Monitoring Method for Blast Furnace Wall With Copper Staves

A monitoring method that has been designed for the first time for blast furnace wall with copper staves manufactured in China was introduced. Combining the method of ＂inverse problem＂ and the concept ＂non-inverse problem＂, the monitoring program for blast furnace wall with copper staves has been realized, which can be used to calculate online the accretion thickness and temperature of hot surface of copper staves after obtaining the values of thermocouples of copper staves. The accretion state obtained in the actual investigation has proved that the result of the program is correct. The monitoring program shows that the accretion would easily fluctuate when the accretion layer is extremely thick or thin, thereby the stable and smooth operation of the blast furnace is hindered. By maintaining appropriate accretion thickness, both long campaigns and high productivity of the blast furnace can be achieved; furthermore, it can also optimize the operation of blast furnace and maximize its production. Approximately 30--50 mm in thickness of accretion layer is maintained on the wall of Shougang blast furnace 2, which can meet the requirement for obtaining both long campaign and high productivity.

Experimental study on heat transfer characteristics of blast furnace copper staves

Much attention has been paid to copper staves because they have excellentperformance and longevity. The hot test of copper staves was carried out using all-scale staveexperiment system and according to the results, the temperature distribution and heatcharacteristics were studied. The result shows that copper stave possesses outstanding heat transferability, a well-distributed temperature field and low temperature on the hot side. In addition, amodel was established to calculate the cooling water channels' inner face temperature. Thecalculation results indicates that the highest temperature of the inner wall of the channels is 42deg C, and at the same time, the cold side of the stave temperature is 42-43 deg C. That is to say,the temperature in the stave is quite uniform.

Quantificational indexes for design and evaluation of copper staves for blast furnaces

The quantificational and normative design is the precondition of improving the design of copper staves for blast furnaces. Based on a 3-dimensional temperature field calculation model, from the view point of heat transfer and long campaigns note with the core of forming accretion, the forming-accretion-ability （FAA） and the rib hot surface maximum temperature difference （ATmax） as quantificational indexes to direct and evaluate the design of copper staves for blast furnaces were presented. The application of the two indexes in design essentially embodies the new long campaigns in the stage of design. With the application of the two indexes, good results can be obtained. Firstly, it was suggested that the rib height of a copper stave can be reduced to 15 mm, which is a new method and theory for the reduction of copper staves. Secondly, the influence of insert on FAA and ATmax, is decided by the volume of insert. According to this, the principle of design for the hot surface geometry of copper staves was put forward that the ratio of the rib hot surface to the copper stave hot surface （abbreviated as the ratio of rib to stave） must be maintained in the range of 45% to 55%; for the present copper stave with a 35-40 mm thick rib, the ratio of rib to stave in the range of 50% to 55% can optimize the design of copper staves; for the copper stave with a smaller rib thickness, for example 15 ram, the ratio of rib to stave in the range of 45% to 50% can optimize the design of copper staves. It can be summarized that the thicker the rib thickness, the larger is the ratio of rib to stave. 2008 University of Science and Technology Beijing. All rights reserved.

Analysis of temperature,stress,and displacement distributions of staves for a blast furnace

The temperature of gas flow inside a blast furnace （BF） changes significantly when the blast furnace is under unstable operations, and the temperature and stress distributions of cooling staves （CS） for BF work the same pattern. The effect of gas temperature on the temperature, stress, and displacement distributions of the cooling stave were analyzed as the gas temperature inside the blast furnace rose from 1000 to 1600℃ in 900 s. The results show that both the temperature and temperature gradient of the hot side of CS increase when the gas flow temperature inside BF rises. The temperature gradient of the hot side of CS is greater than that of the other area of CS and it can reach 65℃/mm. In the vertical direction of the hot side of CS, closer to the central part of CS, the stress intensity is greater than that of the other area of the hot side of CS, which causes cracks on the hot side of CS in the vertical di- rection. As the gas temperature increases, the stress intensity rate near the fixed pin increases and finally reaches 45 MPa/s. Fatigues near the fixed pin and bolts are caused by great stress intensity rate and the area around the pin can be damaged easily. The edge of CS bends toward the cold side and the central part of CS shifts toward the hot surface.

Stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling

The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent.

3-D temperature distribution of a full size BF copper stave with oblate channel

An experiment of a new type full size copper stave for a real blast furnacewas carried out in a special-designed experimental system. The 3-D temperature distribution insidethe stave including isotherm was obtained based on the experiment data. And the effects of thetemperature of cooling water and the velocity of the water as well as the temperature of the furnaceon the 3-D temperature distribution were obtained. The experimental and calculation results showthat the highest temperature of the hot surface is lower than 90 deg C which is very good for thesolidified slag formation on the hot surface and protecting the stave.

Model of Forming-Accretion on Blast Furnace Copper Stave and Industrial Application

Copper staves have been equipped on nearly all of BF （blast furnaces） with volume over than 1000 m3 in China since their introduction from abroad about more than 10 years ago. Because of short application and lack of experience, phenomena of thickened or naked of copper stave happen occasionally which influence production severely. So it is important to study the model of forming-accretion on BF copper stave and realize real-time monitoring of forming-accretion on different copper staves. Therefore, mathematic model of calculating accretion thickness by heat flow of BF is proposed, and the calculated results indicate that accretion thickness could be kept at a reasonable range of around 50 mm by controlling heat flux around 22.0 kW/mz. The monitoring program based on the model was applied to a certain BF in China successfully, and it is found that slip of BF near the inner wall is one of most important reasons that cause fluctuation of accretion thickness. During the period of scheduled maintenance of the certain BF, the thickness of accretion measured through the static pressure holes is in good accordance with the value calculated by the monitoring program, so the results calculated by the monitoring program can be used to guide industrial production

Numerical simulation of slag layer and its distribution on hot surface of copper stave based on ANSYS birth-death element technology

The core of the long-life copper stave was to ensure the stability of the slag layer,and the uniform distribution of the slag layer was beneficial to restrict the generation of the overthick slag layer.A novel model for calculating the thickness and distribution of the slag layer in the part of copper stave was established based on the finite element theory through the ANSYS birth-death element technology.The distribution and thickness of the slag layer on the hot surface of copper stave were calculated and analyzed when the gas temperature and slag properties tended to be changed,which was applied to characterize the slag-hanging capability of copper stave with the changes of furnace conditions.It was shown that the thickness of hot surface slag layer in the part of copper stave decreased obviously while the temperature of stave body raised rapidly with increasing gas temperature.When the gas temperature was 1400℃,the inlaid slag layer was gradually melted,and the maximum temperature of the stave body was closed to 120℃.The change of gas temperature was very sensitive to the adherent dross capability of copper stave which would be enhanced by the promotion of slag-hanging temperature.However,when the slag-hanging temperature was 1150℃and the gas temperature was lower than 1250℃,the overlhick slag layer was easily formed on the hot surface of the copper stave,and its stability was poor.The improvement in the thermal conductivity of slag could be conducive to the formation of the uniform and stable slag layer on the hot surface of copper stave,especially in the dovetail groove.When the thermal conductivity of the slag was greater than 1.8 W m^(-2)℃^(-1),the inlaid slag layer in the dovetail groove was not melted,although the gas temperature reached 1500℃.

Thermal test and numerical simulation of cooling stave with internal ribbed tube

A new type of cooling stave with internal ribbed tube was proposed,and the heat transfer performance of the stave was studied by means of thermal test and numerical simulation.The temperature of cooling stave was monitored in the conditions of furnace gas temperature of 200-700 C and cooling water velocity of 0.2-1.0 m/s.The thermal test results show that the internal rib structure can form swirl in the water pipe and improve the cooling capacity of the cooling stave.The higher the furnace temperature or the lower the cooling water flow rate,the more obvious the advantage of the cooling stave with internal ribbed tube.The mathematical model of the cooling stave with internal ribbed tube was established by FLUENT software,and the influence of the internal rib structure parameters on the heat transfer performance of the cooling stave was discussed.It is suggested that the parameters of the internal ribbed tube should be 4 ribs,1 mm in height,5-7 mm in width,and 20-30 mm in lead.In the same common working conditions of the cooling stave,the maximum temperature of the newly designed cooling stave with internal ribbed tube is reduced by 5.6%compared with that of common cooling stave with round tube.The water flow rate in the internal ribbed tube only needs 0.9 m/s to reach the cooling effect of 2 m/s in the common tube cooling stave,which can save 55%of water.In case of water shortage accident of cooling stave,the maximum temperature of the cooling stave with internal ribbed tube is decreased by 22.4%compared with that of common round tube,which can effectively reduce the harm of water shortage and protect the cooling stave.

Eating Breakfast May Stave Off Obesity,Diabetes

选注者言:在过去的8年中,Pereira博士对近3000名年龄在25至37岁之间的成年人的饮食习惯及健康状况进行了跟踪调查。结果发现,与那些偶尔吃早餐或根本不吃早餐的人相比,每天坚持吃早餐的人患肥胖症和糖尿病的几率降低了35％至50％。研究人员说,不吃早餐容易导致人体内胰岛素的缺失。而它的缺失往往是糖尿病的先兆。另一方面,吃早餐有助于控制饮食,避免人在一天中的其余时间因为吃地过多而逐渐变得肥胖。

Rosuvastatin helps stave off contrast nephropathy in NSTE-ACS patients

Key points： PRATO-ACS randomized NSTE-ACS patients to rosuvastatin or control prior to PCI Statin resulted in significant decrease in nephropathy, better short-term outcomes Data needed to elucidate class effects of statins, causality

Brushing, Flossing Stave Off Diabetes

人类对人体奥秘的探索与了解尚处初级阶段。本文提出的一个问题就让我们感到新奇与愕然。洁齿与口腔卫生有助于抑制糖尿病: Gum(齿龈)disease may even be more important than obesity or age as a factorin the onset of diabetes in adults。 上句可译:就诱发成年人糖尿病的因素而言,齿龈疾病也许比肥胖和年龄这两个因素更为重要。 因此,我们有必要认识:the importance of prevention and early treatment ofgum disease in people who are at risk of developing diabetes。 本文对inflammation([医]炎症,发炎)提出了一个颇有原创性的观点:…heart disease has a substantial inflammatory component。】

强化换热管冷却壁传热分析及结构优化

强化冷却水管的换热,对提高冷却壁的传热性能、延长冷却壁使用寿命有重要意义。利用Fluent数值模拟研究了丁胞管、螺纹管、扭曲椭圆管3种强化换热管对冷却壁换热性能的影响,并对强化换热管结构参数进行了优化,建议丁胞管结构参数设定如下:丁胞纵向间距为40 mm,径向丁胞数为4,丁胞半径为2 mm;螺纹管结构参数设定肋条数为4,肋高为1 mm,肋宽为5~7 mm,导程为25~40 mm;扭曲椭圆管结构参数设定导程不大于100 mm,短长轴之比取0.4~0.6。对比分析实验结果表明:螺纹管和扭曲椭圆管对冷却壁强化换热效果较好,丁胞管较差,扭曲椭圆管可以在水管压力损失较小下实现较好的强化换热效果。

铜冷却壁长寿的使用维护及结构优化浅析

首钢股份高炉铜冷却壁的长寿使用维护经验,主要是对冷却水温、水量、水压,入炉有害元素及边沿煤气流等进行有效控制,同时对中长期休风和降料面停炉等特殊时段进行专门维护,保障铜冷却壁长期稳定安全运行。针对铜冷却壁在长期使用后可能存在的热面磨损和累积变形,采用热面镶嵌钢砖、本体加强等结构优化设计,能大幅度提高耐磨和挂渣性能,增强抗变形能力,延长在异常工况条件下的使用寿命。认为,只要铜冷却壁设计合理、使用维护得当,就完全能在保障高炉高水平稳定顺行的基础上,实现超过一代炉役的长寿目标。

基于热阻及成本分析的高炉冷却壁多目标优化

本文建立了高炉冷却壁热阻模型,冷却壁热阻包括火积耗散热阻和对流热阻,分别表征其导热性能和换热表面的对流换热性能。分析冷却壁运行过程中的各项成本,包括冷却壁材料成本、运行耗水成本、运行能耗成本以及冷却壁厚度减薄时产生的额外收益。应用遗传算法以冷却壁热阻和成本为目标函数,以冷却壁各结构参数为决策变量,对冷却壁进行多目标优化,获得了Pareto最优解集。优化后的冷却壁与初始冷却壁相比,可在传热性能相当的前提下成本下降79.9%,或在冷却成本相当的前提下,热阻下降27.3%。

沙钢2680m^(3)高炉长寿技术特点及铜冷却壁使用效果

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操作制度对高炉热负荷分布影响研究

鞍钢股份有限公司炼铁总厂利用覆盖炉体的高精度水温电偶,实现了对5#高炉各部位冷却壁热负荷的长期跟踪研究。通过研究装料制度和送风制度对高炉热负荷分布的影响,明确了边缘焦炭负荷、矿石平台宽度、鼓风动能、风口回旋区长度和炉腹煤气量对热负荷分布的具体作用效果,为高炉热负荷分布的合理性研究和调控手段研究提供了依据。

酒钢1号高炉冷却壁长寿技术应用简析

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颗粒团聚行为对弥散型核燃料芯体失效的影响分析

针对燃料颗粒团聚行为对弥散型核燃料芯体失效的影响,开发了弥散型核燃料元件代表性体元模型的参数化建模及数值计算脚本,综合考虑燃料-基体界面损伤层、燃料颗粒辐照肿胀以及环境压力等关键特征进行了数值建模,系统分析了燃料颗粒团聚体积分数、颗粒团聚位置、运行环境静水压力以及基体材料性质对弥散型核燃料芯体失效的影响规律,发现燃料颗粒团聚区域是弥散型核燃料芯体失效的起点,而运行环境静水压力对芯体应力集中有抑制作用,揭示了燃料颗粒团聚现象对弥散型核燃料元件力学性能的“短板效应”。团聚区域的燃料颗粒通过密集堆叠的方法进行几何建模,局部燃料颗粒团聚体积分数由最小颗粒间距定义。有限元计算结果表明,燃料颗粒团聚体积分数越大,弥散型核燃料芯体越容易失效。而包壳外的环境压力会降低芯体内燃料颗粒团聚区域的应力水平,但随着局部团聚程度的增加,环境压力对芯体中Mises应力的影响逐渐减小。此外,燃料颗粒团聚区域相对弥散型核燃料芯体厚度方向位置改变对芯体的最大Mises应力几乎没有影响;燃料颗粒团聚区域在弥散型核燃料芯体的面内分布位置和环境压力共同决定弥散型核燃料芯体的失效行为。本研究可为弥散型核燃料元件的失效条件预测、可靠性评估和结构优化设计提供分析方法和数值依据。

球墨铸铁冷却壁心部性能研究

球量铸铁件的心部性能成为衡量球墨铸铁冷却壁内部质量的一个重要指标。技术要求为心部抗拉强度R_(m)≥350 N/mm^(2),伸长率A≥8%;心部金相组织球化率≥70%,铁素体含量≥80%。由于球墨铸铁冷却壁属于厚大铸件,受凝固特性、冷却速度和合金元素等因素的影响,心部性能不稳定,通常无法达到技术协议的要求。本文分析了心部性能较低的原因,提出了工艺改进措施,进行了冷却壁解剖试验,验证了试验效果。