Influences of Binders on Properties of Highalumina Repairing Mix for Medium-frequency Induction Furnace

Three kinds of high-alumina repairing mixes for medium-frequency induction furnace were prepared by ramming method with sodium silicate, phosphoric acid and aluminium dihydrogen phosphate as binder, respectively. Physical properties of the specimens heat treated at different temperatures were tested and compared. The results show that the specimen bonded by sodium silicate behaves much higher strength after fired at 1 600 ℃ compared with the specimen, bonded by phosphoric acid or aluminium dihydrogen phosphate. Due to more liquid phase formation the properties of specimen bonded by sodium silicate are poor with a low strength and a large volume shrinkage at high temperatures. Meanwhile. the speeimen bonded by phosphoric acid and aluminium dihydrogen phosphate, respectively, show relatively high strengths and slight volume expansions at high temperatures because of in-situ mullite formation.

Numerical Simulation of Electromagnetic Field and Temperature Field in Medium-Frequency Induction Furnace Melting Process

A mathematical model for describing the melting process in the medium-frequency induction furnace was developed.Finite difference method was applied to deal with coupling electromagnetic field and temperature field in the melting process.The magnetic induction,temperature distribution and the phase interface moving characteristic during melting of the furnace burden were calculated.The effects of the direct current and inductive heating frequency on the process were analyzed.The simulation results show that:In the direction of burden radius,magnetic induction decreases from the outside of the burden to the center.Solid/liquid interface moves gradually from the outside of the burden to the center.The movement speed increases when the burden begins to melt.In the direction of the burden height,the distribution of eddy current in the surface is accord with the edge effect of the coil.Solid/liquid interface moves gradually from the center to the two sides.The direct current has a greater effect on the electromagnetic field and temperature field than frequency.

Corrosion Mechanism of Alumina-magnesia Dry Materials for Smelting Manganese/chromium Steel in Coreless Medium Frequency Induction Furnaces

Alumina-magnesia dry materials are widely used in induction furnace linings, but they show different kinds of damage when melting different kinds of alloy steel. In this paper, the chemical composition, phase composition, and microstructure of the post-use dry materials for the working liners melting different kinds of steel were evaluated. Furthermore, the corrosion mechanism of the steel on the furnace lining materials was comprehensively analyzed. The findings reveal a significant ability of the Mn element in the molten steel to diffuse and penetrate into the refractories. Mn oxidizes to form MnO at the steel-refractory interface, and then forms a liquid phase with Al_(2)O_(3). The Cr element is dissolved into corundum and spinel of the refractories, resulting in lattice defects and structural damage of the materials. TiO2reacts with Al_(2)O_(3) to form Al_(2)TiO_(5), which plays a crucial role in preventing crack formation and propagation. Part of Ti4+dissolves into magnesia-alumina(MA), densifying the materials. TiO2also slows down the reaction between the Cr element and refractory components, further improving the corrosion resistance of the materials.

Numerical analysis on Joule heating of double-loop channel induction furnaces

In order to investigate Joule heating power,a three-dimensional finite element model(FEM) was developed to predict Joule heating power in the channels of double-loop inductor. The simulated results were compared with experimental data from low load trials for a 400 kW inductor. The results,such as power factor and Joule heating power,show reasonable correlation with experimental data,and Joule heating rate reaches the maximum at the corners and the minimum at the centre of the cross-section area. With increasing relative permeability of iron core,length of coils,current frequency and resistivity of metal melt,the power factor and Joule heating power change. It is concluded that current frequency,the resistivity and length of the coil play a critical role in determining the power factor and Joule heating power,whereas relative permeability of the magnetic core shows no significant influence on them.

Improvement of the Structure and the Electromagnetic Characteristics of an Induction Ladle Furnace

Based on a numerical analysis of the alternating electromagnetic field in the process of Steel refining with an induction ladle furnace (ILF), the optimization of the structure of ILF and the electromagnetic field for melting is realized in the present work. The optimization of the ILF by outward extension of inner yokes can decrease the magnitic flux leakage obviously, reduce the eddy current energy loss dramatically and then, decrease the total power consumption.

Melting Time Prediction Model for Induction Furnace Melting Using Specific Thermal Consumption from Material Charge Approach

A system-level evaluation was used to analyze the induction furnace operation and process system in this study. This paper presents an investigation into the relationship between the instantaneous chemical composition of a molten bath and its energy consumption in steelmaking. This was evaluated using numerical modelling to solve for the estimated melting time prediction for the induction furnace operation. This work provides an insight into the lowering of energy consumption and estimated production time in steelmaking using material charge balancing approach. Enthalpy computation was implemented to develop an energy consumption model for the molten metal using a specific charge composition approach. Computational simulation program engine (CastMELT) was also developed in Java programming language with a MySQL database server for seamless specific charge composition analysis and testing. The model performance was established using real-time production data from a cast iron-based foundry with a 1 and 2-ton induction furnace capacity and a medium carbon-based foundry with a 10- and 15-ton induction furnace capacity. Using parameter fitting techniques on the measured operational data of the induction furnaces at different periods of melting, the results from the model predictions and real-time melting showed good correlation between 81% - 95%. A further analysis that compared the relationship between the mass composition of a current molten bath and melting, time showed that energy consumption can be reduced with effective material balancing and controlled charge. Melting time was obtained as a function of the elemental charge composition of the molten bath in relation to the overall scrap material charge. This validates the approach taken by this research using material charge and thermodynamic of melting to optimize and better control melting operation in foundry and reduce traditional waste during iron and steel making.

Features and control methods of the galvanneal furnace

The recent rapid developments in the automobile industry have demanded the extensive use of gaivannealed （GA） steel sheets.In particular,the development of lightweight automobiles is putting increasingly higher requirements on the strength of GA steel sheets.The galvanneal furnace,which is used for processing galvannealed steel sheets,is typically composed of the induction heating section,holding section and fog cooling section.This paper described the structural characteristics of each component of the galvanneal furnace,and analyzed temperature control methods of the galvanneal furnace that are important for the successful production of high-strength GA steel sheets for automotive applications.

基于TRNSYS的太阳能-电能互补采暖系统研究

针对我国北方农村地区冬季采暖污染严重、碳排放量大等问题,文章以沈阳市某地区典型农村单体式住宅为研究对象,综合考虑太阳能、电能,提出2套清洁供暖方案。首先对太阳能集热器的集热倾角和面积的选择进行优化,然后选取沈阳市供暖季温度较低的2天,根据天气情况分别作为晴天与阴天典型日,最后利用TRNSYS软件对供暖方案在典型日天气条件下模拟运行。结果表明在典型日天气条件下本研究提出的2种供暖方案均满足环保、室内温度适宜等采暖需求,且太阳能集热器+变频电磁采暖炉供暖方案更为节能。

感应熔炼炉炉衬损耗监测系统设计

为进一步消除炼钢和铸造行业中机械生产和加工设备的安全隐患,基于感应接触式炉衬损耗监测技术,设计一种炉衬损耗监测系统。该系统在感应熔炼炉运行过程中实时采集感应圈回路与中间金属层回路的电流值,根据两回路电流值判断感应熔炼炉是否出现炉衬损耗,评估损耗状况,并在回路电流值达到设定阈值后及时发出对应的信号提醒工作人员。经实验验证表明,系统能够提升炉衬损耗监测的可靠性,同时提高了熔炼炉生产的安全性以及工作人员对炉衬损耗状况判断的便利性。

立式退火炉纠偏系统应用技术分析

介绍了冷轧后处理连续生产线炉内纠偏系统的种类、工作原理,并从抗干扰能力、工作环境和故障维修等方面分析了电感式纠偏系统与雷达式纠偏系统在退火炉中使用时的优缺点和技术差异。

真空感应悬浮熔炼技术在高纯材料制备中的应用

叙述了真空感应悬浮熔炼技术在制备高温、高纯等合金材料方面的优点,介绍了真空感应悬浮炉的关键技术以及装备的最新发展与应用,讨论了该技术在熔炼高质量特种钢等新材料方面的应用,并分析了该技术在熔炼其他材料等领域的应用及可行性。

多重化逆变电源在有心感应电炉的应用

传统有心感应电炉的供电由感应器、平衡电抗、电容平衡电路组成,一般采用调压器分档接触器控制感应器电压,调节感应器的功率。接触器切换电压挡位,造成感应器熔沟巨大的电流冲击,是影响感应器的稳定运行及寿命主要因素。本电源装置是基于双DSP+双FPGA+CPLD核心控制器的控制装置,主要由主电路部分、控制部分组成。主电路部分主要包括:空开、主接触器、软启动限流电阻和辅助接触器、滤波器和功率单元体构成的换流链。控制部分通过对电网电压电流、负载电流、补偿电流进行控制,最终实现功率控制的目的:直流侧电压动态均压策略;较高开关频率下的功率器件驱动和散热设计;滤波器的设计和应用。基于低压器件H桥级联实现高压功能的硬件设计应用。探索一种新的供电方案,保障供电安全,降低能耗,营造“绿色电网”具有十分重要的现实意义。

VIM真空感应炉真空度修复分析

以太钢技术中心基础研究所的德国ALD真空感应炉作为研究对象,其连续服役十余年,大量的冶炼试验对真空炉的抽真空系统造成了严重的影响,工作真空度不断降低,导致钢锭质量下降。通过分析真空炉抽真空泵级系统原理,提出将真空泵级系统进行拆解维护修复方案。经过实践证明,该修复方案切实可行,能够大幅度提高真空感应炉的工作真空度。

变频感应加热炉电网频率波动下低压智能断路器过流保护控制

电网频率波动会导致电流波形在短时间内发生变化,从而影响过流保护控制的响应速度。为了保障电网频率波动下低压智能断路器过流保护控制的稳定可靠性,提高变频感应加热炉电力系统的保护性能,提出变频感应加热炉电网频率波动下低压智能断路器过流保护控制方法。利用PCL-818L数据采集卡,采集变频感应加热炉供电系统中的电压电流信号;通过强化学习Q-Learning算法,消除信号中的电网频率波动,提高断路器的稳定性;采用引入滑动时间窗口的三段电流保护方法,实现低压智能断路器的过流保护控制。实验结果表明,所提方法能够在有效消除电网频率波动干扰的情况下,提高断路器过流保护控制精度、效率以及稳定性。

ICP-MS法和GF-AAS法检测乳粉中铬元素的测量系统评价

铬元素是食品质量安全重点监测项目,GB 5009.123—2023《食品安全国家标准食品中铬的测定》中规定了食品中铬的2种常用检验方法:石墨炉原子吸收光谱(graphite furnace atomic absorption spectrometry,GF-AAS)法和电感耦合等离子体质谱(inductively coupled plasma mass spectrometry,ICP-MS)法。使用Minitab统计分析工具,运用控制图法、独立样件法、t检验法及方差分析法对上述2种常用检验方法测量系统的稳定性、偏倚、线性、重复性与再现性进行分析。结果表明:2种检测方法测量系统极差图和均值图均无异常点,组内误差处于统计受控状态,稳定性良好;量具线性和偏倚分析结果均不存在显著偏倚和显著线性误差;量具R&R报告分析结果表明,ICP-MS法和GF-AAS法测量系统重复性和再现性良好;双因子方差分析表明,样品是唯一显著影响测量误差的因子;研究变异分析表明,测量系统误差可以接受。ICP-MS法和GF-AAS法不仅能有效保障乳粉中铬元素含量检测数据的可靠性和可重复性,为实验室进行测量系统的误差分析与控制提供科学依据,同时也为乳制品中其他重金属检测及其他食品中重金属检测的测量系统评价提供一定参考。

钛含量对443超纯铁素体不锈钢凝固组织的影响

通过真空感应炉浇注不同钛含量的443超纯铁素体不锈钢铸锭,并分析研究不同钛含量对443超纯铁素体不锈钢铸锭凝固组织的影响。试验结果表明:443超纯铁素体不锈钢凝固过程中先从液相中析出高温铁素体,随着温度降低析出TiN和NbC。钛含量越高凝固组织的等轴晶率越高、晶粒尺寸越小,在[Ti]为0.3%时,铸锭组织全部为等轴晶,等轴晶率为100%,平均尺寸达到0.56 mm,晶粒球化率为0.85。

火焰原子吸收光谱法、石墨炉原子吸收光谱法和电感耦合等离子体发射光谱法测定地表水样中铜的研究方法对比

采用火焰原子吸收光谱法(FAAS)、石墨炉原子吸收光谱法(GF-AAS)和电感耦合等离子体发射光谱法(ICP-OES)分别测定地表水中的铜,对检出限、精密度、正确度、低浓度环境样品测试等指标进行对比。实验结果表明,三种方法对于测定地表水中铜,测试结果无显著差异;与FAAS和ICP-OES法相比,GF-AAS法具有较低的检出限、较高灵敏度,对于测定低浓度环境样品具有较高的准确性。

Numerical Analysis and Experimental Verification of the Behaviour of Solid Inclusions in Induction Crucible Furnaces

The paper refers to the dynamics of solid inclusion in the turbulent flow of liquid metal in induction furnaces. The numerical analysis is carried out adopting LES-based Euler-Lagrange approach in the limit of dilute conditions.The admixing of carbon particles in induction crucible furnace from the open surface of a melt is simulated.The behaviour of the particles in the bulk of the flow is illustrated as well as compared with the industrial observation of the open surface of the alloy.The paper also contains the description of the novel experimental technique,which is proposed for the verification of the numerical model.The experiment deals with ferromagnetic particles in the flow of Wood's metal in the small induction crucible furnace.This experiment confirms the satisfactory agreement with the numerical results.

Boron Removal From Metallurgical Grade Silicon by Molten Slag Refining in Induction Furnace

The impurities Al,Ca,Ti,B,P etc in metallurgical grade silicon(MG-Si)can be effectively removed by refining using molten slag based CaO-SiO_2,and it is especially effective for boron removal.The experiments of boron removal were studied using CaO-SiO_2 binary slag in induction furnace.The results showed that the distribution coefficient of boron(L_B)between slag and silicon increased with more proportion of CaO/SiO_2(mass%).It was advantaged to boron removal for higher basicity of slag,so the boron in MG-Si was reduced from 18ppmw to 1.4ppmw with the addition of Li_2O and K_2O to CaO-SiO_2 slag.The proportion of SiO_2 in slag affected the oxidizing capacity of slag,which reduced the efficiency of boron removal.

GF-AAS与ICP-MS测定水中总铬含量的方法比对及其不确定度评定

石墨炉原子吸收光谱(GF-AAS)法和电感耦合等离子体质谱(ICP-MS)法是灵敏度较高的2种测定水中铬含量的方法。文中采用357.9 nm与429.0 nm波长条件下GF-AAS法、52与53质核比条件下ICP-MS法测定水质铬标准物质中总铬元素含量,从标准曲线、准确性、重复性、加标回收率、检出限、定量限、测量不确定度评定多个方面进行对比分析。结果表明,4组测定条件下,标准物质测定结果均在标准值不确定度范围内。其中,429.0 nm波长GF-AAS法测定结果相对其他3组显著偏低(P<0.05);ICP-MS法在检出限、定量限方面优于GF-AAS法;GF-AAS法测定结果357.9 nm波长优于429.0 nm波长。