络对这些样本进行训练,得到电流效率的软测量模型。应用该模型对200kA预焙铝电解槽电流效率进行在线测量发现,测量值与实际值对比,测量误差不超过4.83%。     

基于模糊变系数PID算法的注塑机料筒温度控制

注塑机料筒温度是注塑工艺的重要参数,对料筒温度进行有效地控制是保证塑料制品成型质量的重要环节.料筒温度系统是一个多变量、离散、间歇工作、大滞后、非线性、强耦合且需要人工参与的复杂系统.本文采用模糊变系数PID控制,用模糊规则对模糊变系数PID算法中的系数进行在线修正.结果表明该算法提高了温度控制系统的鲁棒性,超调减小,...     

基于Web的工业铝电解槽温度分析系统

开发了基于Web的工业铝电解槽温度分析,以Flash图表直观展示电解槽槽壳温度、电解温度的分布曲线和历史变化曲线,用数据透视表和透视图实现温度数据的多维度、多层次分析.该系统在200kA电解系列的应用表明,其运行可靠,界面操作简单,有助于及时把握电解槽的运行状态,发现槽的破损隐患,为企业创造效益.     

玻璃熔窑温度微机监控系统

介绍了基于工控机的玻璃熔窑温度控制系统。该控制系统采用了基于模糊神经元网络的模型参考自适应控制的结构。该控制系统操作界面和系统控制程序采用VC 6．0编制,软件采用标准化模块设计。文章同时也介绍了自适应模糊神经元网络控制系统的设计过程,以及该控制系统的控制原理。最后通过Matlab语言编制仿真软件对该系统进行了仿真。     

铝电解槽能量平衡稳定控制技术研究及其应用

影响电解槽能量平衡的主要因素是槽电压和氟化铝添加量.本文通过对槽电压、氟化铝添加量和氧化铝添加情况对能量平衡的研究,在其它工艺技术条件保持不变的情况下,得出了铝电解槽能量平衡控制模型.并且,在180kA铝电解槽上实现了能量平衡的稳定控制,电解技术指标也有所提高,达到了节能降耗的目的.     

LOW TEMPERATURE ALUMINUM FLOATING ELECTROLYSIS IN HEAVY ELECTROLYTE Na_3AlF_6-AlF_3-BaC1_2-NaCl BATH SYSTEM

1. IntroductionSince the Hall--Heroult process was invented one hundred years ago, it has been the onlyaluminum production method in the w..ldll]. The process has many weak points, such aslow unit productivity; low energy utilization, less than 50%; high electrolytic temperature,usually at 950ap; high consumption of carbon material; serious environmental pollutionand so on. It is well known that the melting point of aluminum is 660ap, therefore, aluminum electrolysis at the range of 700--800C…     

预焙铝电解槽阳极底部开排气沟对电解质流场的影响

对预焙铝电解槽阳极底部开排气沟时周围电解质流场进行计算,发现部分阳极气体可以通过排气沟向外排放,减少气泡在阳极底部停留时间和阳极底掌气泡覆盖率,从而有利于降低极间电阻压降和阳极效应系数,减少电解能耗;另一方面气体带动电解质进入排气沟,然后进入电解槽侧部通道,扩大了电解质循环通道,促进了阳极周围电解质流动和槽内的传质传热,有利于保持电解正常进行,相比之下排气沟为通沟时较非通沟更有利于保持电解质流动稳定;同时由于排气沟促进了阳极气体排放,使铝液与阳极气体发生“二次反应”(即电解还原的铝卷入电解质中被阳极气体重新氧化)的机会减少,有利于提高铝电解电流效率。     

LOW TEMPERATURE ALUMINUM ELECTROLYSIS IN NaF-AlF3-BaF2-CaF2 BATH SYSTEM

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一种含氟化镁电解质体系的温度、密度和导电度论证

本文对一种在生产中使用的含镁铝电解质体系的温度、密度、导电度利用经验公式进行了论证。通过论证得出如能通过技术手段和管理手段对电解质中各成份含量进行精细控制，电解生产可以在较低温度下高效运行；该电解质体系和铝液的密度差在一些情况下较小，生产中注意提前调控；该电解质体系和低分子比高氟化钙电解质体系的导电度相当。     

Investigation of the Ledge Structure in Aluminum Smelting Cells

In aluminum smelting cells, ledges freeze on to cell walls from the cryolitic bath when the temperature drops below the bath liquidus point. Modern cell design and control cause a suitable ledge profile to form and be maintained, in order to protect the cell walls from corrosive liquids (molten salts and Al metal) and ensure efficient current distribution and cell heat balance. During cell operation, a significant ledge, freezing and melting does occur following heat balance changes due to batch operations. The ledge formation mechanism has been studied at the laboratory scale in our previous work. It shows a linkage between the rate and directional nature of ledge growth and its structure as affected through a superheat change. An open ledge structure can dominate the laboratory ledge material growth or melt it out quickly when the superheat either decreases or increases, respectively. This paper begins the investigation of industrial ledge samples, in terms of structure and composition, primarily to identify whether the same ledge formation mechanism exists in industrial cells. In this study, as expected, the industrial ledge shows more complexity than the laboratory ledge; the open structure is different compared to the laboratory ledge due to the inclusion of carbon dust, a large thermal gradient across the ledge, and sufficient aging of the ledge in the cell. The comparison between the laboratory ledge and the industrial ledge has provided insight into the ledge growth mechanism in aluminum smelting cells.

     

铝电解槽电压平衡测试与分析

通过对5个电解槽电平衡的测试,比较了各厂阳极压降、阴极压降、电解质压降,分析了某些厂局部压降过高的原因。根据测试结果,指出了阳极压降与阳极电流密度的关系,说明了阴极压降不能与阴极材质对应的缘由,阐述了单位电解质压降的影响因素,为降低电解槽工作电压提供了理论依据。     

Employing a new bath- and liquidus temperature sensor for molten salts

In this article, a newly developed sensor that measures bath and liquidus temperatures is described. The accuracy and reproducibility of the sensor are discussed, and the sensor’s output is compared with results obtained using other techniques. A series of measurements in point-feed and center-worked cells are given. Finally, the evolution of bath and liquidus temperature is shown with respect to feed strategies. P. Verstreken earned his Met.Eng. in metallurgy at the University of Louvain, Belgium, in 1978. He is currently senior manager in the aluminum business area at Heraeus Electro-Nite. Mr. Verstreken is also a member of TMS.     

A Nonlinear Shallow-Water Model Combined with Gas Bubble Effect for Melt Flows and Interface Instability in Aluminum Reduction Cells

A nonlinear shallow-water model combined with the effect of anode gas bubbles was derived for the melt flows and interface instability in aluminum reduction cells. Both the electromagnetic forces and the drag forces between the bath and gas bubbles, as the main driven forces for the melt flows, were taken into account in this model. A comparative numerical study was carried out using both the model considering the bubble and the model without considering the bubble. The results show the effect of the bubble cannot be neglected in a fluid dynamics analysis for the aluminum reduction cell. The bath flow, induced by the motion of bubbles, presents a series of small eddies rather than large eddies as the metal flow pattern shows. The horizontal drag forces between the bath and the bubbles in the bath layer enlarge the deformation of the metal–bath interface, to some extent, but have a positive influence on stabilizing the metal–bath interface perturbations.     

The multivariable model-based control of the non-alumina electrolyte variables in aluminum smelting cells

This paper investigates the application of multivariable model-based control to improve the regulatory control of electrolyte temperature, aluminum fluoride concentration, liquidus temperature, superheat, and electrolyte height. Also examined are therappropriateness of different control structures and the possible inclusion of recently developed sensors for alumina concentration and individual cell duct flowrate, temperature, and heat loss. For the smelter in this study, the maximum improvement possible with a multivariable model-based controller is predicted to be 30–40% reduction in standard deviation in electrolyte temperature, aluminum fluoride concentration, liquidus temperature, and superheat, and around half this for electrolyte height. Three control structures were found to be appropriate; all are different than the existing control structure, which was found to be suboptimal. Linear Quadratic Gaussian controllers were designed for each control structure and their predicted performance compared. Comalco Research.     

铝电解槽阳极系列电阻随工作天数的变化规律研究

研究阳极电阻变化规律,找出在现有的技术条件下降低阳极压降的途径,对降低槽电压、降低能耗有重要意义。利用有限元分析软件ANSYS建立模型分析一个换极周期内阳极温度场与阳极系列电阻的变化规律,仿真结果表明:随着阳极的消耗,阳极顶部温度逐渐增加,阳极系列电阻逐渐变小,在电解温度一定的情况下,保持较高的电解质水平、较厚的覆盖层,有助于提高阳极温度,降低阳极系列电阻与压降。