320kA预焙铝电解槽电磁场分布计算与优化

利用ANSYS电磁场有限元法,建立了320 kA预焙铝电解槽三维电磁场有限元模型,计算了铝电解槽内的电场分布及磁场分布,计算结果与实测结果相吻合,验证了该模型的正确性.在此基础上提出了一种新型电解槽结构,并应用参数化设计语言(APDL)建立该结构的电磁场计算模型,以磁场为目标对该结构进行了整体优化.最终优化后电磁场分布表明:该结构铝电解槽能减小铝液层水平电流,磁场分布对称性好,有利于改善槽内铝液的流动状态,具备较大的节能潜力.     

铝电解槽熔体中电流分布的数值计算

在电解槽三维电位场计算的基础上,对电解槽在不同工艺条件下及不同结构时的电流场进行了数值计算:1)伸腿长度为零的理想情况;2)伸腿伸至阳极底部;3)不同铝水平及换极;4)泄流式电解槽.通过分析发现,铝液中y 向电流密度沿阴极长度方向表现出先增后降的趋势,Jy的幅值随铝液层面降低有所增加.在伸腿伸至阳极底部时,在槽边部会出现较大的逆向电流,伸腿越长,逆向水平电流越大.铝液层面中垂直电流密度沿阴极碳块长度方向自里向外呈现增加趋势,且铝液层面越低,电流密度变化梯度越大.铝液中x向电流可以忽略,且随铝水平变化较小.泄流式电解槽熔体中存在较大的电流密度集中现象,炉底压降相对较大.     

不同开槽阳极铝电解槽的节能性研究

基于有限体积方法,建立三维传统阳极、纵向开槽和横向开槽阳极铝电解槽非稳态数学模型,采用磁动力流体模型(MHD)中电势法计算电磁场,把电磁力作为动量方程的源项,通过流体体积函数(VOF)法追踪电解质-铝液界面的波动,用离散相模型(DPM)追踪气泡的运动路径.对比分析传统阳极、纵向开槽和横向开槽阳极铝电解槽中电解质-铝液界面波动和气泡分布情况.结果表明,纵向开槽阳极下电解质-铝液界面波动幅度小于横向开槽阳极下的电解质-铝液界面波动幅度,且都小于传统阳极下电解质-铝液界面波动幅度.纵向开槽阳极底部的气体体积分数最小.     

浅析160 kA预焙电解槽阳极效应系数控制

通过对贵铝二期160kA预焙电解槽阳极效碰系数的分析与讨论，发现AE系数与Al2O3浓度，计算机控制加工制度、原材料质量以及人工操作控制等因素有关。降低AE系数，有利于提高经济技术指标。提出了今后效应系数的控制发展方向。     

Loss of current efficiency in aluminum electrolysis cells

Consideration of the mechanism of loss of current efficiency (CE) leads to a form of equation which is simple, likely to give reasonable extrapolation beyond the range where experimental data are available, and convenient for responding to practical questions. With coefficients generated from plant experiments (performed by others), the equation is log (pct loss of efficiency) = 0.0095 (superheat) -−0.019 (pct A1F₂) − 0.060 (pct LiF) + const where superheat is the difference (in °C) between cell temperature and the pseudo-binary eutectic temperature with A1₂O₃, and pct A1F₃ is excess A1F₃. The coefficient for CaF₂ is zero. The constant is characteristic of the cell design. The question of reconciling the values of the coefficients with literature data on the solubility of Al in cryolite melts and current theories of loss of efficiency is discussed. Formerly Principal Scientist, Kingston Laboratory, Alcan International Ltd., Kingston, ON K7L 5L9, Canada, is retired.     

铝电解槽阳极气泡行为研究

利用透明槽研究铝电解槽阳极气体行为.研究表明：阳极气体的生成是一个连续的过程,阳极侧部生成的气泡比阳极底部生成的气泡小.正对阴极的阳极表面生产的气泡比其它阳极部位上生成的气泡小,这是一个明显的现象.而且,正对阴极的阳极表面生成的气泡不会汇集成大气泡,这和其它阳极部位生成的气泡有很大的差异.阳极底部生成的气泡全部从阴阳极中间的电解质移动溢出电解质.阳极气泡的大小影响槽电压,气泡直径增大3 mm,槽电压增加0.21 V.同时,电流密度为0.5 A/cm2底部阳极气体离开阳极时槽电压的变化为0.16 V.电流密度为0.3 A/cm2,底部阳极气体离开阳极时槽电压的变化为0.12 V.     

预焙阳极铝电解节能降耗途径探讨

本文以85kA预焙槽为例，从铝电解槽生产成本的构成着眼，探讨了从优化工艺技术条件、强化电流强度、降低原材料消耗、燃料及动力消耗、制造费用等方面降低预焙铝电解生产成本的途径，电流强度的强化、优化工艺技术条件、阳极加高等技术的成功应用，提高了电流效率、降低了直流电耗，节能效果显著，创造了良好的经济效益。     

Monitoring of the quality of a soderberg anode for aluminum electrolyzer with the upper current lead

By sampling the cores from the Soderberg anodes of switched-off aluminum electrolyzers, the distribution of the physical properties over the anode height, including during a variation in temperature, is studied. An analysis is given for the dynamics of the variation in the quality of anodes from 1993 to 2006. It is shown that the physical properties of the Soderberg anode approach the requirements made for burnt anodes.     

Effect of baking temperature and anode current density on anode carbon consumption

The electrolytic anode carbon consumption (CC) was studied as a function of anode baking temperature (BT) and anode current density in a closed laboratory cell, where the anode gas was absorbed and also monitored on a CO/CO₂ analyzer. The CC referred to Faraday’s law was determined from the weight loss of the anode, the carbon gasification (CG) from the amount of absorbed anode gas, and the formation of carbon dust (CD) by the difference. The CC decreased by about 9 pct per 100 °C increase in BT, and it increased with decreasing anode current density, particularly at low current densities. The CG and CD showed similar trends. The excess CG, which was attributed to the Boudouard reaction (CO₂ + C = 2CO), showed a relative decrease with increasing current density, although the overall rate of the reaction increased.     

The influence of the atmosphere on the sintering of aluminum

Alloys of Al, Al-0.15Mg, and Al-12Sn made using air atomized aluminum powder and pressed to green densities of 75 to 98 pct were sintered under argon or nitrogen. Sintering in argon is only effective at high green densities when magnesium is present. In contrast, highly porous aluminum can be sintered in nitrogen without the need for magnesium. The oxygen concentration in the gas is reduced by the aluminum through a self-gettering process. The outer layers of the porous powder compact serve as a getter for the inner layers such that the oxygen partial pressure is reduced deep within the pore network. Aluminum nitride then forms, either by direct reaction with the metal or by reduction of the oxide layer, and sintering follows.     

Determination of metal inventory and current efficiency in commercial aluminum reduction cells

A method for the determination of the metal inventory in commercial aluminum reduction cells, based on radioisotope dilution, has been developed, employing a¹⁹⁸Au tracer. By taking a large number of samples from the cells, the current efficiency is evaluated from the slope of the cumulative metal inventory vs time data. The method allows a determination of the current efficiency over a period of 2 to 3 days with a relative precision of approximately 1 pct. The paper gives a thorough discussion of the sources of error inherent in the procedure suggested. Formerly Research Associate at the same University.     

预焙阳极质量对铝电解生产的影响

论述预焙阳极质量对铝电解生产的影响，提出减少阳极炭渣的有效方法．     

The diet and gut microflora influence the distribution of enteroendocrine cells in the rat intestine

Several functions of the gut are locally influenced by peptides and biogenic amines released from enteroendocrine cells. The aim of the present study was to assess whether the luminal stimulus of diet or microbial flora or diet-microbial interactions have an influence on the distribution of enteroendocrine cells along the crypt-surface axes of the small and large intestine. The effects of diet and indigenous flora were investigated by comparing the numbers of argyrophil and serotonin immunoreactive cells in the jejunum and colon of germ free and conventional rats fed either a purified diet containing fine ingredients or a commercial diet containing crude fibre of cereal origin. The effect of human flora were analysed in germ-free rats inoculated with human faecal organisms. 1. Feeding the commercial diet reduced the number of argyrophil endocrine cells in the jejunum and serotonin immunoreactive cells in the colon of germ-free animals but increased the serotonin immunoreactive cells in the colon of conventional animals. 2. The rat flora increased the serotonin immunoreactive cells in the colon of animals fed a commercial diet and decreased in those fed a purified diet. 3. Inoculation of human flora increased the numbers of serotonin immunoreactive cells both in the jejunum and colon. The results provide evidence that the dietary changes and diet-microbial interactions can affect the regional number of enteroendocrine cells.     

300kA大型预焙电解槽电流效率影响因素的研究

分析了大型预焙电解槽中电解质温度与电流效率、直流电耗的关系,研究发现电解槽在目标电解温度下可获得最佳的电流效率和最低的直流电耗,高于或低于目标电解温度都将影响生产效率。同时分析了电解质分子比、氧化铝浓度、添加剂以及铝水平、电解质水平等因素对电解质温度及电流效率的影响,并对工艺因素的最佳值进行了探讨。     

The influence of shape on the stresses in model abdominal aortic aneurysms

Presence of a small abdominal aortic aneurysm (AAA) often presents a difficult clinical dilemma--a reparative operation with its inherent risks versus monitoring the growth of the aneurysm, with the accompanying risk of rupture. The risk of rupture is conventionally believed to be a function of the AAA bulge diameter. In this work, we hypothesized that the risk of rupture depends on AAA shape. Because rupture is inevitably linked to stress, membrane theory was used to predict the stresses in the walls of an idealized AAA, using a model which was axisymmetric and fusiform, with the ends merged into straight opened-ended tubes. When the stresses for many different shapes of model AAAs were examined, a number of conclusions became evident: (i) maximum hoop stress typically exceeded maximum meridional stress by a factor of 2 to 3 (ii) the shape of an AAA had a small effect on the meridional stresses and a rather dramatic effect on the hoop stresses, (iii) maximum stress typically occurred near the inflection point of a curve drawn coincident with the AAA wall, and (iv) the maximum stress was a function--not of the bulge diameter---but of the curvatures (i.e. shape) of the AAA wall. This last result suggested that rupture probability should be based on wall curvatures, not on AAA bulge diameter. Because curvatures are not much harder to measure than bulge diameter, this concept may be useful in a clinical setting in order to improve prediction of the likelihood of AAA rupture.     

The influence of load on the lifetime distribution

This paper derives lifetime distributions for components that fail due to overloading. We introduce the notion of energy similarity. This makes it possible to use knowledge about how components behave under different loads in order to establish a probability model. To obtain parametric families, we consider two physically distinct cases: (1) components that function individually and (2) components that function as part of a system. The former leads to univariate and the latter to multivariate models. The results are particularly useful when little or no data is available.     

Simulating the process of carbon anode baking used in the aluminum industry

A simulation scheme for the baking process of carbon anodes as practiced in the aluminum industry is presented. Despite the very complex nature of the process, the proposed scheme is simple enough to be readily implemented on the computer yet takes into account all the important aspects of anode baking: the infiltration of air, the control of depression in the flues, the release and burning of volatiles, and the heat loss to the atmosphere and to the furnace foundation. Emphasis in this paper is laid on the design of the simulation algorithm, more than on the detailed arguments behind the development of the model equations. Two interesting features are worth mentioning. First, the modular structure adopted for the algorithm helps increase its clarity. Second, in executing a simulation run on the computer, the analyst actually “adjusts” the depression in the flues and the fuel flow at the burners the same way a human operator does in the real process. Test runs are made, first to reproduce the existing operating conditions, then to study the effects of various parameter changes on the process. Most of the time this cannot be done on the real facility due to the costs and risks involved. Results show that the proposed model is a reliable tool for process evaluation and improvement.     

铝电解过程中阳极气泡对槽电压波动的影响

铝电解过程中阳极底部产生气泡,气泡排放会引起电解槽的槽电压波动.本文采用透明槽进行铝电解实验,在阳极上施加恒定电流电解,电流密度为0.7 A/cm2,观察气泡行为和气泡对槽电压影响,研究了水平阳极和阳极倾斜角为2°的条件下得到的气泡在阳极底部的形成长大过程,分析了气泡对槽电压的影响.结果表明:槽电压-时间曲线呈锯齿形状...