铸件退火炉烟气余热的回收利用装置

提出了HTAC技术的新结构,即铸件退火炉烟气余热的回收利用装置,以期提高热效率、节约能源并减轻污染。     

热镀锌机组退火炉节能优化的数值模拟

针对某钢铁公司热镀锌机组退火炉直燃加热段(DFS)内复杂的燃烧、流动、传热过程与其操作参数的关系,利用CFD技术进行建模与仿真计算,研究了烧嘴的空燃比与空气预热温度对炉内组分浓度场与温度场的影响。模拟结果表明,直燃加热段空燃比在4. 0及以下,炉段内的还原性气氛符合生产工艺的要求;模拟找出了与试验工况截面温度一致的几组优化组合操作参数(空燃比/空气预热温度),分别为3. 7/720 K、3. 8/600 K、3. 9/450 K和4. 0/300 K,此时DFS出口及中心截面的平均温度与试验工况的3. 5/600 K一致,其中4. 0/300 K工况下,煤气用量减少11. 88%,节约能源明显。     

2080mm连续退火炉工艺流程及先进控制技术

文章以邯钢2080mm连续退火炉为研究对象,简要介绍了连续退火炉的工艺流程布置和先进装备,阐述了利用烟气余热对助燃空气和预热段的带钢进行预热以及生产过热水的余热回收技术,通过控制炉辊凸度来预防带钢跑偏、热瓢曲和褶皱炉辊凸度控制技术,通过向快冷段注入氢气提高冷却速率的高氢注入技术,以及利用数学模型进行钢卷过渡管理等各种先进控制技术。生产实践表明,先进的装备及控制技术保证了连续退火炉的稳定运行,并在节能、温度控制、提高和改善产品质量及生产过程控制等方面取得了良好效果,为企业带来了可观的经济效益与社会效益。     

适用于重熔铝锭及废料的高效节能熔铝炉

为提高火焰熔铝炉的热效率,分析了目前常用熔铝炉型的工作原理及结构,找出各自的优缺点,指出火焰熔铝炉充分利用高温炉气是提高热效率的主要方法。针对现有火焰炉加热时局部温度过高、传热受限的弊端,设计了可上下调节、左右摆动的高速烧嘴。运用对流传热的牛顿定律,设计了适用于重熔铝锭及废料的加热与预热同时进行的双层膛火焰炉,增加了高温气流与炉料的接触面积,强化了对流传热的作用。新型熔铝炉充分利用了余热预热炉料和助燃空气,使熔铝炉的热效率提高到55%以上。     

连续式加热炉节能措施

本文叙述上钢五厂十二车间连续式加热炉通过大修改造,所采取的五项节能措施:减少炉底水管并绝热包扎;利用余热预热空气;炉墙和炉顶覆盖绝热材料;减少炉门并堵塞孔洞和健全计测装置,取得显著效果,热效率由原来30%左右提高到50%左右,重油平均单耗由原来70公斤/吨降低到45公斤/吨。并通过热工测定和热平衡计算对各项节能措施的效益进行分析。     

钢管光亮退火炉热过程的仿真与优化

首先建立了钢管退火炉热过程的数学模型,通过实验确定了辐射系数和对流传热系数,以某钢厂钢管光亮退火炉为对象进行仿真优化。结果表明:钢种、壁厚和炉速是影响退火炉内钢管温度的主要因素,不同钢种在冷却段温度差异比较明显,表面温度随钢管壁厚的增加而升高,壁厚对径向温差的影响主要体现在加热段和冷却段,随炉速的增加,加热段的温升越慢、径向温差越大,冷却段的温升越慢、径向温差越大,径向温差加热段存在多个拐点;正火工艺优化后,炉速降低,管排数增加,产量提高了16.3%;回火工艺优化后,管排数不变,炉速增加,产量提高了59.6%。     

铝箔退火炉的设计与应用

从改进炉子结构，延长使用寿命、提高炉子热效率、缩小炉子温差、降低能消耗、提高产品质量，保证安全生产的角度出发，进行铝箔退火炉的设计。设计中采用了高温轴流风机，卡口式加热元件，导热系数小、保温性能好的新型耐火材料及结构；气动压紧炉门和ＷＴ－１００高精度温度程控仪等先进技术，使铝箔退火炉结合合理，温度均匀，使用寿命长，热效率高。     

马钢CSP加热炉加热能力及使用寿命优化实践研究

针对马钢CSP加热炉的加热能力制约生产线品质提升的问题,分析了CSP加热炉生产中存在的耐材老化、燃烧、热损失、冷却系统、钢坯加热不均、氧化烧损、热工制度、炉压等问题,并对这些问题,在现场应用基础上提出了加强加热炉设备管理、空燃比及煤气压力控制、喷嘴堵塞及耐材烧损控制及炉墙保温,余热利用等改进措施,通过现场实绩表明,这些措施有效的提升CSP加热炉加热能力与使用寿命。     

带钢连续热镀锌退火炉预热区及无氧化加热区的热诊断

介绍了带钢连续热镀锌退火炉预热区及无氧化加热区热诊断的项目和方法,分析了实际空气过剩系数的数值及其受环境温度的影响,并介绍了实际诊断的案例和结果。本案例通过热诊断使热效率提高了2.5%,经维修和小范围改造又提高了1.5%,每年节约能源折合成标准煤约200t。     

侧喷加热退火炉内铝卷温度场的仿真研究

针对径向加热退火炉内传热效率低的问题,分析了炉内铝卷的传热过程,提出了侧喷加热的改进方法.利用ANSYS软件,对径向加热和侧喷加热退火炉内铝卷的温度场进行对比仿真.仿真结果表明,与传统的径向加热退火炉相比,在同样边界条件下,侧喷加热方式下铝卷的温度场分布更均匀,退火结束时,卷内温差只有0.6℃,有利于提高铝卷的退火质量;在同一时刻铝卷芯部的温度要比传统径向加热时高30℃左右,且整个铝卷的退火周期缩短了4h,从而提高了铝卷退火效率.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。