Mathematical model on heat transfer of water-cooling steel-stick bottom electrode of DC electric arc furnace

For predicting and controlling the melted depth of bottomelectrode during the process of steelmaking, the water-cooling steel-stick electrode is taken as an example, to analyze the process ofheat transfer, then 3D mathematical model by control capacity methodis built. At the same time, the measurement on the melted depth ofbottom electrode is conducted which verified the correctness of thebuilt mathematical model. On the base of verification, all kinds ofkey parameters are calculated through the application and a series ofresults are simulated. Finally, the optimum parameters are found andthe service life of bottom electrode is prolonged.

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.

Analysis and optimization of heat loss for water-cooled furnace roller

A heat transfer model of furnace roller cooling process was established based on analysis of furnace roller＇s structure. The complicated model was solved with iteration planning algorithm based on Newton search. The model is proved logical and credible by comparing calculated results and measured data. Then, the relationship between water flow velocity, inlet water temperature, furnace temperature and roller cross section temperature, outlet water temperature, water temperature rise, cooling water heat absorption was studied. The conclusions and recommendations are mainly as follows： l） Cooling water temperature rise decreases with the increase of water flow velocity, but it has small relationship with inlet water temperature; 2） In order to get little water scale, inlet water temperature should be controlled below 30 ℃. 3） The cooling water flow velocity should be greater than critical velocity. The critical velocity is 0.07 m/s and water flow velocity should be controlled within 0.4-0.8 m/s. Within this velocity range, water cooling efficiency is high and water temperature rise is little. If cooling water velocity increases again, heat loss will increase, leading to energy wasting.

Investigation on the relationship between hearth wall erosion and deadman permeability for large blast furnaces

In this study, the relationship between hearth wall erosion and deadman permeability was investigated based on the change in the hearth bottom and hearth sidewall temperatures. Additionally, the operation practice for controlling hearth wall erosion in the large No. 1 blast furnace at Baosteel was also investigated. The reasons for the decrease in the permeability of deadman coke were analyzed, and measures for improving the permeability of deadman coke and controlling hearth wall temperature rising were described. The results show that a decrease in deadman coke permeability is the main reason for refractory temperature increase and hearth wall erosion. This indicates the importance of monitoring changes in hearth working conditions and taking appropriate measures to maintain sufficient permeability of the deadman and balance the hot metal flow and drainage of slag. At this rate, the decline in the hearth bottom temperature and fast rising of the hearth wall temperature can be restrained.

Application and practice of ceramic fiber block technology in industrial furnaces

Ceramic fiber,a kind of furnace lining material, is widely utilized in industrial furnaces. Fiber blocks can be made into various shapes. They have advantages of low thermal conductivity, low density and light weight for the development of industrial furnaces, This paper, taking a continuous annealing furnace as an example, describes the application of ceramic fiber blocks in the furnace and the installation methods. The temperatures of the furnace wall with different linings are analyzed. In the furnace design or the renovation of the existing furnaces, lining with ceramic fiber blocks is the preferred solution.

Ultra Sensitive Determination and Preconcentration of Cd²⁺, Cu²⁺and Pb²⁺after Multi-Walled Carbon Nanotubes Adsorption

Multi-Walled carbon nanotubes are used as preconcentrating probes for the quantitative determination of trace cadmium, copper and lead in environmental and biological sample using graphite Furnace Atomic Absorption Spectrometry and inductively coupled Plasma Optical Emission spectrometry. The method is based on the electrostatic interactions of positively charged Cd+, Cu+ and Pb+ with the negatively charged multi-walled carbon nanotubes (MWCNTs) for the preconcentration and isolation of analytes from sample solutions. Effective preconcentration of trace cadmium, copper and lead was achieved in a pH range of 5 - 7, 5 - 7 and 4 - 7, respectively. The retained cadmium, copper and lead were efficiently eluted with 0.3 mol·L-1 HCl for graphite Furnace Atomic Absorption Spectrometry determination. The multi-walled carbon nanotubes packed micro-column exhibited fairly fast kinetics for the adsorption of cadmium, copper and lead, permitting the use of high sample flow rates up to at least 3 mL·min-1 for the flow injection on micro-column preconcentration without the loss of the retention efficiency. The detection limits (3σ) were 0.03, 0.01 and 0.5 ng·mL-1 for Cd, Cu and Pb, respectively. The relative standard deviation under optimum condition is less than 2.9% (n = 10). The developed method was successfully applied to the determination of trace Cd, Cu and Pb in a variety of environmental and biological samples.

一种高硬度复杂薄壁翼片的机械加工工艺设计

一种高硬度复杂薄壁翼片目前没有高速铣削的加工手段可利用,需要普通铣削结合真空炉处理的方式来满足产品技术要求,加工难度大,生产进度紧。通过工艺攻关、工艺优化形成了翼片的机械加工工艺方案,采用普通铣削后进行真空炉淬火的方式保证翼片角度、厚度、孔径和力学性能要求,最后用电火花切割的方式将工件与工艺台分离保证翼轴孔距和外形尺寸。结合真空炉处理和电火花切割的特点,及时处理了加工过程中出现的热处理变形、切割外形导致孔距超差等技术问题,最终保证首批次合格产品按进度交付。所涉及到的翼片工艺方案、工艺台、定位基准选择、控制热处理变形的工装、电火花切割工装等内容属于西安现代控制技术研究所首次应用,具有创新性,对于弹体结构件中技术要求较高的翼片及同类结构的零件有一定的参考价值。

新钢10号高炉降料面处理炉墙结厚实践

新钢10号高炉因烧结矿质量波动较大、炉况稳定性差及管道频繁发生等原因,出现炉墙结厚。首次采用降料面的方法处理炉墙结厚,降料面过程中炉况稳定,恢复上料后24h内炉况恢复正常。认为在降料面的过程中应密切关注煤气中H_(2)、O_(2)含量的变化,确保含H,量≤12%;随着料面的下降,炉墙结厚物逐步显露之后,结厚物下部受到高温煤气流冲刷作用,上部受到炉顶雾化水冷却作用,结厚物产生裂缝塌的过程中,温度的变化是关键。10号高炉炉墙结厚处理后,主要技术经济指标明显改善,日产量上升155Vd,煤气利用率上升1.1个百分点,燃料比下降10kg/t。

梅钢5号高炉炉墙结厚的原因及炉况恢复

对梅钢5号高炉炉墙结厚的原因及炉况恢复进行了总结。5号高炉开炉以来首次炉墙结厚,主要征兆是全炉水温差下降和炉身静压力曲线值出现偏差。结厚的主要原因:一是焦炭质量劣化,入炉焦炭CRI最高上升至23.6%左右,灰分在12.5%左右;二是烧结矿质量劣化,品位降至57.0%左右,FeO含量降至8.5%左右;三是炉渣(Al_(2)0_(3))最高上升至19.0%左右;四是入炉有害元素含量超标,锌负荷升至0.36 kg/t,碱金属负荷最高上升至3.0 kg/t;五是炉况持续恶化。通过采取发展边沿气流、提高入炉风量、提高炉温加锰矿洗炉等措施,炉况得到恢复。

酒钢4#高炉冷却壁破损原因分析及对策

酒钢4#高炉中修开炉运行仅1 a后出现炉腹、炉腰、炉身下部冷却壁大量破损,已影响到高炉的操作及生产稳定。结合4#高炉中修后的生产实际状况,并与3#高炉对比,分析冷却壁破损的原因,并提出相应对策,为缓解炉身冷却壁损坏改善高炉运行提供依据。

包钢5^(#)高炉炉缸侧壁温度升高的分析与防治

高炉炉缸是制约高炉寿命达到15年以上的关键部位,也是决定高炉寿命的关键因素。针对5^(#)高炉炉缸侧壁温度升高,通过对炉缸侵蚀机理的研究,判定铁水环流加剧、炭砖侵蚀严重是炉缸侧壁温度升高的直接原因。5^(#)高炉通过采取制定预警标准、强化日常管理、优化铁口深度标准与加强维护、根据三级预警调整生产操作参数等防治措施,炉缸侧壁标高8.663 m处铁口区温度均下行,停炉前基本稳定在350~450℃,处于可控范围。

Numerical Analysis of Flow Instability in the Water Wall of a Supercritical CFB Boiler with Annular Furnace

In order to expand the study on flow instability of supercritical circulating fluidized bed(CFB) boiler,a new numerical computational model considering the heat storage of the tube wall metal was presented in this paper.The lumped parameter method was proposed for wall temperature calculation and the single channel model was adopted for the analysis of flow instability.Based on the time-domain method,a new numerical computational program suitable for the analysis of flow instability in the water wall of supercritical CFB boiler with annular furnace was established.To verify the code,calculation results were respectively compared with data of commercial software.According to the comparisons,the new code was proved to be reasonable and accurate for practical engineering application in analysis of flow instability.Based on the new program,the flow instability of supercritical CFB boiler with annular furnace was simulated by time-domain method.When 1.2 times heat load disturbance was applied on the loop,results showed that the inlet flow rate,outlet flow rate and wall temperature fluctuated with time eventually remained at constant values,suggesting that the hydrodynamic flow was stable.The results also showed that in the case of considering the heat storage,the flow in the water wall is easier to return to stable state than without considering heat storage.

预制模块化高炉渣纤维保温外墙板传热分析

该研究旨在分析预制模块化高炉渣纤维保温外墙板的传热性能,评估其在建筑保温领域中的应用潜力。通过实验测试获取高炉渣纤维保温外墙板的物理性质和热导率,并进行传热分析。研究发现,预制模块化高炉渣纤维保温外墙板具有较低的热导率和良好的隔热性能。通过传热分析,观察到该外墙板可以有效地减少室内外温度差异,降低热能传递损失。此外,建筑内部的温度稳定性得到改善,达到良好的节能效果。基于传热分析的结果,预制模块化高炉渣纤维保温外墙板在建筑保温领域具备广阔的应用前景,有助于降低能源消耗,并提供舒适的室内环境。该研究为高炉渣纤维保温材料在建筑行业中的应用提供理论支持,为能源节约和减排作出贡献。

临淄区农村燃气壁挂炉采暖住宅耗气量分析及改造

研究淄博市临淄区农村壁挂炉采暖室温与能耗的关系。在采暖季,通过典型用户实测,探讨室内温度、通风时间及围护结构参数对农村壁挂炉采暖住宅耗气量的影响,利用DeST软件分析天然气采暖的能耗状况,针对当地农宅实际情况设计围护结构的改造方案并进行模拟分析。研究表明,节能改造后的农宅在采暖季的能耗下降53%~61%。

昆钢2号高炉炉况失常的原因及处理措施

对昆钢2号高炉2023年4月8日发生的炉况失常的原因及处理措施进行分析总结。认为这次炉况失常的直接原因是风口小套长时间漏水和炉墙黏结,间接原因是高炉计划检修周期过长、烧结矿冶金性能劣化、熔剂质量波动造成渣相波动和炉顶洒水效果不好。从装料制度、送风制度、造渣制度、热制度等方面进行系统调整,主要通过采取缩矿批退负荷、集中加焦、调整布料矩阵、增加水量提高冷却强度等措施,炉况实现快速恢复。4月12日,2号高炉焦炭负荷提升至4.54,日产量恢复到7058.789t/d,燃料比稳定在516kg/t。

首钢股份2号高炉炉墙结厚的成因及处理

首钢股份2号高炉因原燃料质量变差、抗原料质量波动能力差、操作应对不及时等原因导致炉墙结厚,炉况波动时间较长。通过采取减轻焦炭负荷、调整装料制度、降低炉渣碱度、使用萤石洗炉、更换风口等措施进行处理,炉况恢复正常。认为:①当进厂焦炭质量不达标时,应及时向上反馈,以免造成生产困难;②在原燃料质量稳定性较差的条件下,应保持煤气流通路,重视中心气流的作用,提高抗外围原燃料质量波动的能力;③针对原燃料条件及其质量波动,应及时修改、制订调整措施,保证高炉顺行。

湘钢2号高炉炉身上部结瘤的原因及处理

对湘钢2号高炉炉身上部结瘤的原因及处理进行了阐述。2号高炉从炉墙轻微结厚,逐步发展成为较为严重的结瘤,瘤体厚度达800mm以上,分析结瘤的原因,主要是块矿入炉粉末多及烧结矿质量劣化,炉内碱金属循环富集现象严重,炉身中上部冷却强度过大。根据2号高炉自身实际状况,采用物理击打法消除结瘤,实现了炉况的快速恢复,生产指标明显改善。这次结瘤处理过程教训深刻,认为高炉操作炉型的维护应以预防为主,无论是结厚还是结瘤,预防是关键,处理要及早,不能犹豫不决。

高炉炉墙结厚机理探究

高炉生产过程中存在多种因素造成高炉炉墙结厚,当结厚发生时高炉各操作参数及炉况顺行也会发生变化。对高炉炉墙结厚机理进行探究,通过确定结厚的位置,计算黏结物厚度,采取热洗、炸瘤等方式来消除高炉结厚,从而实现高炉炉况稳定顺行,不断改善高炉技术经济指标。

铝熔炼炉内衬局部修复工艺研究及应用

铝熔炼炉内衬小面积破损,若继续使用破损将进一步扩大,安全风险增高,最终被迫停炉中大修,针对该问题,采取了内衬局部修复工艺,有利于炉内衬整体使用寿命延长,可使工期缩短33%以上,内衬检修项目同比减少30.1%。

炉内壁结焦对工业炉性能的影响研究

针对工业炉在工作过程中的结焦失效问题,研究炉内壁结焦对工业炉性能的影响。选取型号为DG1025/18.3-II5的工业炉作为研究对象,分析工业炉内壁的结焦机理,然后利用有限元软件ABAQUS构建有限元分析模型,设定模型内结焦层网格相对细密、工业炉金属网格相对稀疏,最后设定模型边界条件与工况负荷,开展炉内壁结焦对工业炉性能的测试。研究结果显示,煤粉粒径会对工业炉内壁结焦厚度造成影响,粒径越大,其结焦厚度越大;随着结焦厚度的提升,工业炉的屈服强度、抗拉强度及伸长率都呈下降趋势,说明炉内壁结焦会对工业炉的强度与塑性产生消极影响,即其结焦厚度与工业炉的力学性能呈反比例相关;随着结焦厚度的提升,工业炉金属基体同结焦层界面处的温度逐渐提升,工业炉内外壁温差逐渐提升,即工业炉内壁结焦会对其传热性能造成破坏;工业炉内壁产生结焦时,工业炉外壁径向变形量低于内壁,随着结焦厚度提升,内外壁的径向变形量均表现出提升趋势,当变形量达到一定值后,将造成工业炉局部胀裂,进而破坏其机械性能。综上,工业炉内壁结焦会对其力学性能、传热性能及机械性能造成破坏。