New Type Regulating Valve Applied in Cooling System of Blast Furnace

A new type regulating valve with the cooling mode of constant temperature difference water supply, temperature difference self operated regulating valve, was introduced into blast furnace cooling system to overcome shortcomings of the cooling mode of constant flow rate water supply. The results show that the temperature difference between inlet and outlet water of cooling wall can be decreased greatly and steadily, and the water supply for blast furnace cooling can be reduced considerably.

Cooling Water Flow Rate Calculation for Hearth of Large Blast Furnaces

The cooling water flow rate for hearth of large blast furnaces was calculated by simulation. The results show that the cooling water flow rate shall be above 4 200m3/ h for hearth of large blast furnaces; to meet requirements of the increasing smelting intensity and to ensure the safety at the end of the first campaign,the designed maximum cooling water flow rate should be 5 900m3/ h; according to the flow distribution stability and the calculated resistance loss,hearth cooling stave pipes with the specification of 76 mm × 6 mm shall be adopted to assure the flow velocity in pipes of hearth cooling stave in the range of 1. 9- 2. 3 m / s.

Designing for Long Campaign Life Blast Furnace (1)──The Mathematical Model of Temperature Field for Blast Furnace Lining and Cooling Apparatus and New Concept of Long Campaignship Blast Furnace Cooler Design

The physical and mathematical model of temperature field for blast furnace stave coolers was established. The computation results show that the heat resistance of 2-6 mm water scale within the cooling pipe is about 7%-20% of the total heat resistance of cooling stave body, as for drilling duct type, the heat resistance of 2-6 mm water scale is about 88%-98% of the total heat resistance. Using drilling duct or full cast pipe can eliminate gas clearance and coating layer between pipes and cast iron body and reduce the heat resistance of the cooler sharply and improve the coefficient of heat transfer to a great extent. The water velocity within coolers can be kept at the 1evel of 0.5- 1 .5 m/s, the higher water velocity can not decrease the hot surface temperature, but can increase energy consumption for cooling water.

Effect of cooling rate on the crystallization behavior of perovskite in high titanium-bearing blast furnace slag

The effect of cooling rate on the crystallization of perovskite in high Ti-bearing blast furnace（BF） slag was studied using confocal scanning laser microscopy（CSLM）. Results showed that perovskite was the primary phase formed during the cooling of slag. On the slag surface, the growth of perovskite proceeded via the successive production of quasi-particles along straight lines, which further extended in certain directions. The morphology and structure of perovskite was found to vary as a function of cooling rate. At cooling rates of 10 and 30 K/min, the dendritic arms of perovskite crossed obliquely, while they were orthogonal at a cooling rate of 20 K/min and hexagonal at cooling rates of 40 and 50 K/min. These three crystal morphologies thus obtained at different cooling rates respectively corresponded to the orthorhombic, cubic and hexagonal crystal structures of perovskite. The observed change in the structure of perovskite could probably be attributed to the deficiency of O^2-, when Ti2O3 was involved in the formation of perovskite.

Application of Air-cooled Blast Furnace Slag Aggregates as Replacement of Natural Aggregates in Cement-based Materials：A Study on Water Absorption Property

The influence of air-cooled blast furnace slag aggregates as replacement of natural aggregates on the water absorption of concrete and mortar was studied, and the mechanism was analyzed. The interface between aggregate and matrix in concrete was analyzed by using a micro-hardness tester, a laser confocal microscope and a scanning electron microscope with backscattered electron image mode. The pore structure of mortar matrixes under different curing conditions was investigated by mercury intrusion porosimetry. The results showed that when natural aggregates were replaced with air-cooled blast furnace slag aggregates in mortar or concrete, the content of the capillary pore in the mortar matrix was reduced and the interfacial structure between aggregate and matrix was improved, resulting in the lower water absorption of mortar or concrete. Compared to the concrete made with crushed limestone and natural river sand, the initial absorption coefficient, the secondary absorption coefficient and the water absorption capacity through the surface for 7 d of the concrete made from crushed air-cooled blast furnace slag and air-cooled blast furnace slag sand were reduced by 48.9%, 52.8%, and 46.5%, respectively.

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.

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.

Physical Properties of Crushed Air-cooled Blast Furnace Slag and Numerical Representation of Its Morphology Characteristics

Physical properties and geometrical morphologies of crushed air-cooled blast furnace slag （SCR） and crushed limestone （LCR） were comparatively investigated. The shape, angularity, surface texture and internal pore structure of aggregate particles for different size and gradation were numerically represented by sphericity （ψ） and shape index （SI）, angularity number （AN）, index of aggregate particle shape and texture （IAPST）, porosity and pore size, respectively. The results show that SCR is a porous and rough aggregate. Apparent density, void, water absorption and smashing index of SCR are obviously higher than those of LCR with the same gradation, respectively. However, bulk density of SCR is lower than that of LCR with the same gradation. SI, AN, IAPST and porosity of SCR are obviously higher than those of LCR with the same gradation, respectively. The smaller particle size of SCR, the larger of its AN, IAPST and porosity.

Effect of Crushed Air-cooled Blast Furnace Slag on Mechanical Properties of Concrete

Morphology characteristics of mix aggregates with crushed air-cooled blast furnace slag（SCR） and crushed limestone（LCR） with 5-20 mm and 20-40 mm gradation were represented by numerical parameters including angularity number（AN） and index of aggregate particle shape and texture（IAPST）.The effect of mix aggregates containing SCR on compressive strength and splitting tensile strength of concrete was investigated.Fracture characteristics of concrete,interfacial structure between aggregates and matrix were analyzed.The experimental results show that porous and rough SCR increases contact area with matrix in concrete,concave holes and micro-pores on the surface of SCR are filled by mortar and hydrated cement paste,which may increase interlocking and mechanical bond between aggregate and matrix in concrete.SCR can be used to produce a high-strength concrete with better mechanical properties than corresponding concrete made with LCR.The increase of AN and IAPST of aggregate may enhance mechanical properties of concrete.

Possibility of Sea Water as Mixing Water in Concrete

In the near future, fresh water will be very difficult to get and scarce. It is said that in 2025 half of the mankind will live in the areas where fresh water is not enough. Also, UN and WMO （World Meteorological Organization） are predicting five billion people will be in short of even drinking water. Also, in the present, there are some areas where sea water or chloride contained sand are used as mixing water with or without intension. The authors believe that the possibilities of using sea water as mixing water in concrete should be investigated seriously. In this paper, the authors would like to show various possibilities of using sea water as mixing water in RC （reinforced concrete） members. The possibilities are shown as follows： （1） mixed with pozzolanic materials （Blast furnace slag powder, etc.） expecting to fix the free chloride ion; （2） Mixed with corrosion inhibitor; （3） reinforced with stainless steel or corrosion resistant reinforcement; and （4） used in very dry or submerged conditions.

Tests on Alkali-Activated Slag Foamed Concrete with Various Water-Binder Ratios and Substitution Levels of Fly Ash

To provide basic data for the reasonable mixing design of the alkali-activated (AA) foamed concrete as a thermal insulation material for a floor heating system, 9 concrete mixes with a targeted dry density less than 400 kg/m3 were tested. Ground granulated blast-furnace slag (GGBS) as a source material was activated by the following two types of alkali activators: 10% Ca(OH)2 and 4% Mg(NO3)2, and 2.5% Ca(OH)2 and 6.5% Na2SiO3. The main test parameters were water-to-binder (W/B) ratio and the substitution level (RFA) of fly ash (FA) for GGBS. Test results revealed that the dry density of AA GGBS foamed concrete was independent of the W/B ratio an RFA, whereas the compressive strength increased with the decrease in W/B ratio and with the increase in RFA up to 15%, beyond which it decreased. With the increase in the W/B ratio, the amount of macro capillaries and artificial air pores increased, which resulted in the decrease of compressive strength. The magnitude of the environmental loads of the AA GGBS foamed concrete is independent of the W/B ratio and RFA. The largest reduction percentage was found in the photochemical oxidation potential, being more than 99%. The reduction percentage was 87% - 93% for the global warming potential, 81% - 84% for abiotic depletion, 79% - 84% for acidification potential, 77% - 85% for eutrophication potential, and 73% - 83% for human toxicity potential. Ultimately, this study proved that the developed AA GGBS foamed concrete has a considerable promise as a sustainable construction material for nonstructural element.

The Impact of Marine Water on Different Types of Coarse Aggregate of Geopolymer Concrete

This research studies the impact of different types of coarse aggregate on the behavior of geopolymer concrete based on both fly ash (FA) and ground granulated blast furnace slag (GGBFS) in different marine environments. Aiming to solve the problems caused by the construction and demolition waste and the depletion of natural aggregates, in the present study coarse recycled aggregates is used to produce new green concrete with a fly ash-slag based geopolymer. By this examination, the research seeks to improve the quality and productivity of concrete used in construction and hydraulic projects. For this research, four mixtures containing different types of coarse aggregate in two different water environments were used. The utilized mixtures contained natural aggregate concrete (NAC) such as basalt and crushed marble. Also, recycled coarse aggregate concrete (RAC), which totally replaced natural aggregate, was presented in this paper such as crushed concrete and crushed ceramic. For this study, in the sieve analysis;specific and unit weights, was recorded. Furthermore, the mechanical properties were determined, using a compressive test that was conducted on the 7th, 28th, 56th and 90th days at different water environments;potable water (PW) and sea water (SW). Durability test was also performed for total absorption measurement. Results indicated that geopolymer concrete exhibits better strength in marine environments than in those of potable water. Results also showed that crushed marble (CMA) exhibits higher compressive strength and durability.

石墨炉原子吸收测定间接空冷机组循环水中的痕量铝

采用石墨炉原子吸收测定SCAL型间接空冷机组循环水中的痕量铝,从石墨炉工作参数、基体改进剂、试剂空白、水样前处理等方面进行了实验条件优选。实验结果表明:石墨炉灰化温度、原子化温度分别为700℃和2 700℃,不加基体改进剂条件下,铝离子标液质量浓度在0~20μg/L范围内标准曲线线性相关系数可达到0.999 8,相对标准偏差小于10%,检测下限为0.5μg/L。采用水样酸化静置1 h后直接测定并与标准加热消解法测定值进行了对比,相对误差小于5.0%,空白值小于0.5μg/L,有效解决了加热消解法空白值高的问题,提高了间接空冷机组循环水中小于10μg/L痕量铝测定的准确性。

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%。

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。

石油焦煅烧工艺冷却方式的对比与分析

对比分析回转窑和罐式炉不同的冷却方式,采用冷却效率高,并且对高温煅后焦热量可以余热利用的冷却技术正在成为新的发展方向。回转窑间接冷却不仅可以产生90℃的热水,而且还能解决直接喷淋冷却带来的焦粒粉化问题,是新建或者改造项目的优选工艺。罐式炉汽化冷却方式可以产生250~300kg/t-CPC的饱和蒸汽,经济性明显,是降低双碳排放的重要技术,但是产业化应用还需要解决水套材料、寿命方面的问题。

新钢7^(#)高炉炉凉事故分析与处理

新钢7^(#)高炉在有上部结厚的情况下计划检修,休风期间炉墙西南结厚物整体坍塌,复风过程因结厚物进入炉缸破坏了热平衡,补加净焦量不够,风口自动吹开,使用质量差的烧结开机料,最终造成炉温大凉。本文通过对高炉炉凉事故起因、处理经过及恢复到正常三个阶段进行了分析,为处理高炉炉凉事故快速恢复提供了宝贵经验。

还原磁化焙烧竖炉冷却系统研究

某氧化铁矿石属于难选铁矿石,磁化焙烧工艺是处理此类铁矿石最有效的方法之一。竖炉磁化焙烧工艺加工成本相对较高,其中竖炉冷却系统是竖炉加工成本的重要组成部分,通过对竖炉冷却系统冷却水速、水箱梁水垢、水箱梁冷却水量等方面的研究,探索高效、节能的竖炉冷却系统.

沙钢2680m^(3)高炉长寿技术特点及铜冷却壁使用效果

沙钢2680m高炉设计及操作遵从炉料膨胀、收缩与炉型相适应的原则,通过设计合理炉型、优化铜冷却壁设计及操作制度等,延长铜冷却壁寿命。炉型设计采用合理的炉腰体积占比(12%~16%);优化炉身上部结构,减少铸铁冷却壁厚度,增加耐材厚度,可降低炉身上部冷却强度,避免边沿气流温度过低影响炉料的干燥和预热;优化铜冷却壁设计,壁体采用侧凸台,加强高炉周向传热的均匀性;优化操作制度,合理调剂上下部制度,增大炉缸活跃区占比,避免软熔带根部位置过低。采用上述措施后,2680m高炉铜冷却壁寿命普遍超过17年,部分达到23年。

酒钢1号高炉冷却壁长寿技术应用简析

酒钢1号高炉大修停炉检查冷却壁基本完好,5~7段铜冷却壁的使用效果明显优于8、9段铸铁冷却壁。1号高炉冷却壁使用效果较好,主要是采用了优化设计炉型、铜冷却壁、增加冷却水量提高冷却强度、联合软水密闭循环冷却系统等技术;同时,存在炉身中下部铸铁冷却壁冷却水流速偏小、冷却强度不足的问题,不易形成稳定的渣皮。认为,铜冷却壁上部的铸铁冷却壁是制约高炉长寿的重要环节,应结合高炉实际原燃料条件和操作制度优化设计,增加炉身下部铜冷却壁的高度,将铜冷却壁延伸至干湿交接部位。