电炉半钢转杯离心粒化制备铁粉工艺

摘要：为了实现钛精矿电炉冶炼副产品半钢的高附加值利用,提出了以半钢为原料,采用转杯与冷却水幕相结合的转杯离心粒化工艺制备铁粉,并作为硫酸法钛白还原剂的新工艺。实验研究了转杯直径和转速对铁粉粒度的影响规律,结果表明铁粉粒度随着转杯直径和转速的增大而减小;转杯直径为150mm、转速为1800r/min时,颗粒粒径小于0.45mm 的铁粉占比达到90.45%（质量分数）;建立了适用于转杯离心粒化颗粒粒度的预测模型,平均相对误差为 11.43%;利用扫描电镜观察了铁粉颗粒截面的显微结构,铁粉颗粒表面存在一层铁的氧化物;利用热重分析法研究了水幕对铁粉颗粒氧化程度的影响。论文最后提出了铁粉制备、余热回收与钛白制备相结合的新工艺。     

On the Evolution and Structure of a Radiation Fog Event in Nanjing

An extremely dense radiation fog event during 10-11 December 2007 was studied to understand its macro-/micro-physics in relation to dynamic and thermodynamic structures of the boundary layer, as well as its structural evolution in conjunction with the air-surface exchange of heat and water vapor. The findings are as follows. The extreme radiation fog process was divisible into formation, development, mature, and dissipation phases, depending on microstructure and visibility. This fog event was marked by rapid evolution that occurred after sunrise, when enhanced surface evaporation and cold air intrusion led to a three order of magnitude increase in liquid water content (LWC) in just 20 minutes. The maximum droplet diameter (MDD) increased four-fold during the same period. The fog structure was two-layered, with the top of both the surface-layer and upper-layer components characterized by strong temperature and humidity inversions,and low-level jets existed in the boundary layer above each fog layer. Turbulence intensity, turbulent kinetic energy, and friction velocity differed remarkably from phase to phase: these features increased gradually before the fog formation and decreased during the development phase; during the mature and dissipation phases these characteristics increased and then decreased again. In the development and mature stages, the mean kinetic energy of the lower-level winds decreased pronouncedly, both in the horizontal and vertical directions.     

面向船舶多种余热梯级利用的TEG-ORC联合循环性能

传统的温差发电（TEG）和有机朗肯循环（ORC）等技术难以兼顾船舶多种性质余热的不同特点,且利用率较低。本文提出了一种TEG-ORC联合循环船舶余热梯级利用系统,研究了ORC底循环蒸发压力变化对系统输出功率、热效率、多级余热利用量和成本等重要性能的影响。结果表明,TEG-ORC联合循环实现了发电成本和热效率的优化,在TEG/ORC底循环比为0.615的工况下,主机烟气余热利用率随ORC蒸发压力的增加在小区间波动,系统的余热利用功率、输出功率和热效率均随ORC蒸发压力的增加而增大,系统单位发电成本随ORC蒸发压力的增加而降低。在ORC蒸发压力达到0.9 MPa时,主机烟气余热利用率为62.15%,余热利用功率为1919.68 W,输出功率为139.22 W,热效率为7.25%,单位发电成本为3.09 ￥·(kW·h)–1。      

Olympics in Atlanta: a fight against physics

Environmental stress can become so severe that athletes, in spite of proper training, heat acclimation, and hydration level, are unable to maintain thermal balance. Such incompensable conditions occur when air temperature exceeds 35 degrees C and relative humidity becomes higher than 60%. At these high environmental temperatures, the heat liberated during exercise can only be lost by evaporation of sweat, and therefore water vapor pressure sets limits on the possible rate of evaporation. Calculations are presented for the required and the maximal possible sweat evaporation rate for high-intensity, long-duration events, using marathon racing as an example. The consequence of the environmental heat stress is that the athlete must reduce the speed of running considerably to prevent potential heat injury. In certain extreme environmental conditions, sporting events should be canceled or postponed.     

钢铁企业余热余能回收利用措施研究

文章以某钢铁企业为例,分析了钢铁企业余热余能利用现状及存在问题、影响余热余能回收利用的主要因素,提出余热余能回收利用措施,通过回收低品质余热替代采暖蒸汽、增加发电用户消化富余蒸汽、关停及优化洗浴分散用户、新建燃气-蒸汽高效发电系统等,实施后可以做到区域供热平衡,减少蒸汽消耗,提高余热利用效率。     

Structure formation in a KhN65VMBYu alloy upon changes in its chemical composition

The plastic properties and structure of the KhN65VMBYu alloy of two heats are studied; one heat is performed using pure charge materials, and the other heat is performed using a charge with 79% recycled material. The difference in the plasticities of the samples is found to be caused by a change in the chemical composition of the alloy and, hence, its structure. An increase in the content of iron and refractory metals in the alloy produced with an addition of a recycled material results in the formation of a significant quantity of close-packed phases, which are retained upon heat treatment, even during solidification. These phases bring about a sharp decrease in the plasticity of the alloy.     

以提升自发电为突破口加快推进钢铁绿色低碳发展

提升余热余能发电水平是提高钢铁系统能效和竞争力的有效途径,也是实现钢铁绿色低碳发展的重要举措。余热余能自发电率是钢铁能源转换功能的关键表征指标,通过制定行业标准科学评判余热余能自发电率具有重要意义。研究认为,按目前成熟技术和管理能力,钢铁行业有提升二十个百分点自发电率的潜力,将带来显著的经济效益和节能降碳效益。以提升自发电为突破口,能够加快推进钢铁绿色低碳发展。     

Influence of silicon on smelting-dust formation

The formation of smelting dust is analyzed. On the basis of a distillation mechanism, it is shown that the main factor affecting the quantity of dust formed is the surface temperature of the melt, which depends both on the initial temperature of the melt and on the reactions in the melt. The exothermal oxidation of impurities heats the melt surface and so increases the evaporation of iron and hence dust formation. Silicon dissolved in the hot metal is oxidized very rapidly and with considerable heat generation; as a result, there is a considerable increase in dust formation.     

2 kg试验焦炉炼焦过程传输行为的数值模拟

为了研究炼焦过程中煤传热传质现象的规律,建立2 kg试验炼焦过程流动、传热及传质过程的数学模型。模型中将装炉煤/焦饼假设为多孔介质,结合水分蒸发冷凝与挥发分析出子模型,模拟了配合煤焦化过程中的传热、水分传递、挥发分析出及荒煤气流动等现象,并分析水分含量对煤层中心温度的影响。结果表明,数学模型可反映试验焦炉炼焦过程中的传输现象。炼焦过程中,焦饼温度会受到烟道回流空气的影响,顶部装炉煤成焦所需时间较长。在水蒸气冷凝的作用下,装炉煤中心水分含量会在焦化过程中逐渐升高,并使装炉煤中心温度达到100 ℃时形成恒温平台。     

500万t/a带式焙烧机球团精矿干燥系统设计

介绍了某500万t/a大型带式焙烧机球团生产线的干燥系统的工艺设计过程。根据干燥物料特性和生产需求的研究，确定了载热体形式为热烟气，干燥设备选用干燥筒，干燥方式采用顺流干燥。通过物料平衡和热平衡计算，得出了干燥筒的铁精矿处理能力、水分蒸发量及所需热量，进而确定了干燥筒的规格为5 m×24 m，干燥筒驱动功率为859 kW，选用液压马达作为驱动设备。选用热风炉的供热能力为1.32×108 kJ/h。选用布袋除尘器＋引风机作为烟气排放和除尘设备，引风机和除尘器处理风量为20万m3/h，引风机全压为3 000 Pa。     

2 kg试验焦炉炼焦过程传输行为的数值模拟

为了研究炼焦过程中煤传热传质现象的规律,建立2 kg试验炼焦过程流动、传热及传质过程的数学模型。模型中将装炉煤/焦饼假设为多孔介质,结合水分蒸发冷凝与挥发分析出子模型,模拟了配合煤焦化过程中的传热、水分传递、挥发分析出及荒煤气流动等现象,并分析水分含量对煤层中心温度的影响。结果表明,数学模型可反映试验焦炉炼焦过程中的传输现象。炼焦过程中,焦饼温度会受到烟道回流空气的影响,顶部装炉煤成焦所需时间较长。在水蒸气冷凝的作用下,装炉煤中心水分含量会在焦化过程中逐渐升高,并使装炉煤中心温度达到100 ℃时形成恒温平台。     

210t铁水包静置温降过程的数值模拟

通过数值模拟方法,研究了210 t铁水包静置温降过程中铁水包包盖和铁水液位对铁水温降速率的影响.模型中使用S2 S辐射传热模型来考虑渣层与包盖间的辐射传热,并分析了不考虑铁水自然对流对计算结果的影响.结果表明:铁水静置过程计算中,考虑铁水自然对流现象能够明显提高铁水温度的均匀性,并提升计算结果的准确性.使用包盖能够有效...     

Controlling Radiative Heat Transfer Across the Mold Flux Layer by the Scattering Effect of the Borosilicate Mold Flux System with Metallic Iron

The present study proposes a countermeasure for regulating total heat flux through the mold flux layer by designed mold flux with additive metallic iron particles. The heat flux through the B₂O₃-CaO-SiO₂-Na₂O-CaF₂-Fe system was investigated using the infrared emitter technique to evaluate total flux density across the mold flux film. Both scanning electron microscope (SEM) and X-ray diffraction analysis were employed in order to identify the morphological and compositional changes of the crystalline phase, according to increasing iron contents in the mold flux. It was confirmed that the crystalline layer of studied mold fluxes does not have a meaningful effect on the total heat flux density due to the similar structure and fraction of the crystalline phase. The extinction coefficient was measured for glassy mold fluxes using an ultraviolet/visible and a Fourier transformation-infrared ray spectrometer in the range of 0.5 to 5 μm. For analyzing the scattering behavior of iron particles on the extinction coefficient, the number density and diameter of particles were observed by an automated SEM (auto-SEM). With these data, Mie scattering theory is adopted to define the scattering behavior of dispersed iron droplets in glassy matrix. It was found that the theoretical scattering coefficient demonstrated about 1623 to 3295 m^?1, which is in accordance with the experimental results. In doing so, this study successfully achieves the strong scattering behavior that would contribute greatly to the optimization of overall heat flux through the mold flux film during the casting process.     

Evaporation Theory for Deformable Soils

Desiccation of a deformable soil is basically the removal of water by evaporation, which is controlled by evaporativity and evaporability. Surface evaporation improves the trafficability, which is essential for the access of construction equipment in areas reclaimed with soft clay. The existing traditional methods for evaluating evaporation cannot account for the deformation of soils during evaporation. Therefore, a theoretical model for predicting the rate of evaporation from the surface of a deformable material is proposed. The model is based on a system of equations for coupled heat and mass transfer in unsaturated soils. The modified pressure plate extractor test and glass desiccator test were carried out to obtain the soil-water characteristic curve for a deformable soil. A column-drying test was conducted to investigate one-dimensional water flow, heat flow, and evaporation in the surface. A finite difference program was developed to solve the coupled nonlinear partial differential equations, which permits the study of liquid, diffusive vapor, and heat flows in the deformable soil. Comparison between measured and simulated values shows good agreement.     

Hydrogen absorption of incoherent TiC particles in iron from environment at high temperatures

The effect of atmosphere in heat treatment on the hydrogen trapping of incoherent TiC particles in iron has been studied in order to clarify the origin of hydrogen trapped by incoherent TiC particles. The hydrogen trapped by incoherent TiC particles in iron after austenitizing and tempering treatments in air, in a nonprotective argon atmosphere, and in an ultrahigh vacuum (UHV) was identified and quantitatively measured by thermal-desorption spectrometry (TDS). Results showed that incoherent TiC particles in iron do not trap hydrogen at ambient temperature by a cathodic-charging method. It was justified that incoherent TiC particles trap hydrogen during high-temperature heat treatment in nonprotective atmospheres. The amount of hydrogen trapped by incoherent TiC particles decreases with increasing heat-treatment temperature, which is well explained by the equilibrium concentration of hydrogen trapped by incoherent TiC particles in iron under an atmosphere containing water vapor. The hydrogen is supplied through water-vapor oxidation of iron at high temperatures. According to this model, a binding energy between hydrogen and incoherent TiC of 53 kJ/mol was obtained. The energy barrier for hydrogen to jump into incoherent TiC was determined to range from 21 to 35 kJ/mol, which is too high for hydrogen to be trapped by incoherent TiC at low temperatures.     

降雨和蒸发对粉质黏土边坡稳定性影响分析

以山西某露天矿粉质黏土边坡为工程背景,基于饱和-非饱和渗流理论及流固耦合原理,采用有限单元法研究了降雨和蒸发作用下边坡孔隙水压力、体积含水量、位移及应变变化特点,并对不同降雨强度和蒸发强度下的边坡孔隙水压力和安全系数进行了对比分析。研究结果表明:降雨入渗导致浅层土体含水量增大,基质吸力降低,降低边坡稳定性,降雨强度越大,边坡稳定性下降越快;蒸发会降低浅层土体的含水量,增加吸力,提高边坡稳定性,且蒸发强度越大,安全系数提高越快;边坡孔隙水压力和安全系数与天气条件之间存在滞后关系,滞后时间随土体深度增加而增加。     

Effects of local restriction of evaporation and moderate local ventilation on thermoregulatory responses in exercising humans

Ten healthy young men participated in two series of three trials: series 1 (C1) with, or without, local restriction of evaporation (either on the trunk or on the legs) and series 2 (C2) with, or without, local moderate nitrogen ventilation (40 l.min-1) under an impermeable garment (trunk or leg ventilation). After 60-min rest in a thermoneutral environment, the subjects exercised in a warm environment [30 degrees C, 47% relative humidity (rh) during C1 and 29% rh during C2] on a cycle ergometer for 60 min at 70 W during C1 or at 60 W during C2. During C1, local covering with plastic foil did not increase internal temperature, but increased the mean skin temperature with a higher effect in the case of leg restriction. The trunk skin temperature was affected by the leg covering while the leg skin temperature was not changed by the trunk covering. Only the local sweat rate of the trunk was increased by the two restriction conditions. During C2, internal temperature was decreased by local ventilation while mean skin temperature was reduced only by trunk ventilation. The local ventilation affected only trunk skin temperature with a greater decrease during trunk ventilation. Trunk ventilation did not influence the skin temperature of the legs while ventilation of the legs decreased trunk skin temperature. In addition, leg ventilation decreased the sweat rate of the legs. The impermeable suit worn during C2 led to a greater physiological strain compared to the plastic film worn during C1 even with local ventilation under the impermeable garment. As expected, limiting sweat evaporation led to an increase in physiological strain. Microclimate ventilation at a rate of 40 l.min-1 was not sufficient to allow total heat dissipation but allowed 60-min exercise in a warm environment to be completed without excessive heat accumulation. It would appear that ventilation of the trunk locally was the best solution because of the smaller increase in skin temperature and higher sweating capacity of the trunk.     

Numerical and Experimental Investigation on Heat Propagation Through Composite Sinter Bed With Non-Uniform Voidage:Part Ⅰ Mathematical Model and Its Experimental Verification

The mechanisms of heat transfer through the sinter beds of the MEBIOS process are discussed and their comprehensive mathematical model is proposed.The MEBIOS process,the concept of which has been proposed earlier by the authors,allows using both coarse and fine particles of iron ores in the same sinter bed.The study includes two parts.The first part describes the model content and the results of its experimental verification.The model accounts for coal combustion,limestone decomposition,moisture evaporation...