Modeling and optimization method featuring multiple operating modes for improving carbon efficiency of iron ore sintering process

Iron ore sintering is one of the most energy-consuming processes in steelmaking. Since its main source of energy is the combustion of carbon, it is important to improve the carbon efficiency to save energy and to reduce undesired emissions. A modeling and optimization method based on the characteristics of the sintering process has been developed to do that. It features multiple operating modes and employs the comprehensive carbon ratio (CCR) as a measure of carbon efficiency. The method has two parts. The first part is the modeling of multiple operating modes of the sintering process. K-means clustering is used to identify the operating modes; and for each mode, a predictive model is built that contains two submodels, one for predicting the state parameters and one for predicting the CCR. The submodels are built using back-propagation neural networks (BPNNs). An analysis of material and energy flow, and correlation analyses of process data and the CCR, are used to determine the most appropriate inputs for the submodels. The second part of the method is optimization based on a determination of the optimal operating mode. The problem of how to reduce the CCR is formulated as a two-step optimization problem, and particle swarm optimization is used to solve it. Finally, verification of the modeling and optimization method based on actual process data shows that it improves the carbon efficiency of iron ore sintering.     

基于正交信号校正的连续退火机组带钢质量预测方法

连续退火是改善带钢的力学性能的关键过程。但在实际生产过程中,连续退火过程机理复杂,并且对带钢质量的检测有很大的时间滞后,这给提高带钢质量带来了很大的障碍。文章利用正交信号校正提取与带钢质量密切相关的过程信息,选用偏最小二乘方法构建更为精准的带钢质量预测模型,具有良好的预测性能,可以及时准确地在线估计带钢质量。通过对现场实际数据的仿真分析证明了所提出方法的可行性和有效性。     

Mechanism of heterogeneous distribution of Cr-containing dispersoids in DC casting 7475 aluminum alloy

The actual effective partition coefficients of Mg and Cr in a cross-section of a dendrite arm in a direct-chill (DC)-casting ingot of 7475 aluminum alloy are obtained. Meanwhile, by analyzing the microstructure, the mechanism of the heterogeneous distribution of E (Al₁₈Mg₃Cr₂) dispersoids in this DC ingot is revealed. The results show that the actual effective partition coefficients of Mg and Cr are 0.650 and 1.392, respectively, and they describe the heterogeneous distributions of Mg and Cr along the direction of radius of the cross-section of the dendrite arm of the alloy. After homogenization treatment at 470 °C for 24 h, Mg diffuses uniformly, but Cr hardly diffuses. Both the concentrations of Mg and Cr and the sites of heterogeneous nucleation in the alloy are the determinants of the formation of E dispersoids simultaneously. The heat treatment at 250 °C for 72 h provides a large number of the sites of heterogeneous nucleation of the formation of fine E dispersoids that will be formed in the center of the cross-section during the subsequent heat treatment at higher temperature.     

Physical modeling and numerical simulation of electromagnetic stirring in a slab continuous casting mold

Through physical modeling and numerical simulation,the flow field in a slab continuous casting mold with electromagnetic stirring is measured under different casting parameters and stirring currents. To qualitatively evaluate the flow field in the mold,two indexes,i. e.,mold flux entrapment and velocity uniformity,are proposed.Based on these two indexes,some optimized stirring parameters under different casting conditions can be determined.     

Modelling and optimisation of biomass injection in ironmaking blast furnaces

Biomass is a renewable and potentially carbon-neutral energy source and can be a promising alternative to fossil fuels in the ironmaking industry. Pulverised biomass injection (PBI) is the most promising technology to use biomass-based materials in ironmaking blast furnaces (BFs). This paper reviews key aspects of recent research relating to biomass combustion in the raceway region: experimental studies, numerical studies, and the application of the research findings to optimise BF practice. In the experimental part, the pretreatment of raw biomass to produce pyrolysed biochar products for improving applicability in BFs is reviewed. The properties of raw biomass and biochar are compared with the main requirements for injection into BFs, and the process tests that have been employed at lab- and pilot-scales are reviewed. In the modelling part, a comprehensive overview of mathematical modelling of biomass combustion in BFs is presented, ranging from turbulent flow to heat transfer and mass transfer, as well as key reaction models for simulating the lower part of the BF. With respect to the application of the research, in-furnace phenomena understanding, operation optimisation, and facility design are reviewed, including the co-firing of biomass and coal. In addition, heat and mass balance modelling has been used to demonstrate the operating window of feasible operations using PBI. Life cycle assessment has been reviewed to demonstrate PBI's environmental credentials. Based on the aspects reviewed, conclusions have been drawn on the strengths, limitations, and outlook of PBI studies. This paper offers a comprehensive review of the combustion of biomass in BFs and should prove useful for process understanding, design and optimisation towards green ironmaking technology.     

New training strategies for neural networks with application to quaternary Al–Mg–Sc–Cr alloy design problems

This study concerns the training of a neural network in multiple stages considering minimization of errors from multiple data/pattern resources. The paper proposed a dual stage multi-resource data training scheme using multi-objective genetic algorithm. The training scheme has been used for the design and development of efficient neural network model focusing on missing, but most informative domains of the data set by means of introducing only a few patterns from missing domain treated separately during the later stage of training. The trained model has been used to design a quaternary Al–Mg–Cr–Sc alloy system, from the information subsets of binary Al–Cr and the ternary Al–Mg–Sc alloys. The validity of the proposed algorithm has been discussed in light of the evolution of the ageing characteristics of the new aluminium alloy system.     

Low-loss B18R065 and B20R070 grain oriented electrical steels for grade 1 energy efficiency distribution transformers

To reduce distribution transformer losses and carbon dioxide emissions,in recent years,the major countries in the world have issued mandatory standards for high-energy efficiency in distribution transformers.In 2013,China has carried out a new standard GB 20052-2013.To meet the update of the standard and energy efficiency,it is important to enhance the magnetic properties of core materials.The new products B18R065 and B20R070 which are developed by Baosteel,are successfully used for grade 1 energy efficiency distribution transformers.And Baosteel becomes one of the companies which can supply both the 0.20 mm and the 0.18 mm gauge grain oriented electrical steels (GOES) in the world.The development principle,material properties,and transformer performance of B18R065 and B20R070 were introduced,which were expected to be a useful reference for materials selection by transformer manufacturers.     

Continuous reduction of the oxide scale of hot-rolled steel strip in hydrogen

The continuous reduction in the oxide scale of hot-rolled steel strip in H₂–N₂ atmosphere was simulated in laboratory. Scale specimens were reduced in 20% H₂–N₂ or 50% H₂–N₂ atmosphere. The sample weight losses were measured after soaking at 550, 700 and 800°C. In both atmospheres, specimen reduced at 700°C showed the minimum weight loss after soaking for 240?s. At 700 and 800°C, higher hydrogen concentration accelerated the reaction in the beginning of soaking, but had little effect once the dense-reduced iron layer formed. While at 550°C, the reduced iron kept growing in porous structure and the weight loss rate increased significantly in higher H₂ concentration.     

Cost reduction of alloying element in high strength steel plate by optimization of controlled cooling technology

Controlled cooling technology is getting more and more attention with the development of thermal-mechanical control process.In the past decade,achieving the given finish cooling temperature was the sole goal for the technology.However,with the research and development of new steels such as super high strength steel,researchers have in recent years realized the determinate effects that different cooling paths have on the finish cooling temperature and paid more attention to the control of the cooling rate.This paper focuses on not only the optimization of the controlled cooling system with high precision and fast cooling rate,but also the research and development of the high strength steel plate with reduced alloying component.