A review on the fundamentals of hydrogen-based reduction and recycling concepts for electric arc furnace dust extended by a novel conceptualization

The European Green Deal aims to make Europe climate neutral by 2050. This circumstance requires the metallurgical industry to move from carbon-based processes to hydrogen application. This work aims to summarize the current state of the research on thermodynamics and reaction kinetics in the scope of hydrogen-based reduction for Electric Arc Furnace Dust and present already existing and theoretically possible recycling processes using hydrogen. Thermodynamic calculations suggest three possible approaches to treat Electric Arc Furnace Dust using hydrogen as a reducing agent: Full reduction of iron and zinc oxide, selective reduction of iron oxide, and selective reduction of zinc oxide. In general, hydrogen can replace carbon seamlessly, leading to higher reaction kinetics but also to higher processing costs due to the high hydrogen price currently. However, zinc extraction from Electric Arc Furnace Dust allows for innovative concepts such as hydrogen recovery by reoxidation of gaseous zinc with water. In combination with selective zinc oxide reduction, this approach results in a recycling process with a low hydrogen consumption. However, additional high-quality research is necessary to provide a better data basis for a detailed economic view.     

现代炼铁工艺及低碳发展方向分析

分析了现代高炉炼铁和非高炉炼铁(直接还原、熔融还原)工艺特点和发展现状,从多个方面比较现有生产条件下各工艺的优缺点。从能源结构、生产规模及工艺成熟度阐述高炉炼铁在当前仍是国内主流工艺,并结合当前国内外低碳发展趋势和政策要求,提出高炉工艺降低碳耗的措施,明确了以“短流程”替代“长流程”和以新能源替代碳素冶金的发展方向,以最终实现“零碳炼铁”。结合现有的国际上的能源结构调整方向,指出了氢冶金的发展方向。     

The influence of Ohmic-vacuum heating on phenol,ascorbic acid and engineering factors of kiwifruit juice concentration process

The antioxidant, phenol, ascorbic acid, electrode corrosion and engineering factors of concentration process of kiwifruit juice by ohmic heating-vacuum conditions (OHVC) were evaluated and compared with ohmic heating under atmospheric conditions (OHAC). Results showed that the total phenol content was decreased with an increasing voltage gradient for both heating modes. The OHVC can better save the antioxidant capacity and ascorbic acid of concentrated samples than the OHAC. The processing time of OHVC was significantly higher than the OHAC at the same voltage gradient (P < 0.05). The electrode corrosion rate at the vacuum mode was 7- to 40-fold higher than the atmospheric mode. The energy efficiency at OHAC was lower than the OHVC. The energy consumption was found in the range of 3.37 to 3.75 MJ kg⁻¹ water for OHAC and 4.08 to 11.09 MJ kg⁻¹ water for OHVC. The electrical conductivity under the vacuum mode was lower than the atmospheric mode.     

Advances in radio frequency pasteurisation equipment for liquid foods: a review

Radiofrequency (RF) heating is an alternative emerging technology to conventional thermal methods; it has been employed for food pasteurisation, providing fast and volumetric heating. However, non-uniformity in the heating pattern has been reported. RF pasteurisation has been studied in different liquid foods. This review provides information about the RF heating mechanism and equipment used to pasteurise liquid food to control deteriorative or pathogen micro-organisms and the effect of the RF treatment on the quality of liquid foods. Developing an effective RF pasteurisation for liquid foods requires knowing the food dielectric properties, which determine the heating uniformity, temperature distribution and heating rate. The efficiency of continuous RF heating systems could depend on the fluid rate, resident time and absorbed power. RF heating can pasteurise liquid food, decrease microbial population and preserve the product's nutritional and physicochemical quality.     

Hydrogen generation characteristics of reduced DME steam reforming catalysts according to heating methods

The purpose of this study is to investigate the hydrogen generation characteristics of H₂-reduced dimethyl ether (DME) steam reforming (SR) catalysts using different heating processes. The effects of the H₂ reduction temperature and space velocity were investigated to identify an optimal reaction environment. Both the resistive and induction heating methods were used. The catalysts were prepared by impregnating copper over a γ-Al₂O₃ support. The Cu/Al₂O₃ catalysts with different loading amounts of 5–15 wt% Cu exhibited different characteristics when subjected to hydrogen reduction. The variation in acidity had a dominant effect on the DME-SR activity, and 15Cu/Al₂O₃ that underwent hydrogen reduction treatment at 500 °C attained improved performance at low temperatures and low formation of by-products, allowing for the achievement of its highest H₂ concentration of 74.08% at 375 °C. The induction heating reactor had an energy consumption that was about 25% lower than that of the resistive heating reactor.     

基于脉冲燃烧控制的退火炉热负荷分配模型

 脉冲燃烧控制技术以其良好的动态响应性、较高的炉温控制精度、较低的燃气消耗及污染物排放水平等优点,广泛应用于各类加热炉。对于立式退火炉而言,常见的加热模型有3种,即比例模型、窄带钢模型、正常模型。生产中操作人员可以根据带钢在加热段跑偏、瓢曲风险选择相应的模型,但上述这3种模型均无法避免因烧嘴频繁开启和关闭导致的辐射管骤冷骤热,进一步引起辐射管变形、开裂,点火电极、控制阀消耗异常以及煤气压力波动大等问题。为了降低烧嘴开启、关闭频次,达到降低烧嘴故障率、减缓辐射管开裂趋势等目的,提出了一种针对脉冲控制的退火炉专用“爬楼梯”式热负荷输出分配模型。通过拟合加热段板温控制器输出值与加热段各列热负荷输出值之间的关系,采用插值法得到加热段热负荷输出分配模型的修正函数,满足了模型计算值与板温控制器输出值相等的要求。通过调整加热段每一列热负荷输出上、下限,使加热段每列热负荷输出呈现“爬楼梯”式分布,实现了立式退火炉低功率加热段入口区域烧嘴不燃烧和出口区域烧嘴一直燃烧的功能。经过测试,在一个完整的燃烧周期内,爬楼梯式分配模型可大幅度降低烧嘴开启和关闭频次。当加热段板温控制器输出为89.6%时,传统模型控制下烧嘴开关频次达到324次,而“爬楼梯”式分配模型仅为32次。     

变频电源在铜冶炼除尘器中的应用分析

针对冶炼烟气的除尘效率的问题，在冶炼生产实际需求的基础上，通过对高压电源提效进行理论分析，对各种高压电源进行对比分析，结合试用的结果表明对于除尘器本体未进行改造的情况下，仅改造高压电源可以显著提升冶炼烟气的除尘效率^［1］。     

Finite difference analysis for entropy optimized flow of Casson fluid with thermo diffusion and diffusion-thermo effects

Heat transportation is a novel prospective in many thermal processes and presents dynamic applications in industrial and thermal polymer processing optimization. The importance of heat transportation is noted in heat exchangers, production of crude oils, combustion, petroleum reservoirs turbine systems, thermal systems, porous media, modeling of resin transfer nuclear reactions etc. In view of such thermal applications the main objective here is to examine entropy in unsteady magnetohydrodynamic of Casson fluid flow. Radiation in addition to dissipation and ohmic heating are analyzed. Entropy is scrutinized employing thermodynamic second law. Characteristics of Soret and Dufour are also examined. Main objective here is to examine irreversibility. Dimensionless version of differential system is obtained through suitable variables. The obtained partial differential system is solved through numerical scheme (Finite difference method). Physical features of fluid flow, temperature, entropy optimization and concentration have been explained. Variations of parameters on drag force, Nusselt number and solutal transfer rate are graphically discussed. Higher fluid parameter leads to improve in velocity and entropy rate. Larger values of radiation parameter boost up thermal field. Entropy rate and velocity have reverse trend for magnetic field. An intensification for concentration is found through Soret number. Higher approximation of Reynold number enhances skin friction and velocity. Thermal transfer rate is augmented versus radiation and magnetic variables.     

900 t/d浮法玻璃窑炉烤窑总结

详细介绍了国内900 t/d浮法玻璃窑炉烤窑的全过程,总结了一些经验.