2~#闪速炉水套及冷却水管在线化学清洗

针对熔炼车间二系统2#闪速炉内铜水套和炉体周围冷却水管道腐蚀结垢严重的现象,提出了有效的除垢方法,保证了2#闪速炉的正常运转。     

攀钢镀锌机组连续退火炉在线控制系统

针对攀钢现有的自动化控制模式,开发出一种在线优化二级控制系统（L2）。介绍了L2系统的组成及其功能。系统在线投入后运行稳定,各项生产技术指标得到了系统的优化,极大地减少了生产过程中生产参数的人工输入。     

高炉炉缸凝壳和残衬双轮廓内型的诊断模型

高炉炉缸内衬侵蚀和凝壳的形成决定了炉缸的寿命.为及时掌握高炉炉缸凝壳和残衬双轮廓内型状况,进而及时制定合理应对措施,结合数值传热学、优化导热系数法以及Levenberg-Marquardt法、拟牛顿法和梯度法3种优化算法,建立了高炉炉缸凝壳和残衬双轮廓内型诊断模型.重点阐述了模型的构建思路和过程,构造了象脚状侵蚀样本对...     

Influence of the reducing-gas distribution in the tuyere belt on the buildup in midrex furnaces

The influence of the reducing-gas distribution in Midrex furnaces is investigated. The temperature of the tuyere belt in the furnace lining is studied experimentally, and blockage of the tuyeres by buildup is analyzed. The tuyeres are mainly blocked on account of the nonuniform reducing-gas distribution, which is associated with the temperature gradient over the length of the tuyere belt.     

Understanding the bottom buildup in an electric copper smelting furnace by thermodynamic calculations

Thermodynamic calculations were used to investigate the liquidus temperature of the slag and the possible influence on the buildup formation in an electric copper smelting furnace. The impact of parameters such as Fe/SiO₂ ratio, partial pressure of oxygen and the content of the oxides ZnO, Al₂O₃ and Cr₂O₃ in the slag were investigated with respect to the liquidus temperature of the slag. Results show that the chromium content in the slag has the greatest impact on the liquidus temperature and on the formation of solid particles. The characterisation of the buildup done earlier showed that spinel phases were among the dominating phases. This is supported by the thermodynamic calculations in the present paper, where the chromite solid solution was found to be the primary precipitation phase.     

Ladle heating of hot metal on discharge from the blast furnace

The heating of hot metal in the ladle on discharge from the blast furnace is considered. In this case, the heating is due to aluminum flux, which is an exothermal slag-forming powder made from slag wastes obtained in secondary aluminum production. The proposed technology reduces the slag-metal buildup and increases the life of the refractory lining to 500 filling cycles. Effective heat insulation of the hot-metal surface reduces the heat losses to 15–20°C prior to mixer delivery. The slag runoff is reduced by 25–45% (rel.).     

Mathematical analysis of reactions in metal oxide/carbon mixtures

A mathematical study has been made of the rates of reactions in metal oxide/carbon mixtures. The rate equations derived take into account the rate control by carbon-CO₂ oxidation and by diffusive and viscous flow of the reaction products, CO₂ and CO, through the packed bed where a pressure gradient exists. As the thickness of the powder mixture increases, the pressure buildup during reduction increases. If the furnace atmosphere is a neutral gas, the rate of reduction of metal oxides by carbon decreases, because of the dilution of CO₂ in the interparticle pores of the bed by back diffusion of the furnace atmosphere.     

A Model to Simulate Titanium Behavior in the Iron Blast Furnace Hearth

The erosion of hearth refractory is a major limitation to the campaign life of a blast furnace. Titanium from titania addition in the burden or tuyere injection can react with carbon and nitrogen in molten pig iron to form titanium carbonitride, giving the so-called titanium-rich scaffold or buildup on the hearth surface, to protect the hearth from subsequent erosion. In the current article, a mathematical model based on computational fluid dynamics is proposed to simulate the behavior of solid particles in the liquid iron. The model considers the fluid/solid particle flow through a packed bed, conjugated heat transfer, species transport, and thermodynamic of key chemical reactions. A region of high solid concentration is predicted at the hearth bottom surface. Regions of solid formation and dissolution can be identified, which depend on the local temperature and chemical equilibrium. The sensitivity to the key model parameters for the solid phase is analyzed. The model provides an insight into the fundamental mechanism of solid particle formation, and it may form a basic model for subsequent development to study the formation of titanium scaffold in the blast furnace hearth.     

Minimisation of calcium additions to low carbon steel grades

Abstract

This investigation aimed to determine the in plant feasibility of decreasing, to an amount close to the minimum literature value, the calcium addition to liquid steel for prevention of alumina buildup during continuous casting. Six plant trials were carried out at calcium additions of 0·14 kg/t of steel (reduced from the original 0·19 kg/t), added to the second ladle of a two or three ladle sequence. Total oxygen samples were taken at the ladle furnace and tundish to determine total oxygen and nitrogen contents of the steel. The total oxygen content at the ladle furnace varied between 19 and 26 ppm, with a slight degree of reoxidation between the ladle furnace and the caster. Alumina clogging was successfully prevented by the addition of 0·14 kg calcium/t of steel during the first five trials. During the sixth trial the submerged entry nozzle (SEN) failed and, although the stopper behaved as if clogging occurred, this behaviour was caused by the poor perfomance of the SEN rather than actual clogging. Microanalysis of inclusions in steel samples revealed a distribution in degrees of modification between different inclusions, and the formation of a substantial amount of CaS (which is taken to indicate overmodification, based on equilibrium calculations). However, the CaS is mostly associated with at least partly liquefied oxide inclusions, which is likely to reduce the potential clogging effect of solid CaS.     

Proactive interference and the dynamics of free recall.

Proactive interference (PI) has long been recognized as a major cause of forgetting. Two experiments were conducted that offer another look at the subject by providing a detailed analysis of recall latency distributions during the buildup of and release from PI. These functions were accurately characterized by the convolution of the normal and exponential distributions (viz., the ex-Gaussian), which previously has been shown to describe recognition latency distributions. Further, the fits revealed that the increase in recall latency associated with the buildup of PI results from a slowing of the exponential retrieval stage only. The same result was found even when a short retention interval was used (and recall probability remained constant). These findings suggest that free-recall latency may be a sensitive index of the increased search set size that has often been assumed to accompany the buildup of PI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Buildup in mixers when processing vanadium hot metal

Samples of the buildup in a mixer processing low-silica vanadium hot metal undergo chemical and X-ray microspectral analysis. The buildup consists of high-temperature spinelide, ilmenite, magnetite, and other phases. The mechanism by which the buildup forms is established, and measures for its prevention are developed.     

Estimating Pollutant Mass Accumulation on Highways during Dry Periods

For determining the accumulated pollutant mass on highways, two years of monitoring data were used from eight highway sites in southern California. Buildup over antecedent dry days was calculated from mass washed off from the following storm and retained pollutant mass. Mass accumulation rates were determined for total suspended solids (TSS), chemical oxygen demand (COD), oil and grease, total Kjeldahl nitrogen, and total phosphorus, and are reported in g/m2-day. A revised buildup model is proposed using an alternative modeling approach to describe buildup during dry days between storms. The result shows that, between 1 and 10 antecedent dry days, the pollutant mass buildup rates are determined to be 0.544?g/m2-day for TSS, 0.114?g/m2-day for COD, and 0.0113?g/m2-day for oil and grease. Buildup rates decline in subsequent periods rates decreased by 79% for TSS, 78% for COD, and 61% less for oil and grease in the following 10–70?day period.     

Echo suppression and discrimination suppression aspects of the precedence effect

The precedence effect is a phenomenon that may occur when a sound from one direction (the lead) is followed within a few milliseconds by the same or a similar sound from another direction (the lag, or the echo). Typically, the lag sound is not heard as a separate event, and changes in the lag sound's direction cannot be discriminated. The hypothesis is proposed in this study that these two aspects of precedence (echo suppression and discrimination suppression) are at least partially independent phenomena. Two experiments were conducted in which pairs of noise bursts were presented to subjects from two loudspeakers in the horizontal plane to simulate a lead sound and a lag sound (the echo). Echo suppression threshold was measured as the minimum echo delay at which subjects reported hearing two sounds rather than one sound; discrimination suppression threshold was measured as the minimum echo delay at which subjects could reliably discriminate between two positions of the echo. In Experiment 1, it was found that echo suppression threshold was the same as discrimination suppression threshold when measured with a single burst pair (average 5.4 msec). However, when measured after presentation of a train of burst pairs (a condition that may produce "buildup of suppression"), discrimination suppression threshold increased to 10.4 msec, while echo suppression threshold increased to 26.4 msec. The greater buildup of echo suppression than of discrimination suppression indicates that the two phenomena are distinct under buildup conditions and may be the reflection of different underlying mechanisms. Experiment 2 investigated the effect of the directional properties of the lead and lag sounds on discrimination suppression and echo suppression. There was no consistent effect of the spatial separation between lead and lag sources on discrimination suppression or echo suppression, nor was there any consistent difference between the two types of thresholds (overall average threshold was 5.9 msec). The negative result in Experiment 2 may have been due to the measurements being obtained only for single-stimulus conditions and not for buildup conditions that may involve more central processing by the auditory system.     

侧吹炉的现状与展望

阐述了目前侧吹炉的炉体结构、主要设计参数、运行操作以及存在的主要问题。提出了为进一步提升侧吹炉在投资及运行成本方面的优势,侧吹炉需要朝着优化炉体结构、大幅度提高产能、大幅度提高炉体寿命、操作机械化以及运行智能化等方面发展。论述了处理能力由现在的300 kt/a大幅度提高到600 kt/a的方法以及炉体寿命由现在的2～3年大幅度提高到闪速炉熔炼炉炉体寿命的8～9年而采取的措施。     

Planar imaging quantification using 3D attenuation correction data and Monte Carlo simulated buildup factors

A new method to correct for attenuation and the buildup of scatter in planar imaging quantification is presented. The method is based on the combined use of 3D density information provided by computed tomography to correct for attenuation and the application of Monte Carlo simulated buildup factors to correct for buildup in the projection pixels. CT and nuclear medicine images were obtained for a purpose-built nonhomogeneous phantom that models the human anatomy in the thoracic and abdominal regions. The CT transverse slices of the phantom were converted to a set of consecutive density maps. An algorithm was developed that projects the 3D information contained in the set of density maps to create opposing pairs of accurate 2D correction maps that were subsequently applied to planar images acquired from a dual-head gamma camera. A comparison of results obtained by the new method and the geometric mean approach based on published techniques is presented for some of the source arrangements used. Excellent results were obtained for various source-phantom configurations used to evaluate the method. Activity quantification of a line source at most locations in the nonhomogeneous phantom produced errors of less than 2%. Additionally, knowledge of the actual source depth is not required for accurate activity quantification. Quantification of volume sources placed in foam, Perspex and aluminium produced errors of less than 7% for the abdominal and thoracic configurations of the phantom.     

国丰1780m~3高炉烧结-高炉系统碱金属平衡的研究

为了弄清国丰1 780 m3高炉中碱金属的来源与去向,降低高炉碱负荷以减轻碱金属对高炉的危害,对国丰1 780 m3高炉以及为其供给烧结矿的230 m2烧结机进行了碱金属的平衡研究。结果表明:国丰烧结过程中的K主要由白灰带入,Na主要由巴西粗矿带入;1 780 m3高炉吨铁碱负荷为5 047 g,进入高炉的碱金属主要来源于烧结矿;高炉中的K、Na主要通过炉渣排出。     

Decreased gas consumption of a fluidized bed furnace

The feasibility of utilizing a closed circulatory system to generate gases for a fluidized bed furnace was investigated with the primary concentrations of both economizing on the raw materials used for producing furnace atmospheres and decreasing the air pollution caused by exhaust gases. Air humidified with water vapor was first introduced into a charcoal furnace for causing a reaction with hot charcoal to form a carburizing atmosphere. This atmosphere was then introduced into a fluidized bed furnace to carburize steels. The exhaust gases from the fluidized bed furnace were recycled by repassing them through the hot charcoal layer in the charcoal furnace with a gas pump. The charcoal furnace and the fluidized bed furnace formed a closed circulatory system during the carburization of steels. Experiments were performed with various parameters of this system, including content of water vapor in the humid air, temperature of the charcoal, rate of recirculation of the atmosphere,etc. The effect of each parameter on the carburizing behavior in the fluidized bed furnace was investigated on the basis of the rate of carburization and the carbon potential of the atmosphere. The feasibility of applying this system to a fluidized bed furnace was assessed from the aspects of the fluidization of A1₂O₃ powder, the result of carburizing steel, and the rate of consumption of charcoal. The closed system employed in generating atmosphere was demonstrated by the experimental results to have enabled the fluidized bed furnace to operate normally and to have significantly decreased both the consumption rate of charcoal and the environmental pollution.     

国内外钢包的粘渣及其对策

阐述了国内外钢外的粘渣状况及减轻粘渣的措施，并通过分析概括，提出了钢包粘渣的主要原因和减轻粘渣的对策。     

链条炉改造煤——煤气混燃的流化床锅炉的实践

将链条锅炉改造成以煤矸石和煤气(焦炉煤气和高炉煤气)为燃料的低速、低循环倍率流化床锅炉,将焦铁企业洗选剩下的煤矸石、炼焦炉排放出来的焦炉煤气和炼铁炉排放出来的高炉煤气用于流化床锅炉发电以供给炼铁高炉风机等用电设备使用;锅炉排出的冷渣、飞灰收集起来作为生产水泥和矸石砖的原料,实现了节能减排和资源的综合利用。     

关于高炉炉缸长寿的关键问题解析

 高炉长寿化是大型高炉发展的必然趋势,实现高炉长寿的关键在于弄清高炉侵蚀的根本原因。从高炉炉缸侵蚀机理、高炉炉缸象脚型侵蚀原因、高炉炉缸圆周方向侵蚀不均匀性、高炉冷却强度与冷却效率以及高炉炉缸维护技术等5个方面探讨了高炉长寿存在的共性问题,指出高炉炉缸炭砖损毁的本质是碳不饱和铁水对炭砖的溶蚀。具体结果表明,首先,高炉炉缸象脚型侵蚀最严重部位位于高炉炉缸死料柱的根部位置;其次,阐明了直接导致高炉存在不均匀侵蚀的主要原因在于冷却系统的冷却水量和送风系统的风量在高炉周向方向分配不均匀;然后,阐明了冷却系统的作用本质是降低耐火材料热面温度,并提出了高炉冷却强度指数及高炉冷却效率指数;最后,分析了采用无钛矿护炉和钛矿护炉两种模式的高炉炉缸维护技术。